Effect of added mass on treadmill performance and pulmonary function.

PubMed

Walker, Rachel E; Swain, David P; Ringleb, Stacie I; Colberg, Sheri R

2015-04-01

Military personnel engage in strenuous physical activity and load carriage. This study evaluated the role of body mass and of added mass on aerobic performance (uphill treadmill exercise) and pulmonary function. Performance on a traditional unloaded run test (4.8 km) was compared with performance on loaded tasks. Subjects performed an outdoor 4.8-km run and 4 maximal treadmill tests wearing loads of 0, 10, 20, and 30 kg. Subjects' pulmonary function (forced expired volume in 1 second [FEV1], forced vital capacity [FVC], and maximal voluntary ventilation [MVV]) was tested with each load, and peak values of heart rate, oxygen consumption ((Equation is included in full-text article.)), ventilation (VE), and respiratory exchange ratio (RER) were measured during each treadmill test. Performance on the 4.8-km run was correlated with treadmill performance, measured as time to exhaustion (TTE), with the strength of the correlation decreasing with load (r = 0.87 for 0 kg to 0.76 for 30 kg). Body mass was not correlated with TTE, other than among men with the 30-kg load (r = 0.48). During treadmill exercise, all peak responses other than RER decreased with load. Pulmonary function measures (FEV1, FVC, and MVV) decreased with load. Body mass was poorly correlated with treadmill performance, but added mass decreased performance. The decreased performance may be in part because of decreased pulmonary function. Unloaded 4.8-km run performance was correlated to unloaded uphill treadmill performance, but less so as load increased. Therefore, traditional run tests may not be an effective means of evaluating aerobic performance for military field operations.

Energy system contribution in a maximal incremental test: correlations with pacing and overall performance in a 10-km running trial.

PubMed

Damasceno, M V; Pasqua, L A; Lima-Silva, A E; Bertuzzi, R

2015-11-01

This study aimed to verify the association between the contribution of energy systems during an incremental exercise test (IET), pacing, and performance during a 10-km running time trial. Thirteen male recreational runners completed an incremental exercise test on a treadmill to determine the respiratory compensation point (RCP), maximal oxygen uptake (V˙O2max), peak treadmill speed (PTS), and energy systems contribution; and a 10-km running time trial (T10-km) to determine endurance performance. The fractions of the aerobic (WAER) and glycolytic (WGLYCOL) contributions were calculated for each stage based on the oxygen uptake and the oxygen energy equivalents derived by blood lactate accumulation, respectively. Total metabolic demand (WTOTAL) was the sum of these two energy systems. Endurance performance during the T10-km was moderately correlated with RCP, V˙O2max and PTS (P<@0.05), and moderate-to-highly correlated with WAER, WGLYCOL, and WTOTAL (P<0.05). In addition, WAER, WGLYCOL, and WTOTAL were also significantly correlated with running speed in the middle (P<0.01) and final (P<0.01) sections of the T10-km. These findings suggest that the assessment of energy contribution during IET is potentially useful as an alternative variable in the evaluation of endurance runners, especially because of its relationship with specific parts of a long-distance race.

Effects of training and anthropometric factors on marathon and 100 km ultramarathon race performance

PubMed Central

Tanda, Giovanni; Knechtle, Beat

2015-01-01

Background Marathon (42 km) and 100 km ultramarathon races are increasing in popularity. The aim of the present study was to investigate the potential associations of anthropometric and training variables with performance in these long-distance running competitions. Methods Training and anthropometric data from a large cohort of marathoners and 100 km ultramarathoners provided the basis of this work. Correlations between training and anthropometric indices of subjects and race performance were assessed using bivariate and multiple regression analyses. Results A combination of volume and intensity in training was found to be suitable for prediction of marathon and 100 km ultramarathon race pace. The relative role played by these two variables was different, in that training volume was more important than training pace for the prediction of 100 km ultramarathon performance, while the opposite was found for marathon performance. Anthropometric characteristics in terms of body fat percentage negatively affected 42 km and 100 km race performance. However, when this factor was relatively low (ie, less than 15% body fat), the performance of 42 km and 100 km races could be predicted solely on the basis of training indices. Conclusion Mean weekly training distance run and mean training pace were key predictor variables for both marathon and 100 km ultramarathon race performance. Predictive correlations for race performance are provided for runners with a relatively low body fat percentage. PMID:25995653

Is the COL5A1 rs12722 gene polymorphism associated with running economy?

PubMed

Bertuzzi, Rômulo; Pasqua, Leonardo A; Bueno, Salomão; Lima-Silva, Adriano Eduardo; Matsuda, Monique; Marquezini, Monica; Saldiva, Paulo H

2014-01-01

The COL5A1 rs12722 polymorphism is considered to be a novel genetic marker for endurance running performance. It has been postulated that COL5A1 rs12722 may influence the elasticity of tendons and the energetic cost of running. To date, there are no experimental data in the literature supporting the relationship between range of motion, running economy, and the COL5A1 rs12722 gene polymorphism. Therefore, the main purpose of the current study was to analyze the influence of the COL5A1rs12722 polymorphism on running economy and range of motion. One hundred and fifty (n = 150) physically active young men performed the following tests: a) a maximal incremental treadmill test, b) two constant-speed running tests (10 km · h(-1)) and 12 km · h(-1)) to determine the running economy, and c) a sit-and-reach test to determine the range of motion. All of the subjects were genotyped for the COL5A1 rs12722 single-nucleotide polymorphism. The genotype frequencies were TT = 27.9%, CT = 55.8%, and CC = 16.3%. There were no significant differences between COL5A1 genotypes for running economy measured at 10 km · h(-1) (p = 0.232) and 12 km · h(-1) (p = 0.259). Similarly, there were no significant differences between COL5A1 genotypes for range of motion (p = 0.337). These findings suggest that the previous relationship reported between COL5A1 rs12722 genotypes and running endurance performance might not be mediated by the energetic cost of running.

Running Speed Can Be Predicted from Foot Contact Time during Outdoor over Ground Running.

PubMed

de Ruiter, Cornelis J; van Oeveren, Ben; Francke, Agnieta; Zijlstra, Patrick; van Dieen, Jaap H

2016-01-01

The number of validation studies of commercially available foot pods that provide estimates of running speed is limited and these studies have been conducted under laboratory conditions. Moreover, internal data handling and algorithms used to derive speed from these pods are proprietary and thereby unclear. The present study investigates the use of foot contact time (CT) for running speed estimations, which potentially can be used in addition to the global positioning system (GPS) in situations where GPS performance is limited. CT was measured with tri axial inertial sensors attached to the feet of 14 runners, during natural over ground outdoor running, under optimized conditions for GPS. The individual relationships between running speed and CT were established during short runs at different speeds on two days. These relations were subsequently used to predict instantaneous speed during a straight line 4 km run with a single turning point halfway. Stopwatch derived speed, measured for each of 32 consecutive 125m intervals during the 4 km runs, was used as reference. Individual speed-CT relations were strong (r2 >0.96 for all trials) and consistent between days. During the 4km runs, median error (ranges) in predicted speed from CT 2.5% (5.2) was higher (P<0.05) than for GPS 1.6% (0.8). However, around the turning point and during the first and last 125m interval, error for GPS-speed increased to 5.0% (4.5) and became greater (P<0.05) than the error predicted from CT: 2.7% (4.4). Small speed fluctuations during 4km runs were adequately monitored with both methods: CT and GPS respectively explained 85% and 73% of the total speed variance during 4km runs. In conclusion, running speed estimates bases on speed-CT relations, have acceptable accuracy and could serve to backup or substitute for GPS during tarmac running on flat terrain whenever GPS performance is limited.

Running performance and thermal sensation in the heat are improved with menthol mouth rinse but not ice slurry ingestion.

PubMed

Stevens, C J; Thoseby, B; Sculley, D V; Callister, R; Taylor, L; Dascombe, B J

2016-10-01

The purpose of this study was to compare the effects of a cooling strategy designed to predominately lower thermal state with a strategy designed to lower thermal sensation on endurance running performance and physiology in the heat. Eleven moderately trained male runners completed familiarization and three randomized, crossover 5-km running time trials on a non-motorized treadmill in hot conditions (33 °C). The trials included ice slurry ingestion before exercise (ICE), menthol mouth rinse during exercise (MEN), and no intervention (CON). Running performance was significantly improved with MEN (25.3 ± 3.5 min; P = 0.01), but not ICE (26.3 ± 3.2 min; P = 0.45) when compared with CON (26.0 ± 3.4 min). Rectal temperature was significantly decreased with ICE (by 0.3 ± 0.2 °C; P < 0.01), which persisted for 2 km of the run and MEN significantly decreased perceived thermal sensation (between 4 and 5 km) and ventilation (between 1 and 2 km) during the time trial. End-exercise blood prolactin concentration was elevated with MEN compared with CON (by 25.1 ± 24.4 ng/mL; P = 0.02). The data demonstrate that a change in the perception of thermal sensation during exercise from menthol mouth rinse was associated with improved endurance running performance in the heat. Ice slurry ingestion reduced core temperature but did not decrease thermal sensation during exercise or improve running performance. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Physiological correlates of 2-mile run performance as determined using a novel on-demand treadmill.

PubMed

Tolfrey, Keith; Hansen, Simon A; Dutton, Katie; McKee, Tom; Jones, Andrew M

2009-08-01

The purpose of this study was to assess the reproducibility of an on-demand motorised treadmill to measure 2-mile (3.2 km) race performance and to examine the physiological variables that best predict this free-running performance in active men. Twelve men (mean (SD): age, 28 (9) years; stature, 1.79 (0.05) m; body mass, 72 (9) kg) completed the study in which maximum oxygen uptake (VO2 max), running economy, and running speedin the abstract section. They appear in the rest of the paper.), running economy, and running speed at VO2 max (vVO2 max), lactate threshold (vLT), and 4 mmol.L-1 fixed blood lactate concentration (v4) were measured. Subsequently, the maximal lactate steady state (MLSS) was identified using a series of 30-min treadmill runs. Finally, each participant completed a 2-mile running performance trial on 2 separate occasions, using an on-demand treadmill that adjusts belt speed according to the participant's position on the moving belt. The average 2-mile run speed was 15.7 (SD, 1.9) km.h-1, with small individual differences between repeat-performance trials (intraclass correlation coefficient = 0.99, 95% CI 0.953 to 0.996; standard error of measurement as coefficient of variation = 1.5%, 95% CI 1.0% to 2.5%). Bivariate regression analyses identified VO2 max, vVO2 max, VO2 (mL.kg-1.min-1) at MLSS, vLT, v4, and velocity at MLSS (vMLSS) as the strongest individual predictor variables (r2 = 0.69 to 0.87; standard error of the estimate = 1.08 to 0.72 km.h-1) for 2-mile running performance. The vLT and vMLSS explained 85% and 87% of the variance in running performance, respectively, suggesting that there is considerable shared variance between these parameters. In conclusion, the on-demand treadmill system provided a reliable measure of distance running performance. Both vLT and vMLSS were strong predictors of 2-mile running performance, with vMLSS explaining marginally more of the variance.

Intensity related changes of running economy in recreational level distance runners.

PubMed

Engeroff, Tobias; Bernardi, Andreas; Niederer, Daniel; Wilke, Jan; Vogt, Lutz; Banzer, Winfried

2017-09-01

Running economy (RE) is often described as a key demand of running performance. The variety of currently used assessment methods with different running intensities and outcomes restricts interindividual comparability of RE in recreational level runners. The purpose of this study was to compare the influence of RE, assessed as oxygen cost (OC) and caloric unit cost (CUC), on running speed at individual physiological thresholds. Eighteen recreational runners performed: 1) a graded exercise test to estimate first ventilatory threshold (VT1), respiratory compensation point (RCP) and maximal oxygen uptake (VO2max); 2) discontinuous RE assessment to determine relative OC in milliliters per kilogram per kilometer (mL/kg/km) and CUC in kilocalories per kilogram per kilometer (kcal/kg/km) at three different running intensities: VT1, RCP and at a third standardized reference point (TP) in between. OC (mL/kg/km; at VT1: 235.4±26.2; at TP: 227.8±23.4; at RCP: 224.9±21.9) and CUC (kcal/kg/km at VT1: 1.18±0.13; at TP: 1.14±0.12; at RCP: 1.13±0.11) decreased with increasing intensities (P≤0.01). Controlling for the influence of sex OC and CUC linearly correlated with running speed at RCP and VO2max (P≤0.01). RE, even assessed at low intensity, is strongly related to running performance in recreational athletes. Both calculation methods used (OC and CUC) are sensitive for monitoring intensity related changes of substrate utilization. RE values decreased with higher running intensity indicating an increase of anaerobic and subsequent decrease of aerobic substrate utilization.

The effects of acute whole body vibration as a recovery modality following high-intensity interval training in well-trained, middle-aged runners.

PubMed

Edge, J; Mündel, T; Weir, K; Cochrane, D J

2009-02-01

The main purpose of the present study was to examine the effects of acute whole body vibration (WBV) on recovery following a 3 km time trial (3 km TT) and high-intensity interval training (HIIT) (8 x 400 m). Post-HIIT measures included 3 km time-trial performance, exercise metabolism and markers of muscle damage (creatine kinase, CK) and inflammation (c-reactive protein, CRP). A second purpose was to determine the effects of a 3 km TT and HIIT on performance and metabolism the following day. Nine well-trained, middle-aged, male runners [(mean +/- SD) age 45 +/- 6 years, body mass 75 +/- 7 kg, VO2peak 58 +/- 5 ml kg(-1 )min(-1)] performed a constant pace run at 60 and 80% velocity at VO2peak (v VO2peak) followed by a 3-km TT and a 8 x 400-m HIIT session on two occasions. Following one occasion, the athletes performed 2 x 15 min of low frequency (12 Hz) WBV, whilst the other occasion was a non-WBV control. Twenty-four hours after each HIIT session (day 2) participants performed the constant pace run (60 and 80% v VO2peak) and 3 km TT again. There was a significant decrease in 3 km TT performance (~10 s) 24 h after the HIIT session (P < 0.05); however, there were no differences between conditions (control vs. vibration, P > 0.05). Creatine kinase was significantly elevated on day 2, though there were no differences between conditions (P > 0.05). VO2peak and blood lactate were lower on day 2 (P < 0.05), again with no differences between conditions (P > 0.05). These results show no benefit of WBV on running performance recovery following a HIIT session. However, we have shown that there may be acute alterations in metabolism 24 h following such a running session in well-trained, middle-aged runners.

Shoe cleat position during cycling and its effect on subsequent running performance in triathletes.

PubMed

Viker, Tomas; Richardson, Matt X

2013-01-01

Research with cyclists suggests a decreased load on the lower limbs by placing the shoe cleat more posteriorly, which may benefit subsequent running in a triathlon. This study investigated the effect of shoe cleat position during cycling on subsequent running. Following bike-run training sessions with both aft and traditional cleat positions, 13 well-trained triathletes completed a 30 min simulated draft-legal triathlon cycling leg, followed by a maximal 5 km run on two occasions, once with aft-placed and once with traditionally placed cleats. Oxygen consumption, breath frequency, heart rate, cadence and power output were measured during cycling, while heart rate, contact time, 200 m lap time and total time were measured during running. Cardiovascular measures did not differ between aft and traditional cleat placement during the cycling protocol. The 5 km run time was similar for aft and traditional cleat placement, at 1084 ± 80 s and 1072 ± 64 s, respectively, as was contact time during km 1 and 5, and heart rate and running speed for km 5 for the two cleat positions. Running speed during km 1 was 2.1% ± 1.8 faster (P < 0.05) for the traditional cleat placement. There are no beneficial effects of an aft cleat position on subsequent running in a short distance triathlon.

The Relationship between Field Tests of Anaerobic Power and 10-km Run Performance.

ERIC Educational Resources Information Center

Sinnett, Aaron M.; Berg, Kris; Latin, Richard W.; Noble, John M.

2001-01-01

Investigated the relationship between several field tests of anaerobic power (e.g., +various sprints, vertical jumps, and a plyometric leap) and distance running performance in trained adult male and female runners. Results indicate that anaerobic power is significantly related to distance running performance and may explain a meaningful…

Effects of Marathon Running on Aerobic Fitness and Performance in Recreational Runners One Week after a Race.

PubMed

Takayama, Fuminori; Aoyagi, Atsushi; Shimazu, Wataru; Nabekura, Yoshiharu

2017-01-01

It is not clear whether or not recreational runners can recover aerobic fitness and performance within one week after marathon running. This study aimed to investigate the effects of running a marathon race on aerobic fitness and performance one week later. Eleven recreational runners (six men, five women) completed the race in 3 h 36 min 20 s ± 41 min 34 s (mean ± standard deviation). Before and 7 days after the race, they performed a treadmill running test. Perceived muscle soreness was assessed before the race and for the following 7 days. The magnitude of changes in the treadmill running test was considered possibly trivial for maximal oxygen uptake ([Formula: see text]O 2 max) (mean difference -1.2 ml/kg/min; ±90% confidence limits 2 ml/kg/min), unclear for %[Formula: see text]O 2 max at anaerobic threshold (AT) (-0.5; ±4.1%) and RE (0.2; ±3.5 ml/kg/km), and likely trivial for both velocity at AT and peak (-0.2; ±0.49 km/h and -0.3; ±0.28 km/h). Perceived muscle soreness increased until 3 days after the race, but there were no clear differences between the values before the race and 4-7 days after it. These results show that physiological capacity associated with marathon running performance is recovered within 7 days after a marathon run.

Effects of Marathon Running on Aerobic Fitness and Performance in Recreational Runners One Week after a Race

PubMed Central

Aoyagi, Atsushi; Shimazu, Wataru

2017-01-01

It is not clear whether or not recreational runners can recover aerobic fitness and performance within one week after marathon running. This study aimed to investigate the effects of running a marathon race on aerobic fitness and performance one week later. Eleven recreational runners (six men, five women) completed the race in 3 h 36 min 20 s ± 41 min 34 s (mean ± standard deviation). Before and 7 days after the race, they performed a treadmill running test. Perceived muscle soreness was assessed before the race and for the following 7 days. The magnitude of changes in the treadmill running test was considered possibly trivial for maximal oxygen uptake (V˙O2max) (mean difference −1.2 ml/kg/min; ±90% confidence limits 2 ml/kg/min), unclear for %V˙O2max at anaerobic threshold (AT) (−0.5; ±4.1%) and RE (0.2; ±3.5 ml/kg/km), and likely trivial for both velocity at AT and peak (−0.2; ±0.49 km/h and −0.3; ±0.28 km/h). Perceived muscle soreness increased until 3 days after the race, but there were no clear differences between the values before the race and 4–7 days after it. These results show that physiological capacity associated with marathon running performance is recovered within 7 days after a marathon run. PMID:29138757

Physical Demands in Competitive Ultimate Frisbee.

PubMed

Krustrup, Peter; Mohr, Magni

2015-12-01

The objective was to study game demands in competitive ultimate Frisbee by performing match analysis during a game. Thirteen moderately trained (Yo-Yo intermittent recovery test levels 1 and 2 [Yo-Yo IR1 and IR2] performance: 1790 ± 382 m and 657 ± 225 m, respectively) competitive male ultimate Frisbee athletes played a game in which activity profile using Global Positioning System (GPS) technology and heart rate (HR) were recorded. Game HRmean and HRpeak were 82 ± 2% and 99 ± 1% of maximum heart rate, respectively. Total game distance was 4.70 ± 0.47 km, of which 0.63 ± 0.14 km was high-intensity running and 0.21 ± 0.11 km was sprinting. In the second half, 10% less (p ≤ 0.05) ground was covered with high-intensity running compared with the first half (0.28 ± 0.08 km vs. 0.31 ± 0.07 km). Less (43-47%; p ≤ 0.05) high-intensity running was performed in the third 9-minute period of each half compared with the first two 9-minute periods of the same half. Players performed 17.4 ± 5.7 sprints during the match. Yo-Yo IR2 performance correlated to the amount of high-intensity running in the last 9 minutes of both halves (r = 0.69, p ≤ 0.05), whereas Yo-Yo IR1 performance correlated with total sprint distance (r = 0.74, p ≤ 0.05). Ultimate Frisbee is an intense intermittent team sport with high cardiovascular loading and clear indications of fatigue toward the end of each half. Yo-Yo IR test performances correlate with physical match performance.

Reliability of 5-km Running Performance in a Competitive Environment

ERIC Educational Resources Information Center

Hurst, Philip; Board, Lisa

2017-01-01

The aim of this study was to examine the reliability of a 5-km time-trial during a competitive outdoor running event. Fifteen endurance runners (age = 29.5 ± 4.3 years, height = 1.75 ± 0.08 m, body mass = 71.0 ± 7.1 kg, 5-km lifetime personal best = 19:13 ± 1:13 minutes) completed two competitive 5-km time-trials over 2 weeks. No systematic…

Age-related changes in ultra-triathlon performances

PubMed Central

2012-01-01

Background The age-related decline in performance has been investigated in swimmers, runners and triathletes. No study has investigated the age-related performance decline in ultra-triathletes. The purpose of this study was to analyse the age-related declines in swimming, cycling, running and overall race time for both Triple Iron ultra-triathlon (11.4-km swimming, 540-km cycling and 126.6-km running) and Deca Iron ultra-triathlon (38-km swimming, 1,800-km cycling and 420-km running). Methods The age and performances of 423 male Triple Iron ultra-triathletes and 119 male Deca Iron ultra-triathletes were analysed from 1992 to 2010 using regression analyses and ANOVA. Results The mean age of the finishers was significantly higher for Deca Iron ultra-triathletes (41.3 ± 3.1 years) compared to a Triple Iron ultra-triathletes (38.5 ± 3.3 years) (P < 0.05). For both ultra-distances, the fastest overall race times were achieved between the ages of 25 and 44 years. Deca Iron ultra-triathletes achieved the same level of performance in swimming and cycling between 25 and 54 years of age. Conclusions The magnitudes of age-related declines in performance in the three disciplines of ultra-triathlon differ slightly between Triple and Deca Iron ultra-triathlon. Although the ages of Triple Iron ultra-triathletes were on average younger compared to Deca Iron ultra-triathletes, the fastest race times were achieved between 25 and 44 years for both distances. Further studies should investigate the motivation and training of ultra-triathletes to gain better insights in ultra-triathlon performance. PMID:23849327

High Speed Running and Sprinting Profiles of Elite Soccer Players

PubMed Central

Miñano-Espin, Javier; Casáis, Luis; Lago-Peñas, Carlos; Gómez-Ruano, Miguel Ángel

2017-01-01

Abstract Real Madrid was named as the best club of the 20th century by the International Federation of Football History and Statistics. The aim of this study was to compare if players from Real Madrid covered shorter distances than players from the opposing team. One hundred and forty-nine matches including league, cup and UEFA Champions League matches played by the Real Madrid were monitored during the 2001-2002 to the 2006-2007 seasons. Data from both teams (Real Madrid and the opponent) were recorded. Altogether, 2082 physical performance profiles were examined, 1052 from the Real Madrid and 1031 from the opposing team (Central Defenders (CD) = 536, External Defenders (ED) = 491, Central Midfielders (CM) = 544, External Midfielders (EM) = 233, and Forwards (F) = 278). Match performance data were collected using a computerized multiple-camera tracking system (Amisco Pro®, Nice, France). A repeated measures analysis of variance (ANOVA) was performed for distances covered at different intensities (sprinting (>24.0 km/h) and high-speed running (21.1-24.0 km/h) and the number of sprints (21.1-24.0 km/h and >24.0 km/h) during games for each player sectioned under their positional roles. Players from Real Madrid covered shorter distances in high-speed running and sprint than players from the opposing team (p < 0.01). While ED did not show differences in their physical performance, CD (p < 0.05), CM (p < 0.01), EM (p < 0.01) and F (p > 0.01) from Real Madrid covered shorter distances in high-intensity running and sprint and performed less sprints than their counterparts. Finally, no differences were found in the high-intensity running and sprint distances performed by players from Real Madrid depending on the quality of the opposition. PMID:28828087

No Dose-Response Effect of Carbohydrate Mouth Rinse Concentration on 5-km Running Performance in Recreational Athletes.

PubMed

Clarke, Neil D; Thomas, James R; Kagka, Marion; Ramsbottom, Roger; Delextrat, Anne

2017-03-01

Clarke, ND, Thomas, JR, Kagka, M, Ramsbottom, R, and Delextrat, A. No dose-response effect of carbohydrate mouth rinse concentration on 5-km running performance in recreational athletes. J Strength Cond Res 31(3): 715-720, 2017-Oral carbohydrate rinsing has been demonstrated to provide beneficial effects on exercise performance of durations of up to 1 hour, albeit predominately in a laboratory setting. The aim of the present study was to investigate the effects of different concentrations of carbohydrate solution mouth rinse on 5-km running performance. Fifteen healthy men (n = 9; mean ± SD age; 42 ± 10 years; height, 177.6 ± 6.1 cm; body mass, 73.9 ± 8.9 kg) and women (n = 6; mean ± SD age, 43 ± 9 years; height, 166.5 ± 4.1 cm; body mass, 65.7 ± 6.8 kg) performed a 5-km running time trial on a track on 4 separate occasions. Immediately before starting the time trial and then after each 1 km, subjects rinsed 25 ml of 0, 3, 6, or 12% maltodextrin for 10 seconds. Mouth rinsing with 0, 3, 6, or 12% maltodextrin did not have a significant effect on the time to complete the time trial (0%, 26:34 ± 4:07 minutes:seconds; 3%, 27:17 ± 4:33 minutes:seconds; 6%, 27:05 ± 3:52 minutes:seconds; 12%, 26:47 ± 4.31 minutes:seconds; p = 0.071; (Equation is included in full-text article.)= 0.15), heart rate (p = 0.095; (Equation is included in full-text article.)= 0.16), rating of perceived exertion (p = 0.195; (Equation is included in full-text article.)= 0.11), blood glucose (p = 0.920; (Equation is included in full-text article.)= 0.01), and blood lactate concentration (p = 0.831; (Equation is included in full-text article.)= 0.02), with only nonsignificant trivial to small differences between concentrations. Results of this study suggest that carbohydrate mouth rinsing provides no ergogenic advantage over an acaloric placebo (0%) and that there is no dose-response relationship between carbohydrate solution concentration and 5-km track running performance.

No influence of ischemic preconditioning on running economy.

PubMed

Kaur, Gungeet; Binger, Megan; Evans, Claire; Trachte, Tiffany; Van Guilder, Gary P

2017-02-01

Many of the potential performance-enhancing properties of ischemic preconditioning suggest that the oxygen cost for a given endurance exercise workload will be reduced, thereby improving the economy of locomotion. The aim of this study was to identify whether ischemic preconditioning improves exercise economy in recreational runners. A randomized sham-controlled crossover study was employed in which 18 adults (age 27 ± 7 years; BMI 24.6 ± 3 kg/m 2 ) completed two, incremental submaximal (65-85% VO 2max ) treadmill running protocols (3 × 5 min stages from 7.2-14.5 km/h) coupled with indirect calorimetry to assess running economy following ischemic preconditioning (3 × 5 min bilateral upper thigh ischemia) and sham control. Running economy was expressed as mlO 2 /kg/km and as the energy in kilocalories required to cover 1 km of horizontal distance (kcal/kg/km). Ischemic preconditioning did not influence steady-state heart rate, oxygen consumption, minute ventilation, respiratory exchange ratio, energy expenditure, and blood lactate. Likewise, running economy was similar (P = 0.647) between the sham (from 201.6 ± 17.7 to 204.0 ± 16.1 mlO 2 /kg/km) and ischemic preconditioning trials (from 202.8 ± 16.2 to 203.1 ± 15.6 mlO 2 /kg/km). There was no influence (P = 0.21) of ischemic preconditioning on running economy expressed as the caloric unit cost (from 0.96 ± 0.12 to 1.01 ± 0.11 kcal/kg/km) compared with sham (from 1.00 ± 0.10 to 1.00 ± 0.08 kcal/kg/km). The properties of ischemic preconditioning thought to affect exercise performance at vigorous to severe exercise intensities, which generate more extensive physiological challenge, are ineffective at submaximal workloads and, therefore, do not change running economy.

Variability of GPS-derived running performance during official matches in elite professional soccer players.

PubMed

Al Haddad, Hani; Méndez-Villanueva, Alberto; Torreño, Nacho; Munguía-Izquierdo, Diego; Suárez-Arrones, Luis

2017-09-22

The aim of this study was to assess the match-to-match variability obtained using GPS devices, collected during official games in professional soccer players. GPS-derived data from nineteen elite soccer players were collected over two consecutive seasons. Time-motion data for players with more than five full-match were analyzed (n=202). Total distance covered (TD), TD >13-18 km/h, TD >18-21 km/h, TD >21 km/h, number of acceleration >2.5-4 m.s-2 and >4 m.s-2 were calculated. The match-to-match variation in running activity was assessed by the typical error expressed as a coefficient of variation (CV,%) and the magnitude of the CV was calculated (effect size). When all players were pooled together, CVs ranged from 5% to 77% (first half) and from 5% to 90% (second half), for TD and number of acceleration >4 m.s-2, and the magnitude of the CVs were rated from small to moderate (effect size = 0.57-0.98). The CVs were likely to increase with running/acceleration intensity, and were likely to differ between playing positions (e.g., TD > 13-18 km/h 3.4% for second strikers vs 14.2% for strikers and 14.9% for wide-defenders vs 9.7% for wide-midfielders). Present findings indicate that variability in players' running performance is high in some variables and likely position-dependent. Such variability should be taken into account when using these variables to prescribe and/or monitor training intensity/load. GPS-derived match-to-match variability in official games' locomotor performance of professional soccer players is high in some variables, particularly for high-speed running, due to the complexity of match running performance and its most influential factors and reliability of the devices.

The Running Performance Profile of Elite Gaelic Football Match-Play.

PubMed

Malone, Shane; Solan, Barry; Collins, Kieran

2017-01-01

Malone, S, Solan, B, and Collins, K. The running performance profile of elite Gaelic football match-play. J Strength Cond Res 31(1): 30-36, 2017-The current study examined (a) the match running performance of Gaelic football and (b) the decrement in match running performance with respect to position. Global positioning satellite system technologies (4-Hz; VX Sport) were used with 3 elite intercounty teams across 3 full seasons with 250 full game data sets collected. Game movements were classified according to game actions and distance covered across speed zone thresholds (total distance [TD], high-speed running distance [HSRD; ≥17 km·h], sprint distance [SD; ≥22 km·h]; accelerations [n]; peak speed [km·h]). The influence of running performance in each quarter on the subsequent quarter was analyzed across all positional roles. The mean (±SD) TD and HSRD covered during the game were 8,889 ± 1,448 m and 1,596 ± 594 m, respectively. Results show a temporal profile for TD with reductions in the second (-4.1%), third (-5.9%) and fourth (-3.8%) quarters, respectively. There was a significant reduction in HSRD in the second (-8.8%), third (-15.9%), and fourth (-19.8%) quarters when compared to the first quarter (p < 0.001). Positional differences were observed for distance-based measures with the middle 3 positions (half-back, midfield, and half-forward) completing the highest running performances. These positions also showed increased decrements in TD and HSRD and SD across quarters. The current data indicate a reduction in exercise intensity over the duration of elite Gaelic football match-play. It is unclear if this reduction is because of fatigue, pacing, contextual factors, or nutritional strategies employed by players.

Voluntary wheel running in dystrophin-deficient (mdx) mice: Relationships between exercise parameters and exacerbation of the dystrophic phenotype.

PubMed

Smythe, Gayle M; White, Jason D

2011-12-18

Voluntary wheel running can potentially be used to exacerbate the disease phenotype in dystrophin-deficient mdx mice. While it has been established that voluntary wheel running is highly variable between individuals, the key parameters of wheel running that impact the most on muscle pathology have not been examined in detail. We conducted a 2-week test of voluntary wheel running by mdx mice and the impact of wheel running on disease pathology. There was significant individual variation in the average daily distance (ranging from 0.003 ± 0.005 km to 4.48 ± 0.96 km), culminating in a wide range (0.040 km to 67.24 km) of total cumulative distances run by individuals. There was also variation in the number and length of run/rest cycles per night, and the average running rate. Correlation analyses demonstrated that in the quadriceps muscle, a low number of high distance run/rest cycles was the most consistent indicator for increased tissue damage. The amount of rest time between running bouts was a key factor associated with gastrocnemius damage. These data emphasize the need for detailed analysis of individual running performance, consideration of the length of wheel exposure time, and the selection of appropriate muscle groups for analysis, when applying the use of voluntary wheel running to disease exacerbation and/or pre-clinical testing of the efficacy of therapeutic agents in the mdx mouse.

A systematic review of the efficacy of ergogenic aids for improving running performance.

PubMed

Schubert, Matthew M; Astorino, Todd A

2013-06-01

Running is a common form of activity worldwide, and participants range from "weekend warriors" to Olympians. Unfortunately, few studies have examined efficacy of various ergogenic aids in runners because the majority of the literature consists of cycling-based protocols, which do not relate to running performance. The majority of running studies conducted markedly vary in regards to specific distance completed, subject fitness level, and effectiveness of the ergogenic aid examined. The aim of this article was to systematically examine the literature concerning utility of several ergogenic aids on middle-distance running (400-5,000 m) and long-distance running (10,000 meters marathon = 42.2 km) performance. In addition, this article highlights the dearth of running-specific studies in the literature and addresses recommendations for future research to optimize running performance through nutritional intervention. Results revealed 23 studies examining effects of various ergogenic aids on running performance, with a mean Physiotherapy Evidence Database score equal to 7.85 ± 0.70. Of these studies, 71% (n = 15) demonstrated improved running performance with ergogenic aid ingestion when compared with a placebo trial. The most effective ergogenic aids for distances from 400 m to 40 km included sodium bicarbonate (4 studies; 1.5 ± 1.1% improvement), sodium citrate (6 studies; 0.3 ± 1.7% improvement), caffeine (CAFF) (7 studies; 1.1 ± 0.4% improvement), and carbohydrate (CHO) (6 studies; 4.1 ± 4.4% improvement). Therefore, runners may benefit from ingestion of sodium bicarbonate to enhance middle distance performance and caffeine and carbohydrate to enhance performance at multiple distances.

A novel method for calculating the energy cost of turning during running

PubMed Central

Hatamoto, Yoichi; Yamada, Yosuke; Fujii, Tatsuya; Higaki, Yasuki; Kiyonaga, Akira; Tanaka, Hiroaki

2013-01-01

Although changes of direction are one of the essential locomotor patterns in ball sports, the physiological demand of turning during running has not been previously investigated. We proposed a novel approach by which to evaluate the physiological demand of turning. The purposes of this study were to establish a method of measuring the energy expenditure (EE) of a 180° turn during running and to investigate the effect of two different running speeds on the EE of a 180° turn. Eleven young, male participants performed measurement sessions at two different running speeds (4.3 and 5.4 km/hour). Each measurement session consisted of five trials, and each trial had a different frequency of turns. At both running speeds, as the turn frequency increased the gross oxygen consumption (V·O2) also increased linearly (4.3 km/hour, r = 0.973; 5.4 km/hour, r = 0.996). The V·O2 of a turn at 5.4 km/hour (0.55 [SD 0.09] mL/kg) was higher than at 4.3 km/hour (0.34 [SD 0.13] mL/kg) (P < 0.001). We conclude that the gross V·O2 of running at a fixed speed with turns is proportional to turn frequency and that the EE of a turn is different at different running speeds. The Different Frequency Accumulation Method is a useful tool for assessing the physiological demands of complex locomotor activity. PMID:24379716

The 5- or 10-km Marikenloop Run: A Prospective Study of the Etiology of Running-Related Injuries in Women.

PubMed

van der Worp, Maarten P; de Wijer, Anton; van Cingel, Robert; Verbeek, André L M; Nijhuis-van der Sanden, Maria W G; Staal, J Bart

2016-06-01

Study Design Prospective cohort. Background The popularity of running events is still growing, particularly among women; however, little is known about the risk factors for running-related injuries in female runners. Objectives The aims of this study were to determine the incidence and characteristics (site and recurrence) of running-related injuries and to identify specific risk factors for running-related injuries among female runners training for a 5- or 10-km race. Methods Four hundred thirty-five women registered for the Marikenloop run of 5 or 10 km were recruited. Follow-up data were collected over 12 weeks using questionnaires, starting 8 weeks before the event and ending 4 weeks after the event. Two orthopaedic tests (navicular drop test and extension of the first metatarsophalangeal joint) were performed in the 8 weeks before the event. Running-related injuries, defined as running-related pain of the lower back and/or the lower extremity that restricted running for at least 1 day, were assessed at 1-, 2-, and 3-month follow-ups. Results Of 417 female runners with follow-up data (96%), 93 runners (22.3%) reported 109 running-related injuries, mainly of the hip/groin, knee, and lower leg. Multivariable Cox regression analysis showed that a weekly training distance of more than 30 km (hazard ratio = 3.28; 95% confidence interval [CI]: 1.23, 8.75) and a previous running injury longer than 12 months prior (hazard ratio = 1.88; 95% CI: 1.03, 3.45) were associated with the occurrence of running-related injuries. Conclusion Hip/groin, knee, and lower-leg injuries were common among female runners. Only weekly training distance (greater than 30 km) and previous running injury (greater than 12 months prior) were associated with running-related injuries in female runners training for a 5- or 10-km event. Level of Evidence Etiology, 2b. J Orthop Sports Phys Ther 2016;46(6):462-470. Epub 26 Apr 2016. doi:10.2519/jospt.2016.6402.

The effect of breast support on upper body muscle activity during 5 km treadmill running.

PubMed

Milligan, Alexandra; Mills, Chris; Scurr, Joanna

2014-12-01

Breast support has previously been shown to influence surface EMG of the pectoralis major during running. Reductions in muscle activity have previously been associated with a reduction in energy cost, which may be advantageous for female runners. Ten female participants performed two self-paced (average pace 9 km h(-1)) 5 km treadmill runs under two breast support conditions (low and high); an additional bare-breasted 2 min run was also conducted. Surface EMG electrodes were positioned on the pectoralis major, anterior deltoid, medial deltoid, and upper trapezius, with data collected during the first 2 min of running and each kilometer interval thereafter. Reductions in peak EMG of the pectoralis major, anterior and medial deltoid were reported when participants ran in the high breast support during the initial intervals of the run (up to the second kilometer). The increased activation in the pectoralis major, anterior and medial deltoid in the low breast support may be due to increased tension within these muscles, induced by the greater breast pain experienced in the low breast support. This may be a strategy to reduce the independent breast movement causing the pain through increased muscular activation. This study further promotes the use of a high breast support during running with potential benefits for treadmill running associated with reductions in muscular demand during a 5 km run. Copyright © 2014 Elsevier B.V. All rights reserved.

Critical Velocity Is Associated With Combat-Specific Performance Measures in a Special Forces Unit.

PubMed

Hoffman, Mattan W; Stout, Jeffrey R; Hoffman, Jay R; Landua, Geva; Fukuda, David H; Sharvit, Nurit; Moran, Daniel S; Carmon, Erez; Ostfeld, Ishay

2016-02-01

The purpose of this study was to examine the relationship between critical velocity (CV) and anaerobic distance capacity (ADC) to combat-specific tasks (CST) in a special forces (SFs) unit. Eighteen male soldiers (mean ± SD; age: 19.9 ± 0.8 years; height: 177.6 ± 6.6 cm; body mass: 74.1 ± 5.8 kg; body mass index [BMI]: 23.52 ± 1.63) from an SF unit of the Israel Defense Forces volunteered to complete a 3-minute all-out run along with CST (2.5-km run, 50-m casualty carry, and 30-m repeated sprints with "rush" shooting [RPTDS]). Estimates of CV and ADC from the 3-minute all-out run were determined from data downloaded from a global position system device worn by each soldier, with CV calculated as the average velocity of the final 30 seconds of the run and ADC as the velocity-time integral above CV. Critical velocity exhibited significant negative correlations with the 2.5-km run time (r = -0.62, p < 0.01) and RPTDS time (r = -0.71, p < 0.01). In addition, CV was positively correlated with the average velocity during the 2.5-km run (r = 0.64, p < 0.01). Stepwise regression identified CV as the most significant performance measure associated with the 2.5-km run time, whereas BMI and CV measures were significant predictors of RPTDS time (R(2) = 0.67, p ≤ 0.05). Using the 3-minute all-out run as a testing measurement in combat, personnel may offer a more efficient and simpler way in assessing both aerobic and anaerobic capabilities (CV and ADC) within a relatively large sample.

Match-to-match variability in high-speed running activity in a professional soccer team.

PubMed

Carling, Christopher; Bradley, Paul; McCall, Alan; Dupont, Gregory

2016-12-01

This study investigated variability in competitive high-speed running performance in an elite soccer team. A semi-automated tracking system quantified running performance in 12 players over a season (median 17 matches per player, 207 observations). Variability [coefficient of variation (CV)] was compared for total sprint distance (TSD, >25.2 km/h), high-speed running (HSR, 19.8-25.2 km/h), total high-speed running (THSR, ≥19.8 km/h); THSR when the team was in and out of ball possession, in individual ball possession, in the peak 5 min activity period; and distance run according to individual maximal aerobic speed (MAS). Variability for % declines in THSR and distance covered at ≥80% MAS across halves, at the end of play (final 15 min vs. mean for all 15 min periods) and transiently (5 min period following peak 5 min activity period), was analysed. Collectively, variability was higher for TSD versus HSR and THSR and lowest for distance run at ≥80% MAS (CVs: 37.1%, 18.1%, 19.8% and 11.8%). THSR CVs when the team was in/out of ball possession, in individual ball possession and during the peak 5 min period were 31.5%, 26.1%, 60.1% and 23.9%. Variability in THSR declines across halves, at the end of play and transiently, ranged from 37.1% to 142.6%, while lower CVs were observed in these metrics for running at ≥80% MAS (20.9-53.3%).These results cast doubt on the appropriateness of general measures of high-speed activity for determining variability in an elite soccer team, although individualisation of HSR thresholds according to fitness characteristics might provide more stable indicators of running performance and fatigue occurrence.

Relationship of running intensity to hypertension, hypercholesterolemia, and diabetes.

PubMed

Williams, Paul T

2008-10-01

To estimate the independent relationships of running intensity with antihypertensive, LDL-cholesterol-lowering, and antidiabetic medication use when adjusted for running volume (km x d(-1)). Self-reported medication use was compared cross-sectionally to running pace (m x s(-1) during usual run) in 25,552 male and 29,148 female National Runners' Health Study participants. The men ran a mean +/- SD of 5.2 +/- 3.1 km x d(-1) at 3.3 +/- 0.5 m x s(-1) (8.3 +/- 1.4 min x mile(-1)) and the women 4.7 +/- 2.9 km x wk(-1) at 3.0 +/- 0.4 m x s(-1) (9.2 +/- 1.8 min x mile(-1)). When adjusted for kilometers per day, each meter-per-second increment in intensity in men and women reduced the odds for antihypertensive drug use by 54% and 46%, respectively, reduced the odds for LDL-cholesterol-lowering medication use by 55% and 48%, respectively, and reduced the odds for antidiabetic medication use by 50% and 75%, respectively (all P < 0.0001). Compared with men who ran slower than 10 min x mile(-1), the odds for medication use in those who ran or exceeded a 7-min x mile(-1) pace were 72% less for antihypertensive, 78% less for LDL-cholesterol lowering, and 67% less for antidiabetic medications (the corresponding odds reductions in women were 61%, 64%, and 87%, respectively, for 8 min x mile(-1) or faster versus slower than 11 min x mile(-1)). Although usual running pace correlated significantly with a 10-km performance (male, r = 0.55; females, r = 0.49), usual pace remained significantly related to lower use of all three medications in men and antihypertension and antidiabetic medications in women when adjusted for a 10-km performance. Although these results do not prove causality, they show that exercise intensity is inversely associated with the prevalence of hypertension, hypercholesterolemia, and diabetes independent of exercise volume and cardiorespiratory fitness (10-km performance), suggesting that the more vigorous the exercise, the healthier the health benefits.

Validity of the Apple iPhone® /iPod Touch® as an accelerometer-based physical activity monitor: a proof-of-concept study.

PubMed

Nolan, Meaghan; Mitchell, J Ross; Doyle-Baker, Patricia K

2014-05-01

The popularity of smartphones has led researchers to ask if they can replace traditional tools for assessing free-living physical activity. Our purpose was to establish proof-of-concept that a smartphone could record acceleration during physical activity, and those data could be modeled to predict activity type (walking or running), speed (km·h-1), and energy expenditure (METs). An application to record and e-mail accelerations was developed for the Apple iPhone®/iPod Touch®. Twenty-five healthy adults performed treadmill walking (4.0 km·h-1 to 7.2 km·h-1) and running (8.1 km·h-1 to 11.3 km·h-1) wearing the device. Criterion energy expenditure measurements were collected via metabolic cart. Activity type was classified with 99% accuracy. Speed was predicted with a bias of 0.02 km·h-1 (SEE: 0.57 km·h-1) for walking, -0.03 km·h-1 (SEE: 1.02 km·h-1) for running. Energy expenditure was predicted with a bias of 0.35 METs (SEE: 0.75 METs) for walking, -0.43 METs (SEE: 1.24 METs) for running. Our results suggest that an iPhone/iPod Touch can predict aspects of locomotion with accuracy similar to other accelerometer-based tools. Future studies may leverage this and the additional features of smartphones to improve data collection and compliance.

Defining the determinants of endurance running performance in the heat

PubMed Central

James, Carl A.; Hayes, Mark; Willmott, Ashley G. B.; Gibson, Oliver R.; Schlader, Zachary J.; Maxwell, Neil S.

2017-01-01

ABSTRACT In cool conditions, physiologic markers accurately predict endurance performance, but it is unclear whether thermal strain and perceived thermal strain modify the strength of these relationships. This study examined the relationships between traditional determinants of endurance performance and time to complete a 5-km time trial in the heat. Seventeen club runners completed graded exercise tests (GXT) in hot (GXTHOT; 32°C, 60% RH, 27.2°C WBGT) and cool conditions (GXTCOOL; 13°C, 50% RH, 9.3°C WBGT) to determine maximal oxygen uptake (V̇O2max), running economy (RE), velocity at V̇O2max (vV̇O2max), and running speeds corresponding to the lactate threshold (LT, 2 mmol.l−1) and lactate turnpoint (LTP, 4 mmol.l−1). Simultaneous multiple linear regression was used to predict 5 km time, using these determinants, indicating neither GXTHOT (R2 = 0.72) nor GXTCOOL (R2 = 0.86) predicted performance in the heat as strongly has previously been reported in cool conditions. vV̇O2max was the strongest individual predictor of performance, both when assessed in GXTHOT (r = −0.83) and GXTCOOL (r = −0.90). The GXTs revealed the following correlations for individual predictors in GXTHOT; V̇O2max r = −0.7, RE r = 0.36, LT r = −0.77, LTP r = −0.78 and in GXTCOOL; V̇O2max r = −0.67, RE r = 0.62, LT r = −0.79, LTP r = −0.8. These data indicate (i) GXTHOT does not predict 5 km running performance in the heat as strongly as a GXTCOOL, (ii) as in cool conditions, vV̇O2max may best predict running performance in the heat. PMID:28944273

Strenuous running exacerbates knee cartilage erosion induced by low amount of mono-iodoacetate in rats.

PubMed

Saito, Ryusuke; Muneta, Takeshi; Ozeki, Nobutake; Nakagawa, Yusuke; Udo, Mio; Yanagisawa, Katsuaki; Tsuji, Kunikazu; Tomita, Makoto; Koga, Hideyuki; Sekiya, Ichiro

2017-01-25

It is still debated whether strenuous running in the inflammatory phase produces beneficial or harmful effect in rat knees. We examined (1) the dropout rate of rats during a 30-km running protocol, (2) influences of strenuous running and/or low amounts of mono-iodoacetate injection on cartilage, and (3) the effect of strenuous running on synovitis. Rats were forced to run 30 km over 6 weeks and the dropout rate was examined. One week after 0.1 mg mono-iodoacetate was injected into the right knee, rats were forced to run either 15 km or not run at all over 3 weeks, after which knee cartilage was evaluated. Synovium at the infrapatellar fat pad was also examined histologically. Even though all 12 rats run up to 15 km, only 6 rats completed 30 km of running. Macroscopically, 0.1 mg mono-iodoacetate induced erosion at the tibial cartilage irrespective of 15 km of running. Histologically, 0.1 mg mono-iodoacetate induced loss of cartilage matrix in the tibial cartilage, and an additional 15 km of strenuous running significantly exacerbated the loss. Synovitis caused by mono-iodoacetate improved after running. Only 50% of rats completed 30 km of running because of foot problems. Strenuous running further exacerbated tibial cartilage erosion but did not influence synovitis induced by mono-iodoacetate.

Beneficial effects of voluntary wheel running on the properties of dystrophic mouse muscle.

PubMed

Hayes, A; Williams, D A

1996-02-01

Effects of voluntary exercise on the isometric contractile, fatigue, and histochemical properties of hindlimb dystrophic (mdx and 129ReJ dy/dy) skeletal muscles were investigated. Mice were allowed free access to a voluntary running wheel at 4 wk of age for a duration of 16 (mdx) or 5 (dy/dy) wk. Running performance of mdx mice (approximately 4 km/day at 1.6 km/h) was inferior to normal mice (approximately 6.5 km/day at 2.1 km/h). However, exercise improved the force output (approximately 15%) and the fatigue resistance of both C57BL/10 and mdx soleus muscles. These changes coincided with increased proportions of smaller type I fibers and decreased proportions of larger type IIa fibers in the mdx soleus. The extensor digitorum longus of mdx, but not of normal, mice also exhibited improved resistance to fatigue and conversion towards oxidative fiber types. The dy/dy animals were capable of exercising, yet ran significantly less than normal animals (approximately 0.5 km/day). Despite this, running increased the force output of the plantaris muscle (approximately 50%). Taken together, the results showed that exercise can have beneficial effects on dystrophic skeletal muscles.

Physiological and biomechanical adaptations to the cycle to run transition in Olympic triathlon: review and practical recommendations for training.

PubMed

Millet, G P; Vleck, V E

2000-10-01

Current knowledge of the physiological, biomechanical, and sensory effects of the cycle to run transition in the Olympic triathlon (1.5 km, 10 km, 40 km) is reviewed and implications for the training of junior and elite triathletes are discussed. Triathlon running elicits hyperventilation, increased heart rate, decreased pulmonary compliance, and exercise induced hypoxaemia. This may be due to exercise intensity, ventilatory muscle fatigue, dehydration, muscle fibre damage, a shift in metabolism towards fat oxidation, and depleted glycogen stores after a 40 km cycle. The energy cost (CR) of running during the cycle to run transition is also increased over that of control running. The increase in CR varies from 1.6% to 11.6% and is a reflection of triathlete ability level. This increase may be partly related to kinematic alterations, but research suggests that most biomechanical parameters are unchanged. A more forward leaning trunk inclination is the most significant observation reported. Running pattern, and thus running economy, could also be influenced by sensorimotor perturbations related to the change in posture. Technical skill in the transition area is obviously very important. The conditions under which the preceding cycling section is performed-that is, steady state or stochastic power output, drafting or non-drafting-are likely to influence the speed of adjustment to transition. The extent to which a decrease in the average 10 km running speed occurs during competition must be investigated further. It is clear that the higher the athlete is placed in the field at the end of the bike section, the greater the importance to their finishing position of both a quick transition area time and optimal adjustment to the physiological demands of the cycle to run transition. The need for, and current methods of, training to prepare junior and elite triathletes for a better transition are critically reviewed in light of the effects of sequential cycle to run exercise.

Age and ultra-marathon performance - 50 to 1,000 km distances from 1969 - 2012.

PubMed

Romer, Tobias; Rüst, Christoph Alexander; Zingg, Matthias Alexander; Rosemann, Thomas; Knechtle, Beat

2014-01-01

We investigated age and performance in distance-limited ultra-marathons held from 50 km to 1,000 km. Age of peak running speed and running speed of the fastest competitors from 1969 to 2012 in 50 km, 100 km, 200 km and 1,000 km ultra-marathons were analyzed using analysis of variance and multi-level regression analyses. The ages of the ten fastest women ever were 40 ± 4 yrs (50 km), 34 ± 7 yrs (100 km), 42 ± 6 yrs (200 km), and 41 ± 5 yrs (1,000 km). The ages were significantly different between 100 km and 200 km and between 100 km and 1,000 km. For men, the ages of the ten fastest ever were 34 ± 6 yrs (50 km), 32 ± 4 yrs (100 km), 44 ± 4 yrs (200 km), and 47 ± 9 yrs (1,000 km). The ages were significantly younger in 50 km compared to 100 km and 200 km and also significantly younger in 100 km compared to 200 km and 1,000 km. The age of the annual ten fastest women decreased in 50 km from 39 ± 8 yrs (1988) to 32 ± 4 yrs (2012) and in men from 35 ± 5 yrs (1977) to 33 ± 5 yrs (2012). In 100 km events, the age of peak running speed of the annual ten fastest women and men remained stable at 34.9 ± 3.2 and 34.5 ± 2.5 yrs, respectively. Peak running speed of top ten runners increased in 50 km and 100 km in women (10.6 ± 1.0 to 15.3 ± 0.7 km/h and 7.3 ± 1.5 to 13.0 ± 0.2 km/h, respectively) and men (14.3 ± 1.2 to 17.5 ± 0.6 km/h and 10.2 ± 1.2 to 15.1 ± 0.2 km/h, respectively). In 200 km and 1,000 km, running speed remained unchanged. In summary, the best male 1,000 km ultra-marathoners were ~15 yrs older than the best male 100 km ultra-marathoners and the best female 1,000 km ultra-marathoners were ~7 yrs older than the best female 100 km ultra-marathoners. The age of the fastest 50 km ultra-marathoners decreased across years whereas it remained unchanged in 100 km ultra-marathoners. These findings may help athletes and coaches to plan an ultra-marathoner's career. Future studies are needed on the mechanisms by which the fastest runners in the long ultra-marathons tend to be older than those in shorter ultra-marathons.

Betalain-rich concentrate supplementation improves exercise performance and recovery in competitive triathletes.

PubMed

Montenegro, Cristhian F; Kwong, David A; Minow, Zev A; Davis, Brian A; Lozada, Christina F; Casazza, Gretchen A

2017-02-01

We aimed to determine the effects of a betalain-rich concentrate (BRC) of beetroots, containing no sugars or nitrates, on exercise performance and recovery. Twenty-two (9 men and 13 women) triathletes (age, 38 ± 11 years) completed 2 double-blind, crossover, randomized trials (BRC and placebo) starting 7 days apart. Each trial was preceded by 6 days of supplementation with 100 mg·day -1 of BRC or placebo. On the 7th day of supplementation, exercise trials commenced 120 min after ingestion of 50 mg BRC or placebo and consisted of 40 min of cycling (75 ± 5% maximal oxygen consumption) followed by a 10-km running time trial (TT). Subjects returned 24 h later to complete a 5-km running TT to assess recovery. Ten-kilometer TT duration (49.5 ± 8.9 vs. 50.8 ± 10.3 min, p = 0.03) was faster with the BRC treatment. Despite running faster, average heart rate and ratings of perceived exertion were not different between treatments. Five-kilometer TT duration (23.2 ± 4.4 vs 23.9 ± 4.7 min, p = 0.003), 24 h after the 10-km TT, was faster in 17 of the 22 subjects with the BRC treatment. Creatine kinase, a muscle damage marker, increased less (40.5 ± 22.5 vs. 49.7 ± 21.5 U·L -1 , p = 0.02) from baseline to after the 10-km TT and subjective fatigue increased less (-0.05 ± 6.1 vs. 3.23 ± 6.1, p = 0.05) from baseline to 24 h after the 10-km TT with BRC. In conclusion, BRC supplementation improved 10-km TT performance in competitive male and female triathletes. Improved 5-km TT performances 24 h after the 10-km TT and the attenuated increase of creatine kinase and fatigue suggest an increase in recovery while taking BRC.

Gait-cycle characteristics and running economy in elite Eritrean and European runners.

PubMed

Santos-Concejero, Jordan; Oliván, Jesús; Maté-Muñoz, José L; Muniesa, Carlos; Montil, Marta; Tucker, Ross; Lucia, Alejandro

2015-04-01

This study aimed to determine whether biomechanical characteristics such as ground-contact time, swing time, and stride length and frequency contribute to the exceptional running economy of East African runners. Seventeen elite long-distance runners (9 Eritrean, 8 European) performed an incremental maximal running test and 3 submaximal running bouts at 17, 19, and 21 km/h. During the tests, gas-exchange parameters were measured to determine maximal oxygen uptake (VO2max) and running economy (RE). In addition, ground-contact time, swing time, stride length, and stride frequency were measured. The European runners had higher VO2max values than the Eritrean runners (77.2 ± 5.2 vs 73.5 ± 6.0 mL · kg-1 · min-1, P = .011, effect sizes [ES] = 0.65), although Eritrean runners were more economical at 19 km/h (191.4 ± 10.4 vs 205.9 ± 13.3 mL · kg-1 · min-1, P = .026, ES = 1.21). There were no differences between groups for ground-contact time, swing time, stride length, or stride frequency at any speed. Swing time was associated with running economy at 21 km/h in the Eritrean runners (r = .71, P = .033), but no other significant association was found between RE and biomechanical variables. Finally, best 10-km performance was significantly correlated with RE (r = -.57; P = .013). Eritrean runners have superior RE compared with elite European runners. This appears to offset their inferior VO2max. However, the current data suggest that their better RE does not have a biomechanical basis. Other factors, not measured in the current study, may contribute to this RE advantage.

Changes in skeletal and cardiac muscle enzymes during the Scottish Coast to Coast Triathlon.

PubMed

Denvir, M A; Galloway, P J; Meighan, A S; Blyth, M; Alexander, C; Fleming, C; Frame, F

1999-04-01

While skeletal muscle injury is common after prolonged exercise, evidence in the literature supporting cardiac muscle injury is conflicting. Creatine kinase and cardiac troponin-I were measured, in 31 amateur athletes (25 male) before, and 12-24 hours after, a 300 km cycling/running/canoe triathlon event. A short questionnaire was used to assess level of fitness, training and previous experience. Creatine kinase levels were greater after the 45 km cross-country run compared with after a 155 km road cycle (60.5 +/- 62.8 iu/L/kg vs 19.3 +/- 9.6 iu/kg, P = 0.03). Individuals performing running and cycling events consecutively had creatine kinase similar to those observed after running alone (50.2 +/- 53.8 iu/L/kg vs 60.5 +/- 62.8 iu/L/kg, P = 0.55). Cardiac troponin-I was elevated above the normal range (0.1 ng/L) in six athletes (four in running and cycling events, one in the running and one in the cycling event). We conclude that running produces significantly more skeletal muscle injury than cycling and that strenuous endurance exercise involving running and cycling in amateur trained athletes is associated with release of cardiac specific enzymes. The functional and longer term consequences of this require further study.

Evolution of perceived footwear comfort over a prolonged running session.

PubMed

Hintzy, F; Cavagna, J; Horvais, N

2015-12-01

The purpose of this study was to investigate the subjective perception of overall footwear comfort over a prolonged running session. Ten runners performed two similar sessions consisting of a 13-km trail run (5 laps of 2.6 km) as fast as possible. The overall footwear comfort was evaluated before running and at the end of each lap with a 150-mm visual analogic scale, as well as speed, heart rate and rate of perceived exertion. The results showed that both overall footwear comfort and speed decreased consistently during the run session, and significantly after 44 min of running (i.e. the 3rd lap). It could be hypothesized that the deterioration of overall footwear comfort was explained by mechanical and energetical parameter changes with time and/or fatigue occurring at the whole body, foot and footwear levels. These results justify the use of a prolonged running test for running footwear comfort evaluation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of environmental temperature on duathlon performance.

PubMed

Sparks, S A; Cable, N T; Doran, D A; Maclaren, D P M

The aim of this study was to evaluate the physiological, metabolic and performance responses to duathlon performance under a range of ambient temperatures. Ten male recreational athletes performed three self-paced duathlon time trials consisting of a 5 km run (R1), a 30 km cycle and a 5 km run (R2) at 10 degrees C, 20 degrees C and 30 degrees C and a relative humidity of 50%. Performance times, heart rate (HR), rating of perceived exertion (RPE), core temperature (Tc) and skin temperature (Tsk) were measured every kilometre. Carbohydrate and fat oxidation rates were calculated via expired gas analysis at the first and fourth kilometres during both running stages. Blood samples were taken before and after exercise for the determination of prolactin concentration.Overall performance was significantly faster at 10 degrees C (100.76+/-5.32 min) than at 30 degrees C (105.38 +/- 4.28 min). Significantly higher Tc was noted in the 30 degrees C trial than in the 10 degrees C trial, with concomitant elevations in prolactin after exercise (19.88 +/- 6.48 ng/ml at 30 degrees C; 13.10 +/- 8.75 ng/ml at 10 degrees C). The rates of carbohydrate oxidation did not differ between conditions, although fat oxidation rates were highest at 10 degrees C. Elevated ambient temperature has a negative effect on duathlon performance. This effect may be reflected in increased Tc and prolactin concentration.

The effect of pre-test carbohydrate ingestion on the anaerobic threshold, as determined by the lactate-minimum test.

PubMed

Rotstein, Arie; Dotan, Raffy; Zigel, Levana; Greenberg, Tally; Benyamini, Yael; Falk, Bareket

2007-12-01

The purpose of this study was to investigate the effect of pre-test carbohydrate (CHO) ingestion on anaerobic-threshold assessment using the lactate-minimum test (LMT). Fifteen competitive male distance runners capable of running 10 km in 33.5-43 min were used as subjects. LMT was performed following CHO (2x300 mL, 7% solution) or comparable placebo (Pl) ingestion, in a double-blind, randomized order. The LMT consisted of two high-intensity 1 min treadmill runs (17-21 km.h(-1)), followed by an 8 min recovery period. Subsequently, subjects performed 5 min running stages, incremented by 0.6 km.h(-1) and separated by 1 min blood-sampling intervals. Tests were terminated after 3 consecutive increases in blood-lactate concentration ([La]) had been observed. Finger-tip capillary blood was sampled for [La] and blood-glucose determination 30 min before the test's onset, during the recovery phase following the 2 high-intensity runs, and following each of the subsequent 5 min stages. Heart rate (HR) and rating of perceived exertion (RPE) were recorded after each stage. The lactate-minimum speed (LMS) was determined from the individual [La]-velocity plots and was considered reflective of the anaerobic threshold. Pre-test CHO ingestion had no effect on LMS (13.19+/-1.12 km.h(-1) vs. 13.17+/-1.08 km.h(-1) in CHO and Pl, respectively), nor on [La] and glucose concentration at that speed, or on HR and RPE responses. Pre-test CHO ingestion therefore does not affect LMS or the LMT-estimated anaerobic threshold.

Physiological and biomechanical adaptations to the cycle to run transition in Olympic triathlon: review and practical recommendations for training

PubMed Central

Millet, G.; Vleck, V.

2000-01-01

Current knowledge of the physiological, biomechanical, and sensory effects of the cycle to run transition in the Olympic triathlon (1.5 km, 10 km, 40 km) is reviewed and implications for the training of junior and elite triathletes are discussed. Triathlon running elicits hyperventilation, increased heart rate, decreased pulmonary compliance, and exercise induced hypoxaemia. This may be due to exercise intensity, ventilatory muscle fatigue, dehydration, muscle fibre damage, a shift in metabolism towards fat oxidation, and depleted glycogen stores after a 40 km cycle. The energy cost (CR) of running during the cycle to run transition is also increased over that of control running. The increase in CR varies from 1.6% to 11.6% and is a reflection of triathlete ability level. This increase may be partly related to kinematic alterations, but research suggests that most biomechanical parameters are unchanged. A more forward leaning trunk inclination is the most significant observation reported. Running pattern, and thus running economy, could also be influenced by sensorimotor perturbations related to the change in posture. Technical skill in the transition area is obviously very important. The conditions under which the preceding cycling section is performed—that is, steady state or stochastic power output, drafting or non-drafting—are likely to influence the speed of adjustment to transition. The extent to which a decrease in the average 10 km running speed occurs during competition must be investigated further. It is clear that the higher the athlete is placed in the field at the end of the bike section, the greater the importance to their finishing position of both a quick transition area time and optimal adjustment to the physiological demands of the cycle to run transition. The need for, and current methods of, training to prepare junior and elite triathletes for a better transition are critically reviewed in light of the effects of sequential cycle to run exercise. Key Words: triathlon; cycle to run transition; training; performance PMID:11049151

Effect of speed endurance training and reduced training volume on running economy and single muscle fiber adaptations in trained runners.

PubMed

Skovgaard, Casper; Christiansen, Danny; Christensen, Peter M; Almquist, Nicki W; Thomassen, Martin; Bangsbo, Jens

2018-02-01

The aim of the present study was to examine whether improved running economy with a period of speed endurance training and reduced training volume could be related to adaptations in specific muscle fibers. Twenty trained male (n = 14) and female (n = 6) runners (maximum oxygen consumption (VO 2 -max): 56.4 ± 4.6 mL/min/kg) completed a 40-day intervention with 10 sessions of speed endurance training (5-10 × 30-sec maximal running) and a reduced (36%) volume of training. Before and after the intervention, a muscle biopsy was obtained at rest, and an incremental running test to exhaustion was performed. In addition, running at 60% vVO 2 -max, and a 10-km run was performed in a normal and a muscle slow twitch (ST) glycogen-depleted condition. After compared to before the intervention, expression of mitochondrial uncoupling protein 3 (UCP3) was lower (P < 0.05) and dystrophin was higher (P < 0.05) in ST muscle fibers, and sarcoplasmic reticulum calcium ATPase 1 (SERCA1) was lower (P < 0.05) in fast twitch muscle fibers. Running economy at 60% vVO 2 -max (11.6 ± 0.2 km/h) and at v10-km (13.7 ± 0.3 km/h) was ~2% better (P < 0.05) after the intervention in the normal condition, but unchanged in the ST glycogen-depleted condition. Ten kilometer performance was improved (P < 0.01) by 3.2% (43.7 ± 1.0 vs. 45.2 ± 1.2 min) and 3.9% (45.8 ± 1.2 vs. 47.7 ± 1.3 min) in the normal and the ST glycogen-depleted condition, respectively. VO 2 -max was the same, but vVO 2 -max was 2.0% higher (P < 0.05; 19.3 ± 0.3 vs. 18.9 ± 0.3 km/h) after than before the intervention. Thus, improved running economy with intense training may be related to changes in expression of proteins linked to energy consuming processes in primarily ST muscle fibers. © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

What predicts performance in ultra-triathlon races? – a comparison between Ironman distance triathlon and ultra-triathlon

PubMed Central

Knechtle, Beat; Zingg, Matthias Alexander; Rosemann, Thomas; Stiefel, Michael; Rüst, Christoph Alexander

2015-01-01

Objective This narrative review summarizes recent intentions to find potential predictor variables for ultra-triathlon race performance (ie, triathlon races longer than the Ironman distance covering 3.8 km swimming, 180 km cycling, and 42.195 km running). Results from studies on ultra-triathletes were compared to results on studies on Ironman triathletes. Methods A literature search was performed in PubMed using the terms “ultra”, “triathlon”, and “performance” for the aspects of “ultra-triathlon”, and “Ironman”, “triathlon”, and “performance” for the aspects of “Ironman triathlon”. All resulting papers were searched for related citations. Results for ultra-triathlons were compared to results for Ironman-distance triathlons to find potential differences. Results Athletes competing in Ironman and ultra-triathlon differed in anthropometric and training characteristics, where both Ironmen and ultra-triathletes profited from low body fat, but ultra-triathletes relied more on training volume, whereas speed during training was related to Ironman race time. The most important predictive variables for a fast race time in an ultra-triathlon from Double Iron (ie, 7.6 km swimming, 360 km cycling, and 84.4 km running) and longer were male sex, low body fat, age of 35–40 years, extensive previous experience, a fast time in cycling and running but not in swimming, and origins in Central Europe. Conclusion Any athlete intending to compete in an ultra-triathlon should be aware that low body fat and high training volumes are highly predictive for overall race time. Little is known about the physiological characteristics of these athletes and about female ultra-triathletes. Future studies need to investigate anthropometric and training characteristics of female ultra-triathletes and what motivates women to compete in these races. Future studies need to correlate physiological characteristics such as maximum oxygen uptake (VO2max) with ultra-triathlon race performance in order to investigate whether these characteristics are also predictive for ultra-triathlon race performance. PMID:26056498

Endurance Running Training Individually-Guided By Hrv In Untrained Women.

PubMed

da Silva, Danilo F; Ferraro, Zachary M; Adamo, Kristi B; Machado, Fabiana A

2017-05-30

The aim of this study was to analyze the effects of HRV-guided training compared to a standardized prescription on i) time to complete 5-km running performance (t5km), ii) peak treadmill running speed (Vpeak) and its time limit (tlim at Vpeak), and iii) autonomic cardiac modulation (i.e., parasympathetic activity and recovery) in untrained women. Additionally, we correlated changes in t5km with changes in Vpeak, tlim at Vpeak and autonomic cardiac modulation. Thirty-six untrained women were divided into a HRV-guided training group (HRVG) and a control group (CG). The CG followed a pre-defined program, alternating moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). The determination of MICT or HIIT was based on the pre-training HRV for HRVG. MICT was performed if HRV was < mean - 1 SD of previous measures. Otherwise, HIIT was prescribed. The t5km, Vpeak, tlim at Vpeak, parasympathetic activity (i.e., rMSSD) and parasympathetic reactivation (i.e., HRR) were measured before and after the training period. The t5km decreased to a greater magnitude in the HRVG (-17.5±5.6% vs. -14±4.7%; Effect Size (ES) between-group difference=moderate). rMSSD and tlim at Vpeak only improved in HRVG (+23.3±27.8% and +23.6±31.9%, respectively). The HRVG experienced greater improvements in Vpeak and HRR (Vpeak: 10±7.3% vs. 8.2±4.7%; HRR: 19.1±28.1% vs. 12.6±12.9%; ES between-group difference=small). Although HRVG performed less MICT than CG, the volume of MICT was negatively related to changes in t5km. Vpeak changes were highly correlated with t5km changes. The greater improvements in HRVG for t5km and autonomic modulation reinforce the potential application of this tool.

Effects of endurance training and competition on exercise tests in relatively untrained people.

PubMed

Verstappen, F T; Janssen, G M; Does, R J

1989-10-01

One hundred fourteen subjects (34 +/- 8 years) without any competition background took part in an endurance training study to be completed after 1.5 years with running a marathon. Ultimately, 60 males and 18 females achieved that goal. The training program, carefully supervised, was divided into three phases with a maximum of 45, 70, and 110 km/week training volume and concluded with a performance race of 15, 25, and 42.195 km, respectively. Three days before and 3 and 5 days after each race, 35 subjects were selected to perform a progressive treadmill test and the remaining subjects participated in performing field tests of running 400 and 1000 m. The maximal velocity achieved in the treadmill test was 4.75 +/- 0.36 m.s-1 for males and 4.18 +/- 0.28 m.s-1 for females; it remained constant throughout the study. However, the running velocity at 4 mmol.1(-1) plasma lactate concentration increased about 10% from phase 1 to 3. In the females this rise already appeared to be completed in phase 2. Heart rate showed a tendency to increase at both submaximal and maximal exercise from training phase 1 to 2 and 3, whereas plasma lactate concentration showed a decreasing tendency. Three days after the 25 km and the marathon race the maximal running velocity in the exercise test was 2%-4% lower compared with the pre-race test (P less than 0.05). Five days after the race this difference again faded away. This small decline in running performance was not reflected in changes of physiologic responses such as heart rate or plasma lactate concentration.

Lower-volume muscle-damaging exercise protects against high-volume muscle-damaging exercise and the detrimental effects on endurance performance.

PubMed

Burt, Dean; Lamb, Kevin; Nicholas, Ceri; Twist, Craig

2015-07-01

This study examined whether lower-volume exercise-induced muscle damage (EIMD) performed 2 weeks before high-volume muscle-damaging exercise protects against its detrimental effect on running performance. Sixteen male participants were randomly assigned to a lower-volume (five sets of ten squats, n = 8) or high-volume (ten sets of ten squats, n = 8) EIMD group and completed baseline measurements for muscle soreness, knee extensor torque, creatine kinase (CK), a 5-min fixed-intensity running bout and a 3-km running time-trial. Measurements were repeated 24 and 48 h after EIMD, and the running time-trial after 48 h. Two weeks later, both groups repeated the baseline measurements, ten sets of ten squats and the same follow-up testing (Bout 2). Data analysis revealed increases in muscle soreness and CK and decreases in knee extensor torque 24-48 h after the initial bouts of EIMD. Increases in oxygen uptake [Formula: see text], minute ventilation [Formula: see text] and rating of perceived exertion were observed during fixed-intensity running 24-48 h after EIMD Bout 1. Likewise, time increased and speed and [Formula: see text] decreased during a 3-km running time-trial 48 h after EIMD. Symptoms of EIMD, responses during fixed-intensity and running time-trial were attenuated in the days after the repeated bout of high-volume EIMD performed 2 weeks after the initial bout. This study demonstrates that the protective effect of lower-volume EIMD on subsequent high-volume EIMD is transferable to endurance running. Furthermore, time-trial performance was found to be preserved after a repeated bout of EIMD.

The Effects of a Duathlon Simulation on Ventilatory Threshold and Running Economy

PubMed Central

Berry, Nathaniel T.; Wideman, Laurie; Shields, Edgar W.; Battaglini, Claudio L.

2016-01-01

Multisport events continue to grow in popularity among recreational, amateur, and professional athletes around the world. This study aimed to determine the compounding effects of the initial run and cycling legs of an International Triathlon Union (ITU) Duathlon simulation on maximal oxygen uptake (VO2max), ventilatory threshold (VT) and running economy (RE) within a thermoneutral, laboratory controlled setting. Seven highly trained multisport athletes completed three trials; Trial-1 consisted of a speed only VO2max treadmill protocol (SOVO2max) to determine VO2max, VT, and RE during a single-bout run; Trial-2 consisted of a 10 km run at 98% of VT followed by an incremental VO2max test on the cycle ergometer; Trial-3 consisted of a 10 km run and 30 km cycling bout at 98% of VT followed by a speed only treadmill test to determine the compounding effects of the initial legs of a duathlon on VO2max, VT, and RE. A repeated measures ANOVA was performed to determine differences between variables across trials. No difference in VO2max, VT (%VO2max), maximal HR, or maximal RPE was observed across trials. Oxygen consumption at VT was significantly lower during Trial-3 compared to Trial-1 (p = 0.01). This decrease was coupled with a significant reduction in running speed at VT (p = 0.015). A significant interaction between trial and running speed indicate that RE was significantly altered during Trial-3 compared to Trial-1 (p < 0.001). The first two legs of a laboratory based duathlon simulation negatively impact VT and RE. Our findings may provide a useful method to evaluate multisport athletes since a single-bout incremental treadmill test fails to reveal important alterations in physiological thresholds. Key points Decrease in relative oxygen uptake at VT (ml·kg-1·min-1) during the final leg of a duathlon simulation, compared to a single-bout maximal run. We observed a decrease in running speed at VT during the final leg of a duathlon simulation; resulting in an increase of more than 2 minutes to complete a 5 km run. During our study, highly trained athletes were unable to complete the final 5 km run at the same intensity that they completed the initial 10 km run (in a laboratory setting). A better understanding, and determination, of training loads during multisport training may help to better periodize training programs; additional research is required. PMID:27274661

What is associated with race performance in male 100-km ultra-marathoners--anthropometry, training or marathon best time?

PubMed

Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Senn, Oliver

2011-03-01

We investigated the associations of anthropometry, training, and pre-race experience with race time in 93 recreational male ultra-marathoners (mean age 44.6 years, s = 10.0; body mass 74.0 kg, s = 9.0; height 1.77 m, s = 0.06; body mass index 23.4 kg · m(-2), s = 2.0) in a 100-km ultra-marathon using bivariate and multivariate analysis. In the bivariate analysis, body mass index (r = 0.24), the sum of eight skinfolds (r = 0.55), percent body fat (r = 0.57), weekly running hours (r = -0.29), weekly running kilometres (r = -0.49), running speed during training (r = -0.50), and personal best time in a marathon (r = 0.72) were associated with race time. Results of the multiple regression analysis revealed an independent and negative association of weekly running kilometres and average speed in training with race time, as well as a significant positive association between the sum of eight skinfold thicknesses and race time. There was a significant positive association between 100-km race time and personal best time in a marathon. We conclude that both training and anthropometry were independently associated with race performance. These characteristics remained relevant even when controlling for personal best time in a marathon.

Ecologically Valid Carbohydrate Intake during Soccer-Specific Exercise Does Not Affect Running Performance in a Fed State

PubMed Central

Funnell, Mark P.; Dykes, Nick R.; Owen, Elliot J.; Mears, Stephen A.; Rollo, Ian; James, Lewis J.

2017-01-01

This study assessed the effect of carbohydrate intake on self-selected soccer-specific running performance. Sixteen male soccer players (age 23 ± 4 years; body mass 76.9 ± 7.2 kg; predicted VO2max = 54.2 ± 2.9 mL∙kg−1∙min−1; soccer experience 13 ± 4 years) completed a progressive multistage fitness test, familiarisation trial and two experimental trials, involving a modified version of the Loughborough Intermittent Shuttle Test (LIST) to simulate a soccer match in a fed state. Subjects completed six 15 min blocks (two halves of 45 min) of intermittent shuttle running, with a 15-min half-time. Blocks 3 and 6, allowed self-selection of running speeds and sprint times, were assessed throughout. Subjects consumed 250 mL of either a 12% carbohydrate solution (CHO) or a non-caloric taste matched placebo (PLA) before and at half-time of the LIST. Sprint times were not different between trials (CHO 2.71 ± 0.15 s, PLA 2.70 ± 0.14 s; p = 0.202). Total distance covered in self-selected blocks (block 3: CHO 2.07 ± 0.06 km; PLA 2.09 ± 0.08 km; block 6: CHO 2.04 ± 0.09 km; PLA 2.06 ± 0.08 km; p = 0.122) was not different between trials. There was no difference between trials for distance covered (p ≥ 0.297) or mean speed (p ≥ 0.172) for jogging or cruising. Blood glucose concentration was greater (p < 0.001) at the end of half-time during the CHO trial. In conclusion, consumption of 250 mL of 12% CHO solution before and at half-time of a simulated soccer match does not affect self-selected running or sprint performance in a fed state. PMID:28067762

Ecologically Valid Carbohydrate Intake during Soccer-Specific Exercise Does Not Affect Running Performance in a Fed State.

PubMed

Funnell, Mark P; Dykes, Nick R; Owen, Elliot J; Mears, Stephen A; Rollo, Ian; James, Lewis J

2017-01-05

This study assessed the effect of carbohydrate intake on self-selected soccer-specific running performance. Sixteen male soccer players (age 23 ± 4 years; body mass 76.9 ± 7.2 kg; predicted VO 2max = 54.2 ± 2.9 mL∙kg -1 ∙min -1 ; soccer experience 13 ± 4 years) completed a progressive multistage fitness test, familiarisation trial and two experimental trials, involving a modified version of the Loughborough Intermittent Shuttle Test (LIST) to simulate a soccer match in a fed state. Subjects completed six 15 min blocks (two halves of 45 min) of intermittent shuttle running, with a 15-min half-time. Blocks 3 and 6, allowed self-selection of running speeds and sprint times, were assessed throughout. Subjects consumed 250 mL of either a 12% carbohydrate solution (CHO) or a non-caloric taste matched placebo (PLA) before and at half-time of the LIST. Sprint times were not different between trials (CHO 2.71 ± 0.15 s, PLA 2.70 ± 0.14 s; p = 0.202). Total distance covered in self-selected blocks (block 3: CHO 2.07 ± 0.06 km; PLA 2.09 ± 0.08 km; block 6: CHO 2.04 ± 0.09 km; PLA 2.06 ± 0.08 km; p = 0.122) was not different between trials. There was no difference between trials for distance covered ( p ≥ 0.297) or mean speed ( p ≥ 0.172) for jogging or cruising. Blood glucose concentration was greater ( p < 0.001) at the end of half-time during the CHO trial. In conclusion, consumption of 250 mL of 12% CHO solution before and at half-time of a simulated soccer match does not affect self-selected running or sprint performance in a fed state.

Whole blood coagulation and platelet activation in the athlete: a comparison of marathon, triathlon and long distance cycling.

PubMed

Hanke, Alexander A; Staib, A; Görlinger, K; Perrey, M; Dirkmann, D; Kienbaum, P

2010-02-26

Serious thrombembolic events occur in otherwise healthy marathon athletes during competition. We tested the hypothesis that during heavy endurance sports coagulation and platelets are activated depending on the type of endurance sport with respect to its running fraction. 68 healthy athletes participating in marathon (MAR, running 42 km, n = 24), triathlon (TRI, swimming 2.5 km + cycling 90 km + running 21 km, n = 22), and long distance cycling (CYC, 151 km, n = 22) were included in the study. Blood samples were taken before and immediately after completion of competition to perform rotational thrombelastometry. We assessed coagulation time (CT), maximum clot firmness (MCF) after intrinsically activation and fibrin polymerization (FIBTEM). Furthermore, platelet aggregation was tested after activation with ADP and thrombin activating peptide 6 (TRAP) by using multiple platelet function analyzer. Complete data sets were obtained in 58 athletes (MAR: n = 20, TRI: n = 19, CYC: n = 19). CT significantly decreased in all groups (MAR -9.9%, TRI -8.3%, CYC -7.4%) without differences between groups. In parallel, MCF (MAR +7.4%, TRI +6.1%, CYC +8.3%) and fibrin polymerization (MAR +14.7%, TRI +6.1%, CYC +8.3%) were significantly increased in all groups. However, platelets were only activated during MAR and TRI as indicated by increased AUC during TRAP-activation (MAR +15.8%) and increased AUC during ADP-activation in MAR (+50.3%) and TRI (+57.5%). While coagulation is activated during physical activity irrespective of type we observed significant platelet activation only during marathon and to a lesser extent during triathlon. We speculate that prolonged running may increase platelet activity, possibly, due to mechanical alteration. Thus, particularly prolonged running may increase the risk of thrombembolic incidents in running athletes.

Whole blood coagulation and platelet activation in the athlete: A comparison of marathon, triathlon and long distance cycling

PubMed Central

2010-01-01

Introduction Serious thrombembolic events occur in otherwise healthy marathon athletes during competition. We tested the hypothesis that during heavy endurance sports coagulation and platelets are activated depending on the type of endurance sport with respect to its running fraction. Materials and Methods 68 healthy athletes participating in marathon (MAR, running 42 km, n = 24), triathlon (TRI, swimming 2.5 km + cycling 90 km + running 21 km, n = 22), and long distance cycling (CYC, 151 km, n = 22) were included in the study. Blood samples were taken before and immediately after completion of competition to perform rotational thrombelastometry. We assessed coagulation time (CT), maximum clot firmness (MCF) after intrinsically activation and fibrin polymerization (FIBTEM). Furthermore, platelet aggregation was tested after activation with ADP and thrombin activating peptide 6 (TRAP) by using multiple platelet function analyzer. Results Complete data sets were obtained in 58 athletes (MAR: n = 20, TRI: n = 19, CYC: n = 19). CT significantly decreased in all groups (MAR -9.9%, TRI -8.3%, CYC -7.4%) without differences between groups. In parallel, MCF (MAR +7.4%, TRI +6.1%, CYC +8.3%) and fibrin polymerization (MAR +14.7%, TRI +6.1%, CYC +8.3%) were significantly increased in all groups. However, platelets were only activated during MAR and TRI as indicated by increased AUC during TRAP-activation (MAR +15.8%) and increased AUC during ADP-activation in MAR (+50.3%) and TRI (+57.5%). Discussion While coagulation is activated during physical activity irrespective of type we observed significant platelet activation only during marathon and to a lesser extent during triathlon. We speculate that prolonged running may increase platelet activity, possibly, due to mechanical alteration. Thus, particularly prolonged running may increase the risk of thrombembolic incidents in running athletes. PMID:20452885

Performance and sex differences in 'Isklar Norseman Xtreme Triathlon'.

PubMed

Knechtle, Beat; Nikolaidis, Pantelis Theodoros; Stiefel, Michael; Rosemann, Thomas; Rüst, Christoph Alexander

2016-10-31

The performance and sex differences of long-distance triathletes competing in 'Ironman Hawaii' are well investigated. However, less information is available with regards to triathlon races of the Ironman distance held under extreme environmental conditions (e.g. extreme cold) such as the 'Isklar Norseman Xtreme Triathlon' which started in 2003. In 'Isklar Norseman Xtreme Triathlon', athletes swim at a water temperature of ~13-15°C, cycle at temperatures of ~5-20°C and run at temperatures of ~12-28°C in the valley and of ~2-12°C at Mt. Gaustatoppen. This study analysed the performance trends and sex differences in 'Isklar Norseman Xtreme Triathlon' held from 2003 to 2015 using mixed-effects regression analyses. During this period, a total of 175 women (10.6%) and 1,852 men (89.4%) successfully finished the race. The number of female (r² = 0.53, P = 0.0049) and male (r² = 0.37, P = 0.0271) finishers increased and the men-to-women ratio decreased (r² = 0.86, P < 0.0001). Men were faster than women in cycling (25.41 ± 2.84 km/h versus 24.25 ± 2.17 km/h) (P < 0.001), but not in swimming (3.06 ± 0.62 km/h vs. 2.94 ± 0.57 km/h), running (7.43 ± 1.13 km/h vs. 7.31 ± 0.93 km/h) and overall race time (874.57 ± 100.62 min vs. 899.95 ± 90.90 min) (P > 0.05). Across years, women improved in swimming and both women and men improved in cycling and in overall race time (P < 0.001). In running, however, neither women nor men improved (P > 0.05). In summary, in 'Isklar Norseman Xtreme Triathlon' from 2003 to 2015, the number of successful women increased across years, women achieved a similar performance to men in swimming, cycling and overall race time, and women improved across years in swimming, cycling and overall race time.

Effects of age and spa treatment on match running performance over two consecutive games in highly trained young soccer players.

PubMed

Buchheit, Martin; Horobeanu, Cosmin; Mendez-Villanueva, Alberto; Simpson, Ben M; Bourdon, Pitre C

2011-03-01

The aim of this study was to examine the effect of age and spa treatment (i.e. combined sauna, cold water immersion, and jacuzzi) on match running performance over two consecutive matches in highly trained young soccer players. Fifteen pre- (age 12.8 ± 0.6 years) and 13 post- (15.9 ± 1 y) peak height velocity (PHV) players played two matches (Matches 1 and 2) within 48 h against the same opposition, with no specific between-match recovery intervention (control). Five post-PHV players also completed another set of two consecutive matches, with spa treatment implemented after the first match. Match running performance was assessed using a global positioning system with very-high-intensity running (> 16.1-19.0 km · h(-1)), sprinting distance (>19 km · h(-1)), and peak match speed determined. Match 2 very-high-intensity running was "possibly" impaired in post-PHV players (-9 ± 33%; ± 90% confidence limits), whereas it was "very likely" improved for the pre-PHV players (+27 ± 22%). The spa treatment had a beneficial impact on Match 2 running performance, with a "likely" rating for sprinting distance (+30 ± 67%) and "almost certain" for peak match speed (+6.4 ± 3%). The results suggest that spa treatment is an effective recovery intervention for post-PHV players, while its value in pre-PHV players is questionable.

Body Mass and Circumference of Upper Arm Are Associated with Race Performance in Ultraendurance Runners in a Multistage Race--The Isarrun 2006

ERIC Educational Resources Information Center

Knechtle, Beat; Duff, Brida; Welzel, Ulrich; Kohler, Gotz

2009-01-01

In the present study, we investigated the association of anthropometric parameters with race performance in ultraendurance runners in a multistage ultraendurance run, in which athletes had to run 338 km within 5 consecutive days. In 17 male successful finishers, calculations of body mass, body height, skinfold thicknesses, extremity circumference,…

The Effect of Compression Stockings on Physiological and Psychological Responses after 5-km Performance in Recreationally Active Females.

PubMed

Treseler, Christine; Bixby, Walter R; Nepocatych, Svetlana

2016-07-01

Treseler, C, Bixby, WR, and Nepocatych, S. The effect of compression stockings on physiological and psychological responses after 5-Km performance in recreationally active females. J Strength Cond Res 30(7): 1985-1991, 2016-The purpose of the study was to examine the physiological and perceptual responses to wearing below-the-knee compression stockings (CS) after a 5-km running performance in recreationally active women. Nineteen women were recruited to participate in the study (20 ± 1 year, 61.4 ± 5.3 kg, 22.6 ± 3.9% body fat). Each participant completed two 5-km performance time trials with CS or regular socks in a counterbalanced order separated by 1 week. For each session, 5-km time, heart rate (HR), rate of perceived exertion (RPE), pain pressure threshold, muscle soreness (MS), and rate of perceived recovery were measured. There was no significant difference in average 5-km times between CS and regular socks (p = 0.74) and HR response (p = 0.42). However, significantly higher RPE and lower gain scores (%) for lower extremity MS but not for calf were observed with CS when compared with regular socks (p = 0.05, p = 0.01, and p = 0.3, respectively). Based on the results of this study, there were no significant improvements in average 5-km running time, heart rate, or perceived calf MS. However, participants perceived less MS in lower extremities and working harder with CS compared with regular socks. Compression stockings may not cause significant physiological improvements; however, there might be psychological benefits positively affecting postexercise recovery.

Influence of the world's most challenging mountain ultra-marathon on energy cost and running mechanics.

PubMed

Vernillo, Gianluca; Savoldelli, Aldo; Zignoli, Andrea; Trabucchi, Pietro; Pellegrini, Barbara; Millet, Grégoire P; Schena, Federico

2014-05-01

To examine the effects of the world's most challenging mountain ultra-marathon (Tor des Géants(®) 2012) on the energy cost of three types of locomotion (cycling, level and uphill running) and running kinematics. Before (pre-) and immediately after (post-) the competition, a group of ten male experienced ultra-marathon runners performed in random order three submaximal 4-min exercise trials: cycling at a power of 1.5 W kg(-1) body mass; level running at 9 km h(-1) and uphill running at 6 km h(-1) at an inclination of +15 % on a motorized treadmill. Two video cameras recorded running mechanics at different sampling rates. Between pre- and post-, the uphill-running energy cost decreased by 13.8 % (P = 0.004); no change was noted in the energy cost of level running or cycling (NS). There was an increase in contact time (+10.3 %, P = 0.019) and duty factor (+8.1 %, P = 0.001) and a decrease in swing time (-6.4 %, P = 0.008) in the uphill-running condition. After this extreme mountain ultra-marathon, the subjects modified only their uphill-running patterns for a more economical step mechanics.

Pre-exercise carbohydrate and fluid ingestion: influence of glycemic response on 10-km treadmill running performance in the heat.

PubMed

Mitchell, J B; Braun, W A; Pizza, F X; Forrest, M

2000-03-01

The purpose of this study was to determine the influence of ingesting solutions containing mixtures of carbohydrate (CHO) types on pre-exercise glycemic response, exercise-induced hypoglycemia, metabolic responses, and 10-km treadmill running performance in a warm environment. Ten trained runners completed 6, self-paced 10-km treadmill runs one hour after ingesting 900 ml of one of the following test solutions: a water placebo (WP), an 8 g 100 ml-1 high fructose corn syrup solution (HFG; 72 g CHO), a 6 g 100 ml-1 glucose solution (GLU; 54 g CHO), a 6 g.100 ml-1 sucrose/glucose mixture (SUG; 54 g CHO), or banana with water to equal 900 ml (BAN; approx. 54 g CHO). The sixth condition was 675 ml of an 8 g.100 ml-1 HFCS solution (LFG; 54 g CHO). Blood samples were taken prior to ingestion and every 15 min during rest and at 15 and 30 min, and at the end of the 10-km run. Blood was analyzed for glucose (BG) insulin (IN), glycerol, lactate, and percent change in plasma volume. Urine volume during the 1 hour of rest and change in body mass during exercise were also determined. A significant (p < 0.05) correlation (r = -0.684) was seen between the pre-exercise glycemic response (PEGR = area under the resting BG curve) and the change in BG from pre-EX to 15 min of exercise. BG at 15 min of exercise was significantly higher in the WP (5.22 mM) versus the other conditions (HFG = 3.32, LFG = 3.91, GLU = 3.38, BAN = 3.74 & SUG = 3.63 mM). Pre-exercise IN was lower in the WP (6.54 U ml-1) condition versus the other conditions (HFG = 22.1, LFG = 16.2, GLU = 23.3, BAN = 18.8 & SUG = 12.8 U.ml-1). Ten km performance times were not different (WP = 41.87, HFG = 41.66, LFG = 41.79, GLU = 41.65, BAN = 41.53, and SUG = 41.75 min). A significantly greater body mass loss occurred due to urine production during the 60 min of rest in the WP compared to the other conditions. The degree of exercise-induced decline in blood glucose was related to the PEGR; however, the decline in BG did not affect 10-km running performance. In addition, there were no differences in the metabolic responses during exercise between the different CHO types, nor did the type of CHO influence running performance. Finally, the presence of CHO and/or electrolytes in the hydration solutions produced a better fluid retention during the 60-min pre-exercise rest period compared to water. The results confirmed that if a competitive athlete consumed a breakfast prior to ingesting a CHO-electrolyte beverage, a practice that is common, the glycemic responses may be different.

Similarities and differences in anthropometry and training between recreational male 100-km ultra-marathoners and marathoners.

PubMed

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas

2012-01-01

Several recent investigations showed that the best marathon time of an individual athlete is also a strong predictor variable for the race time in a 100-km ultra-marathon. We investigated similarities and differences in anthropometry and training characteristics between 166 100-km ultra-marathoners and 126 marathoners in recreational male athletes. The association of anthropometric variables and training characteristics with race time was assessed by using bi- and multi-variate analysis. Regarding anthropometry, the marathoners had a significantly lower calf circumference (P < 0.05) and a significantly thicker skinfold at pectoral (P < 0.01), axilla (P < 0.05), and suprailiacal sites (P < 0.05) compared to the ultra-marathoners. Considering training characteristics, the marathoners completed significantly fewer hours (P < 0.001) and significantly fewer kilometres (P < 0.001) during the week, but they were running significantly faster during training (P < 0.001). The multi-variate analysis showed that age (P < 0.0001), body mass (P = 0.011), and percent body fat (P = 0.019) were positively and weekly running kilometres (P < 0.0001) were negatively related to 100-km race times in the ultra-marathoners. In the marathoners, percent body fat (P = 0.002) was positively and speed in running training (P < 0.0001) was negatively associated with marathon race times. In conclusion, these data suggest that performance in both marathoners and 100-km ultra-marathoners is inversely related to body fat. Moreover, marathoners rely more on speed in running during training whereas ultra-marathoners rely on volume in running training.

Similarities and Differences in Pacing Patterns in a 161-km and 101-km Ultra-Distance Road Race.

PubMed

Tan, Philip L S; Tan, Frankie H Y; Bosch, Andrew N

2016-08-01

Tan, PLS, Tan, FHY, and Bosch, AN. Similarities and differences in pacing patterns in a 161-km and 101-km ultra-distance road race. J Strength Cond Res 30(8): 2145-2155, 2016-The purpose of this study was to establish and compare the pacing patterns of fast and slow finishers in a tropical ultra-marathon. Data were collected from the Craze Ultra-marathon held on the 22nd and 21st of September in 2012 and 2013, respectively. Finishers of the 161-km (N = 47) and 101-km (N = 120) categories of the race were divided into thirds (groups A-C) by merit of finishing time. Altogether, 17 and 11 split times were recorded for the 161-km and 101-km finishers, respectively, and used to calculate the mean running speed for each distance segment. Running speed for the first segment was normalized to 100, with all subsequent splits adjusted accordingly. Running speed during the last 5 km was calculated against the mean race pace to establish the existence of an end spurt. A reverse J-shaped pacing profile was demonstrated in all groups for both distance categories and only 38% of the finishers executed an end spurt. In the 101-km category, in comparison with groups B and C, group A maintained a significantly more even pace (p = 0.013 and 0.001, respectively) and completed the race at a significantly higher percent of initial starting speed (p = 0.001 and 0.001, respectively). Descriptive data also revealed that the top 5 finishers displayed a "herd-behavior" by staying close to the lead runner in the initial portion of the race. These findings demonstrate that to achieve a more even pace, recreational ultra-runners should adopt a patient sustainable starting speed, with less competitive runners setting realistic performance goals whereas competitive runners with a specific time goal to consider running in packs of similar pace.

Age and gender interactions in short distance triathlon performance.

PubMed

Etter, Franziska; Knechtle, Beat; Bukowski, Arkadiusz; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2013-01-01

This study investigated the participation and performance trends as well as the age and gender interaction at the Olympic distance 'Zürich Triathlon' (1.5 km swim, 40 km cycle and 10 km run) from 2000 to 2010 in 7,939 total finishers (1,666 females and 6,273 males). Female triathletes aged from 40 to 54 years significantly (P < 0.05) increased their participation while the participation of younger females and males remained stable. Males of 50-54 years of age and females of 45-49 years of age improved their total race time. For elite top five overall triathletes, mean gender differences in swimming, cycling, running and overall race time were 15.2 ± 4.6%, 13.4 ± 2.3%, 17.1 ± 2.5%, and 14.8 ± 1.8%, respectively. For both elite and age group athletes, the gender difference in cycling time was significantly (P <0.001) lower than for swimming and running. The gender difference in overall Olympic distance triathlon performance increased after the age of 35 years, which appeared earlier compared to long distance triathlon as suggested by previous studies. Future investigations should compare gender difference in performance for different endurance events across age to confirm a possible effect of exercise duration on gender difference with advancing age.

High-intensity cycle interval training improves cycling and running performance in triathletes.

PubMed

Etxebarria, Naroa; Anson, Judith M; Pyne, David B; Ferguson, Richard A

2014-01-01

Effective cycle training for triathlon is a challenge for coaches. We compared the effects of two variants of cycle high-intensity interval training (HIT) on triathlon-specific cycling and running. Fourteen moderately-trained male triathletes ([Formula: see text]O2peak 58.7 ± 8.1 mL kg(-1) min(-1); mean ± SD) completed on separate occasions a maximal incremental test ([Formula: see text]O2peak and maximal aerobic power), 16 × 20 s cycle sprints and a 1-h triathlon-specific cycle followed immediately by a 5 km run time trial. Participants were then pair-matched and assigned randomly to either a long high-intensity interval training (LONG) (6-8 × 5 min efforts) or short high-intensity interval training (SHORT) (9-11 × 10, 20 and 40 s efforts) HIT cycle training intervention. Six training sessions were completed over 3 weeks before participants repeated the baseline testing. Both groups had an ∼7% increase in [Formula: see text]O2peak (SHORT 7.3%, ±4.6%; mean, ±90% confidence limits; LONG 7.5%, ±1.7%). There was a moderate improvement in mean power for both the SHORT (10.3%, ±4.4%) and LONG (10.7%, ±6.8%) groups during the last eight 20-s sprints. There was a small to moderate decrease in heart rate, blood lactate and perceived exertion in both groups during the 1-h triathlon-specific cycling but only the LONG group had a substantial decrease in the subsequent 5-km run time (64, ±59 s). Moderately-trained triathletes should use both short and long high-intensity intervals to improve cycling physiology and performance. Longer 5-min intervals on the bike are more likely to benefit 5 km running performance.

Is There an Optimal Speed for Economical Running?

PubMed

Black, Matthew I; Handsaker, Joseph C; Allen, Sam J; Forrester, Stephanie E; Folland, Jonathan P

2018-01-01

The influence of running speed and sex on running economy is unclear and may have been confounded by measurements of oxygen cost that do not account for known differences in substrate metabolism, across a limited range of speeds, and differences in performance standard. Therefore, this study assessed the energy cost of running over a wide range of speeds in high-level and recreational runners to investigate the effect of speed (in absolute and relative terms) and sex (men vs women of equivalent performance standard) on running economy. To determine the energy cost (kcal · kg -1  · km -1 ) of submaximal running, speed at lactate turn point (sLTP), and maximal rate of oxygen uptake, 92 healthy runners (high-level men, n = 14; high-level women, n = 10; recreational men, n = 35; recreational women, n = 33) completed a discontinuous incremental treadmill test. There were no sex-specific differences in the energy cost of running for the recreational or high-level runners when compared at absolute or relative running speeds (P > .05). The absolute and relative speed-energy cost relationships for the high-level runners demonstrated a curvilinear U shape with a nadir reflecting the most economical speed at 13 km/h or 70% sLTP. The high-level runners were more economical than the recreational runners at all absolute and relative running speeds (P < .05). These findings demonstrate that there is an optimal speed for economical running, there is no sex-specific difference, and high-level endurance runners exhibit better running economy than recreational endurance runners.

Running Performance of a Pinning-Type Superconducting Magnetic Levitation Guide

NASA Astrophysics Data System (ADS)

Okano, M.; Iwamoto, T.; Furuse, M.; Fuchino, S.; Ishii, I.

2006-06-01

A pinning-type superconducting magnetic levitation guide with bulk high-Tc superconductors was studied for use as a goods transportation system, an energy storage system, etc. A superconducting magnetic levitation running test apparatus with a circular track of ca. 38 m length, 12 m diameter, which comprises the magnetic rail constituted by Nd-B-Fe rare-earth permanent magnets and steel plates, was manufactured to examine loss and high-speed performance of the magnetic levitation guide. Running tests were conducted in air. These tests clarify that a vehicle supported by a superconducting magnetic levitation guide runs stably at speeds greater than 42 km/h above the circular track.

Older females are at higher risk for medical complications during 21 km road race running: a prospective study in 39 511 race starters--SAFER study III.

PubMed

Schwabe, Karen; Schwellnus, Martin P; Derman, Wayne; Swanevelder, Sonja; Jordaan, Esme

2014-06-01

The half-marathon (21 km) race is a very popular mass community-based distance running event. It is important to determine risk factors for medical complications during these events, so that prevention programmes can be developed. To determine risk factors associated with medical complications during 21 km road running events. Prospective study. Two Oceans half-marathon (21 km) races. 39 511 starters in the 21 km race. Medical complications (defined as any runner requiring assessment by a doctor at the race medical facility or a local hospital on race day) were recorded over a 4-year study period. Medical complications were subdivided according to the system affected and by final diagnosis. A Poisson regression model was used to determine risk factors for any medical complication and more common specific complications. Independent risk factors for medical complication during 21 km running were older female runners (women >50 vs  ≤50 years; p<0.0001) and year of observation (2008 vs 2011; p=0.0201: 2009 vs 2011: p=0.0019; 2010 vs 2011: p=0.0096). Independent risk factors for specific common medical complications were: postural hypotension (women, slow running pace), musculoskeletal complications (less running experience, slower running pace) and dermatological complications (women). Older female runners are at higher risk of developing medical complications during 21 km road running races. Environmental conditions in a particularly cold climate may also play a role. Less running experience and slower running pace are associated with specific medical complications. Medical staff can now plan appropriate care on race days, and interventions can be developed to reduce the risk of medical complications in 21 km races.

Are gait characteristics and ground reaction forces related to energy cost of running in elite Kenyan runners?

PubMed

Santos-Concejero, J; Tam, N; Coetzee, D R; Oliván, J; Noakes, T D; Tucker, R

2017-03-01

The aim of this study was to determine whether gait cycle characteristics are associated with running economy in elite Kenyan runners. Fifteen elite Kenyan male runners completed two constant-speed running sets on a treadmill (12 km ·h -1 and 20 km ·h -1 ). VO 2 and respiratory exchange ratio values were measured to calculate steady-state oxygen and energy cost of running. Gait cycle characteristics and ground contact forces were measured at each speed. Oxygen cost of running at different velocities was 192.2 ± 14.7 ml· kg -1 · km -1 at 12 km· h -1 and 184.8 ± 9.9 ml· kg -1 · km -1 at 20 km· h -1 , which corresponded to a caloric cost of running of 0.94 ± 0.07 kcal ·kg -1 ·km -1 and 0.93 ± 0.07 kcal· kg -1 · km -1 . We found no significant correlations between oxygen and energy cost of running and biomechanical variables and ground reaction forces at either 12 or 20 km· h -1 . However, ground contact times were ~10.0% shorter (very large effect) than in previously published literature in elite runners at similar speeds, alongside an 8.9% lower oxygen cost (very large effect). These results provide evidence to hypothesise that the short ground contact times may contribute to the exceptional running economy of Kenyan runners.

Is There Evidence that Runners can Benefit from Wearing Compression Clothing?

PubMed

Engel, Florian Azad; Holmberg, Hans-Christer; Sperlich, Billy

2016-12-01

Runners at various levels of performance and specializing in different events (from 800 m to marathons) wear compression socks, sleeves, shorts, and/or tights in attempt to improve their performance and facilitate recovery. Recently, a number of publications reporting contradictory results with regard to the influence of compression garments in this context have appeared. To assess original research on the effects of compression clothing (socks, calf sleeves, shorts, and tights) on running performance and recovery. A computerized research of the electronic databases PubMed, MEDLINE, SPORTDiscus, and Web of Science was performed in September of 2015, and the relevant articles published in peer-reviewed journals were thus identified rated using the Physiotherapy Evidence Database (PEDro) Scale. Studies examining effects on physiological, psychological, and/or biomechanical parameters during or after running were included, and means and measures of variability for the outcome employed to calculate Hedges'g effect size and associated 95 % confidence intervals for comparison of experimental (compression) and control (non-compression) trials. Compression garments exerted no statistically significant mean effects on running performance (times for a (half) marathon, 15-km trail running, 5- and 10-km runs, and 400-m sprint), maximal and submaximal oxygen uptake, blood lactate concentrations, blood gas kinetics, cardiac parameters (including heart rate, cardiac output, cardiac index, and stroke volume), body and perceived temperature, or the performance of strength-related tasks after running. Small positive effect sizes were calculated for the time to exhaustion (in incremental or step tests), running economy (including biomechanical variables), clearance of blood lactate, perceived exertion, maximal voluntary isometric contraction and peak leg muscle power immediately after running, and markers of muscle damage and inflammation. The body core temperature was moderately affected by compression, while the effect size values for post-exercise leg soreness and the delay in onset of muscle fatigue indicated large positive effects. Our present findings suggest that by wearing compression clothing, runners may improve variables related to endurance performance (i.e., time to exhaustion) slightly, due to improvements in running economy, biomechanical variables, perception, and muscle temperature. They should also benefit from reduced muscle pain, damage, and inflammation.

Side-suspended High-Tc Superconducting Maglev Prototype Vehicle Running at a High Speed in an Evacuated Circular Test Track

NASA Astrophysics Data System (ADS)

Zhou, Dajin; Zhao, Lifeng; Cui, Chenyu; Zhang, Yong; Guo, Jianqiang; Zhao, Yong

2017-07-01

High-T c superconductor (HTS) and permanent magnetic guideway (PMG) based maglev train is intensively studied in China, Japan, Germany and Brazil, mainly through static or vibration test. Amongst these studies, only a few of reports are available for the direct and effective assessment on the dynamic performance of the HTS maglev vehicle by running on a straight or circular PMG track. The highest running speed of these experiments is lower than 50 km/h. In this paper, a side-suspended HTS permanent magnetic guideway maglev system was proposed and constructed in order to increase the running speed in a circular track. By optimizing the arrangement of YBCO bulks besides the PMG, the side-suspended HTS maglev prototype vehicle was successfully running stably at a speed as high as 150 km/h in a circular test track with 6.5 m in diameter, and in an evacuated tube environment, in which the pressure is 5 × 103 Pa.

The valid measurement of running economy in runners.

PubMed

Shaw, Andrew J; Ingham, Stephen A; Folland, Jonathan P

2014-10-01

Oxygen cost (OC) is commonly used to assess an athlete's running economy, although the validity of this measure is often overlooked. This study evaluated the validity of OC as a measure of running economy by comparison with the underlying energy cost (EC). In addition, the most appropriate method of removing the influence of body mass was determined to elucidate a measure of running economy that enables valid interindividual comparisons. One hundred and seventy-two highly trained endurance runners (males, n = 101; females, n = 71) performed a discontinuous submaximal running assessment, consisting of approximately seven 3-min stages (1 km·h increments), to determine the absolute OC (L·km) and EC (kcal·km) for the four speeds below lactate turn point. Comparisons between models revealed linear ratio scaling to be a more suitable method than power function scaling for removing the influence of body mass for both EC (males, R = 0.589 vs 0.588; females, R = 0.498 vs 0.482) and OC (males, R = 0.657 vs 0.652; females, R = 0.532 vs 0.531). There were stepwise increases in EC and RER with increments in running speed (both, P < 0.001). However, no differences were observed for OC across the four monitored speeds (P = 0.54). Although EC increased with running speed, OC was insensitive to changes in running speed and, therefore, does not appear to provide a valid index of the underlying EC of running, likely due to the inability of OC to account for variations in substrate use. Therefore, EC should be used as the primary measure of running economy, and for runners, an appropriate scaling with body mass is recommended.

Specific Intensity for Peaking: Is Race Pace the Best Option?

PubMed Central

Munoz, Iker; Seiler, Stephen; Alcocer, Alberto; Carr, Natasha; Esteve-Lanao, Jonathan

2015-01-01

Background: The peaking period for endurance competition is characterized for a relative increase of the intensity of training, after a longer period of training relatively dominated by lower intensity and higher volume Objectives: The present study was designed to compare physiological and 10 km performance effects of high intensity training (HIT) versus race pace interval training (RP) during peaking for competition in well-trained runners. Patients and Methods: 13 athletes took part in the study, they were divided into two groups: HIT and RP. HIT performed short intervals at ~105% of the maximal aerobic velocity (MAV), while RP trained longer intervals at a speed of ~90% of the MAV (a speed approximating 10 km race pace). After 12 weeks of baseline training, the athletes trained for 6 weeks under one of the two peaking regimes. Subjects performed 10 km prior to and after the intervention period. The total load of training was matched between groups during the treatment phase. Subjects completed a graded treadmill running test until volitional exhaustion prior to each 10 km race. MAV was determined as the minimal velocity eliciting maximal oxygen consumption (VO2max). Results: Both groups significantly improved their 10 km time (35 minutes 29 seconds ± 1 minutes 41 seconds vs 34 minutes 53 seconds ± 1 minutes 55 seconds, P < 0.01 for HIT; 35 minutes 27 seconds ± 1 minutes 40 seconds vs 34 minutes 53 seconds ± 1 minutes 18 seconds P < 0.01 for RP). VO2max increased after HIT (69 ± 3.6 vs 71.5 ± 4.2 ml.Kg-1.min-1, P < 0.05); while it didn’t for RP (68.4 ± 6 vs 69.8 ± 3 ml.Kg-1.min-1, p>0.05). In contrast, running economy decreased significantly after HIT (210 ± 6 ml.Kg-1.km-1 vs 218 ± 9, P < 0.05). Conclusions: A 6 week period of training at either 105% of MAV or 90% of MAV yielded similar performance gains in a 10km race performed at ~90% MAV. Therefore, the physiological impact of HIT training seems to be positive for VO2max but negative for running economy. PMID:26448854

Relative Match Intensities at High Altitude in Highly-Trained Young Soccer Players (ISA3600).

PubMed

Buchheit, Martin; Hammond, Kristal; Bourdon, Pitre C; Simpson, Ben M; Garvican-Lewis, Laura A; Schmidt, Walter F; Gore, Christopher J; Aughey, Robert J

2015-03-01

To compare relative match intensities of sea-level versus high-altitude native soccer players during a 2-week camp at 3600 m, data from 7 sea-level (Australian U17 National team, AUS) and 6 high-altitude (a Bolivian U18 team, BOL) native soccer players were analysed. Two matches were played at sea-level and three at 3600 m on Days 1, 6 and 13. The Yo-Yo Intermittent recovery test (vYo-YoIR1) was performed at sea-level, and on Days 3 and 10. Match activity profiles were measured via 10-Hz GPS. Distance covered >14.4 km.h(-1) (D>14.4 km·h(-1)) and >80% of vYo-YoIR1 (D>80%vYo-YoIR1) were examined. Upon arrival at altitude, there was a greater decrement in vYo-YoIR1 (Cohen's d +1.0, 90%CL ± 0.8) and D>14.4 km·h(-1) (+0.5 ± 0.8) in AUS. D>14.4 km.h(-1) was similarly reduced relative to vYo-YoIR1 in both groups, so that D>80%vYo-YoIR1 remained similarly unchanged (-0.1 ± 0.8). Throughout the altitude sojourn, vYo-YoIR1 and D>14.4 km·h(-1) increased in parallel in AUS, so that D>80%vYo-YoIR1 remained stable in AUS (+6.0%/match, 90%CL ± 6.7); conversely D>80%vYo-YoIR1 decreased largely in BOL (-12.2%/match ± 6.2). In sea-level natives competing at high-altitude, changes in match running performance likely follow those in high-intensity running performance. Bolivian data confirm that increases in 'fitness' do not necessarily translate into greater match running performance, but rather in reduced relative exercise intensity. Key pointsWhen playing at high-altitude, players may alter their activities during matches in relation to their transient maximal physical capacities, possibly to maintain a 'tolerable' relative exercise intensity.While there is no doubt that running performance per se in not the main determinant of match outcomes (Carling, 2013), fitness levels influence relative match intensity (Buchheit et al., 2012, Mendez-Villanueva et al., 2013), which in-turn may impact on decision making and skill performance (Rampinini et al., 2008).In the context of high-altitude competitions, it is therefore recommended to arrive early enough (i.e., ~2 weeks) to allow (at least partial) acclimatisation, and in turn, allow sea-level native players to regulate their running activities in relation to both actual game demands and relative match intensity.

The Effects of a Sport-Specific Maximal Strength and Conditioning Training on Critical Velocity, Anaerobic Running Distance, and 5-km Race Performance.

PubMed

Karsten, Bettina; Stevens, Liesbeth; Colpus, Mark; Larumbe-Zabala, Eneko; Naclerio, Fernando

2016-01-01

To investigate the effects of a sport-specific maximal 6-wk strength and conditioning program on critical velocity (CV), anaerobic running distance (ARD), and 5-km time-trial performance (TT). 16 moderately trained recreational endurance runners were tested for CV, ARD, and TT performances on 3 separate occasions (baseline, midstudy, and poststudy). Participants were randomly allocated into a strength and conditioning group (S&C; n = 8) and a comparison endurance-training-only group (EO; n = 8). During the first phase of the study (6 wk), the S&C group performed concurrent maximal strength and endurance training, while the EO group performed endurance-only training. After the retest of all variables (midstudy), both groups subsequently, during phase 2, performed another 6 wk of endurance-only training that was followed by poststudy tests. No significant change for CV was identified in either group. The S&C group demonstrated a significant decrease for ARD values after phases 1 and 2 of the study. TT performances were significantly different in the S&C group after the intervention, with a performance improvement of 3.62%. This performance increase returned close to baseline after the 6-wk endurance-only training. Combining a 6-wk resistance-training program with endurance training significantly improves 5-km TT performance. Removing strength training results in some loss of those performance improvements.

Is EMG of the lower leg dependent on weekly running mileage?

PubMed

Baur, H; Hirschmüller, A; Müller, S; Cassel, M; Mayer, F

2012-01-01

Neuromuscular activity of the lower leg is dependent on the task performed, speed of movement and gender. Whether training volume influences neuromuscular activity is not known. The EMG of physically active persons differing in running mileage was analysed to investigate this. 55 volunteers were allocated to a low (LM: < 30 km), intermediate (IM: > 30 km & < 45 km) or high mileage (HM: > 45 km) group according to their weekly running volume. Neuromuscular activity of the lower leg was measured during running (3.33 m·s - 1). Mean amplitude values for preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle.Higher activity in the gastrocnemius group was observed in weight acceptance in LM compared to IM (+30%) and HM (+25%) but lower activity was present in the push-off for LM compared to IM and HM. For the peroneal muscle, differences were present in the push-off where HM showed increased activity compared to IM (+24%) and LM (+60%). The tibial muscle revealed slightly lower activity during preactivation for the high mileage runners. Neuromuscular activity differs during stance between the high and intermediate group compared to low mileage runners. Slight adaptations in neuromuscular activation indicate a more target-oriented activation strategy possibly due to repetitive training in runners with higher weekly mileage. © Georg Thieme Verlag KG Stuttgart · New York.

Comparison of Two Fluid Replacement Protocols During a 20-km Trail Running Race in the Heat.

PubMed

Lopez, Rebecca M; Casa, Douglas J; Jensen, Katherine A; Stearns, Rebecca L; DeMartini, Julie K; Pagnotta, Kelly D; Roti, Melissa W; Armstrong, Lawrence E; Maresh, Carl M

2016-09-01

Lopez, RM, Casa, DJ, Jensen, K, Stearns, RL, DeMartini, JK, Pagnotta, KD, Roti, MW, Armstrong, LE, and Maresh, CM. Comparison of two fluid replacement protocols during a 20-km trail running race in the heat. J Strength Cond Res 30(9): 2609-2616, 2016-Proper hydration is imperative for athletes striving for peak performance and safety, however, the effectiveness of various fluid replacement strategies in the field setting is unknown. The purpose of this study was to investigate how two hydration protocols affect physiological responses and performance during a 20-km trail running race. A randomized, counter-balanced, crossover design was used in a field setting (mean ± SD: WBGT 28.3 ± 1.9° C). Well-trained male (n = 8) and female (n = 5) runners (39 ± 14 years; 175 ± 9 cm; 67.5 ± 11.1 kg; 13.4 ± 4.6% BF) completed two 20-km trail races (5 × 4-km loop) with different water hydration protocols: (a) ad libitum (AL) consumption and (b) individualized rehydration (IR). Data were analyzed using repeated measures ANOVA. Paired t-tests compared pre-race-post-race measures. Main outcome variables were race time, heart rate (HR), gastrointestinal temperature (TGI), fluid consumed, percent body mass loss (BML), and urine osmolality (Uosm). Race times between groups were similar. There was a significant condition × time interaction (p = 0.048) for HR, but TGI was similar between conditions. Subjects replaced 30 ± 14% of their water losses in AL and 64 ± 16% of their losses in IR (p < 0.001). Ad libitum trial experienced greater BML (-2.6 ± 0.5%) compared with IR (-1.3 ± 0.5%; p < 0.001). Pre-race to post-race Uosm differences existed between AL (-273 ± 146 mOsm) and IR (-145 ± 215 mOsm, p = 0.032). In IR, runners drank twice as much fluid than AL during the 20-km race, leading to > 2% BML in AL. Ad libitum drinking resulted in 1.3% greater BML over the 20-km race, which resulted in no thermoregulatory or performance differences from IR.

Cross-sectional relationships of exercise and age to adiposity in60,617 male runners

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Paul T.; Pate, Russell R.

2004-06-01

The objective of this report is to assess in men whether exercise affects the estimated age-related increase in adiposity, and contrariwise, whether age affects the estimated exercise-related decrease in adiposity. Cross-sectional analyses of 64,911 male runners who provided data on their body mass index (97.6 percent), waist (91.1 percent), hip (47.1 percent), and chest circumferences (77.9 percent). Between 18 to 55 years old, the decline in BMI with weekly distance run (slope+-SE) was significantly greater in men 25-55 years old (slope+-:-0.036+-0.001 kg/m2 per km/wk) than in younger men (-0.020+-0.002 kg/m 2 per km/wk). Declines in waist circumference with running distancemore » were also significantly greater in older than younger men (P<10-9 for trend),i.e., the slopes decreased progressively from -0.035+-0.004 cm per km/wk in 18-25 year old men to -0.097+-0.003 cm per km/wk in 50-55 year old men. Increases in BMI with age were greater for men who ran under 16km/wk than for longer distance runners. Waist circumference increased with age at all running levels, but the increase appeared to diminish by running further (0.259+-0.015 cm per year if running<8 km/wk and 0.154+-0.003 cm per year for>16 km/wk). In men over 50 years old, BMI declined -0.038+-0.001 kg/m2 per km/wk run when adjusted for age and declined -0.054+-0.003 kg/m2 (increased 0.021+-0.007 cm) per year of age when adjusted for running distance. Their waist circumference declined-0.096+-0.002 cm per km/wk run when adjusted for age and increased 0.021+-0.007 cm per year of age when adjusted for running distance. These cross-sectional data suggest that age and vigorous exercise interact with each other in affecting mens adiposity, and support the proposition that vigorous physical activity must increase with age to prevent middle-age weight gain. We estimate that a man who ran 16 km/wk at age 25 would need to increase their weekly running distance by 65.7 km/wk by age 50 in order to maintain his same waist circumference.« less

Dose-response effect of photobiomodulation therapy on neuromuscular economy during submaximal running.

PubMed

Dellagrana, Rodolfo André; Rossato, Mateus; Sakugawa, Raphael Luiz; Lazzari, Caetano Decian; Baroni, Bruno Manfredini; Diefenthaeler, Fernando

2018-02-01

The purpose of this study was to verify the photobiomodulation therapy (PBMT) effects with different doses on neuromuscular economy during submaximal running tests. Eighteen male recreational runners participate in a randomized, double-blind, and placebo-controlled trial, which each participant was submitted to the same testing protocol in five conditions: control, placebo, and PBMT with doses of 15, 30, and 60 J per site (14 sites in each lower limb). The submaximal running was performed at 8 and 9 km h -1 during 5 min for each velocity. Muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), and gastrocnemius lateralis (GL) was collected during the last minute of each running test. The root mean square (RMS) was normalized by maximal isometric voluntary contraction (MIVC) performed a priori in an isokinetic dynamometer. The RMS sum of all muscles (RMS LEG ) was considered as main neuromuscular economy parameter. PBMT with doses of 15, 30, and 60 J per site [33 diodes = 5 lasers (850 nm), 12 LEDs (670 nm), 8 LEDs (880 nm), and 8 LEDs (950 nm)] or placebo applications occurred before running tests. For the statistical analysis, the effect size was calculated. Moreover, a qualitative inference was used to determine the magnitude of differences between groups. Peak torque and RMS during MIVCs showed small effect sizes. According to magnitude-based inference, PBMT with dose of 15 J per site showed possibly and likely beneficial effects on neuromuscular economy during running at 8 and 9 km h -1 , respectively. On other hand, PBMT with doses of 30 and 60 J per site showed possible beneficial effects only during running at 9 km h -1 . We concluded that PBMT improve neuromuscular economy and the best PBMT dose was 15 J per site (total dose of 420 J).

Half-marathoners are younger and slower than marathoners.

PubMed

Knechtle, Beat; Nikolaidis, Pantelis T; Zingg, Matthias A; Rosemann, Thomas; Rüst, Christoph A

2016-01-01

Age and performance trends of elite and recreational marathoners are well investigated, but not for half-marathoners. We analysed age and performance trends in 508,108 age group runners (125,894 female and 328,430 male half-marathoners and 10,205 female and 43,489 male marathoners) competing between 1999 and 2014 in all flat half-marathons and marathons held in Switzerland using single linear regression analyses, mixed-effects regression analyses and analyses of variance. The number of women and men increased across years in both half-marathons and marathons. There were 12.3 times more female half-marathoners than female marathoners and 7.5 times more male half-marathoners than male marathoners. For both half-marathons and marathons, most of the female and male finishers were recorded in age group 40-44 years. In half-marathons, women (10.29 ± 3.03 km/h) were running 0.07 ± 0.06 km/h faster (p < 0.001) than men (10.22 ± 3.06 km/h). Also in marathon, women (14.77 ± 4.13 km/h) were running 0.28 ± 0.16 km/h faster (p < 0.001) than men (14.48 ± 4.07 km/h). In marathon, women (42.18 ± 10.63 years) were at the same age than men (42.06 ± 10.45 years) (p > 0.05). Also in half-marathon, women (41.40 ± 10.63 years) were at the same age than men (41.31 ± 10.30 years) (p > 0.05). However, women and men marathon runners were older than their counterpart half-marathon runners (p < 0.001). In summary, (1) more athletes competed in half-marathons than in marathons, (2) women were running faster than men, (3) half-marathoners were running slower than marathoners, and (4) half-marathoners were younger than marathoners.

The effects of wearing undersized lower-body compression garments on endurance running performance.

PubMed

Dascombe, Ben J; Hoare, Trent K; Sear, Joshua A; Reaburn, Peter R; Scanlan, Aaron T

2011-06-01

To examine whether wearing various size lower-body compression garments improves physiological and performance parameters related to endurance running in well-trained athletes. Eleven well-trained middle-distance runners and triathletes (age: 28.4 ± 10.0 y; height: 177.3 ± 4.7 cm; body mass: 72.6 ± 8.0 kg; VO2max: 59.0 ± 6.7 mL·kg-1·min-1) completed repeat progressive maximal tests (PMT) and time-to-exhaustion (TTE) tests at 90% VO2max wearing either manufacturer-recommended LBCG (rLBCG), undersized LBCG (uLBCG), or loose running shorts (CONT). During all exercise testing, several systemic and peripheral physiological measures were taken. The results indicated similar effects of wearing rLBCG and uLBCG compared with the control. Across the PMT, wearing either LBCG resulted in significantly (P < .05) increased oxygen consumption, O2 pulse, and deoxyhemoglobin (HHb) and decreased running economy, oxyhemoglobin, and tissue oxygenation index (TOI) at low-intensity speeds (8-10 km·h-1). At higher speeds (12-18 km·h-1), wearing LBCG increased regional blood flow (nTHI) and HHb values, but significantly lowered heart rate and TOI. During the TTE, wearing either LBCG significantly (P < .05) increased HHb concentration, whereas wearing uLBCG also significantly (P < .05) increased nTHI. No improvement in endurance running performance was observed in either compression condition. The results suggest that wearing LBCG facilitated a small number of cardiorespiratory and peripheral physiological benefits that appeared mostly related to improvements in venous flow. However, these improvements appear trivial to athletes, as they did not correspond to any improvement in endurance running performance.

Changes in the acid-base balance and lactate concentration in the blood in amateur ultramarathon runners during a 100-km run

PubMed Central

Żychowska, M; Konieczna, A; Ratkowski, W; Radzimiński, Ł

2015-01-01

The aim of this study was to analyse the acid-base balance and partial pressure of blood gases of participants during a 100-km run. Fourteen experienced amateur ultramarathon runners (age: 43.36±11.83 years; height: 175.29±6.98 cm; weight: 72.12±7.36 kg) completed the 100-km run. Blood samples were taken before the run; after 25, 50, 75, and 100 km; and 12 and 24 hours after the run. There were significant differences (p<0.05) between the mean values registered for acid-alkaline balance, buffering alkalies, and current bicarbonate in each segment of the run, especially during the third, fourth, and fifth segments of the run (i.e., between 50 and 100 km), and there were only significant differences associated with buffering alkalies and current bicarbonate during the recovery. However, all the changes were within the physiological norm. A significant decrease in the compressibility of oxygen was observed after 100 km (from 92.80±15.67 to 88.36±13.71 mmHg) and continued during the recovery to 75.06±8.60 mmHg 12 h after the run. Also there was a decrease in saturation to a mean value of 93.78±3.10 at 12 h after the run. Generally the amateurs runners are able to adjust their running speed so as not to provoke a significant acid-base imbalance or lactate acid accumulation. PMID:26424931

Integrative Neuromuscular Training and Sex-Specific Fitness Performance in 7-Year-Old Children: An Exploratory Investigation

PubMed Central

Faigenbaum, Avery D.; Myer, Gregory D.; Farrell, Anne; Radler, Tracy; Fabiano, Marc; Kang, Jie; Ratamess, Nicholas; Khoury, Jane; Hewett, Timothy E

2014-01-01

Context: Integrative neuromuscular training (INT) has successfully enhanced physical fitness and reduced abnormal biomechanics, which appear to decrease injury rates in adolescent female athletes. If not addressed at the proper time, low levels of physical fitness and abnormal mechanics may predispose female athletes to an increased risk of musculoskeletal injuries. Objectives To evaluate sex-specific effects of INT on selected measures of health- and skill-related fitness in children during physical education (PE). Design: Cohort study. Setting: Public primary school. Patients or Other Participants: Forty children (16 boys, 24 girls; age = 7.6 ± 0.3 years, height = 124.5 ± 6.4 cm, mass = 29.5 ± 7.6 kg) from 2 second-grade PE classes. Intervention(s): The classes were randomized into the PE-plus-INT group (10 boys, 11 girls) or the control group (6 boys, 13 girls) that participated in traditional PE. The INT was performed 2 times per week during the first approximately 15 minutes of each PE class and consisted of body weight exercises. Main Outcome Measure(s): Push-up, curl-up, standing long jump, single-legged hop, single-legged balance, sit-and-reach flexibility test, shuttle run, and 0.8-km run. Results: At baseline, the boys demonstrated higher levels of performance in most of the fitness measurements as evidenced by greater performance on the push-up, standing long jump, single-legged hop, shuttle run, and 0.8-km run (P < .05). In the evaluation of the training effects, we found intervention effects in the girls for enhanced INT-induced gains in performance relative to the control group on the curl-up, long jump, single-legged hop, and 0.8-km run (P < .05) after controlling for baseline. Boys did not demonstrate similar adaptations from the INT program (P ≥ .05). Conclusions: These data indicate that INT is an effective and time-efficient addition to PE for enhancing motor skills and promoting physical activity in children. Seven-year-old girls appeared to be more sensitive to the effects of INT than 7-year-old boys. Future research is warranted to confirm these effects in larger cohorts of children. PMID:24490841

Integrative neuromuscular training and sex-specific fitness performance in 7-year-old children: an exploratory investigation.

PubMed

Faigenbaum, Avery D; Myer, Gregory D; Farrell, Anne; Radler, Tracy; Fabiano, Marc; Kang, Jie; Ratamess, Nicholas; Khoury, Jane; Hewett, Timothy E

2014-01-01

Integrative neuromuscular training (INT) has successfully enhanced physical fitness and reduced abnormal biomechanics, which appear to decrease injury rates in adolescent female athletes. If not addressed at the proper time, low levels of physical fitness and abnormal mechanics may predispose female athletes to an increased risk of musculoskeletal injuries. To evaluate sex-specific effects of INT on selected measures of health- and skill-related fitness in children during physical education (PE). Cohort study. Public primary school. Forty children (16 boys, 24 girls; age = 7.6 ± 0.3 years, height = 124.5 ± 6.4 cm, mass = 29.5 ± 7.6 kg) from 2 second-grade PE classes. The classes were randomized into the PE-plus-INT group (10 boys, 11 girls) or the control group (6 boys, 13 girls) that participated in traditional PE. The INT was performed 2 times per week during the first approximately 15 minutes of each PE class and consisted of body weight exercises. Push-up, curl-up, standing long jump, single-legged hop, single-legged balance, sit-and-reach flexibility test, shuttle run, and 0.8-km run. At baseline, the boys demonstrated higher levels of performance in most of the fitness measurements as evidenced by greater performance on the push-up, standing long jump, single-legged hop, shuttle run, and 0.8-km run (P < .05). In the evaluation of the training effects, we found intervention effects in the girls for enhanced INT-induced gains in performance relative to the control group on the curl-up, long jump, single-legged hop, and 0.8-km run (P < .05) after controlling for baseline. Boys did not demonstrate similar adaptations from the INT program (P ≥ .05). These data indicate that INT is an effective and time-efficient addition to PE for enhancing motor skills and promoting physical activity in children. Seven-year-old girls appeared to be more sensitive to the effects of INT than 7-year-old boys. Future research is warranted to confirm these effects in larger cohorts of children.

Limits to sustained energy intake. XV. Effects of wheel running on the energy budget during lactation.

PubMed

Zhao, Zhi-Jun; Król, Elzbieta; Moille, Sophie; Gamo, Yuko; Speakman, John R

2013-06-15

The capacity of animals to dissipate heat may constrain sustained energy intake during lactation. We examined these constraints at peak lactation in MF1 mice that had ad libitum access to food, or that had to run a pre-set target on running wheels to obtain ad libitum access to food. The voluntary distance run decreased sharply during pregnancy and peak lactation. When lactating females were provided with 80% of their estimated food requirements, and had to run pre-set distances of 2, 4 or 6 km before given access to additional ad libitum food, most of them did not complete the running target during late lactation and the mice with the highest targets failed to reach their targets earlier in lactation. There were consequently significant group differences in asymptotic food intake (2 km, 16.97 ± 0.40 g day(-1); 4 km, 14.29 ± 0.72 g day(-1); and 6 km, 12.65 ± 0.45 g day(-1)) and weaned litter masses (2 km, 71.11 ± 2.39 g; 4 km, 54.63 ± 4.28 g and 6 km, 47.18 ± 2.46 g). When the females did run sufficiently to gain ad libitum food access, their intake did not differ between the different distance groups or from controls that were not required to run. Thus, despite being physically capable of running the distances, mice could not exercise sufficiently in lactation to gain regular ad libitum access to food, probably because of the risks of hyperthermia when combining heat production from exercise with thermogenesis from lactation.

Shorter Ground Contact Time and Better Running Economy: Evidence From Female Kenyan Runners.

PubMed

Mooses, Martin; Haile, Diresibachew W; Ojiambo, Robert; Sang, Meshack; Mooses, Kerli; Lane, Amy R; Hackney, Anthony C

2018-06-25

Mooses, M, Haile, DW, Ojiambo, R, Sang, M, Mooses, K, Lane, AR, and Hackney, AC. Shorter ground contact time and better running economy: evidence from female Kenyan runners. J Strength Cond Res XX(X): 000-000, 2018-Previously, it has been concluded that the improvement in running economy (RE) might be considered as a key to the continued improvement in performance when no further increase in V[Combining Dot Above]O2max is observed. To date, RE has been extensively studied among male East African distance runners. By contrast, there is a paucity of data on the RE of female East African runners. A total of 10 female Kenyan runners performed 3 × 1,600-m steady-state run trials on a flat outdoor clay track (400-m lap) at the intensities that corresponded to their everyday training intensities for easy, moderate, and fast running. Running economy together with gait characteristics was determined. Participants showed moderate to very good RE at the first (202 ± 26 ml·kg·km) and second (188 ± 12 ml·kg·km) run trials, respectively. Correlation analysis revealed significant relationship between ground contact time (GCT) and RE at the second run (r = 0.782; p = 0.022), which represented the intensity of anaerobic threshold. This study is the first to report the RE and gait characteristics of East African female athletes measured under everyday training settings. We provided the evidence that GCT is associated with the superior RE of the female Kenyan runners.

The evolution of extreme precipitations in high resolution scenarios over France

NASA Astrophysics Data System (ADS)

Colin, J.; Déqué, M.; Somot, S.

2009-09-01

Over the past years, improving the modelling of extreme events and their variability at climatic time scales has become one of the challenging issue raised in the regional climate research field. This study shows the results of a high resolution (12 km) scenario run over France with the limited area model (LAM) ALADIN-Climat, regarding the representation of extreme precipitations. The runs were conducted in the framework of the ANR-SCAMPEI national project on high resolution scenarios over French mountains. As a first step, we attempt to quantify one of the uncertainties implied by the use of LAM : the size of the area on which the model is run. In particular, we address the issue of whether a relatively small domain allows the model to create its small scale process. Indeed, high resolution scenarios cannot be run on large domains because of the computation time. Therefore one needs to answer this preliminary question before producing and analyzing such scenarios. To do so, we worked in the framework of a « big brother » experiment. We performed a 23-year long global simulation in present-day climate (1979-2001) with the ARPEGE-Climat GCM, at a resolution of approximately 50 km over Europe (stretched grid). This first simulation, named ARP50, constitutes the « big brother » reference of our experiment. It has been validated in comparison with the CRU climatology. Then we filtered the short waves (up to 200 km) from ARP50 in order to obtain the equivalent of coarse resolution lateral boundary conditions (LBC). We have carried out three ALADIN-Climat simulations at a 50 km resolution with these LBC, using different configurations of the model : * FRA50, run over a small domain (2000 x 2000 km, centered over France), * EUR50, run over a larger domain (5000 x 5000 km, centered over France as well), * EUR50-SN, run over the large domain (using spectral nudging). Considering the facts that ARPEGE-Climat and ALADIN-Climat models share the same physics and dynamics and that both regional and global simulations were run at the same resolution, ARP50 can be regarded as a reference with which FRA50, EUR50 and EUR50-SN should each be compared. After an analysis of the differences between the regional simulations and ARP50 in annual and seasonal mean, we focus on the representation of rainfall extremes comparing two dimensional fields of various index inspired from STARDEX and quantile-quantile plots. The results show a good agreement with the ARP50 reference for all three regional simulations and little differences are found between them. This result indicates that the use of small domains is not significantly detrimental to the modelling of extreme precipitation events. It also shows that the spectral nudging technique has no detrimental effect on the extreme precipitation. Therefore, high resolution scenarios performed on a relatively small domain such as the ones run for SCAMPEI, can be regarded as good tools to explore their possible evolution in the future climate. Preliminary results on the response of precipitation extremes over South-East France are given.

The Reliability of a 5km Run Test on a Motorized Treadmill

ERIC Educational Resources Information Center

Driller, Matthew; Brophy-Williams, Ned; Walker, Anthony

2017-01-01

The purpose of the present study was to determine the reliability of a 5km run test on a motorized treadmill. Over three consecutive weeks, 12 well-trained runners completed three 5km time trials on a treadmill following a standardized warm-up. Runners were partially-blinded to their running speed and distance covered. Total time to complete the…

Does “Live High-Train Low (and High)” Hypoxic Training Alter Running Mechanics In Elite Team-sport Players?

PubMed Central

Girard, Olivier; Millet, Grégoire P.; Morin, Jean-Benoit; Brocherie, Franck

2017-01-01

This study aimed to investigate if “Live High-Train Low (and High)” hypoxic training alters constant-velocity running mechanics. While residing under normobaric hypoxia (≥14 h·d-1; FiO2 14.5-14.2%) for 14 days, twenty field hockey players performed, in addition to their usual training in normoxia, six sessions (4 × 5 × 5-s maximal sprints; 25 s passive recovery; 5 min rest) under either normobaric hypoxia (FiO2 ~14.5%, n = 9) or normoxia (FiO2 20.9%, n = 11). Before and immediately after the intervention, their running pattern was assessed at 10 and 15 km·h-1 as well as during six 30-s runs at ~20 km·h-1 with 30-s passive recovery on an instrumented motorised treadmill. No clear changes in running kinematics and spring-mass parameters occurred globally either at 10, 15 or ~20 km·h-1, with also no significant time × condition interaction for any parameters (p > 0.14). Independently of the condition, heart rate (all p < 0.05) and ratings of perceived exertion decreased post-intervention (only at 15 km·h-1, p < 0.05). Despite indirect signs for improved psycho-physiological responses, no forthright change in stride mechanical pattern occurred after “Live High-Train Low (and High)” hypoxic training. Key points There are indirect signs for improved psycho-physiological responses in responses to “Live High-Train Low (and High)” hypoxic training. This hypoxic training regimen, however, does not modify the running mechanics of elite team-sport players at low and high velocities. Coaches can be confident that this intervention, known for inducing significant metabolic benefits, is appropriate for athletes since their running kinetics and kinematics are not negatively affected by chronic hypoxic exposure. PMID:28912649

Running energetics in the pronghorn antelope.

PubMed

Lindstedt, S L; Hokanson, J F; Wells, D J; Swain, S D; Hoppeler, H; Navarro, V

1991-10-24

The pronghorn antelope (Antilocapra americana) has an alleged top speed of 100 km h-1, second only to the cheetah (Acionyx jubatus) among land vertebrates, a possible response to predation in the exposed habitat of the North American prairie. Unlike cheetahs, however, pronghorn antelope are distance runners rather than sprinters, and can run 11 km in 10 min, an average speed of 65 km h-1. We measured maximum oxygen uptake in pronghorn antelope to distinguish between two potential explanations for this ability: either they have evolved a uniquely high muscular efficiency (low cost of transport) or they can supply oxygen to the muscles at unusually high levels. Because the cost of transport (energy per unit distance covered per unit body mass) varies as a predictable function of body mass among terrestrial vertebrates, we can calculate the predicted cost to maintain speeds of 65 and 100 km h-1 in an average 32-kg animal. The resulting range of predicted values, 3.2-5.1 ml O2 kg-1 s-1, far surpasses the predicted maximum aerobic capacity of a 32-kg mammal (1.5 ml O2 kg-1 s-1). We conclude that their performance is achieved by an extraordinary capacity to consume and process enough oxygen to support a predicted running speed greater than 20 ms-1 (70 km h-1), attained without unique respiratory-system structures.

Comparison of the influence of age on cycling efficiency and the energy cost of running in well-trained triathletes.

PubMed

Peiffer, Jeremiah; Abbiss, Chris R; Sultana, Frederic; Bernard, Thierry; Brisswalter, Jeanick

2016-01-01

Locomotive efficiency is cited as an important component to endurance performance; however, inconsistent observations of age-related changes in efficiency question its influence in the performance of masters athletes. This study examined locomotive efficiency in young and masters triathletes during both a run and cycle test. Twenty young (28.5 ± 2.6 years) and 20 masters (59.8 ± 1.3 years) triathletes completed an incremental cycling and running test to determine maximal aerobic consumption (VO2max) and the first ventilatory threshold (VT1). Participants then completed 10-min submaximal running and cycling tests at VT1 during which locomotive efficiency was calculated from expired ventilation. Additionally, body fat percentage was determined using skin-fold assessment. During the cycle and run, VO2max was lower in the masters (48.3 ± 5.4 and 49.6 ± 4.8 ml kg(-1) min(-1), respectively) compared with young (61.6 ± 5.7 and 62.4 ± 5.2 ml kg(-1) min(-1), respectively) cohort. Maximal running speed and the cycling power output corresponding to VO2max were also lower in the masters (15.1 ± 0.8 km h(-1) and 318.6 ± 26.0 W) compared with the young (19.5 ± 1.3 km h(-1) and 383.6 ± 35.0 W) cohort. Cycling efficiency was lower (-11.2%) in the masters compared with young cohort. Similar results were observed for the energy cost of running (+10.8%); however, when scaled to lean body mass, changes were more pronounced during the run (+22.1%). Within trained triathletes, ageing can influence efficiency in both the run and cycle discipline. While disregarded in the past, efficiency should be considered in research examining performance in ageing athletes.

Short-term heat acclimation improves the determinants of endurance performance and 5-km running performance in the heat.

PubMed

James, Carl A; Richardson, Alan J; Watt, Peter W; Willmott, Ashley G B; Gibson, Oliver R; Maxwell, Neil S

2017-03-01

This study investigated the effect of 5 days of controlled short-term heat acclimation (STHA) on the determinants of endurance performance and 5-km performance in runners, relative to the impairment afforded by moderate heat stress. A control group (CON), matched for total work and power output (2.7 W·kg -1 ), differentiated thermal and exercise contributions of STHA on exercise performance. Seventeen participants (10 STHA, 7 CON) completed graded exercise tests (GXTs) in cool (13 °C, 50% relative humidity (RH), pre-training) and hot conditions (32 °C, 60% RH, pre- and post-training), as well as 5-km time trials (TTs) in the heat, pre- and post-training. STHA reduced resting (p = 0.01) and exercising (p = 0.04) core temperature alongside a smaller change in thermal sensation (p = 0.04). Both groups improved the lactate threshold (LT, p = 0.021), lactate turnpoint (LTP, p = 0.005) and velocity at maximal oxygen consumption (vV̇O 2max ; p = 0.031) similarly. Statistical differences between training methods were observed in TT performance (STHA, -6.2(5.5)%; CON, -0.6(1.7)%, p = 0.029) and total running time during the GXT (STHA, +20.8(12.7)%; CON, +9.8(1.2)%, p = 0.006). There were large mean differences in change in maximal oxygen consumption between STHA +4.0(2.2) mL·kg -1 ·min -1 (7.3(4.0)%) and CON +1.9(3.7) mL·kg -1 ·min -1 (3.8(7.2)%). Running economy (RE) deteriorated following both training programmes (p = 0.008). Similarly, RE was impaired in the cool GXT, relative to the hot GXT (p = 0.004). STHA improved endurance running performance in comparison with work-matched normothermic training, despite equality of adaptation for typical determinants of performance (LT, LTP, vV̇O 2max ). Accordingly, these data highlight the ergogenic effect of STHA, potentially via greater improvements in maximal oxygen consumption and specific thermoregulatory and associated thermal perception adaptations absent in normothermic training.

Running Technique is an Important Component of Running Economy and Performance

PubMed Central

FOLLAND, JONATHAN P.; ALLEN, SAM J.; BLACK, MATTHEW I.; HANDSAKER, JOSEPH C.; FORRESTER, STEPHANIE E.

2017-01-01

ABSTRACT Despite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques used by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated. Purpose This study aimed to determine the relationship between individual and combined kinematic measures of technique with both RE and performance. Methods Ninety-seven endurance runners (47 females) of diverse competitive standards performed a discontinuous protocol of incremental treadmill running (4-min stages, 1-km·h−1 increments). Measurements included three-dimensional full-body kinematics, respiratory gases to determine energy cost, and velocity of lactate turn point. Five categories of kinematic measures (vertical oscillation, braking, posture, stride parameters, and lower limb angles) and locomotory energy cost (LEc) were averaged across 10–12 km·h−1 (the highest common velocity < velocity of lactate turn point). Performance was measured as season's best (SB) time converted to a sex-specific z-score. Results Numerous kinematic variables were correlated with RE and performance (LEc, 19 variables; SB time, 11 variables). Regression analysis found three variables (pelvis vertical oscillation during ground contact normalized to height, minimum knee joint angle during ground contact, and minimum horizontal pelvis velocity) explained 39% of LEc variability. In addition, four variables (minimum horizontal pelvis velocity, shank touchdown angle, duty factor, and trunk forward lean) combined to explain 31% of the variability in performance (SB time). Conclusions This study provides novel and robust evidence that technique explains a substantial proportion of the variance in RE and performance. We recommend that runners and coaches are attentive to specific aspects of stride parameters and lower limb angles in part to optimize pelvis movement, and ultimately enhance performance. PMID:28263283

Voluntary resistance running wheel activity pattern and skeletal muscle growth in rats.

PubMed

Legerlotz, Kirsten; Elliott, Bradley; Guillemin, Bernard; Smith, Heather K

2008-06-01

The aims of this study were to characterize the pattern of voluntary activity of young rats in response to resistance loading on running wheels and to determine the effects of the activity on the growth of six limb skeletal muscles. Male Sprague-Dawley rats (4 weeks old) were housed individually with a resistance running wheel (R-RUN, n = 7) or a conventional free-spinning running wheel (F-RUN, n = 6) or without a wheel, as non-running control animals (CON, n = 6). The torque required to move the wheel in the R-RUN group was progressively increased, and the activity (velocity, distance and duration of each bout) of the two running wheel groups was recorded continuously for 45 days. The R-RUN group performed many more, shorter and faster bouts of running than the F-RUN group, yet the mean daily distance was not different between the F-RUN (1.3 +/- 0.2 km) and R-RUN group (1.4 +/- 0.6 km). Only the R-RUN resulted in a significantly (P < 0.05) enhanced muscle wet mass, relative to the increase in body mass, of the plantaris (23%) and vastus lateralis muscle (17%), and the plantaris muscle fibre cross-sectional area, compared with CON. Both F-RUN and R-RUN led to a significantly greater wet mass relative to increase in body mass and muscle fibre cross-sectional area in the soleus muscle compared with CON. We conclude that the pattern of voluntary activity on a resistance running wheel differs from that on a free-spinning running wheel and provides a suitable model to induce physiological muscle hypertrophy in rats.

WEEKLY RUNNING VOLUME AND RISK OF RUNNING‐RELATED INJURIES AMONG MARATHON RUNNERS

PubMed Central

Nielsen, Rasmus Oestergaard; Juul, Martin Serup; Rasmussen, Sten

2013-01-01

Purpose/Background: The purpose of this study was to investigate if the risk of injury declines with increasing weekly running volume before a marathon race. Methods: The study was a retrospective cohort study on marathon finishers. Following a marathon, participants completed a web‐based questionnaire. The outcome of interest was a self‐reported running‐related injury. The injury had to be severe enough to cause a reduction in distance, speed, duration or frequency of running for at least 14 days. Primary exposure was self‐reported average weekly volume of running before the marathon categorized into below 30 km/week, 30 to 60 km/week, and above 60 km/week. Results: A total of 68 of the 662 respondents sustained an injury. When adjusting for previous injury and previous marathons, the relative risk (RR) of suffering an injury rose by 2.02 [95% CI: 1.26; 3.24], p < 0.01, among runners with an average weekly training volume below 30 km/week compared with runners with an average weekly training volume of 30‐60 km/week. No significant differences were found between runners exceeding 60 km/week and runners running 30‐60 km/week (RR=1.13 [0.5;2.8], p=0.80). Conclusions: Runners may be advised to run a minimum of 30 km/week before a marathon to reduce their risk of running‐related injury. Level of Evidence: 2b PMID:23593549

Running stride peak forces inversely determine running economy in elite runners.

PubMed

Støren, Øyvind; Helgerud, Jan; Hoff, Jan

2011-01-01

The present study investigated the relationship between running economy (RE) at 15 km/h(-1) , 3.000-m race time, maximal strength, and a number of physiological, anthropometrical, and mechanical variables. The variables measured included RE, maximal oxygen consumption, heart rate, step length and frequency, contact time, and the peak horizontal and vertical forces of each step. Maximal strength was measured as the 1 repetition maximum (1RM) half-squat using a leg press machine. Eleven male elite endurance athletes with a V(O2)max of 75.8 ± 6.2 mL/kg(-1)/min(-1) participated in this study. After the anthropometric data were collected, they were tested for RE, running characteristics, and force measures on a level treadmill at 15 km/h(-1). The athletes wore contact soles, and the treadmill was placed on a force platform. Maximal oxygen consumption and 1RM were tested after the RE measurements. The sum of horizontal and vertical peak forces revealed a significant inverse correlation (p < 0.05) both with 3,000-m performance (R = 0.71) and RE (R = 0.66). Inverse correlations were also found (p < 0.05) between RE and body height (R = 0.61) and between RE and body fat percentage (R = 0.62). In conclusion, the sum of horizontal and vertical peak forces was found to be negatively correlated to running economy and 3,000-m running performance, indicating that avoiding vertical movements and high horizontal braking force is crucial for a positive development of RE.

Beetroot juice does not enhance altitude running performance in well-trained athletes.

PubMed

Arnold, Josh Timothy; Oliver, Samuel James; Lewis-Jones, Tammy Maria; Wylie, Lee John; Macdonald, Jamie Hugo

2015-06-01

We hypothesized that acute dietary nitrate (NO3(-)) provided as concentrated beetroot juice supplement would improve endurance running performance of well-trained runners in normobaric hypoxia. Ten male runners (mean (SD): sea level maximal oxygen uptake, 66 (7) mL·kg(-1)·min(-1); 10 km personal best, 36 (2) min) completed incremental exercise to exhaustion at 4000 m and a 10-km treadmill time-trial at 2500 m simulated altitude on separate days after supplementation with ∼7 mmol NO3(-) and a placebo at 2.5 h before exercise. Oxygen cost, arterial oxygen saturation, heart rate, and ratings of perceived exertion (RPE) were determined during the incremental exercise test. Differences between treatments were determined using means [95% confidence intervals], paired sample t tests, and a probability of individual response analysis. NO3(-) supplementation increased plasma nitrite concentration (NO3(-), 473 (226) nmol·L(-1) vs. placebo, 61 (37) nmol·L(-1), P < 0.001) but did not alter time to exhaustion during the incremental test (NO3(-), 402 (80) s vs. placebo 393 (62) s, P = 0.5) or time to complete the 10-km time-trial (NO3(-), 2862 (233) s vs. placebo, 2874 (265) s, P = 0.6). Further, no practically meaningful beneficial effect on time-trial performance was observed as the 11 [-60 to 38] s improvement was less than the a priori determined minimum important difference (51 s), and only 3 runners experienced a "likely, probable" performance improvement. NO3(-) also did not alter oxygen cost, arterial oxygen saturation, heart rate, or RPE. Acute dietary NO3(-) supplementation did not consistently enhance running performance of well-trained athletes in normobaric hypoxia.

Physiological and biological factors associated with a 24 h treadmill ultra-marathon performance.

PubMed

Millet, G Y; Banfi, J C; Kerherve, H; Morin, J B; Vincent, L; Estrade, C; Geyssant, A; Feasson, L

2011-02-01

The purpose of this study was to examine the physiological and biological factors associated with ultra-endurance performance. Fourteen male runners volunteered to run on a treadmill as many kilometers as possible over a 24-h period (24TR). Maximal oxygen uptake (VO(2max)), velocity associated with VO(2max)(VO(2max)) and running economy (RE) at 8 km/h were measured. A muscle biopsy was also performed in the vastus lateralis muscle. The subjects ran 149.2 ± 15.7 km in 18 h 39 ± 41 min of effective attendance on the treadmill, corresponding to 39.4 ± 4.2% of . Standard multiple-regression analysis showed that performance was significantly (R(2) = 0.82; P = 0.005) related to VO(2max) and specific endurance, i.e. the average speed sustained over the 24TR expressed in . VO(2max) was associated with a high capillary tortuosity (R(2) = 0.66; P = 0.01). Specific endurance was significantly related to RE and citrate synthase activity. It is concluded that a high VO(2max) and an associated developed capillary network are essential for ultra-endurance running performance. The ability to maintain a high %VO(2max) over a 24TR is another factor associated with performance and is mainly related to RE and high mitochondrial oxidative capacity in the vastus lateralis. © 2009 John Wiley & Sons A/S.

Treadmill based reference running data for healthy subjects is dependent on speed and morphological parameters.

PubMed

Schulze, Stephan; Schwesig, René; Edel, Melanie; Fieseler, Georg; Delank, Karl-Stefan; Hermassi, Souhail; Laudner, Kevin G

2017-10-01

To obtain spatiotemporal and dynamic running parameters of healthy participants and to identify relationships between running parameters, speed, and physical characteristics. A dynamometric treadmill was used to collect running data among 417 asymptomatic subjects during speeds ranging from 10 to 24km/h. Spatiotemporal and dynamic running parameters were calculated and measured. Results of the analyses showed that assessing running parameters is dependent on running speed. Body height correlated with stride length (r=0.5), cadence (r=-0.5) and plantar forefoot force (r=0.6). Body mass also had a strong relationship to plantar forefoot forces at 14 and 24km/h and plantar midfoot forces at 14 and 24km/h. This reference data base can be used in the kinematic and kinetic evaluation of running under a wide range of speeds. Copyright © 2017 Elsevier B.V. All rights reserved.

Impact of a Submaximal Warm-Up on Endurance Performance in Highly Trained and Competitive Male Runners.

PubMed

Zourdos, Michael C; Bazyler, Caleb D; Jo, Edward; Khamoui, Andy V; Park, Bong-Sup; Lee, Sang-Rok; Panton, Lynn B; Kim, Jeong-Su

2017-03-01

The purpose of this investigation was to examine the effects of a submaximal running warm-up on running performance in male endurance athletes (n = 16, M age  = 21 ± 2 years, M VO2max  = 69.3 ± 5.1 mL/kg/min). Endurance performance was determined by a 30-min distance trial after control and submaximal running warm-up conditions in a randomized crossover fashion. The warm-up began with 5 min of quiet sitting, followed by 6 min of submaximal running split into 2-min intervals at speeds corresponding to 45%, 55%, and 65% maximal oxygen consumption (VO 2 max). A 2-min walk at 3.2 km/hr concluded the 13-min warm-up protocol. For the control condition, participants sat quietly for 13 min. VO 2 and heart rate (HR) were determined at Minutes 0, 5, and 13 of the pre-exercise protocol in each condition. At the end of 13 min prior to the distance trial, mean VO 2 (warm-up = 14.1 ± 2.2 mL/kg/min vs. control = 5.5 ± 1.7 mL/kg/min) and mean HR (warm-up = 105 ± 11 bpm vs. control = 67 ± 11 bpm) were statistically greater (p < .001) in the warm-up condition compared with the control condition. The distance run did not statistically differ (p = .37) between the warm-up (7.8 ± 0.5 km) and control (7.7 ± 0.6 km) conditions; however, effect size calculation revealed a small effect (d = 0.2) in favor of the warm-up condition. Thus, the warm-up employed may have important and practical implications to determine placing among high-level athletes in close races. These findings suggest a submaximal running warm-up may have a small but critical effect on a 30-min distance trial in competitive endurance athletes. Further, the warm-up elicited increases in physiological variables VO 2 and HR prior to performance; thus, a submaximal specific warm-up should warrant consideration.

Damage to Liver and Skeletal Muscles in Marathon Runners During a 100 km Run With Regard to Age and Running Speed

PubMed Central

Jastrzębski, Zbigniew; Żychowska, Małgorzata; Radzimiński, Łukasz; Konieczna, Anna; Kortas, Jakub

2015-01-01

The purpose of this study was to determine: (1) whether damage to liver and skeletal muscles occurs during a 100 km run; (2) whether the metabolic response to extreme exertion is related to the age or running speed of the participant; (3) whether it is possible to determine the optimal running speed and distance for long-distance runners’ health by examining biochemical parameters in venous blood. Fourteen experienced male amateur ultra-marathon runners, divided into two age groups, took part in a 100 km run. Blood samples for liver and skeletal muscle damage indexes were collected from the ulnar vein just before the run, after 25, 50, 75 and 100 km, and 24 hours after termination of the run. A considerable increase in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) was observed with the distance covered (p < 0.05), which continued during recovery. An increase in the mean values of lactate dehydrogenase (LDH), creatine kinase (CK) and C-reactive protein (CRP) (p < 0.05) was observed with each sequential course. The biggest differences between the age groups were found for the activity of liver enzymes and LDH after completing 75 km as well as after 24 hours of recovery. It can be concluded that the response to extreme exertion deteriorates with age in terms of the active movement apparatus. PMID:25964813

Effect of cycling cadence on subsequent 3 km running performance in well trained triathletes

PubMed Central

Bernard, T; Vercruyssen, F; Grego, F; Hausswirth, C; Lepers, R; Vallier, J; Brisswalter, J; Vleck, V

2003-01-01

Objectives: To investigate the effect of three cycling cadences on a subsequent 3000 m track running performance in well trained triathletes. Methods: Nine triathletes completed a maximal cycling test, three cycle-run succession sessions (20 minutes of cycling + a 3000 m run) in random order, and one isolated run (3000 m). During the cycling bout of the cycle-run sessions, subjects had to maintain for 20 minutes one of the three cycling cadences corresponding to 60, 80, and 100 rpm. The metabolic intensity during these cycling bouts corresponded approximately to the cycling competition intensity of our subjects during a sprint triathlon (> 80% O2max). Results: A significant effect of the prior cycling exercise was found on middle distance running performance without any cadence effect (625.7 (40.1), 630.0 (44.8), 637.7 (57.9), and 583.0 (28.3) seconds for the 60 rpm run, 80 rpm run, 100 rpm run, and isolated run respectively). However, during the first 500 m of the run, stride rate and running velocity were significantly higher after cycling at 80 or 100 rpm than at 60 rpm (p<0.05). Furthermore, the choice of 60 rpm was associated with a higher fraction of O2max sustained during running compared with the other conditions (p<0.05). Conclusions: The results confirm the alteration in running performance completed after the cycling event compared with the isolated run. However, no significant effect of the cadence was observed within the range usually used by triathletes. PMID:12663359

The Relationship between Running Velocity and the Energy Cost of Turning during Running

PubMed Central

Hatamoto, Yoichi; Yamada, Yosuke; Sagayama, Hiroyuki; Higaki, Yasuki; Kiyonaga, Akira; Tanaka, Hiroaki

2014-01-01

Ball game players frequently perform changes of direction (CODs) while running; however, there has been little research on the physiological impact of CODs. In particular, the effect of running velocity on the physiological and energy demands of CODs while running has not been clearly determined. The purpose of this study was to examine the relationship between running velocity and the energy cost of a 180°COD and to quantify the energy cost of a 180°COD. Nine male university students (aged 18–22 years) participated in the study. Five shuttle trials were performed in which the subjects were required to run at different velocities (3, 4, 5, 6, 7, and 8 km/h). Each trial consisted of four stages with different turn frequencies (13, 18, 24 and 30 per minute), and each stage lasted 3 minutes. Oxygen consumption was measured during the trial. The energy cost of a COD significantly increased with running velocity (except between 7 and 8 km/h, p = 0.110). The relationship between running velocity and the energy cost of a 180°COD is best represented by a quadratic function (y = −0.012+0.066x +0.008x2, [r = 0.994, p = 0.001]), but is also well represented by a linear (y = −0.228+0.152x, [r = 0.991, p<0.001]). These data suggest that even low running velocities have relatively high physiological demands if the COD frequency increases, and that running velocities affect the physiological demands of CODs. These results also showed that the energy expenditure of COD can be evaluated using only two data points. These results may be useful for estimating the energy expenditure of players during a match and designing shuttle exercise training programs. PMID:24497913

Regional model simulations of New Zealand climate

NASA Astrophysics Data System (ADS)

Renwick, James A.; Katzfey, Jack J.; Nguyen, Kim C.; McGregor, John L.

1998-03-01

Simulation of New Zealand climate is examined through the use of a regional climate model nested within the output of the Commonwealth Scientific and Industrial Research Organisation nine-level general circulation model (GCM). R21 resolution GCM output is used to drive a regional model run at 125 km grid spacing over the Australasian region. The 125 km run is used in turn to drive a simulation at 50 km resolution over New Zealand. Simulations with a full seasonal cycle are performed for 10 model years. The focus is on the quality of the simulation of present-day climate, but results of a doubled-CO2 run are discussed briefly. Spatial patterns of mean simulated precipitation and surface temperatures improve markedly as horizontal resolution is increased, through the better resolution of the country's orography. However, increased horizontal resolution leads to a positive bias in precipitation. At 50 km resolution, simulated frequency distributions of daily maximum/minimum temperatures are statistically similar to those of observations at many stations, while frequency distributions of daily precipitation appear to be statistically different to those of observations at most stations. Modeled daily precipitation variability at 125 km resolution is considerably less than observed, but is comparable to, or exceeds, observed variability at 50 km resolution. The sensitivity of the simulated climate to changes in the specification of the land surface is discussed briefly. Spatial patterns of the frequency of extreme temperatures and precipitation are generally well modeled. Under a doubling of CO2, the frequency of precipitation extremes changes only slightly at most locations, while air frosts become virtually unknown except at high-elevation sites.

Multiple Off-Ice Performance Variables Predict On-Ice Skating Performance in Male and Female Division III Ice Hockey Players.

PubMed

Janot, Jeffrey M; Beltz, Nicholas M; Dalleck, Lance D

2015-09-01

The purpose of this study was to determine if off-ice performance variables could predict on-ice skating performance in Division III collegiate hockey players. Both men (n = 15) and women (n = 11) hockey players (age = 20.5 ± 1.4 years) participated in the study. The skating tests were agility cornering S-turn, 6.10 m acceleration, 44.80 m speed, modified repeat skate, and 15.20 m full speed. Off-ice variables assessed were years of playing experience, height, weight and percent body fat and off-ice performance variables included vertical jump (VJ), 40-yd dash (36.58m), 1-RM squat, pro-agility, Wingate peak power and peak power percentage drop (% drop), and 1.5 mile (2.4km) run. Results indicated that 40-yd dash (36.58m), VJ, 1.5 mile (2.4km) run, and % drop were significant predictors of skating performance for repeat skate (slowest, fastest, and average time) and 44.80 m speed time, respectively. Four predictive equations were derived from multiple regression analyses: 1) slowest repeat skate time = 2.362 + (1.68 x 40-yd dash time) + (0.005 x 1.5 mile run), 2) fastest repeat skate time = 9.762 - (0.089 x VJ) - (0.998 x 40-yd dash time), 3) average repeat skate time = 7.770 + (1.041 x 40-yd dash time) - (0.63 x VJ) + (0.003 x 1.5 mile time), and 4) 47.85 m speed test = 7.707 - (0.050 x VJ) - (0.01 x % drop). It was concluded that selected off-ice tests could be used to predict on-ice performance regarding speed and recovery ability in Division III male and female hockey players. Key pointsThe 40-yd dash (36.58m) and vertical jump tests are significant predictors of on-ice skating performance specific to speed.In addition to 40-yd dash and vertical jump, the 1.5 mile (2.4km) run for time and percent power drop from the Wingate anaerobic power test were also significant predictors of skating performance that incorporates the aspect of recovery from skating activity.Due to the specificity of selected off-ice variables as predictors of on-ice performance, coaches can elect to assess player performance off-ice and focus on other uses of valuable ice time for their individual teams.

Dose dependent effects of exercise training and detraining ontotal and regional adiposity in 4,663 men and 1,743

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Paul T.; Thompson, Paul D.

2006-01-06

Objective: To determine if exercise reduces body weight andto examine the dose-response relationships between changes in exerciseand changes in total and regional adiposity. Methods and Results:Questionnaires on weekly running distance and adiposity from a largeprospective study of 3,973 men and 1,444 women who quit running(detraining), 270 men and 146 women who started running (training) and420 men and 153 women who remained sedentary during 7.4 years offollow-up. There were significant inverse relationships between change inthe amount of vigorous exercise (km/wk run) and changes in weight and BMIin men (slope+-SE:-0.039+-0.005 kg and -0.012+-0.002 kg/m2 per km/wk,respectively) and older women (-0.060+-0.018 kg andmore » -0.022+-0.007 kg/m2per km/wk) who quit running, and in initially sedentary men(-0.098+-0.017 kg and -0.032+-0.005 kg/m2 per km/wk) and women(-0.062+-0.023 kg and -0.021+-0.008 kg/m2 per km/wk) who started running.Changes in waist circumference were also inversely related to changes inrunning distance in men who quit (-0.026+-0.005 cm per km/wk) or startedrunning (-0.078+-0.017 cm per km/wk). Conclusions. The initiation andcessation of vigorous exercise decrease and increase body weight andintra-abdominal fat, respectively, and these changes are proportional tothe change in exercise dose.« less

Effects of a capacitive-resistive electric transfer therapy on physiological and biomechanical parameters in recreational runners: A randomized controlled crossover trial.

PubMed

Duñabeitia, Iratxe; Arrieta, Haritz; Torres-Unda, Jon; Gil, Javier; Santos-Concejero, Jordan; Gil, Susana M; Irazusta, Jon; Bidaurrazaga-Letona, Iraia

2018-05-26

This study compared the effects of a capacitive-resistive electric transfer therapy (Tecar) and passive rest on physiological and biomechanical parameters in recreational runners when performed shortly after an exhausting training session. Randomized controlled crossover trial. University biomechanical research laboratory. Fourteen trained male runners MAIN OUTCOME MEASURES: Physiological (running economy, oxygen uptake, respiratory exchange ratio, ventilation, heart rate, blood lactate concentration) and biomechanical (step length; stride angle, height, frequency, and contact time; swing time; contact phase; support phase; push-off phase) parameters were measured during two incremental treadmill running tests performed two days apart after an exhaustive training session. When running at 14 km/h and 16 km/h, the Tecar treatment group presented greater increases in stride length (p < 0.001), angle (p < 0.05) and height (p < 0.001) between the first and second tests than the control group and, accordingly, greater decreases in stride frequency (p < 0.05). Physiological parameters were similar between groups. The present study suggests that a Tecar therapy intervention enhances biomechanical parameters in recreational runners after an exhaustive training session more than passive rest, generating a more efficient running pattern without affecting selected physiological parameters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sports-related dermatoses among road runners in Southern Brazil*

PubMed Central

Purim, Kátia Sheylla Malta; Leite, Neiva

2014-01-01

BACKGROUND Road running is a growing sport. OBJECTIVES: To determine the prevalence of sports-related dermatoses among road runners. METHODS Cross-sectional study of 76 road runners. Assessment was performed by means of a questionnaire, interview, and clinical examination. The chi-square and linear trend tests were used for analysis. RESULTS Most athletes were men (61%), aged 38±11 years, who ran mid- or long-distance courses (60.5%) for 45 to 60 minutes (79%), for a total of 25-64 km (42.1% ) or more than 65 km (18.4%) per week. The most prevalent injuries were blisters (50%), chafing (42.1%), calluses (34.2%), onychomadesis (31.5%), tinea pedis (18.4%), onychocryptosis (14.5%), and cheilitis simplex (14.5%). Among athletes running >64 km weekly, several conditions were significantly more frequent: calluses (p<0.04), jogger's nipple (p<0.004), cheilitis simplex (p<0.05), and tinea pedis (p<0.004). There was a significant association between the weekly running distance and the probability of skin lesions. Of the athletes in our sample, 57% trained before 10 a.m., 86% wore clothing and accessories for sun protection, 62% wore sunscreen, and 19.7% experienced sunburn. Traumatic and environmental dermatoses are common in practitioners of this outdoor sport, and are influenced by the weekly running distance. CONCLUSION In this group of athletes, rashes, blisters, sunburn, and nail disorders were recurrent complaints regardless of running distance. Calluses, athlete's foot, chapped lips, and jogger's nipple predominated in individuals who ran longer routes. PMID:25054745

Does running with or without diet changes reduce fat mass in novice runners? A 1-year prospective study.

PubMed

Nielsen, Rasmus O; Videbaek, Solvej; Hansen, Mette; Parner, Erik T; Rasmussen, Sten; Langberg, Henning

2016-01-01

The aim of this study was to explore how average weekly running distance, combined with changes in diet habits and reasons to take up running, influence fat mass. Fat mass was assessed by bioelectrical impedance at baseline and after 12 months in 538 novice runners included in a 1-year observational prospective follow-up study. During follow-up, running distance for each participant was continuously measured by GPS while reasons to take up running and diet changes were assessed trough web-based questionnaires. Loss of fat mass was compared between runners covering an average of 5 km or more per week and those running shorter distances. Runners who took up running to lose weight and ran over 5 km per week in average over a one-year period combined with a diet change reduced fat mass by -5.58 kg (95% CI: -8.69; -2.46; P<0.001). Compared with subjects also running over 5 km per week but without diet changes, the mean difference in fat mass between groups was 3.81 kg (95% CI: -5.96; -1.66; P<0.001). A difference of -3.55 kg (95% CI: -5.69; -1.41; P<0.001) was found when comparing with those running less than 5 km per week and making changes to their own diet. An average running distance of more than 5 km per week in runners who took up running to lose weight combined with a targeted diet change seems effective in reducing fat mass over a one-year period among novice runners. Still, randomized controlled trials are needed to better document the effects of self-selected diet changes.

RETURN TO RUNNING FOLLOWING A KNEE DISARTICULATION AMPUTATION: A CASE REPORT

PubMed Central

Diebal-Lee, Angela R.; Kuenzi, Robert S.; Rábago, Christopher A.

2017-01-01

Background and Purpose The evolution of running-specific prostheses has empowered athletes with lower extremity amputations to run farther and faster than previously thought possible; but running with proper mechanics is still paramount to an injury-free, active lifestyle. The purpose of this case report was to describe the successful alteration of intact limb mechanics from a Rearfoot Striking (RFS) to a Non-Rearfoot Striking (NRFS) pattern in an individual with a knee disarticulation amputation, the associated reduction in Average Vertical Loading Rate (AVLR), and the improvement in functional performance following the intervention. Case description A 30 year-old male with a traumatic right knee disarticulation amputation reported complaints of residual limb pain with running distances greater than 5 km, limiting his ability to train toward his goal of participating in triathlons. Qualitative assessment of his running mechanics revealed a RFS pattern with his intact limb and a NRFS pattern with his prosthetic limb. A full body kinematic and kinetic running analysis using 3D motion capture and force plates was performed. The average intact limb loading rate was four-times greater (112 body weights/s) than in his prosthetic limb which predisposed him to possible injury. He underwent a three week running intervention with a certified running specialist to learn a NRFS pattern with his intact limb. Outcomes Immediately following the running intervention, he was able to run distances of over 10 km without pain. On a two-mile fitness test, he decreased his run time from 19:54 min to 15:14 min. Additionally, the intact limb loading rate was dramatically reduced to 27 body weights/s, nearly identical to the prosthetic limb (24 body weights/s). Discussion This case report outlines a detailed return to run program that targets proprioceptive and neuromuscular components, injury prevention, and specificity of training strategies. The outcomes of this case report are promising as they may spur additional research toward understanding how to eliminate potential injury risk factors associated with running after limb loss. Level of Evidence 4 PMID:28900572

Hydrostatic and non-hydrostatic simulations of dense waters cascading off a shelf: The East Greenland case

NASA Astrophysics Data System (ADS)

Magaldi, Marcello G.; Haine, Thomas W. N.

2015-02-01

The cascade of dense waters of the Southeast Greenland shelf during summer 2003 is investigated with two very high-resolution (0.5-km) simulations. The first simulation is non-hydrostatic. The second simulation is hydrostatic and about 3.75 times less expensive. Both simulations are compared to a 2-km hydrostatic run, about 31 times less expensive than the 0.5 km non-hydrostatic case. Time-averaged volume transport values for deep waters are insensitive to the changes in horizontal resolution and vertical momentum dynamics. By this metric, both lateral stirring and vertical shear instabilities associated with the cascading process are accurately parameterized by the turbulent schemes used at 2-km horizontal resolution. All runs compare well with observations and confirm that the cascade is mainly driven by cyclones which are linked to dense overflow boluses at depth. The passage of the cyclones is also associated with the generation of internal gravity waves (IGWs) near the shelf. Surface fields and kinetic energy spectra do not differ significantly between the runs for horizontal scales L > 30 km. Complex structures emerge and the spectra flatten at scales L < 30 km in the 0.5-km runs. In the non-hydrostatic case, additional energy is found in the vertical kinetic energy spectra at depth in the 2 km < L < 10 km range and with frequencies around 7 times the inertial frequency. This enhancement is missing in both hydrostatic runs and is here argued to be due to the different IGW evolution and propagation offshore. The different IGW behavior in the non-hydrostatic case has strong implications for the energetics: compared to the 2-km case, the baroclinic conversion term and vertical kinetic energy are about 1.4 and at least 34 times larger, respectively. This indicates that the energy transfer from the geostrophic eddy field to IGWs and their propagation away from the continental slope is not properly represented in the hydrostatic runs.

Are physical performance and injury risk in a professional soccer team in match-play affected over a prolonged period of fixture congestion?

PubMed

Carling, C; Le Gall, F; Dupont, G

2012-01-01

In this study, the effects of a prolonged period of fixture congestion (8 successive official matches in 26 days) on physical performance and injury risk and severity in a professional soccer team were investigated. Computerised motion-analysis was used to analyse the overall distance covered and that run at light- (0.0-11.0 km·h - 1); low- (11.1-14.0 km·h - 1); moderate- (14.1-19.7 km·h - 1) and high-intensities (≥19.8 km·h - 1) for the team as a whole. Distances were measured in metres per minute. Information on match injuries was recorded prospectively. The overall distance covered varied across successive matches (p<0.001) as more distance was run in games 4 and 7 compared to 2 and 3, respectively (126.6 ± 12.3 m·min - 1 and 125.0 ± 13.2 m·min - 1 vs. 116.0 ± 8.0 m·min - 1 and 115.5 ± 11.0 m·min - 1). Distance run in light-intensity exercise also varied (p<0.001) as more distance was covered in game 4 vs. 1, 2, 3, 5 and 6 (75.5 ± 3.8 m·min - 1 vs. 70.6 ± 2.4 m·min - 1, 71.8 ± 3.4 m·min - 1, 69.3 ± 2.6 m·min - 1, 71.5 ± 3.1 m·min - 1, and 70.3 ± 2.8 m·min - 1) and in game 8 vs. game 3 (73.1 ± 3.8 vs. 69.3 ± 2.6 m·min - 1), respectively. When comparing match halves, there were no differences across games in overall or high-intensity distance covered and performance in these measures was similar for matches played before, during and after this period. Globally, no difference over the 8 games combined was observed between the reference team and opponents in any of the performance measures whereas the overall distance covered and that in low- (both p<0.001) and high-intensity running (p=0.040) differed in individual games. The incidence of match injury during the congested fixture period was similar to rates reported outside this period but the mean lay-off duration of injuries was substantially shorter during the former (p<0.05). In summary, while the overall distance run and that covered at lower intensities varied across games, high-intensity running performance and injury risk were generally unaffected during a prolonged period of fixture congestion. These results might be linked to squad rotation and post-match recovery strategies in place at the present club. © Georg Thieme Verlag KG Stuttgart · New York.

Mean platelet volume (MPV) predicts middle distance running performance.

PubMed

Lippi, Giuseppe; Salvagno, Gian Luca; Danese, Elisa; Skafidas, Spyros; Tarperi, Cantor; Guidi, Gian Cesare; Schena, Federico

2014-01-01

Running economy and performance in middle distance running depend on several physiological factors, which include anthropometric variables, functional characteristics, training volume and intensity. Since little information is available about hematological predictors of middle distance running time, we investigated whether some hematological parameters may be associated with middle distance running performance in a large sample of recreational runners. The study population consisted in 43 amateur runners (15 females, 28 males; median age 47 years), who successfully concluded a 21.1 km half-marathon at 75-85% of their maximal aerobic power (VO2max). Whole blood was collected 10 min before the run started and immediately thereafter, and hematological testing was completed within 2 hours after sample collection. The values of lymphocytes and eosinophils exhibited a significant decrease compared to pre-run values, whereas those of mean corpuscular volume (MCV), platelets, mean platelet volume (MPV), white blood cells (WBCs), neutrophils and monocytes were significantly increased after the run. In univariate analysis, significant associations with running time were found for pre-run values of hematocrit, hemoglobin, mean corpuscular hemoglobin (MCH), red blood cell distribution width (RDW), MPV, reticulocyte hemoglobin concentration (RetCHR), and post-run values of MCH, RDW, MPV, monocytes and RetCHR. In multivariate analysis, in which running time was entered as dependent variable whereas age, sex, blood lactate, body mass index, VO2max, mean training regimen and the hematological parameters significantly associated with running performance in univariate analysis were entered as independent variables, only MPV values before and after the trial remained significantly associated with running time. After adjustment for platelet count, the MPV value before the run (p = 0.042), but not thereafter (p = 0.247), remained significantly associated with running performance. The significant association between baseline MPV and running time suggest that hyperactive platelets may exert some pleiotropic effects on endurance performance.

Relationship between simulated extravehicular activity tasks and measurements of physical performance.

PubMed

Ade, C J; Broxterman, R M; Craig, J C; Schlup, S J; Wilcox, S L; Barstow, T J

2014-11-01

The purpose was to evaluate the relationships between tests of fitness and two activities that simulate components of Lunar- and Martian-based extravehicular activities (EVA). Seventy-one subjects completed two field tests: a physical abilities test and a 10km Walkback test. The relationships between test times and the following parameters were determined: running V˙O2max, gas exchange threshold (GET), speed at V˙O2max (s-V˙O2max), highest sustainable rate of aerobic metabolism [critical speed (CS)], and the finite distance that could be covered above CS (D'): arm cranking V˙O2peak, GET, critical power (CP), and the finite work that can be performed above CP (W'). CS, running V˙O2max, s-V˙O2max, and arm cranking V˙O2peak had the highest correlations with the physical abilities field test (r=0.66-0.82, P<0.001). For the 10km Walkback, CS, s-V˙O2max, and running V˙O2max were significant predictors (r=0.64-0.85, P<0.001). CS and to a lesser extent V˙O2max are most strongly associated with tasks that simulate aspects of EVA performance, highlighting CS as a method for evaluating astronaut physical capacity. Copyright © 2014 Elsevier B.V. All rights reserved.

Muscle co-activation and its influence on running performance and risk of injury in elite Kenyan runners.

PubMed

Tam, Nicholas; Santos-Concejero, Jordan; Coetzee, Devon R; Noakes, Timothy D; Tucker, Ross

2017-01-01

The relationship between muscle co-activation and energy cost of transport and risk of injury (initial loading rate and joint stiffness) has not been jointly studied. Fourteen elite Kenyan male runners were tested at two speeds (12 and 20 km · h -1 ), where oxygen consumption, kinematic, kinetic and electromyography were recorded. Electromyography of seven lower limb muscles was recorded. Pre-activation and ground contact of agonist:antagonist co-activation was determined. All muscles displayed higher activity during pre-activation except rectus femoris (RF). Conversely, no differences were found during ground contact except for higher biceps femoris (BF) at 20 km · h -1 . Knee stiffness was correlated to RF-BF co-activation during both pre-activation and ground contact at both running speeds. However, energy cost of transport was only positively correlated to the above-mentioned muscle pairs at 20 km · h -1 (r = 0620, P = 0.032; r = 0.682, P = 0.015, respectively). These findings emphasise the influence of neuromuscular control and performance and its support to musculoskeletal system to optimise function and modulate risk of injury. Further, neuromuscular activity during terminal swing is also important and necessary to execute and maintain performance.

The baseline serum value of α-amylase is a significant predictor of distance running performance.

PubMed

Lippi, Giuseppe; Salvagno, Gian Luca; Danese, Elisa; Tarperi, Cantor; La Torre, Antonio; Guidi, Gian Cesare; Schena, Federico

2015-02-01

This study was planned to investigate whether serum α-amylase concentration may be associated with running performance, physiological characteristics and other clinical chemistry analytes in a large sample of recreational athletes undergoing distance running. Forty-three amateur runners successfully concluded a 21.1 km half-marathon at 75%-85% of their maximal oxygen uptake (VO2max). Blood was drawn during warm up and 15 min after conclusion of the run. After correction for body weight change, significant post-run increases were observed for serum values of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, bilirubin, creatine kinase (CK), iron, lactate dehydrogenase (LDH), triglycerides, urea and uric acid, whereas the values of body weight, glomerular filtration rate, total and low density lipoprotein-cholesterol were significantly decreased. The concentration of serum α-amylase was unchanged. In univariate analysis, significant associations with running performance were found for gender, VO2max, training regimen and pre-run serum values of α-amylase, CK, glucose, high density lipoprotein-cholesterol, LDH, urea and uric acid. In multivariate analysis, only VO2max (p=0.042) and baseline α-amylase (p=0.021) remained significant predictors of running performance. The combination of these two variables predicted 71% of variance in running performance. The baseline concentration of serum α-amylase was positively correlated with variation of serum glucose during the trial (r=0.345; p=0.025) and negatively with capillary blood lactate at the end of the run (r=-0.352; p=0.021). We showed that the baseline serum α-amylase concentration significantly and independently predicts distance running performance in recreational runners.

Rating of perceived exertion as a tool for prescribing and self regulating interval training: a pilot study

PubMed Central

Mantuani, SS; Neiva, CM; Verardi, CEL; Pessôa-Filho, DM

2015-01-01

The aim of the present study was to analyse the usefulness of the 6-20 rating of perceived exertion (RPE) scale for prescribing and self-regulating high-intensity interval training (HIT) in young individuals. Eight healthy young subjects (age = 27.5±6.7 years) performed maximal graded exercise testing to determine their maximal and reserve heart rate (HR). Subjects then performed two HIT sessions (20 min on a treadmill) prescribed and regulated by their HR (HR: 1 min at 50% alternated with 1 min at 85% of reserve HR) or RPE (RPE: 1 minute at the 9-11 level [very light-fairly light] alternated with 1 minute at the 15-17 level [hard-very hard]) in random order. HR response and walking/running speed during the 20 min of exercise were compared between sessions. No significant difference between sessions was observed in HR during low- (HR: 135±15 bpm; RPE: 138±20 bpm) and high-intensity intervals (HR: 168±15 bpm; RPE: 170±18 bpm). Walking/running speed during low- (HR: 5.7±1.2 km · h−1; RPE: 5.7±1.3 km · h−1) and high-intensity intervals (HR: 7.8±1.9 km · h−1; RPE: 8.2±1.7 km · h−1) was also not different between sessions. No significant differences were observed in HR response and walking/running speed between HIT sessions prescribed and regulated by HR or RPE. This finding suggests that the 6-20 RPE scale may be a useful tool for prescribing and self-regulating HIT in young subjects. PMID:26028809

Specific aspects of contemporary triathlon: implications for physiological analysis and performance.

PubMed

Bentley, David J; Millet, Grégoire P; Vleck, Verónica E; McNaughton, Lars R

2002-01-01

Triathlon competitions are performed over markedly different distances and under a variety of technical constraints. In 'standard-distance' triathlons involving 1.5km swim, 40km cycling and 10km running, a World Cup series as well as a World Championship race is available for 'elite' competitors. In contrast, 'age-group' triathletes may compete in 5-year age categories at a World Championship level, but not against the elite competitors. The difference between elite and age-group races is that during the cycle stage elite competitors may 'draft' or cycle in a sheltered position; age-group athletes complete the cycle stage as an individual time trial. Within triathlons there are a number of specific aspects that make the physiological demands different from the individual sports of swimming, cycling and running. The physiological demands of the cycle stage in elite races may also differ compared with the age-group format. This in turn may influence performance during the cycle leg and subsequent running stage. Wetsuit use and drafting during swimming (in both elite and age-group races) result in improved buoyancy and a reduction in frontal resistance, respectively. Both of these factors will result in improved performance and efficiency relative to normal pool-based swimming efforts. Overall cycling performance after swimming in a triathlon is not typically affected. However, it is possible that during the initial stages of the cycle leg the ability of an athlete to generate the high power outputs necessary for tactical position changes may be impeded. Drafting during cycling results in a reduction in frontal resistance and reduced energy cost at a given submaximal intensity. The reduced energy expenditure during the cycle stage results in an improvement in running, so an athlete may exercise at a higher percentage of maximal oxygen uptake. In elite triathlon races, the cycle courses offer specific physiological demands that may result in different fatigue responses when compared with standard time-trial courses. Furthermore, it is possible that different physical and physiological characteristics may make some athletes more suited to races where the cycle course is either flat or has undulating sections. An athlete's ability to perform running activity after cycling, during a triathlon, may be influenced by the pedalling frequency and also the physiological demands of the cycle stage. The technical features of elite and age-group triathlons together with the physiological demands of longer distance events should be considered in experimental design, training practice and also performance diagnosis of triathletes.

Neuromuscular fatigue and recovery dynamics following prolonged continuous run at anaerobic threshold.

PubMed

Skof, B; Strojnik, V

2006-03-01

The aim of this study was to determine the influence of intensive aerobic running on some muscle contractile characteristics and the dynamics of their recovery during a 2 hour period afterwards. Seven well trained runners performed a 6 km run at anaerobic threshold (V(OBLA)). Knee torque during single twitch, low and high frequency electrical stimulation (ES), maximum voluntary knee extension, and muscle activation level test of the quadriceps femoris muscles were measured before and immediately after the run, and at several time points during a 120 minute interval that followed the run. After exercise, the mean (SE) maximum twitch torque (T(TW)) and torque at ES with 20 Hz (low frequency ES; T(F20)) dropped by 14.1 (5.1)% (p<0.05) and 20.6 (7.9)% (p<0.05) respectively, while torque at stimulation with 100 Hz (high frequency ES; T(F100)), maximum isometric knee extension torque (maximum voluntary contraction torque; T(MVC)), and activation level did not change significantly. Twitch contraction time was shortened by 8 (2)% (p<0.05). Ten minutes after the run, T(TW) was 40% higher than immediately after the run and 10% (p<0.05) higher than before the run. T(F20), T(F100), and T(MVC) remained lower for 60 minutes (p<0.05) than before the run. A 6 km continuous run at V(OBLA) caused peripheral fatigue by impairing excitation-contraction coupling. Twitch torque recovered very quickly. However, the process of torque restoration at maximum isometric knee extension torque and at high and low frequency ES took much longer.

Caffeine-containing energy drink improves physical performance in female soccer players.

PubMed

Lara, Beatriz; Gonzalez-Millán, Cristina; Salinero, Juan Jose; Abian-Vicen, Javier; Areces, Francisco; Barbero-Alvarez, Jose Carlos; Muñoz, Víctor; Portillo, Luis Javier; Gonzalez-Rave, Jose Maria; Del Coso, Juan

2014-05-01

There is little information about the effects of caffeine intake on female team-sport performance. The aim of this study was to investigate the effectiveness of a caffeine-containing energy drink to improve physical performance in female soccer players during a simulated game. A double-blind, placebo controlled and randomized experimental design was used in this investigation. In two different sessions, 18 women soccer players ingested 3 mg of caffeine/kg in the form of an energy drink or an identical drink with no caffeine content (placebo). After 60 min, they performed a countermovement jump (CMJ) and a 7 × 30 m sprint test followed by a simulated soccer match (2 × 40 min). Individual running distance and speed were measured using GPS devices. In comparison to the placebo drink, the ingestion of the caffeinated energy drink increased the CMJ height (26.6 ± 4.0 vs 27.4 ± 3.8 cm; P < 0.05) and the average peak running speed during the sprint test (24.2 ± 1.6 vs 24.5 ± 1.7 km/h; P < 0.05). During the simulated match, the energy drink increased the total running distance (6,631 ± 1,618 vs 7,087 ± 1,501 m; P < 0.05), the number of sprints bouts (16 ± 9 vs 21 ± 13; P < 0.05) and the running distance covered at >18 km/h (161 ± 99 vs 216 ± 103 m; P < 0.05). The ingestion of the energy drink did not affect the prevalence of negative side effects after the game. An energy drink with a dose equivalent to 3 mg of caffeine/kg might be an effective ergogenic aid to improve physical performance in female soccer players.

Acute and overuse injuries correlated to hours of training in master running athletes.

PubMed

Knobloch, Karsten; Yoon, Uzung; Vogt, Peter M

2008-07-01

The goal of the study was to determine the rate of running-associated tendinopathy in light of the amount of time training and other risk factors. 291 elite runners (average age 42 +/- 9 years) who ran an average of 65.2 +/- 28.3 km/week were included with an overall distance of 9,980,852 km (34,416 km/athlete). Descriptive statistics with Chi2-Test, Fisher-Exact-Test and Mann-Whitney-Test were used to calculate relative risks (RR). The overall injury rate was 0.08/1000 km (2.93/athlete). Overuse injuries (0.07/1000 km) were more frequent than acute injuries (0.01/1000 km). Achilles tendinopathy was the predominant injury (0.02/1000 km) followed by anterior knee pain (0.01/1000 km), and shin splints (0.01/1000 km). Achilles tendon rupture was rarely encountered (0.001/1000 km). At some time, 56.6% of the athletes had an Achilles tendon overuse injury, 46.4% anterior knee pain, 35.7% shin splints, and 12.7% had plantar fasciitis. Mid-portion Achilles tendinopathy was more common (0.01/1000 km) than insertional (0.005/1000 km). An asphalt running surface decreased mid-portion tendinopathy risk (RR 0.47, p = 0.02). In contrast, sand increased the relative risk for mid-portion Achilles tendinopathy tenfold (RR 10, CI 1.12 to 92.8, p = 0.01). Runners with more than 10 years experience had an increased risk (RR 1.6, p = 0.04) for Achilles tendinopathy. Achilles tendinopathy is the most common running-associated tendinopathy followed by runner's knee and shin splints.

Participation and performance trends in multistage ultramarathons—the ‘Marathon des Sables’ 2003–2012

PubMed Central

2012-01-01

Background The purpose of this study was to investigate participation and performance changes in the multistage ultramarathon ‘Marathon des Sables’ from 2003 to 2012. Methods Participation and performance trends in the four- or six-stage running event covering approximately 250 km were analyzed with special emphasis on the nationality and age of the athletes. The relations between gender, age, and nationality of finishers and performance were investigated using regression analyses and analysis of variance. Results Between 2003 and 2012, a number of 7,275 athletes with 938 women (12.9%) and 6,337 men (87.1%) finished the Marathon des Sables. The finisher rate in both women (r2 = 0.62) and men (r2 = 0.60) increased across years (p < 0.01). Men were significantly (p < 0.01) faster than women for overall finishers (5.9 ± 1.6 km·h−1 versus 5.1 ± 1.3 km·h−1) and for the top three finishers (12.2 ± 0.4 km·h−1 versus 8.3 ± 0.6 km·h−1). The gender difference in running speed of the top three athletes decreased (r2 = 0.72; p < 0.01) from 39.5% in 2003 to 24.1% in 2012 with a mean gender difference of 31.7 ± 2.0%. In men, Moroccans won nine of ten competitions, and one edition was won by a Jordanian athlete. In women, eight races were won by Europeans (France five, Luxembourg two, and Spain one, respectively), and two events were won by Moroccan runners. Conclusions The finisher rate in the Marathon des Sables increased this last decade. Men were significantly faster than women with a higher gender difference in performance compared to previous reports. Social or cultural inhibitions may determine the outcome in this event. Future studies need to investigate participation trends regarding nationalities and socioeconomic background, as well as the motivation to compete in ultramarathons. PMID:23849138

Voluntary running of defined distances reduces body adiposity and its associated inflammation in C57BL/6 mice fed a high-fat diet.

PubMed

Yan, Lin; Sundaram, Sneha; Nielsen, Forrest H

2017-11-01

This study investigated the effect of voluntary running of defined distances on body adiposity in male C57BL/6 mice fed a high-fat diet. Mice were assigned to 6 groups and fed a standard AIN93G diet (sedentary) or a modified high-fat AIN93G diet (sedentary; unrestricted running; or 75%, 50%, or 25% of unrestricted running) for 12 weeks. The average running distance was 8.3, 6.3, 4.2, and 2.1 km/day for the unrestricted, 75%, 50%, and 25% of unrestricted runners, respectively. Body adiposity was 46% higher in sedentary mice when fed the high-fat diet instead of the standard diet. Running decreased adiposity in mice fed the high-fat diet in a dose-dependent manner but with no significant difference between sedentary mice and those running 2.1 km/day. In sedentary mice, the high-fat instead of the standard diet increased insulin resistance, hepatic triacylglycerides, and adipose and plasma concentrations of leptin and monocyte chemotactic protein-1 (MCP-1). Running reduced these variables in a dose-dependent manner. Adipose adiponectin was lowest in sedentary mice fed the high-fat diet; running raised adiponectin in both adipose tissue and plasma. Running 8.3 and 6.3 km/day had the greatest, but similar, effects on the aforementioned variables. Running 2.1 km/day did not affect these variables except, when compared with sedentariness, it significantly decreased MCP-1. The findings showed that running 6.3 kg/day was optimal for reducing adiposity and associated inflammation that was increased in mice by feeding a high-fat diet. The findings suggest that voluntary running of defined distances may counteract the obesogenic effects of a high-fat diet.

Glomerular Filtration Rate is Unchanged By Ultramarathon.

PubMed

Wołyniec, Wojciech; Ratkowski, Wojciech; Kasprowicz, Katarzyna; Jastrzębski, Zbigniew; Małgorzewicz, Sylwia; Witek, Konrad; Grzywacz, Tomasz; Żmijewski, Piotr; Renke, Marcin

2017-12-27

Acute kidney injury (AKI) is reported as a common complication of marathon and ultramarathon running. In previous studies AKI was diagnosed on the basis of the creatinine level in serum and estimated glomerular filtration rate (eGFR). In the present study we calculated eGFR and also measured creatinine clearance after every 25 km of a 100 km run. 20 healthy, amateur runners (males, mean age 40.75 ± 7.15 years, mean weight 76.87 ± 8.39 kg) took part in a 100 km run on a track. Blood and urine were collected before the run, after every 25 km and 12 hours after the run. 17 runners completed the study. There was increase in creatinine, urea and uric acid observed after 100 km (p < 0.05). The mean increase in creatinine was 0.21 mg/dl (24.53%). 5 runners fulfilled the Acute Kidney Injury Network (AKIN) criteria of AKI. The eGFR according to the MDRD (modification of diet in renal disease), CKD-EPI (chronic kidney disease epidemiology collaboration) and Cockcroft-Gault formulas was significantly decreased after the run (p < 0.05). Otherwise, creatinine clearance calculated from creatinine level in both serum and urine remained stable. In contrast to the majority of previous studies, we did not observe any decrease in the kidney function during an ultramarathon. In this study the creatinine clearance, which is the best routine laboratory method to determine glomerular filtration rate was used. There is no evidence that long running is harmful for kidney.

Effect of Game Design, Goal Type, and Player Numbers on the Physiological and Physical Demands of Hurling-Specific Small-Sided Games.

PubMed

Malone, Shane; Collins, Kieran D

2017-06-01

The current study examined the effect that game design modification, goal type, and player numbers on the running performance and physiological demands of small-sided hurling games (SSG). Forty-eight hurling players (age, 25.5 ± 3.2 years; height, 178.9 ± 3.2 cm; body mass, 78.5 ± 4.5 kg) performed 4 types of SSG (possession [P], normal play [NP], regular goals [RG] and small goals [SG]) in 4-a-side, 5-a-side, and 6-a-side formats. Heart rate (Polar Electro Oy) and global positioning system technology (VX Sport, 4-Hz, Lower Hutt) were used to analyze the physical and physiological differences between SSG. Total distance (m), high-speed running distance (m) (≥17 km·h), very-high speed running distance (≥22 km·h) (m), peak and mean velocity (km·h) were analyzed as an indicator of the physical demands of play. The 4-a-side SSG independent of game design and goal type resulted in a significantly higher relative exercise intensity compared with 5-a-side (mean change: 6 ± 2%; p = 0.001; d = 1.9 ± 0.2; large) and 6-a-side SSG independent of game design or goal type (mean change: 12 ± 2%; p = 0.001; d = 2.9 ± 0.8; very large). The 4-a-side SG (619 ± 106-m [419-735-m]) resulted in the highest distance when compared with all PP (mean change: 141 ± 9 m; p = 0.05; d = 1.9 ± 0.3; moderate) and RG (mean change: 119 ± 39 m; p = 0.004; d = 2.1 ± 0.8; large). Similar trends were observed for 5-a-side and 6-a-side games with SG resulting in increased total running performance. In conclusion, the current observations reveal that 4-a-side NP, SG, and RG have the highest physiological demands with 4-a-side SG having increased running performance in contrast to other game design and goal-type games. Furthermore, independent of game design and goal type, 4-a-side SSG show increased relative intensity compared with 5-a-side and 6-a-side SSG.

Effects of Acutely Intermittent Hypoxic Exposure on Running Economy and Physical Performance in Basketball Players.

PubMed

Kilding, Andrew E; Dobson, Bryan P; Ikeda, Erika

2016-07-01

Kilding, AE, Dobson, BP, and Ikeda, E. Effects of acutely intermittent hypoxic exposure on running economy and physical performance in basketball players. J Strength Cond Res 30(7): 2033-2042, 2016-The aim of this study was to determine the effect of short duration intermittent hypoxic exposure (IHE) on physical performance in basketball players. Using a single-blind placebo-controlled group design, 14 trained basketball players were subjected to 15 days of passive short duration IHE (n = 7), or normoxic control (CON, n = 7), using a biofeedback nitrogen dilution device. A range of physiological, performance, and hematological variables were measured at baseline, and 10 days after IHE. After intervention, the IHE group, relative to the CON group, exhibited improvements in the Yo-Yo intermittent recovery level 1 (+4.8 ± 1.6%; effect size [ES]: 1.0 ± 0.4) and repeated high-intensity exercise test performance (-3.5 ± 1.6%; ES: -0.4 ± 0.2). Changes in hematological parameters were minimal, although soluble transferrin receptor increased after IHE (+9.2 ± 10.1%; ES: 0.3 ± 0.3). Running economy at 11 km·h (-9.0 ± 9.7%; ES: -0.7 ± 0.7) and 13 km·h was improved (-8.2 ± 6.9%; ES: -0.7 ± 0.5), but changes to V[Combining Dot Above]O2peak, HRpeak, and lactate were unclear. In summary, acutely IHE resulted in worthwhile changes in physical performance tests among competitive basketball players. However, physiological measures explaining the performance enhancement were in most part unclear.

eWaterCycle: A high resolution global hydrological model

NASA Astrophysics Data System (ADS)

van de Giesen, Nick; Bierkens, Marc; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

2014-05-01

In 2013, the eWaterCycle project was started, which has the ambitious goal to run a high resolution global hydrological model. Starting point was the PCR-GLOBWB built by Utrecht University. The software behind this model will partially be re-engineered in order to enable to run it in a High Performance Computing (HPC) environment. The aim is to have a spatial resolution of 1km x 1km. The idea is also to run the model in real-time and forecasting mode, using data assimilation. An on-demand hydraulic model will be available for detailed flow and flood forecasting in support of navigation and disaster management. The project faces a set of scientific challenges. First, to enable the model to run in a HPC environment, model runs were analyzed to examine on which parts of the program most CPU time was spent. These parts were re-coded in Open MPI to allow for parallel processing. Different parallelization strategies are thinkable. In our case, it was decided to use watershed logic as a first step to distribute the analysis. There is rather limited recent experience with HPC in hydrology and there is much to be learned and adjusted, both on the hydrological modeling side and the computer science side. For example, an interesting early observation was that hydrological models are, due to their localized parameterization, much more memory intensive than models of sister-disciplines such as meteorology and oceanography. Because it would be deadly to have to swap information between CPU and hard drive, memory management becomes crucial. A standard Ensemble Kalman Filter (enKF) would, for example, have excessive memory demands. To circumvent these problems, an alternative to the enKF was developed that produces equivalent results. This presentation shows the most recent results from the model, including a 5km x 5km simulation and a proof of concept for the new data assimilation approach. Finally, some early ideas about financial sustainability of an operational global hydrological model are presented.

Multiple Off-Ice Performance Variables Predict On-Ice Skating Performance in Male and Female Division III Ice Hockey Players

PubMed Central

Janot, Jeffrey M.; Beltz, Nicholas M.; Dalleck, Lance D.

2015-01-01

The purpose of this study was to determine if off-ice performance variables could predict on-ice skating performance in Division III collegiate hockey players. Both men (n = 15) and women (n = 11) hockey players (age = 20.5 ± 1.4 years) participated in the study. The skating tests were agility cornering S-turn, 6.10 m acceleration, 44.80 m speed, modified repeat skate, and 15.20 m full speed. Off-ice variables assessed were years of playing experience, height, weight and percent body fat and off-ice performance variables included vertical jump (VJ), 40-yd dash (36.58m), 1-RM squat, pro-agility, Wingate peak power and peak power percentage drop (% drop), and 1.5 mile (2.4km) run. Results indicated that 40-yd dash (36.58m), VJ, 1.5 mile (2.4km) run, and % drop were significant predictors of skating performance for repeat skate (slowest, fastest, and average time) and 44.80 m speed time, respectively. Four predictive equations were derived from multiple regression analyses: 1) slowest repeat skate time = 2.362 + (1.68 x 40-yd dash time) + (0.005 x 1.5 mile run), 2) fastest repeat skate time = 9.762 - (0.089 x VJ) - (0.998 x 40-yd dash time), 3) average repeat skate time = 7.770 + (1.041 x 40-yd dash time) - (0.63 x VJ) + (0.003 x 1.5 mile time), and 4) 47.85 m speed test = 7.707 - (0.050 x VJ) - (0.01 x % drop). It was concluded that selected off-ice tests could be used to predict on-ice performance regarding speed and recovery ability in Division III male and female hockey players. Key points The 40-yd dash (36.58m) and vertical jump tests are significant predictors of on-ice skating performance specific to speed. In addition to 40-yd dash and vertical jump, the 1.5 mile (2.4km) run for time and percent power drop from the Wingate anaerobic power test were also significant predictors of skating performance that incorporates the aspect of recovery from skating activity. Due to the specificity of selected off-ice variables as predictors of on-ice performance, coaches can elect to assess player performance off-ice and focus on other uses of valuable ice time for their individual teams. PMID:26336338

Statistical analysis of NWP rainfall data from Poland..

NASA Astrophysics Data System (ADS)

Starosta, Katarzyna; Linkowska, Joanna

2010-05-01

A goal of this work is to summarize the latest results of precipitation verification in Poland. In IMGW, COSMO_PL version 4.0 has been running. The model configuration is: 14 km horizontal grid spacing, initial time at 00 UTC and 12 UTC, the forecast range 72 h. The fields from the model had been verified with Polish SYNOP stations. The verification was performed using a new verification tool. For the accumulated precipitation indices FBI, POD, FAR, ETS from contingency table are calculated. In this paper the comparison of monthly and seasonal verification of 6h, 12h, 24h accumulated precipitation in 2009 is presented. Since February 2010 the model with 7 km grid spacing will be running in IMGW. The results of precipitation verification for two different models' resolution will be shown.

Outrunning major weight gain: a prospective study of 8,340consistent runners during 7 years of follow-up

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Paul T.

2006-01-06

Background: Body weight increases with aging. Short-term,longitudinal exercise training studies suggest that increasing exerciseproduces acute weight loss, but it is not clear if the maintenance oflong-term, vigorous exercise attenuates age-related weight gain inproportion to the exercise dose. Methods: Prospective study of 6,119 maleand 2,221 female runners whose running distance changed less than 5 km/wkbetween their baseline and follow-up survey 7 years later. Results: Onaverage, men who ran modest (0-24 km/wk), intermediate (24-48 km/wk) orprolonged distances (>_48 km/wk) all gained weight throughage 64,however, those who ran ?48 km/wk had one-half the average annual weightgain of those who ran<24 km/wk. Age-related weightmore » gain, and itsreduction by running, were both greater in younger than older men. Incontrast, men s gain in waist circumference with age, and its reductionby running, were the same in older and younger men. Women increased theirbody weight and waist and hip circumferences over time, regardless ofage, which was also reduced in proportion to running distance. In bothsexes, running did not attenuate weight gain uniformly, but ratherdisproportionately prevented more extreme increases. Conclusion: Men andwomen who remain vigorously active gain less weight as they age and thereduction is in proportion to the exercise dose.« less

Technical and physical analysis of the 2014 FIFA World Cup Brazil: winners vs. losers.

PubMed

Rumpf, Michael C; Silva, Joao R; Hertzog, Maxime; Farooq, Abdulaziz; Nassis, George

2017-10-01

The purpose of the present study was to investigate the technical and physical performance parameters that distinguish between teams winning and losing matches in the 2014 FIFA World Cup Brazil. Data were derived from the FIFA website and from live-statistics provided during each game of the world cup. Twelve physical (such as total distance covered in meters (TD), TD in distinct locomotor categories: low-intensity running (LIR; <11 km/h), moderate-intensity running (MIR; 11 to 14 km/h) and high-intensity-running (HIR; >14 km/h)) and 21 technical parameters (total passes, short-, medium- and long-distance passes, total pass completion rate, dangerous attacks, attacking attempts, delivery in penalty area, ball possession, goals, goals from set-pieces, goals per shot on goal, defending saves, shots, shots on goal, shot accuracy, set-pieces, crosses, corners, clearances, yellow cards) were analyzed. Forty-two games in which a winner and consequently a loser were presented after 90 minutes of game time were investigated with independent t-tests. A binary-logistic regression was utilized to investigate whether the significant variables predicted success of the winning teams. The winning teams scored significantly (P<0.05) greater amount of goals, goals per set-pieces, goals per shots on goals, shots on goal and shot accuracy and received significantly lower yellow cards. The binary-logistic regression utilized showed that shot accuracy was the best predictor for success. The physical parameters did not differ between teams winning and losing a match. Technical performance related to goal scoring parameters play a decisive role in World Cup games. Furthermore, scoring efficacy from open-play as well as from set-pieces are crucial to win matches in a World Cup tournament. At this level, physical performance was not the factor to discriminate between winners and losers.

Intercomparison of Streamflow Simulations between WRF-Hydro and Hydrology Laboratory-Research Distributed Hydrologic Model Frameworks

NASA Astrophysics Data System (ADS)

KIM, J.; Smith, M. B.; Koren, V.; Salas, F.; Cui, Z.; Johnson, D.

2017-12-01

The National Oceanic and Atmospheric Administration (NOAA)-National Weather Service (NWS) developed the Hydrology Laboratory-Research Distributed Hydrologic Model (HL-RDHM) framework as an initial step towards spatially distributed modeling at River Forecast Centers (RFCs). Recently, the NOAA/NWS worked with the National Center for Atmospheric Research (NCAR) to implement the National Water Model (NWM) for nationally-consistent water resources prediction. The NWM is based on the WRF-Hydro framework and is run at a 1km spatial resolution and 1-hour time step over the contiguous United States (CONUS) and contributing areas in Canada and Mexico. In this study, we compare streamflow simulations from HL-RDHM and WRF-Hydro to observations from 279 USGS stations. For streamflow simulations, HL-RDHM is run on 4km grids with the temporal resolution of 1 hour for a 5-year period (Water Years 2008-2012), using a priori parameters provided by NOAA-NWS. The WRF-Hydro streamflow simulations for the same time period are extracted from NCAR's 23 retrospective run of the NWM (version 1.0) over CONUS based on 1km grids. We choose 279 USGS stations which are relatively less affected by dams or reservoirs, in the domains of six different RFCs. We use the daily average values of simulations and observations for the convenience of comparison. The main purpose of this research is to evaluate how HL-RDHM and WRF-Hydro perform at USGS gauge stations. We compare daily time-series of observations and both simulations, and calculate the error values using a variety of error functions. Using these plots and error values, we evaluate the performances of HL-RDHM and WRF-Hydro models. Our results show a mix of model performance across geographic regions.

A case study of an iron-deficient female Olympic 1500-m runner.

PubMed

Pedlar, Charles R; Whyte, Gregory P; Burden, Richard; Moore, Brian; Horgan, Gill; Pollock, Noel

2013-11-01

This case study examines the impact of low serum ferritin (sFe) on physiological assessment measures and performance in a young female 1500-m runner undertaking approximately 95-130 km/wk training. The study spans 4 race seasons and an Olympic Games. During this period, 25 venous blood samples were analyzed for sFe and hemoglobin (Hb); running economy, VO(2max), and lactate threshold were measured on 6 occasions separated by 8-10 mo. Training was carefully monitored including 65 monitored treadmill training runs (targeting an intensity associated with the onset of blood lactate accumulation) using blood lactate and heart rate. Performances at competitive track events were recorded. All data were compared longitudinally. Mean sFe was 24.5 ± 7.6 μg/L (range 10-47), appearing to be in gradual decline with the exception of 2 data points (37 and 47 μg/L) after parenteral iron injections before championships, when the lowest values tended to occur, coinciding with peak training volumes. Each season, 1500-m performance improved, from 4:12.8 in year 1 to 4:03.5 in year 4. VO(2max) (69.8 ± 2.0 mL · kg(-1) · min(-1)) and running economy (%VO(2max) at a fixed speed of 16 km/h; max 87.8%, min 80.3%) were stable across time and lactate threshold improved (from 14 to 15.5 km/h). Evidence of anemia (Hb <12 g/dL) was absent. These unique data demonstrate that in 1 endurance athlete, performance can continue to improve despite an apparent iron deficiency. Raising training volume may have caused increased iron utilization; however, the effect of this on performance is unknown. Iron injections were effective in raising sFe in the short term but did not appear to affect the long-term pattern.

Influence of ABO blood group on sports performance.

PubMed

Lippi, Giuseppe; Gandini, Giorgio; Salvagno, Gian Luca; Skafidas, Spyros; Festa, Luca; Danese, Elisa; Montagnana, Martina; Sanchis-Gomar, Fabian; Tarperi, Cantor; Schena, Federico

2017-06-01

Despite being a recessive trait, the O blood group is the most frequent worldwide among the ABO blood types. Since running performance has been recognized as a major driver of evolutionary advantage in humans, we planned a study to investigate whether the ABO blood group may have an influence on endurance running performance in middle-aged recreational athletes. The study population consisted of 52 recreational, middle-aged, Caucasian athletes (mean age: 49±13 years, body mass index, 23.4±2.3 kg/m 2 ), regularly engaged in endurance activity. The athletes participated to a scientific event called "Run for Science" (R4S), entailing the completion of a 21.1 km (half-marathon) run under competing conditions. The ABO blood type status of the participants was provided by the local Service of Transfusion Medicine. In univariate analysis, running performance was significantly associated with age and weekly training, but not with body mass index. In multiple linear regression analysis, age and weekly training remained significantly associated with running performance. The ABO blood group status was also found to be independently associated with running time, with O blood type athletes performing better than those with non-O blood groups. Overall, age, weekly training and O blood group type explained 62.2% of the total variance of running performance (age, 41.6%; training regimen, 10.5%; ABO blood group, 10.1%). The results of our study show that recreational athletes with O blood group have better endurance performance compared to those with non-O blood group types. This finding may provide additional support to the putative evolutionary advantages of carrying the O blood group.

Evidence against a 40 degrees C core temperature threshold for fatigue in humans.

PubMed

Ely, Brett R; Ely, Matthew R; Cheuvront, Samuel N; Kenefick, Robert W; Degroot, David W; Montain, Scott J

2009-11-01

Evidence suggests that core temperatures of approximately 40 degrees C can induce fatigue, although this may be confounded by coincident elevations in skin temperatures and maximal cardiovascular strain. In an observational field study to examine core temperature threshold for fatigue, we investigated whether running performance is impaired when rectal temperature (T(re)) is >40 degrees C and skin temperature remains modest. Seventeen competitive runners (7/10 women/men: 8 km best 1,759 +/- 78/1,531 +/- 60 s) completed 8-km track time trials in cool (WBGT approximately 13 degrees C; n = 6), warm (WBGT approximately 27 degrees C; n = 4), or both (n = 7) conditions. T(re), chest skin temperature, and heart rate were logged continuously; elapsed time was recorded every 200 m. Running velocity for T(re) >40 degrees C was compared with that for T(re) <40 degrees C for each runner. Changes in running velocity over the last 600 m were compared between runners with T(re) >40 degrees C and <40 degrees C. Twelve runners achieved T(re) >40.0 degrees C with >or=600 m remaining (range 600-3,400 m). Average running velocity for T(re) <40 degrees C (282 +/- 27 m/min) was not different from that for T(re) >40 degrees C (279 +/- 28 m/min; P = 0.82). There were no differences in running velocity during the final 600 m between runners with final T(re) >40 degrees C or <40 degrees C (P = 0.16). Chest skin temperature ranged from 30 to 34 degrees C, and heart rate was >95% of age-predicted maximum. Our observation that runners were able to sustain running velocity despite T(re) >40 degrees C is evidence against 40 degrees C representing a "critical" core temperature limit to performance.

The influence of surface on the running velocities of elite and amateur orienteer athletes.

PubMed

Hébert-Losier, K; Jensen, K; Mourot, L; Holmberg, H-C

2014-12-01

We compared the reduction in running velocities from road to off-road terrain in eight elite and eight amateur male orienteer athletes to investigate whether this factor differentiates elite from amateur athletes. On two separate days, each subject ran three 2-km time trials and three 20-m sprints "all-out" on a road, on a path, and in a forest. On a third day, the running economy and maximal aerobic power of individuals were assessed on a treadmill. The elite orienteer ran faster than the amateur on all three surfaces and at both distances, in line with their better running economy and aerobic power. In the forest, the elites ran at a slightly higher percentage of their 2-km (∼3%) and 20-m (∼4%) road velocities. Although these differences did not exhibit traditional statistical significance, magnitude-based inferences suggested likely meaningful differences, particularly during 20-m sprinting. Of course, cognitive, mental, and physical attributes other than the ability to run on different surfaces are required for excellence in orienteering (e.g., a high aerobic power). However, we suggest that athlete-specific assessment of running performance on various surfaces and distances might assist in tailoring training and identifying individual strengths and/or weaknesses in an orienteer. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Marathon performance in relation to body fat percentage and training indices in recreational male runners.

PubMed

Tanda, Giovanni; Knechtle, Beat

2013-01-01

The purpose of this study was to investigate the effect of anthropometric characteristics and training indices on marathon race times in recreational male marathoners. Training and anthropometric characteristics were collected for a large cohort of recreational male runners (n = 126) participating in the Basel marathon in Switzerland between 2010 and 2011. Among the parameters investigated, marathon performance time was found to be affected by mean running speed and the mean weekly distance run during the training period prior to the race and by body fat percentage. The effect of body fat percentage became significant as it exceeded a certain limiting value; for a relatively low body fat percentage, marathon performance time correlated only with training indices. Marathon race time may be predicted (r = 0.81) for recreational male runners by the following equation: marathon race time (minutes) = 11.03 + 98.46 exp(-0.0053 mean weekly training distance [km/week]) + 0.387 mean training pace (sec/km) + 0.1 exp(0.23 body fat percentage [%]). The marathon race time results were valid over a range of 165-266 minutes.

Near-global climate simulation at 1 km resolution: establishing a performance baseline on 4888 GPUs with COSMO 5.0

NASA Astrophysics Data System (ADS)

Fuhrer, Oliver; Chadha, Tarun; Hoefler, Torsten; Kwasniewski, Grzegorz; Lapillonne, Xavier; Leutwyler, David; Lüthi, Daniel; Osuna, Carlos; Schär, Christoph; Schulthess, Thomas C.; Vogt, Hannes

2018-05-01

The best hope for reducing long-standing global climate model biases is by increasing resolution to the kilometer scale. Here we present results from an ultrahigh-resolution non-hydrostatic climate model for a near-global setup running on the full Piz Daint supercomputer on 4888 GPUs (graphics processing units). The dynamical core of the model has been completely rewritten using a domain-specific language (DSL) for performance portability across different hardware architectures. Physical parameterizations and diagnostics have been ported using compiler directives. To our knowledge this represents the first complete atmospheric model being run entirely on accelerators on this scale. At a grid spacing of 930 m (1.9 km), we achieve a simulation throughput of 0.043 (0.23) simulated years per day and an energy consumption of 596 MWh per simulated year. Furthermore, we propose a new memory usage efficiency (MUE) metric that considers how efficiently the memory bandwidth - the dominant bottleneck of climate codes - is being used.

Elite triathletes in 'Ironman Hawaii' get older but faster.

PubMed

Gallmann, Dalia; Knechtle, Beat; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2014-02-01

The age of peak performance has been well investigated for elite athletes in endurance events such as marathon running, but not for ultra-endurance (>6 h) events such as an Ironman triathlon covering 3.8 km swimming, 180 km cycling and 42 km running. The aim of this study was to analyze the changes in the age and performances of the annual top ten women and men at the Ironman World Championship the 'Ironman Hawaii' from 1983 to 2012. Age and performances of the annual top ten women and men in overall race time and in each split discipline were analyzed. The age of the annual top ten finishers increased over time from 26 ± 5 to 35 ± 5 years (r (2) = 0.35, P < 0.01) for women and from 27 ± 2 to 34 ± 3 years (r (2) = 0.28, P < 0.01) for men. Overall race time of the annual top ten finishers decreased across years from 671 ± 16 to 566 ± 8 min (r (2) = 0.44, P < 0.01) for women and from 583 ± 24 to 509 ± 6 min (r (2) = 0.41, P < 0.01) for men. To conclude, the age of annual top ten female and male triathletes in the 'Ironman Hawaii' increased over the last three decades while their performances improved. These findings suggest that the maturity of elite long-distance triathletes has changed during this period and raises the question of the upper limits of the age of peak performance in elite ultra-endurance performance.

Does Carbohydrate Intake During Endurance Running Improve Performance? A Critical Review.

PubMed

Wilson, Patrick B

2016-12-01

Wilson, PB. Does carbohydrate intake during endurance running improve performance? A critical review. J Strength Cond Res 30(12): 3539-3559, 2016-Previous review articles assessing the effects of carbohydrate ingestion during prolonged exercise have not focused on running. Given the popularity of distance running and the widespread use of carbohydrate supplements, this article reviewed the evidence for carbohydrate ingestion during endurance running. The criteria for inclusion were (a) experimental studies reported in English language including a performance task, (b) moderate-to-high intensity exercise >60 minutes (intermittent excluded), and (c) carbohydrate ingestion (mouth rinsing excluded). Thirty studies were identified with 76 women and 505 men. Thirteen of the 17 studies comparing a carbohydrate beverage(s) with water or a placebo found a between-condition performance benefit with carbohydrate, although heterogeneity in protocols precludes clear generalizations about the expected effect sizes. Additional evidence suggests that (a) performance benefits are most likely to occur during events >2 hours, although several studies showed benefits for tasks lasting 90-120 minutes; (b) consuming carbohydrate beverages above ad libitum levels increases gastrointestinal discomfort without improving performance; (c) carbohydrate gels do not influence performance for events lasting 16-21 km; and (d) multiple saccharides may benefit events >2 hours if intake is ≥1.3 g·min Given that most participants were fasted young men, inferences regarding women, adolescents, older runners, and those competing in fed conditions are hampered. Future studies should address these limitations to further elucidate the role of carbohydrate ingestion during endurance running.

Pilates training improves 5-km run performance by changing metabolic cost and muscle activity in trained runners

PubMed Central

Finatto, Paula; Silva, Edson Soares Da; Okamura, Alexandre B.; Almada, Bruna P.; Oliveira, Henrique B.

2018-01-01

Purpose Strength training improves distance running economy and performance. This finding is based predominantly on maximal and explosive strength programmes applied to locomotor muscles, particularly on the lower limbs. It is not certain whether a minimization of metabolic cost (Cmet) and an improvement in running performance is feasible with strength training of the postural and trunk muscles. Methods Using kinematic, neuromuscular and metabolic measurements of running at two different speeds before and after a 12-week Pilates training programme, we tested the hypothesis that core training might improve the running Cmet and performance of trained runners. Thirty-two individuals were randomly assigned to the control group (CG, n = 16) or the Pilates group (PG, n = 16). Results Confirming our hypothesis, a significant improvement (p<0.05) was observed for running performance in the PG (pre: 25.65±0.4 min; post: 23.23±0.4 min) compared to the CG (pre: 25.33±0.58 min; post: 24.61±0.52 min). Similarly, the PG (4.33±0.07 J.kg-1.m-1) had better responses than the CG (4.71±0.11 J.kg-1.m-1) during post-training for Cmet. These findings were accompanied by decreased electromyographic activity of the postural muscles at submaximal running intensities in the PG. Conclusions Overall, these results provide a rationale for selecting strength training strategies that target adaptations on specific postural and locomotor muscles for trained distance runners. PMID:29561907

Pilates training improves 5-km run performance by changing metabolic cost and muscle activity in trained runners.

PubMed

Finatto, Paula; Silva, Edson Soares Da; Okamura, Alexandre B; Almada, Bruna P; Oliveira, Henrique B; Peyré-Tartaruga, Leonardo A

2018-01-01

Strength training improves distance running economy and performance. This finding is based predominantly on maximal and explosive strength programmes applied to locomotor muscles, particularly on the lower limbs. It is not certain whether a minimization of metabolic cost (Cmet) and an improvement in running performance is feasible with strength training of the postural and trunk muscles. Using kinematic, neuromuscular and metabolic measurements of running at two different speeds before and after a 12-week Pilates training programme, we tested the hypothesis that core training might improve the running Cmet and performance of trained runners. Thirty-two individuals were randomly assigned to the control group (CG, n = 16) or the Pilates group (PG, n = 16). Confirming our hypothesis, a significant improvement (p<0.05) was observed for running performance in the PG (pre: 25.65±0.4 min; post: 23.23±0.4 min) compared to the CG (pre: 25.33±0.58 min; post: 24.61±0.52 min). Similarly, the PG (4.33±0.07 J.kg-1.m-1) had better responses than the CG (4.71±0.11 J.kg-1.m-1) during post-training for Cmet. These findings were accompanied by decreased electromyographic activity of the postural muscles at submaximal running intensities in the PG. Overall, these results provide a rationale for selecting strength training strategies that target adaptations on specific postural and locomotor muscles for trained distance runners.

The Effect of a 20 km Run on Appetite Regulation in Long Distance Runners

PubMed Central

Kojima, Chihiro; Ishibashi, Aya; Ebi, Kumiko; Goto, Kazushige

2016-01-01

The purpose of the present study was to investigate appetite-related hormonal responses and energy intake after a 20 km run in trained long distance runners. Twenty-three male long-distance runners completed two trials: either an exercise trial consisting of a 20 km outdoor run (EX) or a control trial with an identical period of rest (CON). Blood samples were collected to determine plasma acylated ghrelin, peptide YY3-36 (PYY3-36) and other hormonal and metabolite concentrations. Energy intake during a buffet test meal was also measured 30 min after the exercise or rest periods. Although plasma acylated ghrelin concentrations were significantly decreased after the 20 km run (p < 0.05), plasma PYY3-36 did not change significantly following exercise. Absolute energy intake during the buffet test meal in EX (1325 ± 55 kcal) was significantly lower than that in CON (1529 ± 55 kcal), and there was a relatively large degree of individual variability for exercise-induced changes in energy intake (−40.2% to 12.8%). However, exercise-induced changes in energy intake were not associated with plasma acylated ghrelin or PYY3-36 responses. The results demonstrated that a 20 km run significantly decreased plasma acylated ghrelin concentrations and absolute energy intake among well-trained long distance runners. PMID:27792164

Pacing during an ultramarathon running event in hilly terrain

PubMed Central

Cole-Hunter, Tom; Wiegand, Aaron N.; Solomon, Colin

2016-01-01

Purpose The dynamics of speed selection as a function of distance, or pacing, are used in recreational, competitive, and scientific research situations as an indirect measure of the psycho-physiological status of an individual. The purpose of this study was to determine pacing on level, uphill and downhill sections of participants in a long (>80 km) ultramarathon performed on trails in hilly terrain. Methods Fifteen ultramarathon runners competed in a  173 km event (five finished at  103 km) carrying a Global-Positioning System (GPS) device. Using the GPS data, we determined the speed, relative to average total speed, in level (LEV), uphill (UH) and downhill (DH) gradient categories as a function of total distance, as well as the correlation between overall performance and speed variability, speed loss, and total time stopped. Results There were no significant differences in normality, variances or means in the relative speed in 173-km and 103-km participants. Relative speed decreased in LEV, UH and DH. The main component of speed loss occurred between 5% and 50% of the event distance in LEV, and between 5% and 95% in UH and DH. There were no significant correlations between overall performance and speed loss, the variability of speed, or total time stopped. Conclusions Positive pacing was observed at all gradients, with the main component of speed loss occurring earlier (mixed pacing) in LEV compared to UH and DH. A speed reserve (increased speed in the last section) was observed in LEV and UH. The decrease in speed and variability of speed were more important in LEV and DH than in UH. The absence of a significant correlation between overall performance and descriptors of pacing is novel and indicates that pacing in ultramarathons in trails and hilly terrain differs to other types of running events. PMID:27812406

CAN RUNNERS PERCEIVE CHANGES IN HEEL CUSHIONING AS THE SHOE AGES WITH INCREASED MILEAGE?

PubMed

Cornwall, Mark W; McPoil, Thomas G

2017-08-01

For those runners who utilize footwear and have a rearfoot strike pattern, the durability of the midsole heel region has been shown to deteriorate as shoe mileage increases. The purpose of this study was threefold: 1) to determine if the runner can self-report changes in heel cushioning properties of the midsole after an extended period of distance running, 2) to determine if force and plantar pressures measured in the heel region of the midsole using a capacitance sensor insole change after running 640 km, and 3) to determine if a durometer could be used clinically to objectively measure changes in the hardness of the material in the heel region of the midsole. Cross-sectional Study. Fifteen recreational runners voluntarily consented to participate and were provided with a new pair of running shoes. Each participant's running style was observed and classified as having a rearfoot strike pattern. Inclusion criteria included running at least 24 km per week, experience running on a treadmill, no history of lower extremity congenital or traumatic deformity, or acute injury six months prior to the start of the study. The ability of each participant to self-perceive changes in shoe cushioning, comfort and fit was assessed using the Footwear Comfort Assessment Tool (FCAT). In-shoe plantar pressures and vertical forces were assessed using a capacitance sensor insole while runners ran over a 42-meter indoor runway. A Shore A durometer was used to measure the hardness of the midsole in the heel region. All measures were completed at baseline (zero km) and after running 160, 320, 480, and 640 km. In addition to descriptive statistics, a repeated measures analysis of variance was used to determine if the FCAT, pressures, forces, or midsole hardness changed because of increased running mileage. While plantar pressures and vertical forces were significantly reduced in the midsole heel region, none of the runners self-reported a significant reduction in heel cushioning based on FCAT scores after running 640 km. The use of a durometer provided an objective measure of the changes in the heel region of the midsole that closely matched the reductions observed in pressure and force values. The results indicated that runners who have a rearfoot strike pattern will have a 16% to 33% reduction in the amount of cushioning in the heel region of the midsole after running 480 km. Although there were significant reductions in heel cushioning, the experienced recreational runners in this study were not able to self-perceive these changes after running 640 km. In addition, the use of a durometer provides a quick and accurate way to assess changes in the hardness of the heel region of the midsole as running mileage increases. 3, Controlled laboratory study.

Half-marathon running performance is not improved by a rate of fluid intake above that dictated by thirst sensation in trained distance runners.

PubMed

Dion, Tommy; Savoie, Félix A; Asselin, Audrey; Gariepy, Carolanne; Goulet, Eric D B

2013-12-01

It has been demonstrated that exercise-induced dehydration (EID) does not impair, and ad libitum drinking optimizes, cycling time-trial (TT) performance. However, the idea that EID ≥ 2 % bodyweight (BW) impairs endurance performance is well ingrained. No study has tested the impact of EID upon running TT performance. We compared the effects of thirst-driven (TD) vs. programmed fluid intake (PFI) aimed at maintaining EID-associated BW loss <2 % on half-marathon performance. Ten trained distance runners underwent, in a randomized, crossover fashion, two, 21.1 km running TTs on a treadmill (30 °C, 42 % relative humidity) while facing a wind speed matching running speed and drinking water (1) according to thirst sensation (TD) or (2) to maintain BW loss <2 % of their pre-exercise BW (PFI), as recommended by the American College of Sports Medicine. Despite that PFI significantly reduced EID from 3.1 ± 0.6 (TD) to 1.3 ± 0.7 % BW (PFI), mean rectal temperature from 39.4 ± 0.4 to 39.1 ± 0.3 °C, mean body temperature from 38.1 ± 0.4 to 37.7 ± 0.2 °C and mean heart rate from 175 ± 9 to 171 ± 8 bpm, neither half-marathon time (TD 89.8 ± 7.7; PFI 89.6 ± 7.7 min) nor running pace (TD 4.3 ± 0.4; PFI 4.2 ± 0.4 min/km) differed significantly between trials. Albeit providing trivial cardiovascular and thermoregulatory advantages, in trained distance runners, PFI (1,380 ± 320 mL/h) offers no performance benefits over TD fluid intake (384 ± 180 mL/h) during a half-marathon raced under warm conditions.

Less experience and running pace are potential risk factors for medical complications during a 56 km road running race: a prospective study in 26 354 race starters--SAFER study II.

PubMed

Schwabe, Karen; Schwellnus, Martin P; Derman, Wayne; Swanevelder, Sonja; Jordaan, Esme

2014-06-01

It is important to identify risk factors associated with medical complications during ultra-marathons so that prevention programmes can be developed. To determine risk factors for medical complications during ultra-marathons. Prospective study. Two Oceans ultra-marathon (56 km) races. 26 354 race starters. Medical complications (defined as any runner requiring assessment by a doctor at the race medical facility or a local hospital on race day) were recorded over 4 years. Complications were subdivided according to the system that was affected and by final diagnosis. A Poisson regression model was used to determine risk factors for any medical complication and for more common specific complications. Risk factors for medical complications during 56 km road races were less running experience (≤1 medal vs 2-4 medals, p=0.0097), and both fastest (<6 vs 6-7 min/km, p=0.0051) and slowest (>7 vs 6-7 min/km, p<0.0001) running pace category. Year of observation was also associated with risk of complications (2009 vs 2008, p=0.0176; 2009 vs 2010, p=0.0007; 2010 vs 2011, p=0.0112). Risk factors for specific common medical complications were: postural hypotension (slowest pace), serious exercise-associated muscle cramping (older age, fastest pace), gastrointestinal complications (slowest pace) and dermatological complications (fastest pace). Less experience and running at either a slow or a fast pace were risk factors for complications during 56 km road running. Annual variation may also affect risk. Risk factors for specific medical complications were also identified. These data form the basis of further studies to assist medical staff to plan appropriate care at races.

Altered Running Economy Directly Translates to Altered Distance-Running Performance.

PubMed

Hoogkamer, Wouter; Kipp, Shalaya; Spiering, Barry A; Kram, Rodger

2016-11-01

Our goal was to quantify if small (1%-3%) changes in running economy quantitatively affect distance-running performance. Based on the linear relationship between metabolic rate and running velocity and on earlier observations that added shoe mass increases metabolic rate by ~1% per 100 g per shoe, we hypothesized that adding 100 and 300 g per shoe would slow 3000-m time-trial performance by 1% and 3%, respectively. Eighteen male sub-20-min 5-km runners completed treadmill testing, and three 3000-m time trials wearing control shoes and identical shoes with 100 and 300 g of discreetly added mass. We measured rates of oxygen consumption and carbon dioxide production and calculated metabolic rates for the treadmill tests, and we recorded overall running time for the time trials. Adding mass to the shoes significantly increased metabolic rate at 3.5 m·s by 1.11% per 100 g per shoe (95% confidence interval = 0.88%-1.35%). While wearing the control shoes, participants ran the 3000-m time trial in 626.1 ± 55.6 s. Times averaged 0.65% ± 1.36% and 2.37% ± 2.09% slower for the +100-g and +300-g shoes, respectively (P < 0.001). On the basis of a linear fit of all the data, 3000-m time increased 0.78% per added 100 g per shoe (95% confidence interval = 0.52%-1.04%). Adding shoe mass predictably degrades running economy and slows 3000-m time-trial performance proportionally. Our data demonstrate that laboratory-based running economy measurements can accurately predict changes in distance-running race performance due to shoe modifications.

The Influence of Mid-Event Deception on Psychophysiological Status and Pacing Can Persist across Consecutive Disciplines and Enhance Self-paced Multi-modal Endurance Performance

PubMed Central

Taylor, Daniel; Smith, Mark F.

2017-01-01

Purpose: To examine the effects of deceptively aggressive bike pacing on performance, pacing, and associated physiological and perceptual responses during simulated sprint-distance triathlon. Methods: Ten non-elite, competitive male triathletes completed three simulated sprint-distance triathlons (0.75 km swim, 500 kJ bike, 5 km run), the first of which established personal best “baseline” performance (BL). During the remaining two trials athletes maintained a cycling power output 5% greater than BL, before completing the run as quickly as possible. However, participants were informed of this aggressive cycling strategy before and during only one of the two trials (HON). Prior to the alternate trial (DEC), participants were misinformed that cycling power output would equal that of BL, with on-screen feedback manipulated to reinforce this deception. Results: Compared to BL, a significantly faster run performance was observed following DEC cycling (p < 0.05) but not following HON cycling (1348 ± 140 vs. 1333 ± 129 s and 1350 ± 135 s, for BL, DEC, and HON, respectively). As such, magnitude-based inferences suggest HON running was more likely to be slower, than faster, compared to BL, and that DEC running was probably faster than both BL and HON. Despite a trend for overall triathlon performance to be quicker during DEC (4339 ± 395 s) compared to HON (4356 ± 384 s), the only significant and almost certainly meaningful differences were between each of these trials and BL (4465 ± 420 s; p < 0.05). Generally, physiological and perceptual strain increased with higher cycling intensities, with little, if any, substantial difference in physiological and perceptual response during each triathlon run. Conclusions: The present study is the first to show that mid-event pace deception can have a practically meaningful effect on multi-modal endurance performance, though the relative importance of different psychophysiological and emotional responses remains unclear. Whilst our findings support the view that some form of anticipatory “template” may be used by athletes to interpret levels of psychophysiological and emotional strain, and regulate exercise intensity accordingly, they would also suggest that individual constructs such as RPE and affect may be more loosely tied with pacing than previously suggested. PMID:28174540

High Resolution Nature Runs and the Big Data Challenge

NASA Technical Reports Server (NTRS)

Webster, W. Phillip; Duffy, Daniel Q.

2015-01-01

NASA's Global Modeling and Assimilation Office at Goddard Space Flight Center is undertaking a series of very computationally intensive Nature Runs and a downscaled reanalysis. The nature runs use the GEOS-5 as an Atmospheric General Circulation Model (AGCM) while the reanalysis uses the GEOS-5 in Data Assimilation mode. This paper will present computational challenges from three runs, two of which are AGCM and one is downscaled reanalysis using the full DAS. The nature runs will be completed at two surface grid resolutions, 7 and 3 kilometers and 72 vertical levels. The 7 km run spanned 2 years (2005-2006) and produced 4 PB of data while the 3 km run will span one year and generate 4 BP of data. The downscaled reanalysis (MERRA-II Modern-Era Reanalysis for Research and Applications) will cover 15 years and generate 1 PB of data. Our efforts to address the big data challenges of climate science, we are moving toward a notion of Climate Analytics-as-a-Service (CAaaS), a specialization of the concept of business process-as-a-service that is an evolving extension of IaaS, PaaS, and SaaS enabled by cloud computing. In this presentation, we will describe two projects that demonstrate this shift. MERRA Analytic Services (MERRA/AS) is an example of cloud-enabled CAaaS. MERRA/AS enables MapReduce analytics over MERRA reanalysis data collection by bringing together the high-performance computing, scalable data management, and a domain-specific climate data services API. NASA's High-Performance Science Cloud (HPSC) is an example of the type of compute-storage fabric required to support CAaaS. The HPSC comprises a high speed Infinib and network, high performance file systems and object storage, and a virtual system environments specific for data intensive, science applications. These technologies are providing a new tier in the data and analytic services stack that helps connect earthbound, enterprise-level data and computational resources to new customers and new mobility-driven applications and modes of work. In our experience, CAaaS lowers the barriers and risk to organizational change, fosters innovation and experimentation, and provides the agility required to meet our customers' increasing and changing needs

Analysis of Running and Technical Performance in Substitute Players in International Male Rugby Union Competition.

PubMed

Lacome, Mathieu; Piscione, Julien; Hager, Jean-Philippe; Carling, Christopher

2016-09-01

To investigate the patterns and performance of substitutions in 18 international 15-a-side men's rugby union matches. A semiautomatic computerized time-motion system compiled 750 performance observations for 375 players (422 forwards, 328 backs). Running and technical-performance measures included total distance run, high-intensity running (>18.0 km/h), number of individual ball possessions and passes, percentage of passes completed, and number of attempted and percentage of successful tackles. A total of 184 substitutions (85.2%) were attributed to tactical and 32 (14.8%) to injury purposes respectively. The mean period for non-injury-purpose substitutions in backs (17.7%) occurred between 70 and 75 min, while forward substitutions peaked equally between 50-55 and 60-65 min (16.4%). Substitutes generally demonstrated improved running performance compared with both starter players who completed games and players whom they replaced (small differences, ES -0.2 to 0.5) in both forwards and backs over their entire time played. There was also a trend for better running performance in forward and back substitutes over their first 10 min of play compared with the final 10 min for replaced players (small to moderate differences, ES 0.3-0.6). Finally, running performance in both forward and back substitutes was generally lower (ES -0.1 to 0.3, unclear or small differences) over their entire 2nd-half time played compared with their first 10 min of play. The impact of substitutes on technical performance was generally considered unclear. This information provides practitioners with practical data relating to the physical and technical contributions of substitutions that subsequently could enable optimization of their impact on match play.

Effect of speed endurance and strength training on performance, running economy and muscular adaptations in endurance-trained runners.

PubMed

Vorup, Jacob; Tybirk, Jonas; Gunnarsson, Thomas P; Ravnholt, Tanja; Dalsgaard, Sarah; Bangsbo, Jens

2016-07-01

To investigate the effects of combined strength and speed endurance (SE) training along with a reduced training volume on performance, running economy and muscular adaptations in endurance-trained runners. Sixteen male endurance runners (VO2-max: ~60 ml kg(-1) min(-1)) were randomly assigned to either a combined strength and SE training (CSS; n = 9) or a control (CON; n = 7) group. For 8 weeks, CSS replaced their normal moderate-intensity training (~63 km week(-1)) with SE (2 × week(-1)) and strength training (2 × week(-1)) as well as aerobic high (1 × week(-1)) and moderate (1 × week(-1)) intensity training with a reduction in total volume of ~58 %, whereas CON continued their training (~45 km week(-1)). In CSS, 400-m and Yo-Yo intermittent recovery test performance was improved by 5 % (P < 0.01) and 19 % (P < 0.001), respectively, during the intervention period. Maximal aerobic speed was 0.6 km h(-1) higher (P < 0.05), and maximal activity of lactate dehydrogenase subunits 1 and 2 was 17 % (P < 0.05) higher after compared to before the intervention period. Time to exhaustion and peak blood lactate during an incremental treadmill test was 9 % (P < 0.05) and 32 % (P < 0.01), respectively, higher and expression of Na(+)-K(+) pump β1 subunit was 15 % higher (P < 0.05) after compared to before the intervention period. 10-K performance, maximum oxygen uptake and running economy were unchanged. In CON, no changes were observed. Adding strength and speed endurance training, along with a reduced training volume, can improve short-term exercise capacity and induce muscular adaptations related to anaerobic capacity in endurance-trained runners.

The Influence of Carbohydrate Mouth Rinse on Self-Selected Intermittent Running Performance.

PubMed

Rollo, Ian; Homewood, George; Williams, Clyde; Carter, James; Goosey-Tolfrey, Vicky L

2015-12-01

This study investigated the influence of mouth rinsing a carbohydrate solution on self-selected intermittent variable-speed running performance. Eleven male amateur soccer players completed a modified version of the Loughborough Intermittent Shuttle Test (LIST) on 2 occasions separated by 1 wk. The modified LIST allowed the self-selection of running speeds during Block 6 of the protocol (75-90 min). Players rinsed and expectorated 25 ml of noncaloric placebo (PLA) or 10% maltodextrin solution (CHO) for 10 s, routinely during Block 6 of the LIST. Self-selected speeds during the walk and cruise phases of the LIST were similar between trials. Jogging speed was significantly faster during the CHO (11.3 ± 0.7 km · h(-1)) than during the PLA trial (10.5 ± 1.3 km · h(-1)) (p = .010); 15-m sprint speeds were not different between trials (PLA: 2.69 ± 0.18 s: CHO: 2.65 ± 0.13 s) (F(2, 10), p = .157), but significant benefits were observed for sprint distance covered (p = .024). The threshold for the smallest worthwhile change in sprint performance was set at 0.2 s. Inferential statistical analysis showed the chance that CHO mouth rinse was beneficial, negligible, or detrimental to repeated sprint performance was 86%, 10%, and 4%, respectively. In conclusion, mouth rinsing and expectorating a 10% maltodextrin solution was associated with a significant increase in self-selected jogging speed. Repeated 15-m sprint performance was also 86% likely to benefit from routinely mouth rinsing a carbohydrate solution in comparison with a taste-matched placebo.

Effect of whey protein hydrolysate on performance and recovery of top-class orienteering runners.

PubMed

Hansen, Mette; Bangsbo, Jens; Jensen, Jørgen; Bibby, Bo Martin; Madsen, Klavs

2015-04-01

This trial aimed to examine the effect of whey protein hydrolysate intake before and after exercise sessions on endurance performance and recovery in elite orienteers during a training camp. Eighteen elite orienteers participated in a randomized controlled intervention trial during a 1-week training camp (13 exercise sessions). Half of the runners (PRO-CHO) ingested a protein drink before (0.3 g kg(-1)) and a protein-carbohydrate drink after (0.3 g protein kg(-1) and 1 g carbohydrate kg(-1)) each exercise session. The others ingested energy and time-matched carbohydrate drinks (CHO). A 4-km run-test with 20 control points was performed before and on the last day of the intervention. Blood and saliva were obtained in the mornings, before and after run-tests, and after the last training session. During the intervention, questionnaires were fulfilled regarding psychological sense of performance capacity and motivation. PRO-CHO and not CHO improved performance in the 4-km run-test (interaction p < .05). An increase in serum creatine kinase was observed during the week, which was greater in CHO than PRO-CHO (interaction p < .01). Lactate dehydrogenase (p < .001) and cortisol (p = .057) increased during the week, but the change did not differ between groups. Reduction in sense of performance capacity during the intervention was greater in CHO (p < .05) than PRO-CHO. In conclusion, ingestion of whey protein hydrolysate before and after each exercise session improves performance and reduces markers of muscle damage during a strenuous 1-week training camp. The results indicate that protein supplementation in conjunction with each exercise session facilitates the recovery from strenuous training in elite orienteers.

Muscle activities during walking and running at energetically optimal transition speed under normobaric hypoxia on gradient slopes

PubMed Central

Fukuoka, Yoshiyuki; Horiuchi, Masahiro

2017-01-01

Energy cost of transport per unit distance (CoT; J·kg-1·km-1) displays a U-shaped fashion in walking and a linear fashion in running as a function of gait speed (v; km·h-1). There exists an intersection between U-shaped and linear CoT-v relationships, being termed energetically optimal transition speed (EOTS; km·h-1). Combined effects of gradient and moderate normobaric hypoxia (15.0% O2) were investigated when walking and running at the EOTS in fifteen young males. The CoT values were determined at eight walking speeds (2.4–7.3 km·h-1) and four running speeds (7.3–9.4 km·h-1) on level and gradient slopes (±5%) at normoxia and hypoxia. Since an alteration of tibialis anterior (TA) activity has been known as a trigger for gait transition, electromyogram was recorded from TA and its antagonists (gastrocnemius medialis (GM) and gastrocnemius lateralis (GL)) for about 30 steps during walking and running corresponding to the individual EOTS in each experimental condition. Mean power frequency (MPF; Hz) of each muscle was quantified to evaluate alterations of muscle fiber recruitment pattern. The EOTS was not significantly different between normoxia and hypoxia on any slopes (ranging from 7.412 to 7.679 km·h-1 at normoxia and 7.516 to 7.678 km·h-1 at hypoxia) due to upward shifts (enhanced metabolic rate) of both U-shaped and linear CoT-v relationships at hypoxia. GM, but not GL, activated more when switching from walking to running on level and gentle downhill slopes. Significant decreases in the muscular activity and/or MPF were observed only in the TA when switching the gait pattern. Taken together, the EOTS was not slowed by moderate hypoxia in the population of this study. Muscular activities of lower leg extremities and those muscle fiber recruitment patterns are dependent on the gradient when walking and running at the EOTS. PMID:28301525

Yo-Yo IR1 vs. incremental continuous running test for prediction of 3000-m performance.

PubMed

Schmitz, Boris; Klose, Andreas; Schelleckes, Katrin; Jekat, Charlotte M; Krüger, Michael; Brand, Stefan-Martin

2017-11-01

This study aimed to compare physiological responses during the Yo-Yo intermittent recovery level 1 (Yo-Yo IR1) Test and an incremental continuous running field Test (ICRT) and to analyze their predictive value on 3000-m running performance. Forty moderately trained individuals (18 females) performed the ICRT and Yo-Yo IR1 Test to exhaustion. The ICRT was performed as graded running test with an increase of 2.0 km·h-1 after each 3 min interval for lactate diagnostic. In both tests, blood lactate levels were determined after the test and at 2 and 5 min of recovery. Heart rate (HR) was recorded to monitor differences in HR slopes and HR recovery. Comparison revealed a correlation between ICRT and Yo-Yo IR1 Test performance (R2=0.83, P<0.001), while significant differences in HRmax existed (Yo-Yo IR1, 189±10 bpm; ICRT, 195±16 bpm; P<0.005; ES=0.5). Maximum lactate levels were also different between test (Yo-Yo IR1, 10.1±2.1 mmol∙L-1; ICRT, 11.7±2.4 mmol∙L-1; P<0.01; ES=0.7). Significant inverse correlations were found between the Yo-Yo IR1 Test performance and 3000 m running time (R2=0.77, P<0.0001) as well as the ICRT and 3000 m time (R2=0.90, P<0.0001). Our data suggest that ICRT and Yo-Yo IR1 test are useful field test methods for the prediction of competitive running performances such as 3000-m runs but maximum HR and blood lactate values differ significantly. The ICRT may have higher predictive power for middle- to long- distance running performance such as 3000-m runs offering a reliable test for coaches in the recruitment of athletes or supervision of training concepts.

Pre-game perceived wellness highly associates with match running performances during an international field hockey tournament.

PubMed

Ihsan, Mohammed; Tan, Frankie; Sahrom, Sofyan; Choo, Hui Cheng; Chia, Michael; Aziz, Abdul Rashid

2017-06-01

This study examined the associations between pre-game wellness and changes in match running performance normalised to either (i) playing time, (ii) post-match RPE or (iii) both playing time and post-match RPE, over the course of a field hockey tournament. Twelve male hockey players were equipped with global positioning system (GPS) units while competing in an international tournament (six matches over 9 days). The following GPS-derived variables, total distance (TD), low-intensity activity (LIA; <15 km/h), high-intensity running (HIR; >15 km/h), high-intensity accelerations (HIACC; >2 m/s 2 ) and decelerations (HIDEC; >-2 m/s 2 ) were acquired and normalised to either (i) playing time, (ii) post-match RPE or (iii) both playing time and post-match RPE. Each morning, players completed ratings on a 0-10 scale for four variables: fatigue, muscle soreness, mood state and sleep quality, with cumulative scores determined as wellness. Associations between match performances and wellness were analysed using Pearson's correlation coefficient. Combined time and RPE normalisation demonstrated the largest associations with Δwellness compared with time or RPE alone for most variables; TD (r = -0.95; -1.00 to -0.82, p = .004), HIR (r = -0.95; -1.00 to -0.83, p = .003), LIA (r = -0.94; -1.00 to -0.81, p = .026), HIACC (r = -0.87; -1.00 to -0.66, p = .004) and HIDEC (r = -0.90; -0.99 to -0.74, p = .008). These findings support the use of wellness measures as a pre-match tool to assist with managing internal load over the course of a field hockey tournament. Highlights Fixtures during international field hockey tournaments are typically congested and impose high physiological demands on an athlete. To minimise decrements in running performance over the course of a tournament, measures to identify players who have sustained high internal loads are logically warranted. The present study examined the association between changes in simple customised psychometric wellness measures, on changes in match running performance normalised to (i) playing time, (ii) post-match RPE and (iii) playing time and post-match RPE, over the course of a field hockey tournament. Changes in match running performance were better associated to changes in wellness (r = -0.87 to -0.95), when running performances were normalised to both time and RPE compared with time or RPE alone. The present findings support the use of wellness measures as a pre-match tool to assist with managing internal load over the course of a field hockey tournament. Improved associations between wellness scores and match running performances were evident, when running variables were normalised to both playing time and post-match RPE.

Effect of training in minimalist footwear on oxygen consumption during walking and running

PubMed Central

Judge, LW

2015-01-01

The present study sought to examine the effect of 5 weeks of training with minimalist footwear on oxygen consumption during walking and running. Thirteen college-aged students (male n = 7, female n = 6, age: 21.7±1.4 years, height: 168.9±8.8 cm, weight: 70.4±15.8 kg, VO2max: 46.6±6.6 ml·kg−1·min−1) participated in the present investigation. The participants did not have experience with minimalist footwear. Participants underwent metabolic testing during walking (5.6 km·hr−1), light running (7.2 km·hr−1), and moderate running (9.6 km·hr−1). The participants completed this assessment barefoot, in running shoes, and in minimalist footwear in a randomized order. The participants underwent 5 weeks of training with the minimalist footwear. Afterwards, participants repeated the metabolic testing. Data was analyzed via repeated measures ANOVA. The analysis revealed a significant (F4,32= 7.576, ηp2=0.408, p ≤ 0.001) interaction effect (time × treatment × speed). During the initial assessment, the minimalist footwear condition resulted in greater oxygen consumption at 9.6 km·hr−1 (p ≤ 0.05) compared to the barefoot condition, while the running shoe condition resulted in greater oxygen consumption than both the barefoot and minimalist condition at 7.2 and 9.6 km·hr−1. At post-testing the minimalist footwear was not different at any speed compared to the barefoot condition (p> 0.12). This study suggests that initially minimalist footwear results in greater oxygen consumption than running barefoot, however; with utilization the oxygen consumption becomes similar. PMID:26060339

Effect of training in minimalist footwear on oxygen consumption during walking and running.

PubMed

Bellar, D; Judge, L W

2015-06-01

The present study sought to examine the effect of 5 weeks of training with minimalist footwear on oxygen consumption during walking and running. Thirteen college-aged students (male n = 7, female n = 6, age: 21.7±1.4 years, height: 168.9±8.8 cm, weight: 70.4±15.8 kg, VO2max: 46.6±6.6 ml·kg(-1)·min(-1)) participated in the present investigation. The participants did not have experience with minimalist footwear. Participants underwent metabolic testing during walking (5.6 km·hr(-1)), light running (7.2 km·hr(-1)), and moderate running (9.6 km·hr(-1)). The participants completed this assessment barefoot, in running shoes, and in minimalist footwear in a randomized order. The participants underwent 5 weeks of training with the minimalist footwear. Afterwards, participants repeated the metabolic testing. Data was analyzed via repeated measures ANOVA. The analysis revealed a significant (F4,32= 7.576, [Formula: see text]=0.408, p ≤ 0.001) interaction effect (time × treatment × speed). During the initial assessment, the minimalist footwear condition resulted in greater oxygen consumption at 9.6 km·hr(-1) (p ≤ 0.05) compared to the barefoot condition, while the running shoe condition resulted in greater oxygen consumption than both the barefoot and minimalist condition at 7.2 and 9.6 km·hr(-1). At post-testing the minimalist footwear was not different at any speed compared to the barefoot condition (p> 0.12). This study suggests that initially minimalist footwear results in greater oxygen consumption than running barefoot, however; with utilization the oxygen consumption becomes similar.

Matching optical flow to motor speed in virtual reality while running on a treadmill

PubMed Central

Lafortuna, Claudio L.; Mugellini, Elena; Abou Khaled, Omar

2018-01-01

We investigated how visual and kinaesthetic/efferent information is integrated for speed perception in running. Twelve moderately trained to trained subjects ran on a treadmill at three different speeds (8, 10, 12 km/h) in front of a moving virtual scene. They were asked to match the visual speed of the scene to their running speed–i.e., treadmill’s speed. For each trial, participants indicated whether the scene was moving slower or faster than they were running. Visual speed was adjusted according to their response using a staircase until the Point of Subjective Equality (PSE) was reached, i.e., until visual and running speed were perceived as equivalent. For all three running speeds, participants systematically underestimated the visual speed relative to their actual running speed. Indeed, the speed of the visual scene had to exceed the actual running speed in order to be perceived as equivalent to the treadmill speed. The underestimation of visual speed was speed-dependent, and percentage of underestimation relative to running speed ranged from 15% at 8km/h to 31% at 12km/h. We suggest that this fact should be taken into consideration to improve the design of attractive treadmill-mediated virtual environments enhancing engagement into physical activity for healthier lifestyles and disease prevention and care. PMID:29641564

Matching optical flow to motor speed in virtual reality while running on a treadmill.

PubMed

Caramenti, Martina; Lafortuna, Claudio L; Mugellini, Elena; Abou Khaled, Omar; Bresciani, Jean-Pierre; Dubois, Amandine

2018-01-01

We investigated how visual and kinaesthetic/efferent information is integrated for speed perception in running. Twelve moderately trained to trained subjects ran on a treadmill at three different speeds (8, 10, 12 km/h) in front of a moving virtual scene. They were asked to match the visual speed of the scene to their running speed-i.e., treadmill's speed. For each trial, participants indicated whether the scene was moving slower or faster than they were running. Visual speed was adjusted according to their response using a staircase until the Point of Subjective Equality (PSE) was reached, i.e., until visual and running speed were perceived as equivalent. For all three running speeds, participants systematically underestimated the visual speed relative to their actual running speed. Indeed, the speed of the visual scene had to exceed the actual running speed in order to be perceived as equivalent to the treadmill speed. The underestimation of visual speed was speed-dependent, and percentage of underestimation relative to running speed ranged from 15% at 8km/h to 31% at 12km/h. We suggest that this fact should be taken into consideration to improve the design of attractive treadmill-mediated virtual environments enhancing engagement into physical activity for healthier lifestyles and disease prevention and care.

Effect of Compression Garments on Physiological Responses After Uphill Running.

PubMed

Struhár, Ivan; Kumstát, Michal; Králová, Dagmar Moc

2018-03-01

Limited practical recommendations related to wearing compression garments for athletes can be drawn from the literature at the present time. We aimed to identify the effects of compression garments on physiological and perceptual measures of performance and recovery after uphill running with different pressure and distributions of applied compression. In a random, double blinded study, 10 trained male runners undertook three 8 km treadmill runs at a 6% elevation rate, with the intensity of 75% VO2max while wearing low, medium grade compression garments and high reverse grade compression. In all the trials, compression garments were worn during 4 hours post run. Creatine kinase, measurements of muscle soreness, ankle strength of plantar/dorsal flexors and mean performance time were then measured. The best mean performance time was observed in the medium grade compression garments with the time difference being: medium grade compression garments vs. high reverse grade compression garments. A positive trend in increasing peak torque of plantar flexion (60º·s-1, 120º·s-1) was found in the medium grade compression garments: a difference between 24 and 48 hours post run. The highest pain tolerance shift in the gastrocnemius muscle was the medium grade compression garments, 24 hour post run, with the shift being +11.37% for the lateral head and 6.63% for the medial head. In conclusion, a beneficial trend in the promotion of running performance and decreasing muscle soreness within 24 hour post exercise was apparent in medium grade compression garments.

Testing CMAQ chemistry sensitivities in base case and emissions control runs at SEARCH and SOS99 surface sites in the southeastern US

NASA Astrophysics Data System (ADS)

Arnold, J. R.; Dennis, Robin L.

CMAQ was run to simulate urban and regional tropospheric conditions in the southeastern US over 14 days in July 1999 at 32, 8 and 2 km grid spacings. Runs were made with either of two older mechanisms, Carbon Bond IV (CB4) and the Regional Acid Deposition Model, version 2 (RADM2), and with the more recent and complete California Statewide Air Pollution Research Center, version 1999 mechanism (SAPRC99) in a sensitivity matrix with a full emissions base case and separate 50% control scenarios for emissions of nitrogen oxides (NO X) and volatile organic compounds (VOC). Results from the base case were compared to observations at the Southeastern Aerosol Research and Characterization Study (SEARCH) site at Jefferson Street in Atlanta, GA (JST) and the Southern Oxidant Study (SOS) Cornelia Fort Airpark (CFA) site downwind of Nashville, TN. In the base case, SAPRC99 predicted more ozone (O 3) than CB4 or RADM2 almost every hour and especially for afternoon maxima at both JST and CFA. Performance of the 8 km models at JST was better than that of the 32 km ones for all chemistries, reducing the 1 h peak bias by as much as 30 percentage points; at CFA only the RADM2 8 km model improved. The 2 km solutions did not show improved performance over the 8 km ones at either site, with normalized 1 h bias in the peak O 3 ranging from 21% at CFA to 43% at JST. In the emissions control cases, SAPRC99 was generally more responsive than CB4 and RADM2 to NO X and VOC controls, excepting hours at JST with predicted increased O 3 from NO X control. Differential sensitivity to chemical mechanism varied by more than ±10% for NO X control at JST and CFA, and in a similar range for VOC control at JST. VOC control at the more strongly NO X- limited urban CFA site produced a differential sensitivity response of <5%. However, even when differential sensitivities in control cases were small, neither their sign nor their magnitude could be reliably determined from model performance in the full emissions case, meaning that the degree of O 3 response to a change in chemical mechanism can differ substantially with the level of precursor emissions. Hence we conclude that properly understanding the effects of changes in a model's chemical mechanism always requires emissions control cases as part of model sensitivity analysis.

Cumulative loads increase at the knee joint with slow-speed running compared to faster running: a biomechanical study.

PubMed

Petersen, Jesper; Sørensen, Henrik; Nielsen, Rasmus Østergaard

2015-04-01

Biomechanical cross-sectional study. To investigate the hypothesis that the cumulative load at the knee during running increases as running speed decreases. The knee joint load per stride decreases as running speed decreases. However, by decreasing running speed, the number of strides per given distance is increased. Running a given distance at a slower speed may increase the cumulative load at the knee joint compared with running the same distance at a higher speed, hence increasing the risk of running-related injuries in the knee. Kinematic and ground reaction force data were collected from 16 recreational runners, during steady-state running with a rearfoot strike pattern at 3 different speeds (mean ± SD): 8.02 ± 0.17 km/h, 11.79 ± 0.21 km/h, and 15.78 ± 0.22 km/h. The cumulative load (cumulative impulse) over a 1000-m distance was calculated at the knee joint on the basis of a standard 3-D inverse-dynamics approach. Based on a 1000-m running distance, the cumulative load at the knee was significantly higher at a slow running speed than at a high running speed (relative difference, 80%). The mean load per stride at the knee increased significantly across all biomechanical parameters, except impulse, following an increase in running speed. Slow-speed running decreases knee joint loads per stride and increases the cumulative load at the knee joint for a given running distance compared to faster running. The primary reason for the increase in cumulative load at slower speeds is an increase in number of strides needed to cover the same distance.

An evaluation of the physiological demands of elite rugby union using Global Positioning System tracking software.

PubMed

Cunniffe, Brian; Proctor, Wayne; Baker, Julien S; Davies, Bruce

2009-07-01

The current case study attempted to document the contemporary demands of elite rugby union. Players (n = 2) were tracked continuously during a competitive team selection game using Global Positioning System (GPS) software. Data revealed that players covered on average 6,953 m during play (83 minutes). Of this distance, 37% (2,800 m) was spent standing and walking, 27% (1,900 m) jogging, 10% (700 m) cruising, 14% (990 m) striding, 5% (320 m) high-intensity running, and 6% (420 m) sprinting. Greater running distances were observed for both players (6.7% back; 10% forward) in the second half of the game. Positional data revealed that the back performed a greater number of sprints (>20 km x h(-1)) than the forward (34 vs. 19) during the game. Conversely, the forward entered the lower speed zone (6-12 km x h(-1)) on a greater number of occasions than the back (315 vs. 229) but spent less time standing and walking (66.5 vs. 77.8%). Players were found to perform 87 moderate-intensity runs (>14 km x h(-1)) covering an average distance of 19.7 m (SD = 14.6). Average distances of 15.3 m (back) and 17.3 m (forward) were recorded for each sprint burst (>20 km x h(-1)), respectively. Players exercised at approximately 80 to 85% VO2max during the course of the game with a mean heart rate of 172 b x min(-1) ( approximately 88% HRmax). This corresponded to an estimated energy expenditure of 6.9 and 8.2 MJ, back and forward, respectively. The current study provides insight into the intense and physical nature of elite rugby using "on the field" assessment of physical exertion. Future use of this technology may help practitioners in design and implementation of individual position-specific training programs with appropriate management of player exercise load.

Running speed during training and percent body fat predict race time in recreational male marathoners.

PubMed

Barandun, Ursula; Knechtle, Beat; Knechtle, Patrizia; Klipstein, Andreas; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2012-01-01

Recent studies have shown that personal best marathon time is a strong predictor of race time in male ultramarathoners. We aimed to determine variables predictive of marathon race time in recreational male marathoners by using the same characteristics of anthropometry and training as used for ultramarathoners. Anthropometric and training characteristics of 126 recreational male marathoners were bivariately and multivariately related to marathon race times. After multivariate regression, running speed of the training units (β = -0.52, P < 0.0001) and percent body fat (β = 0.27, P < 0.0001) were the two variables most strongly correlated with marathon race times. Marathon race time for recreational male runners may be estimated to some extent by using the following equation (r (2) = 0.44): race time ( minutes) = 326.3 + 2.394 × (percent body fat, %) - 12.06 × (speed in training, km/hours). Running speed during training sessions correlated with prerace percent body fat (r = 0.33, P = 0.0002). The model including anthropometric and training variables explained 44% of the variance of marathon race times, whereas running speed during training sessions alone explained 40%. Thus, training speed was more predictive of marathon performance times than anthropometric characteristics. The present results suggest that low body fat and running speed during training close to race pace (about 11 km/hour) are two key factors for a fast marathon race time in recreational male marathoner runners.

CAN RUNNERS PERCEIVE CHANGES IN HEEL CUSHIONING AS THE SHOE AGES WITH INCREASED MILEAGE?

PubMed Central

Cornwall, Mark W.

2017-01-01

Background For those runners who utilize footwear and have a rearfoot strike pattern, the durability of the midsole heel region has been shown to deteriorate as shoe mileage increases. Purpose The purpose of this study was threefold: 1) to determine if the runner can self-report changes in heel cushioning properties of the midsole after an extended period of distance running, 2) to determine if force and plantar pressures measured in the heel region of the midsole using a capacitance sensor insole change after running 640 km, and 3) to determine if a durometer could be used clinically to objectively measure changes in the hardness of the material in the heel region of the midsole. Study Design Cross-sectional Study Methods Fifteen recreational runners voluntarily consented to participate and were provided with a new pair of running shoes. Each participant's running style was observed and classified as having a rearfoot strike pattern. Inclusion criteria included running at least 24 km per week, experience running on a treadmill, no history of lower extremity congenital or traumatic deformity, or acute injury six months prior to the start of the study. The ability of each participant to self-perceive changes in shoe cushioning, comfort and fit was assessed using the Footwear Comfort Assessment Tool (FCAT). In-shoe plantar pressures and vertical forces were assessed using a capacitance sensor insole while runners ran over a 42-meter indoor runway. A Shore A durometer was used to measure the hardness of the midsole in the heel region. All measures were completed at baseline (zero km) and after running 160, 320, 480, and 640 km. In addition to descriptive statistics, a repeated measures analysis of variance was used to determine if the FCAT, pressures, forces, or midsole hardness changed because of increased running mileage. Result While plantar pressures and vertical forces were significantly reduced in the midsole heel region, none of the runners self-reported a significant reduction in heel cushioning based on FCAT scores after running 640 km. The use of a durometer provided an objective measure of the changes in the heel region of the midsole that closely matched the reductions observed in pressure and force values. Conclusion The results indicated that runners who have a rearfoot strike pattern will have a 16% to 33% reduction in the amount of cushioning in the heel region of the midsole after running 480 km. Although there were significant reductions in heel cushioning, the experienced recreational runners in this study were not able to self-perceive these changes after running 640 km. In addition, the use of a durometer provides a quick and accurate way to assess changes in the hardness of the heel region of the midsole as running mileage increases. Level of Evidence 3, Controlled laboratory study PMID:28900568

The effect of carbohydrate-electrolyte beverage drinking strategy on 10-mile running performance.

PubMed

Rollo, Ian; James, Lewis; Croft, Louise; Williams, Clyde

2012-10-01

The purpose of the current study was to investigate the influence of ingesting a carbohydrate-electrolyte (CHO-E) beverage ad libitum or as a prescribed volume on 10-mile run performance and gastrointestinal (GI) discomfort. Nine male recreational runners completed the 10-mile run under the following 3 conditions: no drinking (ND; 0 ml, 0 g CHO), ad libitum drinking (AD; 315 ± 123 ml, 19 ± 7 g CHO), and prescribed drinking (PD; 1,055 ± 90 ml, 64 ± 5 g CHO). During the AD and PD trials, drinks were provided on completion of Miles 2, 4, 6, and 8. Running performance, speed (km/hr), and 10-mile run time were assessed using a global positioning satellite system. The runners' ratings of perceived exertion and GI comfort were recorded on completion of each lap of the 10-mile run. There was a significant difference (p < .10) in performance times for the 10-mile race for the ND, AD, and PD trials, which were 72:05 ± 3:36, 71:14 ± 3:35, and 72:12 ± 3.53 min:s, respectively (p = .094). Ratings of GI comfort were reduced during the PD trial in comparison with both AD and ND trials. In conclusion, runners unaccustomed to habitually drinking CHO-E beverages during training improved their 10-mile race performance with AD drinking a CHO-E beverage, in comparison with drinking a prescribed volume of the same beverage or no drinking.

Foot strike patterns of runners at the 15-km point during an elite-level half marathon.

PubMed

Hasegawa, Hiroshi; Yamauchi, Takeshi; Kraemer, William J

2007-08-01

There are various recommendations by many coaches regarding foot landing techniques in distance running that are meant to improve running performance and prevent injuries. Several studies have investigated the kinematic and kinetic differences between rearfoot strike (RFS), midfoot strike (MFS), and forefoot strike (FFS) patterns at foot landing and their effects on running efficiency on a treadmill and over ground conditions. However, little is known about the actual condition of the foot strike pattern during an actual road race at the elite level of competition. The purpose of the present study was to document actual foot strike patterns during a half marathon in which elite international level runners, including Olympians, compete. Four hundred fifteen runners were filmed by 2 120-Hz video cameras in the height of 0.15 m placed at the 15.0-km point and obtained sagittal foot landing and taking off images for 283 runners. Rearfoot strike was observed in 74.9% of all analyzed runners, MFS in 23.7%, and FFS in 1.4%. The percentage of MFS was higher in the faster runners group, when all runners were ranked and divided into 50 runner groups at the 15.0-km point of the competition. In the top 50, which included up to the 69th place runner in actual order who passed the 15-km point at 45 minutes, 53 second (this speed represents 5.45 m x s(-1), or 15 minutes, 17 seconds per 5 km), RFS, MFS, and FFS were 62.0, 36.0, and 2.0%, respectively. Contact time (CT) clearly increased for the slower runners, or the placement order increased (r = 0.71, p < or = 0.05). The CT for RFS + FFS for every 50 runners group significantly increased with increase of the placement order. The CT for RFS was significantly longer than MFS + FFS (200.0 +/- 21.3 vs. 183.0 +/- 16 millisecond). Apparent inversion (INV) of the foot at the foot strike was observed in 42% of all runners. The percentage of INV for MFS was higher than for RFS and FFS (62.5, 32.0, and 50%, respectively). The CT with INV for MFS + FFS was significantly shorter than the CT with and without INV for RFS. Furthermore, the CT with INV was significantly shorter than push-off time without INV for RFS. The findings of this study indicate that foot strike patterns are related to running speed. The percentage of RFS increases with the decreasing of the running speed; conversely, the percentage of MFS increases as the running speed increases. A shorter contact time and a higher frequency of inversion at the foot contact might contribute to higher running economy.

Lactate threshold responses to a season of professional British youth soccer

PubMed Central

McMillan, K; Helgerud, J; Grant, S; Newell, J; Wilson, J; Macdonald, R; Hoff, J

2005-01-01

Objective: To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season. Methods: Nine youth soccer players were tested at six different time points throughout the soccer season by sub-maximal blood lactate assessment, using an incremental treadmill protocol. Whole blood lactate concentration and heart frequency (Hf) were determined at each exercise stage. Running velocities at the first lactate inflection point (v-Tlac) and at a blood lactate concentration of 4 mmol l–1 (v-4mM) were determined. Results: Running velocity at the two lactate thresholds increased from the start of pre-season training to the early weeks of the competitive season, from 11.67 (0.29) to 12.96 (0.28) km h–1 for v-Tlac, and from 13.62 (0.25) to 14.67 (0.24) km h–1 for v-4mM (p<0.001). However, v-Tlac and v-4mM when expressed relative to maximum heart frequency (Hfmax) remained unchanged. The Hf to blood lactate concentration relationship was unchanged after the pre-season training period. The two expressions of lactate threshold did not reveal differences between each other. Conclusion: Running velocity at v-Tlac and v-4mM increased significantly over the pre-season period, but v-Tlac and v-4mM were unchanged when expressed relative to Hfmax. This finding may indicate that increased endurance performance may be mainly attributable to alterations in Vo2max. Although lactate assessment of soccer players is useful for determining endurance training adaptations in soccer players, additional assessment of the other two determinants of endurance performance (Vo2max and running economy) may provide more useful information for determining physiological adaptations resulting from soccer training and training interventions. PMID:15976165

Anthropometric and training variables related to half-marathon running performance in recreational female runners.

PubMed

Knechtle, Beat; Knechtle, Patrizia; Barandun, Ursula; Rosemann, Thomas

2011-05-01

The relationship between skin-fold thickness and running has been investigated in distances ranging from 100 m to the marathon distance (42.195 km), with the exclusion of the half-marathon distance (21.0975 km). We investigated the association between anthropometric variables, prerace experience, and training variables with race time in 42 recreational, nonprofessional, female half-marathon runners using bi- and multivariate analysis. Body weight (r, 0.60); body mass index (r, 0.48); body fat percentage (r, 0.56); pectoral (r, 0.61), mid-axilla (r, 0.69), triceps (r, 0.49), subscapular (r, 0.61), abdominal (r, 0.59), suprailiac (r, 0.55), and medial calf (r, 0.53) skin-fold thickness; mean speed of the training sessions (r, -0.68); and personal best time in a half-marathon (r, 0.69) correlated with race time after bivariate analysis. Body weight (P = 0.0054), pectoral skin-fold thickness (P = 0.0068), and mean speed of the training sessions (P = 0.0041) remained significant after multivariate analysis. Mean running speed during training was related to mid-axilla (r, -0.31), subscapular (r, -0.38), abdominal (r, -0.44), and suprailiac (r, -0.41) skin-fold thickness, the sum of 8 skin-fold thicknesses (r, -0.36); and percent body fat (r, -0.31). It was determined that variables of both anthropometry and training were related to half-marathon race time, and that skin-fold thicknesses were associated with running speed during training. For practical applications, high running speed during training (as opposed to extensive training) may both reduce upper-body skin-fold thicknesses and improve race performance in recreational female half-marathon runners.

Peak medial (but not lateral) hamstring activity is significantly lower during stance phase of running. An EMG investigation using a reduced gravity treadmill.

PubMed

Hansen, Clint; Einarson, Einar; Thomson, Athol; Whiteley, Rodney

2017-09-01

The hamstrings are seen to work during late swing phase (presumably to decelerate the extending shank) then during stance phase (presumably stabilizing the knee and contributing to horizontal force production during propulsion) of running. A better understanding of this hamstring activation during running may contribute to injury prevention and performance enhancement (targeting the specific role via specific contraction mode). Twenty active adult males underwent surface EMG recordings of their medial and lateral hamstrings while running on a reduced gravity treadmill. Participants underwent 36 different conditions for combinations of 50%-100% altering bodyweight (10% increments) & 6-16km/h (2km/h increments, i.e.: 36 conditions) for a minimum of 6 strides of each leg (maximum 32). EMG was normalized to the peak value seen for each individual during any stride in any trial to describe relative activation levels during gait. Increasing running speed effected greater increases in EMG for all muscles than did altering bodyweight. Peak EMG for the lateral hamstrings during running trials was similar for both swing and stance phase whereas the medial hamstrings showed an approximate 20% reduction during stance compared to swing phase. It is suggested that the lateral hamstrings work equally hard during swing and stance phase however the medial hamstrings are loaded slightly less every stance phase. Likely this helps explain the higher incidence of lateral hamstring injury. Hamstring injury prevention and rehabilitation programs incorporating running should consider running speed as more potent stimulus for increasing hamstring muscle activation than impact loading. Copyright © 2017 Elsevier B.V. All rights reserved.

Maintaining vigorous activity attenuates 7-yr weight gain in 8340 runners.

PubMed

Williams, Paul T

2007-05-01

Body weight generally increases with aging in Western societies. Although training studies show that exercise produces acute weight loss, it is unclear whether the long-term maintenance of vigorous exercise attenuates the trajectory of age-related weight gain. Specifically, prior studies have not tested whether the maintenance of physical activity, in the absence of any change in activity, prevents weight gain. Prospective study of 6119 male and 2221 female runners whose running distances changed < 5 km x wk(-1) between baseline and follow-up surveys 7 yr later. On average, men who maintained modest (0-23 km x wk(-1)), intermediate (24-47 km x wk(-1)), or prolonged running distances (> or = 48 km x wk(-1)) all gained weight through age 64; however, those who maintained > or = 48 km x wk(-1) had one half the average annual weight gain of those who maintained < 24 km x wk(-1). For example, between the ages of 35 and 44 in men and 30 and 39 yr in women, those who maintained < 24 km x wk(-1) gained, on average, 2.1 and 2.9 kg more per decade than those averaging > 48 km x wk(-1). Age-related weight gain, and its attenuation by maintained exercise, were both greater in younger than in older men. Men's gains in waist circumference with age, and its attenuation by maintaining running, were the same in older and younger men. Regardless of age, women increased their body weight, waist circumference, and hip circumference over time, and these measurements were attenuated in proportion to their maintained running distance. In both sexes, running disproportionately prevented more extreme increases in weight. As they aged, men and women gained less weight in proportion to their levels of sustained vigorous activity. This long-term beneficial effect is in addition to the acute weight loss that occurs with increased activity.

Blood lactate thresholds and walking/running economy are determinants of backpack-running performance in trained soldiers.

PubMed

Simpson, Richard J; Graham, Scott M; Connaboy, Christopher; Clement, Richard; Pollonini, Luca; Florida-James, Geraint D

2017-01-01

We developed a standardized laboratory treadmill protocol for assessing physiological responses to a simulated backpack load-carriage task in trained soldiers, and assessed the efficacy of blood lactate thresholds (LTs) and economy in predicting future backpack running success over an 8-mile course in field conditions. LTs and corresponding physiological responses were determined in 17 elite British soldiers who completed an incremental treadmill walk/run protocol to exhaustion carrying 20 kg backpack load. Treadmill velocity at the breakpoint (r = -0.85) and Δ 1 mmol l(-1) (r = -0.80) LTs, and relative V˙O2 at 4 mmol l(-1) (r = 0.76) and treadmill walk/run velocities of 6.4 (r = 0.76), 7.4 (r = 0.80), 11.4 (r = 0.66) and 12.4 (r = 0.65) km h(-1) were significantly associated with field test completion time. We report for the first time that LTs and backpack walk/run economy are major determinants of backpack load-carriage performance in trained soldiers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Compression Garments, Muscle Contractile Function, and Economy in Trail Runners.

PubMed

Vercruyssen, Fabrice; Gruet, Mathieu; Colson, Serge S; Ehrstrom, Sabine; Brisswalter, Jeanick

2017-01-01

Physiological mechanisms behind the use of compression garments (CGs) during off-road running are unknown. To investigate the influence of wearing CGs vs conventional running clothing (CON) on muscle contractile function and running economy before and after short-distance trail running. Knee-extensor neuromuscular function and running economy assessed from two 5-min treadmill runs (11 and 14 km/h) were evaluated before and after an 18.6-km short-distance trail run in 12 trained athletes wearing either CGs (stocking + short-tight) or CON. Quadriceps neuromuscular function was assessed from mechanical and EMG recording after maximal percutaneous electrical femoral-nerve stimulations (single-twitch doublets at 10 [Db 10 ] and 100 Hz [Db 100 ] delivered at rest and during maximal quadriceps voluntary contraction [MVC]). Running economy (in mL O 2 · km -1 · kg -1 ) increased after trail running independent of the clothing condition and treadmill speeds (P < .001). Similarly, MVC decreased after CON and CGs conditions (-11% and -13%, respectively, P < .001). For both clothing conditions, a significant decrease in quadriceps voluntary activation, Db 10 , Db 100 , and the low-to-high frequency doublet ratio were observed after trail running (time effect, all P < .01), without any changes in rectus femoris maximal M-wave. Wearing CGs does not reduce physiological alterations induced during short-distance trail running. Further studies should determine whether higher intensity of compression pressure during exercises of longer duration may be effective to induce any physiological benefits in experienced trail runners.

Marathon performance in relation to body fat percentage and training indices in recreational male runners

PubMed Central

Tanda, Giovanni; Knechtle, Beat

2013-01-01

Background The purpose of this study was to investigate the effect of anthropometric characteristics and training indices on marathon race times in recreational male marathoners. Methods Training and anthropometric characteristics were collected for a large cohort of recreational male runners (n = 126) participating in the Basel marathon in Switzerland between 2010 and 2011. Results Among the parameters investigated, marathon performance time was found to be affected by mean running speed and the mean weekly distance run during the training period prior to the race and by body fat percentage. The effect of body fat percentage became significant as it exceeded a certain limiting value; for a relatively low body fat percentage, marathon performance time correlated only with training indices. Conclusion Marathon race time may be predicted (r = 0.81) for recreational male runners by the following equation: marathon race time (minutes) = 11.03 + 98.46 exp(−0.0053 mean weekly training distance [km/week]) + 0.387 mean training pace (sec/km) + 0.1 exp(0.23 body fat percentage [%]). The marathon race time results were valid over a range of 165–266 minutes. PMID:24379719

Hyperthermic fatigue precedes a rapid reduction in serum sodium in an ironman triathlete: a case report.

PubMed

Laursen, Paul B; Watson, Greig; Abbiss, Chris R; Wall, Bradley A; Nosaka, Kazunori

2009-12-01

To monitor the hydration, core temperature, and speed (pace) of a triathlete performing an Ironman triathlon. A 35-year-old experienced male triathlete participated in the Western Australian Ironman triathlon on December 1, 2006. The participant was monitored for blood Na(+) concentration before the race (PRE), at the transitions (T1 and T2), halfway through the run (R21), and after the race (POST; 2hPOST). Core body temperature (T(c); pill telemetry) was recorded continuously, and running speed (s3 stride sensor) was measured during the run. The participant completed the race in 11 h 38 min, in hot conditions (26.6 +/- 5.8 degrees C; 42 +/- 19% rel. humidity). His T(c) increased from 37.0 to 38.6 degrees C during the 57-min swim, and averaged 38.4 degrees C during the 335-min bike (33.5 km x h(-1)). After running at 12.4 km x h(-1) for 50 min in the heat (33.1 degrees C), T(c) increased to 39.4 degrees C, before slowing to 10.0 km x h(-1) for 20 min. T(c) decreased to 38.9 degrees C until he experienced severe leg cramps, after which speed diminished to 6 km x h(-1) and T(c) fell to 38.0 degrees C. The athlete's blood Na(+) was constant from PRE to T2 (139-140 mEq x L(-1), but fell to 131 mEq x L(-1) at R21, 133 mEq x L(-1) at POST, and 128 mEq x L(-1) at 2hPOST. The athlete consumed 9.25 L of fluid from PRE to T2, 6.25 L from T2 to POST, and lost 2% of his body mass, indicating sweat losses greater than 15.5 L. This athlete slowed during the run phase following attainment of a critically high T(c) and experienced an unusually rapid reduction in blood Na(+) that preceded cramping, despite presenting with signs of dehydration.

Validity and Reliability of 10-Hz Global Positioning System to Assess In-line Movement and Change of Direction.

PubMed

Nikolaidis, Pantelis T; Clemente, Filipe M; van der Linden, Cornelis M I; Rosemann, Thomas; Knechtle, Beat

2018-01-01

The objectives of the present study were to examine the validity and reliability of the 10 Hz Johan GPS unit in assessing in-line movement and change of direction. The validity was tested against the criterion measure of 200 m track-and-field (track-and-field athletes, n = 8) and 20 m shuttle run endurance test (female soccer players, n = 20). Intra-unit and inter-unit reliability was tested by intra-class correlation coefficient (ICC) and coefficient of variation (CV), respectively. An analysis of variance examined differences between the GPS measurement and five laps of 200 m at 15 km/h, and t -test examined differences between the GPS measurement and 20 m shuttle run endurance test. The difference between the GPS measurement and 200 m distance ranged from -0.13 ± 3.94 m (95% CI -3.42; 3.17) in the first lap to 2.13 ± 2.64 m (95% CI -0.08; 4.33) in the fifth lap. A good intra-unit reliability was observed in 200 m (ICC = 0.833, 95% CI 0.535; 0.962). Inter-unit CV ranged from 1.31% (fifth lap) to 2.20% (third lap). The difference between the GPS measurement and 20 m shuttle run endurance test ranged from 0.33 ± 4.16 m (95% CI -10.01; 10.68) in 11.5 km/h to 9.00 ± 5.30 m (95% CI 6.44; 11.56) in 8.0 km/h. A moderate intra-unit reliability was shown in the second and third stage of the 20 m shuttle run endurance test (ICC = 0.718, 95% CI 0.222;0.898) and good reliability in the fifth, sixth, seventh and eighth (ICC = 0.831, 95% CI -0.229;0.996). Inter-unit CV ranged from 2.08% (11.5 km/h) to 3.92% (8.5 km/h). Based on these findings, it was concluded that the 10 Hz Johan system offers an affordable valid and reliable tool for coaches and fitness trainers to monitor training and performance.

The efficacy of downhill running as a method to enhance running economy in trained distance runners.

PubMed

Shaw, Andrew J; Ingham, Stephen A; Folland, Jonathan P

2018-06-01

Running downhill, in comparison to running on the flat, appears to involve an exaggerated stretch-shortening cycle (SSC) due to greater impact loads and higher vertical velocity on landing, whilst also incurring a lower metabolic cost. Therefore, downhill running could facilitate higher volumes of training at higher speeds whilst performing an exaggerated SSC, potentially inducing favourable adaptations in running mechanics and running economy (RE). This investigation assessed the efficacy of a supplementary 8-week programme of downhill running as a means of enhancing RE in well-trained distance runners. Nineteen athletes completed supplementary downhill (-5% gradient; n = 10) or flat (n = 9) run training twice a week for 8 weeks within their habitual training. Participants trained at a standardised intensity based on the velocity of lactate turnpoint (vLTP), with training volume increased incrementally between weeks. Changes in energy cost of running (E C ) and vLTP were assessed on both flat and downhill gradients, in addition to maximal oxygen uptake (⩒O 2max). No changes in E C were observed during flat running following downhill (1.22 ± 0.09 vs 1.20 ± 0.07 Kcal kg -1  km -1 , P = .41) or flat run training (1.21 ± 0.13 vs 1.19 ± 0.12 Kcal kg -1  km -1 ). Moreover, no changes in E C during downhill running were observed in either condition (P > .23). vLTP increased following both downhill (16.5 ± 0.7 vs 16.9 ± 0.6 km h -1 , P = .05) and flat run training (16.9 ± 0.7 vs 17.2 ± 1.0 km h -1 , P = .05), though no differences in responses were observed between groups (P = .53). Therefore, a short programme of supplementary downhill run training does not appear to enhance RE in already well-trained individuals.

The influence of wearing compression stockings on performance indicators and physiological responses following a prolonged trail running exercise.

PubMed

Vercruyssen, Fabrice; Easthope, Christopher; Bernard, Thierry; Hausswirth, Christophe; Bieuzen, Francois; Gruet, Mathieu; Brisswalter, Jeanick

2014-01-01

The objective of this study was to investigate the effects of wearing compression socks (CS) on performance indicators and physiological responses during prolonged trail running. Eleven trained runners completed a 15.6 km trail run at a competition intensity whilst wearing or not wearing CS. Counter movement jump, maximal voluntary contraction and the oxygenation profile of vastus lateralis muscle using near-infrared spectroscopy (NIRS) method were measured before and following exercise. Run time, heart rate (HR), blood lactate concentration and ratings of perceived exertion were evaluated during the CS and non-CS sessions. No significant difference in any dependent variables was observed during the run sessions. Run times were 5681.1 ± 503.5 and 5696.7 ± 530.7 s for the non-CS and CS conditions, respectively. The relative intensity during CS and non-CS runs corresponded to a range of 90.5-91.5% HRmax. Although NIRS measurements such as muscle oxygen uptake and muscle blood flow significantly increased following exercise (+57.7% and + 42.6%,+59.2% and + 32.4%, respectively for the CS and non-CS sessions, P<0.05), there was no difference between the run conditions. The findings suggest that competitive runners do not gain any practical or physiological benefits from wearing CS during prolonged off-road running.

Rearfoot striking runners are more economical than midfoot strikers.

PubMed

Ogueta-Alday, Ana; Rodríguez-Marroyo, José Antonio; García-López, Juan

2014-03-01

This study aimed to analyze the influence of foot strike pattern on running economy and biomechanical characteristics in subelite runners with a similar performance level. Twenty subelite long-distance runners participated and were divided into two groups according to their foot strike pattern: rearfoot (RF, n = 10) and midfoot (MF, n = 10) strikers. Anthropometric characteristics were measured (height, body mass, body mass index, skinfolds, circumferences, and lengths); physiological (VO2max, anaerobic threshold, and running economy) and biomechanical characteristics (contact and flight times, step rate, and step length) were registered during both incremental and submaximal tests on a treadmill. There were no significant intergroup differences in anthropometrics, VO2max, or anaerobic threshold measures. RF strikers were 5.4%, 9.3%, and 5.0% more economical than MF at submaximal speeds (11, 13, and 15 km·h respectively, although the difference was not significant at 15 km·h, P = 0.07). Step rate and step length were not different between groups, but RF showed longer contact time (P < 0.01) and shorter flight time (P < 0.01) than MF at all running speeds. The present study showed that habitually rearfoot striking runners are more economical than midfoot strikers. Foot strike pattern affected both contact and flight times, which may explain the differences in running economy.

Match running performance and fitness in youth soccer.

PubMed

Buchheit, M; Mendez-Villanueva, A; Simpson, B M; Bourdon, P C

2010-11-01

The activity profiles of highly trained young soccer players were examined in relation to age, playing position and physical capacity. Time-motion analyses (global positioning system) were performed on 77 (U13-U18; fullbacks [FB], centre-backs [CB], midfielders [MD], wide midfielders [W], second strikers [2 (nd)S] and strikers [S]) during 42 international club games. Total distance covered (TD) and very high-intensity activities (VHIA; >16.1 km·h (-1)) were computed during 186 entire player-matches. Physical capacity was assessed via field test measures (e. g., peak running speed during an incremental field test, VVam-eval). Match running performance showed an increasing trend with age ( P<0.001, partial eta-squared (η (2)): 0.20-0.45). When adjusted for age and individual playing time, match running performance was position-dependent ( P<0.001, η (2): 0.13-0.40). MD covered the greater TD; CB the lowest ( P<0.05). Distance for VHIA was lower for CB compared with all other positions ( P<0.05); W and S displayed the highest VHIA ( P<0.05). Relationships between match running performance and physical capacities were position-dependent, with poor or non-significant correlations within FB, CB, MD and W (e. g., VHIA vs. VVam-eval: R=0.06 in FB) but large associations within 2 (nd)S and S positions (e. g., VHIA vs. VVam-eval: R=0.70 in 2 (nd)S). In highly trained young soccer players, the importance of fitness level as a determinant of match running performance should be regarded as a function of playing position.

The Physical Characteristics by Sex and Age for Custody Assistants from a Law Enforcement Agency.

PubMed

Lockie, Robert G; Orr, Robin M; Stierli, Michael; Cesario, Karly A; Moreno, Matthew R; Bloodgood, Ashley M; Dulla, Joseph M; Dawes, J Jay

2018-01-17

Custody assistants (CAs) are a position within a law enforcement agency who are responsible for assisting officers with maintaining security in correctional facilities. Unlike other positions, CAs may not be required to complete physical testing prior to being hired. This lack of testing could influence the characteristics of CAs who attend academy training. Therefore, retrospective analysis of performance test data for 108 officers (69 males, 39 females) was conducted. The tests included: grip strength for both hands; number of push-ups and sit-ups in 60 seconds; 201 m (220 yard) and 2.4 km runs; and maximal aerobic capacity (V˙O2max) estimated from the 2.4 km run. Data were stratified by sex and age (≤24 years, 25-29 years, 30-34 years, ≥35 years). Independent samples t-tests (p < 0.05) calculated differences between males and females. To compare age groups, a one-way ANOVA with Bonferroni post hoc was utilized (p < 0.05). Males scored significantly higher than females in hand grip, push-ups, and sit-ups, were faster over the 201 m and 2.4 km runs, and had a higher V˙O2max (p ≤ 0.001-0.024). There were no significant differences in performance tests across the age groups for either males or females. To better tolerate the rigors of physical training, female CAs should attempt to improve their fitness prior to academy as they often need to complete the same tasks as the males. Age did not appear to influence the physical characteristics of CAs, although all CAs should attempt to develop the fitness qualities needed for their occupation.

The effects of single versus twice daily short term heat acclimation on heat strain and 3000m running performance in hot, humid conditions.

PubMed

Willmott, A G B; Gibson, O R; Hayes, M; Maxwell, N S

2016-02-01

Endurance performances are impaired under conditions of elevated heat stress. Short term heat acclimation (STHA) over 4-6 days can evoke rapid adaptation, which mitigate decrements in performance and alleviate heat strain. This study investigated the efficacy of twice daily heat acclimation (TDHA) compared to single session per day heat acclimation (SDHA) and normothermic training, at inducing heat acclimation phenotype and its impact upon running performance in hot, humid conditions. Twenty one, moderately trained males were matched and assigned to three groups; SDHA (mean±SD) (peak oxygen consumption [V̇O2peak] 45.8±6.1mLkg(-1)min(-1), body mass 81.3±16.0kg, stature 182±3cm), TDHA (46.1±7.0mLkg(-1)min(-1), 80.1±11.9kg, 178±4cm) or control (CON) (47.1±3.5mLkg(-1)min(-1), 78.6±16.7kg, 178±4cm). Interventions consisted of 45min cycling at 50% V̇O2peak, once daily for 4d (SDHA) and twice daily for 2d (TDHA), in 35°C, 60% relative humidity (RH), and once daily for 4 days (CON) in 21°C, 40% RH. Participants completed a pre- and post-intervention 5km treadmill run trial in 30°C, 60% RH, where the first 2km were fixed at 40% V̇O2peak and the final 3km was self-paced. No statistically significant interaction effects occurred within- or between-groups over the 2-4 days intervention. While within-group differences were found in physiological and perceptual measures during the fixed intensity trial post-intervention, they did not statistically differ between-groups. Similarly, TDHA (-36±34s [+3.5%]) and SDHA (-26±28s [+2.8%]) groups improved 3km performances (p=0.35), but did not differ from CON (-6±44s [+0.6%]). This is the first study to investigate the effects of HA twice daily and compare it with traditional single session per day STHA. These STHA protocols may have the ability to induce partial adaptive responses to heat stress and possibly enhance performance in environmentally challenging conditions, however, future development is warranted to optimise the administration to provide a potent stimuli for heat adaptation in athletic and military personnel within a rapid regime. Copyright © 2016 Elsevier Ltd. All rights reserved.

Continuous three dimensional analysis of running mechanics during a marathon by means of inertial magnetic measurement units to objectify changes in running mechanics.

PubMed

Reenalda, Jasper; Maartens, Erik; Homan, Lotte; Buurke, J H Jaap

2016-10-03

Recent developments in wearable and wireless sensor technology allow for a continuous three dimensional analysis of running mechanics in the sport specific setting. The present study is the first to demonstrate the possibility of analyzing three dimensional (3D) running mechanics continuously, by means of inertial magnetic measurement units, to objectify changes in mechanics over the course of a marathon. Three well trained male distance runners ran a marathon while equipped with inertial magnetic measurement units on trunk, pelvis, upper legs, lower legs and feet to obtain a 3D view of running mechanics and to asses changes in running mechanics over the course of a marathon. Data were continuously recorded during the entire 42.2km (26.2Miles) of the Marathon. Data from the individual sensors were transmitted wirelessly to a receiver, mounted on the handlebar of an accompanying cyclist. Anatomical calibration was performed using both static and dynamic procedures and sensor orientations were thus converted to body segment orientations by means of transformation matrices obtained from the segment calibration. Joint angle (hip, knee and ankle) trajectories as well as center of mass (COM) trajectory and acceleration were derived from the sensor data after segment calibration. Data were collected and repeated measures one way ANOVA׳s, with Tukey post-hoc test, were used to statistically analyze differences between the defined kinematic parameters (max hip angle, peak knee flexion at mid-stance and at mid-swing, ankle angle at initial contact and COM vertical displacement and acceleration), averaged over 100 strides, between the first and the last stages (8 and 40km) of the marathon. Significant changes in running mechanics were witnessed between the first and the last stage of the marathon. This study showed the possibility of performing a 3D kinematic analysis of the running technique, in the sport specific setting, by using inertial magnetic measurement units. For the three runners analyzed, significant changes were observed in running mechanics over the course of a marathon. The present measurement technique therefore allows for more in-depth study of running mechanics outside the laboratory setting. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analysis of performance and age of the fastest 100-mile ultra-marathoners worldwide.

PubMed

Rüst, Christoph Alexander; Knechtle, Beat; Rosemann, Thomas; Lepers, Romuald

2013-05-01

The performance and age of peak ultra-endurance performance have been investigated in single races and single race series but not using worldwide participation data. The purpose of this study was to examine the changes in running performance and the age of peak running performance of the best 100-mile ultra-marathoners worldwide. The race times and ages of the annual ten fastest women and men were analyzed among a total of 35,956 finishes (6,862 for women and 29,094 for men) competing between 1998 and 2011 in 100-mile ultra-marathons. The annual top ten performances improved by 13.7% from 1,132±61.8 min in 1998 to 977.6±77.1 min in 2011 for women and by 14.5% from 959.2±36.4 min in 1998 to 820.6±25.7 min in 2011 for men. The mean ages of the annual top ten fastest runners were 39.2±6.2 years for women and 37.2±6.1 years for men. The age of peak running performance was not different between women and men (p>0.05) and showed no changes across the years. These findings indicated that the fastest female and male 100-mile ultra-marathoners improved their race time by ∼14% across the 1998-2011 period at an age when they had to be classified as master athletes. Future studies should analyze longer running distances (>200 km) to investigate whether the age of peak performance increases with increased distance in ultra-marathon running.

Determination of the anaerobic threshold by a noninvasive field test in runners.

PubMed

Conconi, F; Ferrari, M; Ziglio, P G; Droghetti, P; Codeca, L

1982-04-01

The relationship between running speed (RS) and heart rate (HR) was determined in 210 runners. On a 400-m track the athletes ran continuously from an initial velocity of 12-14 km/h to submaximal velocities varying according to the athlete's capability. The HRs were determined through ECG. In all athletes examined, a deflection from the expected linearity of the RS-HR relationship was observed at submaximal RS. The test-retest correlation for the velocities at which this deflection from linearity occurred (Vd) determined in 26 athletes was 0.99. The velocity at the anaerobic threshold (AT), established by means of blood lactate measurements, and Vd were coincident in 10 runners. The correlation between Vd and average running speed (mean RS) in competition was 0.93 in the 5,000 m (mean Vd = 19.13 +/- 1.08 km/h; mean RS = 20.25 +/- 1.15 km/h), 0.95 in the marathon (mean Vd = 18.85 +/- 1.15 km/h; mean RS = 17.40 +/- 1.14 km/h), and 0.99 in the 1-h race (mean Vd = 18.70 +/- 0.98 km/h; mean RS = 18.65 +/- 0.92 km/h), thus showing that AT is critical in determining the running pace in aerobic competitive events.

Association of Physical and Technical Activities With Partial Match Status in a Soccer Professional Team.

PubMed

Moalla, Wassim; Fessi, Mohamed Saieffedin; Makni, Emna; Dellal, Alexandre; Filetti, Cristoforo; Di Salvo, Valter; Chamari, Karim

2018-06-01

Moalla, W, Fessi, MS, Makni, E, Dellal, A, Filetti, C, Di Salvo, V, and Chamari, K. Association of physical and technical activities with partial match status in a soccer professional team. J Strength Cond Res 32(6): 1708-1714, 2018-The purpose of this study was to examine the association between physical and technical activities and partial match status (winning, drawing, or losing) in a professional soccer team over 2 seasons. Physical and technical activities of 52 official matches were collected and analyzed at each 15-minute interval, for each half (45 minutes), and full match (90 minutes) using a multiple-camera computerized tracking system. The results indicated that according to full match outcome: winning status was characterized by players covering more total distance (p ≤ 0.05) and low-intensity running (<14.4 km·h) (p ≤ 0.05), whereas, losing status induced more sprinting (≥25.2 km·h) (p < 0.01) and high-intensity running (≥19.8 km·h) (p ≤ 0.05). However, according to partial match status (i.e., 15 minutes and half time), players covered more distance for all running intensities while winning (p < 0.01). Technical match performance scores were not influenced by match status. In conclusion, the present study showed that the physical activities including high-intensity running and total distance covered were related to the match status, whereas technical activities were not. The overall outcome shows that higher physical activity was associated with winning partial match periods. This approach highlights the importance of physical fitness in soccer and may help coaches to better modulate players' roles and team tactical organization throughout the match.

Running speed during training and percent body fat predict race time in recreational male marathoners

PubMed Central

Barandun, Ursula; Knechtle, Beat; Knechtle, Patrizia; Klipstein, Andreas; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

2012-01-01

Background Recent studies have shown that personal best marathon time is a strong predictor of race time in male ultramarathoners. We aimed to determine variables predictive of marathon race time in recreational male marathoners by using the same characteristics of anthropometry and training as used for ultramarathoners. Methods Anthropometric and training characteristics of 126 recreational male marathoners were bivariately and multivariately related to marathon race times. Results After multivariate regression, running speed of the training units (β = −0.52, P < 0.0001) and percent body fat (β = 0.27, P < 0.0001) were the two variables most strongly correlated with marathon race times. Marathon race time for recreational male runners may be estimated to some extent by using the following equation (r2 = 0.44): race time ( minutes) = 326.3 + 2.394 × (percent body fat, %) − 12.06 × (speed in training, km/hours). Running speed during training sessions correlated with prerace percent body fat (r = 0.33, P = 0.0002). The model including anthropometric and training variables explained 44% of the variance of marathon race times, whereas running speed during training sessions alone explained 40%. Thus, training speed was more predictive of marathon performance times than anthropometric characteristics. Conclusion The present results suggest that low body fat and running speed during training close to race pace (about 11 km/hour) are two key factors for a fast marathon race time in recreational male marathoner runners. PMID:24198587

Sex differences in performance-matched marathon runners.

PubMed

Helgerud, J; Ingjer, F; Strømme, S B

1990-01-01

Six male and six female runners were chosen on the basis of age (20-30 years) and their performance over the marathon distance (mean time = 199.4, SEM 2.3 min for men and 201.8, SEM 1.8 min for women). The purpose was to find possible sex differences in maximal aerobic power (VO2max), anaerobic threshold, running economy, degree and utilization of VO2max (when running a marathon) and amount of training. The results showed that performance-matched male and female marathon runners had approximately the same VO2max (about 60 ml.kg-1.min-1). For both sexes the anaerobic threshold was reached at an exercise intensity of about 83% of VO2max, or 88%-90% of maximal heart rate. The females' running economy was poorer, i.e. their oxygen uptake during running at a standard submaximal speed was higher (P less than 0.05). The heart rate, respiratory exchange ratio and blood lactate concentration also confirmed that a given running speed resulted in higher physiological strain for the females. The percentage utilization of VO2max at the average marathon running speed was somewhat higher for the females, but the difference was not significant. For both sexes the oxygen uptake at average speed was 93%-94% of the oxygen uptake corresponding to the anaerobic threshold. Answers to a questionnaire showed that the females' training programme over the last 2 months prior to running the actual marathon comprised almost twice as many kilometers of running per week compared to the males (60 and 33 km, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Improving Running Economy by Transitioning to Minimalist Footwear: A Randomised Controlled Trial.

PubMed

Lindlein, K; Zech, A; Zoch, A; Braumann, K-M; Hollander, K

2018-05-25

Ongoing debates about benefits and risks of barefoot- and minimally-shod running have, to date, revealed no conclusive findings for long-term effects on physical performance. The purpose of this study was to examine the effects of an 8-week transition to minimalist footwear (MFW) on running economy (RE). Randomised controlled trial. Thirty-two male, habitually-shod runners were assigned randomly to an 8-week training intervention either in minimalist (=intervention group) or conventional running shoes (=control group). The intervention consisted of a gradual increase in use of the new footwear by 5% of the individual weekly distance. Before and after the intervention, a VO 2 max test was followed by a submaximal RE test at 70% and 80% of vVO 2 max in both shoe conditions 7days later. RE was measured at the submaximal tests and expressed as caloric unit cost (kcalkg -1 km -1 ) and oxygen consumption (mlkg -1 km -1 ). RE improved in the intervention group over time compared to the control group with small to moderate effect sizes (ES) in both shoe conditions: Effects on RE (kcalkg -1 km -1 ) in conventional running shoes: ES vVO 2 70%: 0.68 (95% CI: -0.14 to 1.51), ES vVO 2 80%: 0.78 (95% CI: 0-1.56). In minimalist footwear: ES vVO 2 70%: 0.3 (95% CI: -0.54 to 1.14), ES vVO 2 80%: 0.42 (95% CI: -0.41 to 1.25). These effects were not statistically significant (p>0.05). The repeated-measures ANOVA also showed no group by time interactions for all submaximal RE testing conditions (p>0.05). Although not reaching statistical significance, training in MFW compared to CRS resulted in small to moderate improvements in RE. Copyright © 2018 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Disturbance observer based model predictive control for accurate atmospheric entry of spacecraft

NASA Astrophysics Data System (ADS)

Wu, Chao; Yang, Jun; Li, Shihua; Li, Qi; Guo, Lei

2018-05-01

Facing the complex aerodynamic environment of Mars atmosphere, a composite atmospheric entry trajectory tracking strategy is investigated in this paper. External disturbances, initial states uncertainties and aerodynamic parameters uncertainties are the main problems. The composite strategy is designed to solve these problems and improve the accuracy of Mars atmospheric entry. This strategy includes a model predictive control for optimized trajectory tracking performance, as well as a disturbance observer based feedforward compensation for external disturbances and uncertainties attenuation. 500-run Monte Carlo simulations show that the proposed composite control scheme achieves more precise Mars atmospheric entry (3.8 km parachute deployment point distribution error) than the baseline control scheme (8.4 km) and integral control scheme (5.8 km).

Street-running LRT may not affect a neighbour's sleep

NASA Astrophysics Data System (ADS)

Sarkar, S. K.; Wang, J.-N.

2003-10-01

A comprehensive dynamic finite difference model and analysis was conducted simulating LRT running at the speed of 24 km/h on a city street. The analysis predicted ground borne vibration (GBV) to remain at or below the FTA criterion of a RMS velocity of 72 VdB (0.004 in/s) at the nearest residence. In the model, site-specific stratography and dynamic soil and rock properties were used that were determined from in situ testing. The dynamic input load from LRT vehicle running at 24 km/h was computed from actual measured data from Portland, Oregon's West Side LRT project, which used a low floor vehicle similar to the one proposed for the NJ Transit project. During initial trial runs of the LRT system, vibration and noise measurements were taken at three street locations while the vehicles were running at about the 20-24 km/h operating speed. The measurements confirmed the predictions and satisfied FTA criteria for noise and vibration for frequent events. This paper presents the analytical model, GBV predictions, site measurement data and comparison with FTA criterion.

Effects of resistance training on running economy and cross-country performance.

PubMed

Barnes, Kyle R; Hopkins, Will G; McGuigan, Michael R; Northuis, Mark E; Kilding, Andrew E

2013-12-01

Heavy-resistance training and plyometric training offer distinct physiological and neuromuscular adaptations that could enhance running economy and, consequently, distance-running performance. To date, no studies have examined the effect of combining the two modes of training on running economy or performance. Fifty collegiate male and female cross-country runners performed a 5-km time trial and a series of laboratory-based tests to determine aerobic, anthropometric, biomechanical, and neuromuscular characteristics. Thereafter, each athlete participated in a season of six to eight collegiate cross-country races for 13 wk. After the first 4 wk, athletes were randomly assigned to either heavy-resistance or plyometric plus heavy-resistance training. Five days after completing their final competition, runners repeated the same set of laboratory tests. We also estimated the effects of the intervention on competition performance throughout the season using athletes of other teams as controls. Heavy-resistance training produced small-moderate improvements in peak speed, running economy, and neuromuscular characteristics relative to plyometric resistance training, whereas changes in biomechanical measures favored plyometric resistance training. Men made less gains than women in most tests. Both treatments had possibly harmful effects on competition times in men (mean = 0.5%; 90% confidence interval = ±1.2%), but there may have been benefit for some individuals. Both treatments were likely beneficial for all women (-1.2%; ±1.3%), but heavy-resistance training was possibly better than plyometric resistance training. The changes in laboratory-based parameters related to distance-running performance were consistent with the changes in competition times for women but only partly for men. Our data indicate that women should include heavy-resistance training in their programs, but men should be cautious about using it in season until more research establishes whether certain men are positive or negative responders.

The Influence Of Team Rating On Running Performance In Elite Gaelic Football.

PubMed

Mangan, Shane; Malone, Shane; Ryan, Martin; Gahan, Jason Mc; Warne, Joe; Martin, Denise; O'Neill, Cian; Burns, Con; Collins, Kieran

2017-11-06

It is currently unknown how team rating influences running performance in Gaelic football. GPS technologies were used to quantify match-running performance within 5 elite Gaelic football teams over a period of 5 years (2012-2016). In total 780 player data sets were collected over 95 matches. Running performance variables included total distance, high-speed distance (≥17 km h) and the percentage of high-speed distance. Team ratings were determined objectively using the Elo Ratings System for Gaelic football. Reference team rating had trivial effects on total distance (p = 0.011, partial η2 = 0.008) and high-speed distance (p = 0.011, partial η2 = 0.008). Opposition team rating had small effects on total distance (p = 0.005, partial η2 = 0.016) and high-speed distance (p = 0.001, partial η2 = 0.020). Top tier teams cover greater total distances and high-speed distance than lower tier teams. Players cover considerably less total distance and high-speed distance against tier 3 and tier 4 teams. Tier 1 players ran a significantly higher percentage of distance at high-speed, than players who played for tier 2 teams (p = 0.020). The competitive advantage of top tier Gaelic football teams is closely linked with their ability to demonstrate a higher physical intensity than lower tier teams.

Comparison of Minimalist Footwear Strategies for Simulating Barefoot Running: A Randomized Crossover Study

PubMed Central

Hollander, Karsten; Argubi-Wollesen, Andreas; Reer, Rüdiger; Zech, Astrid

2015-01-01

Possible benefits of barefoot running have been widely discussed in recent years. Uncertainty exists about which footwear strategy adequately simulates barefoot running kinematics. The objective of this study was to investigate the effects of athletic footwear with different minimalist strategies on running kinematics. Thirty-five distance runners (22 males, 13 females, 27.9 ± 6.2 years, 179.2 ± 8.4 cm, 73.4 ± 12.1 kg, 24.9 ± 10.9 km.week-1) performed a treadmill protocol at three running velocities (2.22, 2.78 and 3.33 m.s-1) using four footwear conditions: barefoot, uncushioned minimalist shoes, cushioned minimalist shoes, and standard running shoes. 3D kinematic analysis was performed to determine ankle and knee angles at initial foot-ground contact, rate of rear-foot strikes, stride frequency and step length. Ankle angle at foot strike, step length and stride frequency were significantly influenced by footwear conditions (p<0.001) at all running velocities. Posthoc pairwise comparisons showed significant differences (p<0.001) between running barefoot and all shod situations as well as between the uncushioned minimalistic shoe and both cushioned shoe conditions. The rate of rear-foot strikes was lowest during barefoot running (58.6% at 3.33 m.s-1), followed by running with uncushioned minimalist shoes (62.9%), cushioned minimalist (88.6%) and standard shoes (94.3%). Aside from showing the influence of shod conditions on running kinematics, this study helps to elucidate differences between footwear marked as minimalist shoes and their ability to mimic barefoot running adequately. These findings have implications on the use of footwear applied in future research debating the topic of barefoot or minimalist shoe running. PMID:26011042

Comparison of minimalist footwear strategies for simulating barefoot running: a randomized crossover study.

PubMed

Hollander, Karsten; Argubi-Wollesen, Andreas; Reer, Rüdiger; Zech, Astrid

2015-01-01

Possible benefits of barefoot running have been widely discussed in recent years. Uncertainty exists about which footwear strategy adequately simulates barefoot running kinematics. The objective of this study was to investigate the effects of athletic footwear with different minimalist strategies on running kinematics. Thirty-five distance runners (22 males, 13 females, 27.9 ± 6.2 years, 179.2 ± 8.4 cm, 73.4 ± 12.1 kg, 24.9 ± 10.9 km x week(-1)) performed a treadmill protocol at three running velocities (2.22, 2.78 and 3.33 m x s(-1)) using four footwear conditions: barefoot, uncushioned minimalist shoes, cushioned minimalist shoes, and standard running shoes. 3D kinematic analysis was performed to determine ankle and knee angles at initial foot-ground contact, rate of rear-foot strikes, stride frequency and step length. Ankle angle at foot strike, step length and stride frequency were significantly influenced by footwear conditions (p<0.001) at all running velocities. Posthoc pairwise comparisons showed significant differences (p<0.001) between running barefoot and all shod situations as well as between the uncushioned minimalistic shoe and both cushioned shoe conditions. The rate of rear-foot strikes was lowest during barefoot running (58.6% at 3.33 m x s(-1)), followed by running with uncushioned minimalist shoes (62.9%), cushioned minimalist (88.6%) and standard shoes (94.3%). Aside from showing the influence of shod conditions on running kinematics, this study helps to elucidate differences between footwear marked as minimalist shoes and their ability to mimic barefoot running adequately. These findings have implications on the use of footwear applied in future research debating the topic of barefoot or minimalist shoe running.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Qian; Fan, Jiwen; Hagos, Samson M.

Understanding of critical processes that contribute to the organization of mesoscale convective systems is important for accurate weather forecast and climate prediction. In this study, we investigate the effects of wind shear at different vertical levels on the organization and properties of cloud systems using the Weather Research & Forecasting (WRF) model with a spectral-bin microphysical scheme. The sensitivity experiments are performed by increasing wind shear at the lower (0-5 km), middle (5-10 km), upper (> 10 km) and the entire troposphere, respectively, based on a control run for a mesoscale convective system (MCS) with weak wind shear. We findmore » that increasing wind shear at the both lower and middle vertical levels reduces the domain-accumulated precipitation and the occurrence of heavy rain, while increasing wind shear at the upper levels changes little on precipitation. Although increasing wind shear at the lower-levels is favorable for a more organized quasi-line system which leads to enlarged updraft core area, and enhanced updraft velocities and vertical mass fluxes, the precipitation is still reduced by 18.6% compared with the control run due to stronger rain evaporation induced by the low-level wind shear. Strong wind shear in the middle levels only produces a strong super-cell over a narrow area, leading to 67.3% reduction of precipitation over the domain. By increasing wind shear at the upper levels only, the organization of the convection is not changed much, but the increased cloudiness at the upper-levels leads to stronger surface cooling and then stabilizes the atmosphere and weakens the convection. When strong wind shear exists over the entire vertical profile, a deep dry layer (2-9 km) is produced and convection is severely suppressed. There are fewer very-high (cloud top height (CTH) > 15 km) and very-deep (cloud thickness > 15 km) clouds, and the precipitation is only about 11.8% of the control run. The changes in cloud microphysical properties further explain the reduction of surface rain by strong wind shear especially at the lower- and middle-levels. The insights obtained from this study help us better understand the cloud system organization and provide foundation for better parameterizing organized MCS.« less

High intensity interval training vs. high-volume running training during pre-season conditioning in high-level youth football: a cross-over trial.

PubMed

Faude, Oliver; Schnittker, Reinhard; Schulte-Zurhausen, Roman; Müller, Florian; Meyer, Tim

2013-01-01

We aimed at comparing the endurance effects of high-intensity interval training (HIIT) with high-volume running training (HVT) during pre-season conditioning in 20 high-level youth football players (15.9 (s 0.8) years). Players either conducted HVT or HIIT during the summer preparation period. During winter preparation they performed the other training programme. Before and after each training period several fitness tests were conducted: multi-stage running test (to assess the individual anaerobic threshold (IAT) and maximal running velocity (Vmax)), vertical jumping height, and straight sprinting. A significant increase from pre- to post-test was observed in IAT velocity (P < 0.001) with a greater increase after HVT (+0.8 km · h(-1) vs. +0.5 km · h(-1) after HIIT, P = 0.04). Maximal velocity during the incremental exercise test also slightly increased with time (P = 0.09). Forty per cent (HIIT) and 15% (HVT) of all players did not improve IAT beyond baseline variability. The players who did not respond to HIIT were significantly slower during 30 m sprinting than responders (P = 0.02). No further significant differences between responders and non-responders were observed. Jump heights deteriorated significantly after both training periods (P < 0.003). Both training programmes seem to be promising means to improve endurance capacity in high-level youth football players during pre-season conditioning.

Similarities and differences among half-marathon runners according to their performance level

PubMed Central

Morante, Juan Carlos; Gómez-Molina, Josué; García-López, Juan

2018-01-01

This study aimed to identify the similarities and differences among half-marathon runners in relation to their performance level. Forty-eight male runners were classified into 4 groups according to their performance level in a half-marathon (min): Group 1 (n = 11, < 70 min), Group 2 (n = 13, < 80 min), Group 3 (n = 13, < 90 min), Group 4 (n = 11, < 105 min). In two separate sessions, training-related, anthropometric, physiological, foot strike pattern and spatio-temporal variables were recorded. Significant differences (p<0.05) between groups (ES = 0.55–3.16) and correlations with performance were obtained (r = 0.34–0.92) in training-related (experience and running distance per week), anthropometric (mass, body mass index and sum of 6 skinfolds), physiological (VO2max, RCT and running economy), foot strike pattern and spatio-temporal variables (contact time, step rate and length). At standardized submaximal speeds (11, 13 and 15 km·h-1), no significant differences between groups were observed in step rate and length, neither in contact time when foot strike pattern was taken into account. In conclusion, apart from training-related, anthropometric and physiological variables, foot strike pattern and step length were the only biomechanical variables sensitive to half-marathon performance, which are essential to achieve high running speeds. However, when foot strike pattern and running speeds were controlled (submaximal test), the spatio-temporal variables were similar. This indicates that foot strike pattern and running speed are responsible for spatio-temporal differences among runners of different performance level. PMID:29364940

Increase of Total Body Water with Decrease of Body Mass while Running 100 km Nonstop--Formation of Edema?

ERIC Educational Resources Information Center

Knechtle, Beat; Wirth, Andrea; Knechtle, Patrizia; Rosemann, Thomas

2009-01-01

We investigated whether ultraendurance runners in a 100-km run suffer a decrease of body mass and whether this loss consists of fat mass, skeletal muscle mass, or total body water. Male ultrarunners were measured pre- and postrace to determine body mass, fat mass, and skeletal muscle mass by using the anthropometric method. In addition,…

Analysis of performance and age of the fastest 100-mile ultra-marathoners worldwide

PubMed Central

Rüst, Christoph Alexander; Knechtle, Beat; Rosemann, Thomas; Lepers, Romuald

2013-01-01

OBJECTIVES: The performance and age of peak ultra-endurance performance have been investigated in single races and single race series but not using worldwide participation data. The purpose of this study was to examine the changes in running performance and the age of peak running performance of the best 100-mile ultra-marathoners worldwide. METHOD: The race times and ages of the annual ten fastest women and men were analyzed among a total of 35,956 finishes (6,862 for women and 29,094 for men) competing between 1998 and 2011 in 100-mile ultra-marathons. RESULTS: The annual top ten performances improved by 13.7% from 1,132±61.8 min in 1998 to 977.6±77.1 min in 2011 for women and by 14.5% from 959.2±36.4 min in 1998 to 820.6±25.7 min in 2011 for men. The mean ages of the annual top ten fastest runners were 39.2±6.2 years for women and 37.2±6.1 years for men. The age of peak running performance was not different between women and men (p>0.05) and showed no changes across the years. CONCLUSION: These findings indicated that the fastest female and male 100-mile ultra-marathoners improved their race time by ∼14% across the 1998–2011 period at an age when they had to be classified as master athletes. Future studies should analyze longer running distances (>200 km) to investigate whether the age of peak performance increases with increased distance in ultra-marathon running. PMID:23778421

Elite football on artificial turf versus natural grass: movement patterns, technical standards, and player impressions.

PubMed

Andersson, Helena; Ekblom, Björn; Krustrup, Peter

2008-01-15

The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.

Comparison of training and anthropometric characteristics between recreational male half-marathoners and marathoners.

PubMed

Zillmann, Teresa; Knechtle, Beat; Rüst, Christoph Alexander; Knechtle, Patrizia; Rosemann, Thomas; Lepers, Romuald

2013-06-30

Participation in endurance running such as half-marathon (21-km) and marathon (42-km) has increased over the last decades. We compared 147 recreational male half-marathoners and 126 recreational male marathoners to investigate similarities or differences in their anthropometric and training characteristics. The half-marathoners were heavier (P < 0.05), had longer legs (P < 0.001), thicker upper arms (P < 0.05), a thicker thigh (P < 0.01), a higher sum of skinfold thicknesses (P < 0.01), a higher body fat percentage (P < 0.05) and a higher skeletal muscle mass (P < 0.05) than the marathoners. They had fewer years of experience (P < 0.05), completed fewer weekly training kilometers (P < 0.001), and fewer weekly running hours (P < 0.01) compared to the marathoners. For half-marathoners, body mass index (P = 0.011), percent body fat (P = 0.036) and speed in running during training (P < 0.0001) were related to race time (r2 = 0.47). For marathoners, percent body fat (P = 0.001) and speed in running during training (P < 0.0001) were associated to race time (r2 = 0.47). When body mass index was excluded for the half-marathoners in the multi-variate analysis, r2 decreased to 0.45, therefore body mass index explained only 2% of the variance of half-marathon performance. Percent body fat was significantly and negatively related to running speed during training in both groups. To summarize, half-marathoners showed differences in both anthropometry and training characteristics compared to marathoners that could be related to their lower training volume, most probably due to the shorter race distance they intended to compete. Both groups of athletes seemed to profit from low body fat and a high running speed during training for fast race times.

Ultraendurance triathlon participation: typical race preparation of lower level triathletes.

PubMed

Gulbin, J P; Gaffney, P T

1999-03-01

This study sought to describe the training preparations and performances of lower level ultraendurance triatheletes. The lower level or typical ultraendurance athlete was defined as any participant eligible to compete, irrespective of ability. participants completed a retrospective questionnaire related to their athletic background, triathlon experience and performances, and training preparation. all competitors in the 1995 Lanzarote Ironman (i.m.) triathlon had the opportunity to complete the questionnaire in the days prior to the race. 242 (230 m, 12 f) or 45% of the entire race field completed the questionnaire. measures of central tendency were used to describe all data. Forward step-wise multiple regression techniques were used to predict performance from training variables. Statistical significance was accepted at p < 0.05. Mean finish time for all study participants was 11.76 hours. Subjects were 34.2 +/- 8.8 years, 1.77 +/- 0.07 m, and 70.8 +/- 7.1 kg. They had 6.0 +/- 3.2 years experience in triathlon, had completed 3.0 +/- 4.1 IM races, and spent 21.5 +/- 10.8 weeks preparing for the IM. Training distances/week for swimming, cycling and running, were 8.8 +/- 4.3 km, 270 +/- 107 km, and 58.2 +/- 21.9 km, at a pace of 18.1 min/km, 31.8 km/hr, and 4.55 min/km respectively. Previous best performances in Olympic distance triathlon (1.5/40/10) coupled with weekly cycling distances and longest training ride, could partially predict overall performance (R2 = 0.57). Finishing an IM requires less training than has been previously reported in studies that have primarily focused on elite competitors. Additionally, training distances appear to be a more important factor for competitive success than training paces.

Ecological validity of the Yo-Yo SFIE2 test.

PubMed

Krustrup, P; Randers, M; Horton, J; Brito, J; Rebelo, A

2012-06-01

The present study investigated the movement pattern of Portuguese top-level futsal referees (n=16) during competitive games and the ecological validity of the new Yo-Yo Sideways-Forwards Intermittent Endurance level 2 test (Yo-Yo SFIE2). Total distance covered (TD), high-intensity running (HIR), sprinting (SPR), and sideways running (Sw) during matches were 5.78±0.24 (±SEM), 0.77±0.08, 0.17±0.02 and 1.61±0.28 km, respectively, with peak 5-min values of 0.50±0.02, 0.12±0.01, 0.05±0.01 and 0.20±0.02 km, respectively. TD, HIR and Sw decreased by 30% (p<0.001), 43% and 60% (p<0.01), respectively from the first to the last 10-min period. Yo-Yo SFIE2 performance was 1205±107 (625-2015) m and showed large correlations with match-values and peak 5-min values for HIR (r=0.58 and 0.68, p<0.01) and SPR (r=0.56 and 0.57, p<0.05). Yo-Yo SFIE2 HR after 4 min [95±1 (87-99) % HRpeak] showed a nearly perfect inverse correlation with Yo-Yo SFIE2 performance (r= -0.90, p<0.001) and large inverse correlations (p<0.05) with match-values and peak 5-min values for HIR (r= -0.55 and -0.71) and SPR (r= -0.57 and -0.55). In conclusion, the Yo-Yo SFIE2 test is movement-specific for top-level futsal referees as high-intensity running and sideways running are important parts of their match activity profile, and maximal and sub-maximal versions of the Yo-Yo SFIE2 test correlates with certain aspects of the physical match performance of top-level futsal referees. © Georg Thieme Verlag KG Stuttgart · New York.

Numerical simulations of Hurricane Katrina (2005) in the turbulent gray zone

NASA Astrophysics Data System (ADS)

Green, Benjamin W.; Zhang, Fuqing

2015-03-01

Current numerical simulations of tropical cyclones (TCs) use a horizontal grid spacing as small as Δx = 103 m, with all boundary layer (BL) turbulence parameterized. Eventually, TC simulations can be conducted at Large Eddy Simulation (LES) resolution, which requires Δx to fall in the inertial subrange (often <102 m) to adequately resolve the large, energy-containing eddies. Between the two lies the so-called "terra incognita" because some of the assumptions used by mesoscale models and LES to treat BL turbulence are invalid. This study performs several 4-6 h simulations of Hurricane Katrina (2005) without a BL parameterization at extremely fine Δx [333, 200, and 111 m, hereafter "Large Eddy Permitting (LEP) runs"] and compares with mesoscale simulations with BL parameterizations (Δx = 3 km, 1 km, and 333 m, hereafter "PBL runs"). There are profound differences in the hurricane BL structure between the PBL and LEP runs: the former have a deeper inflow layer and secondary eyewall formation, whereas the latter have a shallow inflow layer without a secondary eyewall. Among the LEP runs, decreased Δx yields weaker subgrid-scale vertical momentum fluxes, but the sum of subgrid-scale and "grid-scale" fluxes remain similar. There is also evidence that the size of the prevalent BL eddies depends upon Δx, suggesting that convergence to true LES has not yet been reached. Nevertheless, the similarities in the storm-scale BL structure among the LEP runs indicate that the net effect of the BL on the rest of the hurricane may be somewhat independent of Δx.

The acute effects of graded physiological strain on soccer kicking performance: a randomized, controlled cross-over study.

PubMed

Radman, Ivan; Wessner, Barbara; Bachl, Norbert; Ruzic, Lana; Hackl, Markus; Prpic, Tomislav; Markovic, Goran

2016-02-01

The aim of the present study was to examine the acute effects of graded physiological strain on soccer kicking performance. Twenty-eight semi-professional soccer players completed both experimental and control procedure. The experimental protocol incorporated repeated shooting trials combined with a progressive discontinuous maximal shuttle-run intervention. The initial running velocity was 8 km/h and increasing for 1 km/h every 3 min until exhaustion. The control protocol comprised only eight subsequent shooting trials. The soccer-specific kicking accuracy (KA; average distance from the ball-entry point to the goal center), kicking velocity (KV), and kicking quality (KQ; kicking accuracy divided by the time elapsed from hitting the ball to the point of entry) were evaluated via reproducible and valid test over five individually determined exercise intensity zones. Compared with baseline or exercise at intensities below the second lactate threshold (LT2), physiological exertion above the LT2 (blood lactate > 4 mmol/L) resulted in meaningful decrease in KA (11-13%; p < 0.05), KV (3-4%; p < 0.05), and overall KQ (13-15%; p < 0.01). The light and moderate-intensity exercise below the LT2 had no significant effect on soccer kicking performance. The results suggest that high-intensity physiological exertion above the player's LT2 impairs soccer kicking performance. In contrast, light to moderate physiological stress appears to be neither harmful nor beneficial for kicking performance.

Running biomechanics: shorter heels, better economy.

PubMed

Scholz, M N; Bobbert, M F; van Soest, A J; Clark, J R; van Heerden, J

2008-10-01

Better running economy (i.e. a lower rate of energy consumption at a given speed) is correlated with superior distance running performance. There is substantial variation in running economy, even among elite runners. This variation might be due to variation in the storage and reutilization of elastic energy in tendons. Using a simple musculoskeletal model, it was predicted that the amount of energy stored in a tendon during a given movement depends more critically on moment arm than on mechanical properties of the tendon, with the amount of stored energy increasing as the moment arm gets smaller. Assuming a link between elastic energy reutilization and overall metabolic cost of running, a smaller moment arm should therefore be associated with superior running economy. This prediction was confirmed experimentally in a group of 15 highly trained runners. The moment arm of the Achilles tendon was determined from standardized photographs of the ankle, using the position of anatomical landmarks. Running economy was measured as the rate of metabolic energy consumption during level treadmill running at a speed of 16 km h(-1). A strong correlation was found between the moment arm of the Achilles tendon and running economy. Smaller muscle moment arms correlated with lower rates of metabolic energy consumption (r(2)=0.75, P<0.001).

Effects of prolonged strenuous endurance exercise on plasma myosin heavy chain fragments and other muscular proteins. Cycling vs running.

PubMed

Koller, A; Mair, J; Schobersberger, W; Wohlfarter, T; Haid, C; Mayr, M; Villiger, B; Frey, W; Puschendorf, B

1998-03-01

This study evaluates creatine kinase, myosin heavy chain, and cardiac troponin blood levels following three types of exercise: 1) short-distance uphill or downhill running; 2) alpine ultramarathon; and 3) alpine long-distance cycling. Comparative field study; follow-up up to 10 days. Department of Sports Medicine. All biochemical markers were analysed at the Department of Medical Chemistry and Biochemistry. Subjects included healthy, trained males (N = 53). All subjects were nonsmokers and free from medication prior to and during the study. Each volunteer was an experienced runner or cyclist, who had at least once successfully finished the Swiss Alpine Marathon of Davos or the Otztal-Radmarathon before. Running or cycling. Plasma concentrations of creatine kinase, myosin heavy chain fragments and cardiac troponins were measured to diagnose skeletal and cardiac muscle damage, respectively. Skeletal muscle protein release is markedly different between uphill and downhill running, with very little evidence for muscle damage in the uphill runners. There is considerable muscle protein leakage in the ultramarathoners (67 km distance; 30 km downhill running). In contrast, only modest amounts of skeletal muscle damage are found after alpine long-distance cycling (230 km distance). This study proves that there is slow-twitch skeletal muscle fiber damage after prolonged strenuous endurance exercise and short-distance downhill running. Exhaustive endurance exercise involving downhill running and short-distance downhill running lead to more pronounced injury than strenuous endurance exercise involving concentric actions. From our results there is no reason for suggesting that prolonged intense exercise may induce myocardial injury in symptom-less athletes without cardiac deseases.

First Assessment of Itaipu Dam Ensemble Inflow Forecasting System

NASA Astrophysics Data System (ADS)

Mainardi Fan, Fernando; Machado Vieira Lisboa, Auder; Gomes Villa Trinidad, Giovanni; Rógenes Monteiro Pontes, Paulo; Collischonn, Walter; Tucci, Carlos; Costa Buarque, Diogo

2017-04-01

Inflow forecasting for Hydropower Plants (HPP) Dams is one of the prominent uses for hydrological forecasts. A very important HPP in terms of energy generation for South America is the Itaipu Dam, located in the Paraná River, between Brazil and Paraguay countries, with a drainage area of 820.000km2. In this work, we present the development of an ensemble forecasting system for Itaipu, operational since November 2015. The system is based in the MGB-IPH hydrological model, includes hydrodynamics simulations of the main river, and is run every day morning forced by seven different rainfall forecasts: (i) CPTEC-ETA 15km; (ii) CPTEC-BRAMS 5km; (iii) SIMEPAR WRF Ferrier; (iv) SIMEPAR WRF Lin; (v) SIMEPAR WRF Morrison; (vi) SIMEPAR WRF WDM6; (vii) SIMEPAR MEDIAN. The last one (vii) corresponds to the median value of SIMEPAR WRF model versions (iii to vi) rainfall forecasts. Besides the developed system, the "traditional" method for inflow forecasting generation for the Itaipu Dam is also run every day. This traditional method consists in the approximation of the future inflow based on the discharge tendency of upstream telemetric gauges. Nowadays, after all the forecasts are run, the hydrology team of Itaipu develop a consensus forecast, based on all obtained results, which is the one used for the Itaipu HPP Dam operation. After one year of operation a first evaluation of the Ensemble Forecasting System was conducted. Results show that the system performs satisfactory for rising flows up to five days lead time. However, some false alarms were also issued by most ensemble members in some cases. And not in all cases the system performed better than the traditional method, especially during hydrograph recessions. In terms of meteorological forecasts, some members usage are being discontinued. In terms of the hydrodynamics representation, it seems that a better information of rivers cross section could improve hydrographs recession curves forecasts. Those opportunities for improvements are currently being addressed in the system next update.

The present status of the high temperature superconducting Maglev vehicle in China

NASA Astrophysics Data System (ADS)

Wang, J. S.; Wang, S. Y.; Zeng, Y. W.; Deng, C. Y.; Ren, Z. Y.; Wang, X. R.; Song, H. H.; Wang, X. Z.; Zheng, J.; Zhao, Y.

2005-02-01

Since the first successful running of the people-carrying high temperature superconducting (HTS) Maglev test vehicle on 31 December 2000, about 27 000 people have taken it, and the accumulated running distance is about 400 km. The levitation force of the onboard HTS equipment is measured periodically, and new experimental results measured on 5 March 2003 show that the performance of the onboard HTS Maglev equipment is almost the same as that of two years ago. Experimental results indicate that the long-term stability of the HTS Maglev vehicle is good. This further proves the feasibility of the HTS Maglev vehicle for practical transportation. It is worth mentioning that all the results are measured at a low speed; however, investigations of the dynamic performance of the HTS Maglev vehicle at high speed are necessary for practical application. Research on the dynamic performance of the HTS Maglev vehicle is ongoing.

Daily hydro- and morphodynamic simulations at Duck, NC, USA using Delft3D

NASA Astrophysics Data System (ADS)

Penko, Allison; Veeramony, Jay; Palmsten, Margaret; Bak, Spicer; Brodie, Katherine; Hesser, Tyler

2017-04-01

Operational forecasting of the coastal nearshore has wide ranging societal and humanitarian benefits, specifically for the prediction of natural hazards due to extreme storm events. However, understanding the model limitations and uncertainty is as equally important as the predictions themselves. By comparing and contrasting the predictions of multiple high-resolution models in a location with near real-time collection of observations, we are able to perform a vigorous analysis of the model results in order to achieve more robust and certain predictions. In collaboration with the U.S. Army Corps of Engineers Field Research Facility (USACE FRF) as part of the Coastal Model Test Bed (CMTB) project, we have set up Delft3D at Duck, NC, USA to run in near-real time, driven by measured wave data at the boundary. The CMTB at the USACE FRF allows for the unique integration of operational wave, circulation, and morphology models with real-time observations. The FRF has an extensive array of in-situ and remotely sensed oceanographic, bathymetric, and meteorological data that is broadcast in near-real time onto a publically accessible server. Wave, current, and bed elevation instruments are permanently installed across the model domain including 2 waverider buoys in 17-m and 26-m water depths at 3.5-km and 17-km offshore, respectively, that record directional wave data every 30-min. Here, we present the workflow and output of the Delft3D hydro- and morphodynamic simulations at Duck, and show the tactical benefits and operational potential of such a system. A nested Delft3D simulation runs a parent grid that extends 12-km in the along-shore and 3.5-km in the cross-shore with 50-m resolution and a maximum depth of approximately 17-m. The bathymetry for the parent grid was obtained from a regional digital elevation model (DEM) generated by the Federal Emergency Management Agency (FEMA). The inner nested grid extends 1.8-km in the along-shore and 1-km in the cross-shore with 5-m resolution and a maximum depth of approximately 8-m. The inner nested grid initial model bathymetry is set to either the predicted bathymetry from the previous day's simulation or a survey, whichever is more recent. Delft3D-WAVE runs in the parent grid and is driven with the real-time spectral wave measurements from the waverider buoy in 17-m depth. The spectral output from Delft3D-WAVE in the parent grid is then used as the boundary condition for the inner nested high-resolution grid, in which the coupled Delft3D wave-flow-morphology model is run. The model results are then compared to the wave, current, and bathymetry observations collected at the FRF as well as other models that are run in the CMTB.

Aerobic fitness and performance in elite female futsal players

PubMed Central

Subiela, JV; Granda-Vera, J; Castagna, C; Gómez, M; Del Coso, J

2015-01-01

Despite its growing popularity, few studies have investigated specific physiological demands for elite female futsal. The aim of this study was to determine aerobic fitness in elite female futsal players using laboratory and field testing. Fourteen female futsal players from the Venezuelan National team (age =21.2±4.0 years; body mass =58.6±5.6 kg; height =161±5.0 cm) performed a progressive maximal treadmill test under laboratory conditions. Players also performed a progressive intermittent futsal-specific field test for endurance, the Futsal Intermittent Endurance Test (FIET), until volitional fatigue. Outcome variables were exercise heart rate (HR), VO2, post-exercise blood lactate concentrations ([La]b) and running speeds (km · h-1). During the treadmill test, VO2max, maximal aerobic speed (MAS), HR and peak [La]b were 45.3±5.6 ml · kg-1 · min-1, 12.5±1.77 km · h-1, 197±8 beats · min-1 and 11.3±1.4 mmol · l-1, respectively. The FIET total distance, peak running velocity, peak HR and [La]b were 1125.0±121.0 m, 15.2±0.5 km · h-1, 199±8 beats · min-1 and 12.5±2.2 mmol · l-1, respectively. The FIET distance and peak speed were strongly associated (r= 0.85-87, p < 0.0001) with VO2max and MAS, respectively. Peak HR and [La]b were not significantly different between tests. Elite female futsal players possess moderate aerobic fitness. Furthermore, the FIET can be considered as a valid field test to determine aerobic fitness in elite level female futsal players. PMID:28479664

Aerobic fitness and performance in elite female futsal players.

PubMed

Barbero-Alvarez, J C; Subiela, J V; Granda-Vera, J; Castagna, C; Gómez, M; Del Coso, J

2015-12-01

Despite its growing popularity, few studies have investigated specific physiological demands for elite female futsal. The aim of this study was to determine aerobic fitness in elite female futsal players using laboratory and field testing. Fourteen female futsal players from the Venezuelan National team (age =21.2±4.0 years; body mass =58.6±5.6 kg; height =161±5.0 cm) performed a progressive maximal treadmill test under laboratory conditions. Players also performed a progressive intermittent futsal-specific field test for endurance, the Futsal Intermittent Endurance Test (FIET), until volitional fatigue. Outcome variables were exercise heart rate (HR), VO 2 , post-exercise blood lactate concentrations ([La]b) and running speeds (km · h -1 ). During the treadmill test, VO 2 max, maximal aerobic speed (MAS), HR and peak [La]b were 45.3±5.6 ml · kg -1 · min -1 , 12.5±1.77 km · h -1 , 197±8 beats · min -1 and 11.3±1.4 mmol · l -1 , respectively. The FIET total distance, peak running velocity, peak HR and [La]b were 1125.0±121.0 m, 15.2±0.5 km · h -1 , 199±8 beats · min -1 and 12.5±2.2 mmol · l -1 , respectively. The FIET distance and peak speed were strongly associated (r= 0.85-87, p < 0.0001) with VO 2 max and MAS, respectively. Peak HR and [La]b were not significantly different between tests. Elite female futsal players possess moderate aerobic fitness. Furthermore, the FIET can be considered as a valid field test to determine aerobic fitness in elite level female futsal players.

Physical and Physiological Demands of Experienced Male Basketball Players During a Competitive Game.

PubMed

Puente, Carlos; Abián-Vicén, Javier; Areces, Francisco; López, Roberto; Del Coso, Juan

2017-04-01

Puente, C, Abián-Vicén, J, Areces, F, López, R, and Del Coso, J. Physical and physiological demands of experienced male basketball players during a competitive game. J Strength Cond Res 31(4): 956-962, 2017-The aim of this investigation was to analyze the physical and physiological demands of experienced basketball players during a real and competitive game. Twenty-five well-trained basketball players (8 guards, 8 forwards, and 9 centers) played a competitive game on an outdoor court. Instantaneous running speeds, the number of body impacts above 5 g, and the number of accelerations and decelerations were assessed by means of a 15-Hz global Positioning System accelerometer unit. Individual heart rate was also recorded using heart rate monitors. As a group mean, the basketball players covered 82.6 ± 7.8 m·min during the game with a mean heart rate of 89.8 ± 4.4% of maximal heart rate. Players covered 3 ± 3% of the total distance running at above 18 km·h and performed 0.17 ± 0.13 sprints per minute. The number of body impacts was 8.2 ± 1.8 per minute of play. The running pace of forwards was higher than that of centers (86.8 ± 6.2 vs. 76.6 ± 6.0 m·min; p ≤ 0.05). The maximal speed obtained during the game was significantly higher for guards than that for centers (24.0 ± 1.6 km·h vs. 21.3 ± 1.6 km·h; p ≤ 0.05). Centers performed a lower number of accelerations/decelerations than guards and forwards (p ≤ 0.05). In conclusion, the extraordinary rates of specific movements performed by these experienced basketball players indicate the high physiological demands necessary to be able to compete in this sport. The centers were the basketball players who showed lower physiological demands during a game, whereas there were no differences between guards and forwards. These results can be used by coaches to adapt basketball training programs to the specific demands of each playing position.

Does Short-Duration Heat Exposure at a Matched Cardiovascular Intensity Improve Intermittent-Running Performance in a Cool Environment?

PubMed

Philp, Calvin P; Buchheit, Martin; Kitic, Cecilia M; Minson, Christopher T; Fell, James W

2017-07-01

To investigate whether a 5-d cycling training block in the heat (35°C) in Australian Rules footballers was superior to exercising at the same relative intensity in cool conditions (15°C) for improving intermittent-running performance in a cool environment (<18°C). Using a parallel-group design, 12 semiprofessional football players performed 5 d of cycling exercise (70% heart-rate reserve [HRR] for 45 min [5 × 50-min sessions in total]) in a hot (HEAT, 35°C ± 1°C, 56% ± 9% RH) or cool environment (COOL, 15°C ± 3°C, 81% ± 10% RH). A 30-15 Intermittent Fitness Test to assess intermittent running performance (V IFT ) was conducted in a cool environment (17°C ± 2°C, 58 ± 5% RH) before and twice after (1 and 3 d) the intervention. There was a likely small increase in V IFT in each group (HEAT, 0.5 ± 0.3 km/h, 1.5 ± 0.8 × smallest worthwhile change [SWC]; COOL, 0.4 ± 0.4 km/h, 1.6 ± 1.2 × SWC) 3 d postintervention, with no difference in change between the groups (0.5% ± 1.9%, 0.4 ± 1.4 × SWC). Cycle power output during the intervention was almost certainly lower in the HEAT group (HEAT 1.8 ± 0.2 W/kg vs COOL 2.5 ± 0.3 W/kg, -21.7 ± 3.2 × SWC, 100/0/0). When cardiovascularexercise intensity is matched (ie, 70% HRR) between environmental conditions, there is no additional performance benefit from short-duration moderate-intensity heat exposure (5 × 50 min) for semiprofessional footballers exercising in cool conditions. However, the similar positive adaptations may occur in HEAT with 30% lower mechanical load, which may be of interest for load management during intense training or rehabilitation phases.

High resolution present climate and surface mass balance (SMB) of Svalbard modelled by MAR and implementation of a new online SMB downscaling method

NASA Astrophysics Data System (ADS)

Lang, C.; Fettweis, X.; Kittel, C.; Erpicum, M.

2017-12-01

We present the results of high resolution simulations of the climate and SMB of Svalbard with the regional climate model MAR forced by ERA-40 then ERA-Interim, as well as an online downscaling method allowing us to model the SMB and its components at a resolution twice as high (2.5 vs 5 km here) using only about 25% more CPU time. Spitsbergen, the largest island in Svalbard, has a very hilly topography and a high spatial resolution is needed to correctly represent the local topography and the complex pattern of ice distribution and precipitation. However, high resolution runs with an RCM fully coupled to an energy balance module like MAR require a huge amount of computation time. The hydrostatic equilibrium hypothesis used in MAR also becomes less valid as the spatial resolution increases. We therefore developed in MAR a method to run the snow module at a resolution twice as high as the atmospheric module. Near-surface temperature and humidity are corrected on a grid with a resolution twice as high, as a function of their local gradients and the elevation difference between the corresponding pixels in the 2 grids. We compared the results of our runs at 5 km and with SMB downscaled at 2.5 km over 1960 — 2016 and compared those to previous 10 km runs. On Austfonna, where the slopes are gentle, the agreement between observations and the 5 km SMB is better than with the 10 km SMB. It is again improved at 2.5 km but the gain is relatively small, showing the interest of our method rather than running a time consuming classic 2.5 km resolution simulation. On Spitsbergen, we show that a spatial resolution of 2.5 km is still not enough to represent the complex pattern of topography, precipitation and SMB. Due to a change in the summer atmospheric circulation, from a westerly flow over Svalbard to a northwesterly flow bringing colder air, the SMB of Svalbard was stable between 2006 and 2012, while several melt records were broken in Greenland, due to conditions more anticyclonic than usual. In 2013, the reverse situation happened and a southwesterly atmospheric circulation brought warmer air over Svalbard. The SMB broke the last 55 years' record. In 2016, the temperature was higher than average and a new record melt was broken despite a northwesterly flow. The northerly flow still mitigated the warming over Svalbard, which was much lower than most regions of the Arctic.

Possible options to slow down the advancement rate of Tarbela delta.

PubMed

Habib-Ur-Rehman; Rehman, Mirza Abdul; Naeem, Usman Ali; Hashmi, Hashim Nisar; Shakir, Abdul Sattar

2017-12-22

The pivot point of delta in Tarbela dam has reached at about 10.6 km from the dam face which may result in blocking of tunnels. Tarbela delta was modeled from 1979 to 2060 using hec-6 model. Initially, the model was calibrated for year 1999 and validated for years 2000, 2001, 2002, and 2006 by involving the data of sediment concentration, reservoir cross sections (73 range lines), elevation-area capacity curves, and inflows and outflows from the reservoir. Then, the model was used to generate future scenarios, i.e., run-1, run-2, and run-3 with pool levels; 428, 442, and 457 m, respectively, till 2060. Results of run-1 and run-2 showed advancement to choke the tunnels by 2010 and 2030, respectively. Finally, in run-3, the advancement was further delayed showing that tunnels 1 and 2 will be choked by year 2050 and pivot point will reach at 6.4 km from the dam face.

The Association of ACE Genotypes on Cardiorespiratory Variables Related to Physical Fitness in Healthy Men

PubMed Central

Bueno, Salomão; Pasqua, Leonardo A.; de Araújo, Gustavo; Eduardo Lima-Silva, Adriano; Bertuzzi, Rômulo

2016-01-01

Aerobic power (VO2max), aerobic capacity (RCP), and running efficiency (RE) are important markers of aerobic fitness. However, the influence of the angiotensin converting enzyme (ACE) polymorphism on these markers has not been investigated in healthy individuals. One hundred and fifty physically active young men (age 25 ± 3 years; height 1.77 ± 0.06 m; body mass 76.6 ± 0.9 kg; VO2max 47.7 ± 5.5 ml·kg-1·min-1) visited the laboratory on two separate occasions, and performed the following tests: a) a maximal incremental treadmill test to determine VO2max and RCP, and b) two constant-speed running tests (10 km·h-1 and 12 km·h-1) to determine RE. The genotype frequency was II = 21%; ID = 52%; and DD = 27%. There was a tendency for higher VO2max with the ACE II genotype (p = 0.08) compared to DD and ID genotypes. Magnitude based inferences suggested a likely beneficial effect on VO2max with the ACE II genotype. There was no association between genotypes for other variable. These findings suggest that individuals with the ACE II genotype have a tendency towards better values in aerobic power, but not with aerobic capacity or running economy. PMID:27861507

Thermoregulatory Response to Exercise After Exertional Heat Stroke.

PubMed

Sagui, Emmanuel; Beighau, Sophie; Jouvion, Arnaud; Trichereau, Julie; Cornet, Delphine; Berthelot, René Charles; Canini, Frédéric; Grélot, Laurent

2017-07-01

After one episode of exertional heat stroke (EHS), risk factors must be identified to determine the potential for subsequent episodes. One of these risk factors, core body temperature (T co ) kinetics during strenuous exercise, may be a surrogate marker suggestive of impaired thermoregulation. This study aimed to determine the kinetics of increases in T co among military subjects who had a history of EHS. Forty subjects (38 males, mean age 28.4 ± 4.9 years, mean body mass index 24.9 ± 2.4) who had a history of EHS ran 8 km in full combat gear with continuous monitoring of T co and heart rate. The run was a qualifying event for military service. T co was assessed using an ingestible sensor (Cortemp HQ Inc., Palmetto, Florida). Maximum oxygen uptake (VO 2max ) was measured on the day before the run. The mean performance time for the run was 44.6 ± 6.6 minutes achieved under mild climatic conditions. No neurological impairment was observed. The mean maximum T co was 39.9 ± 0.5°C. On the basis of T co during the last 10 minutes of running, two T co profiles were identified: increased T co (T co increase > 0.5°C) and plateaued T co . Neither profile depended on initial, mid-run, or maximal T co , VO 2max , speed running, body surface area or body fat mass. Subjects who had a history of EHS exhibited different T co profiles at the end of an 8-km run. Laboratory studies will be necessary to identify the mechanisms underlying these profiles; future longitudinal studies can determine whether a T co increase >0.5°C during the last 10 minutes is a risk factor for EHS recurrence. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

Participation and performance trends in ‘Ultraman Hawaii’ from 1983 to 2012

PubMed Central

2013-01-01

Background Participation and performance trends have been investigated in a single stage Ironman triathlon such as the ‘Ironman Hawaii,’ but not for a multi-stage ultra-triathlon such as the ‘Ultraman Hawaii’ covering a total distance of 515 km. The aims of this study were to analyze (1) changes in participation and performance, (2) sex-related differences in overall and split time performances, and (3) the age of peak performance in Ultraman Hawaii. Methods Age and race times including split times for 98 women and 570 men who successfully finished Ultraman Hawaii (day 1 with 10-km swimming and 145-km cycling, day 2 with 276-km cycling, and day 3 with 84-km running) between 1983 and 2012 were analyzed. Changes in variables over time of annual winners and annual top three women and men were investigated using simple linear regression analyses. Results The number of female finishers increased (r2 = 0.26, p < 0.01), while the number of male finishers remained stable (r2 = 0.03, p > 0.05). Overall race times decreased for both female (r2 = 0.28, p < 0.01) and male (r2 = 0.14, p < 0.05) winners and for both the annual top three women (r2 = 0.36, p < 0.01) and men (r2 = 0.14, p = 0.02). The sex difference in performance decreased over time from 24.3% to 11.5% (r2 = 0.39, p < 0.01). For the split disciplines, the time performance in cycling on day 1 (r2 = 0.20, p < 0.01) and day 2 decreased significantly for men (r2 = 0.41, p < 0.01) but for women only on day 2 (r2 = 0.45, p < 0.01). Split times showed no changes in swimming and running. The age of the annual winners increased from 28 to 47 years for men (r2 = 0.35, p < 0.01) while it remained stable at 32 ± 6 years for women (r2 < 0.01, p > 0.05). The age of the annual top three finishers increased from 33 ± 6 years to 48 ± 3 years for men (p < 0.01) and from 29 ± 7 years to 49 ± 2 years for women (p < 0.01). Conclusions Both the annual top three women and men improved performance in Ultraman Hawaii during the 1983–2012 period although the age of the annual top three women and men increased. The sex-related difference in performance decreased over time to reach approximately 12% similar to the reports of other endurance and ultra-endurance events. Further investigations are required to better understand the limiting factors of the multi-activities ultra-endurance events taking place over several days. PMID:23916227

Physical qualities and activity profiles of sub-elite and recreational Australian football players.

PubMed

Stein, Josh G; Gabbett, Tim J; Townshend, Andrew D; Dawson, Brian T

2015-11-01

To investigate the relationship between physical qualities and match activity profiles of recreational Australian football players. Prospective cohort study. Forty players from three recreational Australian football teams (Division One, Two and Three) underwent a battery of fitness tests (vertical jump, 10 and 40 m sprint, 6 m × 30 m repeated sprint test, Yo-Yo intermittent recovery level Two and 2-km time trial). The activity profiles of competitive match-play were quantified using 10-Hz Global Positioning System units. Division One players possessed greater maximum velocity, Yo-Yo level Two and 2-km time trial performances than Division Two and Three players. In addition, Division One players covered greater relative distance, and relative distances at moderate- and high-intensities during match-play than Division Two and Three players. Division Two players had better 2-km time trial performances than Division Three players. Positive associations (P < 0.05) were found between 10 m acceleration, maximum velocity, Yo-Yo level Two and 2-km time trial performances and relative distance, and relative distances covered at moderate- and high-intensities during match-play. Moderate relationships were found between vertical jump and relative distance and high-intensity running. Sub-elite Australian football players competing at a higher level exhibit greater physical qualities and match-play activity profiles than lesser-skilled recreational players. Acceleration and maximum velocity, 2-km time trial and Yo-Yo level Two performances discriminate between players of different playing levels, and are related to physical match performance in recreational Australian football. The development of these qualities is likely to contribute to improved match performance in recreational Australian football players. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

The long-term effect of minimalist shoes on running performance and injury: design of a randomised controlled trial

PubMed Central

Fuller, Joel T; Thewlis, Dominic; Tsiros, Margarita D; Brown, Nicholas A T; Buckley, Jonathan D

2015-01-01

Introduction The outcome of the effects of transitioning to minimalist running shoes is a topic of interest for runners and scientists. However, few studies have investigated the longer term effects of running in minimalist shoes. The purpose of this randomised controlled trial (RCT) is to investigate the effects of a 26 week transition to minimalist shoes on running performance and injury risk in trained runners unaccustomed to minimalist footwear. Methods and analysis A randomised parallel intervention design will be used. Seventy-six trained male runners will be recruited. To be eligible, runners must be aged 18–40 years, run with a habitual rearfoot footfall pattern, train with conventional shoes and have no prior experience with minimalist shoes. Runners will complete a standardised transition to either minimalist or control shoes and undergo assessments at baseline, 6 and 26 weeks. 5 km time-trial performance (5TT), running economy, running biomechanics, triceps surae muscle strength and lower limb bone mineral density will be assessed at each time point. Pain and injury will be recorded weekly. Training will be standardised during the first 6 weeks. Primary statistical analysis will compare 5TT between shoe groups at the 6-week time point and injury incidence across the entire 26-week study period. Ethics and dissemination This RCT has been approved by the Human Research Ethics Committee of the University of South Australia. Participants will be required to provide their written informed consent prior to participation in the study. Study findings will be disseminated in the form of journal publications and conference presentations after completion of planned data analysis. Trial registration number This RCT has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN12613000642785). PMID:26297368

Six-week transition to minimalist shoes improves running economy and time-trial performance.

PubMed

Fuller, Joel T; Thewlis, Dominic; Tsiros, Margarita D; Brown, Nicholas A T; Buckley, Jonathan D

2017-12-01

This study investigated if gradually introducing runners to minimalist shoes during training improved running economy and time-trial performance compared to training in conventional shoes. Changes in stride rate, stride length, footfall pattern and ankle plantar-flexor strength were also investigated. Randomised parallel intervention trial. 61 trained runners gradually increased the amount of running performed in either minimalist (n=31) or conventional (n=30) shoes during a six-week standardised training program. 5-km time-trial performance, running economy, ankle plantar-flexor strength, footfall pattern, stride rate and length were assessed in the allocated shoes at baseline and after training. Footfall pattern was determined from the time differential between rearfoot and forefoot (TD R-F ) pressure sensors. The minimalist shoe group improved time-trial performance (effect size (ES): 0.24; 95% confidence interval (CI): 0.01, 0.48; p=0.046) and running economy (ES 0.48; 95%CI: 0.22, 0.74; p<0.001) more than the conventional shoe group. There were no minimalist shoe training effects on ankle plantar-flexor concentric (ES: 0.11; 95%CI: -0.18, 0.41; p=0.45), isometric (ES: 0.23; 95%CI: -0.17, 0.64; p=0.25), or eccentric strength (ES: 0.24; 95%CI: -0.17, 0.65; p=0.24). Minimalist shoes caused large reductions in TD R-F (ES: 1.03; 95%CI: 0.65, 1.40; p<0.001) but only two runners changed to a forefoot footfall. Minimalist shoes had no effect on stride rate (ES: 0.04; 95%CI: -0.08, 0.16; p=0.53) or length (ES: 0.06; 95%CI: -0.06, 0.18; p=0.35). Gradually introducing minimalist shoes over a six-week training block is an effective method for improving running economy and performance in trained runners. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Analysis of the assessment of caloric expenditure in four modes of aerobic dance.

PubMed

Rixon, Kendall P; Rehor, Peter R; Bemben, Michael G

2006-08-01

Aerobic dance has been purported to help with weight management; however, it is not known if various forms of dance are as effective as traditional modalities. This study estimated energy expenditure by heart rate for 28 women participating in 4 modes of aerobic dance (Bodycombat [i.e., TAEBO]; Pump; Step; and RPM [i.e., spinning]) compared to 2 running speeds. Pump had significantly (p < 0.01) lower energy expenditure (8.0 +/- 1.6 kcal.min(-1)) compared to the other classes (RPM: 9.9 +/- 1.9 kcal.min(-1); Step: 9.6 +/- 1.8 kcal.min(-1); and Bodycombat: 9.7 +/- 2.0 kcal.min(-1)) and running at 8.05 km.h(-1) (9.16 +/- 1.53 kcal.min(-1)). Also, Step (p < 0.01), Bodycombat (p < 0.01), and RPM (p < 0.01) had significantly higher caloric expenditures than running at 8.05 km.h(-1) but significantly lower than running at 8.37 km.h(-1) (10.30 +/- 1.72 kcal.min(-1)). In conclusion, RPM, Bodycombat, and Step aerobics were equally as effective as jogging between 8.05 and 8.37 km.h(-1), and they met American College of Sports Medicine guidelines for weight modification and maintenance. Additionally, heart rate assessment provided a quantitative method for estimating energy expenditure and the effectiveness of different aerobic programs.

Pacing, packing and sex-based differences in Olympic and IAAF World Championship marathons.

PubMed

Hanley, Brian

2016-09-01

The aim of this study was to describe pacing profiles and packing behaviours of athletes in Olympic and World Championship marathons. Finishing and split times were collated for 673 men and 549 women across nine competitions. The mean speeds for each intermediate 5 km and end 2.2 km segments were calculated. Medallists of both sexes maintained even-paced running from 10 km onwards whereas slower finishers dropped off the lead pack at approximately half-distance. Athletes who ran with the same opponents throughout slowed the least in the second half (P < 0.001, men: ES ≥ 1.19; women: ES ≥ 1.06), whereas other strategies such as moving between packs or running alone were less successful. Overall, women slowed less (P < 0.001, ES = 0.44) and were more likely to run a negative split (P < 0.001), and their more conservative start meant fewer women dropped out (P < 0.001). This also meant that women medallists sped up in the final 2.2 km, which might have decided the medal positions. Marathon runners are advised to identify rivals with similar abilities and ambitions to run alongside provided they start conservatively. Coaches should note important sex-based differences in tactics adopted and design training programmes accordingly.

The mechanics of running in children

PubMed Central

Schepens, B; Willems, P A; Cavagna, G A

1998-01-01

The effect of age and body size on the bouncing mechanism of running was studied in children aged 2-16 years.The natural frequency of the bouncing system (fs) and the external work required to move the centre of mass of the body were measured using a force platform.At all ages, during running below ≈11 km h−1, the freely chosen step frequency (f) is about equal to fs (symmetric rebound), independent of speed, although it decreases with age from 4 Hz at 2 years to 2.5 Hz above 12 years.The decrease of step frequency with age is associated with a decrease in the mass-specific vertical stiffness of the bouncing system (k/m) due to an increase of the body mass (m) with a constant stiffness (k). Above 12 years, k/m and f remain approximately constant due to a parallel increase in both k and m with age.Above the critical speed of ≈11 km h−1, independent of age, the rebound becomes asymmetric, i.e. f < fs.The maximum running speed (V¯f,max) increases with age while the step frequency at remains constant (≈4 Hz), independent of age.At a given speed, the higher step frequency in preteens results in a mass-specific power against gravity less than that in adults. The external power required to move the centre of mass of the body is correspondingly reduced. PMID:9596810

Addiction-prone Lewis but not Fischer rats develop compulsive running that coincides with downregulation of nerve growth factor inducible-B and neuron-derived orphan receptor 1.

PubMed

Werme, M; Thorén, P; Olson, L; Brené, S

1999-07-15

We have examined the effects of chronic voluntary running for 30 d on the levels of nerve growth factor inducilble-B (NGFI-B) and neuron-derived orphan receptor 1 (NOR1) mRNAs in Fischer and Lewis rats. The aim was to compare the addiction-prone Lewis rat strain to the Fischer strain in a plausible model for natural reward. The Lewis strain ran markedly more than the Fischer strain, as indicated by the length of running per day when given free access to running wheels. Both strains progressively increased their amount of daily running. By day 14, Lewis rats had reached a maximal level corresponding to 10 km/d, which slowly decreased to approximately 8 km/d. Fischer rats ran considerably less, averaging approximately 1. 5 km/d by day 30. After 30 d of running, levels of mRNA encoding NGFI-B and Nor1 were decreased in cerebral cortex in Lewis but not Fischer rats. The downregulation of NGFI-B mRNA in Lewis rats could not be attenuated by the opioid receptor antagonist naloxone. Instead, naloxone by itself downregulated NGFI-B in striatum and cerebral cortex in both strains. In contrast, naloxone had no effect on Nor1 mRNA levels, although the running-induced downregulation of Nor1 was, in most cases, attenuated by naloxone. Data from the present study suggest that the same genetic factors contributing to the drug addiction-prone behavior of Lewis rats also control the excessive running behavior and that this coincides with downregulation of transcription factors of the NGFI-B family.

Usefulness of running wheel for detection of congestive heart failure in dilated cardiomyopathy mouse model.

PubMed

Sugihara, Masami; Odagiri, Fuminori; Suzuki, Takeshi; Murayama, Takashi; Nakazato, Yuji; Unuma, Kana; Yoshida, Ken-ichi; Daida, Hiroyuki; Sakurai, Takashi; Morimoto, Sachio; Kurebayashi, Nagomi

2013-01-01

Inherited dilated cardiomyopathy (DCM) is a progressive disease that often results in death from congestive heart failure (CHF) or sudden cardiac death (SCD). Mouse models with human DCM mutation are useful to investigate the developmental mechanisms of CHF and SCD, but knowledge of the severity of CHF in live mice is necessary. We aimed to diagnose CHF in live DCM model mice by measuring voluntary exercise using a running wheel and to determine causes of death in these mice. A knock-in mouse with a mutation in cardiac troponin T (ΔK210) (DCM mouse), which results in frequent death with a t(1/2) of 70 to 90 days, was used as a DCM model. Until 2 months of age, average wheel-running activity was similar between wild-type and DCM mice (approximately 7 km/day). At approximately 3 months, some DCM mice demonstrated low running activity (LO: <1 km/day) while others maintained high running activity (HI: >5 km/day). In the LO group, the lung weight/body weight ratio was much higher than that in the other groups, and the lungs were infiltrated with hemosiderin-loaded alveolar macrophages. Furthermore, echocardiography showed more severe ventricular dilation and a lower ejection fraction, whereas Electrocardiography (ECG) revealed QRS widening. There were two patterns in the time courses of running activity before death in DCM mice: deaths with maintained activity and deaths with decreased activity. Our results indicate that DCM mice with low running activity developed severe CHF and that running wheels are useful for detection of CHF in mouse models. We found that approximately half of ΔK210 DCM mice die suddenly before onset of CHF, whereas others develop CHF, deteriorate within 10 to 20 days, and die.

Challenge toward the prediction of typhoon behaviour and down pour

NASA Astrophysics Data System (ADS)

Takahashi, K.; Onishi, R.; Baba, Y.; Kida, S.; Matsuda, K.; Goto, K.; Fuchigami, H.

2013-08-01

Mechanisms of interactions among different scale phenomena play important roles for forecasting of weather and climate. Multi-scale Simulator for the Geoenvironment (MSSG), which deals with multi-scale multi-physics phenomena, is a coupled non-hydrostatic atmosphere-ocean model designed to be run efficiently on the Earth Simulator. We present simulation results with the world-highest 1.9km horizontal resolution for the entire globe and regional heavy rain with 1km horizontal resolution and 5m horizontal/vertical resolution for urban area simulation. To gain high performance by exploiting the system capabilities, we propose novel performance evaluation metrics introduced in previous studies that incorporate the effects of the data caching mechanism between CPU and memory. With a useful code optimization guideline based on such metrics, we demonstrate that MSSG can achieve an excellent peak performance ratio of 32.2% on the Earth Simulator with the single-core performance found to be a key to a reduced time-to-solution.

Comparison of running and cycling economy in runners, cyclists, and triathletes.

PubMed

Swinnen, Wannes; Kipp, Shalaya; Kram, Rodger

2018-07-01

Exercise economy is one of the main physiological factors determining performance in endurance sports. Running economy (RE) can be improved with running-specific training, while the improvement of cycling economy (CE) with cycling-specific training is controversial. We investigated whether exercise economy reflects sport-specific skills/adaptations or is determined by overall physiological factors. We compared RE and CE in 10 runners, 9 cyclists and 9 triathletes for running at 12 km/h and cycling at 200 W. Gross rates of oxygen consumption and carbon dioxide production were collected and used to calculate gross metabolic rate in watts for both running and cycling. Runners had better RE than cyclists (917 ± 107 W vs. 1111 ± 159 W) (p < 0.01). Triathletes had intermediate RE values (1004 ± 98 W) not different from runners or cyclists. CE was not different (p = 0.20) between the three groups (runners: 945 ± 60 W; cyclists: 982 ± 44 W; triathletes: 979 ± 54 W). RE can be enhanced with running-specific training, but CE is independent of cycling-specific training.

Temperate Performance Benefits after Heat, but Not Combined Heat and Hypoxic Training.

PubMed

McCleave, Erin L; Slattery, Katie M; Duffield, Rob; Saunders, Philo U; Sharma, Avish P; Crowcroft, Stephen J; Coutts, Aaron J

2017-03-01

Independent heat and hypoxic exposure can enhance temperate endurance performance in trained athletes, although their combined effects remain unknown. This study examined whether the addition of heat interval training during "live high, train low" (LHTL) hypoxic exposure would result in enhanced performance and physiological adaptations as compared with heat or temperate training. Twenty-six well-trained runners completed 3 wk of interval training assigned to one of three conditions: 1) LHTL hypoxic exposure plus heat training (H + H; 3000 m for 13 h·d, train at 33°C, 60% relative humidity [RH]), 2) heat training with no hypoxic exposure (HOT, live at <600 m and train at 33°C, 60% RH), or 3) temperate training with no hypoxic exposure (CONT; live at <600 m and train at 14°C, 55% RH). Performance 3-km time-trials (3-km TT), running economy, hemoglobin mass, and plasma volume were assessed using magnitude-based inferences statistical approach before (Baseline), after (Post), and 3 wk (3wkP) after exposure. Compared with Baseline, 3-km TT performance was likely increased in HOT at 3wkP (-3.3% ± 1.3%; mean ± 90% confidence interval), with no performance improvement in either H + H or CONT. Hemoglobin mass increased by 3.8% ± 1.8% at Post in H + H only. Plasma volume in HOT was possibly elevated above H + H and CONT at Post but not at 3wkP. Correlations between changes in 3-km TT performance and physiological adaptations were unclear. Incorporating heat-based training into a 3-wk training block can improve temperate performance at 3 wk after exposure, with athlete psychology, physiology, and environmental dose all important considerations. Despite hematological adaptations, the addition of LHTL to heat interval training has no greater 3-km TT performance benefit than temperate training alone.

Running speed increases plantar load more than per cent body weight on an AlterG® treadmill.

PubMed

Thomson, Athol; Einarsson, Einar; Witvrouw, Erik; Whiteley, Rod

2017-02-01

AlterG® treadmills allow for running at different speeds as well as at reduced bodyweight (BW), and are used during rehabilitation to reduce the impact load. The aim of this study was to quantify plantar loads borne by the athlete during rehabilitation. Twenty trained male participants ran on the AlterG® treadmill in 36 conditions: all combinations of indicated BW (50-100%) paired with different walking and running speeds (range 6-16 km · hr -1 ) in a random order. In-shoe maximum plantar force (Fmax) was recorded using the Pedar-X system. Fmax was lowest at the 6 km · hr -1 at 50% indicated BW condition at 1.02 ± 0.21BW and peaked at 2.31 ± 0.22BW for the 16 km · hr -1 at 100% BW condition. Greater increases in Fmax were seen when increasing running speed while holding per cent BW constant than the reverse (0.74BW-0.91BW increase compared to 0.19-0.31BW). A table is presented with each of the 36 combinations of BW and running speed to allow a more objective progression of plantar loading during rehabilitation. Increasing running speed rather than increasing indicated per cent BW was shown to have the strongest effect on the magnitude of Fmax across the ranges of speeds and indicated per cent BWs examined.

Effects of gradual-elastic compression stockings on running economy, kinematics, and performance in runners.

PubMed

Varela-Sanz, Adrian; España, Javier; Carr, Natasha; Boullosa, Daniel A; Esteve-Lanao, Jonathan

2011-10-01

We investigated the effect of gradual-elastic compression stockings (GCSs) on running economy (RE), kinematics, and performance in endurance runners. Sixteen endurance trained athletes (age: 34.73 ± 6.27 years; VO2max: 62.83 ± 9.03 ml·kg(-1)·min(-1); 38 minutes in 10 km; 1 hour 24 minutes in half marathon) performed in random order 4 bouts of 6 minutes at a recent half-marathon pace on a treadmill to evaluate RE with or without GCSs. Subsequently, 12 athletes were divided into 2 equal groups matched by their VO2max, and they performed a time limit test (T(lim)) on a treadmill at 105% of a recent 10-km pace with or without GCSs for evaluation of physiological responses and running kinematics. There were no significant differences in the RE test in all of the variables analyzed for the conditions, but a moderate reproducibility for some physiological responses was detected in the condition with GCSs. In the T(lim), the group that wore GCSs reached a lower % of maximum heart rate (HRmax) compared with the control group (96.00 ± 2.94 vs. 99.83 ± 0.40) (p = 0.01). Kinematics did not differ between conditions during the T(lim) (p > 0.05). There were improvement trends for time to fatigue (337 vs. 387 seconds; d = 0.32) and a lower VO2peak (≈53 vs. 62 ml·kg(-1)·min(-1); d = 1.19) that were detected with GCSs during the T(lim). These results indicate that GCSs reduce the % of HRmax reached during a test at competition pace. The lower reproducibility of the condition with GCSs perhaps suggests that athletes may possibly need an accommodation period for systematically experiencing the benefits of this garment, but this hypothesis should be further investigated.

Effects of mixed-method cooling on recovery of medium-fast bowling performance in hot conditions on consecutive days.

PubMed

Minett, Geoffrey M; Duffield, Rob; Kellett, Aaron; Portus, Marc

2012-01-01

This investigation examined physiological and performance effects of cooling on recovery of medium-fast bowlers in the heat. Eight, medium-fast bowlers completed two randomised trials, involving two sessions completed on consecutive days (Session 1: 10-overs and Session 2: 4-overs) in 31 ± 3°C and 55 ± 17% relative humidity. Recovery interventions were administered for 20 min (mixed-method cooling vs. control) after Session 1. Measures included bowling performance (ball speed, accuracy, run-up speeds), physical demands (global positioning system, counter-movement jump), physiological (heart rate, core temperature, skin temperature, sweat loss), biochemical (creatine kinase, C-reactive protein) and perceptual variables (perceived exertion, thermal sensation, muscle soreness). Mean ball speed was higher after cooling in Session 2 (118.9 ± 8.1 vs. 115.5 ± 8.6 km · h⁻¹; P = 0.001; d = 0.67), reducing declines in ball speed between sessions (0.24 vs. -3.18 km · h⁻¹; P = 0.03; d = 1.80). Large effects indicated higher accuracy in Session 2 after cooling (46.0 ± 11.2 vs. 39.4 ± 8.6 arbitrary units [AU]; P = 0.13; d = 0.93) without affecting total run-up speed (19.0 ± 3.1 vs. 19.0 ± 2.5 km · h⁻¹; P = 0.97; d = 0.01). Cooling reduced core temperature, skin temperature and thermal sensation throughout the intervention (P = 0.001-0.05; d = 1.31-5.78) and attenuated creatine kinase (P = 0.04; d = 0.56) and muscle soreness at 24-h (P = 0.03; d = 2.05). Accordingly, mixed-method cooling can reduce thermal strain after a 10-over spell and improve markers of muscular damage and discomfort alongside maintained medium-fast bowling performance on consecutive days in hot conditions.

Effects of caffeine on the inflammatory response induced by a 15-km run competition.

PubMed

Tauler, Pedro; Martínez, Sonia; Moreno, Carlos; Monjo, Marta; Martínez, Pau; Aguiló, Antoni

2013-07-01

The objective of this study is as follows: 1) to determine the effects of caffeine supplementation on the inflammatory response (IL-6 and IL-10 levels and leukocyte numbers) induced by a 15-km run competition and 2) to examine the effect of caffeine supplementation on the energetic metabolites as well as on the exercise-induced oxidative stress. A double-blinded study of supplementation with caffeine was performed. Athletes participating in the study (n = 33) completed a 15-km run competition. Before competition, athletes took 6 mg · kg(-1) body weight of caffeine (caffeine group, n = 17) or a placebo (placebo group, n = 16). Blood samples were taken before and after competition (immediately and after 2-h recovery). Leukocyte numbers were determined in blood. Concentrations of oxidative stress markers, antioxidants, interleukins (IL-6 and IL-10), caffeine, adrenaline, and energetic metabolites were measured in plasma or serum. Caffeine supplementation induced higher increases in circulating total leukocytes and neutrophils, with significant differences between groups after recovery. Adrenaline, glucose, and lactate levels increased after exercise, with higher increases in the caffeine group. Exercise induced significant increases in IL-6 and IL-10 plasma levels, with higher increases in the caffeine group. Caffeine supplementation induced higher increases in oxidative stress markers after the competition. Caffeine supplementation induced higher levels of IL-6 and IL-10 in response to exercise, enhancing the anti-inflammatory response. The caffeine-induced increase in adrenaline could be responsible for the higher increase in IL-6 levels, as well as for the increased lactate levels. Furthermore, caffeine seems to enhance oxidative stress induced by exercise.

Cardiac function is preserved following 4 weeks of voluntary wheel running in a rodent model of chronic kidney disease.

PubMed

Kuczmarski, James M; Martens, Christopher R; Kim, Jahyun; Lennon-Edwards, Shannon L; Edwards, David G

2014-09-01

The purpose of this investigation was to determine the effect of 4 wk of voluntary wheel running on cardiac performance in the 5/6 ablation-infarction (AI) rat model of chronic kidney disease (CKD). We hypothesized that voluntary wheel running would be effective in preserving cardiac function in AI. Male Sprague-Dawley rats were divided into three study groups: 1) sham, sedentary nondiseased control; 2) AI-SED, sedentary AI; and 3) AI-WR, wheel-running AI. Animals were maintained over a total period of 8 wk following AI and sham surgery. The 8-wk period included 4 wk of disease development followed by a 4-wk voluntary wheel-running intervention/sedentary control period. Cardiac performance was assessed using an isolated working heart preparation. Left ventricular (LV) tissue was used for biochemical tissue analysis. In addition, soleus muscle citrate synthase activity was measured. AI-WR rats performed a low volume of exercise, running an average of 13 ± 2 km, which resulted in citrate synthase activity not different from that in sham animals. Isolated AI-SED hearts demonstrated impaired cardiac performance at baseline and in response to preload/afterload manipulations. Conversely, cardiac function was preserved in AI-WR vs. sham hearts. LV nitrite + nitrate and expression of LV nitric oxide (NO) synthase isoforms 2 and 3 in AI-WR were not different from those of sham rats. In addition, LV H2O2 in AI-WR was similar to that of sham and associated with increased expression of LV superoxide-dismutase-2 and glutathione peroxidase-1/2. The findings of the current study suggest that a low-volume exercise intervention is sufficient to maintain cardiac performance in rats with CKD, potentially through a mechanism related to improved redox homeostasis and increased NO. Copyright © 2014 the American Physiological Society.

Impact of police body armour and equipment on mobility.

PubMed

Dempsey, Paddy C; Handcock, Phil J; Rehrer, Nancy J

2013-11-01

Body armour is used widely by law enforcement and other agencies but has received mixed reviews. This study examined the influence of stab resistant body armour (SRBA) and mandated accessories on physiological responses to, and the performance of, simulated mobility tasks. Fifty-two males (37 ± 9.2 yr, 180.7 ± 6.1 cm, 90.2 ± 11.6 kg, VO2max 50 ± 8.5 ml kg(-1) min(-1), BMI 27.6 ± 3.1, mean ± SD) completed a running VO2max test and task familiarisation. Two experimental sessions were completed (≥4 days in between) in a randomised counterbalanced order, one while wearing SRBA and appointments (loaded) and one without additional load (unloaded). During each session participants performed five mobility tasks: a balance task, an acceleration task that simulated exiting a vehicle, chin-ups, a grappling task, and a manoeuvrability task. A 5-min treadmill run (zero-incline at 13 km·h(-1), running start) was then completed. One min after the run the five mobility tasks were repeated. There was a significant decrease in performance during all tasks with loading (p < 0.001). Participants were off-balance longer; slower to complete the acceleration, grapple and mobility tasks; completed fewer chin-ups; and had greater physiological cost (↑ %HRmax, ↑ %VO2max, ↑ RER) and perceptual effort (↑ RPE) during the 5-min run. Mean performance decreases ranged from 13 to 42% while loaded, with further decreases of 6-16% noted after the 5-min run. Unloaded task performance was no different between phases. Wearing SRBA and appointments significantly reduced mobility during key task elements and resulted in greater physiological effort. These findings could have consequences for optimal function in the working environment and therefore officer and public safety. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Redistribution of Mechanical Work at the Knee and Ankle Joints During Fast Running in Minimalist Shoes.

PubMed

Fuller, Joel T; Buckley, Jonathan D; Tsiros, Margarita D; Brown, Nicholas A T; Thewlis, Dominic

2016-10-01

Minimalist shoes have been suggested as a way to alter running biomechanics to improve running performance and reduce injuries. However, to date, researchers have only considered the effect of minimalist shoes at slow running speeds. To determine if runners change foot-strike pattern and alter the distribution of mechanical work at the knee and ankle joints when running at a fast speed in minimalist shoes compared with conventional running shoes. Crossover study. Research laboratory. Twenty-six trained runners (age = 30.0 ± 7.9 years [age range, 18-40 years], height = 1.79 ± 0.06 m, mass = 75.3 ± 8.2 kg, weekly training distance = 27 ± 15 km) who ran with a habitual rearfoot foot-strike pattern and had no experience running in minimalist shoes. Participants completed overground running trials at 18 km/h in minimalist and conventional shoes. Sagittal-plane kinematics and joint work at the knee and ankle joints were computed using 3-dimensional kinematic and ground reaction force data. Foot-strike pattern was classified as rearfoot, midfoot, or forefoot strike based on strike index and ankle angle at initial contact. We observed no difference in foot-strike classification between shoes (χ 2 1 = 2.29, P = .13). Ankle angle at initial contact was less (2.46° versus 7.43°; t 25 = 3.34, P = .003) and strike index was greater (35.97% versus 29.04%; t 25 = 2.38, P = .03) when running in minimalist shoes compared with conventional shoes. We observed greater negative (52.87 J versus 42.46 J; t 24 = 2.29, P = .03) and positive work (68.91 J versus 59.08 J; t 24 = 2.65, P = .01) at the ankle but less negative (59.01 J versus 67.02 J; t 24 = 2.25, P = .03) and positive work (40.37 J versus 47.09 J; t 24 = 2.11, P = .046) at the knee with minimalist shoes compared with conventional shoes. Running in minimalist shoes at a fast speed caused a redistribution of work from the knee to the ankle joint. This finding suggests that runners changing from conventional to minimalist shoes for short-distance races could be at an increased risk of ankle and calf injuries but a reduced risk of knee injuries.

Wave run-up on a high-energy dissipative beach

USGS Publications Warehouse

Ruggiero, P.; Holman, R.A.; Beach, R.A.

2004-01-01

Because of highly dissipative conditions and strong alongshore gradients in foreshore beach morphology, wave run-up data collected along the central Oregon coast during February 1996 stand in contrast to run-up data currently available in the literature. During a single data run lasting approximately 90 min, the significant vertical run-up elevation varied by a factor of 2 along the 1.6 km study site, ranging from 26 to 61% of the offshore significant wave height, and was found to be linearly dependent on the local foreshore beach slope that varied by a factor of 5. Run-up motions on this high-energy dissipative beach were dominated by infragravity (low frequency) energy with peak periods of approximately 230 s. Incident band energy levels were 2.5 to 3 orders of magnitude lower than the low-frequency spectral peaks and typically 96% of the run-up variance was in the infragravity band. A broad region of the run-up spectra exhibited an f-4 roll off, typical of saturation, extending to frequencies lower than observed in previous studies. The run-up spectra were dependent on beach slope with spectra for steeper foreshore slopes shifted toward higher frequencies than spectra for shallower foreshore slopes. At infragravity frequencies, run-up motions were coherent over alongshore length scales in excess of 1 km, significantly greater than decorrelation length scales on moderate to reflective beaches. Copyright 2004 by the American Geophysical Union.

SPH/N-Body simulations of small (D = 10km) asteroidal breakups and improved parametric relations for Monte-Carlo collisional models

NASA Astrophysics Data System (ADS)

Ševeček, P.; Brož, M.; Nesvorný, D.; Enke, B.; Durda, D.; Walsh, K.; Richardson, D. C.

2017-11-01

We report on our study of asteroidal breakups, i.e. fragmentations of targets, subsequent gravitational reaccumulation and formation of small asteroid families. We focused on parent bodies with diameters Dpb = 10km . Simulations were performed with a smoothed-particle hydrodynamics (SPH) code combined with an efficient N-body integrator. We assumed various projectile sizes, impact velocities and impact angles (125 runs in total). Resulting size-frequency distributions are significantly different from scaled-down simulations with Dpb = 100km targets (Durda et al., 2007). We derive new parametric relations describing fragment distributions, suitable for Monte-Carlo collisional models. We also characterize velocity fields and angular distributions of fragments, which can be used as initial conditions for N-body simulations of small asteroid families. Finally, we discuss a number of uncertainties related to SPH simulations.

Vegan triple-ironman (raw vegetables/fruits).

PubMed

Leischik, Roman; Spelsberg, Norman

2014-01-01

Endurance sport requires a healthy and balanced diet. In this case report we present the findings of an ultra-triathlete (three times Ironman, means 11.4 km swim, 540 km bike, 125 km run in 41:18 h as a whole) living on a raw vegan diet and having finished the competitions under these nutritional conditions. To this end, the vegan ultra triathlete and a control group of 10 Ironman triathletes of similar age living on a mixed diet were investigated, using echocardiography and spiroergometry. In addition, blood samples were taken from the vegan athlete both in the sporting season and in the off-season. The vegan athlete showed no signs of dietary deficiencies or impaired health. In comparison with the control group, the vegan athlete showed a higher oxygen intake at the respiratory compensation point. This case demonstrates that even top-class sporting performance, like that of a three-time Ironman, is possible on a vegan diet. Whether a vegan diet offers advantages or disadvantages for the performance of endurance athletes remains an open question.

Vegan Triple-Ironman (Raw Vegetables/Fruits)

PubMed Central

Leischik, Roman; Spelsberg, Norman

2014-01-01

Endurance sport requires a healthy and balanced diet. In this case report we present the findings of an ultra-triathlete (three times Ironman, means 11.4 km swim, 540 km bike, 125 km run in 41:18 h as a whole) living on a raw vegan diet and having finished the competitions under these nutritional conditions. To this end, the vegan ultra triathlete and a control group of 10 Ironman triathletes of similar age living on a mixed diet were investigated, using echocardiography and spiroergometry. In addition, blood samples were taken from the vegan athlete both in the sporting season and in the off-season. The vegan athlete showed no signs of dietary deficiencies or impaired health. In comparison with the control group, the vegan athlete showed a higher oxygen intake at the respiratory compensation point. This case demonstrates that even top-class sporting performance, like that of a three-time Ironman, is possible on a vegan diet. Whether a vegan diet offers advantages or disadvantages for the performance of endurance athletes remains an open question. PMID:24826311

Assessment of upper-ocean variability and the Madden-Julian Oscillation in extended-range air-ocean coupled mesoscale simulations

NASA Astrophysics Data System (ADS)

Hong, Xiaodong; Reynolds, Carolyn A.; Doyle, James D.; May, Paul; O'Neill, Larry

2017-06-01

Atmosphere-ocean interaction, particular the ocean response to strong atmospheric forcing, is a fundamental component of the Madden-Julian Oscillation (MJO). In this paper, we examine how model errors in previous Madden-Julian Oscillation (MJO) events can affect the simulation of subsequent MJO events due to increased errors that develop in the upper-ocean before the MJO initiation stage. Two fully coupled numerical simulations with 45-km and 27-km horizontal resolutions were integrated for a two-month period from November to December 2011 using the Navy's limited area Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®). There are three MJO events that occurred subsequently in early November, mid-November, and mid-December during the simulations. The 45-km simulation shows an excessive warming of the SSTs during the suppressed phase that occurs before the initiation of the second MJO event due to erroneously strong surface net heat fluxes. The simulated second MJO event stalls over the Maritime Continent which prevents the recovery of the deep mixed layer and associated barrier layer. Cross-wavelet analysis of solar radiation and SSTs reveals that the diurnal warming is absent during the second suppressed phase after the second MJO event. The mixed layer heat budget indicates that the cooling is primarily caused by horizontal advection associated with the stalling of the second MJO event and the cool SSTs fail to initiate the third MJO event. When the horizontal resolution is increased to 27-km, three MJOs are simulated and compare well with observations on multi-month timescales. The higher-resolution simulation of the second MJO event and more-realistic upper-ocean response promote the onset of the third MJO event. Simulations performed with analyzed SSTs indicate that the stalling of the second MJO in the 45-km run is a robust feature, regardless of ocean forcing, while the diurnal cycle analysis indicates that both 45-km and 27-km ocean resolutions respond realistically when provided with realistic atmospheric forcing. Thus, the problem in the 45-km simulation appears to originate in the atmosphere. Additional simulations show that while the details of the simulations are sensitive to small changes in the initial integration time, the large differences between the 45-km and 27-km runs during the suppressed phase in early December are robust.

Factors affecting performance in an ultraendurance triathlon.

PubMed

Laursen, P B; Rhodes, E C

2001-01-01

In the recent past, researchers have found many key physiological variables that correlate highly with endurance performance. These include maximal oxygen uptake (VO2max), anaerobic threshold (AT), economy of motion and the fractional utilisation of oxygen uptake (VO2). However, beyond typical endurance events such as the marathon, termed 'ultraendurance' (i.e. >4 hours), performance becomes harder to predict. The ultraendurance triathlon (UET) is a 3-sport event consisting of a 3.8 km swim and a 180 km cycle, followed by a 42.2 km marathon run. It has been hypothesised that these triathletes ride at approximately their ventilatory threshold (Tvent) during the UET cycling phase. However, laboratory assessments of cycling time to exhaustion at a subject's AT peak at 255 minutes. This suggests that the AT is too great an intensity to be maintained during a UET, and that other factors cause detriments in prolonged performance. Potential defeating factors include the provision of fuels and fluids due to finite gastric emptying rates causing changes in substrate utilisation, as well as fluid and electrolyte imbalances. Thus, an optimum ultraendurance intensity that may be relative to the AT intensity is needed to establish ultraendurance intensity guidelines. This optimal UET intensity could be referred to as the ultraendurance threshold.

Abundance of adult saugers across the Wind River watershed, Wyoming

USGS Publications Warehouse

Amadio, C.J.; Hubert, W.A.; Johnson, K.; Oberlie, D.; Dufek, D.

2006-01-01

The abundance of adult saugers Sander canadensis was estimated over 179 km of continuous lotic habitat across a watershed on the western periphery of their natural distribution in Wyoming. Three-pass depletions with raft-mounted electrofishing gear were conducted in 283 pools and runs among 19 representative reaches totaling 51 km during the late summer and fall of 2002. From 2 to 239 saugers were estimated to occur among the 19 reaches of 1.6-3.8 km in length. The estimates were extrapolated to a total population estimate (mean ?? 95% confidence interval) of 4,115 ?? 308 adult saugers over 179 km of lotie habitat. Substantial variation in mean density (range = 1.0-32.5 fish/ha) and mean biomass (range = 0.5-16.8 kg/ha) of adult saugers in pools and runs was observed among the study reaches. Mean density and biomass were highest in river reaches with pools and runs that had maximum depths of more than 1 m, mean daily summer water temperatures exceeding 20??C, and alkalinity exceeding 130 mg/L. No saugers were captured in the 39 pools or runs with maximum water depths of 0.6 m or less. Multiple-regression analysis and the information-theoretic approach were used to identify watershed-scale and instream habitat features accounting for the variation in biomass among the 244 pools and runs across the watershed with maximum depths greater than 0.6 m. Sauger biomass was greater in pools than in runs and increased as mean daily summer water temperature, maximum depth, and mean summer alkalinity increased and as dominant substrate size decreased. This study provides an estimate of adult sauger abundance and identifies habitat features associated with variation in their density and biomass across a watershed, factors important to the management of both populations and habitat. ?? Copyright by the American Fisheries Society 2006.

Locomotion Mode Affects the Physiological Strain during Exercise at Walk-Run Transition Speed inElderly Men.

PubMed

Freire, Raul; Farinatti, Paulo; Cunha, Felipe; Silva, Brenno; Monteiro, Walace

2017-07-01

This study investigated cardiorespiratory responses and rating of perceived exertion (RPE) during prolonged walking and running exercise performed at the walk-run transition speed (WRTS) in untrained healthy elderly men. 20 volunteers (mean±SE, age: 68.4±1.2 yrs; height: 170.0±0.02 cm; body mass: 74.7±2.3 kg) performed the following bouts of exercise: a) maximal cardiopulmonary exercise test (CPET); b) specific protocol to detect WRTS; and c) two 30-min walking and running bouts at WRTS. Expired gases were collected during exercise bouts via the Ultima CardiO 2 metabolic analyzer. Compared to walking, running at the WRTS resulted in higher oxygen uptake (>0.27 L·min -1 ), pulmonary ventilation (>7.7 L·min -1 ), carbon dioxide output (>0.23 L·min -1 ), heart rate (>15 beats·min -1 ), oxygen pulse (>0.88 15 mL·beats -1 ), energy expenditure (>27 kcal) and cost of oxygen transport (>43 mL·kg -1 ·km -1 ·bout -1 ). The increase of overall and local RPEs with exercise duration was similar across locomotion modes (P<0.001). In all participants, %HRR and %VO 2 R throughout walking and running bouts were around or above the gas exchange threshold. In conclusion, elderly men exhibited higher cardiorespiratory responses during 30-min bouts of running than walking at WRTS. Nevertheless, walking corresponded to relative metabolic intensities compatible with preservation or improvement of cardiorespiratory fitness and should be preferable over running at WRTS in the untrained elderly characterized by poor fitness and reduced exercise tolerance. © Georg Thieme Verlag KG Stuttgart · New York.

Pacing profiles and pack running at the IAAF World Half Marathon Championships.

PubMed

Hanley, Brian

2015-01-01

The aim of this study was to describe the pacing profiles and packing behaviour of athletes competing in the IAAF World Half Marathon Championships. Finishing and split times were collated for 491 men and 347 women across six championships. The mean speeds for each intermediate 5 km and end 1.1 km segments were calculated, and athletes grouped according to finishing time. The best men and women largely maintained their split speeds between 5 km and 15 km, whereas slower athletes had decreased speeds from 5 km onwards. Athletes were also classified by the type of packing behaviour in which they engaged. Those who ran in packs throughout the race had smaller decreases in pace than those who did not, or who managed to do so only to 5 km. While some athletes' reduced speeds from 15 to 20 km might have been caused by fatigue, it was also possibly a tactic to aid a fast finish that was particularly beneficial to medallists. Those athletes who ran with the same competitors throughout sped up most during the finish. Athletes are advised to identify rivals likely to have similar abilities and ambitions and run with them as part of their pre-race strategy.

Altering Pace Control and Pace Regulation: Attentional Focus Effects during Running.

PubMed

Brick, Noel E; Campbell, Mark J; Metcalfe, Richard S; Mair, Jacqueline L; Macintyre, Tadhg E

2016-05-01

To date, there are no published studies directly comparing self-controlled (SC) and externally controlled (EC) pace endurance tasks. However, previous research suggests pace control may impact on cognitive strategy use and effort perceptions. The primary aim of this study was to investigate the effects of manipulating perception of pace control on attentional focus, physiological, and psychological outcomes during running. The secondary aim was to determine the reproducibility of self-paced running performance when regulated by effort perceptions. Twenty experienced endurance runners completed four 3-km time trials on a treadmill. Subjects completed two SC pace trials, one perceived exertion clamped (PE) trial, and one EC pace time trial. PE and EC were completed in a counterbalanced order. Pacing strategy for EC and perceived exertion instructions for PE replicated the subjects' fastest SC time trial. Subjects reported a greater focus on cognitive strategies such as relaxing and optimizing running action during EC than during SC. The mean HR was 2% lower during EC than that during SC despite an identical pacing strategy. Perceived exertion did not differ between the three conditions. However, increased internal sensory monitoring coincided with elevated effort perceptions in some subjects during EC and a 10% slower completion time for PE (13.0 ± 1.6 min) than that for SC (11.8 ± 1.2 min). Altering pace control and pace regulation impacted on attentional focus. External control over pacing may facilitate performance, particularly when runners engage attentional strategies conducive to improved running efficiency. However, regulating pace based on effort perceptions alone may result in excessive monitoring of bodily sensations and a slower running speed. Accordingly, attentional focus interventions may prove beneficial for some athletes to adopt task-appropriate attentional strategies to optimize performance.

Evaluation of WRF Parameterizations for Air Quality Applications over the Midwest USA

NASA Astrophysics Data System (ADS)

Zheng, Z.; Fu, K.; Balasubramanian, S.; Koloutsou-Vakakis, S.; McFarland, D. M.; Rood, M. J.

2017-12-01

Reliable predictions from Chemical Transport Models (CTMs) for air quality research require accurate gridded weather inputs. In this study, a sensitivity analysis of 17 Weather Research and Forecast (WRF) model runs was conducted to explore the optimum configuration in six physics categories (i.e., cumulus, surface layer, microphysics, land surface model, planetary boundary layer, and longwave/shortwave radiation) for the Midwest USA. WRF runs were initally conducted over four days in May 2011 for a 12 km x 12 km domain over contiguous USA and a nested 4 km x 4 km domain over the Midwest USA (i.e., Illinois and adjacent areas including Iowa, Indiana, and Missouri). Model outputs were evaluated statistically by comparison with meteorological observations (DS337.0, METAR data, and the Water and Atmospheric Resources Monitoring Network) and resulting statistics were compared to benchmark values from the literature. Identified optimum configurations of physics parametrizations were then evaluated for the whole months of May and October 2011 to evaluate WRF model performance for Midwestern spring and fall seasons. This study demonstrated that for the chosen physics options, WRF predicted well temperature (Index of Agreement (IOA) = 0.99), pressure (IOA = 0.99), relative humidity (IOA = 0.93), wind speed (IOA = 0.85), and wind direction (IOA = 0.97). However, WRF did not predict daily precipitation satisfactorily (IOA = 0.16). Developed gridded weather fields will be used as inputs to a CTM ensemble consisting of the Comprehensive Air Quality Model with Extensions to study impacts of chemical fertilizer usage on regional air quality in the Midwest USA.

Serum Oxidant and Antioxidant Status Following an All-Out 21-km Run in Adolescent Runners Undergoing Professional Training—A One-Year Prospective Trial

PubMed Central

Tong, Tom K.; Kong, Zhaowei; Lin, Hua; Lippi, Giuseppe; Zhang, Haifeng; Nie, Jinlei

2013-01-01

This study investigated the 1-year longitudinal effect of professional training in adolescent runners on redox balance during intense endurance exercise. Changes in selected serum oxidant and antioxidant status in response to a 21-km running time trial in 10 runners (15.5 ± 1.3 years) undergoing professional training were evaluated twice in 12 months (pre- and post-evaluation). Venous blood samples were collected immediately before and 4-h following the 21-km run for analysis of serum concentrations of thiobarbituric acid-reactive substances (TBARS), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC). In pre-evaluation trial, serum TBARS and SOD decreased after the 21-km run (p < 0.05) while XO, GSH, CAT and TAOC were unchanged. In post-evaluation trial, serum TBARS and SOD decreased, whereas XO and CAT increased post-exercise (p < 0.05). Furthermore, pre-exercise serum T-AOC, post-exercise serum XO, CAT, T-AOC (p < 0.05), and GSH (p = 0.057) appeared to be higher than the corresponding pre-evaluation values. The current findings suggest that a professional training regime in adolescent runners is not likely to jeopardize the development of their antioxidant defense. However, uncertainties in the maintenance of redox balance in runners facing increased exercise-induced oxidative stress as a consequence of training-induced enhancement of exercise capacity await further elucidation. PMID:23880864

The cost of transport of human running is not affected, as in walking, by wide acceleration/deceleration cycles.

PubMed

Minetti, Alberto E; Gaudino, Paolo; Seminati, Elena; Cazzola, Dario

2013-02-15

Although most of the literature on locomotion energetics and biomechanics is about constant-speed experiments, humans and animals tend to move at variable speeds in their daily life. This study addresses the following questions: 1) how much extra metabolic energy is associated with traveling a unit distance by adopting acceleration/deceleration cycles in walking and running, with respect to constant speed, and 2) how can biomechanics explain those metabolic findings. Ten males and ten females walked and ran at fluctuating speeds (5 ± 0, ± 1, ± 1.5, ± 2, ± 2.5 km/h for treadmill walking, 11 ± 0, ± 1, ± 2, ± 3, ± 4 km/h for treadmill and field running) in cycles lasting 6 s. Field experiments, consisting of subjects following a laser spot projected from a computer-controlled astronomic telescope, were necessary to check the noninertial bias of the oscillating-speed treadmill. Metabolic cost of transport was found to be almost constant at all speed oscillations for running and up to ±2 km/h for walking, with no remarkable differences between laboratory and field results. The substantial constancy of the metabolic cost is not explained by the predicted cost of pure acceleration/deceleration. As for walking, results from speed-oscillation running suggest that the inherent within-stride, elastic energy-free accelerations/decelerations when moving at constant speed work as a mechanical buffer for among-stride speed fluctuations, with no extra metabolic cost. Also, a recent theory about the analogy between sprint (level) running and constant-speed running on gradients, together with the mechanical determinants of gradient locomotion, helps to interpret the present findings.

Right ventricle best predicts the race performance in amateur ironman athletes.

PubMed

Bernheim, Alain Marcel; Attenhofer Jost, Christine Helena; Zuber, Michel; Pfyffer, Monica; Seifert, Burkhardt; De Pasquale, Gabriella; Linka, Andre; Faeh-Gunz, Anja; Medeiros-Domingo, Argelia; Knechtle, Beat

2013-08-01

The ironman (IM) triathlon is a popular ultraendurance competition, consisting of 3.8 km of swimming, 180.2 km of cycling, and 42.2 km of running. The aim of this study was to investigate the predictors of IM race time, comparing echocardiographic findings, anthropometric measures, and training characteristics. Amateur IM athletes (ATHL) participating in the Zurich IM race in 2010 were included. Participants were examined the day before the race by a comprehensive echocardiographic examination. Moreover, anthropometric measurements were obtained the same day. During the 3 months before the race, each IM-ATHL maintained a detailed training diary. Recorded data were related to total IM race time. Thirty-eight IM finishers (mean ± SD age = 38 ± 9 yr, 32 men [84%]) were evaluated. Total race time was 684 ± 89 min (mean ± SD). For right ventricular fractional area change (45% ± 7%, Spearman ρ = -0.33, P = 0.05), a weak correlation with race time was observed. Race performance exhibited stronger associations with percent body fat (15.2 ± 5.6%, ρ = 0.56, P = 0.001), speed in running training (11.7 ± 1.2 km · h(-1), ρ = -0.52, P = 0.002), and left ventricular myocardial mass index (98 ± 24 g · m(-2), ρ = -0.42, P = 0.009). The strongest association was found between race time and right ventricular end-diastolic area (22 ± 4 cm2, ρ = -0.64, P < 0.0001). In multivariate analysis, right ventricular end-diastolic area (β = -16.7, 95% confidence interval = -27.3 to -6.1, P = 0.003) and percent body fat (β = 6.8, 95% confidence interval = 1.1-12.6, P = 0.02) were independently predictive of IM race time. In amateur IM-ATHL, RV end-diastolic area and percent body fat were independently related to race performance. RV end-diastolic area was the strongest predictor of race time. The role of the RV in endurance exercise may thus be more important than previously thought and needs to be further studied.

Lactate-related factors as a critical determinant of endurance.

PubMed

Tanaka, K

1990-04-01

Many interrelated physiological and/or morphological factors have been demonstrated to influence endurance exercise performance. Some of these factors include skeletal musculature, running economy, maximal oxygen uptake (VO2max), maximal steady state (MSS), onset of blood lactate accumulation (OBLA), onset of plasma lactate accumulation (OPLA), and anaerobic (or lactate) threshold (AT or LT). The present paper focuses mainly on VO2max, MSS, OBLA, OPLA and LT, all of which have been postulated as a prerequisite in endurance exercise success. This paper consists of: (1) significance of La-related variables, (2) longitudinal studies, (3) comments, and (4) conclusion. Briefly, it is suggested that estimation of endurance exercise potential could be obtained with relatively high precision using laboratoriously measured La-related variables. The most critical determinant of endurance exercise performance such as marathon time is considered running velocity (V) at which LT is detected (V / LT), VO2 / LT, or V / MSS, while V / OBLA appears to be the best predictor of performance in endurance events of 16 km or shorter distances.

Evaluations of high-resolution dynamically downscaled ensembles over the contiguous United States

NASA Astrophysics Data System (ADS)

Zobel, Zachary; Wang, Jiali; Wuebbles, Donald J.; Kotamarthi, V. Rao

2018-02-01

This study uses Weather Research and Forecast (WRF) model to evaluate the performance of six dynamical downscaled decadal historical simulations with 12-km resolution for a large domain (7200 × 6180 km) that covers most of North America. The initial and boundary conditions are from three global climate models (GCMs) and one reanalysis data. The GCMs employed in this study are the Geophysical Fluid Dynamics Laboratory Earth System Model with Generalized Ocean Layer Dynamics component, Community Climate System Model, version 4, and the Hadley Centre Global Environment Model, version 2-Earth System. The reanalysis data is from the National Centers for Environmental Prediction-US. Department of Energy Reanalysis II. We analyze the effects of bias correcting, the lateral boundary conditions and the effects of spectral nudging. We evaluate the model performance for seven surface variables and four upper atmospheric variables based on their climatology and extremes for seven subregions across the United States. The results indicate that the simulation's performance depends on both location and the features/variable being tested. We find that the use of bias correction and/or nudging is beneficial in many situations, but employing these when running the RCM is not always an improvement when compared to the reference data. The use of an ensemble mean and median leads to a better performance in measuring the climatology, while it is significantly biased for the extremes, showing much larger differences than individual GCM driven model simulations from the reference data. This study provides a comprehensive evaluation of these historical model runs in order to make informed decisions when making future projections.

Repeated-sprint ability and team selection in Australian football league players.

PubMed

Le Rossignol, Peter; Gabbett, Tim J; Comerford, Dan; Stanton, Warren R

2014-01-01

To investigate the relationship between selected physical capacities and repeated-sprint performance of Australian Football League (AFL) players and to determine which physical capacities contributed to being selected for the first competition game. Sum of skinfolds, 40-m sprint (with 10-, 20-, 30-, and 40-m splits), repeated-sprint ability (6 × 30-m sprints), and 3-km-run time were measured during the preseason in 20 AFL players. The physical qualities of players selected to play the first match of the season and those not selected were compared. Pearson correlation coefficients were used to determine the relationship among variables, and a regression analysis identified variables significantly related to repeated-sprint performance. In the regression analysis, maximum velocity was the best predictor of repeated-sprint time, with 3-km-run time also contributing significantly to the predictive model. Sum of skinfolds was significantly correlated with 10-m (r = .61, P < .01) and 30-m (r = .53, P < .05) sprint times. A 2.6% ± 2.1% difference in repeated-sprint time (P < .05, ES = 0.88 ± 0.72) was observed between those selected (25.26 ± 0.55 s) and not selected (25.82 ± 0.80 s) for the first game of the season. The findings indicate that maximum-velocity training using intervals of 30-40 m may contribute more to improving repeated-sprint performance in AFL players than short 10- to 20-m intervals from standing starts. Further research is warranted to establish the relative importance of endurance training for improving repeated-sprint performance in AFL football.

Foot strike patterns of recreational and sub-elite runners in a long-distance road race.

PubMed

Larson, Peter; Higgins, Erin; Kaminski, Justin; Decker, Tamara; Preble, Janine; Lyons, Daniela; McIntyre, Kevin; Normile, Adam

2011-12-01

Although the biomechanical properties of the various types of running foot strike (rearfoot, midfoot, and forefoot) have been studied extensively in the laboratory, only a few studies have attempted to quantify the frequency of running foot strike variants among runners in competitive road races. We classified the left and right foot strike patterns of 936 distance runners, most of whom would be considered of recreational or sub-elite ability, at the 10 km point of a half-marathon/marathon road race. We classified 88.9% of runners at the 10 km point as rearfoot strikers, 3.4% as midfoot strikers, 1.8% as forefoot strikers, and 5.9% of runners exhibited discrete foot strike asymmetry. Rearfoot striking was more common among our sample of mostly recreational distance runners than has been previously reported for samples of faster runners. We also compared foot strike patterns of 286 individual marathon runners between the 10 km and 32 km race locations and observed increased frequency of rearfoot striking at 32 km. A large percentage of runners switched from midfoot and forefoot foot strikes at 10 km to rearfoot strikes at 32 km. The frequency of discrete foot strike asymmetry declined from the 10 km to the 32 km location. Among marathon runners, we found no significant relationship between foot strike patterns and race times.

The Impact of TRMM on Mesoscale Model Simulation of Super Typhoon Paka

NASA Technical Reports Server (NTRS)

Tao, W.-K.; Jia, Y.; Halverson, J.; Hou, A.; Olson, W.; Rodgers, E.; Simpson, J.

1999-01-01

Tropical cyclone Paka formed during the first week of December 1997 and underwent three periods of rapid intensification over the following two weeks. During one of these periods, which initiated early on December 10, Paka's Dvorak-measured windspeed increased from 23 to 60 m/s over a 48-hr period. On December 18, during the last rapid deepening episode, Paka became a supertyphoon with a maximum wind speed of about 80 m/s. In this study, the Penn State/NCAR Mesoscale Model (MM5) with improved physics (i.e., cloud microphysics, radiation, land-soil-vegetation-surface processes, and TOGA COARE flux scheme) and a multiple level nesting technique (135, 45 and 15 km horizontal resolution) will be used to simulate supertyphoon Paka. We performed two runs initialized with Goddard Earth Observing System (GEOS) data sets. The first GEOS data set does not incorporate either TRMM (tropical rainfall measuring mission satellite) or SSM/I (sensor microwave imager) observed rainfall fields into the GEOS's assimilation system while the second one does. Preliminary results show that the MM5 simulated surface pressure deepened by more than 25 mb (45 km resolution domain) in the run initialized with the GEOS data set incorporating TRMM and SSM/I derived rainfall, compared to the one initialized without. However, the track and precipitation patterns are quite similar between the runs. In our presentation, we will show the impact of TRMM rainfall upon the MM5 simulation of Paka at various horizontal resolutions. We will also examine the physical processes associated with initial explosive development by comparing MM5 simulated rainfall and latent heat release. In addition, budget (vorticity, PV, momentum and heat) calculations and sensitivity tests will be performed to examine the upper-tropospheric and SST mechanisms responsible for the explosive development of Paka.

Analysis of the August and November dynamical structures in the MLT region

NASA Astrophysics Data System (ADS)

Gusev, O.; Grossmann, K.-U.; Schmidt, H.

The inversion of the infrared limb radiance measurements made by {CR}yogenic {I}nfrared {S}pectrometers and {T}elescopes for the {A}tmosphere (CRISTA) satellite experiment provided a global dataset of pressures, temperatures and atmospheric gas number densities for November 1994 and August 1997 in the altitude range 7-180 km. The {HAM}burg {MO}del of the {N}eutral and {I}onized {A}tmosphere (HAMMONIA) is a general circulation and chemistry model covering the atmosphere from the Earth's surface up to about 250 km. To simulate the conditions found during both CRISTA time periods a special HAMMONIA run was performed. We discuss the MLT dynamical parameters found by analysing the measured and modelled data, their similarities and differences.

A Comparison of Mixed-Method Cooling Interventions on Preloaded Running Performance in the Heat.

PubMed

Stevens, Christopher J; Bennett, Kyle J M; Sculley, Dean V; Callister, Robin; Taylor, Lee; Dascombe, Ben J

2017-03-01

Stevens, CJ, Bennett, KJM, Sculley, DV, Callister, R, Taylor, L, and Dascombe, BJ. A comparison of mixed-method cooling interventions on preloaded running performance in the heat. J Strength Cond Res 31(3): 620-629, 2017-The purpose of this investigation was to assess the effect of combining practical methods to cool the body on endurance running performance and physiology in the heat. Eleven trained male runners completed 4 randomized, preloaded running time trials (20 minutes at 70% V[Combining Dot Above]O2max and a 3 km time trial) on a nonmotorized treadmill in the heat (33° C). Trials consisted of precooling by combined cold-water immersion and ice slurry ingestion (PRE), midcooling by combined facial water spray and menthol mouth rinse (MID), a combination of all methods (ALL), and control (CON). Performance time was significantly faster in MID (13.7 ± 1.2 minutes; p < 0.01) and ALL (13.7 ± 1.4 minutes; p = 0.04) but not PRE (13.9 ± 1.4 minutes; p = 0.24) when compared with CON (14.2 ± 1.2 minutes). Precooling significantly reduced rectal temperature (initially by 0.5 ± 0.2° C), mean skin temperature, heart rate and sweat rate, and increased iEMG activity, whereas midcooling significantly increased expired air volume and respiratory exchange ratio compared with control. Significant decreases in forehead temperature, thermal sensation, and postexercise blood prolactin concentration were observed in all conditions compared with control. Performance was improved with midcooling, whereas precooling had little or no influence. Midcooling may have improved performance through an attenuated inhibitory psychophysiological and endocrine response to the heat.

App use, physical activity and healthy lifestyle: a cross sectional study.

PubMed

Dallinga, Joan Martine; Mennes, Matthijs; Alpay, Laurence; Bijwaard, Harmen; Baart de la Faille-Deutekom, Marije

2015-08-28

Physical inactivity is a growing public health concern. Use of mobile applications (apps) may be a powerful tool to encourage physical activity and a healthy lifestyle. For instance, apps may be used in the preparation of a running event. However, there is little evidence for the relationship between app use and change in physical activity and health in recreational runners. The aim of this study was to determine the relationship between the use of apps and changes in physical activity, health and lifestyle behaviour, and self-image of short and long distance runners. A cross sectional study was designed. A random selection of 15,000 runners (of 54,000 participants) of a 16 and 6.4 km recreational run (Dam tot Damloop) in the Netherlands was invited to participate in an online survey two days after the run. Anthropometrics, app use, activity level, preparation for running event, running physical activity (RPA), health and lifestyle, and self-image were addressed. A chi-squared test was conducted to analyse differences between app users and non-app users in baseline characteristics as well as in RPA, healthy lifestyle and perceived health. In addition, a multivariate logistic regression analysis was performed to determine if app use could predict RPA, perceived health and lifestyle, and self-image. Of the 15,000 invited runners, 28% responded. For both distances, app use was positively related to RPA and feeling healthier (p < 0.05). Also, app use was positively related to feeling better about themselves, feeling like an athlete, motivating others to participate in running, and losing weight (p < 0.01). Furthermore, for 16 km runners app use was positively related to eating healthier, feeling more energetic and reporting a higher chance to maintain sport behaviour (p < 0.05). These results suggest that use of mobile apps has a beneficial role in the preparation of a running event, as it promotes health and physical activity. Further research is now needed to determine a causal relationship between app use and physical and health related behaviour.

Hindcasting the Madden‐Julian Oscillation With a New Parameterization of Surface Heat Fluxes

PubMed Central

Wang, Jingfeng; Lin, Wenshi

2017-01-01

Abstract The recently developed maximum entropy production (MEP) model, an alternative parameterization of surface heat fluxes, is incorporated into the Weather Research and Forecasting (WRF) model. A pair of WRF cloud‐resolving experiments (5 km grids) using the bulk transfer model (WRF default) and the MEP model of surface heat fluxes are performed to hindcast the October Madden‐Julian oscillation (MJO) event observed during the 2011 Dynamics of the MJO (DYNAMO) field campaign. The simulated surface latent and sensible heat fluxes in the MEP and bulk transfer model runs are in general consistent with in situ observations from two research vessels. Compared to the bulk transfer model, the convection envelope is strengthened in the MEP run and shows a more coherent propagation over the Maritime Continent. The simulated precipitable water in the MEP run is in closer agreement with the observations. Precipitation in the MEP run is enhanced during the active phase of the MJO with significantly reduced regional dry and wet biases. Large‐scale ocean evaporation is stronger in the MEP run leading to stronger boundary layer moistening to the east of the convection center, which facilitates the eastward propagation of the MJO. PMID:29399269

Run Economy on a Normal and Lower Body Positive Pressure Treadmill.

PubMed

Temple, Corey; Lind, Erik; VAN Langen, Deborah; True, Larissa; Hupman, Saige; Hokanson, James F

2017-01-01

Lower body positive pressure (LBPP) treadmill running is used more frequently in clinical and athletic settings. Accurate caloric expenditure is required for proper exercise prescription, especially for obese patients performing LBPP exercise. It is unclear if running on LBPP changes running economy (RE) in proportion to the changes in body weight. The purpose of the study was to measure the oxygen consumption (VO 2 ) and running economy (RE) of treadmill running at normal body weight and on LBPP. Twenty-three active, non-obese participants (25.8±7.2 years; BMI = 25.52±3.29 kg·m -2 ) completed two bouts of running exercise in a counterbalanced manner: (a) on a normal treadmill (NT) and (b) on a LBPP treadmill at 60% (40% of body weight supported) for 4 min at 2.24 (5 mph), 2.68 (6 mph), and 3.13 m·s -1 (7 mph). Repeated measures ANOVA showed a statistically significant interaction in RE among trials, F(2, 44) = 6.510, p <.0005, partial η 2 = 0.228. An examination of pairwise comparisons indicated that RE was significantly greater for LBPP across the three speeds ( p < 0.005). As expected, LBPP treadmill running resulted in significantly lower oxygen consumption at all three running speeds. We conclude that RE (ml O 2 ·kg -1 ·km -1 ) of LBPP running is significantly poorer than normal treadmill running, and the ~30% change in absolute energy cost is not as great as predicted by the change in body weight (40%).

The Met Office Coupled Atmosphere/Land/Ocean/Sea-Ice Data Assimilation System

NASA Astrophysics Data System (ADS)

Lea, Daniel; Mirouze, Isabelle; King, Robert; Martin, Matthew; Hines, Adrian

2015-04-01

The Met Office has developed a weakly-coupled data assimilation (DA) system using the global coupled model HadGEM3 (Hadley Centre Global Environment Model, version 3). At present the analysis from separate ocean and atmosphere DA systems are combined to produced coupled forecasts. The aim of coupled DA is to produce a more consistent analysis for coupled forecasts which may lead to less initialisation shock and improved forecast performance. The HadGEM3 coupled model combines the atmospheric model UM (Unified Model) at 60 km horizontal resolution on 85 vertical levels, the ocean model NEMO (Nucleus for European Modelling of the Ocean) at 25 km (at the equator) horizontal resolution on 75 vertical levels, and the sea-ice model CICE at the same resolution as NEMO. The atmosphere and the ocean/sea-ice fields are coupled every 1-hour using the OASIS coupler. The coupled model is corrected using two separate 6-hour window data assimilation systems: a 4D-Var for the atmosphere with associated soil moisture content nudging and snow analysis schemes on the one hand, and a 3D-Var FGAT for the ocean and sea-ice on the other hand. The background information in the DA systems comes from a previous 6-hour forecast of the coupled model. To isolate the impact of the coupled DA, 13-month experiments have been carried out, including 1) a full atmosphere/land/ocean/sea-ice coupled DA run, 2) an atmosphere-only run forced by OSTIA SSTs and sea-ice with atmosphere and land DA, and 3) an ocean-only run forced by atmospheric fields from run 2 with ocean and sea-ice DA. In addition, 5-day and 10-day forecast runs, have been produced from initial conditions generated by either run 1 or a combination of runs 2 and 3. The different results have been compared to each other and, whenever possible, to other references such as the Met Office atmosphere and ocean operational analyses or the OSTIA SST data. The performance of the coupled DA is similar to the existing separate ocean and atmosphere DA systems. This is despite the fact that the assimilation error covariances have not yet been tuned for coupled DA. In addition, the coupled model also exhibits some biases which do not affect the uncoupled models. An example is precipitation and run off errors affecting the ocean salinity. This of course impacts the performance of the ocean data assimilation. This does, however, highlight a particular benefit of data assimilation in that it can help to identify short term model biases by using, for example, the differences between the observations and model background (innovations) and the mean increments. Coupled DA has the distinct advantage that this gives direct information about the coupled model short term biases. By identifying the biases and developing solutions this will improve the short range coupled forecasts, and may also improve the coupled model on climate timescales.

Near-field survey of the 1946 Aleutian tsunami on Unimak and Sanak Islands

USGS Publications Warehouse

Okal, E.A.; Plafker, G.; Synolakis, C.E.; Borrero, J.C.

2003-01-01

The 1946 Aleutian earthquake stands out among tsunamigenic events because it generated both very high run-up near the earthquake source region and a destructive trans-Pacific tsunami. We obtained new data on the distribution of its tsunami in the near field along south-facing coasts between Unimak Pass on the west and Sanak Island on the east by measuring the height of driftwood and beach materials that were deposited by the tsunami above the extreme storm tide level. Our data indicate that (1) the highest measured run-up, which is at the Scotch Cap lighthouse, was 42 m above tide level or about 37 m above present storm tide elevation; (2) run-up along the rugged coast from Scotch Cap for 12 km northwest to Sennett Point is 12-18 m, and for 30 km east of Scotch Cap to Cape Lutke it is 24-42 m; (3) run-up along the broad lowlands bordering Unimak Bight is 10-20 m, and in-undation is locally more than 2 km; (5) run-up diminishes to 8 m or less at the southeast corner of Unimak Island; (6) no evidence was found for run-up above present storm tides (about 4-5 m above MLLW) on the Ikatan Peninsula or areas along the coast to the west; and (7) run-up above storm tide level in the Sanak Island group is restricted to southwest-facing coasts of Sanak, Long, and Clifford Islands, where it is continuous and locally up to 24 m high. Generation of the tsunami by one or more major earthquake-triggered submarine landslides near the shelf edge south of Unimak Island seems to be the only viable mechanism to account for the data on wave arrival time, run-up heights, and distribution, as well as for unconfirmed anecdotal reports of local postquake increases in water depth and diminished bottom-fisheries productivity. A preliminary hydrodynamic simulation of the local tsunami propagation and run-up using a dipolar model of a possible landslide off Davidson Bank provides an acceptable fit to the characteristics of the distribution of local run-up, with a value at 34 m at the Scotch Cap lighthouse.

NASA evaluation of Type 2 chemical depositions. [effects of deicer deposition on aircraft tire friction performance

NASA Technical Reports Server (NTRS)

Yager, Thomas J.; Stubbs, Sandy M.; Howell, W. Edward; Webb, Granville L.

1993-01-01

Recent findings from NASA Langley tests to define effects of aircraft Type 2 chemical deicer depositions on aircraft tire friction performance are summarized. The Aircraft Landing Dynamics Facility (ALDF) is described together with the scope of the tire cornering and braking friction tests conducted up to 160 knots ground speed. Some lower speed 32 - 96 km/hr (20 - 60 mph) test run data obtained using an Instrumented Tire Test Vehicle (ITTV) to determine effects of tire bearing pressure and transverse grooving on cornering friction performance are also discussed. Recommendations are made concerning which parameters should be evaluated in future testing.

Nighttime feeding likely alters morning metabolism but not exercise performance in female athletes.

PubMed

Ormsbee, Michael J; Gorman, Katherine A; Miller, Elizabeth A; Baur, Daniel A; Eckel, Lisa A; Contreras, Robert J; Panton, Lynn B; Spicer, Maria T

2016-07-01

The timing of morning endurance competition may limit proper pre-race fueling and resulting performance. A nighttime, pre-sleep nutritional strategy could be an alternative method to target the metabolic and hydrating needs of the early morning athlete without compromising sleep or gastrointestinal comfort during exercise. Therefore, the purpose of this investigation was to examine the acute effects of pre-sleep chocolate milk (CM) ingestion on next-morning running performance, metabolism, and hydration status. Twelve competitive female runners and triathletes (age, 30 ± 7 years; peak oxygen consumption, 53 ± 4 mL·kg(-1)·min(-1)) randomly ingested either pre-sleep CM or non-nutritive placebo (PL) ∼30 min before sleep and 7-9 h before a morning exercise trial. Resting metabolic rate (RMR) was assessed prior to exercise. The exercise trial included a warm-up, three 5-min incremental workloads at 55%, 65%, and 75% peak oxygen consumption, and a 10-km treadmill time trial (TT). Physiological responses were assessed prior, during (incremental and TT), and postexercise. Paired t tests and magnitude-based inferences were used to determine treatment differences. TT performances were not different ("most likely trivial" improvement with CM) between conditions (PL: 52.8 ± 8.4 min vs CM: 52.8 ± 8.0 min). RMR was "likely" increased (4.8%) and total carbohydrate oxidation (g·min(-1)) during exercise was "possibly" or likely increased (18.8%, 10.1%, 9.1% for stage 1-3, respectively) with CM versus PL. There were no consistent changes to hydration indices. In conclusion, pre-sleep CM may alter next-morning resting and exercise metabolism to favor carbohydrate oxidation, but effects did not translate to 10-km running performance improvements.

Carbohydrate Intake in Form of Gel Is Associated With Increased Gastrointestinal Distress but Not With Performance Differences Compared With Liquid Carbohydrate Ingestion During Simulated Long-Distance Triathlon.

PubMed

Sareban, Mahdi; Zügel, David; Koehler, Karsten; Hartveg, Paul; Zügel, Martina; Schumann, Uwe; Steinacker, Jürgen Michael; Treff, Gunnar

2016-04-01

The ingestion of exogenous carbohydrates (CHO) during prolonged endurance exercise, such as long-distance triathlon, is considered beneficial with regard to performance. However, little is known about whether this performance benefit differs among different forms of CHO administration. To this end, the purpose of our study was to determine the impact of CHO ingestion from a semisolid source (GEL) on measures of performance and gastrointestinal (GI) comfort compared with CHO ingestion from a liquid source (LIQ). Nine well-trained triathletes participated in this randomized crossover study. Each participant completed a 60-min swim, 180-min bike exercise, and a 60-min all-out run in a laboratory environment under 2 conditions, once while receiving 67.2 ± 7.2 g · h-1 (M ± SD) of CHO from GEL and once while receiving 67.8 ± 4.2 g · h-1 of CHO from LIQ. The amount of fluid provided was matched among conditions. Respiratory exchange ratio (RER), blood glucose, and lactate as well as GI discomfort were assessed at regular intervals during the experiment. The distance covered during the final all-out run was not significantly different among participants ingesting GEL (11.81 ± 1.38 km) and LIQ (11.91 ± 1.53 km; p = .89). RER, blood glucose, and lactate did not differ significantly at any time during the experiment. Seven participants reported GI discomfort with GEL, and no athlete reported GI discomfort with LIQ (p = .016). This study suggests that administration of GEL does not alter long-distance triathlon performance when compared with LIQ, but GEL seems to be associated with reduced GI tolerance. Athletes should consider this a potential disadvantage of GEL administration during long-distance triathlon.

The correlation between running economy and maximal oxygen uptake: cross-sectional and longitudinal relationships in highly trained distance runners.

PubMed

Shaw, Andrew J; Ingham, Stephen A; Atkinson, Greg; Folland, Jonathan P

2015-01-01

A positive relationship between running economy and maximal oxygen uptake (V̇O2max) has been postulated in trained athletes, but previous evidence is equivocal and could have been confounded by statistical artefacts. Whether this relationship is preserved in response to running training (changes in running economy and V̇O2max) has yet to be explored. This study examined the relationships of (i) running economy and V̇O2max between runners, and (ii) the changes in running economy and V̇O2max that occur within runners in response to habitual training. 168 trained distance runners (males, n = 98, V̇O2max 73.0 ± 6.3 mL∙kg-1∙min-1; females, n = 70, V̇O2max 65.2 ± 5.9 mL kg-1∙min-1) performed a discontinuous submaximal running test to determine running economy (kcal∙km-1). A continuous incremental treadmill running test to volitional exhaustion was used to determine V̇O2max 54 participants (males, n = 27; females, n = 27) also completed at least one follow up assessment. Partial correlation analysis revealed small positive relationships between running economy and V̇O2max (males r = 0.26, females r = 0.25; P<0.006), in addition to moderate positive relationships between the changes in running economy and V̇O2max in response to habitual training (r = 0.35; P<0.001). In conclusion, the current investigation demonstrates that only a small to moderate relationship exists between running economy and V̇O2max in highly trained distance runners. With >85% of the variance in these parameters unexplained by this relationship, these findings reaffirm that running economy and V̇O2max are primarily determined independently.

The long-term effect of minimalist shoes on running performance and injury: design of a randomised controlled trial.

PubMed

Fuller, Joel T; Thewlis, Dominic; Tsiros, Margarita D; Brown, Nicholas A T; Buckley, Jonathan D

2015-08-21

The outcome of the effects of transitioning to minimalist running shoes is a topic of interest for runners and scientists. However, few studies have investigated the longer term effects of running in minimalist shoes. The purpose of this randomised controlled trial (RCT) is to investigate the effects of a 26 week transition to minimalist shoes on running performance and injury risk in trained runners unaccustomed to minimalist footwear. A randomised parallel intervention design will be used. Seventy-six trained male runners will be recruited. To be eligible, runners must be aged 18-40 years, run with a habitual rearfoot footfall pattern, train with conventional shoes and have no prior experience with minimalist shoes. Runners will complete a standardised transition to either minimalist or control shoes and undergo assessments at baseline, 6 and 26 weeks. 5 km time-trial performance (5TT), running economy, running biomechanics, triceps surae muscle strength and lower limb bone mineral density will be assessed at each time point. Pain and injury will be recorded weekly. Training will be standardised during the first 6 weeks. Primary statistical analysis will compare 5TT between shoe groups at the 6-week time point and injury incidence across the entire 26-week study period. This RCT has been approved by the Human Research Ethics Committee of the University of South Australia. Participants will be required to provide their written informed consent prior to participation in the study. Study findings will be disseminated in the form of journal publications and conference presentations after completion of planned data analysis. This RCT has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN12613000642785). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Coordinate and synergistic effects of extensive treadmill exercise and ovariectomy on articular cartilage degeneration.

PubMed

Miyatake, Kazumasa; Muneta, Takeshi; Ojima, Miyoko; Yamada, Jun; Matsukura, Yu; Abula, Kahaer; Sekiya, Ichiro; Tsuji, Kunikazu

2016-05-31

Although osteoarthritis (OA) is a multifactorial disease, little has been reported regarding the cooperative interaction among these factors on cartilage metabolism. Here we examined the synergistic effect of ovariectomy (OVX) and excessive mechanical stress (forced running) on articular cartilage homeostasis in a mouse model resembling a human postmenopausal condition. Mice were randomly divided into four groups, I: Sham, II: OVX, III: Sham and forced running (60 km in 6 weeks), and IV: OVX and forced running. Histological and immunohistochemical analyses were performed to evaluate the degeneration of articular cartilage and synovitis in the knee joint. Morphological changes of subchondral bone were analyzed by micro-CT. Micro-CT analyses showed significant loss of metaphyseal trabecular bone volume/tissue volume (BV/TV) after OVX as described previously. Forced running increased the trabecular BV/TV in all mice. In the epiphyseal region, no visible alteration in bone morphology or osteophyte formation was observed in any of the four groups. Histological analysis revealed that OVX or forced running respectively had subtle effects on cartilage degeneration. However, the combination of OVX and forced running synergistically enhanced synovitis and articular cartilage degeneration. Although morphological changes in chondrocytes were observed during OA initiation, no signs of bone marrow edema were observed in any of the four experimental groups. We report the coordinate and synergistic effects of extensive treadmill exercise and ovariectomy on articular cartilage degeneration. Since no surgical procedure was performed on the knee joint directly in this model, this model is useful in addressing the molecular pathogenesis of naturally occurring OA.

Polycyclic aromatic hydrocarbons, elemental and organic carbon emissions from tire-wear.

PubMed

Aatmeeyata; Sharma, Mukesh

2010-09-15

Tire-wear is an important source of PAHs, elemental carbon (EC) and organic carbon (OC). The emissions of these pollutants have been studied in an experimental set-up, simulating a realistic road-tire interaction (summer tire-concrete road). The large particle non-exhaust emissions (LPNE; diameter greater than 10 microm) have been evaluated over 14,500 km run of the tire. An increasing linear trend with cumulative km run was observed for emissions of PAHs and carbon. Amongst PAHs in LPNE, pyrene has been observed to be the highest (30+/-4 mg kg(-1)) followed by benzo[ghi]perylene (17+/-2 mg kg(-1)). Different fractions of EC-OC for tire-wear have been analyzed, and unlike exhaust emissions, EC1 was observed to be 99% of EC whereas more than 70% of the OC was the high temperature carbon (OC3 and OC4). The overall emission factors (mass tire(-1) km(-1)) for PAHs, EC and OC from tire-wear are 378 ng tire(-1) km(-1), 1.46 mg tire(-1) km(-1) and 2.37 mg tire(-1) km(-1) for small cars. Copyright 2010 Elsevier B.V. All rights reserved.

Interactive effects of age and exercise on adiposity measures of41,582 physically active women

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Paul T.; Satariano William A.

2004-06-01

The objective of this report is to assess in women whether exercise affects the estimated age-related increase in adiposity, and contrariwise, whether age affects the estimated exercise-related decrease in adiposity. Cross-sectional analyses of 64,911 female runners who provided data on their body mass index (97.6 percent), waist (91.1percent), and chest circumferences (77.9 percent). Age affected the relationships between vigorous exercise and adiposity. The decline in BMI per km/wk run was linear in 18-25 year olds (-0.023+-0.002 kg/m2 perkm run) and became increasingly nonlinear (convex or upwardly concave) with age. The waist, hip and chest circumferences declined significantly with running distancemore » across all age groups, but the declines were 52-58 percent greater in older than younger women (P<10-5). The relationships between body circumferences and running distance became increasingly convexity (upward concavity) in older women. Conversely, vigorous exercise diminished the apparent increase in adiposity with age. The rise in average BMI with age was greatest in women who ran less than 8 km/week (0.065+-0.005 kg/m2 per y), intermediate of women who ran 8-16km/wk (0.025+-0.004kg/m2 per y) or 16-32 km/wk (0.022+-0.003 kg/m2 pery), and least in those who averaged over 32 km/wk (0.017+-0.001 kg/m2 pery). Before age 45, waist circumference rose 0.055+-0.026 cm in for those who ran 0-8 km/wk, showed no significant change for those who ran 8-40km./wk, and declined -0.057+-0.012 and -0.069+-0.014 cm per year in those who ran 40 -56 and over 56 km/wk. The rise in hip and chest circumferences with age were significantly greater in women who ran under eight km/wk than longer distance runners for hip (0.231+-0.018 vs0.136+-0.004 cm/year) and chest circumferences (0.137+-0.013 vs0.053+-0.003 cm/year). These cross-sectional associations suggest that in women, age and vigorous exercise interact with each other in affecting adiposity. The extent that these cross-sectional associations are causally related to vigorous exercise or are the consequence of self-selection remains to be determined.« less

High Resolution Simulations of Future Climate in West Africa Using a Variable-Resolution Atmospheric Model

NASA Astrophysics Data System (ADS)

Adegoke, J. O.; Engelbrecht, F.; Vezhapparambu, S.

2013-12-01

In previous work demonstrated the application of a var¬iable-resolution global atmospheric model, the conformal-cubic atmospheric model (CCAM), across a wide range of spatial and time scales to investigate the ability of the model to provide realistic simulations of present-day climate and plausible projections of future climate change over sub-Saharan Africa. By applying the model in stretched-grid mode the versatility of the model dynamics, numerical formulation and physical parameterizations to function across a range of length scales over the region of interest, was also explored. We primarily used CCAM to illustrate the capability of the model to function as a flexible downscaling tool at the climate-change time scale. Here we report on additional long term climate projection studies performed by downscaling at much higher resolutions (8 Km) over an area that stretches from just south of Sahara desert to the southern coast of the Niger Delta and into the Gulf of Guinea. To perform these simulations, CCAM was provided with synoptic-scale forcing of atmospheric circulation from 2.5 deg resolution NCEP reanalysis at 6-hourly interval and SSTs from NCEP reanalysis data uses as lower boundary forcing. CCAM 60 Km resolution downscaled to 8 Km (Schmidt factor 24.75) then 8 Km resolution simulation downscaled to 1 Km (Schmidt factor 200) over an area approximately 50 Km x 50 Km in the southern Lake Chad Basin (LCB). Our intent in conducting these high resolution model runs was to obtain a deeper understanding of linkages between the projected future climate and the hydrological processes that control the surface water regime in this part of sub-Saharan Africa.

Similar Running Economy With Different Running Patterns Along the Aerial-Terrestrial Continuum.

PubMed

Lussiana, Thibault; Gindre, Cyrille; Hébert-Losier, Kim; Sagawa, Yoshimasa; Gimenez, Philippe; Mourot, Laurent

2017-04-01

No unique or ideal running pattern is the most economical for all runners. Classifying the global running patterns of individuals into 2 categories (aerial and terrestrial) using the Volodalen method could permit a better understanding of the relationship between running economy (RE) and biomechanics. The main purpose was to compare the RE of aerial and terrestrial runners. Two coaches classified 58 runners into aerial (n = 29) or terrestrial (n = 29) running patterns on the basis of visual observations. RE, muscle activity, kinematics, and spatiotemporal parameters of both groups were measured during a 5-min run at 12 km/h on a treadmill. Maximal oxygen uptake (V̇O 2 max) and peak treadmill speed (PTS) were assessed during an incremental running test. No differences were observed between aerial and terrestrial patterns for RE, V̇O 2 max, and PTS. However, at 12 km/h, aerial runners exhibited earlier gastrocnemius lateralis activation in preparation for contact, less dorsiflexion at ground contact, higher coactivation indexes, and greater leg stiffness during stance phase than terrestrial runners. Terrestrial runners had more pronounced semitendinosus activation at the start and end of the running cycle, shorter flight time, greater leg compression, and a more rear-foot strike. Different running patterns were associated with similar RE. Aerial runners appear to rely more on elastic energy utilization with a rapid eccentric-concentric coupling time, whereas terrestrial runners appear to propel the body more forward rather than upward to limit work against gravity. Excluding runners with a mixed running pattern from analyses did not affect study interpretation.

Impact of CYGNSS Data on Tropical Cyclone Analyses and Forecasts in a Regional OSSE Framework

NASA Astrophysics Data System (ADS)

Annane, B.; McNoldy, B. D.; Leidner, S. M.; Atlas, R. M.; Hoffman, R.; Majumdar, S.

2016-12-01

The Cyclone Global Navigation Satellite System, or CYGNSS, is a planned constellation of micro-satellites that will utilize reflected Global Positioning System (GPS) satellite signals to retrieve ocean surface wind speed along the satellites' ground tracks. The orbits are designed so that there is excellent coverage of the tropics and subtropics, resulting in more thorough spatial sampling and improved sampling intervals over tropical cyclones than is possible with current spaceborne scatterometer and passive microwave sensor platforms. Furthermore, CYGNSS will be able to retrieve winds under all precipitating conditions, and over a large range of wind speeds.A regional Observing System Simulation Experiment (OSSE) framework was developed at NOAA/AOML and University of Miami that features a high-resolution regional nature run (27-km regional domain with 9/3/1 km storm-following nests; Nolan et al., 2013) embedded within a lower-resolution global nature run . Simulated observations are generated by sampling from the nature run and are provided to a data assimilation scheme, which produces analyses for a high-resolution regional forecast model, the 2014 operational Hurricane-WRF model. For data assimilation, NOAA's GSI and EnKF systems are used. Analyses are performed on the parent domain at 9-km resolution. The forecast model uses a single storm-following 3-km resolution nest. Synthetic CYGNSS wind speed data have also been created, and the impacts of the assimilation of these data on the forecasts of tropical cyclone track and intensity will be discussed.In addition to the choice of assimilation scheme, we have also examined a number of other factors/parameters that effect the impact of simulated CYGNSS observations, including frequency of data assimilation cycling (e.g., hourly, 3-hourly and 6-hourly) and the assimilation of scalar versus vector synthetic CYGNSS winds.We have found sensitivity to all of the factors tested and will summarize the methods used for testing as well as results. Generally, we have found that more frequent cycling is better than less; and flow-dependent background error covariances (e.g., EnKF) are better than static or climatological assumptions about the background error covariance.

Improved detection and false alarm rejection for chemical vapors using passive hyperspectral imaging

NASA Astrophysics Data System (ADS)

Marinelli, William J.; Miyashiro, Rex; Gittins, Christopher M.; Konno, Daisei; Chang, Shing; Farr, Matt; Perkins, Brad

2013-05-01

Two AIRIS sensors were tested at Dugway Proving Grounds against chemical agent vapor simulants. The primary objectives of the test were to: 1) assess performance of algorithm improvements designed to reduce false alarm rates with a special emphasis on solar effects, and 3) evaluate performance in target detection at 5 km. The tests included 66 total releases comprising alternating 120 kg glacial acetic acid (GAA) and 60 kg triethyl phosphate (TEP) events. The AIRIS sensors had common algorithms, detection thresholds, and sensor parameters. The sensors used the target set defined for the Joint Service Lightweight Chemical Agent Detector (JSLSCAD) with TEP substituted for GA and GAA substituted for VX. They were exercised at two sites located at either 3 km or 5 km from the release point. Data from the tests will be presented showing that: 1) excellent detection capability was obtained at both ranges with significantly shorter alarm times at 5 km, 2) inter-sensor comparison revealed very comparable performance, 3) false alarm rates < 1 incident per 10 hours running time over 143 hours of sensor operations were achieved, 4) algorithm improvements eliminated both solar and cloud false alarms. The algorithms enabling the improved false alarm rejection will be discussed. The sensor technology has recently been extended to address the problem of detection of liquid and solid chemical agents and toxic industrial chemical on surfaces. The phenomenology and applicability of passive infrared hyperspectral imaging to this problem will be discussed and demonstrated.

Changes in Running Mechanics During a 6-Hour Running Race.

PubMed

Giovanelli, Nicola; Taboga, Paolo; Lazzer, Stefano

2017-05-01

To investigate changes in running mechanics during a 6-h running race. Twelve ultraendurance runners (age 41.9 ± 5.8 y, body mass 68.3 ± 12.6 kg, height 1.72 ± 0.09 m) were asked to run as many 874-m flat loops as possible in 6 h. Running speed, contact time (t c ), and aerial time (t a ) were measured in the first lap and every 30 ± 2 min during the race. Peak vertical ground-reaction force (F max ), stride length (SL), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), vertical stiffness (k vert ), and leg stiffness (k leg ) were then estimated. Mean distance covered by the athletes during the race was 62.9 ± 7.9 km. Compared with the 1st lap, running speed decreased significantly from 4 h 30 min onward (mean -5.6% ± 0.3%, P < .05), while t c increased after 4 h 30 min of running, reaching the maximum difference after 5 h 30 min (+6.1%, P = .015). Conversely, k vert decreased after 4 h, reaching the lowest value after 5 h 30 min (-6.5%, P = .008); t a and F max decreased after 4 h 30 min through to the end of the race (mean -29.2% and -5.1%, respectively, P < .05). Finally, SL decreased significantly (-5.1%, P = .010) during the last hour of the race. Most changes occurred after 4 h continuous self-paced running, suggesting a possible time threshold that could affect performance regardless of absolute running speed.

Are Females More Resistant to Extreme Neuromuscular Fatigue?

PubMed

Temesi, John; Arnal, Pierrick J; Rupp, Thomas; Féasson, Léonard; Cartier, Régine; Gergelé, Laurent; Verges, Samuel; Martin, Vincent; Millet, Guillaume Y

2015-07-01

Despite interest in the possibility of females outperforming males in ultraendurance sporting events, little is known about the sex differences in fatigue during prolonged locomotor exercise. This study investigated possible sex differences in central and peripheral fatigue in the knee extensors and plantar flexors resulting from a 110-km ultra-trail-running race. Neuromuscular function of the knee extensors and plantar flexors was evaluated via transcranial magnetic stimulation (TMS) and electrical nerve stimulation before and after an ultra-trail-running race in 20 experienced ultraendurance trail runners (10 females and 10 males matched by percent of the winning time by sex) during maximal and submaximal voluntary contractions and in relaxed muscle. Maximal voluntary knee extensor torque decreased more in males than in females (-38% vs -29%, P = 0.006) although the reduction in plantar flexor torque was similar between sexes (-26% vs -31%). Evoked mechanical plantar flexor responses decreased more in males than in females (-23% vs -8% for potentiated twitch amplitude, P = 0.010), indicating greater plantar flexor peripheral fatigue in males. Maximal voluntary activation assessed by TMS and electrical nerve stimulation decreased similarly in both sexes for both muscle groups. Indices of knee extensor peripheral fatigue and corticospinal excitability and inhibition changes were also similar for both sexes. Females exhibited less peripheral fatigue in the plantar flexors than males did after a 110-km ultra-trail-running race and males demonstrated a greater decrease in maximal force loss in the knee extensors. There were no differences in the magnitude of central fatigue for either muscle group or TMS-induced outcomes. The lower level of fatigue in the knee extensors and peripheral fatigue in the plantar flexors could partly explain the reports of better performance in females in extreme duration running races as race distance increases.

Extraordinary flood response of a small urban watershed to short-duration convective rainfall

USGS Publications Warehouse

Smith, J.A.; Miller, A.J.; Baeck, M.L.; Nelson, P.A.; Fisher, G.T.; Meierdiercks, K.L.

2005-01-01

The 9.1 km2 Moores Run watershed in Baltimore, Maryland, experiences floods with unit discharge peaks exceeding 1 m3 s-1 km-2 12 times yr-1, on average. Few, if any, drainage basins in the continental United States have a higher frequency. A thunderstorm system on 13 June 2003 produced the record flood peak (13.2 m3 s-1 km-2) during the 6-yr stream gauging record of Moores Run. In this paper, the hydrometeorology, hydrology, and hydraulics of extreme floods in Moores Run are examined through analyses of the 13 June 2003 storm and flood, as well as other major storm and flood events during the 2000-03 time period. The 13 June 2003 flood, like most floods in Moores Run, was produced by an organized system of thunderstorms. Analyses of the 13 June 2003 storm, which are based on volume scan reflectivity observations from the Sterling, Virginia, WSR-88D radar, are used to characterize the spatial and temporal variability of flash flood producing rainfall. Hydrology of flood response in Moores Run is characterized by highly efficient concentration of runoff through the storm drain network and relatively low runoff ratios. A detailed survey of high-water marks for the 13 June 2003 flood is used, in combination with analyses based on a 2D, depth-averaged open channel flow model (TELEMAC 2D) to examine hydraulics of the 13 June 2003 flood. Hydraulic analyses are used to examine peak discharge estimates for the 13 June flood peak, propagation of flood waves in the Moores Run channel, and 2D flow features associated with channel and floodplain geometry. ?? 2005 American Meteorological Society.

Running from Paris to Beijing: biomechanical and physiological consequences.

PubMed

Millet, Guillaume Y; Morin, Jean-Benoît; Degache, Francis; Edouard, Pascal; Feasson, Léonard; Verney, Julien; Oullion, Roger

2009-12-01

The purpose of this study was to examine the physiological and biomechanical changes occurring in a subject after running 8,500 km in 161 days (i.e. 52.8 km daily). Three weeks before, 3 weeks after (POST) and 5 months after (POST+5) running from Paris to Beijing, energy cost of running (Cr), knee flexor and extensor isokinetic strength and biomechanical parameters (using a treadmill dynamometer) at different velocities were assessed in an experienced ultra-runner. At POST, there was a tendency toward a 'smoother' running pattern, as shown by (a) a higher stride frequency and duty factor, and a reduced aerial time without a change in contact time, (b) a lower maximal vertical force and loading rate at impact and (c) a decrease in both potential and kinetic energy changes at each step. This was associated with a detrimental effect on Cr (+6.2%) and a loss of strength at all angular velocities for both knee flexors and extensors. At POST+5, the subject returned to his original running patterns at low but not at high speeds and maximal strength remained reduced at low angular velocities (i.e. at high levels of force). It is suggested that the running pattern changes observed in the present study were a strategy adopted by the subject to reduce the deleterious effects of long distance running. However, the running pattern changes could partly be linked to the decrease in maximal strength.

Evaluation and projected changes of precipitation statistics in convection-permitting WRF climate simulations over Central Europe

NASA Astrophysics Data System (ADS)

Knist, Sebastian; Goergen, Klaus; Simmer, Clemens

2018-02-01

We perform simulations with the WRF regional climate model at 12 and 3 km grid resolution for the current and future climates over Central Europe and evaluate their added value with a focus on the daily cycle and frequency distribution of rainfall and the relation between extreme precipitation and air temperature. First, a 9 year period of ERA-Interim driven simulations is evaluated against observations; then global climate model runs (MPI-ESM-LR RCP4.5 scenario) are downscaled and analyzed for three 12-year periods: a control, a mid-of-century and an end-of-century projection. The higher resolution simulations reproduce both the diurnal cycle and the hourly intensity distribution of precipitation more realistically compared to the 12 km simulation. Moreover, the observed increase of the temperature-extreme precipitation scaling from the Clausius-Clapeyron (C-C) scaling rate of 7% K-1 to a super-adiabatic scaling rate for temperatures above 11 °C is reproduced only by the 3 km simulation. The drop of the scaling rates at high temperatures under moisture limited conditions differs between sub-regions. For both future scenario time spans both simulations suggest a slight decrease in mean summer precipitation and an increase in hourly heavy and extreme precipitation. This increase is stronger in the 3 km runs. Temperature-extreme precipitation scaling curves in the future climate are projected to shift along the 7% K-1 trajectory to higher peak extreme precipitation values at higher temperatures. The curves keep their typical shape of C-C scaling followed by super-adiabatic scaling and a drop-off at higher temperatures due to moisture limitation.

Verification of the NWP models operated at ICM, Poland

NASA Astrophysics Data System (ADS)

Melonek, Malgorzata

2010-05-01

Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw (ICM) started its activity in the field of NWP in May 1997. Since this time the numerical weather forecasts covering Central Europe have been routinely published on our publicly available website. First NWP model used in ICM was hydrostatic Unified Model developed by the UK Meteorological Office. It was a mesoscale version with horizontal resolution of 17 km and 31 levels in vertical. At present two NWP non-hydrostatic models are running in quasi-operational regime. The main new UM model with 4 km horizontal resolution, 38 levels in vertical and forecats range of 48 hours is running four times a day. Second, the COAMPS model (Coupled Ocean/Atmosphere Mesoscale Prediction System) developed by the US Naval Research Laboratory, configured with the three nested grids (with coresponding resolutions of 39km, 13km and 4.3km, 30 vertical levels) are running twice a day (for 00 and 12 UTC). The second grid covers Central Europe and has forecast range of 84 hours. Results of the both NWP models, ie. COAMPS computed on 13km mesh resolution and UM, are verified against observations from the Polish synoptic stations. Verification uses surface observations and nearest grid point forcasts. Following meteorological elements are verified: air temperature at 2m, mean sea level pressure, wind speed and wind direction at 10 m and 12 hours accumulated precipitation. There are presented different statistical indices. For continous variables Mean Error(ME), Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE) in 6 hours intervals are computed. In case of precipitation the contingency tables for different thresholds are computed and some of the verification scores such as FBI, ETS, POD, FAR are graphically presented. The verification sample covers nearly one year.

The role of global cloud climatologies in validating numerical models

NASA Technical Reports Server (NTRS)

HARSHVARDHAN

1993-01-01

The purpose of this work is to estimate sampling errors of area-time averaged rain rate due to temporal samplings by satellites. In particular, the sampling errors of the proposed low inclination orbit satellite of the Tropical Rainfall Measuring Mission (TRMM) (35 deg inclination and 350 km altitude), one of the sun synchronous polar orbiting satellites of NOAA series (98.89 deg inclination and 833 km altitude), and two simultaneous sun synchronous polar orbiting satellites--assumed to carry a perfect passive microwave sensor for direct rainfall measurements--will be estimated. This estimate is done by performing a study of the satellite orbits and the autocovariance function of the area-averaged rain rate time series. A model based on an exponential fit of the autocovariance function is used for actual calculations. Varying visiting intervals and total coverage of averaging area on each visit by the satellites are taken into account in the model. The data are generated by a General Circulation Model (GCM). The model has a diurnal cycle and parameterized convective processes. A special run of the GCM was made at NASA/GSFC in which the rainfall and precipitable water fields were retained globally for every hour of the run for the whole year.

Musculoskeletal injuries in the ultramarathon: the 1990 Westfield Sydney to Melbourne run.

PubMed Central

Fallon, K E

1996-01-01

OBJECTIVE: To document the injuries sustained by participants in a 1005 km ultramarathon. METHODS: Clinical notes were reviewed on entrants in the 1005 km Sydney to Melbourne ultramarathon. An injury was recorded following self referral by a participant or if the history obtained from the runner or his support crew indicated the likelihood of a significant injury which could have an impact upon performance. RESULTS: 64 injuries were found in 32 runners. The knee (31.3%) and ankle (28.1%) regions were most commonly injured. The most common single diagnosis was retropatellar pain syndrome, and Achilles tendinitis and medial tibial stress syndrome were the next most common injuries. Peritendinitis/tendinitis of the tendons passing under the extensor retinaculum at the ankle, an injury infrequently reported in other sports, was common (19% of all injuries). CONCLUSIONS: The injuries were typically associated with running but 12 (19% of the total) involved the tendons of the muscles of the anterior compartment of the lower leg, and in almost every case the major site of inflammation was at the extensor retinaculum at the anterior aspect of the ankle. This injury appears to be relatively specific to the ultramarathon-"ultramarathoner's ankle". Images p321-a PMID:9015594

The Energy Cost of Running with the Ball in Soccer.

PubMed

Piras, Alessandro; Raffi, Milena; Atmatzidis, Charalampos; Merni, Franco; Di Michele, Rocco

2017-11-01

Running with the ball is a soccer-specific activity frequently used by players during match play and training drills. Nevertheless, the energy cost (EC) of on-grass running with the ball has not yet been determined. The purpose of this study was therefore to assess the EC of constant-speed running with the ball, and to compare it with the EC of normal running. Eight amateur soccer players performed two 6- min runs at 10 km/h on artificial turf, respectively with and without the ball. EC was measured with indirect calorimetry and, furthermore, estimated with a method based on players' accelerations measured with a GPS receiver. The EC measured with indirect calorimetry was higher in running with the ball (4.60±0.42 J/kg/m) than in normal running (4.19±0.33 J/kg/m), with a very likely moderate difference between conditions. Instead, a likely small difference was observed between conditions for EC estimated from GPS data (4.87±0.07 vs. 4.83±0.08 J/kg/m). This study sheds light on the energy expenditure of playing soccer, providing relevant data about the EC of a typical soccer-specific activity. These findings may be a reference for coaches to precisely determine the training load in drills with the ball, such as soccer-specific circuits or small-sided games. © Georg Thieme Verlag KG Stuttgart · New York.

TESTING CMAQ CHEMISTRY SENSITIVITIES IN BASE CHASE AND EMISSION CONTROL RUNS AT SEARCH AND SOS 99 SURFACE SITES IN THE SOUTHEASTERN UNITED STATES

EPA Science Inventory

CMAQ was run to simulate urban conditions in the southeastern U.S. in July 1999 at 32, 8, and 2 km grid spacings. Runs were made with two older mechanisms, Carbon Bond IV (CB4) and the Regional Acid Deposition Model, version 2 (RADM2), and with the more recent California Statewid...

Observations of running penumbral waves.

NASA Technical Reports Server (NTRS)

Zirin, H.; Stein, A.

1972-01-01

Quiet sunspots with well-developed penumbrae show running intensity waves with period running around 300 sec. The waves appear connected with umbral flashes of exactly half the period. Waves are concentric, regular, with velocity constant around 10 km/sec. They are probably sound waves and show intensity fluctuation in H alpha centerline or wing of 10 to 20%. The energy is tiny compared to the heat deficit of the umbra.

Mesoscale atmospheric modelling technology as a tool for the long-term meteorological dataset development

NASA Astrophysics Data System (ADS)

Platonov, Vladimir; Kislov, Alexander; Rivin, Gdaly; Varentsov, Mikhail; Rozinkina, Inna; Nikitin, Mikhail; Chumakov, Mikhail

2017-04-01

The detailed hydrodynamic modelling of meteorological parameters during the last 30 years (1985 - 2014) was performed for the Okhotsk Sea and the Sakhalin island regions. The regional non-hydrostatic atmospheric model COSMO-CLM used for this long-term simulation with 13.2, 6.6 and 2.2 km horizontal resolutions. The main objective of creation this dataset was the outlook of the investigation of statistical characteristics and the physical mechanisms of extreme weather events (primarily, wind speed extremes) on the small spatio-temporal scales. COSMO-CLM is the climate version of the well-known mesoscale COSMO model, including some modifications and extensions adapting to the long-term numerical experiments. The downscaling technique was realized and developed for the long-term simulations with three consequent nesting domains. ERA-Interim reanalysis ( 0.75 degrees resolution) used as global forcing data for the starting domain ( 13.2 km horizontal resolution), then these simulation data used as initial and boundary conditions for the next model runs over the domain with 6.6 km resolution, and similarly, for the next step to 2.2 km domain. Besides, the COSMO-CLM model configuration for 13.2 km run included the spectral nudging technique, i.e. an additional assimilation of reanalysis data not only at boundaries, but also inside the whole domain. Practically, this computational scheme realized on the SGI Altix 4700 supercomputer system in the Main Computer Center of Roshydromet and used 2,400 hours of CPU time total. According to modelling results, the verification of the obtained dataset was performed on the observation data. Estimations showed the mean error -0.5 0C, up to 2 - 3 0C RMSE in temperature, and overestimation in wind speed (RMSE is up to 2 m/s). Overall, analysis showed that the used downscaling technique with applying the COSMO-CLM model reproduced the meteorological conditions, spatial distribution, seasonal and synoptic variability of temperature and wind speed for the study area adequately. The dependences between reproduction quality of mesoscale atmospheric circulation features and the horizontal resolution of the model were revealed. In particular, it is shown that the use of 6 km resolution does not give any significant improvement comparing to 13 km resolution, whereas 2.2 km resolution provides an appreciable quality enhancement. Detailed synoptic analysis of extreme wind speed situations identified the main types of favorable to their genesis, associated with developing of cyclones over the Japan Islands or the Primorsky Kray of Russia, and penetration of intensified cyclones from Pacific Ocean through the Kamchatka peninsula, Kuril or Japan Islands. The obtained dataset will continue to be used for a full and comprehensive analysis of the reproduction quality of hydrometeorological fields, their statistical estimates, climatological trends and many other objectives.

Redistribution of Mechanical Work at the Knee and Ankle Joints During Fast Running in Minimalist Shoes

PubMed Central

Fuller, Joel T.; Buckley, Jonathan D.; Tsiros, Margarita D.; Brown, Nicholas A. T.; Thewlis, Dominic

2016-01-01

Context: Minimalist shoes have been suggested as a way to alter running biomechanics to improve running performance and reduce injuries. However, to date, researchers have only considered the effect of minimalist shoes at slow running speeds. Objective: To determine if runners change foot-strike pattern and alter the distribution of mechanical work at the knee and ankle joints when running at a fast speed in minimalist shoes compared with conventional running shoes. Design: Crossover study. Setting: Research laboratory. Patients or Other Participants: Twenty-six trained runners (age = 30.0 ± 7.9 years [age range, 18−40 years], height = 1.79 ± 0.06 m, mass = 75.3 ± 8.2 kg, weekly training distance = 27 ± 15 km) who ran with a habitual rearfoot foot-strike pattern and had no experience running in minimalist shoes. Intervention(s): Participants completed overground running trials at 18 km/h in minimalist and conventional shoes. Main Outcome Measure(s): Sagittal-plane kinematics and joint work at the knee and ankle joints were computed using 3-dimensional kinematic and ground reaction force data. Foot-strike pattern was classified as rearfoot, midfoot, or forefoot strike based on strike index and ankle angle at initial contact. Results: We observed no difference in foot-strike classification between shoes (χ21 = 2.29, P = .13). Ankle angle at initial contact was less (2.46° versus 7.43°; t25 = 3.34, P = .003) and strike index was greater (35.97% versus 29.04%; t25 = 2.38, P = .03) when running in minimalist shoes compared with conventional shoes. We observed greater negative (52.87 J versus 42.46 J; t24 = 2.29, P = .03) and positive work (68.91 J versus 59.08 J; t24 = 2.65, P = .01) at the ankle but less negative (59.01 J versus 67.02 J; t24 = 2.25, P = .03) and positive work (40.37 J versus 47.09 J; t24 = 2.11, P = .046) at the knee with minimalist shoes compared with conventional shoes. Conclusions: Running in minimalist shoes at a fast speed caused a redistribution of work from the knee to the ankle joint. This finding suggests that runners changing from conventional to minimalist shoes for short-distance races could be at an increased risk of ankle and calf injuries but a reduced risk of knee injuries. PMID:27834504

Factors affecting metabolic cost of transport during a multi-stage running race.

PubMed

Lazzer, Stefano; Taboga, Paolo; Salvadego, Desy; Rejc, Enrico; Simunic, Bostjan; Narici, Marco V; Buglione, Antonio; Giovanelli, Nicola; Antonutto, Guglielmo; Grassi, Bruno; Pisot, Rado; di Prampero, Pietro E

2014-03-01

The aim of this study was to investigate: (1) the role of , the fraction of (F) and the metabolic cost of transport (CoT) in determining performance during an ultra-endurance competition and (2) the effects of the race on several biomechanical and morphological parameters of the lower limbs that are likely to affect CoT. Eleven runners (aged 29-54 years) participated in an ultra-endurance competition consisting of three running stages of 25, 55 and 13 km on three consecutive days. Anthropometric characteristics, body composition, morphological properties of the gastrocnemius medialis, maximal explosive power of the lower limb and were determined before the competition. In addition, biomechanics of running and CoT were determined, before and immediately after each running stage. Performance was directly proportional to (r=0.77) and F (r=0.36), and inversely proportional to CoT (r=-0.30). Low CoT values were significantly related to high maximal power of the lower limbs (r=-0.74) and vertical stiffness (r=-0.65) and low footprint index (FPI, r=0.70), step frequency (r=0.62) and external work (r=0.60). About 50% of the increase in CoT during the stages of the competition was accounted for by changes in FPI, which represents a global evaluation of medio-lateral displacement of the foot during the whole stance phase, which in turn is associated with the myotendinous characteristics of the lower limb. Thus, lower CoT values were related to greater muscular power and lower FPI, suggesting that a better ankle stability is likely to achieve better performance in an ultra-endurance running competition.

Large-eddy simulation of dust-uplift by a haboob density current

NASA Astrophysics Data System (ADS)

Huang, Qian; Marsham, John H.; Tian, Wenshou; Parker, Douglas J.; Garcia-Carreras, Luis

2018-04-01

Cold pool outflows have been shown from both observations and convection-permitting models to be a dominant source of dust emissions ("haboobs") in the summertime Sahel and Sahara, and to cause dust uplift over deserts across the world. In this paper Met Office Large Eddy Model (LEM) simulations, which resolve the turbulence within the cold-pools much better than previous studies of haboobs with convection-permitting models, are used to investigate the winds that uplift dust in cold pools, and the resultant dust transport. In order to simulate the cold pool outflow, an idealized cooling is added in the model during the first 2 h of 5.7 h run time. Given the short duration of the runs, dust is treated as a passive tracer. Dust uplift largely occurs in the "head" of the density current, consistent with the few existing observations. In the modeled density current dust is largely restricted to the lowest, coldest and well mixed layers of the cold pool outflow (below around 400 m), except above the "head" of the cold pool where some dust reaches 2.5 km. This rapid transport to above 2 km will contribute to long atmospheric lifetimes of large dust particles from haboobs. Decreasing the model horizontal grid-spacing from 1.0 km to 100 m resolves more turbulence, locally increasing winds, increasing mixing and reducing the propagation speed of the density current. Total accumulated dust uplift is approximately twice as large in 1.0 km runs compared with 100 m runs, suggesting that for studying haboobs in convection-permitting runs the representation of turbulence and mixing is significant. Simulations with surface sensible heat fluxes representative of those from a desert region during daytime show that increasing surface fluxes slows the density current due to increased mixing, but increase dust uplift rates, due to increased downward transport of momentum to the surface.

What model resolution is required in climatological downscaling over complex terrain?

NASA Astrophysics Data System (ADS)

El-Samra, Renalda; Bou-Zeid, Elie; El-Fadel, Mutasem

2018-05-01

This study presents results from the Weather Research and Forecasting (WRF) model applied for climatological downscaling simulations over highly complex terrain along the Eastern Mediterranean. We sequentially downscale general circulation model results, for a mild and wet year (2003) and a hot and dry year (2010), to three local horizontal resolutions of 9, 3 and 1 km. Simulated near-surface hydrometeorological variables are compared at different time scales against data from an observational network over the study area comprising rain gauges, anemometers, and thermometers. The overall performance of WRF at 1 and 3 km horizontal resolution was satisfactory, with significant improvement over the 9 km downscaling simulation. The total yearly precipitation from WRF's 1 km and 3 km domains exhibited < 10% bias with respect to observational data. The errors in minimum and maximum temperatures were reduced by the downscaling, along with a high-quality delineation of temperature variability and extremes for both the 1 and 3 km resolution runs. Wind speeds, on the other hand, are generally overestimated for all model resolutions, in comparison with observational data, particularly on the coast (up to 50%) compared to inland stations (up to 40%). The findings therefore indicate that a 3 km resolution is sufficient for the downscaling, especially that it would allow more years and scenarios to be investigated compared to the higher 1 km resolution at the same computational effort. In addition, the results provide a quantitative measure of the potential errors for various hydrometeorological variables.

A comparison of methods to quantify the in-season training load of professional soccer players.

PubMed

Scott, Brendan R; Lockie, Robert G; Knight, Timothy J; Clark, Andrew C; Janse de Jonge, Xanne A K

2013-03-01

To compare various measures of training load (TL) derived from physiological (heart rate [HR]), perceptual (rating of perceived exertion [RPE]), and physical (global positioning system [GPS] and accelerometer) data during in-season field-based training for professional soccer. Fifteen professional male soccer players (age 24.9 ± 5.4 y, body mass 77.6 ± 7.5 kg, height 181.1 ± 6.9 cm) were assessed in-season across 97 individual training sessions. Measures of external TL (total distance [TD], the volume of low-speed activity [LSA; <14.4 km/h], high-speed running [HSR; >14.4 km/h], very high-speed running [VHSR; >19.8 km/h], and player load), HR and session-RPE (sRPE) scores were recorded. Internal TL scores (HR-based and sRPE-based) were calculated, and their relationships with measures of external TL were quantified using Pearson product-moment correlations. Physical measures of TD, LSA volume, and player load provided large, significant (r = .71-.84; P < .01) correlations with the HR-based and sRPE-based methods. Volume of HSR and VHSR provided moderate to large, significant (r = .40-.67; P < .01) correlations with measures of internal TL. While the volume of HSR and VHSR provided significant relationships with internal TL, physical-performance measures of TD, LSA volume, and player load appear to be more acceptable indicators of external TL, due to the greater magnitude of their correlations with measures of internal TL.

The 2004 Opposition of Ceres Observed with Adaptive Optics on the VLT

NASA Technical Reports Server (NTRS)

Erard, S.; Frorni, O.; Ollivier, M.; Dotto, E.; Roush, T.; Poulet, F.; Mueller, T.

2005-01-01

The close opposition of Ceres in January 2004 has been observed with the NACO adaptive optics system on the VLT. Both imaging and spectroscopy were performed in the 1.1-4.1 m range. Extensive longitudinal coverage was acquired during a three days run, with spatial resolution up to 50 km in imaging mode. The scientific objectives are 1) to provide the first IR map of Ceres; 2) to map possible compositional variations at the surface. Only imaging results are presented here.

Vizualization Challenges of a Subduction Simulation Using One Billion Markers

NASA Astrophysics Data System (ADS)

Rudolph, M. L.; Gerya, T. V.; Yuen, D. A.

2004-12-01

Recent advances in supercomputing technology have permitted us to study the multiscale, multicomponent fluid dynamics of subduction zones at unprecedented resolutions down to about the length of a football field. We have performed numerical simulations using one billion tracers over a grid of about 80 thousand points in two dimensions. These runs have been performed using a thermal-chemical simulation that accounts for hydration and partial melting in the thermal, mechanical, petrological, and rheological domains. From these runs, we have observed several geophysically interesting phenomena including the development of plumes with unmixed mantle composition as well as plumes with mixed mantle/crust components. Unmixed plumes form at depths greater than 100km (5-10 km above the upper interface of subducting slab) and consist of partially molten wet peridotite. Mixed plumes form at lesser depth directly from the subducting slab and contain partially molten hydrated oceanic crust and sediments. These high resolution simulations have also spurred the development of new visualization methods. We have created a new web-based interface to data from our subduction simulation and other high-resolution 2D data that uses an hierarchical data format to achieve response times of less than one second when accessing data files on the order of 3GB. This interface, WEB-IS4, uses a Javascript and HTML frontend coupled with a C and PHP backend and allows the user to perform region of interest zooming, real-time colormap selection, and can return relevant statistics relating to the data in the region of interest.

Metabolic, Cardiopulmonary, and Gait Profiles of Recently Injured and Noninjured Runners

PubMed Central

Peng, Lucinda; Seay, Amanda N.; Montero, Cindy; Barnes, Leslie L.; Vincent, Kevin R.; Conrad, Bryan P.; Chen, Cong; Vincent, Heather K.

2017-01-01

Objective To examine whether runners recovering from a lower body musculoskeletal injury have different metabolic, cardiopulmonary, and gait responses compared with healthy runners. Design Cross-sectional study. Setting Research laboratory at an academic institution. Methods Healthy runners (n = 50) were compared with runners who were recently injured but had returned to running (n = 50). Both groups were participating in similar cross-training modalities such as swimming, weight training, biking, and yoga. Running gait was analyzed on a treadmill using 3-dimensional motion capture, and metabolic and cardiopulmonary measures were captured simultaneously with a portable metabolic analyzer. Main Outcome Measures Rate of oxygen consumption, heart rate, ventilation, carbohydrate and fat oxidation values, gait temporospatial parameters and range of motion measures (ROM) in the sagittal plane, energy expenditure, and vertical displacement of the body’s center of gravity (COG). Results The self-selected running speed was different between the injured and healthy runners (9.7 ± 1.1 km/h and 10.6 ± 1.1 km/h, respectively; P = .038). No significant group differences were noted in any metabolic or cardiopulmonary variable while running at the self-selected or standard speed (13.6 km/h). The vertical displacement of the COG was less in the injured group (8.4 ± 1.4 cm and 8.9 ± 1.4, respectively; P = .044). ROM about the right ankle in the sagittal plane at the self-selected running speed during the gait cycle was less in the injured runners compared with the healthy runners (P < .05). Conclusions Runners with a recent lower body injury who have returned to running have similar cardiopulmonary and metabolic responses to running as healthy runners at the self-selected and standard speeds; this finding may be due in part to participation in cross-training modes that preserve cardiopulmonary and metabolic adaptations. Injured runners may conserve motion by minimizing COG displacement and ankle joint ROM during a gait cycle. PMID:24998402

The Challenge of Evaluating the Intensity of Short Actions in Soccer: A New Methodological Approach Using Percentage Acceleration.

PubMed

Sonderegger, Karin; Tschopp, Markus; Taube, Wolfgang

2016-01-01

There are several approaches to quantifying physical load in team sports using positional data. Distances in different speed zones are most commonly used. Recent studies have used acceleration data in addition in order to take short intense actions into account. However, the fact that acceleration decreases with increasing initial running speed is ignored and therefore introduces a bias. The aim of our study was to develop a new methodological approach that removes this bias. For this purpose, percentage acceleration was calculated as the ratio of the maximal acceleration of the action (amax,action) and the maximal voluntary acceleration (amax) that can be achieved for a particular initial running speed (percentage acceleration [%] = amax,action / amax * 100). To define amax, seventy-two highly trained junior male soccer players (17.1 ± 0.6 years) completed maximal sprints from standing and three different constant initial running speeds (vinit; trotting: ~6.0 km·h-1; jogging: ~10.8 km·h-1; running: ~15.0 km·h-1). The amax was 6.01 ± 0.55 from a standing start, 4.33 ± 0.40 from trotting, 3.20 ± 0.49 from jogging and 2.29 ± 0.34 m·s-2 from running. The amax correlated significantly with vinit (r = -0.98) and the linear regression equation of highly-trained junior soccer players was: amax = -0.23 * vinit + 5.99. Using linear regression analysis, we propose to classify high-intensity actions as accelerations >75% of the amax, corresponding to acceleration values for our population of >4.51 initiated from standing, >3.25 from trotting, >2.40 from jogging, and >1.72 m·s-2 from running. The use of percentage acceleration avoids the bias of underestimating actions with high and overestimating actions with low initial running speed. Furthermore, percentage acceleration allows determining individual intensity thresholds that are specific for one population or one single player.

Evaluations of high-resolution dynamically downscaled ensembles over the contiguous United States Climate Dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zobel, Zachary; Wang, Jiali; Wuebbles, Donald J.

This study uses Weather Research and Forecast (WRF) model to evaluate the performance of six dynamical downscaled decadal historical simulations with 12-km resolution for a large domain (7200 x 6180 km) that covers most of North America. The initial and boundary conditions are from three global climate models (GCMs) and one reanalysis data. The GCMs employed in this study are the Geophysical Fluid Dynamics Laboratory Earth System Model with Generalized Ocean Layer Dynamics component, Community Climate System Model, version 4, and the Hadley Centre Global Environment Model, version 2-Earth System. The reanalysis data is from the National Centers for Environmentalmore » Prediction-US. Department of Energy Reanalysis II. We analyze the effects of bias correcting, the lateral boundary conditions and the effects of spectral nudging. We evaluate the model performance for seven surface variables and four upper atmospheric variables based on their climatology and extremes for seven subregions across the United States. The results indicate that the simulation’s performance depends on both location and the features/variable being tested. We find that the use of bias correction and/or nudging is beneficial in many situations, but employing these when running the RCM is not always an improvement when compared to the reference data. The use of an ensemble mean and median leads to a better performance in measuring the climatology, while it is significantly biased for the extremes, showing much larger differences than individual GCM driven model simulations from the reference data. This study provides a comprehensive evaluation of these historical model runs in order to make informed decisions when making future projections.« less

Weak Relationships between Stint Duration, Physical and Skilled Match Performance in Australian Football

PubMed Central

Corbett, David M.; Sweeting, Alice J.; Robertson, Sam

2017-01-01

Australian Rules football comprises physical and skilled performance for more than 90 min of play. The cognitive and physiological fatigue experienced by participants during a match may reduce performance. Consequently, the length of time an athlete is on the field before being interchanged (known as a stint), is a key tactic which could maximize the skill and physical output of the Australian Rules athlete. This study developed two methods to quantify the relationship between athlete time on field, skilled and physical output. Professional male athletes (n = 39) from a single elite Australian Rules football club participated, with physical output quantified via player tracking systems across 22 competitive matches. Skilled output was calculated as the sum of involvements performed by each athlete, collected from a commercial statistics company. A random intercept and slope model was built to identify how a team and individuals respond to physical outputs and stint lengths. Stint duration (mins), high intensity running (speeds >14.4 km · hr−1) per minute, meterage per minute and very high intensity running (speeds >25 km·hr−1) per minute had some relationship with skilled involvements. However, none of these relationships were strong, and the direction of influence for each player was varied. Three conditional inference trees were computed to identify the extent to which combinations of physical parameters altered the anticipated skilled output of players. Meterage per minute, player, round number and duration were all related to player involvement. All methods had an average error of 10 to 11 involvements, per player per match. Therefore, other factors aside from physical parameters extracted from wearable technologies may be needed to explain skilled output within Australian Rules football matches. PMID:29109688

Comparison of ventilation threshold and heart rate deflection point in fast and standard treadmill test protocols.

PubMed

Vucetić, Vlatko; Sentija, Davor; Sporis, Goran; Trajković, Nebojsa; Milanović, Zoran

2014-06-01

The purpose of this study was to compare two methods for determination of anaerobic threshold from two different treadmill protocols. Forty-eight Croatian runners of national rank (ten sprinters, fifteen 400-m runners, ten middle distance runners and thirteen long distance runners), mean age 21.7 +/- 5.1 years, participated in the study. They performed two graded maximal exercise tests on a treadmill, a standard ramp treadmill test (T(SR), speed increments of 1 km x h(-1) every 60 seconds) and a fast ramp treadmill test (T(FR), speed increments of 1 km x h(-1) every 30 seconds) to determine and compare the parameters at peak values and at heart rate at the deflection point (HR(DP)) and ventilation threshold (VT). There were no significant differences between protocols (p > 0.05) for peak values of oxygen uptake (VO(2max), 4.48 +/- 0.43 and 4.44 +/- 0.45 L x min(-1)), weight related VO(2max) (62.5 +/- 6.2 and 62.0 +/- 6.0 mL x kg(-1) x min(-1)), pulmonary ventilation (VE(max), 163.1 +/- 18.7 and 161.3 +/- 19.9 L x min(-1)) and heart rate (HR(max), 192.3 +/- 8.5 and 194.4 +/- 8.7 bpm) (T(FR) and T(SR), respectively). Moreover, no significant differences between T(FR) and T(SR) where found for VT and HR(DP) when expressed as VO2 and HR. However, there was a significant effect of ramp slope on running speed at VO(2max) and at the anaerobic threshold (AnT), independent of the method used (VT: 16.0 +/- 2.2 vs 14.9 +/- 2.2 km x h(-1);HR(DP): 16.5 +/- 1.9 vs 14.9 +/- 2.0 km x h(-1) for T(FR) and T(SR) respectively). Linear regression analysis revealed high between-test and between-method correlations for VO2, HR and running speed parameters (r = 0.78-0.89, p < 0.01). The present study has indicated that the VT and HR(DP) for running (VO2, ventilation, and heart rate at VT/HR(DP)) are independent of test protocol, while there is a significant effect of ramp slope on VT and HR(DP) when expressed as running speed. Moreover, this study demonstrates that the point of deflection from linearity of heart rate may be an accurate predictor of the anaerobic threshold in trained runners, independently of the protocol used.

Six Weeks Habituation of Simulated Barefoot Running Induces Neuromuscular Adaptations and Changes in Foot Strike Patterns in Female Runners

PubMed Central

Khowailed, Iman Akef; Petrofsky, Jerrold; Lohman, Everett; Daher, Noha

2015-01-01

Background The aim of this study was to examine the effects of a 6-week training program of simulated barefoot running (SBR) on running kinetics in habitually shod (wearing shoes) female recreational runners. Material/Methods Twelve female runners age 25.7±3.4 years gradually increased running distance in Vibram FiveFingers minimal shoes over a 6-week period. The kinetic analysis of treadmill running at 10 Km/h was performed pre- and post-intervention in shod running, non-habituated SBR, and habituated SBR conditions. Spatiotemporal parameters, ground reaction force components, and electromyography (EMG) were measured in all conditions. Results Post-intervention data indicated a significant decrease across time in the habituation SBR for EMG activity of the tibialis anterior (TA) in the pre-activation and absorptive phase of running (P<0.001). A significant increase was denoted in the pre-activation amplitude of the gastrocnemius (GAS) between the shod running, unhabituated SBR, and habituated SBR. Six weeks of SBR was associated with a significant decrease in the loading rates and impact forces. Additionally, SBR significantly decrease the stride length, step duration, and flight time, and stride frequency was significantly higher compared to shod running. Conclusions The findings of this study indicate that changes in motor patterns in previously habitually shod runners are possible and can be accomplished within 6 weeks. Non-habituation SBR did not show a significant neuromuscular adaptation in the EMG activity of TA and GAS as manifested after 6 weeks of habituated SBR. PMID:26166443

Influence of anthropometry on race performance in extreme endurance triathletes: World Challenge Deca Iron Triathlon 2006

PubMed Central

Knechtle, Beat; Knechtle, Patrizia; Andonie, Jorge Luis; Kohler, Götz

2007-01-01

Objective To investigate the influence of anthropometric variables on race performance in ultra‐endurance triathletes in an ultra‐triathlon. Design Descriptive field study. Setting The “World Challenge Deca Iron Triathlon 2006” in Monterrey, Mexico, in which everyday for 10 consecutive days athletes had to perform the distance of one Ironman triathlon of 3.8 km swimming, 180 km cycling and 42.195 km running. Subjects Eight male ultra‐endurance athletes (mean (SD) age 40.6 (10.7) years, weight 76.4 (8.4) kg, height 175 (4) cm and body mass index (BMI) 24.7 (2.2) kg/m2). Interventions None. Main outcome measures Direct measurement of body mass, height, leg length, skinfold thicknesses, limb circumference and calculation of BMI, skeletal muscle mass (SM), percentage SM (%SM) and percentage body fat (%BF) in order to correlate measured and calculated anthropometric variables with race performance. Results Race time was not significantly (p>0.05) influenced by the directly measured variables, height, leg length, body mass, average skinfold thicknesses, or circumference of thigh, calf or upper arm. Furthermore, no significant (p>0.05) correlation was observed between race time and the calculated variables, BMI, %SM and %BF. Conclusions In a multistage ultra‐triathlon over 10 Ironman triathlon distances in 10 consecutive days, there was no effect of body mass, height, leg length, skinfold thicknesses, limb circumference, BMI, %SM or %BF on race performance in the only eight finishers. PMID:17556527

A Comparison of the Energetic Cost of Running in Marathon Racing Shoes.

PubMed

Hoogkamer, Wouter; Kipp, Shalaya; Frank, Jesse H; Farina, Emily M; Luo, Geng; Kram, Rodger

2018-04-01

Reducing the energetic cost of running seems the most feasible path to a sub-2-hour marathon. Footwear mass, cushioning, and bending stiffness each affect the energetic cost of running. Recently, prototype running shoes were developed that combine a new highly compliant and resilient midsole material with a stiff embedded plate. The aim of this study was to determine if, and to what extent, these newly developed running shoes reduce the energetic cost of running compared with established marathon racing shoes. 18 high-caliber athletes ran six 5-min trials (three shoes × two replicates) in prototype shoes (NP), and two established marathon shoes (NS and AB) during three separate sessions: 14, 16, and 18 km/h. We measured submaximal oxygen uptake and carbon dioxide production during minutes 3-5 and averaged energetic cost (W/kg) for the two trials in each shoe model. Compared with the established racing shoes, the new shoes reduced the energetic cost of running in all 18 subjects tested. Averaged across all three velocities, the energetic cost for running in the NP shoes (16.45 ± 0.89 W/kg; mean ± SD) was 4.16 and 4.01% lower than in the NS and AB shoes, when shoe mass was matched (17.16 ± 0.92 and 17.14 ± 0.97 W/kg, respectively, both p < 0.001). The observed percent changes were independent of running velocity (14-18 km/h). The prototype shoes lowered the energetic cost of running by 4% on average. We predict that with these shoes, top athletes could run substantially faster and achieve the first sub-2-hour marathon.

EFFECTS OF FOREFOOT RUNNING ON CHRONIC EXERTIONAL COMPARTMENT SYNDROME: A CASE SERIES

PubMed Central

Gregory, Robert; Alitz, Curtis; Gerber, J. Parry

2011-01-01

Introduction: Chronic exertional compartment syndrome (CECS) is a condition that occurs almost exclusively with running whereby exercise increases intramuscular pressure compromising circulation, prohibiting muscular function, and causing pain in the lower leg. Currently, a lack of evidence exists for the effective conservative management of CECS. Altering running mechanics by adopting forefoot running as opposed to heel striking may assist in the treatment of CECS, specifically with anterior compartment symptoms. Case Description: The purpose of this case series is to describe the outcomes for subjects with CECS through a systematic conservative treatment model focused on forefoot running. Subject one was a 21 y/o female with a 4 year history of CECS and subject two was a 21 y/o male, 7 months status-post two-compartment right leg fasciotomy with a return of symptoms and a new onset of symptoms on the contralateral side. Outcome: Both subjects modified their running technique over a period of six weeks. Kinematic and kinetic analysis revealed increased step rate while step length, impulse, and peak vertical ground reaction forces decreased. In addition, leg intracompartmental pressures decreased from pre-training to post-training. Within 6 weeks of intervention subjects increased their running distance and speed absent of symptoms of CECS. Follow-up questionnaires were completed by the subjects at 7 months following intervention; subject one reported running distances up to 12.87 km pain-free and subject two reported running 6.44 km pain-free consistently 3 times a week. Discussion: This case series describes a potentially beneficial conservative management approach to CECS in the form of forefoot running instruction. Further research in this area is warranted to further explore the benefits of adopting a forefoot running technique for CECS as well as other musculoskeletal overuse complaints. PMID:22163093

Effects of forefoot running on chronic exertional compartment syndrome: a case series.

PubMed

Diebal, Angela R; Gregory, Robert; Alitz, Curtis; Gerber, J Parry

2011-12-01

Chronic exertional compartment syndrome (CECS) is a condition that occurs almost exclusively with running whereby exercise increases intramuscular pressure compromising circulation, prohibiting muscular function, and causing pain in the lower leg. Currently, a lack of evidence exists for the effective conservative management of CECS. Altering running mechanics by adopting forefoot running as opposed to heel striking may assist in the treatment of CECS, specifically with anterior compartment symptoms. The purpose of this case series is to describe the outcomes for subjects with CECS through a systematic conservative treatment model focused on forefoot running. Subject one was a 21 y/o female with a 4 year history of CECS and subject two was a 21 y/o male, 7 months status-post two-compartment right leg fasciotomy with a return of symptoms and a new onset of symptoms on the contralateral side. Both subjects modified their running technique over a period of six weeks. Kinematic and kinetic analysis revealed increased step rate while step length, impulse, and peak vertical ground reaction forces decreased. In addition, leg intracompartmental pressures decreased from pre-training to post-training. Within 6 weeks of intervention subjects increased their running distance and speed absent of symptoms of CECS. Follow-up questionnaires were completed by the subjects at 7 months following intervention; subject one reported running distances up to 12.87 km pain-free and subject two reported running 6.44 km pain-free consistently 3 times a week. This case series describes a potentially beneficial conservative management approach to CECS in the form of forefoot running instruction. Further research in this area is warranted to further explore the benefits of adopting a forefoot running technique for CECS as well as other musculoskeletal overuse complaints.

Differences in kinetic asymmetry between injured and noninjured novice runners: a prospective cohort study.

PubMed

Bredeweg, S W; Buist, I; Kluitenberg, B

2013-09-01

The purpose of this prospective study was to describe natural levels of asymmetry in running, compare levels of asymmetry between injured and noninjured novice runners and compare kinetic variables between the injured and noninjured lower limb within the novice runners with an injury. At baseline vertical ground reaction forces and symmetry angles (SA) were assessed with an instrumented treadmill equipped with three force measuring transducers. Female participants ran at 8 and 9 km h(-1) and male runners ran at 9 and 10 km h(-1). Participants were novice female and male recreational runners and were followed during a 9-week running program. Two hundred and ten novice runners enrolled this study, 133 (63.3%) female and 77 (36.7%) male runners. Thirty-four runners reported an RRI. At baseline SA values varied widely for all spatio-temporal and kinetic variables. The inter-individual differences in SA were also high. No significant differences in SA were found between female and male runners running at 9 km h(-1). In injured runners the SA of the impact peak was significantly lower compared to noninjured runners. Natural levels of asymmetry in running were high. The SA of impact peak in injured runners was lower compared to noninjured runners and no differences were seen between the injured and noninjured lower limbs. Copyright © 2013 Elsevier B.V. All rights reserved.

Medical considerations in triathlon competition: recommendations for triathlon organisers, competitors and coaches.

PubMed

Dallam, George M; Jonas, Steven; Miller, Thomas K

2005-01-01

Competitors in triathlons experience a range of environmental conditions and physiological demands in excess of that found in individual sport events of comparable duration. Consequently, there is a broad range of possible medical problems and complications that must be taken into account when preparing for such races. For most competitors, an Olympic-distance triathlon typically takes between 2-4 hours to complete. This race begins with a swimming segment of 1500 m. Given the wide variety of race venues found around the world, these swims occur in an assortment of water temperatures (from warm to cold) and conditions (from ocean surf to lake calm). Swimmers often exit the water in a state of moderate dehydration and hypothermia and then immediately start the 40 km cycling leg. Many do so in their swimming attire. A wide variety of road surfaces, technically challenging topography, variable environmental conditions and dramatically changing velocities can be encountered on the cycle course. The race concludes with a 10 km running leg. Since it is the final leg, it is often completed in higher ambient temperatures than those encountered at the start, with the athlete possibly running in a significant state of dehydration and fatigue. Other medical problems commonly encountered in triathlon include: muscle cramping, heat illness, postural hypotension, excessive exposure to ultraviolet radiation, musculoskeletal injuries and trauma, gastrointestinal problems as well as post-race bacterial infection, immunosuppression, sympathetic nervous system and psychological exhaustion, and haemolysis. The rate of occurrence of such events and the severity of their potentially negative outcomes is a function of the methods used by both the race organisers and the competitors to prevent or respond to the conditions imposed by the race. Triathletes also commonly compete in both shorter 'sprint distance' events (in the range of a 0.75 km swim, 20 km cycle and 5 km run) and longer events including both one-half and full Ironman distances (2.5 and 3.8 km swim, 80 and 180 km cycle, 20 and 42 km run, respectively), as well as ultra-distance events that exceed the Ironman distance. In the longer events, the previously mentioned medical considerations are further magnified and additional considerations such as hyponatraemia can also occur. Reducing risk associated with these concerns is accomplished by: taking into account weather and water temperature/conditions data prior to event scheduling; effective swim, cycle and run course organisation and management; environmental monitoring prior to and during the event; the implementation of a water safety plan; provision of appropriate fluid replacement throughout the course; implementation of helmet use and non-drafting regulations in the cycling leg; and competitor knowledge regarding fluid replacement, biomechanical technique, physical preparation, safe equipment and course familiarity. Despite these concerns, triathlon participation appears to relatively safe for persons of all ages, assuming that high-risk adults undertake health screening.

Changes in Cartilage Biomarker Levels During a Transcontinental Multistage Footrace Over 4486 km.

PubMed

Mündermann, Annegret; Klenk, Christopher; Billich, Christian; Nüesch, Corina; Pagenstert, Geert; Schmidt-Trucksäss, Arno; Schütz, Uwe

2017-09-01

Cartilage turnover and load-induced tissue changes are frequently assessed by quantifying concentrations of cartilage biomarkers in serum. To date, information on the effects of ultramarathon running on articular cartilage is scarce. Serum concentrations of cartilage oligomeric matrix protein (COMP), matrix metalloproteinase (MMP)-1, MMP-3, MMP-9, COL2-3/4C long mono (C2C), procollagen type II C-terminal propeptide (CPII), and C2C:CPII will increase throughout a multistage ultramarathon. Descriptive laboratory study. Blood samples were collected from 36 runners (4 female; mean age, 49.0 ± 10.7 years; mean body mass index, 23.1 ± 2.3 kg/m 2 [start] and 21.4 ± 1.9 kg/m 2 [finish]) before (t 0 ) and during (t 1 : 1002 km; t 2 : 2132 km; t 3 : 3234 km; t 4 : 4039 km) a 4486-km multistage ultramarathon. Serum COMP, MMP-1, MMP-3, MMP-9, C2C, and CPII levels were assessed using commercial enzyme-linked immunosorbent assays. Linear mixed models were used to detect significant changes in serum biomarker levels over time with the time-varying covariates of body weight, running speed, and daily running time. Serum concentrations of COMP, MMP-9, and MMP-3 changed significantly throughout the multistage ultramarathon. On average, concentrations increased during the first measurement interval (MI1: t 1 -t 0 ) by 22.5% for COMP (95% CI, 0.29-0.71 ng/mL), 22.3% for MMP-3 (95% CI, 0.24-15.37 ng/mL), and 95.6% for MMP-9 (95% CI, 81.7-414.5 ng/mL) and remained stable throughout MI2, MI3, and MI4. Serum concentrations of MMP-1, C2C, CPII, and C2C:CPII did not change significantly throughout the multistage ultramarathon. Changes in MMP-3 were statistically associated with changes in COMP throughout the ultramarathon race (MMP-3: Wald Z = 3.476, P = .001). Elevated COMP levels indicate increased COMP turnover in response to extreme running, and the association between load-induced changes in MMP-3 and changes in COMP suggests the possibility that MMP-3 may be involved in the degradation of COMP. These results suggest that articular cartilage is able to adapt even to extreme physical activity, possibly explaining why the risk of degenerative joint disease is not elevated in the running population.

Comparison of systemic cytokine responses after a long distance triathlon and a 100-km run: relationship to metabolic and inflammatory processes.

PubMed

Gomez-Merino, Danielle; Drogou, Catherine; Guezennec, Charles Yannick; Burnat, Pascal; Bourrilhon, Cyprien; Tomaszewski, Armand; Milhau, Stéphane; Chennaoui, Mounir

2006-06-01

Suggested mechanisms for the systemic, circulating cytokinemia observed during heavy physical exertion include inflammation and energy demand. We compared cytokine levels and examined the underlying physiological mechanisms between a long-distance triathlon and a 100-km run, two endurance races of similar duration but characterized by differences in muscle strain. Blood samples were collected from 12 triathletes (34.8 +/- 1.4 yr) and 11 runners (42.4 +/- 2.2 yr) the day before and at the end of races (T1, R1), and 24 h and 7 days post-race (R2, R3). At R1, significant race-related differences were observed, with greater increases in plasma levels of interleukins (IL)-6, IL-1ra, and IL-10 in the triathletes than in the runners, while levels of the chemokine IL-8 increased solely in the runners (P < 0.05, P < 0.05, P < 0.01, and P < 0.001, respectively). At R1, free fatty acid (FFA) levels were 119% higher in the triathletes than in the runners, who were the most liable to muscle damage in view of increased levels of the muscle-specific enzyme, creatine kinase (CK), loss of muscle flexibility and decreased physical performance. At R1, levels of heat shock protein (HSP)72 increased in the two groups but were 173% higher in the runners. For the two groups, all parameters had returned to pre-race levels by seven days post-race. Positive correlations were noted between IL-6 and FFA in the triathletes and between IL-8 and CK and HSP72 in the runners. The differences between cytokine responses after a long distance triathlon and a 100-km run suggested that IL-6 and IL-8 could be employed as respective markers of the intensity of the muscular activity required for substrate availability and vascular inflammation.

Applied physiology of marathon running.

PubMed

Sjödin, B; Svedenhag, J

1985-01-01

Performance in marathon running is influenced by a variety of factors, most of which are of a physiological nature. Accordingly, the marathon runner must rely to a large extent on a high aerobic capacity. But great variations in maximal oxygen uptake (VO2 max) have been observed among runners with a similar performance capacity, indicating complementary factors are of importance for performance. The oxygen cost of running or the running economy (expressed, e.g. as VO2 15 at 15 km/h) as well as the fractional utilisation of VO2 max at marathon race pace (%VO2 Ma X VO2 max-1) [where Ma = mean marathon velocity] are additional factors which are known to affect the performance capacity. Together VO2 max, VO2 15 and %VO2 Ma X VO2 max-1 can almost entirely explain the variation in marathon performance. To a similar degree, these variables have also been found to explain the variations in the 'anaerobic threshold'. This factor, which is closely related to the metabolic response to increasing exercise intensities, is the single variable that has the highest predictive power for marathon performance. But a major limiting factor to marathon performance is probably the choice of fuels for the exercising muscles, which factor is related to the %VO2 Ma X VO2 max-1. Present indications are that marathon runners, compared with normal individuals, have a higher turnover rate in fat metabolism at given high exercise intensities expressed both in absolute (m/sec) and relative (%VO2 max) terms. The selection of fat for oxidation by the muscles is important since the stores of the most efficient fuel, the carbohydrates, are limited. The large amount of endurance training done by marathon runners is probably responsible for similar metabolic adaptations, which contribute to a delayed onset of fatigue and raise the VO2 Ma X VO2max-1. There is probably an upper limit in training kilometrage above which there are no improvements in the fractional utilisation of VO2 max at the marathon race pace. The influence of training on VO2 max and, to some extent, on the running economy appears, however, to be limited by genetic factors.

Inverse and Forward Modeling of The 2014 Iquique Earthquake with Run-up Data

NASA Astrophysics Data System (ADS)

Fuentes, M.

2015-12-01

The April 1, 2014 Mw 8.2 Iquique earthquake excited a moderate tsunami which turned on the national alert of tsunami threat. This earthquake was located in the well-known seismic gap in northern Chile which had a high seismic potential (~ Mw 9.0) after the two main large historic events of 1868 and 1877. Nonetheless, studies of the seismic source performed with seismic data inversions suggest that the event exhibited a main patch located around 19.8° S at 40 km of depth with a seismic moment equivalent to Mw = 8.2. Thus, a large seismic deficit remains in the gap being capable to release an event of Mw = 8.8-8.9. To understand the importance of the tsunami threat in this zone, a seismic source modeling of the Iquique Earthquake is performed. A new approach based on stochastic k2 seismic sources is presented. A set of those sources is generated and for each one, a full numerical tsunami model is performed in order to obtain the run-up heights along the coastline. The results are compared with the available field run-up measurements and with the tide gauges that registered the signal. The comparison is not uniform; it penalizes more when the discrepancies are larger close to the peak run-up location. This criterion allows to identify the best seismic source from the set of scenarios that explains better the observations from a statistical point of view. By the other hand, a L2 norm minimization is used to invert the seismic source by comparing the peak nearshore tsunami amplitude (PNTA) with the run-up observations. This method searches in a space of solutions the best seismic configuration by retrieving the Green's function coefficients in order to explain the field measurements. The results obtained confirm that a concentrated down-dip patch slip adequately models the run-up data.

Locomotion characteristics and match-induced impairments in physical performance in male elite team handball players.

PubMed

Michalsik, L B; Aagaard, P; Madsen, K

2013-07-01

The purpose of this study was to determine the physical demands and match-induced impairments in physical performance in male elite Team Handball (TH) players in relation to playing position. Male elite TH field players were closely observed during 6 competitive seasons. Each player (wing players: WP, pivots: PV, backcourt players: BP) was evaluated during match-play using video recording and subsequently performing locomotion match analysis. A total distance of 3 627±568 m (group means±SD) was covered per match with a total effective playing time (TPT) of 53:51±5:52 min:s, while full-time players covered 3 945±538 m. The mean speed was 6.40±1.01 km · h - 1. High-intensity running constituted only 1.7±0.9% of TPT per match corresponding to 7.9±4.9% of the total distance covered. An average of 1 482.4±312.6 activity changes per player (n=82) with 53.2±14.1 high-intensity runs were observed per match. Total distance covered was greater in BP (3 765±532 m) and WP (3 641±501 m) than PV (3 295±495 m) (p<0.05), and WP performed more high-intensity running (10.9±5.7% of total distance covered) than PV (8.5±4.3%, p<0.05) and BP (6.2±3.2%, p<0.01). The amount of high-intensity running was lower (p<0.05) in the second (130.4±38.4 m) than in the first half (155.3±47.6 m) corresponding to a decrease of 16.2%.In conclusion, modern male elite TH is a complex team sport that comprises several types of movement categories, which during match-play place moderate-to-high demands on intermittent endurance running capacity and where the amount of high-intensity running may be high during brief periods of the match. Signs of fatigue-related changes were observed in terms of temporary impaired physical performance, since the amount of high-intensity running was reduced in the second half. Notably, physical demands differed between playing positions, with WP demonstrating a more intensive activity pattern than BP and PV, respectively. © Georg Thieme Verlag KG Stuttgart · New York.

Assessment of the Suitability of High Resolution Numerical Weather Model Outputs for Hydrological Modelling in Mountainous Cold Regions

NASA Astrophysics Data System (ADS)

Rasouli, K.; Pomeroy, J. W.; Hayashi, M.; Fang, X.; Gutmann, E. D.; Li, Y.

2017-12-01

The hydrology of mountainous cold regions has a large spatial variability that is driven both by climate variability and near-surface process variability associated with complex terrain and patterns of vegetation, soils, and hydrogeology. There is a need to downscale large-scale atmospheric circulations towards the fine scales that cold regions hydrological processes operate at to assess their spatial variability in complex terrain and quantify uncertainties by comparison to field observations. In this research, three high resolution numerical weather prediction models, namely, the Intermediate Complexity Atmosphere Research (ICAR), Weather Research and Forecasting (WRF), and Global Environmental Multiscale (GEM) models are used to represent spatial and temporal patterns of atmospheric conditions appropriate for hydrological modelling. An area covering high mountains and foothills of the Canadian Rockies was selected to assess and compare high resolution ICAR (1 km × 1 km), WRF (4 km × 4 km), and GEM (2.5 km × 2.5 km) model outputs with station-based meteorological measurements. ICAR with very low computational cost was run with different initial and boundary conditions and with finer spatial resolution, which allowed an assessment of modelling uncertainty and scaling that was difficult with WRF. Results show that ICAR, when compared with WRF and GEM, performs very well in precipitation and air temperature modelling in the Canadian Rockies, while all three models show a fair performance in simulating wind and humidity fields. Representation of local-scale atmospheric dynamics leading to realistic fields of temperature and precipitation by ICAR, WRF, and GEM makes these models suitable for high resolution cold regions hydrological predictions in complex terrain, which is a key factor in estimating water security in western Canada.

Changes in running kinematics, kinetics, and spring-mass behavior over a 24-h run.

PubMed

Morin, Jean-Benoît; Samozino, Pierre; Millet, Guillaume Y

2011-05-01

This study investigated the changes in running mechanics and spring-mass behavior over a 24-h treadmill run (24TR). Kinematics, kinetics, and spring-mass characteristics of the running step were assessed in 10 experienced ultralong-distance runners before, every 2 h, and after a 24TR using an instrumented treadmill dynamometer. These measurements were performed at 10 km·h, and mechanical parameters were sampled at 1000 Hz for 10 consecutive steps. Contact and aerial times were determined from ground reaction force (GRF) signals and used to compute step frequency. Maximal GRF, loading rate, downward displacement of the center of mass, and leg length change during the support phase were determined and used to compute both vertical and leg stiffness. Subjects' running pattern and spring-mass behavior significantly changed over the 24TR with a 4.9% higher step frequency on average (because of a significantly 4.5% shorter contact time), a lower maximal GRF (by 4.4% on average), a 13.0% lower leg length change during contact, and an increase in both leg and vertical stiffness (+9.9% and +8.6% on average, respectively). Most of these changes were significant from the early phase of the 24TR (fourth to sixth hour of running) and could be speculated as contributing to an overall limitation of the potentially harmful consequences of such a long-duration run on subjects' musculoskeletal system. During a 24TR, the changes in running mechanics and spring-mass behavior show a clear shift toward a higher oscillating frequency and stiffness, along with lower GRF and leg length change (hence a reduced overall eccentric load) during the support phase of running. © 2011 by the American College of Sports Medicine

Mature thunderstorm cloud top structure - Three-dimensional numerical simulation versus satellite observations

NASA Technical Reports Server (NTRS)

Schlesinger, R. E.

1982-01-01

Preliminary results of four runs with a three-dimensional model of the effects of vertical wind shear on cloud top height/temperature structure and the internal properties of isolate midlatitude thunderstorms are reported. The model is being developed as an aid to analyses of GEO remote sensing satellite data. The grid is a 27 x 27 x 20 mesh with 2 km horizontal resolution and 0.9 vertical resolution. The total grid is 54 km on a side and 18 km deep. A second-order Crowley scheme for advecting momentum is extended with a third-order correction for spatial truncation error, and the earth-relative horizontal surface wind components are decreased to 50 percent of their values at 0.45 km. A temperature increase with height is included, together with an initial impulse consisting of a nonrotating cylindrical weak buoyant updraft 10 km in radius. The results of the runs are discussed in terms of the time variation of the vertical velocity extrema, the effects of strong and weak shear on a storm, the cloud top height, the Lagrangian dynamics of a thermal couplet, and data from a real storm.

12 weeks of simulated barefoot running changes foot-strike patterns in female runners.

PubMed

McCarthy, C; Fleming, N; Donne, B; Blanksby, B

2014-05-01

To investigate the effect of a transition program of simulated barefoot running (SBR) on running kinematics and foot-strike patterns, female recreational athletes (n=9, age 29 ± 3 yrs) without SBR experience gradually increased running distance in Vibram FiveFingers SBR footwear over 12 weeks. Matched controls (n=10, age 30 ± 4 yrs) continued running in standard footwear. A 3-D motion analysis of treadmill running at 12 km/h(-1) was performed by both groups, barefoot and shod, pre- and post-intervention. Post-intervention data indicated a more-forefoot strike pattern in the SBR group compared to controls; both running barefoot (P>0.05), and shod (P<0.001). When assessed barefoot, there were significant kinematic differences across time in the SBR group for ankle flexion angle at toe-off (P<0.01). When assessed shod, significant kinematic changes occurred across time, for ankle flexion angles at foot-strike (P<0.001) and toe-off (P<0.01), and for range of motion (ROM) in the absorptive phase of stance (P<0.01). A knee effect was recorded in the SBR group for flexion ROM in the absorptive phase of stance (P<0.05). No significant changes occurred in controls. Therefore, a 12-week transition program in SBR could assist athletes seeking a more-forefoot strike pattern and "barefoot" kinematics, regardless of preferred footwear. © Georg Thieme Verlag KG Stuttgart · New York.

Can Pacing Be Regulated by Post-Activation Potentiation? Insights from a Self-Paced 30 km Trial in Half-Marathon Runners

PubMed Central

Del Rosso, Sebastián; Barros, Edilberto; Tonello, Laís; Oliveira-Silva, Iransé; Behm, David G.; Foster, Carl; Boullosa, Daniel A.

2016-01-01

Purpose Given the co-existence of post-activation potentiation (PAP) and fatigue within muscle, it is not known whether PAP could influence performance and pacing during distance running by moderating fatigue. The aim of this study was to assess the influence of PAP on pacing, jumping and other physiological measures during a self-paced 30 km trial. Methods Eleven male endurance-trained runners (half-marathon runners) volunteered to participate in this study. Runners participated in a multi-stage 30 km trial. Before the trial started, determination of baseline blood lactate (bLa) and countermovement jump (CMJ) height was performed. The self-paced 30 km trial consisted of 6 × 5 km splits. At the end of each 5 km split (60 s break), data on time to complete the split, CMJ height, Rating of Perceived Exertion (RPE) and blood lactate were collected while heart rate was continuously monitored. Results There was a significant decrease in speed (e.g. positive pacing strategy after the 4th split, p<0.05) with a progressive increase in RPE throughout the trial. Compared with baseline, CMJ height was significantly (p<0.05) greater than baseline and was maintained until the end of the trial with an increase after the 5th split, concomitant with a significant reduction in speed and an increase in RPE. Significant correlations were found between ΔCMJ and ΔSPEED (r = 0.77 to 0.87, p<0.05) at different time points as well as between RPE and speed (r = -0.61 to -0.82, p<0.05). Conclusion Our results indicates that fatigue and potentiation co-exist during long lasting endurance events, and that the observed increase in jump performance towards the end of the trial could be reflecting a greater potentiation potentially perhaps counteracting the effects of fatigue and preventing further reductions in speed. PMID:26934357

Influence of speed and step frequency during walking and running on motion sensor output.

PubMed

Rowlands, Ann V; Stone, Michelle R; Eston, Roger G

2007-04-01

Studies have reported strong linear relationships between accelerometer output and walking/running speeds up to 10 km x h(-1). However, ActiGraph uniaxial accelerometer counts plateau at higher speeds. The aim of this study was to determine the relationships of triaxial accelerometry, uniaxial accelerometry, and pedometry with speed and step frequency (SF) across a range of walking and running speeds. Nine male runners wore two ActiGraph uniaxial accelerometers, two RT3 triaxial accelerometers (all set at a 1-s epoch), and two Yamax pedometers. Each participant walked for 60 s at 4 and 6 km x h(-1), ran for 60 s at 10, 12, 14, 16, and 18 km x h(-1), and ran for 30 s at 20, 22, 24, and 26 km x h(-1). Step frequency was recorded by a visual count. ActiGraph counts peaked at 10 km x h(-10 (2.5-3.0 Hz SF) and declined thereafter (r=0.02, P>0.05). After correction for frequency-dependent filtering, output plateaued at 10 km x h(-1) but did not decline (r=0.77, P<0.05). Similarly, RT3 vertical counts plateaued at speeds > 10 km x h(-1) (r=0.86, P<0.01). RT3 vector magnitude and anteroposterior and mediolateral counts maintained a linear relationship with speed (r>0.96, P<0.001). Step frequency assessed by pedometry compared well with actual step frequency up to 20 km x h(-1) (approximately 3.5 Hz) but then underestimated actual steps (Yamax r=0.97; ActiGraph pedometer r=0.88, both P<0.001). Increasing underestimation of activity by the ActiGraph as speed increases is related to frequency-dependent filtering and assessment of acceleration in the vertical plane only. RT3 vector magnitude was strongly related to speed, reflecting the predominance of horizontal acceleration at higher speeds. These results indicate that high-intensity activity is underestimated by the ActiGraph, even after correction for frequency-dependent filtering, but not by the RT3. Pedometer output is highly correlated with step frequency.

A Tool for Modelling the Probability of Landslides Impacting Road Networks

NASA Astrophysics Data System (ADS)

Taylor, Faith E.; Santangelo, Michele; Marchesini, Ivan; Malamud, Bruce D.; Guzzetti, Fausto

2014-05-01

Triggers such as earthquakes or heavy rainfall can result in hundreds to thousands of landslides occurring across a region within a short space of time. These landslides can in turn result in blockages across the road network, impacting how people move about a region. Here, we show the development and application of a semi-stochastic model to simulate how landslides intersect with road networks during a triggered landslide event. This was performed by creating 'synthetic' triggered landslide inventory maps and overlaying these with a road network map to identify where road blockages occur. Our landslide-road model has been applied to two regions: (i) the Collazzone basin (79 km2) in Central Italy where 422 landslides were triggered by rapid snowmelt in January 1997, (ii) the Oat Mountain quadrangle (155 km2) in California, USA, where 1,350 landslides were triggered by the Northridge Earthquake (M = 6.7) in January 1994. For both regions, detailed landslide inventory maps for the triggered events were available, in addition to maps of landslide susceptibility and road networks of primary, secondary and tertiary roads. To create 'synthetic' landslide inventory maps, landslide areas (AL) were randomly selected from a three-parameter inverse gamma probability density function, consisting of a power law decay of about -2.4 for medium and large values of AL and an exponential rollover for small values of AL. The number of landslide areas selected was based on the observed density of landslides (number of landslides km-2) in the triggered event inventories. Landslide shapes were approximated as ellipses, where the ratio of the major and minor axes varies with AL. Landslides were then dropped over the region semi-stochastically, conditioned by a landslide susceptibility map, resulting in a synthetic landslide inventory map. The originally available landslide susceptibility maps did not take into account susceptibility changes in the immediate vicinity of roads, therefore our landslide susceptibility map was adjusted to further reduce the susceptibility near each road based on the road level (primary, secondary, tertiary). For each model run, we superimposed the spatial location of landslide drops with the road network, and recorded the number, size and location of road blockages recorded, along with landslides within 50 and 100 m of the different road levels. Network analysis tools available in GRASS GIS were also applied to measure the impact upon the road network in terms of connectivity. The model was performed 100 times in a Monte-Carlo simulation for each region. Initial results show reasonable agreement between model output and the observed landslide inventories in terms of the number of road blockages. In Collazzone (length of road network = 153 km, landslide density = 5.2 landslides km-2), the median number of modelled road blockages over 100 model runs was 5 (±2.5 standard deviation) compared to the mapped inventory observed number of 5 road blockages. In Northridge (length of road network = 780 km, landslide density = 8.7 landslides km-2), the median number of modelled road blockages over 100 model runs was 108 (±17.2 standard deviation) compared to the mapped inventory observed number of 48 road blockages. As we progress with model development, we believe this semi-stochastic modelling approach will potentially aid civil protection agencies to explore different scenarios of road network potential damage as the result of different magnitude landslide triggering event scenarios.

Effects of dietary antioxidants on training and performance in female runners.

PubMed

Braakhuis, Andrea J; Hopkins, Will G; Lowe, Tim E

2014-01-01

Exercise-induced oxidative stress is implicated in muscle damage and fatigue which has led athletes to embark on antioxidant supplementation regimes to negate these effects. This study investigated the intake of vitamin C (VC) (1 g), blackcurrant (BC) juice (15 mg VC, 300 mg anthocyanins) and placebo in isocaloric drink form on training progression, incremental running test and 5-km time-trial performance. Twenty-three trained female runners (age, 31 ± 8 y; mean ± SD) completed three blocks of high-intensity training for 3 wks and 3 days, separated by a washout (~3.7 wks). Changes in training and performance with each treatment were analysed with a mixed linear model, adjusting for performance at the beginning of each training block. Markers of oxidative status included protein carbonyl, malondialdehyde (in plasma and in vitro erythrocytes), ascorbic acid, uric acid and erythrocyte enzyme activity of superoxide dismutase, catalase and glutathione peroxidase were analysed. There was a likely harmful effect on mean running speed during training when taking VC (1.3%; 90% confidence limits ±1.3%). Effects of the two treatments relative to placebo on mean performance in the incremental test and time trial were unclear, but runners faster by 1 SD of peak speed demonstrated a possible improvement on peak running speed with BC juice (1.9%; ±2.5%). Following VC, certain oxidative markers were elevated: catalase at rest (23%; ±21%), protein carbonyls at rest (27%; ±38%) and superoxide dismutase post-exercise (8.3%; ±9.3%). In conclusion, athletes should be cautioned about taking VC chronically, however, BC may improve performance in the elite.

A Multi-Season Study of the Effects of MODIS Sea-Surface Temperatures on Operational WRF Forecasts at NWS Miami, FL

NASA Technical Reports Server (NTRS)

Case, Jonathan L.; Santos, Pablo; Lazarus, Steven M.; Splitt, Michael E.; Haines, Stephanie L.; Dembek, Scott R.; Lapenta, William M.

2008-01-01

Studies at the Short-term Prediction Research and Transition (SPORT) Center have suggested that the use of Moderate Resolution Imaging Spectroradiometer (MODIS) sea-surface temperature (SST) composites in regional weather forecast models can have a significant positive impact on short-term numerical weather prediction in coastal regions. Recent work by LaCasse et al (2007, Monthly Weather Review) highlights lower atmospheric differences in regional numerical simulations over the Florida offshore waters using 2-km SST composites derived from the MODIS instrument aboard the polar-orbiting Aqua and Terra Earth Observing System satellites. To help quantify the value of this impact on NWS Weather Forecast Offices (WFOs), the SPORT Center and the NWS WFO at Miami, FL (MIA) are collaborating on a project to investigate the impact of using the high-resolution MODIS SST fields within the Weather Research and Forecasting (WRF) prediction system. The project's goal is to determine whether more accurate specification of the lower-boundary forcing within WRF will result in improved land/sea fluxes and hence, more accurate evolution of coastal mesoscale circulations and the associated sensible weather elements. The NWS MIA is currently running WRF in real-time to support daily forecast operations, using the National Centers for Environmental Prediction Nonhydrostatic Mesoscale Model dynamical core within the NWS Science and Training Resource Center's Environmental Modeling System (EMS) software. Twenty-seven hour forecasts are run dally initialized at 0300, 0900, 1500, and 2100 UTC on a domain with 4-km grid spacing covering the southern half of Florida and adjacent waters of the Gulf of Mexico and Atlantic Ocean. Each model run is initialized using the Local Analysis and Prediction System (LAPS) analyses available in AWIPS. The SSTs are initialized with the NCEP Real-Time Global (RTG) analyses at 1/12deg resolution (approx.9 km); however, the RTG product does not exhibit fine-scale details consistent with its grid resolution. SPORT is conducting parallel WRF EMS runs identical to the operational runs at NWS MIA except for the use of MODIS SST composites in place of the RTG product as the initial and boundary conditions over water, The MODIS SST composites for initializing the SPORT WRF runs are generated on a 2-km grid four times daily at 0400, 0700, 1600, and 1900 UTC, based on the times of the overhead passes of the Aqua and Terra satellites. The incorporation of the MODIS SST data into the SPORT WRF runs is staggered such that SSTs are updated with a new composite every six hours in each of the WRF runs. From mid-February to July 2007, over 500 parallel WRF simulations have been collected for analysis and verification. This paper will present verification results comparing the NWS MIA operational WRF runs to the SPORT experimental runs, and highlight any substantial differences noted in the predicted mesoscale phenomena for specific cases.

Risk perception influences athletic pacing strategy.

PubMed

Micklewright, Dominic; Parry, David; Robinson, Tracy; Deacon, Greg; Renfree, Andrew; St Clair Gibson, Alan; Matthews, William J

2015-05-01

The objective of this study is to examine risk taking and risk perception associations with perceived exertion, pacing, and performance in athletes. Two experiments were conducted in which risk perception was assessed using the domain-specific risk taking (DOSPERT) scale in 20 novice cyclists (experiment 1) and 32 experienced ultramarathon runners (experiment 2). In experiment 1, participants predicted their pace and then performed a 5-km maximum effort cycling time trial on a calibrated Kingcycle mounted bicycle. Split times and perceived exertion were recorded every kilometer. In experiment 2, each participant predicted their split times before running a 100-km ultramarathon. Split times and perceived exertion were recorded at seven checkpoints. In both experiments, higher and lower risk perception groups were created using median split of DOSPERT scores. In experiment 1, pace during the first kilometer was faster among lower risk perceivers compared with higher risk perceivers (t(18) = 2.0, P = 0.03) and faster among higher risk takers compared with lower risk takers (t(18) = 2.2, P = 0.02). Actual pace was slower than predicted pace during the first kilometer in both the higher risk perceivers (t(9) = -4.2, P = 0.001) and lower risk perceivers (t(9) = -1.8, P = 0.049). In experiment 2, pace during the first 36 km was faster among lower risk perceivers compared with higher risk perceivers (t(16) = 2.0, P = 0.03). Irrespective of risk perception group, actual pace was slower than predicted pace during the first 18 km (t(16) = 8.9, P < 0.001) and from 18 to 36 km (t(16) = 4.0, P < 0.001). In both experiments, there was no difference in performance between higher and lower risk perception groups. Initial pace is associated with an individual's perception of risk, with low perceptions of risk being associated with a faster starting pace. Large differences between predicted and actual pace suggest that the performance template lacks accuracy, perhaps indicating greater reliance on momentary pacing decisions rather than preplanned strategy.

Prediction of half-marathon race time in recreational female and male runners.

PubMed

Knechtle, Beat; Barandun, Ursula; Knechtle, Patrizia; Zingg, Matthias A; Rosemann, Thomas; Rüst, Christoph A

2014-01-01

Half-marathon running is of high popularity. Recent studies tried to find predictor variables for half-marathon race time for recreational female and male runners and to present equations to predict race time. The actual equations included running speed during training for both women and men as training variable but midaxillary skinfold for women and body mass index for men as anthropometric variable. An actual study found that percent body fat and running speed during training sessions were the best predictor variables for half-marathon race times in both women and men. The aim of the present study was to improve the existing equations to predict half-marathon race time in a larger sample of male and female half-marathoners by using percent body fat and running speed during training sessions as predictor variables. In a sample of 147 men and 83 women, multiple linear regression analysis including percent body fat and running speed during training units as independent variables and race time as dependent variable were performed and an equation was evolved to predict half-marathon race time. For men, half-marathon race time might be predicted by the equation (r(2) = 0.42, adjusted r(2) = 0.41, SE = 13.3) half-marathon race time (min) = 142.7 + 1.158 × percent body fat (%) - 5.223 × running speed during training (km/h). The predicted race time correlated highly significantly (r = 0.71, p < 0.0001) to the achieved race time. For women, half-marathon race time might be predicted by the equation (r(2) = 0.68, adjusted r(2) = 0.68, SE = 9.8) race time (min) = 168.7 + 1.077 × percent body fat (%) - 7.556 × running speed during training (km/h). The predicted race time correlated highly significantly (r = 0.89, p < 0.0001) to the achieved race time. The coefficients of determination of the models were slightly higher than for the existing equations. Future studies might include physiological variables to increase the coefficients of determination of the models.

Oxidative Stress Assessment in Response to Ultraendurance Exercise: Thiols Redox Status and ROS Production according to Duration of a Competitive Race

PubMed Central

Vezzoli, Alessandra; Dellanoce, Cinzia; Montorsi, Michela; Tonini, Annamaria; Accinni, Roberto

2016-01-01

Purpose. Response to an ultraendurance competitive race on thiols redox status, reactive oxygen species (ROS) production, and oxidative stress (OxS) was investigated according to duration. Methods. Twenty-four elite runners were examined: six completed 50 km and eighteen 100 km. Blood and urine samples were collected before and immediately after the race. Erythrocytes and plasma aminothiols by high-performance liquid chromatography, total antioxidant capacity (TAC), and OxS biomarkers (protein carbonyl (PC), thiobarbituric acid-reactive substances (TBARS), 8-isoprostane (8-iso-PGF2α), and 8-OH-2-deoxyguanosine (8-OH-dG)) by immunoenzymatic assays and ROS production by Electron Paramagnetic Resonance were assessed. Results. Significant increases (P between <0.05 and <0.0001) were recorded in plasma total and oxidized aminothiols concentration and TAC (P < 0.0001) only after 100 km: plasmatic (ROS production (+12 versus +29%), PC (+54 versus +115%), and TBARS (+28 versus +55%)) and urinary (8-OH-dG.creatinine−1 (+71 versus +158%) and 8-iso-PGF2α.creatinine−1 (+43 versus +135%)) concentrations for 50 and 100 km (duration 4 h 3′ versus 8 h 42′), respectively. Conclusion. Very prolonged ultraendurance exercise causes an increase in ROS production and OxS depending on specific biomarker examined but always linearly and directly related to exercise duration. Redox status of erythrocytes was preserved. A relationship between running performance and both prerace ROS production and antioxidant-redox status was found in 100 km race. PMID:27504148

Overspeed HIIT in Lower-Body Positive Pressure Treadmill Improves Running Performance.

PubMed

Gojanovic, Boris; Shultz, Rebecca; Feihl, Francois; Matheson, Gordon

2015-12-01

Optimal high-intensity interval training (HIIT) regimens for running performance are unknown, although most protocols result in some benefit to key performance factors (running economy (RE), anaerobic threshold (AT), or maximal oxygen uptake (VO2max)). Lower-body positive pressure (LBPP) treadmills offer the unique possibility to partially unload runners and reach supramaximal speeds. We studied the use of LBPP to test an overspeed HIIT protocol in trained runners. Eleven trained runners (35 ± 8 yr, VO2max, 55.7 ± 6.4 mL·kg⁻¹·min⁻¹) were randomized to an LBPP (n = 6) or a regular treadmill (CON, n = 5), eight sessions over 4 wk of HIIT program. Four to five intervals were run at 100% of velocity at VO2max (vVO2max) during 60% of time to exhaustion at vVO2max (Tlim) with a 1:1 work:recovery ratio. Performance outcomes were 2-mile track time trial, VO2max, vVO2max, vAT, Tlim, and RE. LBPP sessions were carried out at 90% body weight. Group-time effects were present for vVO2max (CON, 17.5 vs. 18.3, P = 0.03; LBPP, 19.7 vs. 22.3 km·h⁻¹; P < 0.001) and Tlim (CON, 307.0 vs. 404.4 s, P = 0.28; LBPP, 444.5 vs. 855.5, P < 0.001). Simple main effects for time were present for field performance (CON, -18; LBPP, -25 s; P = 0.002), VO2max (CON, 57.6 vs. 59.6; LBPP, 54.1 vs. 55.1 mL·kg⁻¹·min⁻¹; P = 0.04) and submaximal HR (157.7 vs. 154.3 and 151.4 vs. 148.5 bpm; P = 0.002). RE was unchanged. A 4-wk HIIT protocol at 100% vVO2max improves field performance, vVO2max, VO2max and submaximal HR in trained runners. Improvements are similar if intervals are run on a regular treadmill or at higher speeds on a LPBB treadmill with 10% body weight reduction. LBPP could provide an alternative for taxing HIIT sessions.

Plasma lactate accumulation and distance running performance. 1979.

PubMed

Farrell, P A; Wilmore, J H; Coyle, E F; Billing, J E; Costill, D L

1993-10-01

Laboratory and field assessments were made on eighteen male distance runners. Performance data were obtained for distances of 3.2, 9.7, 15, 19.3 km (n = 18) and the marathon (n = 13). Muscle fiber composition expressed as percent of slow twitch fibers (%ST), maximal oxygen consumption (VO2max), running economy (VO2 for a treadmill velocity of 268 m/min), and the VO2 and treadmill velocity corresponding to the onset of plasma lactate accumulation (OPLA) were determined for each subject. %ST (R > or equal to .47), VO2max (r > or equal to .83), running economy (r > or equal to .49), VO2 in ml/kg min corresponding to the OPLA (r > or equal to .91) and the treadmill velocity corresponding to OPLA (r > or equal to .91) were significantly (p < .05) related to performance at all distances. Multiple regression analysis showed that the treadmill velocity corresponding to the OPLA was most closely related to performance and the addition of other factors did not significantly raise the multiple R values suggesting that these other variables may interact with the purpose of keeping plasma lactates low during distance races. The slowest and fastest marathoners ran their marathons 7 and 3 m/min faster than their treadmill velocities corresponding to their OPLA which indicates that this relationship is independent of the competitive level of the runner. Runners appear to set a race pace which allows the utilization of the largest possible VO2 which just avoids the exponential rise in plasma lactate.

Mechanical behaviour of the lithosphere beneath the Adamawa uplift (Cameroon, West Africa) based on gravity data

NASA Astrophysics Data System (ADS)

Poudjom Djomani, Y. H.; Diament, M.; Albouy, Y.

1992-07-01

The Adamawa massif in Central Cameroon is one of the African domal uplifts of volcanic origin. It is an elongated feature, 200 km wide. The gravity anomalies over the Adamawa uplift were studied to determine the mechanical behaviour of the lithosphere. Two approaches were used to analyse six gravity profiles that are 600 km long and that run perpendicular to the Adamawa trend. Firstly, the coherence function between topography and gravity was interpreted; secondly, source depth estimations by spectral analysis of the gravity data was performed. To get significant information for the interpretation of the experimental coherence function, the length of the profiles was varied from 320 km to 600 km. This treatment allows one to obtain numerical estimates of the coherence function. The coherence function analysis points out that the lithosphere is deflected and thin beneath the Adamawa uplift, and the Effective Elastic Thickness is of about 20 km. To fit the coherence, a load from below needs to be taken into account. This result on the Adamawa massif is of the same order of magnitude as those obtained on other African uplifts such as Hoggar, Darfur and Kenya domes. For the depth estimation, three major density contrasts were found: the shallowest depth (4-15 km) can be correlated to shear zone structures and the associated sedimentary basins beneath the uplift; the second density contrast (18-38 km) corresponds to the Moho; and finally, the last depth (70-90 km) would be the top of the upper mantle and demotes the low density zone beneath the Adamawa uplift.

Attributing regional effects of the 2014 Jordanian extreme drought to external climate drivers

NASA Astrophysics Data System (ADS)

Bergaoui, Karim; Mitchell, Dann; Zaaboul, Rashyd; Otto, Friederike; McDonnell, Rachael; Dadson, Simon; Allen, Myles

2015-04-01

Throughout 2014, the regions of Jordan, Israel, Lebanon and Syria have experienced a persistent draught with clear impacts on the local populations. In this study we perform an extreme event attribution analysis of how such a draught has changed under climate change, with a specific focus on the flow rate of the Upper Jordan river and the water level of Lake Tiberious (AKA the Sea of Galilee). Both of which hold major societal, political and religious importance. To perform the analysis we make use of distributed computing power to run thousands of modelled years of 2014 with slightly different initial conditions. We use an atmosphere only model (HadAM3p) with a nested 50 km regional model covering Africa and the Middle East. The 50 km model atmospheric variables will be used directly to force offline our 1 km LIS surface model. Two separate experiments and simulations are performed, 1. for all known climate forcings that are present in 2014, and 2. for a naturalised 2014 scenario where we assume humans never impacted the climate. We perform sensitivity analyses on the observed precipitation over the regions of interest, and determine that the TRMM data is in good agreement with station data obtained from the Jordanian Ministry of Water. Using a combination of the TRMM and model data we are able to make clear statements on the attribution of a 2014-like extreme draught event to human causal factors.

Relationship between Aerobic Capacity and Yo-Yo IR1 Performance in Brazilian Professional Futsal Players.

PubMed

Boullosa, Daniel A; Tonello, Lais; Ramos, Isabela; Silva, Alessandro de Oliveira; Simoes, Herbert G; Nakamura, Fabio Y

2013-09-01

To evaluate the relationship between aerobic and intermittent capacities in a team of professional futsal players. FIFTEEN FUTSAL PLAYERS FROM BRAZILIAN FIRST DIVISION (AGE: 25.9±5.1 yrs; height: 1.77±0.04 m, body mass: 74.37±6.02 kg) performed in random order a ramp test and the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) at the start of the season for determination of maximum oxygen consumption (VO2max), peak running speed (Speak), and intermittent running ability. Mean VO2max was of 57.25±6.35 ml·kg(-1)min(-1) with a Speak of 17.69±1.88 km·h(-1). Yo-Yo IR1 performance was of 1,226±282 m. There was no correlation between VO2max and Yo-Yo performance while Speak and Yo-Yo IR1 performance were correlated (r=0.641; P=0.007). From the current results, it may be suggested that both continuous and intermittent physical evaluations are necessary for obtaining a complete fitness profile of futsal players. The low Yo-Yo IR1 performance of Brazilian futsal players when compared to other elite team sport athletes warrants further investigation.

Relationship between Aerobic Capacity and Yo-Yo IR1 Performance in Brazilian Professional Futsal Players

PubMed Central

Boullosa, Daniel A.; Tonello, Lais; Ramos, Isabela; Silva, Alessandro de Oliveira; Simoes, Herbert G.; Nakamura, Fabio Y.

2013-01-01

Purpose To evaluate the relationship between aerobic and intermittent capacities in a team of professional futsal players. Methods Fifteen futsal players from Brazilian first division (age: 25.9±5.1 yrs; height: 1.77±0.04 m, body mass: 74.37±6.02 kg) performed in random order a ramp test and the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) at the start of the season for determination of maximum oxygen consumption (VO2max), peak running speed (Speak), and intermittent running ability. Results Mean VO2max was of 57.25±6.35 ml·kg-1min-1 with a Speak of 17.69±1.88 km·h-1. Yo-Yo IR1 performance was of 1,226±282 m. There was no correlation between VO2max and Yo-Yo performance while Speak and Yo-Yo IR1 performance were correlated (r=0.641; P=0.007). Conclusion From the current results, it may be suggested that both continuous and intermittent physical evaluations are necessary for obtaining a complete fitness profile of futsal players. The low Yo-Yo IR1 performance of Brazilian futsal players when compared to other elite team sport athletes warrants further investigation. PMID:24427483

Preliminary Results of a U.S. Deep South Warm Season Deep Convective Initiation Modeling Experiment using NASA SPoRT Initialization Datasets for Operational National Weather Service Local Model Runs

NASA Technical Reports Server (NTRS)

Medlin, Jeffrey M.; Wood, Lance; Zavodsky, Brad; Case, Jon; Molthan, Andrew

2012-01-01

The initiation of deep convection during the warm season is a forecast challenge in the relative high instability and low wind shear environment of the U.S. Deep South. Despite improved knowledge of the character of well known mesoscale features such as local sea-, bay- and land-breezes, observations show the evolution of these features fall well short in fully describing the location of first initiates. A joint collaborative modeling effort among the NWS offices in Mobile, AL, and Houston, TX, and NASA s Short-term Prediction Research and Transition (SPoRT) Center was undertaken during the 2012 warm season to examine the impact of certain NASA produced products on the Weather Research and Forecasting Environmental Modeling System. The NASA products were: a 4-km Land Information System data, a 1-km sea surface temperature analysis, and a 4-km greenness vegetation fraction analysis. Similar domains were established over the southeast Texas and Alabama coastlines, each with a 9 km outer grid spacing and a 3 km inner nest spacing. The model was run at each NWS office once per day out to 24 hours from 0600 UTC, using the NCEP Global Forecast System for initial and boundary conditions. Control runs without the NASA products were made at the NASA SPoRT Center. The NCAR Model Evaluation Tools verification package was used to evaluate both the forecast timing and location of the first initiates, with a focus on the impacts of the NASA products on the model forecasts. Select case studies will be presented to highlight the influence of the products.

Preliminary Results of a U.S. Deep South Modeling Experiment Using NASA SPoRT Initialization Datasets for Operational National Weather Service Local Model Runs

NASA Technical Reports Server (NTRS)

Wood, Lance; Medlin, Jeffrey M.; Case, Jon

2012-01-01

A joint collaborative modeling effort among the NWS offices in Mobile, AL, and Houston, TX, and NASA Short-term Prediction Research and Transition (SPoRT) Center began during the 2011-2012 cold season, and continued into the 2012 warm season. The focus was on two frequent U.S. Deep South forecast challenges: the initiation of deep convection during the warm season; and heavy precipitation during the cold season. We wanted to examine the impact of certain NASA produced products on the Weather Research and Forecasting Environmental Modeling System in improving the model representation of mesoscale boundaries such as the local sea-, bay- and land-breezes (which often leads to warm season convective initiation); and improving the model representation of slow moving, or quasi-stationary frontal boundaries (which focus cold season storm cell training and heavy precipitation). The NASA products were: the 4-km Land Information System, a 1-km sea surface temperature analysis, and a 4-km greenness vegetation fraction analysis. Similar domains were established over the southeast Texas and Alabama coastlines, each with an outer grid with a 9 km spacing and an inner nest with a 3 km grid spacing. The model was run at each NWS office once per day out to 24 hours from 0600 UTC, using the NCEP Global Forecast System for initial and boundary conditions. Control runs without the NASA products were made at the NASA SPoRT Center. The NCAR Model Evaluation Tools verification package was used to evaluate both the positive and negative impacts of the NASA products on the model forecasts. Select case studies will be presented to highlight the influence of the products.

Small Landslides in Aram-Ares Channel, Mars

NASA Astrophysics Data System (ADS)

Kraal, E. R.; Shoup, J.

2014-12-01

An east-west channel (located at 341°E and 3°N) connects Aram Chaos to Ares Valles. The valley is approximately 80 km long, 12 km wide, and 1.5 km deep. The channel is filled with a series of slope failures or landslides that form lobate aprons covering the valley floor. Preliminary studies of the valley on the north wall of the valley (south facing) characterized 6 landslides using gridded MOLA topography from JMARS, including area, drop height and run out distance. These relatively small landslides have surface areas ranging from 5.6 to 55 km2. Their aprons run out ~ 10 km, often covering the entire width of the valley floor. Drop height was measured using both maximum and minimum estimates due to resolution limits of the topography and ranged from 1200 to 2200 meters. Using the drop height and run out distance, we determine the coefficient of friction and maximum velocity for two of the landslides using previously established landslide equations based on physical properties. The coefficient of friction for the landslide events ranged from 0.5 to 1.5, which corresponds to a maximum landslide velocity of 87 m/s2 to 96 m/s2. The variations in the coefficients may be due to landslides size, relative size, or possible volatile or ice content. Preliminary geomorphic surface mapping is currently under way to identify the relationship between the aprons and the channel floor, relative age of the landslides, and other characteristics. Initial analysis indicates the channel floor and depositional aprons have experienced deflation and eolian processes and aprons have a variable level of erosion indicating that the landslides did not form during a single event.

Validating GPM-based Multi-satellite IMERG Products Over South Korea

NASA Astrophysics Data System (ADS)

Wang, J.; Petersen, W. A.; Wolff, D. B.; Ryu, G. H.

2017-12-01

Accurate precipitation estimates derived from space-borne satellite measurements are critical for a wide variety of applications such as water budget studies, and prevention or mitigation of natural hazards caused by extreme precipitation events. This study validates the near-real-time Early Run, Late Run and the research-quality Final Run Integrated Multi-Satellite Retrievals for GPM (IMERG) using Korean Quantitative Precipitation Estimation (QPE). The Korean QPE data are at a 1-hour temporal resolution and 1-km by 1-km spatial resolution, and were developed by Korea Meteorological Administration (KMA) from a Real-time ADjusted Radar-AWS (Automatic Weather Station) Rainrate (RAD-RAR) system utilizing eleven radars over the Republic of Korea. The validation is conducted by comparing Version-04A IMERG (Early, Late and Final Runs) with Korean QPE over the area (124.5E-130.5E, 32.5N-39N) at various spatial and temporal scales during March 2014 through November 2016. The comparisons demonstrate the reasonably good ability of Version-04A IMERG products in estimating precipitation over South Korea's complex topography that consists mainly of hills and mountains, as well as large coastal plains. Based on this data, the Early Run, Late Run and Final Run IMERG precipitation estimates higher than 0.1mm h-1 are about 20.1%, 7.5% and 6.1% higher than Korean QPE at 0.1o and 1-hour resolutions. Detailed comparison results are available at https://wallops-prf.gsfc.nasa.gov/KoreanQPE.V04/index.html

High-intensity sprint fatigue does not alter constant-submaximal velocity running mechanics and spring-mass behavior.

PubMed

Morin, Jean-Benoit; Tomazin, Katja; Samozino, Pierre; Edouard, Pascal; Millet, Guillaume Y

2012-04-01

We investigated the changes in constant velocity spring-mass behavior after high intensity sprint fatigue in order to better interpret the results recently reported after ultra-long distance (ULD) exercises. Our hypothesis was that after repeated sprints (RS), subjects may likely experience losses of force such as after ULD, but the necessity to modify their running pattern to attenuate the overall impact at each step (such as after ULD) may not be present. Eleven male subjects performed four sets of five 6-s sprints with 24-s recovery between sprints and 3 min between sets, on a sprint treadmill and on a bicycle ergometer. For each session, their running mechanics and spring-mass characteristics were measured at 10 and 20 km h(-1) on an instrumented treadmill before and after RS. Two-way (period and velocity) ANOVAs showed that high-intensity fatigue did not induce any change in the constant velocity running pattern at low or high velocity, after both running and cycling RS, despite significant decreases (P < 0.001) in maximal power (-27.1 ± 8.2% after running RS and -15.4 ± 11.5 % after cycling RS) and knee extensors maximal voluntary force (-18.8 ± 6.7 % after running RS and -15.0 ± 7.6 % after cycling RS). These results bring indirect support to the hypothesis put forward in recent ULD studies that the changes in running mechanics observed after ULD are likely not related to the decrease in strength capabilities, but rather to the necessity for subjects to adopt a protective running pattern.

Global 7 km mesh nonhydrostatic Model Intercomparison Project for improving TYphoon forecast (TYMIP-G7): experimental design and preliminary results

NASA Astrophysics Data System (ADS)

Nakano, Masuo; Wada, Akiyoshi; Sawada, Masahiro; Yoshimura, Hiromasa; Onishi, Ryo; Kawahara, Shintaro; Sasaki, Wataru; Nasuno, Tomoe; Yamaguchi, Munehiko; Iriguchi, Takeshi; Sugi, Masato; Takeuchi, Yoshiaki

2017-03-01

Recent advances in high-performance computers facilitate operational numerical weather prediction by global hydrostatic atmospheric models with horizontal resolutions of ˜ 10 km. Given further advances in such computers and the fact that the hydrostatic balance approximation becomes invalid for spatial scales < 10 km, the development of global nonhydrostatic models with high accuracy is urgently required. The Global 7 km mesh nonhydrostatic Model Intercomparison Project for improving TYphoon forecast (TYMIP-G7) is designed to understand and statistically quantify the advantages of high-resolution nonhydrostatic global atmospheric models to improve tropical cyclone (TC) prediction. A total of 137 sets of 5-day simulations using three next-generation nonhydrostatic global models with horizontal resolutions of 7 km and a conventional hydrostatic global model with a horizontal resolution of 20 km were run on the Earth Simulator. The three 7 km mesh nonhydrostatic models are the nonhydrostatic global spectral atmospheric Double Fourier Series Model (DFSM), the Multi-Scale Simulator for the Geoenvironment (MSSG) and the Nonhydrostatic ICosahedral Atmospheric Model (NICAM). The 20 km mesh hydrostatic model is the operational Global Spectral Model (GSM) of the Japan Meteorological Agency. Compared with the 20 km mesh GSM, the 7 km mesh models reduce systematic errors in the TC track, intensity and wind radii predictions. The benefits of the multi-model ensemble method were confirmed for the 7 km mesh nonhydrostatic global models. While the three 7 km mesh models reproduce the typical axisymmetric mean inner-core structure, including the primary and secondary circulations, the simulated TC structures and their intensities in each case are very different for each model. In addition, the simulated track is not consistently better than that of the 20 km mesh GSM. These results suggest that the development of more sophisticated initialization techniques and model physics is needed to further improve the TC prediction.

Mechanisms for improved running economy in beginner runners.

PubMed

Moore, Isabel S; Jones, Andrew M; Dixon, Sharon J

2012-09-01

Controversy surrounds whether running mechanics make good predictors of running economy (RE) with little known about the development of an economical running gait. The aim of this study was to identify if mechanical or physiological variables changed during 10 wk of running in beginners and whether these changes could account for any change in RE. A 10-wk running program (10 wkRP) was completed by 10 female beginner runners. A bilateral three-dimensional kinematic and kinetic analysis, in addition to RE and lower body flexibility measurements, was performed before and after the 10 wkRP. The Balke-Ware graded walking exercise test was performed before and after the 10 wkRP to determine VO2max. Seven kinematic and kinetic variables significantly changed from before to after training, in addition to a significant decrease in calf flexibility (27.3° ± 6.3° vs 23.9° ± 5.6°, P < 0.05). A significant improvement was seen in RE (224 ± 24 vs 205 ± 27 mL · kg(-1) · km(-1), P < 0.05) and treadmill time to exhaustion (16.4 ± 3.2 vs 17.3 ± 2.8 min, P < 0.05); however, VO2max remained unchanged from before to after training (34.7 ± 5.1 vs 34.3 ± 5.6 mL · kg(-1) · min(-1)). Stepwise regression analysis showed three kinematic variables to explain 94.3% of the variance in change in RE. They were a less extended knee at toe off (P = 0.004), peak dorsiflexion occurring later in stance (P = 0.001), and a slower eversion velocity at touchdown (P = 0.042). The magnitude of change for each variable was 1.5%, 4.7%, and 34.1%, respectively. These results show that beginner runners naturally developed their running gait as they became more economical runners.

Caffeine-containing energy drink improves physical performance of elite rugby players during a simulated match.

PubMed

Del Coso, Juan; Ramírez, Juan A; Muñoz, Gloria; Portillo, Javier; Gonzalez-Millán, Cristina; Muñoz, Víctor; Barbero-Álvarez, José C; Muñoz-Guerra, Jesús

2013-04-01

The purpose of this study was to investigate the effectiveness of a caffeine-containing energy drink in enhancing rugby players' physical performance during a simulated match. A second purpose was to determine the urinary caffeine excretion derived from the energy drink intake. In a randomized and counterbalanced order, 26 elite rugby players (mean ± SD for age and body mass, 25 ± 2 y and 93 ± 15 kg) played 2 simulated rugby games (2 × 30 min) 60 min after ingesting (i) 3 mg of caffeine per kilogram of body mass in the form of an energy drink (Fure, ProEnergetics) or (ii) the same drink without caffeine (placebo). During the matches, the individual running distance and the instantaneous speed were measured, and the number of running actions above 20 km·h(-1) (i.e., sprints) were determined, using global positioning system devices. The number of impacts above 5 g during the matches was determined by accelerometry. The ingestion of the energy drink, compared with the placebo, increased the total distance covered during the match (4749 ± 589 vs 5139 ± 475 m, p < 0.05), the running distance covered at more than 20 km·h(-1) (184 ± 38 vs 208 ± 38 m, p < 0.05), and the number of sprints (10 ± 7 vs 12 ± 7, p < 0.05). The ingestion of the energy drink also resulted in a greater overall number of impacts (481 ± 352 vs 641 ± 366, p < 0.05) and a higher postexercise urine caffeine concentration (0.1 ± 0.1 vs 2.4 ± 0.9 μg·mL(-1), p < 0.05). The use of an energy drink with a caffeine dose equivalent to 3 mg·kg(-1) considerably enhanced the movement patterns of rugby players during a simulated match.

The mechanics of sprint running

PubMed Central

Cavagna, Giovanni A.; Komarek, L.; Mazzoleni, Stefania

1971-01-01

1. The effect of the velocity of shortening on the power developed by the muscles in sprint running was studied by measuring the mechanical work done to accelerate the body forward from the start to about 34 km/hr. 2. The work was measured at each step from the data obtained by means of a platform sensitive to the force impressed by the foot. 3. Almost the totality of the positive work done during the first second from the start is found as an increase of the kinetic energy of the body. However, as the speed of the run rises, air resistance and particularly the deceleration of the body forward, taking place at each step, rapidly increase, limiting the speed of the run. 4. The average power developed by the muscles during the push at each step increases with the velocity of running reaching 3-4 h.p. at the maximal speed attained. 5. At low speed the contractile component of the muscles seems to be mainly responsible for the power output, whereas at high speed (25-34 km/hr) an appreciable fraction of the power appears to be sustained by the mechanical energy stored in the `series elastic elements' during stretching the contracted muscles (negative work) and released immediately after in the positive work phase. ImagesFig. 1 PMID:5098087

Effect of sodium bicarbonate on prolonged running performance: A randomized, double-blind, cross-over study.

PubMed

Freis, Tanja; Hecksteden, Anne; Such, Ulf; Meyer, Tim

2017-01-01

The ability to sustain intense exercise seems to be partially limited by the body's capability to counteract decreases in both intra- and extracellular pH. While the influence of an enhanced buffering capacity via sodium bicarbonate (BICA) on short-term, high-intensity exercise performance has been repeatedly investigated, studies on prolonged endurance performances are comparatively rare, especially for running. The aim of the following study was to assess the ergogenic effects of an oral BICA substitution upon exhaustive intensive endurance running performance. In a double-blind randomized cross-over study, 18 trained runners (VO2peak: 61.2 ± 6.4 ml•min-1•kg-1) performed two exhaustive graded exercise tests and two constant load tests (30 main at 95% individual anaerobic threshold (IAT) followed by 110% IAT until exhaustion) after ingestion of either sodium bicarbonate (BICA) (0.3 g/kg) or placebo (4 g NaCl) diluted in 700 ml of water. Time to exhaustion (TTE) in the constant load test was defined as the main outcome measure. Throughout each test respiratory gas exchange measurements were conducted as well as determinations of heart rate, blood gases and blood lactate concentration. TTE in the constant load test did not differ significantly between BICA and placebo conditions (BICA: 39.6 ± 5.6 min, placebo: 39.3 ± 5.6 min; p = 0.78). While pH in the placebo test dropped to a slightly acidotic value two minutes after cessation of exercise (7.34 ± 0.05) the value in the BICA trial remained within the normal range (7.41 ± 0.06) (p < 0.001). In contrast, maximum running speed (Vmax) in the exhaustive graded exercise test was significantly higher with BICA (17.4 ± 1.0 km/h) compared to placebo (17.1 ± 1.0 km/h) (p = 0.009). The numerical difference in maximum oxygen consumption (VO2peak) failed to reach statistical significance (BICA: 61.2 ± 6.4 ml•min-1•kg-1, placebo: 59.8 ± 6.4 ml•min-1•kg-1; p = 0.31). Maximum blood lactate was significantly higher with BICA compared to the corresponding placebo test (BICA: 11.1 ± 2.3 mmol/l, placebo: 8.9 ± 3.0 mmol/l; p < 0.001). At the end of exercise, an acidotic pH value was found in both exhaustive graded exercise tests (p = 0.002). BICA caused gastrointestinal side effects in 15 patients. Maximal performance was enhanced significantly after BICA administration. The ergogenic effect of BICA in the exhaustive graded exercise test can most likely be attributed to an increased anaerobic glycolysis that is reflected by an accumulation of lactate. However, TTE in prolonged high-intensity running was not improved. Even at the end of exercise no severe metabolic acidosis was found. Metabolic acidification as one of the dominant factors causing muscular fatigue should therefore be reconsidered. German Clinical Trials Register (DRKS) DRKS00011284.

[Analysis of surface composition of three-way catalysts of in-use vehicles].

PubMed

Xie, Shu-xia; Hu, Jing-nan; Bao, Xiao-feng; Zhang, Ke-song; Li, Zhen-hua; Wang, Hai-tao

2010-07-01

The kinds and contents of surface elements in three-way catalysts of six light-duty in-use taxi cabs, which were mainly operated in Beijing and whose driving mileages were in the range of 34 x 10(4)-59 x 10(4) km, were determined by X-ray fluorescence spectrometry (XRF), and the effect of driving mileage on element content was investigated. Results showed that nearly 30 kinds of elements were present on the catalyst surface. The main elements of different samples were similar. The common elements of the pollutant on the front and rear catalysts were P, Ca, Zn and Mn etc., most of which are from engine oil and gasoline. S was only observed on the rear catalysts, indicating that S tends to deposit on the rear catalysts. After 34 x 10(4) km run, the P content increased very slowly and 40 x 10(4) km run S content reached a saturated value. While the contents of Ca, Zn and Mn still exhibit an increase tendency after 56 x 10(4) km. That means after 40 x 10(4) km driving mileage, the effects of P and S on the catalyst activity are minor, and the continuous deposit of Ca, Zn and Mn will lead to further decrease of the activity.

European extra-tropical storm damage risk from a multi-model ensemble of dynamically-downscaled global climate models

NASA Astrophysics Data System (ADS)

Haylock, M. R.

2011-10-01

Uncertainty in the return levels of insured loss from European wind storms was quantified using storms derived from twenty-two 25 km regional climate model runs driven by either the ERA40 reanalyses or one of four coupled atmosphere-ocean global climate models. Storms were identified using a model-dependent storm severity index based on daily maximum 10 m wind speed. The wind speed from each model was calibrated to a set of 7 km historical storm wind fields using the 70 storms with the highest severity index in the period 1961-2000, employing a two stage calibration methodology. First, the 25 km daily maximum wind speed was downscaled to the 7 km historical model grid using the 7 km surface roughness length and orography, also adopting an empirical gust parameterisation. Secondly, downscaled wind gusts were statistically scaled to the historical storms to match the geographically-dependent cumulative distribution function of wind gust speed. The calibrated wind fields were run through an operational catastrophe reinsurance risk model to determine the return level of loss to a European population density-derived property portfolio. The risk model produced a 50-yr return level of loss of between 0.025% and 0.056% of the total insured value of the portfolio.

A meteorological distribution system for high-resolution terrestrial modeling (MicroMet)

Treesearch

Glen E. Liston; Kelly Elder

2006-01-01

An intermediate-complexity, quasi-physically based, meteorological model (MicroMet) has been developed to produce high-resolution (e.g., 30-m to 1-km horizontal grid increment) atmospheric forcings required to run spatially distributed terrestrial models over a wide variety of landscapes. The following eight variables, required to run most terrestrial models, are...

Dynamic Parameters Variability: Time Interval Interference on Ground Reaction Force During Running.

PubMed

Pennone, Juliana; Mezêncio, Bruno; Amadio, Alberto C; Serrão, Júlio C

2016-04-01

The aim of this study was to determine the effect of the time between measures on ground reaction force running variability; 15 healthy men (age = 23.8 ± 3.7 years; weight = 72.8 ± 7.7 kg; height 174.3 ± 8.4 cm) performed two trials of running 45 minutes at 9 km/hr at intervals of seven days. The ground reaction forces were recorded every 5 minutes. The coefficients of variation of indicative parameters of the ground reaction forces for each condition were compared. The coefficients of variations of the ground reaction forces curve analyzed between intervals and sessions were 21.9% and 21.48%, respectively. There was no significant difference for the ground reaction forces parameters Fy1, tFy1, TC1, Imp50, Fy2, and tFy2 between intervals and sessions. Although the ground reaction forces variables present a natural variability, this variability in intervals and in sessions remained consistent, ensuring a high reliability in repeated measures designs. © The Author(s) 2016.

Correlation between river slope and meandering variability (obtained by DGPS data) and morphotectonics for two Andean tributaries of the Amazon river: the case of Beni (Bolivia) and Napo (Ecuador-Peru) rivers.

NASA Astrophysics Data System (ADS)

Bourrel, L.; Darrozes, J.; Guyot, J.; Christophoul, F.; Bondoux, F.

2007-05-01

The Beni river drains a catchment area of 282 000 km2 of which 40 percent are located in the Cordillera of the Bolivian and Peruvian Andes, and the rest in the Amazonian plain : the studied reaches runs from Guanay (Andean Piedmont) to Riberalta (junction with Madre de Dios river) that represents a distance by the river of 1055 km. The Napo river starts in the Ecuadorian Andes and leaves Ecuador in Nuevo Rocafuerte (27 400 km2) and enters in Peru until its junction with the Amazon river : the studied section runs from Misahualli (Andean Piedmont) to this junction, that represents a distance by the river of 995 km. The GPS data were acquired using a mobile GPS embarked on a boat and 4 fixed bases located along the Beni river, 6 along the Napo river and the two rivers profile calculated from post-treated differential GPS solutions. For the Beni river, two sectors were identified: - the upstream sector (~230 km) between Guanay (414 m) and 50 km downstream Rurrenabaque (245 m) is located in Andean Piedmont, which consists in a series of thrusts associated with anticlines and synclines (the subandean zone), and presents slope values range between 135 cm/km and 10 cm/km and an average index of sinuosity (IS) of 1.29, - the downstream sector (~ 820 km) which runs in Amazonian plain (until Riberalta -165 m-), is characterized by an average slope of 8 cm/km and an average IS of 2.06 (this sector is much more homogeneous and the Beni river shows a meandering channel). For the Napo River, three sectors were identified: - the first sector (~140 km) between Misahualli (401 m) and Coca (265 m), is located in Andean Piedmont (subandean zone) and presents slope values range between 170 cm/km and 30 cm/km and an average IS of 1.6, - the second sector (~250 km) between Coca (when the Napo river enters in the Amazonian plain) and Nuevo Rocafuerte (190 m), presents slope values range between 30 cm/km and 20 cm/km and an average IS of 1.2, and a convex-up shape profile corresponding to the preserved part of the Pastaza-Napo Megafan, not yet affected by headwater erosion, - the third sector (~600 km) between Nuevo Rocafuerte and the confluence with the Amazon river (101 m), where the Napo river flows through the quaternary deposits of the Pastaza-Napo Megafan, presents slope values ranging from 20 to 10 cm/km and an average IS of 1.2, and is characterized by a more classical concave-up shape profile. Our main results established using DGPS data (an important difference between the slope and IS averages of the Napo and the Beni rivers in their Amazonian part, respectively ~20 cm/km and ~8 cm/km, ie a ratio ~2.5, 1.2 and 2.06, ie a ratio ~0.6) bring an additional explanation to the results obtained by the preceding authors, with balance methods, and confirm respectively the erosion and the sedimentation behaviour of the Napo and the Beni rivers.

Atmospheric blocking in the Climate SPHINX simulations: the role of orography and resolution

NASA Astrophysics Data System (ADS)

Davini, Paolo; Corti, Susanna; D'Andrea, Fabio; Riviere, Gwendal; von Hardenberg, Jost

2017-04-01

The representation of atmospheric blocking in numerical simulations, especially over the Euro-Atlantic region, still represents a main concern for the climate modelling community. We here discuss the Northern Hemisphere winter atmospheric blocking representation in a set of 30-year simulations which has been performed in the framework of the PRACE project "Climate SPHINX". Simulations were run using the EC-Earth Global Climate Model with several ensemble members at 5 different horizontal resolutions (ranging from 125 km to 16 km). Results show that the negative bias in blocking frequency over Europe becomes negligible at resolutions of about 40 km and finer. However, the blocking duration is still underestimated by 1-2 days, suggesting that the correct blocking frequencies are achieved with an overestimation of the number of blocking onsets. The reasons leading to such improvements are then discussed, highlighting the role of orography in shaping the Atlantic jet stream: at higher resolution the jet is weaker and less penetrating over Europe, favoring the breaking of synoptic Rossby waves over the Atlantic stationary ridge and thus increasing the simulated blocking frequency.

Joint Evaluation of Copernicus Atmosphere Monitoring Service (CAMS) High-resolution Global Near-Real Time CO and CO2 Forecasts during KORUS-AQ Field Campaign

NASA Astrophysics Data System (ADS)

Tang, W.; Arellano, A. F., Jr.; Choi, Y.; DiGangi, J. P.; Woo, J. H.; Diskin, G. S.; Agusti-panareda, A.; Parrington, M.; Massart, S.; Lee, M.; Kanaya, Y.; Jang, J.; Lee, Y.; Hong, J.; Flynn, J. H., III; Thompson, A. M.; Kim, D. B.

2017-12-01

Anthropogenic combustion has significant impacts on air quality and climate. To understand anthropogenic combustion, it is critical to model CO2 and CO (key combustion signatures) and their relationships. In this study, we jointly evaluate the Copernicus Atmosphere Monitoring Service (CAMS) free-running 16-km forecast, 9-km forecast initialized with CAMS analysis, and analysis products of CO (80km) and CO2 (40km) to understand how well combustion-related processes and constituent transport are represented in the current system. We use measurements from aircraft, ground sites, and ships during the KORUS-AQ field campaign (May - June 2016), along with satellite observations (MOPITT, IASI, OCO-2, and GOSAT). Airborne measurements by the DC-8 aircraft are classified into five regions: Seoul metropolitan, Taehwa, West Sea, Seoul-Jeju jetway, and Seoul-Busan jetway. The observed CO2, CO, and their relationships varies significantly, and the performance of CAMS products also varies across regions. The three CAMS products perform reasonably well in simulating anthropogenic combustion processes. Overall, CO2 is overestimated while CO is underestimated by CAMS. The 9km forecast product generally has a better performance than the other two, because of its higher model resolution and better initialization conditions. The analysis product also performs better than the 16km forecast. China outflow over West Sea is captured, but CO2 and CO is underestimated in the outflow. According to CAMS, is 10-15 (ppbv/ppmv) for Korea and about 30 for China outflow, indicating anthropogenic combustion in Seoul is more efficient than it is in China. This agrees well with DC-8 aircraft observations. As for ground sites, we find that CO and CO2 measured by the Olympic park and Yonsei (Seoul metropolitan sites) have more regularity in diurnal cycle, and such periodical change is well captured by CAMS. The time series for CO from Baengnyeong, and Fukue (remote sites) are irregular and episodic, which are more related to transport rather than local emissions. CAMS performances over Taehwa site are impacted by both local processes and transport. These comparisons indicate vertical mixing near sources may be an issue for CAMS. Compared to satellite observations, CO analyses show a better agreement, while for CO2, the forecasts are better.

Velocity distribution of women's 30-km cross-country skiing during Olympic Games from 2002-2014.

PubMed

Erdmann, Wlodzimierz S; Dancewicz-Nosko, Dorota; Giovanis, Vasilios

2017-12-01

Within several investigated endurance sport disciplines the distribution of load of the best competitors has a manner of evenly or slightly rising velocity values. Unfortunately many other competitors have usually diminishing values or when they are very poor they have evenly values. The aim of this study was to investigate distribution of velocity within 30-km cross-country female skiers. Cross-country skiing runs were investigated of Olympic Games 2002-2014 (Salt Lake City, Turin, Vancouver, Sochi). At every race two 15 km or three 10 km loops of the same vertical profile were taken into account. The competitors were divided onto: A - winners, B - medallists, C - competitors who obtained places 4 to 10 at the finish line (medium runners), D - competitors who obtained places 11 to 30 at the finish line (poor runners). Velocity data presented on the web pages of several institutions were utilized. The competitors had their velocity distributed in a manner with usually diminishing values. While comparing velocity of sequential loops with the mean velocity the difference for the poor runners reached the value of almost 6 %, which was too high. There was significant (usually negative) correlation coefficient between values of velocity deviation for the first and second loops and the mean value of velocity for the entire distance for the better runners and mixed, i.e. positive and negative values for the poorer runners. It was postulated investigations of velocity distribution should be introduced in coaching in order to inform competitors about their running. This advise is especially important for the poorer runners. Up to now cross country skiers run for themselves. It should be discussed whether the tactics used by road and track runners, i.e. running with pace makers, can be introduced in cross country skiing. Also the use of a drone during training can be used in order to maintain proper pace.

Energy cost of wheel running in house mice: implications for coadaptation of locomotion and energy budgets.

PubMed

Koteja, P; Swallow, J G; Carter, P A; Garland, T

1999-01-01

Laboratory house mice (Mus domesticus) that had experienced 10 generations of artificial selection for high levels of voluntary wheel running ran about 70% more total revolutions per day than did mice from random-bred control lines. The difference resulted primarily from increased average velocities rather than from increased time spent running. Within all eight lines (four selected, four control), females ran more than males. Average daily running distances ranged from 4.4 km in control males to 11.6 km in selected females. Whole-animal food consumption was statistically indistinguishable in the selected and control lines. However, mice from selected lines averaged approximately 10% smaller in body mass, and mass-adjusted food consumption was 4% higher in selected lines than in controls. The incremental cost of locomotion (grams food/revolution), computed as the partial regression slope of food consumption on revolutions run per day, did not differ between selected and control mice. On a 24-h basis, the total incremental cost of running (covering a distance) amounted to only 4.4% of food consumption in the control lines and 7.5% in the selected ones. However, the daily incremental cost of time active is higher (15.4% and 13.1% of total food consumption in selected and control lines, respectively). If wheel running in the selected lines continues to increase mainly by increases in velocity, then constraints related to energy acquisition are unlikely to be an important factor limiting further selective gain. More generally, our results suggest that, in small mammals, a substantial evolutionary increase in daily movement distances can be achieved by increasing running speed, without remarkable increases in total energy expenditure.

[Assessment of cardiorespiratory fitness in preschool children: adaptation of the 20 metres shuttle run test].

PubMed

Cadenas-Sánchez, Cristina; Alcántara-Moral, Francisco; Sánchez-Delgado, Guillermo; Mora-González, José; Martínez-Téllez, Borja; Herrador-Colmenero, Manuel; Jiménez-Pavón, David; Femia, Pedro; Ruiz, Jonatan R; Ortega, Francisco B

2014-12-01

Cardiorespiratory fitness is a strong indicator of present and future health in children and adolescents, however it is unknown whether it is for pre-schoolers, from 3 to 5 years. In the present study, we described the adaptation of the original 20m shuttle run test, it feasibility and acceptance in children from 3 to 5 years and its maximality and reliability. A total of 130 students (4.91 ± 0.89 years; 77 boys) performed the test twice, two weeks apart. The test adaptation consisted mainly in reducing the initial speed of 8.5 km/h to 6.5 km/h. The test was feasible and was well accepted in both boys and girls and the three age groups, 3, 4 and 5 years. The maximum heart rate (MHR) achieved for the entire sample was 199.4 ± 12.5 beats/min, equivalent to 97% of the estimated theoretical MHR, and no significant differences by gender or age. Mean test-retest difference (systematic error) in the number of laps achieved was 2 laps, with no significant differences between sex or age. There was no evidence of heteroscedasticity. Our results suggest the test is maximum and reliable in this age group. Future longitudinal or intervention studies using this test should take into account that changes in the test performance of 2 laps may be due to the variability of the measure, while wider changes would be attributable to the intervention or changes associated with age. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Automated object-based classification of rain-induced landslides with VHR multispectral images in Madeira Island

NASA Astrophysics Data System (ADS)

Heleno, S.; Matias, M.; Pina, P.; Sousa, A. J.

2015-09-01

A method for semi-automatic landslide detection, with the ability to separate source and run-out areas, is presented in this paper. It combines object-based image analysis and a Support Vector Machine classifier on a GeoEye-1 multispectral image, sensed 3 days after the major damaging landslide event that occurred in Madeira island (20 February 2010), with a pre-event LIDAR Digital Elevation Model. The testing is developed in a 15 km2-wide study area, where 95 % of the landslides scars are detected by this supervised approach. The classifier presents a good performance in the delineation of the overall landslide area. In addition, fair results are achieved in the separation of the source from the run-out landslide areas, although in less illuminated slopes this discrimination is less effective than in sunnier east facing-slopes.

The Activity Profile of Young Tennis Athletes Playing on Clay and Hard Courts: Preliminary Data.

PubMed

Adriano Pereira, Lucas; Freitas, Victor; Arruda Moura, Felipe; Saldanha Aoki, Marcelo; Loturco, Irineu; Yuzo Nakamura, Fábio

2016-04-01

The aim of this study was to compare the kinematic characteristics of tennis matches between red clay and hard courts in young tennis players. Eight young tennis players performed two tennis matches on different court surfaces. The match activities were monitored using GPS units. The distance covered in different velocity ranges and the number of accelerations were analyzed. The paired t test and inference based on magnitudes were used to compare the match physical performance between groups. The total distance (24% of difference), high-intensity running distance (15 - 18 km/h) (30% of difference), the number of high-intensity activities (44% of difference), the body load (1% of difference), and accelerations >1.5 g (1.5-2 g and >2 g 7.8 and 8.1 % of difference, respectively) were significantly greater in clay court than hard court matches ( p < 0.05). Matches played on the red clay court required players to cover more total and high-intensity running distances and engage in more high-intensity activities than the matches played on the hard court. Finally, on the clay court the body load and the number of accelerations performed (>1.5 g) were possibly higher than on the hard court.

Voluntary Running Exercise-Mediated Enhanced Neurogenesis Does Not Obliterate Retrograde Spatial Memory.

PubMed

Kodali, Maheedhar; Megahed, Tarick; Mishra, Vikas; Shuai, Bing; Hattiangady, Bharathi; Shetty, Ashok K

2016-08-03

Running exercise (RE) improves cognition, formation of anterograde memories, and mood, alongside enhancing hippocampal neurogenesis. A previous investigation in a mouse model showed that RE-induced increased neurogenesis erases retrograde memory (Akers et al., 2014). However, it is unknown whether RE-induced forgetting is common to all species. We ascertained whether voluntary RE-induced enhanced neurogenesis interferes with the recall of spatial memory in rats. Young rats assigned to either sedentary (SED) or running exercise (RE) groups were first subjected to eight learning sessions in a water maze. A probe test (PT) conducted 24 h after the final training session confirmed that animals in either group had a similar ability for the recall of short-term memory. Following this, rats in the RE group were housed in larger cages fitted with running wheels, whereas rats in the SED group remained in standard cages. Animals in the RE group ran an average of 78 km in 4 weeks. A second PT performed 4 weeks after the first PT revealed comparable ability for memory recall between animals in the RE and SED groups, which was evidenced through multiple measures of memory retrieval function. The RE group displayed a 1.5- to 2.1-fold higher hippocampal neurogenesis than SED rats. Additionally, both moderate and brisk RE did not interfere with the recall of memory, although increasing amounts of RE proportionally enhanced neurogenesis. In conclusion, RE does not impair memory recall ability in a rat model despite substantially increasing neurogenesis. Running exercise (RE) improves new memory formation along with an increased neurogenesis in the hippocampus. In view of a recent study showing that RE-mediated increased hippocampal neurogenesis promotes forgetfulness in a mouse model, we ascertained whether a similar adverse phenomenon exists in a rat model. Memory recall ability examined 4 weeks after learning confirmed that animals that had run a mean of 78 km and displayed a 1.5- to 2.1-fold increase in hippocampal neurogenesis demonstrated similar proficiency for memory recall as animals that had remained sedentary. Furthermore, both moderate and brisk RE did not interfere with memory recall, although increasing amounts of RE proportionally enhanced neurogenesis, implying that RE has no adverse effects on memory recall. Copyright © 2016 the authors 0270-6474/16/368112-11$15.00/0.

Why even active people get fatter--the asymmetric effects ofincreasing and decreasing exercise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Paul T.

2006-01-06

Background: Public health policies for preventing obesityneed guidelines for active individuals who are at risk due to exerciserecidivism. Methods: Changes in adiposity were compared to the runningdistances at baseline and follow-up in men and women whose reportedexercise increased (N=4,632 and 1,953, respectively) or decreased (17,280and 5,970, respectively) during 7.7 years of follow-up. Results: PerDelta km/wk, decreases in running distance caused over four-fold greaterweight gain between 0-8 km/wk (slope+-SE, males: -0.068+ -0.005 kg/m2,females: -0.080+-0.01 kg/m2) than between 32-48 km/wk (-0.017+-0.002 and-0.010+-0.005 kg/m2, respectively). In contrast, increases in runningdistance produced the smallest weight losses between 0-8 km/wk andstatistically significant weight loss onlymore » above 16 km/wk in males and 32km/wk in females. Above 32 km/wk (30 kcal/kg) in men and 16 km/wk (15kcal/kg) in women, weight loss from increasing exercise was equal to orgreater than weight gained with decreasing exercise, otherwise weightgain exceeded weight loss. Substantial weight gain occurred in runnerswho quit running, which would be mostly retained with resumed activity.Conclusion: Public health recommendations should warn against the risksof irreversible weight gain with exercise cessation. Weight gained due toreductions in exercise below 30 kcal/kg in men and 15 kcal/kg in womenmay not be reversed by resuming prior activity. Current IOM guidelines(i.e., maintain total energy expenditure at 160 percent of basal) agreewith the men s exercise threshold for symmetric weight change withchanging exercise levels.« less

Evaluating the impact of chemical boundary conditions on near surface ozone in regional climate-air quality simulations over Europe

NASA Astrophysics Data System (ADS)

Akritidis, D.; Zanis, P.; Katragkou, E.; Schultz, M. G.; Tegoulias, I.; Poupkou, A.; Markakis, K.; Pytharoulis, I.; Karacostas, Th.

2013-12-01

A modeling system based on the air quality model CAMx driven off-line by the regional climate model RegCM3 is used for assessing the impact of chemical lateral boundary conditions (LBCs) on near surface ozone over Europe for the period 1996-2000. The RegCM3 and CAMx simulations were performed on a 50 km × 50 km grid over Europe with RegCM3 driven by the NCEP meteorological reanalysis fields and CAMx with chemical LBCs from ECHAM5/MOZART global model. The recent past period (1996-2000) was simulated in three experiments. The first simulation was forced using time and space invariant LBCs, the second was based on ECHAM5/MOZART chemical LBCs fixed for the year 1996 and the third was based on ECHAM5/MOZART chemical LBCs with interannual variability. Anthropogenic and biogenic emissions were kept identical for the three sensitivity runs.

International variability in 20 m shuttle run performance in children and youth: who are the fittest from a 50-country comparison? A systematic literature review with pooling of aggregate results.

PubMed

Lang, Justin J; Tremblay, Mark S; Léger, Luc; Olds, Tim; Tomkinson, Grant R

2018-02-01

To describe and compare 20 m shuttle run test (20mSRT) performance among children and youth across 50 countries; to explore broad socioeconomic indicators that correlate with 20mSRT performance in children and youth across countries and to evaluate the utility of the 20mSRT as an international population health indicator for children and youth. A systematic review was undertaken to identify papers that explicitly reported descriptive 20mSRT (with 1-min stages) data on apparently healthy 9-17 year-olds. Descriptive data were standardised to running speed (km/h) at the last completed stage. Country-specific 20mSRT performance indices were calculated as population-weighted mean z-scores relative to all children of the same age and sex from all countries. Countries were categorised into developed and developing groups based on the Human Development Index, and a correlational analysis was performed to describe the association between country-specific performance indices and broad socioeconomic indicators using Spearman's rank correlation coefficient. Performance indices were calculated for 50 countries using collated data on 1 142 026 children and youth aged 9-17 years. The best performing countries were from Africa and Central-Northern Europe. Countries from South America were consistently among the worst performing countries. Country-specific income inequality (Gini index) was a strong negative correlate of the performance index across all 50 countries. The pattern of variability in the performance index broadly supports the theory of a physical activity transition and income inequality as the strongest structural determinant of health in children and youth. This simple and cost-effective assessment would be a powerful tool for international population health surveillance. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

PERFORMANCE AND DURABILITY OF THE PSA PEUGEOT CITROEN'S DPF SYSTEM ON A TAXI FLEET IN THE PARIS AREA

DOE Office of Scientific and Technical Information (OSTI.GOV)

COROLLER, P; PLASSAT, G

The use of Diesel engines has strongly increased during the last years and now represents 40% of the sales in Europe and up to 50% of the number of cars in circulation for some countries. This success is linked not only to the economical aspect of the use of such vehicles, but also to the recent technological improvements of these engines. The new technical solutions (high pressure direct injection, turbocharger) have indeed allowed the increase of these engine performances while decreasing their fuel consumption, pollutant emissions and noise level. From an environment point of view, Diesel engines are nevertheless penalizedmore » by their particulates and NOx emissions. The study and the treatment of the particulate, highly criticized for their potential impact on health, are the subject of numerous works of characterizations and developments. PSA Peugeot Citroen has recently (2000) launched its particulate filter technology on several types of vehicles (500,000 vehicles with DPF have been sold today). In order to evaluate the durability of this technology over a long period of time, a study program has been set-up by ADEME (French Environmental Agency), IFP Powertrain, PSA Peugeot Citroen and Taxis G7 (a Parisian taxis Company). The objective is to study the evolution of five taxis and their after-treatment system performances over 80,000km mileage--which corresponds to the recommended mileage before the first DPF maintenance--in hard urban driving conditions, as well over 120,000km, after the DPF maintenance and remanufacturing. More specifically, the following evaluations are being performed at regular intervals (around 20,000km): regulated gaseous pollutant emissions on NEDC cycle, particulate emissions and unregulated pollutant emissions. The results obtained until now have not shown any degradation of the particulate filter efficiency (more than 90%). This paper presents the methodology set-up, and the explanation of the first results obtained. Indeed, a more specific study has shown that most of the aerosols, measured with SMPS are composed of liquid fractions, mainly sulfates due to the sulphur coming from the fuel but also from the lubricant. The impact of sulfates stored on the catalyst surface during low temperature running phases and removed during high temperature running phases has been also outlined.« less

Did recent world record marathon runners employ optimal pacing strategies?

PubMed

Angus, Simon D

2014-01-01

We apply statistical analysis of high frequency (1 km) split data for the most recent two world-record marathon runs: Run 1 (2:03:59, 28 September 2008) and Run 2 (2:03:38, 25 September 2011). Based on studies in the endurance cycling literature, we develop two principles to approximate 'optimal' pacing in the field marathon. By utilising GPS and weather data, we test, and then de-trend, for each athlete's field response to gradient and headwind on course, recovering standardised proxies for power-based pacing traces. The resultant traces were analysed to ascertain if either runner followed optimal pacing principles; and characterise any deviations from optimality. Whereas gradient was insignificant, headwind was a significant factor in running speed variability for both runners, with Runner 2 targeting the (optimal) parallel variation principle, whilst Runner 1 did not. After adjusting for these responses, neither runner followed the (optimal) 'even' power pacing principle, with Runner 2's macro-pacing strategy fitting a sinusoidal oscillator with exponentially expanding envelope whilst Runner 1 followed a U-shaped, quadratic form. The study suggests that: (a) better pacing strategy could provide elite marathon runners with an economical pathway to significant performance improvements at world-record level; and (b) the data and analysis herein is consistent with a complex-adaptive model of power regulation.

The Effects of a 10-Kilometer Run on Muscle Strength and Power.

ERIC Educational Resources Information Center

Gomez, Ana L.; Radzwich, Robert J.; Denegar, Craig R.; Volek, Jeff S.; Rubin, Martyn R.; Bush, Jill A.; Doan, Brandon K.; Wickham, Robbin B.; Mazzetti, Scott A.; Newton, Robert U.; French, Duncan N.; Hakkinen, Keijo; Ratamess, Nicholas A.; Kraemer, William J.

2002-01-01

Investigated recovery of maximal force and power following a 10-km race. Data collected on 10 healthy male distance runners pre-race, immediately post-race, and 48 hours later indicated that strength and power capabilities of these 10-km runners were for the most part restored 48 hours after the race. Only the hamstring muscle group was not fully…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hagos, Samson M.; Feng, Zhe; Burleyson, Casey D.

Regional cloud permitting model simulations of cloud populations observed during the 2011 ARM Madden Julian Oscillation Investigation Experiment/ Dynamics of Madden-Julian Experiment (AMIE/DYNAMO) field campaign are evaluated against radar and ship-based measurements. Sensitivity of model simulated surface rain rate statistics to parameters and parameterization of hydrometeor sizes in five commonly used WRF microphysics schemes are examined. It is shown that at 2 km grid spacing, the model generally overestimates rain rate from large and deep convective cores. Sensitivity runs involving variation of parameters that affect rain drop or ice particle size distribution (more aggressive break-up process etc) generally reduce themore » bias in rain-rate and boundary layer temperature statistics as the smaller particles become more vulnerable to evaporation. Furthermore significant improvement in the convective rain-rate statistics is observed when the horizontal grid-spacing is reduced to 1 km and 0.5 km, while it is worsened when run at 4 km grid spacing as increased turbulence enhances evaporation. The results suggest modulation of evaporation processes, through parameterization of turbulent mixing and break-up of hydrometeors may provide a potential avenue for correcting cloud statistics and associated boundary layer temperature biases in regional and global cloud permitting model simulations.« less

Maximalist vs. minimalist shoes: dose-effect response of elastic compression on muscular oscillations.

PubMed

Gellaerts, Jules; Pirard, Maxime; Muzic, Jessie; Peseux, Maxime; Ménétrier, Arnaud

2017-10-01

The aim of this study was to establish whether maximalist shoes engender fewer muscular oscillations than minimalist shoes and determine to what extent these shoes, when combined with elastic compression (EC), help reduce muscle oscillations. For that purpose, we tested the effects of various levels of compression on the muscular oscillations in maximalist and minimalist footwear. Eleven volunteers executed 16 one-minute passages on a flat treadmill in a randomized order: maximalists or minimalists, walking (6 km/h) or running (10 km/h), without EC (control condition [CON]) or with EC applying different pressures (9.6 mmHg, 14.5 mmHg and 20.4 mmHg). The muscular oscillations were measured on both thighs, on the rectus femoris and on the vastus medialis with tri-axial accelerometers. Muscular oscillations are lower in maximalist shoes than in minimalist shoes, for both walking to 6 km/h and running to 10 km/h (P<0.05). Oscillations are also reduced with EC (P<0.05). This decrease is most marked when the pressure exercised by the EC is increased. Increased compression with minimalist shoes reduces muscular oscillations as much as maximalist shoes, when combined with lower compression.

Bi-Modal Micro-Cathode Arc Thruster for Cube Satellites

NASA Astrophysics Data System (ADS)

Chiu, Dereck

A new concept design, named the Bi-Modal Micro-Cathode Arc Thruster (BM-muCAT), has been introduced utilizing features from previous generations of muCATs and incorporating a multi-propellant functionality. This arc thruster is a micro-Newton level thruster based off of vacuum arc technology utilizing an enhanced magnetic field. Adjusting the magnetic field allows the thrusters performance to be varied. The goal of this thesis is to present a new generation of micro-cathode arc thrusters utilizing a bi-propellant, nickel and titanium, system. Three experimental procedures were run to test the new designs capabilities. Arc rotation experiment was used as a base experiment to ensure erosion was occurring uniformly along each electrode. Ion utilization efficiency was found, using an ion collector, to be up to 2% with the nickel material and 2.5% with the titanium material. Ion velocities were also studied using a time-of-flight method with an enhanced ion detection system. This system utilizes double electrostatic probes to measure plasma propagation. Ion velocities were measured to be 10km/s and 20km/s for nickel and titanium without a magnetic field. With an applied magnetic field of 0.2T, nickel ion velocities almost doubled to about 17km/s, while titanium ion velocities also increased to about 30km/s.

Gait characteristics over the course of a race in recreational marathon competitors.

PubMed

Bertram, John E A; Prebeau-Menezes, Leif; Szarko, Matthew J

2013-03-01

We analyzed gait and function of the supporting limb in participants of a marathon race at three stages: prerace, midrace (18 km), and near the end of the race (36 km). We confirmed that the most successful runners were able to maintain running speed for the duration of the race with little change in speed or gait. Speed slowed progressively during the race for those with slower race times, but stride frequency-stride length relationships remained normal for the speed they ran. These findings differ from most lab-based studies of fatigue, in which runners are forced to match a constant preset treadmill speed. Small changes in maximum ground force were seen in both slow- and fast-running participants as race end approached.

β-alanine supplementation improves tactical performance but not cognitive function in combat soldiers

PubMed Central

2014-01-01

Background There are no known studies that have examined β-alanine supplementation in military personnel. Considering the physiological and potential neurological effects that have been reported during sustained military operations, it appears that β-alanine supplementation may have a potential benefit in maintaining physical and cognitive performance during high-intensity military activity under stressful conditions. The purpose of this study was to examine the effect of 28 days of β-alanine ingestion in military personnel while fatigued on physical and cognitive performance. Methods Twenty soldiers (20.1 ± 0.9 years) from an elite combat unit were randomly assigned to either a β-alanine (BA) or placebo (PL) group. Soldiers were involved in advanced military training, including combat skill development, navigational training, self-defense/hand-to-hand combat and conditioning. All participants performed a 4-km run, 5-countermovement jumps using a linear position transducer, 120-m sprint, a 10-shot shooting protocol with assault rifle, including overcoming a misfire, and a 2-min serial subtraction test to assess cognitive function before (Pre) and after (Post) 28 days of supplementation. Results The training routine resulted in significant increases in 4-km run time for both groups, but no between group differences were seen (p = 0.597). Peak jump power at Post was greater for BA than PL (p = 0.034), while mean jump power for BA at Post was 10.2% greater (p = 0.139) than PL. BA had a significantly greater (p = 0.012) number of shots on target at Post (8.2 ± 1.0) than PL (6.5 ± 2.1), and their target engagement speed at Post was also significantly faster (p = 0.039). No difference in serial subtraction performance was seen between the groups (p = 0.844). Conclusion Results of this study indicate that 4-weeks of β-alanine ingestion in young, healthy soldiers did not impact cognitive performance, but did enhance power performance, marksmanship and target engagement speed from pre-ingestion levels. PMID:24716994

Estimation of Energy Expenditure during Treadmill Exercise via Thermal Imaging.

PubMed

Jensen, Martin Møller; Poulsen, Mathias Krogh; Alldieck, Thiemo; Larsen, Ryan Godsk; Gade, Rikke; Moeslund, Thomas Baltzer; Franch, Jesper

2016-12-01

Noninvasive imaging of oxygen uptake may provide a useful tool for the quantification of energy expenditure during human locomotion. A novel thermal imaging method (optical flow) was validated against indirect calorimetry for the estimation of energy expenditure during human walking and running. Fourteen endurance-trained subjects completed a discontinuous incremental exercise test on a treadmill. Subjects performed 4-min intervals at 3, 5, and 7 km·h (walking) and at 8, 10, 12, 14, 16, and 18 km·h (running) with 30 s of rest between intervals. Heart rate, gas exchange, and mean accelerations of ankle, thigh, wrist, and hip were measured throughout the exercise test. A thermal camera (30 frames per second) was used to quantify optical flow, calculated as the movements of the limbs relative to the trunk (internal mechanical work) and vertical movement of the trunk (external vertical mechanical work). Heart rate, gross oxygen uptake (mL·kg·min) together with gross and net energy expenditure (J·kg·min) rose with increasing treadmill velocities, as did optical flow measurements and mean accelerations (g) of ankle, thigh, wrist, and hip. Oxygen uptake was linearly correlated with optical flow across all exercise intensities (R = 0.96, P < 0.0001; V˙O2 [mL·kg·min] = 7.35 + 9.85 × optical flow [arbitrary units]). Only 3-4 s of camera recording was required to estimate an optical flow value at each velocity. Optical flow measurements provide an accurate estimation of energy expenditure during horizontal walking and running. The technique offers a novel experimental method of estimating energy expenditure during human locomotion, without use of interfering equipment attached to the subject.

Mixed-method pre-cooling reduces physiological demand without improving performance of medium-fast bowling in the heat.

PubMed

Minett, Geoffrey M; Duffield, Rob; Kellett, Aaron; Portus, Marc

2012-05-01

This study examined physiological and performance effects of pre-cooling on medium-fast bowling in the heat. Ten, medium-fast bowlers completed two randomised trials involving either cooling (mixed-methods) or control (no cooling) interventions before a 6-over bowling spell in 31.9±2.1°C and 63.5±9.3% relative humidity. Measures included bowling performance (ball speed, accuracy and run-up speeds), physical characteristics (global positioning system monitoring and counter-movement jump height), physiological (heart rate, core temperature, skin temperature and sweat loss), biochemical (serum concentrations of damage, stress and inflammation) and perceptual variables (perceived exertion and thermal sensation). Mean ball speed (114.5±7.1 vs. 114.1±7.2 km · h(-1); P = 0.63; d = 0.09), accuracy (43.1±10.6 vs. 44.2±12.5 AU; P = 0.76; d = 0.14) and total run-up speed (19.1±4.1 vs. 19.3±3.8 km · h(-1); P = 0.66; d = 0.06) did not differ between pre-cooling and control respectively; however 20-m sprint speed between overs was 5.9±7.3% greater at Over 4 after pre-cooling (P = 0.03; d = 0.75). Pre-cooling reduced skin temperature after the intervention period (P = 0.006; d = 2.28), core temperature and pre-over heart rates throughout (P = 0.01-0.04; d = 0.96-1.74) and sweat loss by 0.4±0.3 kg (P = 0.01; d = 0.34). Mean rating of perceived exertion and thermal sensation were lower during pre-cooling trials (P = 0.004-0.03; d = 0.77-3.13). Despite no observed improvement in bowling performance, pre-cooling maintained between-over sprint speeds and blunted physiological and perceptual demands to ease the thermoregulatory demands of medium-fast bowling in hot conditions.

Assessing Stride Variables and Vertical Stiffness with GPS-Embedded Accelerometers: Preliminary Insights for the Monitoring of Neuromuscular Fatigue on the Field

PubMed Central

Buchheit, Martin; Gray, Andrew; Morin, Jean-Benoit

2015-01-01

The aim of the present study was to examine the ability of a GPS-imbedded accelerometer to assess stride variables and vertical stiffness (K), which are directly related to neuromuscular fatigue during field-based high-intensity runs. The ability to detect stride imbalances was also examined. A team sport player performed a series of 30-s runs on an instrumented treadmill (6 runs at 10, 17 and 24 km·h-1) with or without his right ankle taped (aimed at creating a stride imbalance), while wearing on his back a commercially-available GPS unit with an embedded 100-Hz tri-axial accelerometer. Contact (CT) and flying (FT) time, and K were computed from both treadmill and accelerometers (Athletic Data Innovations) data. The agreement between treadmill (criterion measure) and accelerometer-derived data was examined. We also compared the ability of the different systems to detect the stride imbalance. Biases were small (CT and K) and moderate (FT). The typical error of the estimate was trivial (CT), small (K) and moderate (FT), with nearly perfect (CT and K) and large (FT) correlations for treadmill vs. accelerometer. The tape induced very large increase in the right - left foot ∆ in CT, FT and K measured by the treadmill. The tape effect on CT and K ∆ measured with the accelerometers were also very large, but of lower magnitude than with the treadmill. The tape effect on accelerometer-derived ∆ FT was unclear. Present data highlight the potential of a GPS-embedded accelerometer to assess CT and K during ground running. Key points GPS-embedded tri-axial accelerometers may be used to assess contact time and vertical stiffness during ground running. These preliminary results open new perspective for the field monitoring of neuromuscular fatigue and performance in run-based sports PMID:26664264

The EMEP MSC-W chemical transport model - technical description

NASA Astrophysics Data System (ADS)

Simpson, D.; Benedictow, A.; Berge, H.; Bergström, R.; Emberson, L. D.; Fagerli, H.; Flechard, C. R.; Hayman, G. D.; Gauss, M.; Jonson, J. E.; Jenkin, M. E.; Nyíri, A.; Richter, C.; Semeena, V. S.; Tsyro, S.; Tuovinen, J.-P.; Valdebenito, Á.; Wind, P.

2012-08-01

The Meteorological Synthesizing Centre-West (MSC-W) of the European Monitoring and Evaluation Programme (EMEP) has been performing model calculations in support of the Convention on Long Range Transboundary Air Pollution (CLRTAP) for more than 30 years. The EMEP MSC-W chemical transport model is still one of the key tools within European air pollution policy assessments. Traditionally, the model has covered all of Europe with a resolution of about 50 km × 50 km, and extending vertically from ground level to the tropopause (100 hPa). The model has changed extensively over the last ten years, however, with flexible processing of chemical schemes, meteorological inputs, and with nesting capability: the code is now applied on scales ranging from local (ca. 5 km grid size) to global (with 1 degree resolution). The model is used to simulate photo-oxidants and both inorganic and organic aerosols. In 2008 the EMEP model was released for the first time as public domain code, along with all required input data for model runs for one year. The second release of the EMEP MSC-W model became available in mid 2011, and a new release is targeted for summer 2012. This publication is intended to document this third release of the EMEP MSC-W model. The model formulations are given, along with details of input data-sets which are used, and a brief background on some of the choices made in the formulation is presented. The model code itself is available at www.emep.int, along with the data required to run for a full year over Europe.

The importance of wind-flux feedbacks during the November CINDY-DYNAMO MJO event

NASA Astrophysics Data System (ADS)

Riley Dellaripa, Emily; Maloney, Eric; van den Heever, Susan

2015-04-01

High-resolution, large-domain cloud resolving model (CRM) simulations probing the importance of wind-flux feedbacks to Madden-Julian Oscillation (MJO) convection are performed for the November 2011 CINDY-DYNAMO MJO event. The work is motivated by observational analysis from RAMA buoys in the Indian Ocean and TRMM precipitation retrievals that show a positive correlation between MJO precipitation and wind-induced surface fluxes, especially latent heat fluxes, during and beyond the CINDY-DYNAMO time period. Simulations are done using Colorado State University's Regional Atmospheric Modeling System (RAMS). The domain setup is oceanic and spans 1000 km x 1000 km with 1.5 km horizontal resolution and 65 stretched vertical levels centered on the location of Gan Island - one of the major CINDY-DYNAMO observation points. The model is initialized with ECMWF reanalysis and Aqua MODIS sea surface temperatures. Nudging from ECMWF reanalysis is applied at the domain periphery to encourage realistic evolution of MJO convection. The control experiment is run for the entire month of November so both suppressed and active, as well as, transitional phases of the MJO are modeled. In the control experiment, wind-induced surface fluxes are activated through the surface bulk aerodynamic formula and allowed to evolve organically. Sensitivity experiments are done by restarting the control run one week into the simulation and controlling the wind-induced flux feedbacks. In one sensitivity experiment, wind-induced surface flux feedbacks are completely denied, while in another experiment the winds are kept constant at the control simulations mean surface wind speed. The evolution of convection, especially on the mesoscale, is compared between the control and sensitivity simulations.

United States Army physical readiness training: rationale and evaluation of the physical training doctrine.

PubMed

Knapik, Joseph J; Rieger, William; Palkoska, Frank; Van Camp, Steven; Darakjy, Salima

2009-07-01

This paper reviews the rationale and evaluations of Physical Readiness Training (PRT), the new U.S. Army physical training doctrine designed to improve soldiers' physical capability for military operations. The purposes of PRT are to improve physical fitness, prevent injuries, progressively train soldiers, and develop soldiers' self-confidence and discipline. The PRT follows the principles of progressive overload, regularity, specificity, precision, variety, and balance. Specificity was achieved by examining the standard list of military (warrior) tasks and determining 1) the physical requirements, 2) the fitness components involved, and 3) the training activities that most likely could improve the military tasks. Injury-prevention features include reduced running mileage, exercise variety (cross-training), and gradual, progressive training. In 3 military field studies, the overall adjusted risk of injury was 1.5-1.8 times higher in groups of soldiers performing traditional military physical training programs when compared with groups using a PRT program. Scores on the Army Physical Fitness Test were similar or higher in groups using PRT programs. In an 8-week laboratory study comparing PRT with a weightlifting/running program, both programs resulted in major improvements in militarily relevant tasks (e.g., 3.2-km walk/run with 32-kg load, 400-m run with 18-kg load, 5- to 30-second rushes to and from prone position, 80-kg casualty drag, obstacle course). When compared with traditional military physical training programs, PRT consistently resulted in fewer injuries and in equal or greater improvements in fitness and military task performance.

Non-exchangeability of running vs. other exercise in their association with adiposity, and its implications for public health recommendations.

PubMed

Williams, Paul T

2012-01-01

Current physical activity recommendations assume that different activities can be exchanged to produce the same weight-control benefits so long as total energy expended remains the same (exchangeability premise). To this end, they recommend calculating energy expenditure as the product of the time spent performing each activity and the activity's metabolic equivalents (MET), which may be summed to achieve target levels. The validity of the exchangeability premise was assessed using data from the National Runners' Health Study. Physical activity dose was compared to body mass index (BMI) and body circumferences in 33,374 runners who reported usual distance run and pace, and usual times spent running and other exercises per week. MET hours per day (METhr/d) from running was computed from: a) time and intensity, and b) reported distance run (1.02 MET • hours per km). When computed from time and intensity, the declines (slope±SE) per METhr/d were significantly greater (P<10(-15)) for running than non-running exercise for BMI (slopes±SE, male: -0.12 ± 0.00 vs. 0.00±0.00; female: -0.12 ± 0.00 vs. -0.01 ± 0.01 kg/m(2) per METhr/d) and waist circumference (male: -0.28 ± 0.01 vs. -0.07±0.01; female: -0. 31±0.01 vs. -0.05 ± 0.01 cm per METhr/d). Reported METhr/d of running was 38% to 43% greater when calculated from time and intensity than distance. Moreover, the declines per METhr/d run were significantly greater when estimated from reported distance for BMI (males: -0.29 ± 0.01; females: -0.27 ± 0.01 kg/m(2) per METhr/d) and waist circumference (males: -0.67 ± 0.02; females: -0.69 ± 0.02 cm per METhr/d) than when computed from time and intensity (cited above). The exchangeability premise was not supported for running vs. non-running exercise. Moreover, distance-based running prescriptions may provide better weight control than time-based prescriptions for running or other activities. Additional longitudinal studies and randomized clinical trials are required to verify these results prospectively.

Experience with the ULISS-30 inertial survey system for local geodetic and cadastral network control

NASA Astrophysics Data System (ADS)

Forsberg, Rene

1991-09-01

The capability of the recently developed SAGEM ULISS-30 inertial survey system for performing local surveys at high accuracies have been tested in a field campaign carried out November 1989 on the island of Fyn, Denmark, in cooperation with the Swedish National Land Survey. In the test a number of lines between existing national geodetic control points were surveyed, along with points in the less reliably determined cadastral network, forming an irregular network pattern of 10 15 km extent. The survey involved frequent offset measurements (up to 50 100 m) with an ISS-integrated total station. The profile geometries were not particularly suited for inertial surveys, with narrow and rather winding roads, necessitating frequent vehicle turns. In addition to the pure inertial surveys a kinematic GPS/inertial test was also carried out, using a pair of Ashtech L-XII receivers. The inertial survey results, analyzed with a smoothing algoritm utilizing common points on forward/backward runs, indicate that 5-cm accuracies are possible on reasonably straight profiles of 5 km length, corresponding to a 10 ppm “best-case” accuracy for double-run traverses. On longer, more winding traverses error levels of 10 20 cm are typical. To handle the inertial data optimally, proper network adjustments are required. A discussion of suitable adjustment models of both conventional and collocation type is included in the paper.

Using broadband spatially resolved NIRS to assess muscle oxygenation during altered running protocols

NASA Astrophysics Data System (ADS)

Koukourakis, Georg; Vafiadou, Maria; Steimers, André; Geraskin, Dmitri; Neary, Patrick; Kohl-Bareis, Matthias

2009-07-01

We used spatially resolved near-infrared spectroscopy (SRS-NIRS) to assess calf and thigh muscle oxygenation during running on a motor-driven treadmill. Two protocols were used: An incremental speed protocol (velocity = 6 - 12 km/h, ▵v = 2 km/h) was performed in 3 minute stages, while a pacing paradigm modulated step frequency alternatively (2.3 Hz [SLow]; 3.3 Hz [SHigh]) during a constant velocity for 2 minutes each. A SRS-NIRS broadband system (600 - 1000 nm) was used to measure total haemoglobin concentration and oxygen saturation (SO2). An accelerometer was placed on the hip joints to measure limb acceleration through the experiment. The data showed that the calf (SO2 58 to 42%) desaturated to a significantly lower level than the thigh (61 to 54%). During the pacing protocol, SO2 was significantly different between the SLow vs. SHigh trials. Additionally, physiological data as measured by spirometry were different between the SLow vs. SHigh pacing trials (VO2 (2563+/- 586 vs. 2503 +/- 605 mL/min). Significant differences in VO2 at the same workload (speed) indicate alterations in mechanical efficiency. These data suggest that SRS broadband NIRS can be used to discern small changes in muscle oxygenation, making this device useful for metabolic exercise studies in addition to spirometry and movement monitoring by accelerometers.

Evaluation of predicted diurnal cycle of precipitation after tests with convection and microphysics schemes in the Eta Model

NASA Astrophysics Data System (ADS)

Gomes, J. L.; Chou, S. C.; Yaguchi, S. M.

2012-04-01

Physics parameterizations and the model vertical and horizontal resolutions, for example, can significantly contribute to the uncertainty in the numerical weather predictions, especially at regions with complex topography. The objective of this study is to assess the influences of model precipitation production schemes and horizontal resolution on the diurnal cycle of precipitation in the Eta Model . The model was run in hydrostatic mode at 3- and 5-km grid sizes, the vertical resolution was set to 50 layers, and the time steps to 6 and 10 s, respectively. The initial and boundary conditions were taken from ERA-Interim reanalysis. Over the sea the 0.25-deg sea surface temperature from NOAA was used. The model was setup to run for each resolution over Angra dos Reis, located in the Southeast region of Brazil, for the rainy period between 18 December 2009 and 01 de January 2010, the model simulation range was 48 hours. In one set of runs the cumulus parameterization was switched off, in this case the model precipitation was fully simulated by cloud microphysics scheme, and in the other set the model was run with weak cumulus convection. The results show that as the model horizontal resolution increases from 5 to 3 km, the spatial pattern of the precipitation hardly changed, although the maximum precipitation core increased in magnitude. Daily data from automatic station data was used to evaluate the runs and shows that the diurnal cycle of temperature and precipitation were better simulated for 3 km when compared against observations. The model configuration results without cumulus convection shows a small contraction in the precipitating area and an increase in the simulated maximum values. The diurnal cycle of precipitation was better simulated with some activity of the cumulus convection scheme. The skill scores for the period and for different forecast ranges are higher at weak and moderate precipitation rates.

Ibuprofen does not affect serum electrolyte concentrations after an ultradistance run

PubMed Central

Dumke, Charles L; Nieman, David C; Oley, Kevin; Lind, Robert H

2007-01-01

Objective To determine the effects of ibuprofen on serum electrolyte concentrations after a 160 km running race. Methods Twenty nine subjects (mean (SD) age 47.9 (7.4) years) ingested 600 mg ibuprofen the day before, and 1200 mg ibuprofen during, a 160 km competitive trail running race (approximately every 4 h in 200 mg doses). Twenty five control subjects (mean (SD) age 46.8 (10.3) years) avoided ingestion of ibuprofen before or during the race. Blood was drawn on the day before the race and immediately after the race. Serum biochemical profiles were analysed by a clinical laboratory. Significant effects of treatment and time were determined with a general linear model with repeated measures. Results Subjects in the two groups did not differ by age, training volume, race experience, body mass index, body fat, or finishing time (25.8 (3.3) vs 25.6 (3.9) h). Body weight did not change significantly over the race (measured before, mid‐race (90 km), and after). Ibuprofen ingestion did not significantly affect any of the serum markers including creatine kinase (p = 0.16). A significant decrease in serum sodium (p = 0.006), potassium (p = 0.001), chloride (p<0.001), calcium (p<0.001), albumin (p<0.001) and globulin (p<0.001) was observed after the race. Increases were seen in creatine kinase (p<0.001), creatinine (p<0.001), blood urea nitrogen (p<0.001), uric acid (p<0.001) and glucose (p<0.001) as the result of the race. Conclusions These data suggest that the non‐specific cyclo‐oxygenase inhibitor, ibuprofen, does not alter serum electrolyte concentrations during ultradistance running. However, the stress of ultradistance running appears to be related to significant changes in certain serum markers. PMID:17331976

Running Pace Decrease during a Marathon Is Positively Related to Blood Markers of Muscle Damage

PubMed Central

Del Coso, Juan; Fernández, David; Abián-Vicen, Javier; Salinero, Juan José; González-Millán, Cristina; Areces, Francisco; Ruiz, Diana; Gallo, César; Calleja-González, Julio; Pérez-González, Benito

2013-01-01

Background Completing a marathon is one of the most challenging sports activities, yet the source of running fatigue during this event is not completely understood. The aim of this investigation was to determine the cause(s) of running fatigue during a marathon in warm weather. Methodology/Principal Findings We recruited 40 amateur runners (34 men and 6 women) for the study. Before the race, body core temperature, body mass, leg muscle power output during a countermovement jump, and blood samples were obtained. During the marathon (27 °C; 27% relative humidity) running fatigue was measured as the pace reduction from the first 5-km to the end of the race. Within 3 min after the marathon, the same pre-exercise variables were obtained. Results Marathoners reduced their running pace from 3.5 ± 0.4 m/s after 5-km to 2.9 ± 0.6 m/s at the end of the race (P<0.05), although the running fatigue experienced by the marathoners was uneven. Marathoners with greater running fatigue (> 15% pace reduction) had elevated post-race myoglobin (1318 ± 1411 v 623 ± 391 µg L−1; P<0.05), lactate dehydrogenase (687 ± 151 v 583 ± 117 U L−1; P<0.05), and creatine kinase (564 ± 469 v 363 ± 158 U L−1; P = 0.07) in comparison with marathoners that preserved their running pace reasonably well throughout the race. However, they did not differ in their body mass change (−3.1 ± 1.0 v −3.0 ± 1.0%; P = 0.60) or post-race body temperature (38.7 ± 0.7 v 38.9 ± 0.9 °C; P = 0.35). Conclusions/Significance Running pace decline during a marathon was positively related with muscle breakdown blood markers. To elucidate if muscle damage during a marathon is related to mechanistic or metabolic factors requires further investigation. PMID:23460881

Clouds in ECMWF's 30 KM Resolution Global Atmospheric Forecast Model (TL639)

NASA Technical Reports Server (NTRS)

Cahalan, R. F.; Morcrette, J. J.

1999-01-01

Global models of the general circulation of the atmosphere resolve a wide range of length scales, and in particular cloud structures extend from planetary scales to the smallest scales resolvable, now down to 30 km in state-of-the-art models. Even the highest resolution models do not resolve small-scale cloud phenomena seen, for example, in Landsat and other high-resolution satellite images of clouds. Unresolved small-scale disturbances often grow into larger ones through non-linear processes that transfer energy upscale. Understanding upscale cascades is of crucial importance in predicting current weather, and in parameterizing cloud-radiative processes that control long term climate. Several movie animations provide examples of the temporal and spatial variation of cloud fields produced in 4-day runs of the forecast model at the European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading, England, at particular times and locations of simultaneous measurement field campaigns. model resolution is approximately 30 km horizontally (triangular truncation TL639) with 31 vertical levels from surface to stratosphere. Timestep of the model is about 10 minutes, but animation frames are 3 hours apart, at timesteps when the radiation is computed. The animations were prepared from an archive of several 4-day runs at the highest available model resolution, and archived at ECMWF. Cloud, wind and temperature fields in an approximately 1000 km X 1000 km box were retrieved from the archive, then approximately 60 Mb Vis5d files were prepared with the help of Graeme Kelly of ECMWF, and were compressed into MPEG files each less than 3 Mb. We discuss the interaction of clouds and radiation in the model, and compare the variability of cloud liquid as a function of scale to that seen in cloud observations made in intensive field campaigns. Comparison of high-resolution global runs to cloud-resolving models, and to lower resolution climate models is leading to better understanding of the upscale cascade and suggesting new cloud-radiation parameterizations for climate models.

High resolution simulations of orographic flow over a complex terrain on the Southeast coast of Brazil

NASA Astrophysics Data System (ADS)

Chou, S. C.; Zolino, M. M.; Gomes, J. L.; Bustamante, J. F.; Lima-e-Silva, P. P.

2012-04-01

The Eta Model is used operationally by CPTEC to produce weather forecasts over South America since 1997. The model has gone through upgrades. In order to prepare the model for operational higher resolution forecasts, the model is configured and tested over a region of complex topography located near the coast of Southeast Brazil. The Eta Model was configured, with 2-km horizontal resolution and 50 layers. The Eta-2km is a second nesting, it is driven by Eta-15km, which in its turn is driven by Era-Interim reanalyses. The model domain includes the two Brazilians cities, Rio de Janeiro and Sao Paulo, urban areas, preserved tropical forest, pasture fields, and complex terrain and coastline. Mountains can rise up to about 700m. The region suffers frequent events of floods and landslides. The objective of this work is to evaluate high resolution simulations of wind and temperature in this complex area. Verification of model runs uses observations taken from the nuclear power plant. Accurate near-surface wind direction and magnitude are needed for the plant emergency plan and winds are highly sensitive to model spatial resolution and atmospheric stability. Verification of two cases during summer shows that model has clear diurnal cycle signal for wind in that region. The area is characterized by weak winds which makes the simulation more difficult. The simulated wind magnitude is about 1.5m/s, which is close to observations of about 2m/s; however, the observed change of wind direction of the sea breeze is fast whereas it is slow in the simulations. Nighttime katabatic flow is captured by the simulations. Comparison against Eta-5km runs show that the valley circulation is better described in the 2-km resolution run. Simulated temperatures follow closely the observed diurnal cycle. Experiments improving some surface conditions such as the surface temperature and land cover show simulation error reduction and improved diurnal cycle.

Monitoring Air Quality over China: Evaluation of the modeling system of the PANDA project

NASA Astrophysics Data System (ADS)

Bouarar, Idir; Katinka Petersen, Anna; Brasseur, Guy; Granier, Claire; Xie, Ying; Wang, Xuemei; Fan, Qi; Wang, Lili

2015-04-01

Air pollution has become a pressing problem in Asia and specifically in China due to rapid increase in anthropogenic emissions related to growth of China's economic activity and increasing demand for energy in the past decade. Observed levels of particulate matter and ozone regularly exceed World Health Organization (WHO) air quality guidelines in many parts of the country leading to increased risk of respiratory illnesses and other health problems. The EU-funded project PANDA aims to establish a team of European and Chinese scientists to monitor air pollution over China and elaborate air quality indicators in support of European and Chinese policies. PANDA combines state-of-the-art air pollution modeling with space and surface observations of chemical species to improve methods for monitoring air quality. The modeling system of the PANDA project follows a downscaling approach: global models such as MOZART and MACC system provide initial and boundary conditions to regional WRF-Chem and EMEP simulations over East Asia. WRF-Chem simulations at higher resolution (e.g. 20km) are then performed over a smaller domain covering East China and initial and boundary conditions from this run are used to perform simulations at a finer resolution (e.g. 5km) over specific megacities like Shanghai. Here we present results of model simulations for January and July 2010 performed during the first year of the project. We show an intercomparison of the global (MACC, EMEP) and regional (WRF-Chem) simulations and a comprehensive evaluation with satellite measurements (NO2, CO) and in-situ data (O3, CO, NOx, PM10 and PM2.5) at several surface stations. Using the WRF-Chem model, we demonstrate that model performance is influenced not only by the resolution (e.g. 60km, 20km) but also the emission inventories used (MACCity, HTAPv2), their resolution and diurnal variation, and the choice of initial and boundary conditions (e.g. MOZART, MACC analysis).

SENSITIVITY OF THE REGIONAL WATER BALANCE IN THE COLUMBIA RIVER BASIN TO CLIMATE VARIABILITY: APPLICATION OF A SPATIALLY DISTRIBUTED WATER BALANCE MODEL

EPA Science Inventory

A one-dimensional water balance model was developed and used to simulate water balance for the Columbia River Basin. he model was run over a 10 km X 10 km grid for the United State's portion of the basin. he regional water balance was calculated using a monthly time-step for a re...

Gait Characteristics over the Course of a Race in Recreational Marathon Competitors

ERIC Educational Resources Information Center

Bertram, John E. A.; Prebeau-Menezes, Leif; Szarko, Matthew J.

2013-01-01

We analyzed gait and function of the supporting limb in participants of a marathon race at three stages: prerace, midrace (18 km), and near the end of the race (36 km). We confirmed that the most successful runners were able to maintain running speed for the duration of the race with little change in speed or gait. Speed slowed progressively…

The Vertical Transport in the Ocean: a Pump Driven by Meso and Submesoscale Structures

NASA Astrophysics Data System (ADS)

Rosso, I.; Hogg, A. M.; Strutton, P. G.; Kiss, A. E.

2012-04-01

The upper ocean can be considered as a vehicle for the exchange of gases between air and the deep ocean. Furthermore, the transport of nutrients through the mixed layer occurs via a combination of biogeochemical and physical pumps; both of these mechanisms play a fundamental role in the carbon cycle. In the surface layer phytoplankton convert carbon dioxide into organic compounds using nutrients and light. Nutrients, which are depleted at the surface, can be transported into the mixed layer by vertical motion; recently, it has been discovered that this vertical transport is more often associated with submesoscale fronts of O(10) km (rather than inside mesoscale structures, of O(100) km, like eddies). At the submesoscale fronts, rates of O(100) m day-1 can emerge, particularly high compared to values of 10 m/day found at the mesoscales [M. Lèvy, et al. J. Mar. Res., 2001]. At this fine scale, the vertical transport of nutrients is highly effective, upwelling waters from the depth rich of nutrients and downwelling depleted waters from the surface. The fine-scale vertical transport mechanism has recently become of great interest, though is not completely understood. We investigate the dynamics and the transport of tracers at the meso and sub-mesoscales by running numerical simulations with a domain of 1024 km x 512 km x 1600 m, at 3 different resolutions: 8 km, 4km and 1km. We use the MIT general circulation model with free surface, linear bottom drag and free slip condition at the north and south walls. Non-linear 3rd order advection scheme and biharmonic viscosity are applied. Furthermore, the fluid is forced by a constant zonal wind stress. The flow is zonally periodic and presents an idealized topography. We started from an initial vertical stratification and run the model to reach an equilibrium flow state. A passive tracer is released after the equilibrium is reached. We investigate how the fine scales are affecting the rate of vertical transport and the distribution of the tracer. We show that also the presence of the topography has an impact in driving this transport. Furthermore, the model can run in a non-hydrostatic configuration, allowing us to investigate the effect of this parameterization on the transport.

An Overview of Numerical Weather Prediction on Various Scales

NASA Astrophysics Data System (ADS)

Bao, J.-W.

2009-04-01

The increasing public need for detailed weather forecasts, along with the advances in computer technology, has motivated many research institutes and national weather forecasting centers to develop and run global as well as regional numerical weather prediction (NWP) models at high resolutions (i.e., with horizontal resolutions of ~10 km or higher for global models and 1 km or higher for regional models, and with ~60 vertical levels or higher). The need for running NWP models at high horizontal and vertical resolutions requires the implementation of non-hydrostatic dynamic core with a choice of horizontal grid configurations and vertical coordinates that are appropriate for high resolutions. Development of advanced numerics will also be needed for high resolution global and regional models, in particular, when the models are applied to transport problems and air quality applications. In addition to the challenges in numerics, the NWP community is also facing the challenges of developing physics parameterizations that are well suited for high-resolution NWP models. For example, when NWP models are run at resolutions of ~5 km or higher, the use of much more detailed microphysics parameterizations than those currently used in NWP model will become important. Another example is that regional NWP models at ~1 km or higher only partially resolve convective energy containing eddies in the lower troposphere. Parameterizations to account for the subgrid diffusion associated with unresolved turbulence still need to be developed. Further, physically sound parameterizations for air-sea interaction will be a critical component for tropical NWP models, particularly for hurricane predictions models. In this review presentation, the above issues will be elaborated on and the approaches to address them will be discussed.

Kinematic, Cardiopulmonary, and Metabolic Responses of Overweight Runners While Running at Self-Selected and Standardized Speeds

PubMed Central

Zdziarski, Laura Ann; Chen, Cong; Horodyski, Marybeth; Vincent, Kevin R.; Vincent, Heather K.

2017-01-01

Objective To determine the differences in kinematic, cardiopulmonary, and metabolic responses between overweight and healthy weight runners at a self-selected and standard running speed. Design Comparative descriptive study. Setting Tertiary care institution, university-affiliated research laboratory. Participants Overweight runners (n = 21) were matched with runners of healthy weight (n = 42). Methods Participants ran at self-selected and standardized speeds (13.6 km/h). Sagittal plane joint kinematics were captured simultaneously with cardiopulmonary and metabolic measures using a motion capture system and portable gas analyzer, respectively. Main Outcome Measurements Spatiotemporal parameters (cadence, step width and length, center of gravity displacement, stance time) joint kinematics, oxygen cost, heart rate, ventilation and energy expenditure. Results At the self-selected speed, overweight individuals ran slower (8.5 ± 1.3 versus 10.0 ± 1.6 km/h) and had slower cadence (163 versus 169 steps/min; P < .05). The sagittal plane range of motion (ROM) for flexion-extension at the ankle, knee, hip, and anterior pelvic tilt were all less in overweight runners compared to healthy weight runners (all P < .05). At self-selected speed and 13.6 km/h, energy expenditure was higher in the overweight runners compared to their healthy weight counterparts (P < .05). At 13.6 km/h, only the frontal hip and pelvis ROM were higher in the overweight versus the healthy weight runners (P < .05), and energy expenditure, net energy cost, and minute ventilation were higher in the overweight runners compared to the healthy weight runners (P < .05). Conclusion At self-selected running speeds, the overweight runners demonstrated gait strategies (less joint ROM, less vertical displacement, and shorter step lengths) that resulted in cardiopulmonary and energetic responses similar to those of healthy weight individuals. PMID:26146194

The effect of muscle fatigue on in vivo tibial strains.

PubMed

Milgrom, Charles; Radeva-Petrova, Denitsa R; Finestone, Aharon; Nyska, Meir; Mendelson, Stephen; Benjuya, Nisim; Simkin, Ariel; Burr, David

2007-01-01

Stress fracture is a common musculoskeletal problem affecting athletes and soldiers. Repetitive high bone strains and strain rates are considered to be its etiology. The strain level necessary to cause fatigue failure of bone ex vivo is higher than the strains recorded in humans during vigorous physical activity. We hypothesized that during fatiguing exercises, bone strains may increase and reach levels exceeding those measured in the non-fatigued state. To test this hypothesis, we measured in vivo tibial strains, the maximum gastrocnemius isokinetic torque and ground reaction forces in four subjects before and after two fatiguing levels of exercise: a 2km run and a 30km desert march. Strains were measured using strain-gauged staples inserted percutaneously in the medial aspect of their mid-tibial diaphysis. There was a decrease in the peak gastrocnemius isokinetic torque of all four subjects' post-march as compared to pre-run (p=0.0001), indicating the presence of gastrocnemius muscle fatigue. Tension strains increased 26% post-run (p=0.002, 95 % confidence interval (CI) and 29% post-march (p=0.0002, 95% CI) as compared to the pre-run phase. Tension strain rates increased 13% post-run (p=0.001, 95% CI) and 11% post-march (p=0.009, 95% CI) and the compression strain rates increased 9% post-run (p=0.0004, 95% CI) and 17% post-march (p=0.0001, 95% CI). The fatigue state increases bone strains well above those recorded in rested individuals and may be a major factor in the stress fracture etiology.

Metabolic power demands of rugby league match play.

PubMed

Kempton, Tom; Sirotic, Anita Claire; Rampinini, Ermanno; Coutts, Aaron James

2015-01-01

To describe the metabolic demands of rugby league match play for positional groups and compare match distances obtained from high-speed-running classifications with those derived from high metabolic power. Global positioning system (GPS) data were collected from 25 players from a team competing in the National Rugby League competition over 39 matches. Players were classified into positional groups (adjustables, outside backs, hit-up forwards, and wide-running forwards). The GPS devices provided instantaneous raw velocity data at 5 Hz, which were exported to a customized spreadsheet. The spreadsheet provided calculations for speed-based distances (eg, total distance; high-speed running, >14.4 km/h; and very-high-speed running, >18.1 km/h) and metabolic-power variables (eg, energy expenditure; average metabolic power; and high-power distance, >20 W/kg). The data show that speed-based distances and metabolic power varied between positional groups, although this was largely related to differences in time spent on field. The distance covered at high running speed was lower than that obtained from high-power thresholds for all positional groups; however, the difference between the 2 methods was greatest for hit-up forwards and adjustables. Positional differences existed for all metabolic parameters, although these are at least partially related to time spent on the field. Higher-speed running may underestimate the demands of match play when compared with high-power distance-although the degree of difference between the measures varied by position. The analysis of metabolic power may complement traditional speed-based classifications and improve our understanding of the demands of rugby league match play.

Preventing running-related injuries using evidence-based online advice: the design of a randomised-controlled trial

PubMed Central

de Vos, Robert-Jan; van Ochten, John M; Verhaar, Jan AN; Davis, Irene S; Bindels, Patrick JE; Bierma-Zeinstra, Sita MA; van Middelkoop, Marienke

2017-01-01

Introduction Running-related injuries (RRIs) are frequent and can lead to cessation of health promoting activities. Several risk factors for RRIs have been identified. However, no successful injury prevention programme has been developed so far. Therefore, the aim of the present study is to investigate the effect of an evidence-based online injury prevention programme on the number of RRIs. Methods and analysis The INSPIRE trial is a randomised-controlled trial with a 3-month follow-up. Both novice and more experienced runners, aged 18 years and older, who register for a running event (distances 5 km up to 42.195 km) will be asked to participate in this study. After completing the baseline questionnaire, participants will be randomised into either the intervention group or control group. Participants in the intervention group will get access to the online injury prevention programme. This prevention programme consists of information on evidence-based risk factors and advices to reduce the injury risk. The primary outcome measure is the number of self-reported RRIs in the time frame between registration for a running event and 1 month after the running event. Secondary outcome measures include the running days missed due to injuries, absence of work or school due to injuries, and the injury location. Ethics and dissemination An exemption for a comprehensive application is obtained by the Medical Ethical Committee of the Erasmus University Medical Centre Rotterdam, Netherlands. The results of the study will be published in peer-reviewed journals and presented on international congresses. Trial registration number NTR5998. Pre-results PMID:28761721

Evaluation of the 7-km GEOS-5 Nature Run

NASA Technical Reports Server (NTRS)

Gelaro, Ronald; Putman, William M.; Pawson, Steven; Draper, Clara; Molod, Andrea; Norris, Peter M.; Ott, Lesley; Prive, Nikki; Reale, Oreste; Achuthavarier, Deepthi;

Evaluation of the high resolution DEHM/UBM model system over Denmark

NASA Astrophysics Data System (ADS)

Im, Ulas; Christensen, Jesper H.; Ellermann, Thomas; Ketzel, Matthias; Geels, Camilla; Hansen, Kaj M.; Plejdrup, Marlene S.; Brandt, Jørgen

2015-04-01

The air pollutant levels over Denmark are simulated using the high resolution DEHM/UBM model system for the years 2006 to 2014. The system employs a hemispheric chemistry-transport model, the Danish Eulerian Hemispheric Model (DEHM; Brandt et al., 2012) that runs on a 150 km x 150 km resolution over the Northern Hemisphere, with nesting capability for higher resolutions over Europe, Northern Europe and Denmark on 50 km x 50 km, 16.7 km x 16.7 km and 5.6 km x 5.6 km resolutions, respectively, coupled to the Urban Background Model (UBM; Berkowicz, 2000; Brandt et al., 2001) that covers the whole of Denmark with a 1 km x 1 km spatial resolution. Over Denmark, the system uses the SPREAD emission model (Plejdrup and Gyldenkærne, 2011) that distributes the Danish emissions for all pollutants and all sectors in the national emission database on a 1 km x 1 km resolution grid covering Denmark and its national sea territory. The study will describe the model system and we will evaluate the performance of the model system in simulating hourly and daily ozone (O3), carbon monoxide (CO), nitrogen monoxide (NO), nitrogen dioxide (NO2) and particulate matter (PM10 and PM2.5) concentrations against surface measurements from eight monitoring stations. Finally we investigate the spatial variation of air pollutants over Denmark on different time scales. References Berkowicz, R., 2000. A Simple Model for Urban Background Pollution. Environmental Monitoring and Assessment, 65, 1/2, 259-267. Brandt, J., J. H. Christensen, L. M. Frohn, F. Palmgren, R. Berkowicz and Z. Zlatev, 2001: "Operational air pollution forecasts from European to local scale". Atmospheric Environment, Vol. 35, Sup. No. 1, pp. S91-S98, 2001 Brandt et al., 2012. An integrated model study for Europe and North America using the Danish Eulerian Hemispheric Model with focus on intercontinental transport. Atmospheric Environment, 53, 156-176. Plejdrup, M.S., Gyldenkærne, S., 2011. Spatial distribution of pollutants to air - the SPREAD model. NERI Technical Report No. 823.

Sensitivity of sea-level forecasting to the horizontal resolution and sea surface forcing for different configurations of an oceanographic model of the Adriatic Sea

NASA Astrophysics Data System (ADS)

Bressan, Lidia; Valentini, Andrea; Paccagnella, Tiziana; Montani, Andrea; Marsigli, Chiara; Stefania Tesini, Maria

2017-04-01

At the Hydro-meteo-climate service of the Regional environmental agency of Emilia-Romagna, Italy (Arpae-SIMC), the oceanographic numerical model AdriaROMS is used in the operational forecasting suite to compute sea level, temperature, salinity and 3-D current fields of the Adriatic Sea (northern Mediterranean Sea). In order to evaluate the performance of the sea-level forecast and to study different configurations of the ROMS model, two marine storms occurred on the Emilia Romagna coast during the winter 2015-2016 are investigated. The main focus of this study is to analyse the sensitivity of the model to the horizontal resolution and to the meteorological forcing. To this end, the model is run with two different configurations and with two horizontal grids at 1 and 2 km resolution. To study the influence of the meteorological forcing, the two storms have been reproduced by running ROMS in ensemble mode, forced by the 16-members of the meteorological ensemble COSMO-LEPS system. Possible optimizations of the model set-up are deduced by the comparison of the different run outputs.

Enhancing physical performance in elite junior tennis players with a caffeinated energy drink.

PubMed

Gallo-Salazar, César; Areces, Francisco; Abián-Vicén, Javier; Lara, Beatriz; Salinero, Juan José; Gonzalez-Millán, Cristina; Portillo, Javier; Muñoz, Victor; Juarez, Daniel; Del Coso, Juan

2015-04-01

The aim of this study was to investigate the effectiveness of a caffeinated energy drink to enhance physical performance in elite junior tennis players. In 2 different sessions separated by 1 wk, 14 young (16 ± 1 y) elite-level tennis players ingested 3 mg caffeine per kg body mass in the form of an energy drink or the same drink without caffeine (placebo). After 60 min, participants performed a handgrip-strength test, a maximal-velocity serving test, and an 8 × 15-m sprint test and then played a simulated singles match (best of 3 sets). Instantaneous running speed during the matches was assessed using global positioning (GPS) devices. Furthermore, the matches were videotaped and notated afterward. In comparison with the placebo drink, the ingestion of the caffeinated energy drink increased handgrip force by ~4.2% ± 7.2% (P = .03) in both hands, the running pace at high intensity (46.7 ± 28.5 vs 63.3 ± 27.7 m/h, P = .02), and the number of sprints (12.1 ± 1.7 vs 13.2 ± 1.7, P = .05) during the simulated match. There was a tendency for increased maximal running velocity during the sprint test (22.3 ± 2.0 vs 22.9 ± 2.1 km/h, P = .07) and higher percentage of points won on service with the caffeinated energy drink (49.7% ± 9.8% vs 56.4% ± 10.0%, P = .07) in comparison with the placebo drink. The energy drink did not improve ball velocity during the serving test (42.6 ± 4.8 vs 42.7 ± 5.0 m/s, P = .49). The preexercise ingestion of caffeinated energy drinks was effective to enhance some aspects of physical performance of elite junior tennis players.

Muscle enzyme release does not predict muscle function impairment after triathlon.

PubMed

Margaritis, I; Tessier, F; Verdera, F; Bermon, S; Marconnet, P

1999-06-01

We sought to determine the effects of a long distance triathlon (4 km swim, 120 km bike-ride, and 30 km run) on the four-day kinetics of the biochemical markers of muscle damage, and whether they were quantitatively linked with muscle function impairment and soreness. Data were collected from 2 days before until 4 days after the completion of the race. Twelve triathletes performed the triathlon and five did not. Maximal voluntary contraction (MVC), muscle soreness (DOMS) and total serum CK, CK-MB, LDH, AST and ALT activities were assessed. Significant changes after triathlon completion were found for all muscle damage indirect markers over time (p < 0.0001). MVC of the knee extensor and flexor muscles decreased over time (p < 0.05). There is disparity in the time point at which peak values where reached for DOMS, MVC and enzyme leakage. There is no correlation between serum enzyme leakage, DOMS and MVC impairment which occur after triathlon. Long distance triathlon race caused muscle damage, but extent, as well as muscle recovery cannot be evaluated by the magnitude of changes in serum enzyme activities. Muscle enzyme release cannot be used to predict the magnitude of the muscle function impairment caused by muscle damage.

Optical effects produced by running onboard engines of low-earth-orbit spacecraft

NASA Astrophysics Data System (ADS)

Beletskiy, A. B.; Mihalev, A. V.; Hahinov, V. V.; Lebedev, V. P.

2016-12-01

This paper presents results of optical observations made during Radar-Progress Experiment performed on April 17, 2013 and July 30, 2014 after approach-correction engines (ACE) of Progress M-17M and Progress M-23M cargo spacecraft in the thermosphere had been started. A region of enhanced emission intensity was recorded during engine operation. This may have been related to the scatter of twilight solar emission along the cargo spacecraft exhaust and to the emergence of additional atomic oxygen [OI] emission at 630 nm. The maximum dimension of the observed emission region was ~330-350 km and ~250-270 km along and across the orbit respectively. For the first time after ACE had been started, an expansion rate of emission region was ~ 7 and ~ 3.5 km/s along and across the orbit respectively. The maximum intensity of the disturbance area for Progress M-17M is estimated as ~40-60 R at 2 nm. Progress M-23M Space Experiment recorded a minor disturbance of atmospheric [OI] 630.0 nm emissions, both in near and in far cargo spacecraft flight paths, which might have been associated with the ACE exhaust gas injection.

Metropolitan all-pass and inter-city quantum communication network.

PubMed

Chen, Teng-Yun; Wang, Jian; Liang, Hao; Liu, Wei-Yue; Liu, Yang; Jiang, Xiao; Wang, Yuan; Wan, Xu; Cai, Wei-Qi; Ju, Lei; Chen, Luo-Kan; Wang, Liu-Jun; Gao, Yuan; Chen, Kai; Peng, Cheng-Zhi; Chen, Zeng-Bing; Pan, Jian-Wei

2010-12-20

We have demonstrated a metropolitan all-pass quantum communication network in field fiber for four nodes. Any two nodes of them can be connected in the network to perform quantum key distribution (QKD). An optical switching module is presented that enables arbitrary 2-connectivity among output ports. Integrated QKD terminals are worked out, which can operate either as a transmitter, a receiver, or even both at the same time. Furthermore, an additional link in another city of 60 km fiber (up to 130 km) is seamless integrated into this network based on a trusted relay architecture. On all the links, we have implemented protocol of decoy state scheme. All of necessary electrical hardware, synchronization, feedback control, network software, execution of QKD protocols are made by tailored designing, which allow a completely automatical and stable running. Our system has been put into operation in Hefei in August 2009, and publicly demonstrated during an evaluation conference on quantum network organized by the Chinese Academy of Sciences on August 29, 2009. Real-time voice telephone with one-time pad encoding between any two of the five nodes (four all-pass nodes plus one additional node through relay) is successfully established in the network within 60 km.

Mixed maximal and explosive strength training in recreational endurance runners.

PubMed

Taipale, Ritva S; Mikkola, Jussi; Salo, Tiina; Hokka, Laura; Vesterinen, Ville; Kraemer, William J; Nummela, Ari; Häkkinen, Keijo

2014-03-01

Supervised periodized mixed maximal and explosive strength training added to endurance training in recreational endurance runners was examined during an 8-week intervention preceded by an 8-week preparatory strength training period. Thirty-four subjects (21-45 years) were divided into experimental groups: men (M, n = 9), women (W, n = 9), and control groups: men (MC, n = 7), women (WC, n = 9). The experimental groups performed mixed maximal and explosive exercises, whereas control subjects performed circuit training with body weight. Endurance training included running at an intensity below lactate threshold. Strength, power, endurance performance characteristics, and hormones were monitored throughout the study. Significance was set at p ≤ 0.05. Increases were observed in both experimental groups that were more systematic than in the control groups in explosive strength (12 and 13% in men and women, respectively), muscle activation, maximal strength (6 and 13%), and peak running speed (14.9 ± 1.2 to 15.6 ± 1.2 and 12.9 ± 0.9 to 13.5 ± 0.8 km Ł h). The control groups showed significant improvements in maximal and explosive strength, but Speak increased only in MC. Submaximal running characteristics (blood lactate and heart rate) improved in all groups. Serum hormones fluctuated significantly in men (testosterone) and in women (thyroid stimulating hormone) but returned to baseline by the end of the study. Mixed strength training combined with endurance training may be more effective than circuit training in recreational endurance runners to benefit overall fitness that may be important for other adaptive processes and larger training loads associated with, e.g., marathon training.

Ingestion of carbohydrate or carbohydrate plus protein does not enhance performance during endurance exercise: a randomized cross-over placebo-controlled clinical trial.

PubMed

Finger, Débora; Lanferdini, Fábio Juner; Farinha, Juliano Boufleur; Brusco, Clarissa Müller; Helal, Lucas; Boeno, Francesco Pinto; Cadore, Eduardo Lusa; Pinto, Ronei Silveira

2018-03-15

Protein (PRO) combined with a carbohydrate (CHO) beverage may have an ergogenic effect on endurance performance. However, evidence regarding its efficacy on similar conditions to athletes' race day is still lacking. To compare the effect of three different nutritional supplementation strategies on performance and muscle recovery in a duathlon protocol. , 13 male athletes (29.7 ± 7.7 years) participated in three simulated Olympic-distance duathlons under three different, randomly assigned, supplementation regimens: carbohydrate drink (CHO, 75 g); isocaloric CHO plus protein drink (CHO+PRO, 60.5 g CHO + 14.5 g PRO); and, placebo drink (PLA), offered during the cycling bout. Blood samples were collected before, immediately after and 24 h after each test for creatine kinase (CK) analysis. Isometric peak torque (PT) was measured before and 24 h after each condition. The primary outcome was the time to complete the last 5km running section (t5km) in a self-selected pace. Statistical differences were considered when p<0.05. There was no difference in t5km between CHO (1270.3 ± 130.5 s) vs. CHO+PRO (1267.2 ± 138.9 s) vs. PLA (1275.4 ± 120 s); p = 0.87; ES ≤ 0.1. Pre-post changes for PT and CK values did not show differences in any of three conditions (p = 0.24, ES ≤ 0.4, p = 0.32, 0.3-1.04). For endurance sports lasting up to 2 h, with a pre-meal containing 1.5 g/kg of CHO, CHO or CHO+PRO supplementation does not offer additional benefits when compared to a PLA in performance and muscle recovery.

Output improvement of Sg. Piah run-off river hydro-electric station with a new computed river flow-based control system

NASA Astrophysics Data System (ADS)

Jidin, Razali; Othman, Bahari

2013-06-01

The lower Sg. Piah hydro-electric station is a river run-off hydro scheme with generators capable of generating 55MW of electricity. It is located 30km away from Sg. Siput, a small town in the state of Perak, Malaysia. The station has two turbines (Pelton) to harness energy from water that flow through a 7km tunnel from a small intake dam. The trait of a run-off river hydro station is small-reservoir that cannot store water for a long duration; therefore potential energy carried by the spillage will be wasted if the dam level is not appropriately regulated. To improve the station annual energy output, a new controller based on the computed river flow has been installed. The controller regulates the dam level with an algorithm based on the river flow derived indirectly from the intake-dam water level and other plant parameters. The controller has been able to maintain the dam at optimum water level and regulate the turbines to maximize the total generation output.

Application of the LEPS technique for Quantitative Precipitation Forecasting (QPF) in Southern Italy: a preliminary study

NASA Astrophysics Data System (ADS)

Federico, S.; Avolio, E.; Bellecci, C.; Colacino, M.; Walko, R. L.

2006-03-01

This paper reports preliminary results for a Limited area model Ensemble Prediction System (LEPS), based on RAMS (Regional Atmospheric Modelling System), for eight case studies of moderate-intense precipitation over Calabria, the southernmost tip of the Italian peninsula. LEPS aims to transfer the benefits of a probabilistic forecast from global to regional scales in countries where local orographic forcing is a key factor to force convection. To accomplish this task and to limit computational time in an operational implementation of LEPS, we perform a cluster analysis of ECMWF-EPS runs. Starting from the 51 members that form the ECMWF-EPS we generate five clusters. For each cluster a representative member is selected and used to provide initial and dynamic boundary conditions to RAMS, whose integrations generate LEPS. RAMS runs have 12-km horizontal resolution. To analyze the impact of enhanced horizontal resolution on quantitative precipitation forecasts, LEPS forecasts are compared to a full Brute Force (BF) ensemble. This ensemble is based on RAMS, has 36 km horizontal resolution and is generated by 51 members, nested in each ECMWF-EPS member. LEPS and BF results are compared subjectively and by objective scores. Subjective analysis is based on precipitation and probability maps of case studies whereas objective analysis is made by deterministic and probabilistic scores. Scores and maps are calculated by comparing ensemble precipitation forecasts against reports from the Calabria regional raingauge network. Results show that LEPS provided better rainfall predictions than BF for all case studies selected. This strongly suggests the importance of the enhanced horizontal resolution, compared to ensemble population, for Calabria for these cases. To further explore the impact of local physiographic features on QPF (Quantitative Precipitation Forecasting), LEPS results are also compared with a 6-km horizontal resolution deterministic forecast. Due to local and mesoscale forcing, the high resolution forecast (Hi-Res) has better performance compared to the ensemble mean for rainfall thresholds larger than 10mm but it tends to overestimate precipitation for lower amounts. This yields larger false alarms that have a detrimental effect on objective scores for lower thresholds. To exploit the advantages of a probabilistic forecast compared to a deterministic one, the relation between the ECMWF-EPS 700 hPa geopotential height spread and LEPS performance is analyzed. Results are promising even if additional studies are required.

Forefoot running improves pain and disability associated with chronic exertional compartment syndrome.

PubMed

Diebal, Angela R; Gregory, Robert; Alitz, Curtis; Gerber, J Parry

2012-05-01

Anterior compartment pressures of the leg as well as kinematic and kinetic measures are significantly influenced by running technique. It is unknown whether adopting a forefoot strike technique will decrease the pain and disability associated with chronic exertional compartment syndrome (CECS) in hindfoot strike runners. For people who have CECS, adopting a forefoot strike running technique will lead to decreased pain and disability associated with this condition. Case series; Level of evidence, 4. Ten patients with CECS indicated for surgical release were prospectively enrolled. Resting and postrunning compartment pressures, kinematic and kinetic measurements, and self-report questionnaires were taken for all patients at baseline and after 6 weeks of a forefoot strike running intervention. Run distance and reported pain levels were recorded. A 15-point global rating of change (GROC) scale was used to measure perceived change after the intervention. After 6 weeks of forefoot run training, mean postrun anterior compartment pressures significantly decreased from 78.4 ± 32.0 mm Hg to 38.4 ± 11.5 mm Hg. Vertical ground-reaction force and impulse values were significantly reduced. Running distance significantly increased from 1.4 ± 0.6 km before intervention to 4.8 ± 0.5 km 6 weeks after intervention, while reported pain while running significantly decreased. The Single Assessment Numeric Evaluation (SANE) significantly increased from 49.9 ± 21.4 to 90.4 ± 10.3, and the Lower Leg Outcome Survey (LLOS) significantly increased from 67.3 ± 13.7 to 91.5 ± 8.5. The GROC scores at 6 weeks after intervention were between 5 and 7 for all patients. One year after the intervention, the SANE and LLOS scores were greater than reported during the 6-week follow-up. Two-mile run times were also significantly faster than preintervention values. No patient required surgery. In 10 consecutive patients with CECS, a 6-week forefoot strike running intervention led to decreased postrunning lower leg intracompartmental pressures. Pain and disability typically associated with CECS were greatly reduced for up to 1 year after intervention. Surgical intervention was avoided for all patients.

Adjustments with running speed reveal neuromuscular adaptations during landing associated with high mileage running training.

PubMed

Verheul, Jasper; Clansey, Adam C; Lake, Mark J

2017-03-01

It remains to be determined whether running training influences the amplitude of lower limb muscle activations before and during the first half of stance and whether such changes are associated with joint stiffness regulation and usage of stored energy from tendons. Therefore, the aim of this study was to investigate neuromuscular and movement adaptations before and during landing in response to running training across a range of speeds. Two groups of high mileage (HM; >45 km/wk, n = 13) and low mileage (LM; <15 km/wk, n = 13) runners ran at four speeds (2.5-5.5 m/s) while lower limb mechanics and electromyography of the thigh muscles were collected. There were few differences in prelanding activation levels, but HM runners displayed lower activations of the rectus femoris, vastus medialis, and semitendinosus muscles postlanding, and these differences increased with running speed. HM runners also demonstrated higher initial knee stiffness during the impact phase compared with LM runners, which was associated with an earlier peak knee flexion velocity, and both were relatively unchanged by running speed. In contrast, LM runners had higher knee stiffness during the slightly later weight acceptance phase and the disparity was amplified with increases in speed. It was concluded that initial knee joint stiffness might predominantly be governed by tendon stiffness rather than muscular activations before landing. Estimated elastic work about the ankle was found to be higher in the HM runners, which might play a role in reducing weight acceptance phase muscle activation levels and improve muscle activation efficiency with running training. NEW & NOTEWORTHY Although neuromuscular factors play a key role during running, the influence of high mileage training on neuromuscular function has been poorly studied, especially in relation to running speed. This study is the first to demonstrate changes in neuromuscular conditioning with high mileage training, mainly characterized by lower thigh muscle activation after touch down, higher initial knee stiffness, and greater estimates of energy return, with adaptations being increasingly evident at faster running speeds. Copyright © 2017 the American Physiological Society.

Performance of collision damage mitigation braking systems and their effects on human injury in the event of car-to-pedestrian accidents.

PubMed

Matsui, Yasuhiro; Han, Yong; Mizuno, Koji

2011-11-01

The number of traffic deaths in Japan was 4,863 in 2010. Pedestrians account for the highest number (1,714, 35%), and vehicle occupants the second highest (1,602, 33%). Pedestrian protection is a key countermeasure to reduce casualties in traffic accidents. A striking vehicle's impact velocity could be considered a parameter influencing the severity of injury and possibility of death in pedestrian crashes. A collision damage mitigation braking system (CDMBS) using a sensor to detect pedestrians could be effective for reducing the vehicle/pedestrian impact velocity. Currently in Japan, cars equipped with the CDMBS also have vision sensors such as a stereo camera for pedestrian detection. However, the ability of vision sensors in production cars to properly detect pedestrians has not yet been established. The effect of reducing impact velocity on the pedestrian injury risk has also not been determined. The first objective of this study is to evaluate the performance of the CDMBS in detecting pedestrians when it is installed in production cars. The second objective of this study is to evaluate the effect of reducing impact velocity on mitigating pedestrian injury. Firstly, impact experiments were performed using a car with the CDMBS in which the car collided with a pedestrian surrogate. In these tests, the velocity was chosen for the various test runs to be 20, 40 and 60 km/h, respectively, which were based on the velocity distribution in real-world pedestrian crashes. The results indicated that the impact velocity reduction ranged approximately from 10 to 15 km/h at the standing location of a pedestrian surrogate at both daytime and nighttime lighting conditions. These results show that the system has the potential to reduce pedestrian casualties from car-to-pedestrian contacts. Secondly, finite-element analyses were performed simulating vehicle-to- pedestrian impacts with the THUMS pedestrian models. The vehicle models selected for the study included a medium sedan, a minicar, and an SUV. Since head and chest injuries are the most typical causes of pedestrian deaths in car-to-pedestrian accidents, the risk of head and chest injuries was calculated when the impact velocity was reduced from 50 km/h to 40 km/h, 30 km/h, and 20 km/h. The results revealed that an impact velocity reduction of 10 km/h mitigated severe pedestrian injury at impact velocities greater than or equal to 40 km/h. Specifically, a significant effect was observed in collisions with the medium sedan and SUV. In Japan, the CDMBS has just started to be installed in medium sedans. The pedestrian injury mitigation will be greatly improved if the system can be applied to various types of vehicles including SUVs in the future.

The Activity Profile of Young Tennis Athletes Playing on Clay and Hard Courts: Preliminary Data

PubMed Central

Adriano Pereira, Lucas; Freitas, Victor; Arruda Moura, Felipe; Saldanha Aoki, Marcelo; Loturco, Irineu

2016-01-01

Abstract The aim of this study was to compare the kinematic characteristics of tennis matches between red clay and hard courts in young tennis players. Eight young tennis players performed two tennis matches on different court surfaces. The match activities were monitored using GPS units. The distance covered in different velocity ranges and the number of accelerations were analyzed. The paired t test and inference based on magnitudes were used to compare the match physical performance between groups. The total distance (24% of difference), high-intensity running distance (15 - 18 km/h) (30% of difference), the number of high-intensity activities (44% of difference), the body load (1% of difference), and accelerations >1.5 g (1.5-2 g and >2 g 7.8 and 8.1 % of difference, respectively) were significantly greater in clay court than hard court matches (p < 0.05). Matches played on the red clay court required players to cover more total and high-intensity running distances and engage in more high-intensity activities than the matches played on the hard court. Finally, on the clay court the body load and the number of accelerations performed (>1.5 g) were possibly higher than on the hard court. PMID:28149359

Respiratory muscle endurance, oxygen saturation index in vastus lateralis and performance during heavy exercise.

PubMed

Oueslati, Ferid; Boone, Jan; Ahmaidi, Said

2016-06-15

The purpose of this study was to investigate the relationships between respiratory muscle endurance, tissue oxygen saturation index dynamics of leg muscle (TSI) and the time to exhaustion (TTE) during high intensity exercise. Eleven males performed a respiratory muscle endurance test, a maximal incremental running field test (8 km h(-1)+0.5 km h(-1) each 60s) and a high-intensity constant speed field test at 90% VO2max. The TSI in vastus lateralis was monitored with near-infrared spectroscopy. The TSI remained steady between 20 and 80% of TTE. Between 80 and 100% of TTE (7.5 ± 6.1%, p<0.05), a significant drop in TSI concomitant with a minute ventilation increase (16 ± 10 l min(-1)) was observed. Moreover, the increase of ventilation was correlated to the drop in TSI (r=0.70, p<0.05). Additionally, respiratory muscle endurance was significantly correlated to TSI time plateau (20-80% TTE) (r=0.83, p<0.05) and to TTE (r=0.95, p<0.001). The results of the present study show that the tissue oxygen saturation plateau might be affected by ventilatory work and that respiratory muscle endurance could be considered as a determinant of performance during heavy exercise. Copyright © 2016 Elsevier B.V. All rights reserved.

Relative spatial soil geochemical variability along two transects across the United States and Canada

USGS Publications Warehouse

Garrett, Robert G.

2009-01-01

The patterns of relative variability differ by transect and horizon. The N–S transect A-horizon soils show significant between-40-km scale variability for 29 elements, with only 4 elements (Ca, Mg, Pb and Sr) showing in excess of 50% of their variability at the within-40-km and ‘at-site’ scales. In contrast, the C-horizon data demonstrate significant between-40-km scale variability for 26 elements, with 21 having in excess of 50% of their variability at the within-40-km and ‘at-site’ scales. In 36 instances, the ‘at-site’ variability is statistically significant in terms of the sample preparation and analysis variability. It is postulated that this contrast between the A- and C- horizons along the N–S transect, that is dominated by agricultural land uses, is due to the local homogenization of Ap-horizon soils by tillage reducing the ‘at-site’ variability. The spatial variability is distributed similarly between scales for the A- and C-horizon soils of the E–W transect. For all elements, there is significant variability at the within-40-km scale. Notwithstanding this, there is significant between-40-km variability for 28 and 20 of the elements in the A- and C-horizon data, respectively. The differences between the two transects are attributed to (1) geology, the N–S transect runs generally parallel to regional strikes, whereas the E–W transect runs across regional structures and lithologies; and (2) land use, with agricultural tillage dominating along the N–S transect. The spatial analysis of the transect data indicates that continental-scale maps demonstrating statistically significant patterns of geochemical variability may be prepared for many elements from data on soil samples collected on a 40 x 40 km grid or similar sampling designs resulting in a sample density of 1 site per 1600 km2.

Wind Prediction Accuracy for Air Traffic Management Decision Support Tools

NASA Technical Reports Server (NTRS)

Cole, Rod; Green, Steve; Jardin, Matt; Schwartz, Barry; Benjamin, Stan

2000-01-01

The performance of Air Traffic Management and flight deck decision support tools depends in large part on the accuracy of the supporting 4D trajectory predictions. This is particularly relevant to conflict prediction and active advisories for the resolution of conflicts and the conformance with of traffic-flow management flow-rate constraints (e.g., arrival metering / required time of arrival). Flight test results have indicated that wind prediction errors may represent the largest source of trajectory prediction error. The tests also discovered relatively large errors (e.g., greater than 20 knots), existing in pockets of space and time critical to ATM DST performance (one or more sectors, greater than 20 minutes), are inadequately represented by the classic RMS aggregate prediction-accuracy studies of the past. To facilitate the identification and reduction of DST-critical wind-prediction errors, NASA has lead a collaborative research and development activity with MIT Lincoln Laboratories and the Forecast Systems Lab of the National Oceanographic and Atmospheric Administration (NOAA). This activity, begun in 1996, has focussed on the development of key metrics for ATM DST performance, assessment of wind-prediction skill for state of the art systems, and development/validation of system enhancements to improve skill. A 13 month study was conducted for the Denver Center airspace in 1997. Two complementary wind-prediction systems were analyzed and compared to the forecast performance of the then standard 60 km Rapid Update Cycle - version 1 (RUC-1). One system, developed by NOAA, was the prototype 40-km RUC-2 that became operational at NCEP in 1999. RUC-2 introduced a faster cycle (1 hr vs. 3 hr) and improved mesoscale physics. The second system, Augmented Winds (AW), is a prototype en route wind application developed by MITLL based on the Integrated Terminal Wind System (ITWS). AW is run at a local facility (Center) level, and updates RUC predictions based on an optimal interpolation of the latest ACARS reports since the RUC run. This paper presents an overview of the study's results including the identification and use of new large mor wind-prediction accuracy metrics that are key to ATM DST performance.

Moisture balance over the Iberian Peninsula computed using a high resolution regional climate model. The impact of 3DVAR data assimilation.

NASA Astrophysics Data System (ADS)

González-Rojí, Santos J.; Sáenz, Jon; Ibarra-Berastegi, Gabriel

2016-04-01

A numerical downscaling exercise over the Iberian Peninsula has been run nesting the WRF model inside ERA Interim. The Iberian Peninsula has been covered by a 15km x 15 km grid with 51 vertical levels. Two model configurations have been tested in two experiments spanning the period 2010-2014 after a one year spin-up (2009). In both cases, the model uses high resolution daily-varying SST fields and the Noah land surface model. In the first experiment (N), after the model is initialised, boundary conditions drive the model, as usual in numerical downscaling experiments. The second experiment (D) is configured the same way as the N case, but 3DVAR data assimilation is run every six hours (00Z, 06Z, 12Z and 18Z) using observations obtained from the PREPBUFR dataset (NCEP ADP Global Upper Air and Surface Weather Observations) using a 120' window around analysis times. For the data assimilation experiment (D), seasonally (monthly) varying background error covariance matrices have been prepared according to the parameterisations used and the mesoscale model domain. For both N and D runs, the moisture balance of the model runs has been evaluated over the Iberian Peninsula, both internally according to the model results (moisture balance in the model) and also in terms of the observed moisture fields from observational datasets (particularly precipitable water and precipitation from observations). Verification has been performed both at the daily and monthly time scales. The verification has also been performed for ERA Interim, the driving coarse-scale dataset used to drive the regional model too. Results show that the leading terms that must be considered over the area are the tendency in the precipitable water column, the divergence of moisture flux, evaporation (computed from latent heat flux at the surface) and precipitation. In the case of ERA Interim, the divergence of Qc is also relevant, although still a minor player in the moisture balance. Both mesoscale model runs are more effective at closing the moisture balance over the whole Iberian Peninsula than ERA Interim. The N experiment (no data assimilation) shows a better closure than the D case, as could be expected from the lack of analysis increments in it. This result is robust both at the daily and monthly time scales. Both ERA Interim and the D experiment produce a negative residual in the balance equation (compatible with excess evaporation or increased convergence of moisture over the Iberian Peninsula). This is a result of the data assimilation process in the D dataset, since in the N experiment the residual is mainly positive. The seasonal cycle of evaporation is much closer in the D experiment to the one in ERA Interim than in the N case, with a higher evaporation during summer months. However, both regional climate model runs show a lower evaporation rate than ERA Interim, particularly during summer months.

Mercury deposition in snow near an industrial emission source in the western U.S. and comparison to ISC3 model predictions

USGS Publications Warehouse

Abbott, M.L.; Susong, D.D.; Krabbenhoft, D.P.; Rood, A.S.

2002-01-01

Mercury (total and methyl) was evaluated in snow samples collected near a major mercury emission source on the Idaho National Engineering and Environmental Laboratory (INEEL) in southeastern Idaho and 160 km downwind in Teton Range in western Wyoming. The sampling was done to assess near-field (<12 km) deposition rates around the source, compare them to those measured in a relatively remote, pristine downwind location, and to use the measurements to develop improved, site-specific model input parameters for precipitation scavenging coefficient and the fraction of Hg emissions deposited locally. Measured snow water concentrations (ng L-1) were converted to deposition (ug m-2) using the sample location snow water equivalent. The deposition was then compared to that predicted using the ISC3 air dispersion/deposition model which was run with a range of particle and vapor scavenging coefficient input values. Accepted model statistical performance measures (fractional bias and normalized mean square error) were calculated for the different modeling runs, and the best model performance was selected. Measured concentrations close to the source (average = 5.3 ng L-1) were about twice those measured in the Teton Range (average = 2.7 ng L-1) which were within the expected range of values for remote background areas. For most of the sampling locations, the ISC3 model predicted within a factor of two of the observed deposition. The best modeling performance was obtained using a scavenging coefficient value for 0.25 ??m diameter particulate and the assumption that all of the mercury is reactive Hg(II) and subject to local deposition. A 0.1 ??m particle assumption provided conservative overprediction of the data, while a vapor assumption resulted in highly variable predictions. Partitioning a fraction of the Hg emissions to elemental Hg(0) (a U.S. EPA default assumption for combustion facility risk assessments) would have underpredicted the observed fallout.

Effects of a Caffeine-Containing Energy Drink on Simulated Soccer Performance

PubMed Central

Del Coso, Juan; Muñoz-Fernández, Víctor E.; Muñoz, Gloria; Fernández-Elías, Valentín E.; Ortega, Juan F.; Hamouti, Nassim; Barbero, José C.; Muñoz-Guerra, Jesús

2012-01-01

Background To investigate the effects of a caffeine-containing energy drink on soccer performance during a simulated game. A second purpose was to assess the post-exercise urine caffeine concentration derived from the energy drink intake. Methodology/Principal Findings Nineteen semiprofessional soccer players ingested 630±52 mL of a commercially available energy drink (sugar-free Red Bull®) to provide 3 mg of caffeine per kg of body mass, or a decaffeinated control drink (0 mg/kg). After sixty minutes they performed a 15-s maximal jump test, a repeated sprint test (7×30 m; 30 s of active recovery) and played a simulated soccer game. Individual running distance and speed during the game were measured using global positioning satellite (GPS) devices. In comparison to the control drink, the ingestion of the energy drink increased mean jump height in the jump test (34.7±4.7 v 35.8±5.5 cm; P<0.05), mean running speed during the sprint test (25.6±2.1 v 26.3±1.8 km · h−1; P<0.05) and total distance covered at a speed higher than 13 km · h−1 during the game (1205±289 v 1436±326 m; P<0.05). In addition, the energy drink increased the number of sprints during the whole game (30±10 v 24±8; P<0.05). Post-exercise urine caffeine concentration was higher after the energy drink than after the control drink (4.1±1.0 v 0.1±0.1 µg · mL−1; P<0.05). Conclusions/significance A caffeine-containing energy drink in a dose equivalent to 3 mg/kg increased the ability to repeatedly sprint and the distance covered at high intensity during a simulated soccer game. In addition, the caffeinated energy drink increased jump height which may represent a meaningful improvement for headers or when players are competing for a ball. PMID:22348079

Effects of a caffeine-containing energy drink on simulated soccer performance.

PubMed

Del Coso, Juan; Muñoz-Fernández, Víctor E; Muñoz, Gloria; Fernández-Elías, Valentín E; Ortega, Juan F; Hamouti, Nassim; Barbero, José C; Muñoz-Guerra, Jesús

2012-01-01

To investigate the effects of a caffeine-containing energy drink on soccer performance during a simulated game. A second purpose was to assess the post-exercise urine caffeine concentration derived from the energy drink intake. Nineteen semiprofessional soccer players ingested 630 ± 52 mL of a commercially available energy drink (sugar-free Red Bull®) to provide 3 mg of caffeine per kg of body mass, or a decaffeinated control drink (0 mg/kg). After sixty minutes they performed a 15-s maximal jump test, a repeated sprint test (7 × 30 m; 30 s of active recovery) and played a simulated soccer game. Individual running distance and speed during the game were measured using global positioning satellite (GPS) devices. In comparison to the control drink, the ingestion of the energy drink increased mean jump height in the jump test (34.7 ± 4.7 v 35.8 ± 5.5 cm; P<0.05), mean running speed during the sprint test (25.6 ± 2.1 v 26.3 ± 1.8 km · h(-1); P<0.05) and total distance covered at a speed higher than 13 km · h(-1) during the game (1205 ± 289 v 1436 ± 326 m; P<0.05). In addition, the energy drink increased the number of sprints during the whole game (30 ± 10 v 24 ± 8; P<0.05). Post-exercise urine caffeine concentration was higher after the energy drink than after the control drink (4.1 ± 1.0 v 0.1 ± 0.1 µg · mL(-1); P<0.05). A caffeine-containing energy drink in a dose equivalent to 3 mg/kg increased the ability to repeatedly sprint and the distance covered at high intensity during a simulated soccer game. In addition, the caffeinated energy drink increased jump height which may represent a meaningful improvement for headers or when players are competing for a ball.

Improved marathon performance by in-race nutritional strategy intervention.

PubMed

Hansen, Ernst Albin; Emanuelsen, Anders; Gertsen, Robert Mørkegaard; Sørensen S, S R

2014-12-01

It was tested whether a marathon was completed faster by applying a scientifically based rather than a freely chosen nutritional strategy. Furthermore, gastrointestinal symptoms were evaluated. Nonelite runners performed a 10 km time trial 7 weeks before Copenhagen Marathon 2013 for estimation of running ability. Based on the time, runners were divided into two similar groups that eventually should perform the marathon by applying the two nutritional strategies. Matched pairs design was applied. Before the marathon, runners were paired based on their prerace running ability. Runners applying the freely chosen nutritional strategy (n = 14; 33.6 ± 9.6 years; 1.83 ± 0.09 m; 77.4 ± 10.6 kg; 45:40 ± 4:32 min for 10 km) could freely choose their in-race intake. Runners applying the scientifically based nutritional strategy (n = 14; 41.9 ± 7.6 years; 1.79 ± 0.11 m; 74.6 ± 14.5 kg; 45:44 ± 4:37 min) were targeting a combined in-race intake of energy gels and water, where the total intake amounted to approximately 0.750 L water, 60 g maltodextrin and glucose, 0.06 g sodium, and 0.09 g caffeine per hr. Gastrointestinal symptoms were assessed by a self-administered postrace questionnaire. Marathon time was 3:49:26 ± 0:25:05 and 3:38:31 ± 0:24:54 hr for runners applying the freely chosen and the scientifically based strategy, respectively (p = .010, effect size=-0.43). Certain runners experienced diverse serious gastrointestinal symptoms, but overall, symptoms were low and not different between groups (p > .05). In conclusion, nonelite runners completed a marathon on average 10:55 min, corresponding to 4.7%, faster by applying a scientifically based rather than a freely chosen nutritional strategy. Furthermore, average values of gastrointestinal symptoms were low and not different between groups.

Continuously on-­going regional climate hindcast simulations for impact applications

NASA Astrophysics Data System (ADS)

Anders, Ivonne; Piringer, Martin; Kaufmann, Hildegard; Knauder, Werner; Resch, Gernot; Andre, Konrad

2017-04-01

Observational data for e.g. temperature, precipitation, radiation, or wind are often used as meteorological forcing for different impact models, like e.g. crop models, urban models, economic models and energy system models. To assess a climate signal, the time period covered by the observation is often too short, they have gaps in between, and are inhomogeneous over time, due to changes in the measurements itself or in the near surrounding. Thus output from global and regional climate models can close the gap and provide homogeneous and physically consistent time series of meteorological parameters. CORDEX evaluation runs performed for the IPCC-AR5 provide a good base for the regional scale. However, with respect to climate services, continuously on-going hindcast simulations are required for regularly updated applications. The Climate Research group at the national Austrian weather service, ZAMG, is focusing on high mountain regions and, especially on the Alps. The hindcast-simulation performed with the regional climate model COSMO-CLM is forced by ERAinterim and optimized for the Alpine Region. The simulation available for the period of 1979-2015 in a spatial resolution of about 10km is prolonged ongoing and fullfils the customer's needs with respect of output variables, levels, intervals and statistical measures. One of the main tasks is to capture strong precipitation events which often occur during summer when low pressure systems develop over the Golf of Genoa, moving to the Northeast. This leads to floods and landslide events in Austria, Czech Republic and Germany. Such events are not sufficiently represented in the CORDEX-evaluation runs. ZAMG use high quality gridded precipitation and temperature data for the Alpine Region (1-6km) to evaluate the model performance. Data is provided e.g. to hydrological modellers (high water, low water), but also to assess icing capability of infrastructure or the calculation the separation distances between livestock farming and residential area.

Enhanced Endurance Performance by Periodization of Carbohydrate Intake: "Sleep Low" Strategy.

PubMed

Marquet, Laurie-Anne; Brisswalter, Jeanick; Louis, Julien; Tiollier, Eve; Burke, Louise M; Hawley, John A; Hausswirth, Christophe

2016-04-01

We investigated the effect of a chronic dietary periodization strategy on endurance performance in trained athletes. Twenty-one triathletes (V˙O2max: 58.7 ± 5.7 mL·min(-1)·kg(-1)) were divided into two groups: a "sleep-low" (SL) (n = 11) and a control (CON) group (n = 10) consumed the same daily carbohydrate (CHO) intake (6 g·kg(-1)·d(-1)) but with different timing over the day to manipulate CHO availability before and after training sessions. The SL strategy consisted of a 3-wk training-diet intervention comprising three blocks of diet-exercise manipulations: 1) "train-high" interval training sessions in the evening with high-CHO availability, 2) overnight CHO restriction ("sleeping-low"), and 3) "train-low" sessions with low endogenous and exogenous CHO availability. The CON group followed the same training program but with high CHO availability throughout training sessions (no CHO restriction overnight, training sessions with exogenous CHO provision). There was a significant improvement in delta efficiency during submaximal cycling for SL versus CON (CON, +1.4% ± 9.3%; SL, +11% ± 15%, P < 0.05). SL also improved supramaximal cycling to exhaustion at 150% of peak aerobic power (CON, +1.63% ± 12.4%; SL, +12.5% ± 19.0%; P = 0.06) and 10-km running performance (CON, -0.10% ± 2.03%; SL, -2.9% ± 2.15%; P < 0.05). Fat mass was decreased in SL (CON, -2.6 ± 7.4; SL, -8.5% ± 7.4% before; P < 0.01), but not lean mass (CON, -0.22 ± 1.0; SL, -0.16% ± 1.7% PRE). Short-term periodization of dietary CHO availability around selected training sessions promoted significant improvements in submaximal cycling economy, as well as supramaximal cycling capacity and 10-km running time in trained endurance athletes.

Mechanical Alterations during 800-m Self-Paced Track Running.

PubMed

Girard, Olivier; Millet, Gregoire P; Micallef, Jean-Paul

2017-04-01

We assessed the time course of running mechanical alterations during an 800-m. On a 200-m indoor track, 18 physical education students performed an 800-m self-paced run. Once per lap, ground reaction forces were measured by a 5-m-long force platform system, and used to determine running kinetics/kinematics and spring-mass characteristics. Compared with 100 m (19.4±1.8 km.h -1 ) running velocity progressively decreased at 300, 500 m but levelled-off at 700 m marks (-5.7±4.6, -10.4±8.3, and -9.1±13.5%, respectively; P<0.001). Stride length (-8.5±2.3%, P<0.01) and frequency (-1.0±1.5%, P=0.05) along with peak braking (-7.5±4.4%, P<0.05) and push-off forces (-5.1±7.2%, P<0.05) decreased from 100 m to 700 m. Peak vertical forces (-3.0±2.7%; P>0.05) and leg compression (+2.8±3.9%; P>0.05) remained unchanged, whereas centre of mass vertical displacement (+24.0±7.0%; P<0.001) increased during the run. Vertical stiffness decreased (-18.1±4.4%; P<0.001), whereas leg stiffness was unchanged (-3.2±4.6%; P>0.05). During an 800 m by physical education students, highest running velocity was achieved early during the run, with a progressive decrease in the second half of the trial. While vertical ground force characteristics remained unchanged, non-specialist runners produced lower peak braking and push-off forces, in turn leading to shorter stride length. Spring-mass model characteristics changed toward lower vertical stiffness values, whereas leg stiffness did not change. © Georg Thieme Verlag KG Stuttgart · New York.

Physiological intensity profile, exercise load and performance predictors of a 65-km mountain ultra-marathon.

PubMed

Fornasiero, Alessandro; Savoldelli, Aldo; Fruet, Damiano; Boccia, Gennaro; Pellegrini, Barbara; Schena, Federico

2018-06-01

The aims of the study were to describe the physiological profile of a 65-km (4000-m cumulative elevation gain) running mountain ultra-marathon (MUM) and to identify predictors of MUM performance. Twenty-three amateur trail-runners performed anthropometric evaluations and an uphill graded exercise test (GXT) for VO 2max, ventilatory thresholds (VTs), power outputs (PMax, PVTs) and heart rate response (HRmax, HR@VTs). Heart rate (HR) was monitored during the race and intensity was expressed as: Zone I (VT2) for exercise load calculation (training impulse, TRIMP). Mean race intensity was 77.1%±4.4% of HRmax distributed as: 85.7%±19.4% Zone I, 13.9%±18.6% Zone II, 0.4%±0.9% Zone III. Exercise load was 766±110 TRIMP units. Race time (11.8±1.6h) was negatively correlated with VO 2max (r = -0.66, P <0.001) and PMax (r = -0.73, P <0.001), resulting these variables determinant in predicting MUM performance, whereas exercise thresholds did not improve performance prediction. Laboratory variables explained only 59% of race time variance, underlining the multi-factorial character of MUM performance. Our results support the idea that VT1 represents a boundary of tolerable intensity in this kind of events, where exercise load is extremely high. This information can be helpful in identifying optimal pacing strategies to complete such extremely demanding MUMs.

Test of High-resolution Global and Regional Climate Model Projections

NASA Astrophysics Data System (ADS)

Stenchikov, Georgiy; Nikulin, Grigory; Hansson, Ulf; Kjellström, Erik; Raj, Jerry; Bangalath, Hamza; Osipov, Sergey

2014-05-01

In scope of CORDEX project we have simulated the past (1975-2005) and future (2006-2050) climates using the GFDL global high-resolution atmospheric model (HIRAM) and the Rossby Center nested regional model RCA4 for the Middle East and North Africa (MENA) region. Both global and nested runs were performed with roughly the same spatial resolution of 25 km in latitude and longitude, and were driven by the 2°x2.5°-resolution fields from GFDL ESM2M IPCC AR5 runs. The global HIRAM simulations could naturally account for interaction of regional processes with the larger-scale circulation features like Indian Summer Monsoon, which is lacking from regional model setup. Therefore in this study we specifically address the consistency of "global" and "regional" downscalings. The performance of RCA4, HIRAM, and ESM2M is tested based on mean, extreme, trends, seasonal and inter-annual variability of surface temperature, precipitation, and winds. The impact of climate change on dust storm activity, extreme precipitation and water resources is specifically addressed. We found that the global and regional climate projections appear to be quite consistent for the modeled period and differ more significantly from ESM2M than between each other.

Medical support during an Ironman 70.3 triathlon race

PubMed Central

Yang, Hae-Rang; Jeong, Jinwoo; Kim, Injoo; Kim, Ji Eun

2017-01-01

Background: The Ironman 70.3 race is also called a half Ironman, and consists of 1.9 km of swimming, 90.1 km of cycling, and 21.1 km of running. The authors provide practical insights that may be useful for medical support in future events by summarizing the process and results of on-scene medical care. Methods: The medical post was established at the transition area between the cycling and running courses, which was close to the finish line, and staffed with the headquarters team comprised of an emergency physician, an EMT, two nurses, and an ambulance with a driver. The other five ambulances were located throughout the course. The medical staff identified participants according to their numbers when providing medical support, and described complaints, treatment provided, and disposition. When treating non-participants, gender and age were recorded instead of numbers. The treatment records were analyzed after the race. Results: The medical team treated a total of 187 participants. One suffered cramps in the calf muscles during the swimming part of the course. Nineteen were treated for injuries suffered during the cycling race. A total of 159 were treated for injuries on the running course. Five casualties, all of which occurred during the cycling race, required transport to hospital. Conclusions: Medical directors preparing medical support during a triathlon event should expect severe injuries in the cycling course. In hot climates, staff may also suffer from heat injuries as well as runners, and proper attention should be paid to these risks. PMID:29026523

Effect of Jump Interval Training on Kinematics of the Lower Limbs and Running Economy.

PubMed

Ache-Dias, Jonathan; Pupo, Juliano Dal; Dellagrana, Rodolfo A; Teixeira, Anderson S; Mochizuki, Luis; Moro, Antônio R P

2018-02-01

Ache-Dias, J, Pupo, JD, Dellagrana, RA, Teixeira, AS, Mochizuki, L, and Moro, ARP. Effect of jump interval training on kinematics of the lower limbs and running economy. J Strength Cond Res 32(2): 416-422, 2017-This study analyzed the effects of the addition of jump interval training (JIT) to continuous endurance training (40-minute running at 70% of peak aerobic velocity, 3 times per week for 4 weeks) on kinematic variables and running economy (RE) during submaximal constant-load running. Eighteen recreational runners, randomized into control group (CG) or experimental group (EG) performed the endurance training. In addition, the EG performed the JIT twice per week, which consisted of 4-6 bouts of continuous vertical jumping (30 seconds) with 5-minute intervals. The oxygen consumption (V[Combining Dot Above]O2) during the submaximal test (performed at 9 km·h) was similar before (EG: 38.48 ± 2.75 ml·kg·min; CG: 36.45 ± 2.70 ml·kg·min) and after training (EG: 37.42 ± 2.54 ml·kg·min; CG: 35.81 ± 3.10 ml·kg·min). No effect of training, group, or interaction (p > 0.05) was found for RE. There was no interaction or group effect for the kinematic variables (p > 0.05). Most of the kinematic variables had a training effect for both groups (support time [p ≤ 0.05]; step rate [SR; p ≤ 0.05]; and step length [SL; p ≤ 0.05]). In addition, according to the practical significance analysis (percentage chances of a better/trivial/worse effect), important effects in leg stiffness (73/25/2), vertical stiffness (73/25/2), SR (71/27/2), and SL (64/33/3) were found for the EG. No significant relationship between RE and stiffness were found for EG and CG. In conclusion, the results suggest that JIT induces important changes in the kinematics of the lower limbs of recreational runners, but the changes do not affect RE.

Semiautomated object-based classification of rain-induced landslides with VHR multispectral images on Madeira Island

NASA Astrophysics Data System (ADS)

Heleno, Sandra; Matias, Magda; Pina, Pedro; Sousa, António Jorge

2016-04-01

A method for semiautomated landslide detection and mapping, with the ability to separate source and run-out areas, is presented in this paper. It combines object-based image analysis and a support vector machine classifier and is tested using a GeoEye-1 multispectral image, sensed 3 days after a major damaging landslide event that occurred on Madeira Island (20 February 2010), and a pre-event lidar digital terrain model. The testing is developed in a 15 km2 wide study area, where 95 % of the number of landslides scars are detected by this supervised approach. The classifier presents a good performance in the delineation of the overall landslide area, with commission errors below 26 % and omission errors below 24 %. In addition, fair results are achieved in the separation of the source from the run-out landslide areas, although in less illuminated slopes this discrimination is less effective than in sunnier, east-facing slopes.

Sensitivity study of heavy precipitation in Limited Area Model climate simulations: influence of the size of the domain and the use of the spectral nudging technique

NASA Astrophysics Data System (ADS)

Colin, Jeanne; Déqué, Michel; Radu, Raluca; Somot, Samuel

2010-10-01

We assess the impact of two sources of uncertainties in a limited area model (LAM) on the representation of intense precipitation: the size of the domain of integration and the use of the spectral nudging technique (driving of the large-scale within the domain of integration). We work in a perfect-model approach where the LAM is driven by a general circulation model (GCM) run at the same resolution and sharing the same physics and dynamics as the LAM. A set of three 50 km resolution simulations run over Western Europe with the LAM ALADIN-Climate and the GCM ARPEGE-Climate are performed to address this issue. Results are consistent with previous studies regarding the seasonal-mean fields. Furthermore, they show that neither the use of the spectral nudging nor the choice of a small domain are detrimental to the modelling of heavy precipitation in the present experiment.

Assimilation of SMOS Soil Moisture Retrievals in the Land Information System

NASA Technical Reports Server (NTRS)

Blankenship, Clay; Case, Jonathan L.; Zavodsky, Brad

2014-01-01

Soil moisture is a crucial variable for weather prediction because of its influence on evaporation. It is of critical importance for drought and flood monitoring and prediction and for public health applications. The NASA Short-term Prediction Research and Transition Center (SPoRT) has implemented a new module in the NASA Land Information System (LIS) to assimilate observations from the ESA's Soil Moisture and Ocean Salinity (SMOS) satellite. SMOS Level 2 retrievals from the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS) instrument are assimilated into the Noah LSM within LIS via an Ensemble Kalman Filter. The retrievals have a target volumetric accuracy of 4% at a resolution of 35-50 km. Parallel runs with and without SMOS assimilation are performed with precipitation forcing from intentionally degraded observations, and then validated against a model run using the best available precipitation data, as well as against selected station observations. The goal is to demonstrate how SMOS data assimilation can improve modeled soil states in the absence of dense rain gauge and radar networks.

Performance of an airborne imaging 92/183 GHz radiometer during the Bering Sea Marginal Ice Zone Experiment (MIZEX-WEST)

NASA Technical Reports Server (NTRS)

Gagliano, J. A.; Mcsheehy, J. J.; Cavalieri, D. J.

1983-01-01

An airborne imaging 92/183 GHz radiometer was recently flown onboard NASA's Convair 990 research aircraft during the February 1983 Bering Sea Marginal Ice Zone Experiment (MIZEX-WEST). The 92 GHz portion of the radiometer was used to gather ice signature data and to generate real-time millimeter wave images of the marginal ice zone. Dry atmospheric conditions in the Arctic resulted in good surface ice signature data for the 183 GHz double sideband (DSB) channel situated + or - 8.75 GHz away from the water vapor absorption line. The radiometer's beam scanner imaged the marginal ice zone over a + or - 45 degrees swath angle about the aircraft nadir position. The aircraft altitude was 30,000 feet (9.20 km) maximum and 3,000 feet (0.92 km) minimum during the various data runs. Calculations of the minimum detectable target (ice) size for the radiometer as a function of aircraft altitude were performed. In addition, the change in the atmospheric attenuation at 92 GHz under varying weather conditions was incorporated into the target size calculations. A radiometric image of surface ice at 92 GHz in the marginal ice zone is included.

Noise Performance of the Advanced LIGO Detectors

NASA Astrophysics Data System (ADS)

Hall, Evan; LIGO Scientific Collaboration

2016-03-01

Advanced LIGO has completed a four-month search for gravitational wave events using two 4-km laser interferometers separated by a 3000 km baseline. These instruments can sense spacetime strain to better than 10-23 /Hz 1 / 2 in their most sensitive frequency band (80 Hz to 400 Hz). The interferometers' sensitivity is limited by a variety of noise sources, including thermal fluctuations of the test masses and their suspensions, quantum and classical fluctuations of the laser light used to interrogate the test masses, residual environmental disturbances, and noises arising from the sensing and control of the interferometers' length and angular degrees of freedom. We present a budget of these noise sources as they appeared during the first observing run, and discuss ongoing improvements as we look forward to Advanced LIGO achieving full design sensitivity. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under cooperative agreement PHY-0757058.

Influence of exercise duration on cardiorespiratory responses, energy cost and tissue oxygenation within a 6 hour treadmill run.

PubMed

Kerhervé, Hugo A; McLean, Scott; Birkenhead, Karen; Parr, David; Solomon, Colin

2017-01-01

The physiological mechanisms for alterations in oxygen utilization ([Formula: see text]) and the energy cost of running ( C r ) during prolonged running are not completely understood, and could be linked with alterations in muscle and cerebral tissue oxygenation. Eight trained ultramarathon runners (three women; mean ± SD; age 37 ± 7 yr; maximum [Formula: see text] 60 ± 15 mL min -1  kg -1 ) completed a 6 hr treadmill run (6TR), which consisted of four modules, including periods of moderate (3 min at 10 km h -1 , 10-CR) and heavy exercise intensities (6 min at 70% of maximum [Formula: see text], HILL), separated by three, 100 min periods of self-paced running (SP). We measured [Formula: see text], minute ventilation ([Formula: see text]), ventilatory efficiency ([Formula: see text]), respiratory exchange ratio (RER), C r , muscle and cerebral tissue saturation index (TSI) during the modules, and heart rate (HR) and perceived exertion (RPE) during the modules and SP. Participants ran 58.3 ± 10.5 km during 6TR. Speed decreased and HR and RPE increased during SP. Across the modules, HR and [Formula: see text] increased (10-CR), and RER decreased (10-CR and HILL). There were no significant changes in [Formula: see text], [Formula: see text], C r , TSI and RPE across the modules. In the context of positive pacing (decreasing speed), increased cardiac drift and perceived exertion over the 6TR, we observed increased RER and increased HR at moderate and heavy exercise intensity, increased [Formula: see text] at moderate intensity, and no effect of exercise duration on ventilatory efficiency, energy cost of running and tissue oxygenation.

Changes in running mechanics and spring-mass behavior induced by a mountain ultra-marathon race.

PubMed

Morin, J B; Tomazin, K; Edouard, P; Millet, G Y

2011-04-07

Changes in running mechanics and spring-mass behavior due to fatigue induced by a mountain ultra-marathon race (MUM, 166km, total positive and negative elevation of 9500m) were studied in 18 ultra-marathon runners. Mechanical measurements were undertaken pre- and 3h post-MUM at 12km h(-1) on a 7m long pressure walkway: contact (t(c)), aerial (t(a)) times, step frequency (f), and running velocity (v) were sampled and averaged over 5-8 steps. From these variables, spring-mass parameters of peak vertical ground reaction force (F(max)), vertical downward displacement of the center of mass (Δz), leg length change (ΔL), vertical (k(vert)) and leg (k(leg)) stiffness were computed. After the MUM, there was a significant increase in f (5.9±5.5%; P<0.001) associated with reduced t(a) (-18.5±17.4%; P<0.001) with no change in t(c), and a significant decrease in both Δz and F(max) (-11.6±10.5 and -6.3±7.3%, respectively; P<0.001). k(vert) increased by 5.6±11.7% (P=0.053), and k(leg) remained unchanged. These results show that 3h post-MUM, subjects ran with a reduced vertical oscillation of their spring-mass system. This is consistent with (i) previous studies concerning muscular structure/function impairment in running and (ii) the hypothesis that these changes in the running pattern could be associated with lower overall impact (especially during the braking phase) supported by the locomotor system at each step, potentially leading to reduced pain during running. Copyright © 2011 Elsevier Ltd. All rights reserved.

Muscle adaptations and performance enhancements of soccer training for untrained men.

PubMed

Krustrup, Peter; Christensen, Jesper F; Randers, Morten B; Pedersen, Henrik; Sundstrup, Emil; Jakobsen, Markus D; Krustrup, Birgitte R; Nielsen, Jens J; Suetta, Charlotte; Nybo, Lars; Bangsbo, Jens

2010-04-01

We examined the physical demands of small-sided soccer games in untrained middle-age males and muscle adaptations and performance effects over 12 weeks of recreational soccer training in comparison with continuous running. Thirty-eight healthy subjects (20-43 years) were randomized into a soccer (SO), running (RU) and control (CO) group. Two-three weekly 1-h training sessions were performed. Muscle lactate (30.1 +/- 4.1 vs. 15.6 +/- 3.3 mmol/kg d.w.), blood lactate, blood glucose and time above 90% HR(max) (20 +/- 4% vs. 1 +/- 1%) were higher (p < 0.05) during training in SO than in RU. After 12 weeks of training, quadriceps muscle mass and mean muscle fibre area were 9 and 15% larger (p < 0.05) in SO, but unaltered in RU, and in SO, the fraction of FTx fibres was lowered (10.7 +/- 1.8 vs. 17.9 +/- 3.2%). In SO, citrate synthase activity was 10 and 14% higher (p < 0.05) after 4 and 12 weeks, but unaltered in RU. After 4 weeks VO(2max) and Yo-Yo IE2 performance were elevated (p < 0.05) to a similar extent in SO (7 and 37%) and RU (6 and 36%) but increased further (p < 0.05) from 4 to 12 weeks in SO (6 and 23%). In SO, 30-m sprint performance was improved (p < 0.05) by 0.11 +/- 0.02 s. Blood lactate during running at 11 km/h was lowered (p < 0.05) from 0 to 4 and 4 to 12 weeks (2.6 +/- 0.3 vs. 3.8 +/- 0.6 vs. 6.1 +/- 0.9 mM) and from 0 to 12 weeks in RU. No changes occurred for CO. In conclusion, recreational soccer organized as small-sided games stimulates both aerobic and anaerobic energy turnover and is an effective type of training leading to significant cardiovascular and muscular adaptations as well as performance enhancements throughout a 12-week training period.

A Fast Multiple-Kernel Method With Applications to Detect Gene-Environment Interaction.

PubMed

Marceau, Rachel; Lu, Wenbin; Holloway, Shannon; Sale, Michèle M; Worrall, Bradford B; Williams, Stephen R; Hsu, Fang-Chi; Tzeng, Jung-Ying

2015-09-01

Kernel machine (KM) models are a powerful tool for exploring associations between sets of genetic variants and complex traits. Although most KM methods use a single kernel function to assess the marginal effect of a variable set, KM analyses involving multiple kernels have become increasingly popular. Multikernel analysis allows researchers to study more complex problems, such as assessing gene-gene or gene-environment interactions, incorporating variance-component based methods for population substructure into rare-variant association testing, and assessing the conditional effects of a variable set adjusting for other variable sets. The KM framework is robust, powerful, and provides efficient dimension reduction for multifactor analyses, but requires the estimation of high dimensional nuisance parameters. Traditional estimation techniques, including regularization and the "expectation-maximization (EM)" algorithm, have a large computational cost and are not scalable to large sample sizes needed for rare variant analysis. Therefore, under the context of gene-environment interaction, we propose a computationally efficient and statistically rigorous "fastKM" algorithm for multikernel analysis that is based on a low-rank approximation to the nuisance effect kernel matrices. Our algorithm is applicable to various trait types (e.g., continuous, binary, and survival traits) and can be implemented using any existing single-kernel analysis software. Through extensive simulation studies, we show that our algorithm has similar performance to an EM-based KM approach for quantitative traits while running much faster. We also apply our method to the Vitamin Intervention for Stroke Prevention (VISP) clinical trial, examining gene-by-vitamin effects on recurrent stroke risk and gene-by-age effects on change in homocysteine level. © 2015 WILEY PERIODICALS, INC.

High-Intensity Cycling Training: The Effect of Work-to-Rest Intervals on Running Performance Measures.

PubMed

Kavaliauskas, Mykolas; Aspe, Rodrigo R; Babraj, John

2015-08-01

The work-to-rest ratio during cycling-based high-intensity interval training (HIT) could be important in regulating physiological and performance adaptations. We sought to determine the effectiveness of cycling-based HIT with different work-to-rest ratios for long-distance running. Thirty-two long-distance runners (age: 39 ± 8 years; sex: 14 men, 18 women; average weekly running training volume: 25 miles) underwent baseline testing (3-km time-trial, V[Combining Dot Above]O2peak and time to exhaustion, and Wingate test) before a 2-week matched-work cycling HIT of 6 × 10-second sprints with different rest periods (30 seconds [R30], 80 seconds [R80], 120 seconds [R120], or control). Three-kilometer time trial was significantly improved in the R30 group only (3.1 ± 4.0%, p = 0.04), whereas time to exhaustion was significantly increased in the 2 groups with a lower work-to-rest ratio (R30 group 6.4 ± 6.3%, p = 0.003 vs. R80 group 4.4 ± 2.7%, p = 0.03 vs. R120 group 1.9 ± 5.0%, p = 0.2). However, improvements in average power production were significantly greater with a higher work-to-rest ratio (R30 group 0.3 ± 4.1%, p = 0.8 vs. R80 group 4.6 ± 4.2%, p = 0.03 vs. R120 group 5.3 ± 5.9%, p = 0.02), whereas peak power significantly increased only in the R80 group (8.5 ± 8.2%, p = 0.04) but not in the R30 group (4.3 ± 6.1%, p = 0.3) or in the R120 group (7.1 ± 7.9%, p = 0.09). Therefore, cycling-based HIT is an effective way to improve running performance, and the type and magnitude of adaptation is dependent on the work-to-rest ratio.

Computation of Solar Radiative Fluxes by 1D and 3D Methods Using Cloudy Atmospheres Inferred from A-train Satellite Data

NASA Technical Reports Server (NTRS)

Barker, Howard W.; Kato, Serji; Wehr, T.

2012-01-01

The main point of this study was to use realistic representations of cloudy atmospheres to assess errors in solar flux estimates associated with 1D radiative transfer models. A scene construction algorithm, developed for the EarthCARE satellite mission, was applied to CloudSat, CALIPSO, and MODIS satellite data thus producing 3D cloudy atmospheres measuring 60 km wide by 13,000 km long at 1 km grid-spacing. Broadband solar fluxes and radiances for each (1 km)2 column where then produced by a Monte Carlo photon transfer model run in both full 3D and independent column approximation mode (i.e., a 1D model).

The Assessment of Microclimate Change due to the Construction of a Small Dam in the Southern Anatolian Irrigation Project Region of Turkey

NASA Astrophysics Data System (ADS)

Tan, Elcin; Onol, Baris; Acar, Merve; Biyik, Gokay; Unal, Yurdanur S.

2013-04-01

The main purpose of this research is to provide information on the change of temperature and humidity fields after the development of a new reservoir in the southeastern part of Turkey. It is believed that pistachio and pomegranates production rate might decrease due to a change of the microclimate of the Southern Anatolian Irrigation Project Region (GAP) with an inclusion of a large water volume. Since temperature and humidity are the significant meteorological variables for growing of these products, their change with the inclusion of the reservoir is analyzed using the WRF model. Two summer years, 2000 and 2002, are studied to indicate the importance of warm and cold summer years, respectively. NCEP/NCAR Reanalysis dataset is used for setting up initial and boundary conditions for 27 km, 9km, 3km, and 1km nested domains. 1 km resolution run is performed using ndown option of the WRF Model for 4 months of these two years, from June to October. 5 different microphysics, atmospheric boundary layer, cumulus, and land use parameterization scheme combinations are analyzed to decide on the appropriate physics scheme combination in order to reduce the biases occurred due to steep topography of this domain of interest. After this decision, the WRF model is performed for both control case, i.e., without the inclusion of any water bodies; and wet case, i.e. with the inclusion of a water body. The preliminary results show that the difference between wet and control cases is about 1°C for 2m temperature; whereas 2m relative humidity change is about 3% from the monthly averages of the 4 months. Therefore, these results may indicate that the production of pistachio and pomegranates may not be affected from the inclusion of a reservoir to the southeastern part of Turkey.

Does haptic steering guidance instigate speeding? A driving simulator study into causes and remedies.

PubMed

Melman, T; de Winter, J C F; Abbink, D A

2017-01-01

An important issue in road traffic safety is that drivers show adverse behavioral adaptation (BA) to driver assistance systems. Haptic steering guidance is an upcoming assistance system which facilitates lane-keeping performance while keeping drivers in the loop, and which may be particularly prone to BA. Thus far, experiments on haptic steering guidance have measured driver performance while the vehicle speed was kept constant. The aim of the present driving simulator study was to examine whether haptic steering guidance causes BA in the form of speeding, and to evaluate two types of haptic steering guidance designed not to suffer from BA. Twenty-four participants drove a 1.8m wide car for 13.9km on a curved road, with cones demarcating a single 2.2m narrow lane. Participants completed four conditions in a counterbalanced design: no guidance (Manual), continuous haptic guidance (Cont), continuous guidance that linearly reduced feedback gains from full guidance at 125km/h towards manual control at 130km/h and above (ContRF), and haptic guidance provided only when the predicted lateral position was outside a lateral bandwidth (Band). Participants were familiarized with each condition prior to the experimental runs and were instructed to drive as they normally would while minimizing the number of cone hits. Compared to Manual, the Cont condition yielded a significantly higher driving speed (on average by 7km/h), whereas ContRF and Band did not. All three guidance conditions yielded better lane-keeping performance than Manual, whereas Cont and ContRF yielded lower self-reported workload than Manual. In conclusion, continuous steering guidance entices drivers to increase their speed, thereby diminishing its potential safety benefits. It is possible to prevent BA while retaining safety benefits by making a design adjustment either in lateral (Band) or in longitudinal (ContRF) direction. Copyright © 2016. Published by Elsevier Ltd.

Relationship between metabolic cost and muscular coactivation across running speeds.

PubMed

Moore, Isabel S; Jones, Andrew M; Dixon, Sharon J

2014-11-01

Muscular coactivation can help stabilise a joint, but contrasting results in previous gait studies highlight that it is not clear whether this is metabolically beneficial. The aim was to assess the relationship between the metabolic cost of running and muscular coactivation across different running speeds, in addition to assessing the reliability and precision of lower limb muscular coactivation. Eleven female recreational runners visited the laboratory on two separate occasions. On both occasions subjects ran at three speeds (9.1, 11 and 12 km h(-1)) for six minutes each. Oxygen consumption and electromyographic data were simultaneously recorded during the final two minutes of each speed. Temporal coactivations of lower limb muscles during the stance phase were calculated. Five muscles were assessed: rectus femoris, vastus lateralis, biceps femoris, tibialis anterior and gastrocnemius lateralis. Nonparametric correlations revealed at least one significant, positive association between lower limb muscular coactivation and the metabolic cost of running for each speed. The length of tibialis anterior activation and muscular coactivation of the biceps femoris-tibialis anterior and gastrocnemius lateralis-tibialis anterior decreased with speed. These results show that longer coactivations of the proximal (rectus femoris-biceps femoris and vastus lateralis-biceps femoris) and leg extensor (rectus femoris-gastrocnemius lateralis) muscles were related to a greater metabolic cost of running, which could be detrimental to performance. The decrease in coactivation in the flexor and distal muscles at faster speeds occurs due to the shorter duration of tibialis anterior activation as speed increases, yet stability may be maintained. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Effect of prior warm-up duration on the time limit at peak speed in untrained men.

PubMed

da Cruz, Victor H; Peserico, Cecília S; Machado, Fabiana A

2017-10-01

The peak speed (Vpeak) and its time limit (tlim) are variables used to prescribe training loads and the intervals durations during interval training, respectively. The aim of this study was to test different warm-up durations (5, 10 and 15 minutes), adapted from the protocol proposed by Billat et al.,1 to determine tlim in untrained men. Fifteen untrained men were submitted to the following laboratory evaluations: 1) an incremental running exercise test on a treadmill starting with a speed of 8 km/h, after a warm-up of walking at 6 km/h for three minutes, and increased by 1 km/h between each successive 3-minute stage until volitional exhaustion to determine Vpeak; 2) three rectangular tests, performed in randomized order, with warm-up durations of 5, 10, and 15 minutes at 60% of Vpeak to determine the tlim5, tlim10, and tlim15; after the warm-up the tests were performed at the speed of the individual Vpeak until volitional exhaustion. It was demonstrated that the duration of the warm-up affected the test duration (tlim). Significant differences were observed between tlim5 and tlim15, and between tlim10 and tlim15. However, tlim15 and tlim10 did not differ. Additionally, duration of the warm-up did not influence other variables (HRmax, RPEmax and post lactate concentrations). Therefore, it was concluded that the duration of the warm-up in tlim tests modifies the test duration in untrained men.

Body Mass and Weekly Training Distance Influence the Pain and Injuries Experienced by Runners Using Minimalist Shoes: A Randomized Controlled Trial.

PubMed

Fuller, Joel T; Thewlis, Dominic; Buckley, Jonathan D; Brown, Nicholas A T; Hamill, Joseph; Tsiros, Margarita D

2017-04-01

Minimalist shoes have been popularized as a safe alternative to conventional running shoes. However, a paucity of research is available investigating the longer-term safety of minimalist shoes. To compare running-related pain and injury between minimalist and conventional shoes in trained runners and to investigate interactions between shoe type, body mass, and weekly training distance. Randomized clinical trial; Level of evidence, 2. Sixty-one trained, habitual rearfoot footfall runners (mean ± SD: body mass, 74.6 ± 9.3 kg; weekly training distance, 25 ± 14 km) were randomly allocated to either minimalist or conventional shoes. Runners gradually increased the time spent running in their allocated shoes over 26 weeks. Running-related pain intensity was measured weekly by use of 100-mm visual analog scales. Time to first running-related injury was also assessed. Interactions were found between shoe type and weekly training distance for weekly running-related pain; greater pain was experienced with minimalist shoes ( P < .05), and clinically meaningful increases (>10 mm) were noted when the weekly training distance was more than 35 km/wk. Eleven of 30 runners sustained an injury in conventional shoes compared with 16 of 31 runners in minimalist shoes (hazard ratio, 1.64; 95% confidence interval, 0.63-4.27; P = .31). A shoe × body mass interaction was found for time to first running-related injury ( P = .01). For runners using minimalist shoes, relative to runners using conventional shoes, the risk of sustaining an injury became more likely with increasing body mass above 71.4 kg, and the risk was moderately increased (hazard ratio, 2.00; 95% confidence interval, 1.10-3.66; P = .02) for runners using minimalist shoes who had a body mass of 85.7 kg. Runners should limit weekly training distance in minimalist shoes to avoid running-related pain. Heavier runners are at greater risk of injury when running in minimalist shoes. Registration: Australian New Zealand Clinical Trials Registry (ACTRN12613000642785).

Impact of Lake Okeechobee Sea Surface Temperatures on Numerical Predictions of Summertime Convective Systems over South Florida

NASA Technical Reports Server (NTRS)

Case, Jonathan L.; Splitt, Michael E.; Fuell, Kevin K.; Santos, Pablo; Lazarus, Steven M.; Jedlovec, Gary J.

2009-01-01

The NASA Short-term Prediction Research and Transition (SPoRT) Center, the Florida Institute of Technology, and the NOAA/NWS Weather Forecast Office at Miami, FL (MFL) are collaborating on a project to investigate the impact of using high-resolution, 2-km Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature (SST) composites within the Weather Research and Forecasting (WRF) prediction system. The NWS MFL is currently running WRF in real-time to support daily forecast operations, using the National Centers for Environmental Prediction Nonhydrostatic Mesoscale Model dynamical core within the NWS Science and Training Resource Center's Environmental Modeling System (EMS) software. Twenty-seven hour forecasts are run daily initialized at 0300, 0900, 1500, and 2100 UTC on a domain with 4-km grid spacing covering the southern half of Florida and adjacent waters of the Gulf of Mexico and Atlantic Ocean. The SSTs are initialized with the NCEP Real-Time Global (RTG) analyses at 1/12deg resolution. The project objective is to determine whether more accurate specification of the lower-boundary forcing over water using the MODIS SST composites within the 4-km WRF runs will result in improved sea fluxes and hence, more accurate e\\olutiono f coastal mesoscale circulations and the associated sensible weather elements. SPoRT conducted parallel WRF EMS runs from February to August 2007 identical to the operational runs at NWS MFL except for the use of MODIS SST composites in place of the RTG product as the initial and boundary conditions over water. During the course of this evaluation, an intriguing case was examined from 6 May 2007, in which lake breezes and convection around Lake Okeechobee evolved quite differently when using the high-resolution SPoRT MODIS SST composites versus the lower-resolution RTG SSTs. This paper will analyze the differences in the 6 May simulations, as well as examine other cases from the summer 2007 in which the WRF-simulated Lake Okeechobee breezes evolved differently due to the SST initialization. The effects on wind fields and precipitation systems will be emphasized, including validation against surface mesonet observations and Stage IV precipitation grids.

Comparisons of Anvil Cirrus Spatial Characteristics between Airborne Observations in DC3 Campaign and WRF Simulations

NASA Astrophysics Data System (ADS)

D'Alessandro, J.; Diao, M.; Chen, M.

2015-12-01

John D'Alessandro1, Minghui Diao1, Ming Chen2, George Bryan2, Hugh Morrison21. Department of Meteorology and Climate Science, San Jose State University2. Mesoscale & Microscale Meteorology Division, National Center for Atmospheric Research, Boulder, CO, 80301 Ice crystal formation requires the prerequisite condition of ice supersaturation, i.e., relative humidity with respect to ice (RHi) greater than 100%. The formation and evolution of ice supersaturated regions (ISSRs) has large impact on the subsequent formation of ice clouds. To examine the characteristics of simulated ice supersaturated regions at various model spatial resolutions, case studies between airborne in-situ measurements in the NSF Deep Convective, Clouds and Chemistry (DC3) campaign (May - June 2012) and WRF simulations are conducted in this work. Recent studies using ~200 m in-situ observations showed that ice supersaturated regions are mostly around 1 km in horizontal scale (Diao et al. 2014). Yet it is still unclear if such observed characteristics can be represented by WRF simulations at various spatial resolutions. In this work, we compare the WRF simulated anvil cirrus spatial characteristics with those observed in the DC3 campaign over the southern great plains in US. The WRF model is run at 1 km and 3 km horizontal grid spacing with a recent update of Thompson microphysics scheme. Our comparisons focus on the spatial characteristics of ISSRs and cirrus clouds, including the distributions of their horizontal scales, the maximum relative humidity with respect to ice (RHi) and the relationship between RHi and temperature. Our previous work on the NCAR CM1 cloud-resolving model shows that the higher resolution runs (i.e., 250m and 1km) generally have better agreement with observations than the coarser resolution (4km) runs. We will examine if similar trend exists for WRF simulations in deep convection cases. In addition, we will compare the simulation results between WRF and CM1, particularly for spatial correlations between ISSRs and cirrus and their evolution (based on the method of Diao et al. 2013). Overall, our work will help to assess the representation of ISSRs and cirrus in WRF simulation based on comparisons with in-situ observations.

Predictor variables for a half marathon race time in recreational male runners

PubMed Central

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Barandun, Ursula; Lepers, Romuald; Rosemann, Thomas

2011-01-01

The aim of this study was to investigate predictor variables of anthropometry, training, and previous experience in order to predict a half marathon race time for future novice recreational male half marathoners. Eighty-four male finishers in the ‘Half Marathon Basel’ completed the race distance within (mean and standard deviation, SD) 103.9 (16.5) min, running at a speed of 12.7 (1.9) km/h. After multivariate analysis of the anthropometric characteristics, body mass index (r = 0.56), suprailiacal (r = 0.36) and medial calf skin fold (r = 0.53) were related to race time. For the variables of training and previous experience, speed in running of the training sessions (r = −0.54) were associated with race time. After multivariate analysis of both the significant anthropometric and training variables, body mass index (P = 0.0150) and speed in running during training (P = 0.0045) were related to race time. Race time in a half marathon might be partially predicted by the following equation (r2 = 0.44): Race time (min) = 72.91 + 3.045 * (body mass index, kg/m2) −3.884 * (speed in running during training, km/h) for recreational male runners. To conclude, variables of both anthropometry and training were related to half marathon race time in recreational male half marathoners and cannot be reduced to one single predictor variable. PMID:24198577

Predictor variables for a half marathon race time in recreational male runners.

PubMed

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Barandun, Ursula; Lepers, Romuald; Rosemann, Thomas

2011-01-01

The aim of this study was to investigate predictor variables of anthropometry, training, and previous experience in order to predict a half marathon race time for future novice recreational male half marathoners. Eighty-four male finishers in the 'Half Marathon Basel' completed the race distance within (mean and standard deviation, SD) 103.9 (16.5) min, running at a speed of 12.7 (1.9) km/h. After multivariate analysis of the anthropometric characteristics, body mass index (r = 0.56), suprailiacal (r = 0.36) and medial calf skin fold (r = 0.53) were related to race time. For the variables of training and previous experience, speed in running of the training sessions (r = -0.54) were associated with race time. After multivariate analysis of both the significant anthropometric and training variables, body mass index (P = 0.0150) and speed in running during training (P = 0.0045) were related to race time. Race time in a half marathon might be partially predicted by the following equation (r(2) = 0.44): Race time (min) = 72.91 + 3.045 * (body mass index, kg/m(2)) -3.884 * (speed in running during training, km/h) for recreational male runners. To conclude, variables of both anthropometry and training were related to half marathon race time in recreational male half marathoners and cannot be reduced to one single predictor variable.

Criterion-Validity of Commercially Available Physical Activity Tracker to Estimate Step Count, Covered Distance and Energy Expenditure during Sports Conditions

PubMed Central

Wahl, Yvonne; Düking, Peter; Droszez, Anna; Wahl, Patrick; Mester, Joachim

2017-01-01

Background: In the past years, there was an increasing development of physical activity tracker (Wearables). For recreational people, testing of these devices under walking or light jogging conditions might be sufficient. For (elite) athletes, however, scientific trustworthiness needs to be given for a broad spectrum of velocities or even fast changes in velocities reflecting the demands of the sport. Therefore, the aim was to evaluate the validity of eleven Wearables for monitoring step count, covered distance and energy expenditure (EE) under laboratory conditions with different constant and varying velocities. Methods: Twenty healthy sport students (10 men, 10 women) performed a running protocol consisting of four 5 min stages of different constant velocities (4.3; 7.2; 10.1; 13.0 km·h−1), a 5 min period of intermittent velocity, and a 2.4 km outdoor run (10.1 km·h−1) while wearing eleven different Wearables (Bodymedia Sensewear, Beurer AS 80, Polar Loop, Garmin Vivofit, Garmin Vivosmart, Garmin Vivoactive, Garmin Forerunner 920XT, Fitbit Charge, Fitbit Charge HR, Xaomi MiBand, Withings Pulse Ox). Step count, covered distance, and EE were evaluated by comparing each Wearable with a criterion method (Optogait system and manual counting for step count, treadmill for covered distance and indirect calorimetry for EE). Results: All Wearables, except Bodymedia Sensewear, Polar Loop, and Beurer AS80, revealed good validity (small MAPE, good ICC) for all constant and varying velocities for monitoring step count. For covered distance, all Wearables showed a very low ICC (<0.1) and high MAPE (up to 50%), revealing no good validity. The measurement of EE was acceptable for the Garmin, Fitbit and Withings Wearables (small to moderate MAPE), while Bodymedia Sensewear, Polar Loop, and Beurer AS80 showed a high MAPE up to 56% for all test conditions. Conclusion: In our study, most Wearables provide an acceptable level of validity for step counts at different constant and intermittent running velocities reflecting sports conditions. However, the covered distance, as well as the EE could not be assessed validly with the investigated Wearables. Consequently, covered distance and EE should not be monitored with the presented Wearables, in sport specific conditions. PMID:29018355

On-board measurement of particle numbers and their size distribution from a light-duty diesel vehicle: Influences of VSP and altitude.

PubMed

Liu, Jia; Ge, Yunshan; Wang, Xin; Hao, Lijun; Tan, Jianwei; Peng, Zihang; Zhang, Chuanzhen; Gong, Huiming; Huang, Ying

2017-07-01

In this study, the particle size-resolved distribution from a China-3 certificated light-duty diesel vehicle was measured by using a portable emission measurement system (PEMS). In order to examine the influences of vehicle specific power (VSP) and high-altitude operation, measurements were conducted at 8 constant speeds, which ranged from 10 to 80km/hr at 10km/hr intervals, and two different high altitudes, namely 2200 and 3200m. The results demonstrated that the numbers of particles in all size ranges decreased significantly as VSP increased when the test vehicle was running at lower speeds (<20km/hr), while at a moderate speed (between 30 and 60km/hr), the particle number was statistically insensitive to increase VSP. Under high-speed cruising conditions, the numbers of ultrafine particles and PM 2.5 were insensitive to changes in VSP, but the numbers of nanoparticles and PM 10 surged considerably. An increase in the operational altitude of the test vehicle resulted in increased particle number emissions at low and high driving speeds; however, particle numbers obtained at moderate speeds decreased as altitude rose. When the test vehicle was running at moderate speeds, particle numbers measured at the two altitudes were very close, except for comparatively higher number concentrations of nanoparticles measured at 2200m. Copyright © 2017. Published by Elsevier B.V.

Performance study of the wearable one-lead wireless electrocardiographic monitoring system.

PubMed

Hong, Sungyoup; Yang, Yougmo; Kim, Seunghwan; Shin, Seungcheol; Lee, Inbum; Jang, Yongwon; Kim, Kiseong; Yi, Hwayeon

2009-03-01

This study attempts to compare and assess the performance of a wearable electrocardiogram (ECG) using a sensing fabric electrode and a Bluetooth network with a conventional ECG. A one-lead ECG examination was performed using Bioshirt and an iWorx 214 while walking or running at 3, 6, and 9 km per hour. A correlation coefficient of a heart rate variability (HRV) between these two devices was higher than 0.96 and power spectral density of HRV measured also showed an excellent agreement. Thus, both of these two ECG devices showed similar detection capability for R peaks. The measured values for wave duration and intervals of both devices concur with each other. The intensity of noise is controversial. The ECG device using a sensing fabric electrode and a wireless network showed an ECG signal detection and transmission capability similar to that of a conventional ECG device.

Meteorological and operational aspects of 46 clear air turbulence sampling missions with an instrument B-57B aircraft. Volume 1: Program summary

NASA Technical Reports Server (NTRS)

Davis, R. E.; Champine, R. A.; Ehernberger, L. J.

1979-01-01

The results of 46 clear air turbulence (CAT) probing missions conducted with an extensively instrumented B-57B aircraft are summarized. Turbulence samples were obtained under diverse conditions including mountain waves, jet streams, upper level fronts and troughs, and low altitude mechanical and thermal turbulence. CAT was encouraged on 20 flights comprising 77 data runs. In all, approximately 4335 km were flown in light turbulence, 1415 km in moderate turbulence, and 255 km in severe turbulence during the program. The flight planning, operations, and turbulence forecasting aspects conducted with the B-57B aircraft are presented.

The Met Office Coupled Atmosphere/Land/Ocean/Sea-Ice Data Assimilation System

NASA Astrophysics Data System (ADS)

Lea, Daniel; Mirouze, Isabelle; Martin, Matthew; Hines, Adrian; Guiavarch, Catherine; Shelly, Ann

2014-05-01

The Met Office has developed a weakly-coupled data assimilation (DA) system using the global coupled model HADGEM3 (Hadley Centre Global Environment Model, version 3). This model combines the atmospheric model UM (Unified Model) at 60 km horizontal resolution on 85 vertical levels, the ocean model NEMO (Nucleus for European Modeling of the Ocean) at 25 km (at the equator) horizontal resolution on 75 vertical levels, and the sea-ice model CICE at the same resolution as NEMO. The atmosphere and the ocean/sea-ice fields are coupled every 1-hour using the OASIS coupler. The coupled model is corrected using two separate 6-hour window data assimilation systems: a 4D-Var for the atmosphere with associated soil moisture content nudging and snow analysis schemes on the one hand, and a 3D-Var FGAT for the ocean and sea-ice on the other hand. The background information in the DA systems comes from a previous 6-hour forecast of the coupled model. To show the impact of coupled DA, one-month experiments have been carried out, including 1) a full atmosphere/land/ocean/sea-ice coupled DA run, 2) an atmosphere-only run forced by OSTIA SSTs and sea-ice with atmosphere and land DA, and 3) an ocean-only run forced by atmospheric fields from run 2 with ocean and sea-ice DA. In addition, 5-day forecast runs, started twice a day, have been produced from initial conditions generated by either run 1 or a combination of runs 2 and 3. The different results have been compared to each other and, whenever possible, to other references such as the Met Office atmosphere and ocean operational analyses or the OSTIA data. These all show the coupled DA system functioning well. Evidence of imbalances and initialisation shocks has also been looked for.

Energy cost and lower leg muscle activities during erect bipedal locomotion under hyperoxia.

PubMed

Abe, Daijiro; Fukuoka, Yoshiyuki; Maeda, Takafumi; Horiuchi, Masahiro

2018-06-19

Energy cost of transport per unit distance (CoT) against speed shows U-shaped fashion in walking and linear fashion in running, indicating that there exists a specific walking speed minimizing the CoT, being defined as economical speed (ES). Another specific gait speed is the intersection speed between both fashions, being called energetically optimal transition speed (EOTS). We measured the ES, EOTS, and muscle activities during walking and running at the EOTS under hyperoxia (40% fraction of inspired oxygen) on the level and uphill gradients (+ 5%). Oxygen consumption [Formula: see text] and carbon dioxide output [Formula: see text] were measured to calculate the CoT values at eight walking speeds (2.4-7.3 km h -1 ) and four running speeds (7.3-9.4 km h - 1 ) in 17 young males. Electromyography was recorded from gastrocnemius medialis, gastrocnemius lateralis (GL), and tibialis anterior (TA) to evaluate muscle activities. Mean power frequency (MPF) was obtained to compare motor unit recruitment patterns between walking and running. [Formula: see text], [Formula: see text], and CoT values were lower under hyperoxia than normoxia at faster walking speeds and any running speeds. A faster ES on the uphill gradient and slower EOTS on both gradients were observed under hyperoxia than normoxia. GL and TA activities became lower when switching from walking to running at the EOTS under both FiO 2 conditions on both gradients, so did the MPF in the TA. ES and EOTS were influenced by reduced metabolic demands induced by hyperoxia. GL and TA activities in association with a lower shift of motor unit recruitment patterns in the TA would be related to the gait selection when walking or running at the EOTS. UMIN000017690 ( R000020501 ). Registered May 26, 2015, before the first trial.

Body Weight, Serum Sodium Levels, and Renal Function in an Ultra-Distance Mountain Run.

PubMed

Scotney, Bianca; Reid, Steve

2015-07-01

To determine body weight and serum [Na] changes in runners completing an 85-km mountain run, particularly with reference to their "in-race" hydration protocols. Prospective observational cohort study. Cradle Mountain Run, Tasmania, Australia, February 2011. Forty-four runners (86% of starters) prospectively enrolled, with 41 runners (80% of starters) eligible for inclusion in final data set. Body weight change, serum sodium concentration change, and hydration plan (according to thirst vs preplanned fluid consumption). There was 1 case of exercise-associated hyponatremia (EAH) [postrace [Na], 132 mmol/L]. This runner was asymptomatic. There was a strongly significant correlation between the change in serum [Na] and body weight change during the race. There was a significant inverse correlation between serum [Na] and volume of fluid consumed. Change of serum [Na] was not correlated with the proportion of water versus electrolyte drink consumed. Runners drinking to thirst consumed significantly lower average fluid volumes and had higher postrace serum [Na] than those complying with a preplanned hydration protocol (142 mmol/L vs 139 mmol/L). More experienced runners tended to drink to thirst. There was a 2% incidence of EAH in this study. Serum [Na] change during an 85-km mountain run was inversely correlated with the volume of fluid consumed. The results provide further evidence that EAH is a dilutional hyponatremia caused by excessive consumption of hypotonic fluids. Drinking to thirst represents a safe hydration strategy for runners in a wilderness environment. Drinking to thirst during endurance running events should be promoted as a safe hydration practice.

Energy requirements of tire pulling.

PubMed

Fredriksen, Per M; Mamen, Asgeir

2017-10-01

We have investigated the effect using walking poles and pulling tires at 4 and 6 km·h-1 (1.11 and 1.67 m·s-1) speeds on oxygen uptake (V̇O2) and heart rate. Eleven subjects, 6 males, with a mean (SD) age of 25.2 (6.9) years participated in field tests involving walking without poles, walking with poles and tire pulling with poles. Increasing the load caused the largest increases in energy demand, more than 4 MET. Speed increase also caused substantial energy increase, approximately 4 MET. Increasing the inclination only modestly increased the oxygen uptake, approximately 2 MET. In both level walking and uphill walking, using poles marginally increased oxygen uptake compared to working without poles. Pulling one tire (12.5 kg) required an oxygen uptake of 27 (4) mL·kg-1·min-1 at 4 km·h-1 and 0% inclination. Adding one more tire (6 kg) drove the oxygen uptake further up to 39 (4) mL·kg-1·min-1. This is close to the requirement of level running at 10.5 km·h-1. Pulling both tires at 6 km·h-1 and 5% inclination required a V̇O2 of 54 (6) mL·kg-1·min-1, equal to running uphill at 5% inclination and 12.5 km·h-1 speed. Heart rate rose comparably with oxygen uptake. At 4 km·h-1 and 0% inclination the increase was 29 bpm, from 134 (21) to 163 (22) bpm when going from pulling one tire to two tires. In the hardest exercise, 6 km·h-1 and 5% inclination, heart rate reached 174 (14) bpm. The study showed that tire pulling even at slow speeds has an energy requirement that is so large that the activity may be feasible as endurance training.

Grid-based Meteorological and Crisis Applications

NASA Astrophysics Data System (ADS)

Hluchy, Ladislav; Bartok, Juraj; Tran, Viet; Lucny, Andrej; Gazak, Martin

2010-05-01

We present several applications from domain of meteorology and crisis management we developed and/or plan to develop. Particularly, we present IMS Model Suite - a complex software system designed to address the needs of accurate forecast of weather and hazardous weather phenomena, environmental pollution assessment, prediction of consequences of nuclear accident and radiological emergency. We discuss requirements on computational means and our experiences how to meet them by grid computing. The process of a pollution assessment and prediction of the consequences in case of radiological emergence results in complex data-flows and work-flows among databases, models and simulation tools (geographical databases, meteorological and dispersion models, etc.). A pollution assessment and prediction requires running of 3D meteorological model (4 nests with resolution from 50 km to 1.8 km centered on nuclear power plant site, 38 vertical levels) as well as running of the dispersion model performing the simulation of the release transport and deposition of the pollutant with respect to the numeric weather prediction data, released material description, topography, land use description and user defined simulation scenario. Several post-processing options can be selected according to particular situation (e.g. doses calculation). Another example is a forecasting of fog as one of the meteorological phenomena hazardous to the aviation as well as road traffic. It requires complicated physical model and high resolution meteorological modeling due to its dependence on local conditions (precise topography, shorelines and land use classes). An installed fog modeling system requires a 4 time nested parallelized 3D meteorological model with 1.8 km horizontal resolution and 42 levels vertically (approx. 1 million points in 3D space) to be run four times daily. The 3D model outputs and multitude of local measurements are utilized by SPMD-parallelized 1D fog model run every hour. The fog forecast model is a subject of the parameterization and parameter optimization before its real deployment. The parameter optimization requires tens of evaluations of the parameterized model accuracy and each evaluation of the model parameters requires re-running of the hundreds of meteorological situations collected over the years and comparison of the model output with the observed data. The architecture and inherent heterogeneity of both examples and their computational complexity and their interfaces to other systems and services make them well suited for decomposition into a set of web and grid services. Such decomposition has been performed within several projects we participated or participate in cooperation with academic sphere, namely int.eu.grid (dispersion model deployed as a pilot application to an interactive grid), SEMCO-WS (semantic composition of the web and grid services), DMM (development of a significant meteorological phenomena prediction system based on the data mining), VEGA 2009-2011 and EGEE III. We present useful and practical applications of technologies of high performance computing. The use of grid technology provides access to much higher computation power not only for modeling and simulation, but also for the model parameterization and validation. This results in the model parameters optimization and more accurate simulation outputs. Having taken into account that the simulations are used for the aviation, road traffic and crisis management, even small improvement in accuracy of predictions may result in significant improvement of safety as well as cost reduction. We found grid computing useful for our applications. We are satisfied with this technology and our experience encourages us to extend its use. Within an ongoing project (DMM) we plan to include processing of satellite images which extends our requirement on computation very rapidly. We believe that thanks to grid computing we are able to handle the job almost in real time.

Crustal Fractures of Ophir Planum

NASA Image and Video Library

2002-05-23

This NASA Mars Odyssey image covers a tract of plateau territory called Ophir Planum. The most obvious features in this scene are the fractures ranging from 1 to 5 km wide running from the upper left to lower right.

Turbidity Currents With Equilibrium Basal Driving Layers: A Mechanism for Long Runout

NASA Astrophysics Data System (ADS)

Luchi, R.; Balachandar, S.; Seminara, G.; Parker, G.

2018-02-01

Turbidity currents run out over 100 km in lakes and reservoirs, and over 1,000 km in the ocean. They do so without dissipating themselves via excess entrainment of ambient water. Existing layer-averaged formulations cannot capture this. We use a numerical model to describe the temporal evolution of a turbidity current toward steady state under condition of zero net sediment flux at the bed. The flow self-partitions itself into two layers. The lower "driving layer" approaches an invariant flow thickness, velocity profile, and suspended sediment concentration profile that sequesters nearly all of the suspended sediment. This layer can continue indefinitely at steady state over a constant bed slope. The upper "driven layer" contains a small fraction of the suspended sediment. The devolution of the flow into these two layers likely allows the driving layer to run out long distances.

Dose response for selected environmental air pollutants: A study on runners: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silverman, F.

This study examined the effects of air pollution on runners during outdoor training runs in downtown Toronto from 1985-88. Subjects were selected from the Longboat Roadrunners Club, a local competitive group which carries out weekly training runs of 10-16 km in downtown Toronto and along the Lakeshore transportation corridor during rush hour. Pulmonary function and an oxygen rebreathing estimate of blood carboxyhaemoglobin level were obtained before and after 75 training runs involving 70 athletes. Subjective reports of symptoms and a personal estimate of exposure to air pollution over the run were noted. Local pollutant concentrations including carbon monoxide, nitrogen dioxide,more » sulfur dioxide and respirable suspended particulate matter, along with dry bulb temperature and relative humidity, were measured using portable multipollutant samplers.« less

The 2006 July 17 Java (Indonesia) tsunami from satellite imagery and numerical modelling: a single or complex source?

NASA Astrophysics Data System (ADS)

Hébert, H.; Burg, P.-E.; Binet, R.; Lavigne, F.; Allgeyer, S.; Schindelé, F.

2012-12-01

The Mw 7.8 2006 July 17 earthquake off the southern coast of Java, Indonesia, has been responsible for a very large tsunami causing more than 700 casualties. The tsunami has been observed on at least 200 km of coastline in the region of Pangandaran (West Java), with run-up heights from 5 to more than 20 m. Such a large tsunami, with respect to the source magnitude, has been attributed to the slow character of the seismic rupture, defining the event as a so-called tsunami earthquake, but it has also been suggested that the largest run-up heights are actually the result of a second local landslide source. Here we test whether a single slow earthquake source can explain the tsunami run-up, using a combination of new detailed data in the region of the largest run-ups and comparison with modelled run-ups for a range of plausible earthquake source models. Using high-resolution satellite imagery (SPOT 5 and Quickbird), the coastal impact of the tsunami is refined in the surroundings of the high-security Permisan prison on Nusa Kambangan island, where 20 m run-up had been recorded directly after the event. These data confirm the extreme inundation lengths close to the prison, and extend the area of maximum impact further along the Nusa Kambangan island (about 20 km of shoreline), where inundation lengths reach several hundreds of metres, suggesting run-up as high as 10-15 m. Tsunami modelling has been conducted in detail for the high run-up Permisan area (Nusa Kambangan) and the PLTU power plant about 25 km eastwards, where run-up reached only 4-6 m and a video recording of the tsunami arrival is available. For the Permisan prison a high-resolution DEM was built from stereoscopic satellite imagery. The regular basin of the PLTU plant was designed using photographs and direct observations. For the earthquake's mechanism, both static (infinite) and finite (kinematic) ruptures are investigated using two published source models. The models account rather well for the sea level variation at PLTU, showing a better agreement in arrival times with the finite rupture, and predict the Permisan area to be one of the regions where tsunami waves would have focussed. However, the earthquake models that match the data at PTLU do not predict that the wave heights at Permisan are an overall maximum, and do not predict there more than 10 m of the 21 observed. Hence, our results confirm that an additional localized tsunami source off Nusa Kambangan island, such as a submarine landslide, may have increased the tsunami impact for the Permisan site. This reinforces the importance for hazard assessment of further mapping and understanding local potential for submarine sliding, as a tsunami source added to usual earthquake sources.

Does player unavailability affect football teams' match physical outputs? A two-season study of the UEFA champions league.

PubMed

Windt, Johann; Ekstrand, Jan; Khan, Karim M; McCall, Alan; Zumbo, Bruno D

2018-05-01

Player unavailability negatively affects team performance in elite football. However, whether player unavailability and its concomitant performance decrement is mediated by any changes in teams' match physical outputs is unknown. We examined whether the number of players injured (i.e. unavailable for match selection) was associated with any changes in teams' physical outputs. Prospective cohort study. Between-team variation was calculated by correlating average team availability with average physical outputs. Within-team variation was quantified using linear mixed modelling, using physical outputs - total distance, sprint count (efforts over 20km/h), and percent of distance covered at high speeds (>14km/h) - as outcome variables, and player unavailability as the independent variable of interest. To control for other factors that may influence match physical outputs, stage (group stage/knockout), venue (home/away), score differential, ball possession (%), team ranking (UEFA Club Coefficient), and average team age were all included as covariates. Teams' average player unavailability was positively associated with the average number of sprints they performed in matches across two seasons. Multilevel models similarly demonstrated that having 4 unavailable players was associated with 20.8 more sprints during matches in 2015/2016, and with an estimated 0.60-0.77% increase in the proportion of total distance run above 14km/h in both seasons. Player unavailability had a possibly positive and likely positive association with total match distances in the two respective seasons. Having more players injured and unavailable for match selection was associated with an increase in teams' match physical outputs. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

High resolution modelling of wind fields for optimization of empirical storm flood predictions

NASA Astrophysics Data System (ADS)

Brecht, B.; Frank, H.

2014-05-01

High resolution wind fields are necessary to predict the occurrence of storm flood events and their magnitude. Deutscher Wetterdienst (DWD) created a catalogue of detailed wind fields of 39 historical storms at the German North Sea coast from the years 1962 to 2011. The catalogue is used by the Niedersächsisches Landesamt für Wasser-, Küsten- und Naturschutz (NLWKN) coastal research center to improve their flood alert service. The computation of wind fields and other meteorological parameters is based on the model chain of the DWD going from the global model GME via the limited-area model COSMO with 7 km mesh size down to a COSMO model with 2.2 km. To obtain an improved analysis COSMO runs are nudged against observations for the historical storms. The global model GME is initialised from the ERA reanalysis data of the European Centre for Medium-Range Weather Forecasts (ECMWF). As expected, we got better congruency with observations of the model for the nudging runs than the normal forecast runs for most storms. We also found during the verification process that different land use data sets could influence the results considerably.

Meta-Analyses of the Effects of Habitual Running on Indices of Health in Physically Inactive Adults.

PubMed

Hespanhol Junior, Luiz Carlos; Pillay, Julian David; van Mechelen, Willem; Verhagen, Evert

2015-10-01

In order to implement running to promote physical activity, it is essential to quantify the extent to which running improves health. The aim was to summarise the literature on the effects of endurance running on biomedical indices of health in physically inactive adults. Electronic searches were conducted in October 2014 on PubMed, Embase, CINAHL, SPORTDiscus, PEDro, the Cochrane Library and LILACS, with no limits of date and language of publication. Randomised controlled trials (with a minimum of 8 weeks of running training) that included physically inactive but healthy adults (18-65 years) were selected. The studies needed to compare intervention (i.e. endurance running) and control (i.e., no intervention) groups. Two authors evaluated study eligibility, extracted data, and assessed risk of bias; a third author resolved any uncertainties. Random-effects meta-analyses were performed to summarise the estimates for length of training and sex. A dose-response analysis was performed with random-effects meta-regression in order to investigate the relationship between running characteristics and effect sizes. After screening 22,380 records, 49 articles were included, of which 35 were used to combine data on ten biomedical indices of health. On average the running programs were composed of 3.7 ± 0.9 sessions/week, 2.3 ± 1.0 h/week, 14.4 ± 5.4 km/week, at 60-90% of the maximum heart rate, and lasted 21.5 ± 16.8 weeks. After 1 year of training, running was effective in reducing body mass by 3.3 kg [95% confidence interval (CI) 4.1-2.5], body fat by 2.7% (95% CI 5.1-0.2), resting heart rate by 6.7 min(-1) (95% CI 10.3-3.0) and triglycerides by 16.9 mg dl(-1) (95% CI 28.1-5.6). Also, running significantly increased maximal oxygen uptake (VO2max) by 7.1 ml min(-1) kg(-1) (95% CI 5.0-9.1) and high-density lipoprotein (HDL) cholesterol by 3.3 mg dl(-1) (95% CI 1.2-5.4). No significant effect was found for lean body mass, body mass index, total cholesterol and low-density lipoprotein cholesterol after 1 year of training. In the dose-response analysis, larger effect sizes were found for longer length of training. It was only possible to combine the data of ten out the 161 outcome measures identified. Lack of information on training characteristics precluded a multivariate model in the dose-response analysis. Endurance running was effective in providing substantial beneficial effects on body mass, body fat, resting heart rate, VO2max, triglycerides and HDL cholesterol in physically inactive adults. The longer the length of training, the larger the achieved health benefits. Clinicians and health authorities can use this information to advise individuals to run, and to support policies towards investing in running programs.

Participation and Performance Trends in Triple Iron Ultra-triathlon – a Cross-sectional and Longitudinal Data Analysis

PubMed Central

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Lepers, Romuald

2012-01-01

Purpose The aims of the present study were to investigate (i) the changes in participation and performance and (ii) the gender difference in Triple Iron ultra-triathlon (11.4 km swimming, 540 km cycling and 126.6 km running) across years from 1988 to 2011. Methods For the cross-sectional data analysis, the association between with overall race times and split times was investigated using simple linear regression analyses and analysis of variance. For the longitudinal data analysis, the changes in race times for the five men and women with the highest number of participations were analysed using simple linear regression analyses. Results During the studied period, the number of finishers were 824 (71.4%) for men and 80 (78.4%) for women. Participation increased for men (r 2=0.27, P<0.01) while it remained stable for women (8%). Total race times were 2,146 ± 127.3 min for men and 2,615 ± 327.2 min for women (P<0.001). Total race time decreased for men (r 2=0.17; P=0.043), while it increased for women (r 2=0.49; P=0.001) across years. The gender difference in overall race time for winners increased from 10% in 1992 to 42% in 2011 (r 2=0.63; P<0.001). The longitudinal analysis of the five women and five men with the highest number of participations showed that performance decreased in one female (r 2=0.45; P=0.01). The four other women as well as all five men showed no change in overall race times across years. Conclusions Participation increased and performance improved for male Triple Iron ultra-triathletes while participation remained unchanged and performance decreased for females between 1988 and 2011. The reasons for the increase of the gap between female and male Triple Iron ultra-triathletes need further investigations. PMID:23012633

A comparison of remote vs. local influence of El Niño on the coastal circulation of the northeast Pacific

NASA Astrophysics Data System (ADS)

Hermann, Albert J.; Curchitser, Enrique N.; Haidvogel, Dale B.; Dobbins, Elizabeth L.

2009-12-01

A set of spatially nested circulation models is used to explore interannual change in the northeast Pacific (NEP) during 1997-2002, and remote vs. local influence of the 1997-1998 El Niño on this region. Our nested set is based on the primitive equations of motion, and includes a basin-scale model of the north Pacific at ˜40-km resolution (NPac), and a regional model of the Northeast Pacific at ˜10-km resolution. The NEP model spans an area from Baja California through the Bering Sea, from the coast to ˜2000-km offshore. In this context, "remote influence" refers to effects driven by changes in ocean velocity and temperature outside of the NEP domain; "local influence" refers to direct forcing by winds and runoff within the NEP domain. A base run of this model using hindcast winds and runoff for 1996-2002 replicates the dominant spatial modes of sea-surface height anomalies from satellite data, and coastal sea level from tide gauges. We have performed a series of sensitivity runs with the NEP model for 1997-1998, which analyze the response of coastal sea level to: (1) hindcast winds and coastal runoff, as compared to their monthly climatologies and (2) hindcast boundary conditions (from the NPac model), as compared to their monthly climatologies. Results indicate penetration of sea-surface height (SSH) from the basin-scale model into the NEP domain (e.g., remote influence), with propagation as coastal trapped waves from Baja up through Alaska. Most of the coastal sea-level anomaly off Alaska in El Niño years appears due to direct forcing by local winds and runoff (local influence), and such anomalies are much stronger than those produced off California. We quantify these effects as a function of distance along the coastline, and consider how they might impact the coastal ecosystems of the NEP.

Personal best times in an Olympic distance triathlon and in a marathon predict Ironman race time in recreational male triathletes.

PubMed

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Lepers, Romuald

2011-01-01

The purpose of this study was to define predictor variables for recreational male Ironman triathletes, using age and basic measurements of anthropometry, training, and previous performance to establish an equation for the prediction of an Ironman race time for future recreational male Ironman triathletes. Age and anthropometry, training, and previous experience variables were related to Ironman race time using bivariate and multivariate analysis. A total of 184 recreational male triathletes, of mean age 40.9 ± 8.4 years, height 1.80 ± 0.06 m, and weight 76.3 ± 8.4 kg completed the Ironman within 691 ± 83 minutes. They spent 13.9 ± 5.0 hours per week in training, covering 6.3 ± 3.1 km of swimming, 194.4 ± 76.6 km of cycling, and 45.0 ± 15.9 km of running. In total, 149 triathletes had completed at least one marathon, and 150 athletes had finished at least one Olympic distance triathlon. They had a personal best time of 130.4 ± 44.2 minutes in an Olympic distance triathlon and of 193.9 ± 31.9 minutes in marathon running. In total, 126 finishers had completed both an Olympic distance triathlon and a marathon. After multivariate analysis, both a personal best time in a marathon (P < 0.0001) and in an Olympic distance triathlon (P < 0.0001) were the best variables related to Ironman race time. Ironman race time (minutes) might be partially predicted by the following equation: (r (2) = 0.65, standard error of estimate = 56.8) = 152.1 + 1.332 × (personal best time in a marathon, minutes) + 1.964 × (personal best time in an Olympic distance triathlon, minutes). These results suggest that, in contrast with anthropometric and training characteristics, both the personal best time in an Olympic distance triathlon and in a marathon predict Ironman race time in recreational male Ironman triathletes.

Personal best times in an Olympic distance triathlon and in a marathon predict Ironman race time in recreational male triathletes

PubMed Central

Rüst, Christoph Alexander; Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas; Lepers, Romuald

2011-01-01

Background The purpose of this study was to define predictor variables for recreational male Ironman triathletes, using age and basic measurements of anthropometry, training, and previous performance to establish an equation for the prediction of an Ironman race time for future recreational male Ironman triathletes. Methods Age and anthropometry, training, and previous experience variables were related to Ironman race time using bivariate and multivariate analysis. Results A total of 184 recreational male triathletes, of mean age 40.9 ± 8.4 years, height 1.80 ± 0.06 m, and weight 76.3 ± 8.4 kg completed the Ironman within 691 ± 83 minutes. They spent 13.9 ± 5.0 hours per week in training, covering 6.3 ± 3.1 km of swimming, 194.4 ± 76.6 km of cycling, and 45.0 ± 15.9 km of running. In total, 149 triathletes had completed at least one marathon, and 150 athletes had finished at least one Olympic distance triathlon. They had a personal best time of 130.4 ± 44.2 minutes in an Olympic distance triathlon and of 193.9 ± 31.9 minutes in marathon running. In total, 126 finishers had completed both an Olympic distance triathlon and a marathon. After multivariate analysis, both a personal best time in a marathon (P < 0.0001) and in an Olympic distance triathlon (P < 0.0001) were the best variables related to Ironman race time. Ironman race time (minutes) might be partially predicted by the following equation: (r2 = 0.65, standard error of estimate = 56.8) = 152.1 + 1.332 × (personal best time in a marathon, minutes) + 1.964 × (personal best time in an Olympic distance triathlon, minutes). Conclusion These results suggest that, in contrast with anthropometric and training characteristics, both the personal best time in an Olympic distance triathlon and in a marathon predict Ironman race time in recreational male Ironman triathletes. PMID:24198578

Tall-tower observations of pollution from near-field sources in central Texas during the Texas Air Quality Study 2006

NASA Astrophysics Data System (ADS)

Andrews, A. E.; Kort, E.; Hirsch, A.; Eluszkiewicz, J.; Nehrkorn, T.; Michalak, A. M.; Petron, G.; Frost, G. J.; Gurney, K. R.; Stohl, A.; Wofsy, S. C.; Angevine, W. M.; White, A. B.; Oltmans, S. J.; Montzka, S. A.; Tans, P. P.

2008-12-01

The NOAA Earth System Research Laboratory has been measuring CO2, CO and basic meteorology from a television transmitter tower outside of Waco, TX since 2001. Sample intakes are located at 30, 122 and 457 meters above ground level. From July through November 2006, O3 measurements were added at 9 and 457 magl to support the Texas Air Quality Study (TexAQS 2006). There are several large point sources and metropolitan areas in the vicinity of the tower with distinct chemical signatures. Here, we evaluate the extent to which the Stochastic Time Inverted Lagrangian Transport (STILT) model reproduces pollution events that were observed at the tower during summer and fall 2006. For this study, STILT is driven by customized output from the WRF model v2.2, which was run with a 2km nested grid surrounding the tower embedded in a 10km nest that covers most of the southern and eastern US and a 40km nest that includes all of North America. Inaccurate representation of atmospheric transport is a major source of error in inverse estimates of fluxes of CO2 and other gases, and we selected this period for in depth analysis in part because a dense network of radar profilers was deployed for TexAQS 2006. The radar profilers report wind and boundary layer height, which can be used to evaluate the fidelity of the simulated transport. STILT is a particle dispersion model that can be run either forward or backward in time, which allows us to compare the agreement between forward runs from individual pollution sources and backward runs from the tower. We will also quantitatively compare the STILT-WRF results with similar output from the FLEXPART particle dispersion model driven by high-resolution ECMWF meteorological fields. We will use several different emissions inventories to evaluate model-to-model differences and differences between modeled and observed pollution influences.

Dynamical Downscaling of Seasonal Climate Prediction over Nordeste Brazil with ECHAM3 and NCEP's Regional Spectral Models at IRI.

NASA Astrophysics Data System (ADS)

Nobre, Paulo; Moura, Antonio D.; Sun, Liqiang

2001-12-01

This study presents an evaluation of a seasonal climate forecast done with the International Research Institute for Climate Prediction (IRI) dynamical forecast system (regional model nested into a general circulation model) over northern South America for January-April 1999, encompassing the rainy season over Brazil's Nordeste. The one-way nesting is one in two tiers: first the NCEP's Regional Spectral Model (RSM) runs with an 80-km grid mesh forced by the ECHAM3 atmospheric general circulation model (AGCM) outputs; then the RSM runs with a finer grid mesh (20 km) forced by the forecasts generated by the RSM-80. An ensemble of three realizations is done. Lower boundary conditions over the oceans for both ECHAM and RSM model runs are sea surface temperature forecasts over the tropical oceans. Soil moisture is initialized by ECHAM's inputs. The rainfall forecasts generated by the regional model are compared with those of the AGCM and observations. It is shown that the regional model at 80-km resolution improves upon the AGCM rainfall forecast, reducing both seasonal bias and root-mean-square error. On the other hand, the RSM-20 forecasts presented larger errors, with spatial patterns that resemble those of local topography. The better forecast of the position and width of the intertropical convergence zone (ITCZ) over the tropical Atlantic by the RSM-80 model is one of the principal reasons for better-forecast scores of the RSM-80 relative to the AGCM. The regional model improved the spatial as well as the temporal details of rainfall distribution, and also presenting the minimum spread among the ensemble members. The statistics of synoptic-scale weather variability on seasonal timescales were best forecast with the regional 80-km model over the Nordeste. The possibility of forecasting the frequency distribution of dry and wet spells within the rainy season is encouraging.

Oxygen consumption and gait variables of Arabian endurance horses measured during a field exercise test.

PubMed

Cottin, F; Metayer, N; Goachet, A G; Julliand, V; Slawinski, J; Billat, V; Barrey, E

2010-11-01

Arabian horses have morphological, muscular and metabolic features designed for endurance races. Their gas exchange and gait variables were therefore measured during a field exercise test. This study presents original respiratory and locomotor data recorded in endurance horses under field conditions. Respiratory gas exchange ratio (RER) of Arabian horses at the speed required to win endurance races (18 km/h for 120-160 km) are <1 and running economy (RE) is also low in order to maintain exercise intensity using aerobic metabolism for long intervals. The purpose of this study was to measure oxygen consumption and gait variables in Arabian endurance horses running in the field in order to estimate RER and RE. Five Arabian horses trained for endurance racing were test ridden at increasing speeds on the field. Their speed was recorded and controlled by the rider using a GPS logger. Each horse was equipped with a portable respiratory gas analyser, which measured breath-by-breath respiratory variables and heart rate. The gait variables were recorded using tri-axial accelerometer data loggers and software for gait analysis. Descriptive statistics and linear regressions were used to analyse the speed related changes in each variable with P < 0.05 taken as significant. At a canter speed corresponding to endurance race winning speed (18 km/h), horses presented a VO(2) = 42 ± 9 ml/min/kg bwt, RER = 0.96 ± 0.10 and RE (= VO(2) /speed) = 134 ± 27 l/km/kg bwt. Linear relationships were observed between speed and VO(2,) HR and gait variables. Significant correlations were observed between VO(2) and gait variables. The RER of 0.96 at winning endurance speed indicates that Arabian horses mainly use aerobic metabolism based on lipid oxidation and that RER may also be related to a good coordination between running speed, respiratory and gait parameters. © 2010 EVJ Ltd.

Sex difference in Double Iron ultra-triathlon performance

PubMed Central

2013-01-01

Background The present study examined the sex difference in swimming (7.8 km), cycling (360 km), running (84 km), and overall race times for Double Iron ultra-triathletes. Methods Sex differences in split times and overall race times of 1,591 men and 155 women finishing a Double Iron ultra-triathlon between 1985 and 2012 were analyzed. Results The annual number of finishes increased linearly for women and exponentially for men. Men achieved race times of 1,716 ± 243 min compared to 1,834 ± 261 min for women and were 118 ± 18 min (6.9%) faster (p < 0.01). Men finished swimming within 156 ± 63 min compared to women with 163 ± 31 min and were 8 ± 32 min (5.1 ± 5.0%) faster (p < 0.01). For cycling, men (852 ± 196 min) were 71 ± 70 min (8.3 ± 3.5%) faster than women (923 ± 126 min) (p < 0.01). Men completed the run split within 710 ± 145 min compared to 739 ± 150 min for women and were 30 ± 5 min (4.2 ± 3.4%) faster (p = 0.03). The annual three fastest men improved race time from 1,650 ± 114 min in 1985 to 1,339 ± 33 min in 2012 (p < 0.01). Overall race time for women remained unchanged at 1,593 ± 173 min with an unchanged sex difference of 27.1 ± 8.6%. In swimming, the split times for the annual three fastest women (148 ± 14 min) and men (127 ± 20 min) remained unchanged with an unchanged sex difference of 26.8 ± 13.5%. In cycling, the annual three fastest men improved the split time from 826 ± 60 min to 666 ± 18 min (p = 0.02). For women, the split time in cycling remained unchanged at 844 ± 54 min with an unchanged sex difference of 25.2 ± 7.3%. In running, the annual fastest three men improved split times from 649 ± 77 min to 532 ± 16 min (p < 0.01). For women, however, the split times remained unchanged at 657 ± 70 min with a stable sex difference of 32.4 ± 12.5%. Conclusions To summarize, the present findings showed that men were faster than women in Double Iron ultra-triathlon, men improved overall race times, cycling and running split times, and the sex difference remained unchanged across years for overall race time and split times. The sex differences for overall race times and split times were higher than reported for Ironman triathlon. PMID:23849631

Cruise Report, INDOPAC Expedition, Legs 9 through 16.

DTIC Science & Technology

1977-11-23

a run in the Mergui-North Sumatra Basin . geological and geophysical study of the About 2700 km of multi-channel seismic Andaman Sea. Previous...in the Mergui-North Sumatra runs and large shots were monitored by the Basin was launched. The moored buoy was at M.O.C. shore station . the north...and including Nias Island. The SN fore-arc basin lying between this nonvolcanic ridge and Sumatra is a/ .• • • ••. •~~~~ \\ subsiding zone

Comparing the physical demands of friendly matches and small-sided games in semiprofessional soccer players.

PubMed

Casamichana, David; Castellano, Julen; Castagna, Carlo

2012-03-01

This study compared the physical demands of friendly matches (FMs) and small-sided games (SGs) in semiprofessional soccer players by means of global positioning system technology. Twenty-seven semiprofessional soccer players were monitored during 7 FMs and 9 sessions involving different SGs. Their physical profile was described on the basis of 20 variables related to distances and frequencies at different running speeds, the number of accelerations, and through global indicators of workload such as the work:rest ratio, player workload, and the exertion index. Results showed significant differences (p < 0.01) between SGs and FMs for the following variables: overall workload (SG > FM); the distribution of the distance covered in the speed zones 7.0-12.9 km·h(-1) (SG > FM) and >21 km·h(-1) (FM > SG); the distribution of time spent in certain speed zones (FM > SG: 0.0-6.9 and >21 km·h(-1); FM > SG: 7.0-12.9 km·h(-1)). More sprints per hour of play were performed during FMs, with greater mean durations and distances, greater maximum durations and distances, and a greater frequency per hour of play for sprints of 10-40 and >40 m (p < 0.01). The frequency of repeated high-intensity efforts was higher during FM (p < 0.01). The results show that coaches and strength and conditioning professionals should consider FMs during their training routine to foster specific adaptations in the domain of high-intensity effort.

Run-off regime of the small rivers in mountain landscapes (on an example of the mountain "Mongun-taiga

NASA Astrophysics Data System (ADS)

Pryahina, G.; Zelepukina, E.; Guzel, N.

2012-04-01

Hydrological characteristics calculations of the small mountain rivers in the basins with glaciers frequently cause complexity in connection with absence of standard hydrological supervision within remote mountain territories. The unique way of the actual information reception on a water mode of such rivers is field work. The rivers of the mountain Mongun-taiga located on a joint of Altai and Sayan mountains became hydrological researches objects of Russian geographical society complex expeditions in 2010-2011. The Mongun-taiga cluster of international biosphere reserve "Ubsunurskaya hollow" causes heightened interest of researchers — geographers for many years. The original landscape map in scale 1:100000 has been made, hydrological supervision on the rivers East Mugur and ugur, belonging inland basin of Internal Asia are lead. Supervision over the river drain East Mugur runoff were spent in profile of glacier tongue (the freezing area - 22 % (3.2 km2) from the reception basin) and in the closing alignment of the river located on distance of 3,4 km below tongue of glacier. During researches following results have been received. During the ablation period diurnal fluctuations with a strongly shown maximum and minimum of water discharges are typically for the small rivers with considerable share of a glacial food. The run-off maximum from the glacier takes place from 2 to 7 p.m., the run-off minimum is observed early in the morning. High speed of thawed snow running-off from glacier tongue and rather small volume of dynamic stocks water on an ice surface lead to growth of water discharge. In the bottom profile the time of maximum and minimum of water discharge is displaced on the average 2 hours, it depends of the water travel time. Maximum glacial run-off discharge (1.12 m3/s) in the upper profile was registered on July 16 (it was not rain). Volumes of daily runoff in the upper and bottom profiles were 60700-67600 m3 that day. The run-off from nonglacial part of the basin is formed by underground waters and melting snowfields, during the absence of rainfall period the part of one amounted to 10% of the run-off in the lower profile. We suggest that this water discharge corresponds to base flow value in the lower profile because the area of snowfields of the basin was < 0.1 km2 that year. Run-off monitoring has showed that rivers with a small glacial food are characterized by absence of diurnal balance of runoff. During rainfall the water content of river has being increased due to substantial derivation of basin and, as a result, fast flowing rain water into bed of river. The sharp decrease in water content of river during periods of rainfall absence indicates low inventory of soil and groundwater and the low rate of glacial. Thus, glaciers and character of the relief influence the formation of run-off small mountain rivers. Results of researches will be used for mathematical modeling mountain rivers run-off.

Snowmelt-runoff Model Utilizing Remotely-sensed Data

NASA Technical Reports Server (NTRS)

Rango, A.

1985-01-01

Remotely sensed snow cover information is the critical data input for the Snowmelt-Runoff Model (SRM), which was developed to simulatke discharge from mountain basins where snowmelt is an important component of runoff. Of simple structure, the model requires only input of temperature, precipitation, and snow covered area. SRM was run successfully on two widely separated basins. The simulations on the Kings River basin are significant because of the large basin area (4000 sq km) and the adequate performance in the most extreme drought year of record (1976). The performance of SRM on the Okutadami River basin was important because it was accomplished with minimum snow cover data available. Tables show: optimum and minimum conditions for model application; basin sizes and elevations where SRM was applied; and SRM strengths and weaknesses. Graphs show results of discharge simulation.

Real-Time Eddy-Resolving Ocean Prediction in the Caribbean

NASA Astrophysics Data System (ADS)

Hurlburt, H. E.; Smedstad, O. M.; Shriver, J. F.; Townsend, T. L.; Murphy, S. J.

2001-12-01

A {1/16}o eddy-resolving, nearly global ocean prediction system has been developed by the Naval Research Laboratory (NRL), Stennis Space Center, MS. It has been run in real-time by the Naval Oceanographic Office (NAVO), Stennis Space Center, MS since 18 Oct 2000 with daily updates for the nowcast and 30-day forecasts performed every Wednesday. The model has ~8 km resolution in the Caribbean region and assimilates real-time altimeter sea surface height (SSH) data from ERS-2, GFO and TOPEX/POSEIDON plus multi-channel sea surface temperature (MCSST) from satellite IR. Real-time and archived results from the system can be seen at web site: http://www7320.nrlssc.navy.mil/global\

A reduced core to skin temperature gradient, not a critical core temperature, affects aerobic capacity in the heat.

PubMed

Cuddy, John S; Hailes, Walter S; Ruby, Brent C

2014-07-01

The purpose of this study was to determine the impact of the core to skin temperature gradient during incremental running to volitional fatigue across varying environmental conditions. A secondary aim was to determine if a "critical" core temperature would dictate volitional fatigue during running in the heat. 60 participants (n=49 male, n=11 female; 24±5 yrs, 177±11 cm, 75±13 kg) completed the study. Participants were uniformly stratified into a specific exercise temperature group (18 °C, 26 °C, 34 °C, or 42 °C) based on a 3-mile run performance. Participants were equipped with core and chest skin temperature sensors and a heart rate monitor, entered an environmental chamber (18 °C, 26 °C, 34 °C, or 42 °C), and rested in the seated position for 10 min before performing a walk/run to volitional exhaustion. Initial treadmill speed was 3.2 km h(-1) with a 0% grade. Every 3 min, starting with speed, speed and grade increased in an alternating pattern (speed increased by 0.805 km h(-1), grade increased by 0.5%). Time to volitional fatigue was longer for the 18 °C and 26 °C group compared to the 42 °C group, (58.1±9.3 and 62.6±6.5 min vs. 51.3±8.3 min, respectively, p<0.05). At the half-way point and finish, the core to skin gradient for the 18 °C and 26 °C groups was larger compared to 42 °C group (halfway: 2.6±0.7 and 2.0±0.6 vs. 1.3±0.5 for the 18 °C, 26 °C and 42 °C groups, respectively; finish: 3.3±0.7 and 3.5±1.1 vs. 2.1±0.9 for the 26 °C, 34 °C, and 42 °C groups, respectively, p<0.05). Sweat rate was lower in the 18 °C group compared to the 26 °C, 34 °C, and 42 °C groups, 3.6±1.3 vs. 7.2±3.0, 7.1±2.0, and 7.6±1.7 g m(-2) min(-1), respectively, p<0.05. There were no group differences in core temperature and heart rate response during the exercise trials. The current data demonstrate a 13% and 22% longer run time to exhaustion for the 18 °C and 26 °C group, respectively, compared to the 42 °C group despite no differences in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of air quality model resolution on uncertainty associated with health impacts

NASA Astrophysics Data System (ADS)

Thompson, T. M.; Selin, N. E.

2012-06-01

We use regional air quality modeling to evaluate the impact of model resolution on uncertainty associated with the human health benefits resulting from proposed air quality regulations. Using a regional photochemical model (CAMx), we ran a modeling episode with meteorological inputs representing conditions as they occurred during August through September 2006, and two emissions inventories (a 2006 base case and a 2018 proposed control scenario, both for Houston, Texas) at 36, 12, 4 and 2 km resolution. The base case model performance was evaluated for each resolution against daily maximum 8-h averaged ozone measured at monitoring stations. Results from each resolution were more similar to each other than they were to measured values. Population-weighted ozone concentrations were calculated for each resolution and applied to concentration response functions (with 95% confidence intervals) to estimate the health impacts of modeled ozone reduction from the base case to the control scenario. We found that estimated avoided mortalities were not significantly different between 2, 4 and 12 km resolution runs, but 36 km resolution may over-predict some potential health impacts. Given the cost/benefit analysis requirements of the Clean Air Act, the uncertainty associated with human health impacts and therefore the results reported in this study, we conclude that health impacts calculated from population weighted ozone concentrations obtained using regional photochemical models at 36 km resolution fall within the range of values obtained using fine (12 km or finer) resolution modeling. However, in some cases, 36 km resolution may not be fine enough to statistically replicate the results achieved using 2 and 4 km resolution. On average, when modeling at 36 km resolution, 7 deaths per ozone month were avoided because of ozone reductions resulting from the proposed emissions reductions (95% confidence interval was 2-9). When modeling at 2, 4 or 12 km finer scale resolution, on average 5 deaths were avoided due to the same reductions (95% confidence interval was 2-7). Initial results for this specific region show that modeling at a resolution finer than 12 km is unlikely to improve uncertainty in benefits analysis. We suggest that 12 km resolution may be appropriate for uncertainty analyses in areas with similar chemistry, but that resolution requirements should be assessed on a case-by-case basis and revised as confidence intervals for concentration-response functions are updated.

VizieR Online Data Catalog: VLBI Ecliptic Plane Survey: VEPS-1 (Shu+, 2017)

NASA Astrophysics Data System (ADS)

Shu, F.; Petrov, L.; Jiang, W.; Xia, B.; Jiang, T.; Cui, Y.; Takefuji, K.; McCallum, J.; Lovell, J.; Yi, S.-O.; Hao, L.; Yang, W.; Zhang, H.; Chen, Z.; Li, J.

2017-08-01

We began observations in the search mode in 2015 February. The participating stations included the three core stations of the Chinese VLBI Network (CVN): seshan25, kunming, and urumqi. Depending on the participating stations, the longest baseline length in each session can be varied from 3200km to 9800km. Our observations were performed at a 2048Mbps data rate, with 16 Intermediate Frequency (IF) channels and 2-bit sampling. The first eight IFs of 32MHz bandwidth were distributed in the range of [8.188, 8.444]GHz, and the remaining eight IFs of 32MHz bandwidth were in the range of [8.700, 8.956]GHz. Table 1: Summary of the VLBI Ecliptic Plane Survey (VEPS) observations in search mode: --------------------------------------------------- Date Dur. Code Stations Number of (Y/M/D) (h) Targets --------------------------------------------------- 2015 Feb 13 24 VEPS01 ShKmUr 293 2015 Feb 14 24 VEPS02 ShKmUr 338 2015 Apr 23 24 VEPS03 UrKv 300 2015 Apr 24 24 VEPS04 ShKmUrKv 400 2015 Aug 10 25 VEPS05 ShKmKvHo 252 2015 Aug 19 25 VEPS06 ShKmKvHo 277 2016 Mar 02 24 VEPS07 ShKmUrKb 333 2016 Mar 11 24 VEPS08 ShKmUrKb 477 2016 May 13 24 VEPS09 ShUrHo 291 2016 May 14 22 VEPS10 ShUrKv 322 2016 Jul 06 24 VEPS11 ShUrKb 307 2016 Sep 02 23 VEPS12 ShUr 424 2016 Sep 03 23 VEPS13 ShKmUr 344 --------------------------------------------------- Sh=Seshan25; Km=Kunming; Ur=Urumqi; Kv=Sejong; Kb=Kashim34; Ho=Hobart26. --------------------------------------------------- We ran two absolute astrometry dual-band VLBA programs that targeted ecliptic plane compact radio sources: the dedicated survey of weak ecliptic plane calibrators with the VLBA BS250 program in 2016 March-May, and the VLBA Calibrator Survey 9 (VCS-9) in 2015 August-2016 September. The International VLBI Service for Geodesy and Astrometry (IVS) runs a number of VLBI observing programs. We made an attempt to improve the coordinates of some VEPS sources detected in the search mode and provide additional measurements of telescope position with the same experiments in two such 24hr sessions, AOV010 in July and AUA012 in 2016 August. (2 data files).

Near-Infrared Spectroscopy: More Accurate Than Heart Rate for Monitoring Intensity in Running in Hilly Terrain.

PubMed

Born, Dennis-Peter; Stöggl, Thomas; Swarén, Mikael; Björklund, Glenn

2017-04-01

To investigate the cardiorespiratory and metabolic response of trail running and evaluate whether heart rate (HR) adequately reflects the exercise intensity or if the tissue-saturation index (TSI) could provide a more accurate measure during running in hilly terrain. Seventeen competitive runners (4 women, V̇O 2 max, 55 ± 6 mL · kg -1 · min -1 ; 13 men, V̇O 2 max, 68 ± 6 mL · kg -1 · min -1 ) performed a time trial on an off-road trail course. The course was made up of 2 laps covering a total distance of 7 km and included 6 steep uphill and downhill sections with an elevation gain of 486 m. All runners were equipped with a portable breath-by-breath gas analyzer, HR belt, global positioning system receiver, and near-infrared spectroscopy (NIRS) device to measure the TSI. During the trail run, the exercise intensity in the uphill and downhill sections was 94% ± 2% and 91% ± 3% of maximal heart rate, respectively, and 84% ± 8% and 68% ± 7% of V̇O 2 max, respectively. The oxygen uptake (V̇O 2 ) increased in the uphill sections and decreased in the downhill sections (P < .01). Although HR was unaffected by the altering slope conditions, the TSI was inversely correlated to the changes in V̇O 2 (r = -.70, P < .05). HR was unaffected by the continuously changing exercise intensity; however, TSI reflected the alternations in V̇O 2 . Recently used exclusively for scientific purposes, this NIRS-based variable may offer a more accurate alternative than HR to monitor running intensity in the future, especially for training and competition in hilly terrain.

Detecting Outliers in Marathon Data by Means of the Andrews Plot

NASA Astrophysics Data System (ADS)

Stehlík, Milan; Wald, Helmut; Bielik, Viktor; Petrovič, Juraj

2011-09-01

For an optimal race performance, it is important, that the runner keeps steady pace during most of the time of the competition. First time runners or athletes without many competitions often experience an "blow out" after a few kilometers of the race. This could happen, because of strong emotional experiences or low control of running intensity. Competition pace of half marathon of the middle level recreational athletes is approximately 10 sec quicker than their training pace. If an athlete runs the first third of race (7 km) at a pace that is 20 sec quicker than is his capacity (trainability), he would experience an "blow out" in the last third of the race. This would be reflected by reducing the running intensity and inability to keep steady pace in the last kilometers of the race and in the final time as well. In sports science, there are many diagnostic methods ([3], [2], [6]) that are used for prediction of optimal race pace tempo and final time. Otherwise there is lacking practical evidence of diagnostics methods and its use in the field (competition, race). One of the conditions that needs to be carried out is that athletes have not only similar final times, but it is important that they keep constant pace as much as possible during whole race. For this reason it is very important to find outliers. Our experimental group consisted of 20 recreational trained athletes (mean age 32,6 years±8,9). Before the race the athletes were instructed to run on the basis of their subjective feeling and previous experience. The data (running pace of each kilometer, average and maximal heart rate of each kilometer) were collected by GPS-enabled personal trainer Forerunner 305.

Comparison of Upright Gait with Supine Bungee-Cord Gait

NASA Technical Reports Server (NTRS)

Boda, Wanda L.; Hargens, Alan R.; Campbell, J. A.; Yang, C.; Holton, Emily M. (Technical Monitor)

1998-01-01

Running on a treadmill with bungee-cord resistance is currently used on the Russian space station MIR as a countermeasure for the loss of bone and muscular strength which occurs during spaceflight. However, it is unknown whether ground reaction force (GRF) at the feet using bungee-cord resistance is similar to that which occurs during upright walking and running on Earth. We hypothesized-that the DRAMs generated during upright walking and running are greater than the DRAMs generated during supine bungee-cord gait. Eleven healthy subjects walked (4.8 +/- 0.13 km/h, mean +/- SE) and ran (9.1 +/- 0.51 km/h) during upright and supine bungee-cord exercise on an active treadmill. Subjects exercised for 3 min in each condition using a resistance of 1 body weight calibrated during an initial, stationary standing position. Data were sampled at a frequency of 500Hz and the mean of 3 trials was analyzed for each condition. A repeated measures analysis of variance tested significance between the conditions. Peak DRAMs during upright walking were significantly greater (1084.9 +/- 111.4 N) than during supine bungee-cord walking (770.3 +/- 59.8 N; p less than 0.05). Peak GRFs were also significantly greater for upright running (1548.3 +/- 135.4 N) than for supine bungee-cord running (1099.5 +/- 158.46 N). Analysis of GRF curves indicated that forces decreased throughout the stance phase for bungee-cord gait but not during upright gait. These results indicate that bungee-cord exercise may not create sufficient loads at the feet to counteract the loss of bone and muscular strength that occurs during long-duration exposure to microgravity.

High-resolution dynamical downscaling of the future Alpine climate

NASA Astrophysics Data System (ADS)

Bozhinova, Denica; José Gómez-Navarro, Juan; Raible, Christoph

2017-04-01

The Alpine region and Switzerland is a challenging area for simulating and analysing Global Climate Model (GCM) results. This is mostly due to the combination of a very complex topography and the still rather coarse horizontal resolution of current GCMs, in which not all of the many-scale processes that drive the local weather and climate can be resolved. In our study, the Weather Research and Forecasting (WRF) model is used to dynamically downscale a GCM simulation to a resolution as high as 2 km x 2 km. WRF is driven by initial and boundary conditions produced with the Community Earth System Model (CESM) for the recent past (control run) and until 2100 using the RCP8.5 climate scenario (future run). The control run downscaled with WRF covers the period 1976-2005, while the future run investigates a 20-year-slice simulated for the 2080-2099. We compare the control WRF-CESM simulations to an observational product provided by MeteoSwiss and an additional WRF simulation driven by the ERA-Interim reanalysis, to estimate the bias that is introduced by the extra modelling step of our framework. Several bias-correction methods are evaluated, including a quantile mapping technique, to ameliorate the bias in the control WRF-CESM simulation. In the next step of our study these corrections are applied to our future WRF-CESM run. The resulting downscaled and bias-corrected data is analysed for the properties of precipitation and wind speed in the future climate. Our special interest focuses on the absolute quantities simulated for these meteorological variables as these are used to identify extreme events, such as wind storms and situations that can lead to floods.

Momentum-driven Winds from Radiatively Efficient Black Hole Accretion and Their Impact on Galaxies

NASA Astrophysics Data System (ADS)

Brennan, Ryan; Choi, Ena; Somerville, Rachel S.; Hirschmann, Michaela; Naab, Thorsten; Ostriker, Jeremiah P.

2018-06-01

We explore the effect of momentum-driven winds representing radiation-pressure-driven outflows from accretion onto supermassive black holes in a set of numerical hydrodynamical simulations. We explore two matched sets of cosmological zoom-in runs of 24 halos with masses ∼1012.0–1013.4 M ⊙ run with two different feedback models. Our “NoAGN” model includes stellar feedback via UV heating, stellar winds and supernovae, photoelectric heating, and cosmic X-ray background heating from a metagalactic background. Our fiducial “MrAGN” model is identical except that it also includes a model for black hole seeding and accretion, as well as heating and momentum injection associated with the radiation from black hole accretion. Our MrAGN model launches galactic outflows, which result in both “ejective” feedback—the outflows themselves that drive gas out of galaxies—and “preventative” feedback, which suppresses the inflow of new and recycling gas. As much as 80% of outflowing galactic gas can be expelled, and accretion can be suppressed by as much as a factor of 30 in the MrAGN runs when compared with the NoAGN runs. The histories of NoAGN galaxies are recycling dominated, with ∼70% of material that leaves the galaxy eventually returning, and the majority of outflowing gas reaccretes on 1 Gyr timescales without AGN feedback. Outflowing gas in the MrAGN runs has a higher characteristic velocity (500–1000 km s‑1 versus 100–300 km s‑1 for outflowing NoAGN gas) and travels as far as a few megaparsecs. Only ∼10% of ejected material is reaccreted in the MrAGN galaxies.

Evaluating the Sensitivity of Glacial Isostatic Adjustment to a Hydrous Melt at 410 km Depth

NASA Astrophysics Data System (ADS)

Hill, A. M.; Milne, G. A.; Ranalli, G.

2017-12-01

We present a sensitivity analysis aimed at testing whether observables related to GIA can support or refute the existence of a low viscosity partial melt layer located above the mantle transition zone, as required by the so-called "Transition Zone Water Filter" model (Bercovici and Karato 2003). In total, 400 model runs were performed sampling a range of melt layer thicknesses (1, 10 & 20 km) and viscosities (1015 - 1019 Pas) as well as plausible viscosity values in the upper and lower mantle. Comparing model output of postglacial decay times and j2, 18 of the considered viscosity models were found to be compatible with all of the observational constraints. Amongst these, only three `background' upper and lower mantle viscosities are permitted regardless of the properties of the melt layer: an upper mantle value of 3×1020 Pas and lower mantle values of 1022, 3×1022 and 5×1022 Pas. Concerning the properties of the melt layer itself, a thin (1 km) layer may have any of the investigated viscosities (1015 to 1019 Pas). For thicker melt layers, the viscosity must be ≥1018 Pas (20 km) or ≥1017 Pas (10 km). Our results indicate clear parameter trade-offs between the properties of the melt layer and the background viscosity structure. Given that the observations permit several values of lower mantle viscosity, we conclude that tightening constraints on this parameter would be valuable for future investigation of the type presented here. Furthermore, while decay times from both locations considered in this investigation (Ångerman River, Sweden; Richmond Gulf, Canada) offer meaningful constraints on viscosity structure, the value for Richmond Gulf is significantly more uncertain and so increasing its precision would likely result in improved viscosity constraints.

Sensitivity studies of high-resolution RegCM3 simulations of precipitation over the European Alps: the effect of lateral boundary conditions and domain size

NASA Astrophysics Data System (ADS)

Nadeem, Imran; Formayer, Herbert

2016-11-01

A suite of high-resolution (10 km) simulations were performed with the International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3) to study the effect of various lateral boundary conditions (LBCs), domain size, and intermediate domains on simulated precipitation over the Great Alpine Region. The boundary conditions used were ECMWF ERA-Interim Reanalysis with grid spacing 0.75∘, the ECMWF ERA-40 Reanalysis with grid spacing 1.125 and 2.5∘, and finally the 2.5∘ NCEP/DOE AMIP-II Reanalysis. The model was run in one-way nesting mode with direct nesting of the high-resolution RCM (horizontal grid spacing Δx = 10 km) with driving reanalysis, with one intermediate resolution nest (Δx = 30 km) between high-resolution RCM and reanalysis forcings, and also with two intermediate resolution nests (Δx = 90 km and Δx = 30 km) for simulations forced with LBC of resolution 2.5∘. Additionally, the impact of domain size was investigated. The results of multiple simulations were evaluated using different analysis techniques, e.g., Taylor diagram and a newly defined useful statistical parameter, called Skill-Score, for evaluation of daily precipitation simulated by the model. It has been found that domain size has the major impact on the results, while different resolution and versions of LBCs, e.g., 1.125∘ ERA40 and 0.7∘ ERA-Interim, do not produce significantly different results. It is also noticed that direct nesting with reasonable domain size, seems to be the most adequate method for reproducing precipitation over complex terrain, while introducing intermediate resolution nests seems to deteriorate the results.

Interaction effects of stride angle and strike pattern on running economy.

PubMed

Santos-Concejero, J; Tam, N; Granados, C; Irazusta, J; Bidaurrazaga-Letona, I; Zabala-Lili, J; Gil, S M

2014-12-01

This study aimed to investigate the relationship between stride angle and running economy (RE) in athletes with different foot strike patterns. 30 male runners completed 4 min running stages on a treadmill at different velocities. During the test, biomechanical variables such as stride angle, swing time, contact time, stride length and frequency were recorded using an optical measurement system. Their foot strike pattern was determined, and VO2 at velocities below the lactate threshold were measured to calculate RE. Midfoot/forefoot strikers had better RE than rearfoot strikers (201.5±5.6 ml · kg(-1) · km(-1) vs. 213.5±4.2 ml · kg(-1) · km(-1)respectively; p=0.019). Additionally, midfoot/fore-foot strikers presented higher stride angles than rearfoot strikers (p=0.043). Linear modelling analysis showed that stride angle is closely related to RE (r=0.62, p<0.001) and that the effect of stride angle on RE was different in the 2 groups. From an arbitrary value of 4°, a rearfoot strike pattern is likely to be more economical, whereas at any lower degree, the midfoot/forefoot strike pattern appears to be more desirable. A biomechanical running technique characterised by high stride angles and a midfoot/forefoot strike pattern is advantageous for a better RE. Athletes may find stride angle useful for improving RE. © Georg Thieme Verlag KG Stuttgart · New York.

The genetics of human running: ACTN3 polymorphism as an evolutionary tool improving the energy economy during locomotion.

PubMed

Pasqua, Leonardo A; Bueno, Salomão; Matsuda, Monique; Marquezini, Mônica V; Lima-Silva, Adriano E; Saldiva, Paulo H N; Bertuzzi, Rômulo

2016-05-01

Covering long distances was an important trait to human evolution and continues to be highlighted for health and athletic status. This ability is benefitted by a low cost of locomotion (CoL), meaning that the individuals who are able to expend less energy would be able to cover longer distances. The CoL has been shown to be influenced by distinct and even 'opposite' factors, such as physiological and muscular characteristics, which are genetically inherited. In this way, DNA alterations could be important determinants of the characteristics associated with the CoL. A polymorphism in the ACTN3 gene (R577X) has been related to physical performance, associating the X allele with endurance and the R allele with strength/power abilities. To investigate the influence of ACTN3 genotypes on the CoL. One hundred and fifty healthy male individuals performed two constant speed tests (at 10 and 12 km/h) to determine the CoL. Interestingly, the results showed that heterozygous individuals (RX genotype) presented significantly lower CoL compared to RR and XX individuals. It is argued that RX genotype might generate an intermediate strength-to-endurance phenotype, leading to a better phenotypic profile for energy economy during running and, consequently, for long-term locomotion.

High resolution global climate modelling; the UPSCALE project, a large simulation campaign

NASA Astrophysics Data System (ADS)

Mizielinski, M. S.; Roberts, M. J.; Vidale, P. L.; Schiemann, R.; Demory, M.-E.; Strachan, J.; Edwards, T.; Stephens, A.; Lawrence, B. N.; Pritchard, M.; Chiu, P.; Iwi, A.; Churchill, J.; del Cano Novales, C.; Kettleborough, J.; Roseblade, W.; Selwood, P.; Foster, M.; Glover, M.; Malcolm, A.

2014-01-01

The UPSCALE (UK on PRACE: weather-resolving Simulations of Climate for globAL Environmental risk) project constructed and ran an ensemble of HadGEM3 (Hadley centre Global Environment Model 3) atmosphere-only global climate simulations over the period 1985-2011, at resolutions of N512 (25 km), N216 (60 km) and N96 (130 km) as used in current global weather forecasting, seasonal prediction and climate modelling respectively. Alongside these present climate simulations a parallel ensemble looking at extremes of future climate was run, using a time-slice methodology to consider conditions at the end of this century. These simulations were primarily performed using a 144 million core hour, single year grant of computing time from PRACE (the Partnership for Advanced Computing in Europe) in 2012, with additional resources supplied by the Natural Environmental Research Council (NERC) and the Met Office. Almost 400 terabytes of simulation data were generated on the HERMIT supercomputer at the high performance computing center Stuttgart (HLRS), and transferred to the JASMIN super-data cluster provided by the Science and Technology Facilities Council Centre for Data Archival (STFC CEDA) for analysis and storage. In this paper we describe the implementation of the project, present the technical challenges in terms of optimisation, data output, transfer and storage that such a project involves and include details of the model configuration and the composition of the UPSCALE dataset. This dataset is available for scientific analysis to allow assessment of the value of model resolution in both present and potential future climate conditions.

High-resolution global climate modelling: the UPSCALE project, a large-simulation campaign

NASA Astrophysics Data System (ADS)

Mizielinski, M. S.; Roberts, M. J.; Vidale, P. L.; Schiemann, R.; Demory, M.-E.; Strachan, J.; Edwards, T.; Stephens, A.; Lawrence, B. N.; Pritchard, M.; Chiu, P.; Iwi, A.; Churchill, J.; del Cano Novales, C.; Kettleborough, J.; Roseblade, W.; Selwood, P.; Foster, M.; Glover, M.; Malcolm, A.

2014-08-01

The UPSCALE (UK on PRACE: weather-resolving Simulations of Climate for globAL Environmental risk) project constructed and ran an ensemble of HadGEM3 (Hadley Centre Global Environment Model 3) atmosphere-only global climate simulations over the period 1985-2011, at resolutions of N512 (25 km), N216 (60 km) and N96 (130 km) as used in current global weather forecasting, seasonal prediction and climate modelling respectively. Alongside these present climate simulations a parallel ensemble looking at extremes of future climate was run, using a time-slice methodology to consider conditions at the end of this century. These simulations were primarily performed using a 144 million core hour, single year grant of computing time from PRACE (the Partnership for Advanced Computing in Europe) in 2012, with additional resources supplied by the Natural Environment Research Council (NERC) and the Met Office. Almost 400 terabytes of simulation data were generated on the HERMIT supercomputer at the High Performance Computing Center Stuttgart (HLRS), and transferred to the JASMIN super-data cluster provided by the Science and Technology Facilities Council Centre for Data Archival (STFC CEDA) for analysis and storage. In this paper we describe the implementation of the project, present the technical challenges in terms of optimisation, data output, transfer and storage that such a project involves and include details of the model configuration and the composition of the UPSCALE data set. This data set is available for scientific analysis to allow assessment of the value of model resolution in both present and potential future climate conditions.