Mitchell, T H; Abraham, G; Wing, S; Magder, S A; Cosio, M G; Deschamps, A; Marliss, E B
To determine the effects of neutralizing exercise systemic acidosis via the intravenous route upon endurance and metabolic responses, eight lean, normal, postabsorptive men exercised to exhaustion at about 80% of their VO2 max (69 +/- 3%, mean +/- SEM, of maximum power output) on a cycle ergometer. Exercise studies were performed either with no infusion (control) or with a total infusion volume of about 1.5 L, mainly as 1.3% sodium bicarbonate or as 0.9% sodium chloride (NaCl), infused (double-blind) throughout exercise. The sodium bicarbonate was to prevent acid-base change, the sodium chloride was as a control for the volume infused. Arterialized venous blood and breath-by-breath analysis of expired gases were obtained. [H+] (nmol.L-1) and [HCO3-] (mmol.L-1) at exhaustion were similar in control and NaCl (46.5 +/- 1.8, 19.9 +/- 0.9), but remained unchanged from rest values with bicarbonate (38.4 +/- 0.9, 24.8 +/- 1.5, p less than 0.005 vs control and NaCl). At exhaustion, VO2, VCO2, RER, heart rate, and systolic BP as well as FFA, glycerol, alanine, insulin, norepinephrine, and epinephrine did not differ among protocols. Endurance was markedly prolonged (p less than 0.01) with bicarbonate (31.9 +/- 5.8 min) and NaCl (31.8 +/- 4.1 min) compared with the control (19.0 +/- 2.9 min) condition. Plasma glucose at exhaustion was higher (p less than 0.025) in the control compared to bicarbonate and NaCl experiments, while lactate was higher (p less than 0.025) in the bicarbonate than in the control and NaCl experiments. Thus, the prolonged endurance with sodium bicarbonate infusion could not be explained either by its effect of maintaining blood acid-base equilibrium or concomitant metabolic changes.
Roy, B D; Bosman, M J; Tarnopolsky, M A
This study investigated the possible influence of oral caffeine administration on endogenous glucose production and energy substrate metabolism during prolonged endurance exercise. Twelve trained endurance athletes [seven male, five female; peak oxygen consumption (VO2peak) = 65.5 ml.kg-1.min-1] performed 60 min of cycle ergometry at 65% VO2peak twice, once after oral caffeine administration (6 mg.kg-1) (CAF) and once following consumption of a placebo (PLA). CAF and PLA were administered in a randomized double-blind manner 75 min prior to exercise. Plasma glucose kinetics were determined with a primed-continuous infusion of [6,6-2H]glucose. No differences in oxygen consumption (VO2), and carbon dioxide production (VCO2) were observed between CAF and PLA, at rest or during exercise. Blood glucose concentrations were similar between the two conditions at rest and also during exercise. Exercise did lead to an increase in serum free fatty acid (FFA) concentrations for both conditions; however, no differences were observed between CAF and PLA. Both the plasma glucose rate of appearance (Ra) and disappearance (Rd) increased at the onset of exercise (P < 0.05), but were not affected by CAF, as compared to PLA. CAF did lead to a higher plasma lactate concentration during exercise (P < 0.05). It was concluded that an acute oral dose of caffeine does not influence plasma glucose kinetics or energy substrate oxidation during prolonged exercise in trained endurance athletes. However, CAF did lead to elevated plasma lactate concentrations. The exact mechanism of the increase in plasma lactate concentrations remains to be determined.
Coggan, A R; Spina, R J; Kohrt, W M; Holloszy, J O
It has been hypothesized that endurance training reduces carbohydrate utilization during exercise via citrate-mediated inhibition of phosphofructokinase (PFK). To test this hypothesis, vastus lateralis muscle biopsy samples were obtained from eight men before and immediately (approximately 10 s) after 2 h of cycle ergometer exercise at 60% of pretraining peak O2 uptake, both before and after 12 wk of endurance exercise training (3 days/wk running, 3 days/wk interval cycling). Training increased muscle citrate synthase (CS) activity from 3.69 +/- 0.48 (SE) to 5.30 +/- 0.42 mol.h-1.kg protein-1 and decreased the mean respiratory exchange ratio during exercise from 0.92 +/- 0.01 to 0.88 +/- 0.01 (both P < 0.001). Muscle citrate concentration at the end of exercise correlated significantly with CS activity (r = 0.70; P < 0.005) and was slightly but not significantly higher after training (0.80 +/- 0.19 vs. 0.54 +/- 0.19 mmol/kg dry wt; P = 0.16). Muscle glucose 6-phosphate (G-6-P) concentration at the end of exercise, however, was 31% lower in the trained state (1.17 +/- 0.10 vs. 1.66 +/- 0.27 mmol/kg dry wt; P < 0.05), in keeping with a 36% decrease in the amount of muscle glycogen utilized (133 +/- 22 vs. 209 +/- 19 mmol.kg dry wt-1.2 h-1; P < 0.01). The lower G-6-P concentration after training suggests that the training-induced reduction in carbohydrate utilization results from attenuation of flux before the PFK step in glycolysis and is not due to citrate-mediated inhibition of PFK.
Greenleaf, J. E.; Starr, J. C.; Van Beaumont, W.; Convertino, V. A.
Measurements of maximal grip strength and endurance at 40 percent max strength were obtained for 7 men 19-21 years of age, 1-2 days before and on the first recovery day during three 2-week bedrest (BR) periods, each separated by a 3-week ambulatory recovery period. The subjects performed isometric exercise (IME) for 1 hr/day, isotonic exercise (ITE) for 1 hr/day, and no exercise (NOE) in the three BR periods. It was found that the mean maximal grip strength was unchanged after all three BR periods. Mean grip endurance was found to be unchanged after IME and ITE training, but was significantly reduced after NOE. These results indicate that IME and ITE training during BR do not increase or decrease maximal grip strength, alghough they prevent loss of grip endurance, while the maximal strength of all other major muscle groups decreases in proportion to the length of BR to 70 days. The maximal strength reduction of the large muscle groups was found to be about twice that of the small muscle groups during BR. In addition, it is shown that changes in maximal strength after spaceflight, BR, or water immersion deconditioning cannot be predicted from changes in submaximal or maximal oxygen uptake values.
Gonzalez, Javier T; Fuchs, Cas J; Smith, Fiona E; Thelwall, Pete E; Taylor, Roy; Stevenson, Emma J; Trenell, Michael I; Cermak, Naomi M; van Loon, Luc J C
The purpose of this study was to define the effect of glucose ingestion compared with sucrose ingestion on liver and muscle glycogen depletion during prolonged endurance-type exercise. Fourteen cyclists completed two 3-h bouts of cycling at 50% of peak power output while ingesting either glucose or sucrose at a rate of 1.7 g/min (102 g/h). Four cyclists performed an additional third test for reference in which only water was consumed. We employed (13)C magnetic resonance spectroscopy to determine liver and muscle glycogen concentrations before and after exercise. Expired breath was sampled during exercise to estimate whole body substrate use. After glucose and sucrose ingestion, liver glycogen levels did not show a significant decline after exercise (from 325 ± 168 to 345 ± 205 and 321 ± 177 to 348 ± 170 mmol/l, respectively; P > 0.05), with no differences between treatments. Muscle glycogen concentrations declined (from 101 ± 49 to 60 ± 34 and 114 ± 48 to 67 ± 34 mmol/l, respectively; P < 0.05), with no differences between treatments. Whole body carbohydrate utilization was greater with sucrose (2.03 ± 0.43 g/min) vs. glucose (1.66 ± 0.36 g/min; P < 0.05) ingestion. Both liver (from 454 ± 33 to 283 ± 82 mmol/l; P < 0.05) and muscle (from 111 ± 46 to 67 ± 31 mmol/l; P < 0.01) glycogen concentrations declined during exercise when only water was ingested. Both glucose and sucrose ingestion prevent liver glycogen depletion during prolonged endurance-type exercise. Sucrose ingestion does not preserve liver glycogen concentrations more than glucose ingestion. However, sucrose ingestion does increase whole body carbohydrate utilization compared with glucose ingestion. This trial was registered at https://www.clinicaltrials.gov as NCT02110836.
Scheer, Bernd Volker; Valero-Burgos, Encarna; Costa, Ricardo
This is the first report of a runner with myasthenia gravis who completed an ultra endurance event. Myasthenia gravis, a neuromuscular disease that usually results in skeletal muscle weakness, which worsens with exercise and strenuous aerobic exercise, is generally contraindicated. Our runner completed a 220-km, 5-day ultramarathon and presented with various symptoms including muscular skeletal weakness, cramps, generalized fatigue, unintelligible speech, involuntary eye and mouth movements, problems swallowing, food lodging in his throat, and problems breathing. Risk factors identified for exacerbations are running in extreme temperatures, prolonged runs (especially a distance of 30 km or more), running uphill, lack of sleep, and stress. The medical team was in the novel situation to look after a runner with myasthenia gravis and needed to be aware of the patient's condition, symptoms, and risk factors to safely care for him.
Acute changes in endocrine and fluid balance markers during high-intensity, steady-state, and prolonged endurance running: unexpected increases in oxytocin and brain natriuretic peptide during exercise.
Hew-Butler, Tamara; Noakes, Timothy D; Soldin, Steven J; Verbalis, Joseph G
Maintenance of fluid homeostasis during periods of heightened physical stress can be best evaluated in humans using exercise as a model. Although it is well established that arginine vasopressin (AVP), aldosterone and atrial natriuretic peptide (ANP) are the principle hormones regulating fluid balance at rest, the potential contributions of other related endocrine factors, such as oxytocin (OT) and brain natriuretic peptide (BNP), have not been well described during exercise. Seven endurance-trained runners completed three separate running trials: a maximal test to exhaustion (high intensity), a 60-min treadmill run (steady state), and a 56 km ultramarathon (prolonged endurance exercise). Statistically significant pre- to post-run increases were found only following the ultramarathon in [AVP](p) (1.9 vs 6.7 pg/ml; P<0.05), [OT](p) (1.5 vs 3.5 pg/ml; P<0.05), [NT-proBNP](p) (23.6 vs 117.9 pg/ml; P<0.01), [interleukin 6](p) (4.0 vs 59.6 pg/ml; P<0.05), [cortisol](p) (14.6 vs 32.6 microg/ml; P<0.01), [corticosterone](p) (652.8 vs 3491.4 ng/ml; P<0.05) and [11-deoxycortisol](p) (0.1 vs 0.5 microg/ml; P<0.05) while a significant post-run increase in [aldosterone](p) was documented after high-intensity (4.9 vs 12.5 ng/ml; P<0.05), steady-state (6.1 vs 16.9 ng/ml; P<0.05) and prolonged endurance running (2.6 vs 19.7 ng/ml; P<0.05). Similarly, changes in fluid balance parameters were significantly different between the ultramarathon versus high-intensity and steady-state running with regard to plasma volume contraction (less % contraction), body weight loss (increased % weight loss), plasma [Na(+)] Delta (decreased from baseline), and urine osmolality Delta (increase from baseline). Hypothetically driven relationships between [OT](p) and [AVP](p) (r=0.69; P<0.01) and between [NT-proBNP](p) Delta and plasma [Na(+)] Delta (r=-0.79; P<0.001)--combined with the significant and unexpected pre- to post-race increases after prolonged endurance exercise--allows for possible
Noakes, Timothy David
A skeletal design which favours running and walking, including the greatest ratio of leg length to body weight of any mammal; the ability to sweat and so to exercise vigorously in the heat; and greater endurance than all land mammals other than the Alaskan Husky, indicates that humans evolved as endurance animals. The development of tools to accurately measure time and distance in the nineteenth century inspired some humans to define the limits of this special capacity. Beginning with Six-Day Professional Pedestrian Races in London and New York in the 1880s, followed a decade later by Six-Day Professional Cycling Races - the immediate precursor of the first six-day Tour de France Cycliste race in 1903, which itself inspired the 1928 and 1929 4,960 km "Bunion Derbies" between Los Angeles and New York across the breadth of the United States of America - established those unique sporting events that continue to challenge the modern limits of human endurance. But an analysis of the total energy expenditure achieved by athletes competing in those events establishes that none approaches those reached by another group - the explorers of the heroic age of polar exploration in the early twentieth century. Thus the greatest recorded human endurance performances occurred during the Antarctic sledding expeditions led by Robert Scott in 1911/12 and Ernest Shackleton in 1914/16. By man-hauling sleds for 10 hours daily for approximately 159 and 160 consecutive days respectively, members of those expeditions would have expended close to a total of 1,000,000 kcal. By comparison completing a Six-Day Pedestrian event (55,000 kcal) or the Tour de France (168,000 kcal), or cycling (180,000 kcal) or running (340,000 kcal) across America, requires a considerably smaller total energy expenditure. Thus the limits of human endurance were set at the start of the twentieth century and have not recently been approached. Given good health and an adequate food supply to prevent starvation and
Montner, P.; Stark, D. M.; Riedesel, M. L.; Murata, G.; Robergs, R.; Timms, M.; Chick, T. W.
The effects of glycerol ingestion (GEH) on hydration and subsequent cycle ergometer submaximal load exercise were examined in well conditioned subjects. We hypothesized that GEH would reduce physiologic strain and increase endurance. The purpose of Study I (n = 11) was to determine if pre-exercise GEH (1.2 gm/kg glycerol in 26 ml/kg solution) compared to pre-exercise placebo hydration (PH) (26 ml/kg of aspartame flavored water) lowered heart rate (HR), lowered rectal temperature (Tc), and prolonged endurance time (ET) during submaximal load cycle ergometry. The purpose of Study II (n = 7) was to determine if the same pre-exercise regimen followed by carbohydrate oral replacement solution (ORS) during exercise also lowered HR, Tc, and prolonged ET. Both studies were double-blind, randomized, crossover trials, performed at an ambient temperature of 23.5-24.5 degrees C, and humidity of 25-27%. Mean HR was lower by 2.8 +/- 0.4 beats/min (p = 0.05) after GEH in Study I and by 4.4 +/- 1.1 beats/min (p = 0.01) in Study II. Endurance time was prolonged after GEH in Study I (93.8 +/- 14 min vs. 77.4 +/- 9 min, p = 0.049) and in Study II (123.4 +/- 17 min vs. 99.0 +/- 11 min, p = 0.03). Rectal temperature did not differ between hydration regimens in both Study I and Study II. Thus, pre-exercise glycerol-enhanced hyperhydration lowers HR and prolongs ET even when combined with ORS during exercise. The regimens tested in this study could potentially be adapted for endurance activities.
Lim, Kiwon; Ryu, Sungpil; Suh, Heajung; Ishihara, Kengo; Fushiki, Tohru
We have been interested in the ergogenic aid effects of food components and supplements for enhancing endurance exercise performance. For this purpose, acute or chronic (-)-hydroxycitrate (HCA) ingestion might be effective because it promotes utilization of fatty acid as an energy source. HCA is a competitive inhibitor of the enzyme ATP: citrate lyase, thereby increasing inhibition of lipogenesis in the body. Many researchers have reported that less body fat accumulation and sustained satiety cause less food intake. After focusing on exercise performance with HCA ingestion, we came up with different results that show positive effects or not. However, our previously reported data showed increased use of fatty acids during moderate intensity exercise. For future research, HCA and co-ingestion of other supplements, such as carnitine or caffeine, might have greater effect on glycogen-sparing than HCA alone.
Arnaud, S.; Berry, P; Cohen, M.; Danelis, J.; Deroshia, C.; Greenleaf, J.; Harris, B.; Keil, L.; Bernauer, E.; Bond, M.; Ellis, S.; Lee, P.; Selzer, R.; Wade, C.
Report describes experiment to investigate effects of isotonic and isokinetic leg exercises in counteracting effects of bed rest upon physical and mental conditions of subjects. Data taken on capacity for work, endurance and strength, tolerance to sitting up, equilibrium, posture, gait, atrophy, mineralization and density of bones, endocrine analyses concerning vasoactivity and fluid and electrolyte balances, intermediary metabolism of muscles, mood, and performance.
Kim, Hyeon-Ki; Ando, Karina; Tabata, Hiroki; Konishi, Masayuki; Takahashi, Masaki; Nishimaki, Mio; Xiang, Mi; Sakamoto, Shizuo
To study the effects of different exercise intensity performed at different exercise times on lipid metabolism response during prolonged exercise. Nine young men performed endurance exercise at different exercise intensities (60%VO2max or Fatmax) in the morning (9 am to 10 am) or evening (5 pm to 6 pm); blood samples were collected before exercise and immediately and one and two hours after exercise completion. Expired gas was analyzed from the start of exercise until two hours after exercise completion. There were no significant changes in catecholamine (adrenaline and noradrenaline) and free fatty acid levels between morning and evening trials for each endurance exercise intensity. However, the morning and evening trials both exhibited significantly higher lipid oxidation at Fatmax than that at 60%VO2max. These results suggest that exercise at Fatmax offers greater lipid oxidation than that at 60%VO2max, regardless of exercise timing. Key points It is important to consider exercise intensity when evaluating lipid oxidation. Few studies have investigated the effects of the intensity of exercise on lipid oxidation in the morning and evening. Fatmax exhibited greater total lipid oxidation compared to that of 60%VO2max when energy expenditure was equated, but time of day did not affect lipid oxidation in prolonged exercise. PMID:27803625
Martin, B J
Acute loss of sleep produces few apparent physiological effects at rest. Nevertheless, many anecdotes suggest that adequate sleep is essential for optimum endurance athletic performance. To investigate this question, heavy exercise performance after 36 h without sleep was compared with that after normal sleep in eight subjects. During prolonged treadmill walking at about 80% of the VO2 max, sleep loss reduced work time to exhaustion by an average of 11% (p = 0.05). This decrease occurred despite doubling monetary incentives for subjects during work after sleeplessness. Subjects appeared to fall into "resistant" and "susceptible" categories: four showed less than a 5% change in performance after sleep loss, while four others showed decrements in exercise tolerance ranging from 15 to 40%. During the walk, sleep loss resulted in significantly greater perceived exertion (p less than 0.05), even though exercise heart rate and metabolic rate (VO2 and VCO2) were unchanged. Minute ventilation was significantly elevated during exercise after sleep loss ( p less than 0.05). Sleep loss failed to alter the continuous slow rises in VE and heart rate that occurred as work was prolonged. These findings suggest that the psychological effects of acute sleep loss may contribute to decreased tolerance of prolonged heavy exercise.
Trottier, N L; Nielsen, B D; Lang, K J; Ku, P K; Schott, H C
Six 2-year-old Arabian horses were used to determine whether 60 km prolonged endurance exercise (approximately 4 h) alters amino acid concentrations in serum and muscle, and the time required for serum amino acid concentrations to return to basal resting values. Blood and muscle samples were collected throughout exercise and during a 3 day recovery period. Isoleucine concentration in muscle tended to increase and leucine and valine did not change due to exercise. Serum alanine concentrations did not increase immediately after exercise, but increased at 24, 48 and 72 h postexercise. Serum isoleucine, leucine, and valine concentrations decreased after exercise and time required to reach pre-exercising concentrations was 48 h. In conclusion, endurance exercise in the horse decreases serum isoleucine, leucine, and valine concentrations, and increases serum alanine concentration. The decrease in serum branched-chain amino acid concentrations did not correspond to a measurable increase in total muscle branched-chain amino acid concentrations.
Raven, P. B.
Astronauts are often required to work (exercise) at moderate to high intensities for extended periods while performing extra-vehicular activities (EVA). Although the physiologic responses associated with prolonged exercise have been documented, the mechanisms involved in blood pressure regulation under these conditions have not yet been fully elucidated. An understanding of this issue is pertinent to the ability of humans to perform work in microgravity and complies with the emphasis of NASA's Space Physiology and Countermeasures Program. Prolonged exercise at a constant workload is know to result in a progressive decrease in mean arterial pressure (MAP) concomitant with a decrease in stroke volume and a compensatory increase in heart rate. The continuous decrease in MAP during the exercise, which is related to the thermoregulatory redistribution of circulating blood volume to the cutaneous circulation, raises the question as to whether there is a loss of baroreflex regulation of arterial blood pressure. We propose that with prolongation of the exercise to 60 minutes, progressive increases on central command reflect a progressive upward resetting of the carotid baroreflex (CBR) such that the operating point of the CBR is shifted to a pressure below the threshold of the reflex rendering it ineffectual in correcting the downward drift in MAP. In order to test this hypothesis, experiments have been designed to uncouple the global hemodynamic response to prolonged exercise from the central command mediated response via: (1) continuous maintenance of cardiac filling volume by intravenous infusion of a dextran solution; and (2) whole body surface cooling to counteract thermoregulatory cutaneous vasodialation. As the type of work (exercise) performed by astronauts is inherently arm and upper body dependent, we will also examine the physiologic responses to prolonged leg cycling and arm ergometry exercise in the supine positions with and without level lower body negative
Eijsvogels, Thijs M H; Fernandez, Antonio B; Thompson, Paul D
Multiple epidemiological studies document that habitual physical activity reduces the risk of atherosclerotic cardiovascular disease (ASCVD), and most demonstrate progressively lower rates of ASCVD with progressively more physical activity. Few studies have included individuals performing high-intensity, lifelong endurance exercise, however, and recent reports suggest that prodigious amounts of exercise may increase markers for, and even the incidence of, cardiovascular disease. This review examines the evidence that extremes of endurance exercise may increase cardiovascular disease risk by reviewing the causes and incidence of exercise-related cardiac events, and the acute effects of exercise on cardiovascular function, the effect of exercise on cardiac biomarkers, including "myocardial" creatine kinase, cardiac troponins, and cardiac natriuretic peptides. This review also examines the effect of exercise on coronary atherosclerosis and calcification, the frequency of atrial fibrillation in aging athletes, and the possibility that exercise may be deleterious in individuals genetically predisposed to such cardiac abnormalities as long QT syndrome, right ventricular cardiomyopathy, and hypertrophic cardiomyopathy. This review is to our knowledge unique because it addresses all known potentially adverse cardiovascular effects of endurance exercise. The best evidence remains that physical activity and exercise training benefit the population, but it is possible that prolonged exercise and exercise training can adversely affect cardiac function in some individuals. This hypothesis warrants further examination.
Eijsvogels, Thijs M. H.; Fernandez, Antonio B.; Thompson, Paul D.
Multiple epidemiological studies document that habitual physical activity reduces the risk of atherosclerotic cardiovascular disease (ASCVD), and most demonstrate progressively lower rates of ASCVD with progressively more physical activity. Few studies have included individuals performing high-intensity, lifelong endurance exercise, however, and recent reports suggest that prodigious amounts of exercise may increase markers for, and even the incidence of, cardiovascular disease. This review examines the evidence that extremes of endurance exercise may increase cardiovascular disease risk by reviewing the causes and incidence of exercise-related cardiac events, and the acute effects of exercise on cardiovascular function, the effect of exercise on cardiac biomarkers, including “myocardial” creatine kinase, cardiac troponins, and cardiac natriuretic peptides. This review also examines the effect of exercise on coronary atherosclerosis and calcification, the frequency of atrial fibrillation in aging athletes, and the possibility that exercise may be deleterious in individuals genetically predisposed to such cardiac abnormalities as long QT syndrome, right ventricular cardiomyopathy, and hypertrophic cardiomyopathy. This review is to our knowledge unique because it addresses all known potentially adverse cardiovascular effects of endurance exercise. The best evidence remains that physical activity and exercise training benefit the population, but it is possible that prolonged exercise and exercise training can adversely affect cardiac function in some individuals. This hypothesis warrants further examination. PMID:26607287
temperature threshold for initiation of eccrine sweating and cutaneous vasodilation during exercise (15,15,17). It has also been suggested, in two widely...Local control of eccrine sweat gland function. Fed. Proc. 32:1583-1587, 1983. 4. Piorica, V., B.A. Higgins, P.F. lampietro, M.T. Lategola and A.W...reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP cutaneous blood flow, sleep loss, sweating , wakefulness 19. ABSTRACT (Continue on
Mora-Rodríguez, R; Fernández-Elías, V E; Hamouti, N; Ortega, J F
We studied if dehydrating exercise would reduce muscle water (H2Omuscle ) and affect muscle electrolyte concentrations. Vastus lateralis muscle biopsies were collected prior, immediately after, and 1 and 4 h after prolonged dehydrating exercise (150 min at 33 ± 1 °C, 25% ± 2% humidity) on nine endurance-trained cyclists (VO2max = 54.4 ± 1.05 mL/kg/min). Plasma volume (PV) changes and fluid shifts between compartments (Cl(-) method) were measured. Exercise dehydrated subjects 4.7% ± 0.3% of body mass by losing 2.75 ± 0.15 L of water and reducing PV 18.4% ± 1% below pre-exercise values (P < 0.05). Right after exercise H2Omuscle remained at pre-exercise values (i.e., 398 ± 6 mL/100 g dw muscle(-1)) but declined 13% ± 2% (342 ± 12 mL/100 g dw muscle(-1); P < 0.05) after 1 h of supine rest. At that time, PV recovered toward pre-exercise levels. The Cl(-) method corroborated the shift of fluid between extracellular and intracellular compartments. After 4 h of recovery, PV returned to pre-exercise values; however, H2Omuscle remained reduced at the same level. Muscle Na(+) and K(+) increased (P < 0.05) in response to the H2Omuscle reductions. Our findings suggest that active skeletal muscle does not show a net loss of H2O during prolonged dehydrating exercise. However, during the first hour of recovery H2Omuscle decreases seemly to restore PV and thus cardiovascular stability.
Aschar-Sobbi, Roozbeh; Izaddoustdar, Farzad; Korogyi, Adam S.; Wang, Qiongling; Farman, Gerrie P.; Yang, FengHua; Yang, Wallace; Dorian, David; Simpson, Jeremy A.; Tuomi, Jari M.; Jones, Douglas L.; Nanthakumar, Kumaraswamy; Cox, Brian; Wehrens, Xander H.T.; Dorian, Paul; Backx, Peter H.
Atrial fibrillation (AF) is the most common supraventricular arrhythmia that, for unknown reasons, is linked to intense endurance exercise. Our studies reveal that 6 weeks of swimming or treadmill exercise improves heart pump function and reduces heart-rates. Exercise also increases vulnerability to AF in association with inflammation, fibrosis, increased vagal tone, slowed conduction velocity, prolonged cardiomyocyte action potentials and RyR2 phosphorylation (CamKII-dependent S2814) in the atria, without corresponding alterations in the ventricles. Microarray results suggest the involvement of the inflammatory cytokine, TNFα, in exercised-induced atrial remodelling. Accordingly, exercise induces TNFα-dependent activation of both NFκB and p38MAPK, while TNFα inhibition (with etanercept), TNFα gene ablation, or p38 inhibition, prevents atrial structural remodelling and AF vulnerability in response to exercise, without affecting the beneficial physiological changes. Our results identify TNFα as a key factor in the pathology of intense exercise-induced AF. PMID:25598495
Graham, T E
Caffeine is a common substance in the diets of most athletes and it is now appearing in many new products, including energy drinks, sport gels, alcoholic beverages and diet aids. It can be a powerful ergogenic aid at levels that are considerably lower than the acceptable limit of the International Olympic Committee and could be beneficial in training and in competition. Caffeine does not improve maximal oxygen capacity directly, but could permit the athlete to train at a greater power output and/or to train longer. It has also been shown to increase speed and/or power output in simulated race conditions. These effects have been found in activities that last as little as 60 seconds or as long as 2 hours. There is less information about the effects of caffeine on strength; however, recent work suggests no effect on maximal ability, but enhanced endurance or resistance to fatigue. There is no evidence that caffeine ingestion before exercise leads to dehydration, ion imbalance, or any other adverse effects. The ingestion of caffeine as coffee appears to be ineffective compared to doping with pure caffeine. Related compounds such as theophylline are also potent ergogenic aids. Caffeine may act synergistically with other drugs including ephedrine and anti-inflammatory agents. It appears that male and female athletes have similar caffeine pharmacokinetics, i.e., for a given dose of caffeine, the time course and absolute plasma concentrations of caffeine and its metabolites are the same. In addition, exercise or dehydration does not affect caffeine pharmacokinetics. The limited information available suggests that caffeine non-users and users respond similarly and that withdrawal from caffeine may not be important. The mechanism(s) by which caffeine elicits its ergogenic effects are unknown, but the popular theory that it enhances fat oxidation and spares muscle glycogen has very little support and is an incomplete explanation at best. Caffeine may work, in part, by
Tanaka, D; Suga, T; Tanaka, T; Kido, K; Honjo, T; Fujita, S; Hamaoka, T; Isaka, T
Ischemic preconditioning (IPC) enhances whole-body exercise endurance. However, it is poorly understood whether the beneficial effects originate from systemic (e. g., cardiovascular system) or peripheral (e. g., skeletal muscle) adaptations. The present study examined the effects of IPC on local muscle endurance during fatiguing isometric exercise. 12 male subjects performed sustained isometric unilateral knee-extension exercise at 20% of maximal voluntary contraction until failure. Prior to the exercise, subjects completed IPC or control (CON) treatments. During exercise trial, electromyography activity and near-infrared spectroscopy-derived deoxygenation in skeletal muscle were continuously recorded. Endurance time to task failure was significantly longer in IPC than in CON (mean±SE; 233±9 vs. 198±9 s, P<0.001). Quadriceps electromyography activity was not significantly different between IPC and CON. In contrast, deoxygenation dynamics in the quadriceps vastus lateralis muscle was significantly faster in IPC than in CON (27.1±3.4 vs. 35.0±3.6 s, P<0.01). The present study found that IPC can enhance muscular endurance during fatiguing isometric exercise. Moreover, IPC accelerated muscle deoxygenation dynamics during the exercise. Therefore, we suggest that the origin of beneficial effects of IPC on exercise performance may be the enhanced mitochondrial metabolism in skeletal muscle.
Conceição, Matheus; Cadore, Eduardo Lusa; González-Izal, Miriam; Izquierdo, Mikel; Liedtke, Giane Veiga; Wilhelm, Eurico Nestor; Pinto, Ronei Silveira; Goltz, Fernanda Reistenbach; Schneider, Cláudia Dornelles; Ferrari, Rodrigo; Bottaro, Martim; Kruel, Luiz Fernando Martins
This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise.
Patil, Harshal R; O'Keefe, James H; Lavie, Carl J; Magalski, Anthony; Vogel, Robert A; McCullough, Peter A
A daily routine of physical activity is highly beneficial in the prevention and treatment of many prevalent chronic diseases, especially of the cardiovascular (CV) system. However, chronic, excessive sustained endurance exercise may cause adverse structural remodeling of the heart and large arteries. An evolving body of data indicates that chronically training for and participating in extreme endurance competitions such as marathons, ultra-marathons, Iron-man distance triathlons, very long distance bicycle racing, etc., can cause transient acute volume overload of the atria and right ventricle, with transient reductions in right ventricular ejection fraction and elevations of cardiac biomarkers, all of which generally return to normal within seven to ten days. In veteran extreme endurance athletes, this recurrent myocardial injury and repair may eventually result in patchy myocardial fibrosis, particularly in the atria, interventricular septum and right ventricle, potentially creating a substrate for atrial and ventricular arrhythmias. Furthermore, chronic, excessive, sustained, high-intensity endurance exercise may be associated with diastolic dysfunction, large-artery wall stiffening and coronary artery calcification. Not all veteran extreme endurance athletes develop pathological remodeling, and indeed lifelong exercisers generally have low mortality rates and excellent functional capacity. The aim of this review is to discuss the emerging understanding of the cardiac pathophysiology of extreme endurance exercise, and make suggestions about healthier fitness patterns for promoting optimal CV health and longevity.
Lamon, Séverine; Wallace, Marita A; Stefanetti, Renae J; Rahbek, Stine K; Vendelbo, Mikkel H; Russell, Aaron P; Vissing, Kristian
The striated muscle activator of Rho signaling (STARS) protein and members of its downstream signaling pathway, including myocardin-related transcription factor-A (MRTF-A) and SRF, are increased in response to prolonged resistance exercise training but also following a single bout of endurance cycling. The aim of the present study was to measure and compare the regulation of STARS, MRTF-A and SRF mRNA and protein following 10 weeks of endurance training (ET) versus resistance training (RT), as well as before and following a single bout of endurance (EE) versus resistance exercise (RE). Following prolonged training, STARS, MRTF-A and SRF mRNA levels were all increased by similar magnitude, irrespective of training type. In the training-habituated state, STARS mRNA increased following a single-bout RE when measured 2.5 and 5 h post-exercise and had returned to resting level by 22 h following exercise. MRTF-A and SRF mRNA levels were decreased by 2.5, 5, and 22 h following a single bout of RE and EE exercise when compared to their respective basal levels, with no significant difference seen between the groups at any of the time points. No changes in protein levels were observed following the two modes of exercise training or a single bout of exercise. This study demonstrates that the stress signals elicited by ET and RT result in a comparable regulation of members of the STARS pathway. In contrast, a single bout of EE and RE, performed in the trained state, elicit different responses. These observations suggest that in the trained state, the acute regulation of the STARS pathway following EE or RE may be responsible for exercise-specific muscle adaptations.
Roberts, William O.
Describes a classification system devised for exercise-associated collapse in endurance events based on casualties observed at six Twin Cities Marathons. Major diagnostic criteria are body temperature and mental status. Management protocol includes fluid and fuel replacement, temperature correction, and leg cramp treatment. (Author/SM)
This study examined alterations in skeletal-muscle growth and atrophy-related molecular events after a single bout of moderate-intensity endurance exercise. Muscle biopsies were obtained from 10 men (23 +/- 1 yr, body mass 80 +/- 2 kg, and VO(2peak) 45 +/- 1 ml x kg'¹ x min'¹) immediately (0 hr) and...
BURNHAM, STAN; MCCRAW, LYNN W.
A STUDY WAS CONCERNED WITH A COMPARISON OF ISOTONIC, ISOMETRIC, AND SPEED EXERCISE PROGRAMS AS A MEANS OF DEVELOPING MUSCLE STRENGTH, ENDURANCE, SPEED, AND POWER. SUBJECTS FOR THE INVESTIGATION WERE 93 FRESHMEN AND SOPHOMORE MEN ENROLLED IN A PHYSICAL EDUCATION CLASS. AFTER MEASUREMENT OF INITIAL STATUS IN THE ATTRIBUTES UNDER CONSIDERATION, THE…
Manier, G; Moinard, J; Téchoueyres, P; Varène, N; Guénard, H
To determine the effect of strenuous prolonged exercise on alveolo-capillary membrane diffusing capacity, 11 marathon runners aged 37 +/- 7 years (mean +/- SD) were studied before and during early recovery (28 +/- 14 min) from a marathon race. Lung capillary blood volume (Vc) and the alveolo-capillary diffusing capacity (Dm) were determined in a one-step maneuver by simultaneous measurements of CO and NO lung transfer (DLCO and DLNO, respectively) using the single breath, breath-holding method. After the race, both DLCO and DLNO were significantly decreased in all subjects (-10.9 +/- 4.8%, P less than 10(-4) and -29.0 +/- 11.1%, P less than 10(-4), respectively). The mean value of the derived DmCO decreased by -29.3 +/- 11.1%, whereas Vc had not entirely returned to control resting value. Although these results do not indicate the detailed mechanism involved, interstitial lung fluid was suspected to accumulate, particularly in alveoli, during the race. We concluded that the high overall work load and the extended duration of the exercise both contributed to a transient change in the structure of the alveolo-capillary membrane thereby affecting the diffusing capacity of the alveolo-capillary membrane.
Joyner, Michael J; Coyle, Edward F
Efforts to understand human physiology through the study of champion athletes and record performances have been ongoing for about a century. For endurance sports three main factors – maximal oxygen consumption , the so-called ‘lactate threshold’ and efficiency (i.e. the oxygen cost to generate a give running speed or cycling power output) – appear to play key roles in endurance performance. and lactate threshold interact to determine the ‘performance ‘ which is the oxygen consumption that can be sustained for a given period of time. Efficiency interacts with the performance to establish the speed or power that can be generated at this oxygen consumption. This review focuses on what is currently known about how these factors interact, their utility as predictors of elite performance, and areas where there is relatively less information to guide current thinking. In this context, definitive ideas about the physiological determinants of running and cycling efficiency is relatively lacking in comparison with and the lactate threshold, and there is surprisingly limited and clear information about the genetic factors that might pre-dispose for elite performance. It should also be cautioned that complex motivational and sociological factors also play important roles in who does or does not become a champion and these factors go far beyond simple physiological explanations. Therefore, the performance of elite athletes is likely to defy the types of easy explanations sought by scientific reductionism and remain an important puzzle for those interested in physiological integration well into the future. PMID:17901124
Perret, C; Pfeiffer, R; Boutellier, U; Wey, H M; Spengler, C M
The use of noninvasive techniques to measure respiratory muscle performance after different types of endurance exercise has not been entirely successful, as the results have not consistently indicated diminished performance for similar types of exercise. The aim of the present study was 1) to compare different, noninvasive methods to assess respiratory muscle performance before and after an exhaustive cycling endurance test (which has previously been shown to induce diaphragmatic fatigue) and 2) to determine which of the tests best reflect published results of measurements of diaphragmatic fatigue. Twelve healthy subjects participated in the study and performed three different test series in a random order on three different days. These tests were performed before, and 5, 40 and 75 min after an exhausting task (a cycling endurance run at 85% of maximal oxygen uptake (V'O2,max)). The tests of the three test series were 1) breathing against a constant inspiratory resistance to task failure, 2) determination of 12-min sustained ventilatory capacity, and 3) spirometric and maximal inspiratory and expiratory mouth pressure measurements. The only measurement that was affected by exhaustive cycling was the time to task failure breathing against inspiratory resistance. It was significantly reduced from (mean+/-sD) 364+/-88 s before exercise to 219+/-122 s at 5 min after cessation of exercise. It is concluded that the constant-load resistive breathing test to task failure is the only noninvasive respiratory muscle performance test evaluated in this study which shows a decrease in respiratory muscle performance after exhaustive endurance exercise.
Gardner, A W; Poehlman, E T; Corrigan, D L
We compared the effect of endurance exercise training on gross energy expenditure (GEE) during steady-state exercise in 20 younger men (31.2 +/- 0.6 years) and 20 middle-aged men (49.2 +/- 1.1 years). The subjects trained for eight months. The training program consisted of three 45-min walking and jogging exercise sessions per week at an intensity of approximately 60-85% of the heart rate at peak VO2. We administered bicycle ergometer tests at 0, 4, and 8 months into training. Participants exercised at a power output of 100 W for 10 min using a pedaling frequency of 50 rpm. We determined GEE (kcal/min) by measuring the oxygen consumption and respiratory exchange ratio. We found a significant reduction (p less than 0.05) in GEE (0.7-1.3 kcal/min) following 4 months of endurance training in both age groups, with a further reduction (p less than 0.05) noted in only the middle-aged group at month 8. We found no difference (p greater than 0.05) in GEE between the younger and middle-aged men. We conclude that chronic exercise may modify GEE during a submaximal exercise bout and that this adaptation is similar in magnitude in younger and middle-aged men.
Skovgaard, Casper; Brandt, Nina; Pilegaard, Henriette; Bangsbo, Jens
The aim of this study was to investigate the mRNA response related to mitochondrial biogenesis, metabolism, angiogenesis, and myogenesis in trained human skeletal muscle to speed endurance exercise (S), endurance exercise (E), and speed endurance followed by endurance exercise (S + E). Seventeen trained male subjects (maximum oxygen uptake (VO2-max): 57.2 ± 3.7 (mean ± SD) mL·min(-1)·kg(-1)) performed S (6 × 30 sec all-out), E (60 min ~60% VO2-max), and S + E on a cycle ergometer on separate occasions. Muscle biopsies were obtained at rest and 1, 2, and 3 h after the speed endurance exercise (S and S + E) and at rest, 0, 1, and 2 h after exercise in E In S and S + E, muscle peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1α) and pyruvate dehydrogenase kinase-4 (PDK4) mRNA were higher (P < 0.05) 2 and 3 h after speed endurance exercise than at rest. Muscle PGC-1α and PDK4 mRNA levels were higher (P < 0.05) after exercise in S + E than in S and E, and higher (P < 0.05) in S than in E after exercise. In S and S + E, muscle vascular endothelial growth factor mRNA was higher (P < 0.05) 1 (S only), 2 and 3 h after speed endurance exercise than at rest. In S + E, muscle regulatory factor-4 and muscle heme oxygenase-1 mRNA were higher (P < 0.05) 1, 2, and 3 h after speed endurance exercise than at rest. In S, muscle hexokinase II mRNA was higher (P < 0.05) 2 and 3 h after speed endurance exercise than at rest and higher (P < 0.05) than in E after exercise. These findings suggest that in trained subjects, speed endurance exercise provides a stimulus for muscle mitochondrial biogenesis, substrate regulation, and angiogenesis that is not evident with endurance exercise. These responses are reinforced when speed endurance exercise is followed by endurance exercise.
... carry out many of your everyday activities. Brisk walking or jogging Yard work (mowing, raking, digging) Dancing ... hills Playing tennis Playing basketball Sample Endurance Exercise: Walking How Much, How Often Build up your endurance ...
Kakanis, Michael W; Peake, Jonathan; Brenu, Ekua W; Simmonds, Michael; Gray, Bon; Marshall-Gradisnik, Sonya M
Endurance exercise can cause immunosuppression and increase the risk of upper respiratory illness. The present study examined changes in the secretion of T helper (Th) cell cytokines after endurance exercise. Ten highly trained road cyclists [mean±SEM: age 24.2±1.7 years; height 1.82±0.02 m; body mass 73.8±2.0 kg; peak oxygen uptake 65.9±2.3 mL/(kg•min)] performed 2 h of cycling exercise at 90% of the second ventilatory threshold. Peripheral blood mononuclear cells were isolated and stimulated with phytohemagglutinin. Plasma cortisol concentrations and the concentration of Th1/Th2/Th17 cell cytokines were examined. Data were analyzed using both traditional statistics and magnitude-based inferences. Results revealed a significant decrease in plasma cortisol at 4-24 h postexercise compared with pre-exercise values. Qualitative analysis revealed postexercise changes in concentrations of plasma cortisol, IL-2, TNF, IL-4, IL-6, IL-10, and IL-17A compared with pre-exercise values. A Th1/Th2 shift was evident immediately postexercise. Furthermore, for multiple cytokines, including IL-2 and TNF (Th1), IL-6 and IL-10 (Th2), and IL-17 (Th17), no meaningful change in concentration occurred until more than 4 h postexercise, highlighting the duration of exercise-induced changes in immune function. These results demonstrate the importance of considering "clinically" significant versus statistically significant changes in immune cell function after exercise.
Bonetti, A; Tirelli, F; Albertini, R; Monica, C; Monica, M; Tredici, G
Recently Dr. Rowe made a hypothesis according to which small areas of myocardial necrosis can be caused by microvascular spasm, related to high catecholamine concentrations and other mechanisms, following extraordinary unremitting endurance exercises or due to the cumulative effect of several endurance events. It was this last suggestion which prompted us to investigate 25 top cyclists, taking part in the 77th Giro d'Italia. Blood samples were obtained the day before the start of the competition and once a week thereafter until the end. We measured myoglobin, lactic dehydrogenase, total creatine kinase, creatine kinase isoenzyme MB and serum cardiac troponin T (Tn-T), a highly sensitive and specific method for the detection of myocardial injury. While at measuring time points which followed we found a significant increase in the serum indicators of muscle damage, compared with their values at the beginning of the race, creatine kinase isoenzyme MB did not rise significantly and cardiac Tn-T was found in the serum of only 5 athletes, repeatedly in some cases, but always below the cut off values considered as indicating myocardial ischemia. On the basis of the behaviour of creatine kinase isoenzyme MB and, above all, of cardiac Tn-T, we can conclude that heavy endurance exercises, repeated daily for 22 days, as was the case in our study, do not seem able to produce, in top athletes, permanent heart damage by means of acute myocardial injury.
Burniston, Jatin G.; Kavazis, Andreas N.; Morton, Aaron B.; Wiggs, Michael P.; Ahn, Bumsoo; Smuder, Ashley J.; Powers, Scott K.
Mechanical ventilation (MV) is a life-saving intervention for many critically ill patients. Unfortunately, prolonged MV results in the rapid development of diaphragmatic atrophy and weakness. Importantly, endurance exercise training results in a diaphragmatic phenotype that is protected against ventilator-induced diaphragmatic atrophy and weakness. The mechanisms responsible for this exercise-induced protection against ventilator-induced diaphragmatic atrophy remain unknown. Therefore, to investigate exercise-induced changes in diaphragm muscle proteins, we compared the diaphragmatic proteome from sedentary and exercise-trained rats. Specifically, using label-free liquid chromatography-mass spectrometry, we performed a proteomics analysis of both soluble proteins and mitochondrial proteins isolated from diaphragm muscle. The total number of diaphragm proteins profiled in the soluble protein fraction and mitochondrial protein fraction were 813 and 732, respectively. Endurance exercise training significantly (P<0.05, FDR <10%) altered the abundance of 70 proteins in the soluble diaphragm proteome and 25 proteins of the mitochondrial proteome. In particular, key cytoprotective proteins that increased in relative abundance following exercise training included mitochondrial fission process 1 (Mtfp1; MTP18), 3-mercaptopyruvate sulfurtransferase (3MPST), microsomal glutathione S-transferase 3 (Mgst3; GST-III), and heat shock protein 70 kDa protein 1A/1B (HSP70). While these proteins are known to be cytoprotective in several cell types, the cyto-protective roles of these proteins have yet to be fully elucidated in diaphragm muscle fibers. Based upon these important findings, future experiments can now determine which of these diaphragmatic proteins are sufficient and/or required to promote exercise-induced protection against inactivity-induced muscle atrophy. PMID:28135290
Waddington, Gordon; Keegan, Richard J.; Thompson, Kevin G.; Cathcart, Stuart
Background The ergogenic effects of analgesic substances suggest that pain perception is an important regulator of work-rate during fatiguing exercise. Recent research has shown that endogenous inhibitory responses, which act to attenuate nociceptive input and reduce perceived pain, can be increased following transcranial direct current stimulation of the hand motor cortex. Using high-definition transcranial direct current stimulation (HD-tDCS; 2 mA, 20 min), the current study aimed to examine the effects of elevated pain inhibitory capacity on endurance exercise performance. It was hypothesised that HD-tDCS would enhance the efficiency of the endogenous pain inhibitory response and improve endurance exercise performance. Methods Twelve healthy males between 18 and 40 years of age (M = 24.42 ± 3.85) were recruited for participation. Endogenous pain inhibitory capacity and exercise performance were assessed before and after both active and sham (placebo) stimulation. The conditioned pain modulation protocol was used for the measurement of pain inhibition. Exercise performance assessment consisted of both maximal voluntary contraction (MVC) and submaximal muscular endurance performance trials using isometric contractions of the non-dominant leg extensors. Results Active HD-tDCS (pre-tDCS, −.32 ± 1.33 kg; post-tDCS, −1.23 ± 1.21 kg) significantly increased pain inhibitory responses relative to the effects of sham HD-tDCS (pre-tDCS, −.91 ± .92 kg; post-tDCS, −.26 ± .92 kg; p = .046). Irrespective of condition, peak MVC force and muscular endurance was reduced from pre- to post-stimulation. HD-tDCS did not significantly influence this reduction in maximal force (active: pre-tDCS, 264.89 ± 66.87 Nm; post-tDCS, 236.33 ± 66.51 Nm; sham: pre-tDCS, 249.25 ± 88.56 Nm; post-tDCS, 239.63 ± 67.53 Nm) or muscular endurance (active: pre-tDCS, 104.65 ± 42.36 s; post-tDCS, 93.07 ± 33.73 s; sham: pre-tDCS, 123.42 ± 72.48 s; post-tDCS, 100.27 ± 44
Greenleaf, J. E.; Looft-Wilson, R.; Wisherd, J. L.; McKenzie, M. A.; Jensen, C. D.; Whittam, J. H.
Time to exhaustion at 87-91% of peak VO2 was measured in 5 untrained men (age: 31 +/- 8 years, body mass: 74.20 +/- 16.50 kg, body surface area: 1.90 +/- 0.24 m2, peak VO2: 2.87 +/- 0.40 l min-1, plasma volume: 3.21 +/- 0.88 l; means +/-SD) after consuming nothing (N) or two fluid formulations (10 ml kg-1, 743 +/- 161 ml): Performance 1 (P1), a multi-ionic carbohydrate drink, containing 55 mEq l-1 Na+, 4.16 g l-1 citrate, 20.49 g l-1 glucose, and 365 mOsm kg-1 H2O, and AstroAde (AA), a sodium chloride-sodium citrate hyperhydration drink, containing 164 mEq l-1 Na+, 8.54 g l-1 citrate, <5 mg l-1 glucose, and 253 mOsm kg-1 H2O. Mean (+/-SE) endurance for N, P1 and AA was 24.68 +/- 1.50, 24.55 +/- 1.09, and 30.50 +/- 3.44 min respectively. Percent changes in plasma volume (PV) from -105 min of rest to zero min before exercise were -1.5 +/- 3.2% (N), 0.2 +/- 2.2% (P1), and 4.8 +/- 3.0% (AA; P < 0.05). The attenuated endurance for N and P1 could not be attributed to differences in exercise metabolism (VE, RE, VO2) from the carbohydrate or citrate, terminal heart rate, levels of perceived exertion, forehead or thigh skin blood flow velocity, changes or absolute termination levels of rectal temperature. Thus, the higher level of resting PV for AA just before exercise, as well as greater acid buffering and possible increased energy substrate from citrate, may have contributed to the greater endurance.
Vaamonde, D; Da Silva, M E; Poblador, M S; Lancho, J L
The purpose of this study on non-professional (recreational) athletes was two-fold: 1) to determine if endurance exercise (EE) routinely used by professional athletes would produce reproductive changes in the general population, and 2) to assess reversion. Short-term exhaustive endurance exercise (EEE) can produce alterations in the hypothalamic-pituitary-gonadal (HPG) axis with subsequent fertility changes. Sixteen healthy adult male volunteers were divided into experimental (8) and control (8) groups for the exercise period. A cycloergometer provided EEE for a period of 2 weeks. The experimental group exercised four times a week; controls were without EEE. The hormonal and seminological profiles of all subjects were evaluated. Two weeks of EEE produced hormonal and seminological values in the experimental group that were statistically different from their own pre-treatment values (FSH: 3.33 +/- 1.7; LH: 3.73 +/- 1.36; sperm concentration/ml: 42.50 +/- 29.46; type a velocity: 25.23 +/- 10.9; type d velocity: 46.18 +/- 15.81; % of normal forms: 10.42 +/- 1.97) as well as from the pre- and post-treatment control group values. The measured parameters almost returned to pre-treatment levels in the experimental group 2 - 3 days after EEE ended. From this study we concluded that when subjected to EEE, individuals drawn from a recreational exercising life style experienced changes similar to those observed in studies done with athletes, and short-term EEE induced a reversible alteration to the HPG axis.
Scalzo, Rebecca L; Binns, Scott E; Klochak, Anna L; Giordano, Gregory R; Paris, Hunter L R; Sevits, Kyle J; Beals, Joseph W; Biela, Laurie M; Larson, Dennis G; Luckasen, Gary J; Irwin, David; Schroeder, Thies; Hamilton, Karyn L; Bell, Christopher
In hypoxia, endurance exercise performance is diminished; pharmacotherapy may abrogate this performance deficit. Based on positive outcomes in preclinical trials, we hypothesized that oral administration of methazolamide, a carbonic anhydrase inhibitor, aminophylline, a nonselective adenosine receptor antagonist and phosphodiesterase inhibitor, and/or methazolamide combined with aminophylline would attenuate hypoxia-mediated decrements in endurance exercise performance in humans. Fifteen healthy males (26 ± 5 years, body-mass index: 24.9 ± 1.6 kg/m(2); mean ± SD) were randomly assigned to one of four treatments: placebo (n = 9), methazolamide (250 mg; n = 10), aminophylline (400 mg; n = 9), or methazolamide (250 mg) with aminophylline (400 mg; n = 8). On two separate occasions, the first in normoxia (FIO2 = 0.21) and the second in hypoxia (FIO2 = 0.15), participants sat for 4.5 hours before completing a standardized exercise bout (30 minutes, stationary cycling, 100 W), followed by a 12.5-km time trial. The magnitude of time trial performance decrement in hypoxia versus normoxia did not differ between placebo (+3.0 ± 2.7 minutes), methazolamide (+1.4 ± 1.7 minutes), and aminophylline (+1.8 ± 1.2 minutes), all with p > 0.09; however, the performance decrement in hypoxia versus normoxia with methazolamide combined with aminophylline was less than placebo (+0.6 ± 1.5 minutes; p = 0.01). This improvement may have been partially mediated by increased SpO2 in hypoxia with methazolamide combined with aminophylline compared with placebo (73% ± 3% vs. 79% ± 6%; p < 0.02). In conclusion, coadministration of methazolamide and aminophylline may promote endurance exercise performance during a sojourn at high altitude.
Oga, Toru; Nishimura, Koichi; Tsukino, Mitsuhiro; Sato, Susumu
Endurance time on submaximal exercise tests is a sensitive measure in detecting changes after medical intervention and is used as an outcome in clinical trials, although there has been little discussion regarding the appropriate intensity. Therefore, we investigated whether there were differences in exercise responses between endurance tests at high versus moderate intensity, and analyzed which test was more appropriate. Thirty-seven patients with chronic obstructive pulmonary disease participated in the study. They performed cycle endurance tests at high and moderate submaximal workloads representing 80% and 60% of the maximum work rate reached on progressive cycle ergometry, respectively. Each type of exercise test was performed after inhaling salbutamol 400 microg, ipratropium bromide 80 microg or an identical placebo. Endurance time on the 80% endurance test was much shorter than on the 60% endurance test. The coefficients of variation for the endurance time were lower on the 80% test. Statistically significant improvements in the endurance time after bronchodilators in comparison to placebo were found only on the 80% test. When using the endurance time as an outcome, the high intensity endurance test is preferable to the moderate intensity endurance test, as the high intensity test demonstrated shorter exercise time, less variability and higher sensitivity.
Castell, L M; Newsholme, E A
Athletes undergoing intense, prolonged training or participating in endurance races suffer an increased risk of infection due to apparent immunosuppression. Glutamine is an important fuel for some cells of the immune system and may have specific immunostimulatory effects. The plasma glutamine concentration is lower after prolonged, exhaustive exercise: this may contribute to impairment of the immune system at a time when the athlete may be exposed to opportunistic infections. The effects of feeding glutamine was investigated both at rest in sedentary controls and after exhaustive exercise in middle-distance, marathon and ultra-marathon runners, and elite rowers, in training and competition. Questionnaires established the incidence of infection for 7 d after exercise: infection levels were highest in marathon and ultra-marathon runners, and in elite male rowers after intensive training. Plasma glutamine levels were decreased by approximately 20% 1 h after marathon running. A marked increase in numbers of white blood cells occurred immediately after exhaustive exercise, followed by a decrease in the numbers of lymphocytes. The provision of oral glutamine after exercise appeared to have a beneficial effect on the level of subsequent infections. In addition, the ratio of T-helper/T-suppressor cells appeared to be increased in samples from those who received glutamine, compared with placebo.
Mizuno, S; Morii, I; Tsuchiya, Y; Goto, K
The present study examined the effects of wearing a lower-body compression garment (CG) after endurance exercise on recovery of physiological function. 18 males were divided into 2 experiments, the downhill running (n=10, DHR) experiments and the level running (n=8, LR) experiments. Subjects performed 30 min of DHR (gradient: - 10%) or LR (gradient: 0%) at 70% of ˙VO2max with either wearing a CG (CG trial) or normal garment (CON trial) for 24 h after running. Changes in jump performance (counter movement jump; CMJ, rebound jump; RJ, drop jump; DJ), subjective feelings, circumferences of leg, and blood variables (creatine kinase, myoglobin, interleukin-6, high-sensitivity C-reactive protein) were evaluated before exercise, immediately after exercise, 1, 3 and 24 h following exercise. Running economy was evaluated at 24 h following exercise. CMJ height and RJ index were significantly higher in the CG trial than in the CON trial 24 h after running (P<0.05). Although changes in muscle soreness and blood variables were significantly greater in the DHR experiment than in the LR experiment, there was no significant difference between the trials in either experiment. Wearing a CG following endurance exercise facilitated recovery of jump performance under situations with severe exercise-induced muscle damage.
Kim, Dong-Hee; Kim, Seok-Hwan; Jeong, Woo-Seok; Lee, Ha-Yan
The increase rate of utilization of branched-chain amino acids (BCAA) by muscle is reduced to its plasma concentration during prolonged exercise leading to glycogen. BCAA supplementation would reduce the serum activities of intramuscular enzymes associated with muscle damage. To examine the effects of BCAA administration on fatigue substances (serotonin, ammonia and lactate), muscle damage substances (CK and LDH) and energy metabolism substances (FFA and glucose) after endurance exercise. Subjects (n = 26, college-aged males) were randomly divided into an experimental (n = 13, EXP) and a placebo (n = 13, CON) group. Subjects both EXP and CON performed a bout of cycle training (70% VO2max intensity) to exhaustion. Subject in the EXP were administrated BCAA (78ml/kg·w) prior to the bout of cycle exercise. Fatigue substances, muscle damage substances and energy metabolism substances were measured before ingesting BCAAs and placebos, 10 min before exercise, 30 min into exercise, immediately after exercise, and 30 min after exercise. Data were analyzed by two-way repeated measure ANCOVA, correlation and statistical significance was set at p < 0.05. The following results were obtained from this study; 1. In the change of fatigue substances : Serotonin in the EXP tended to decreased at the 10 min before exercise, 30 min into exercise, post exercise, and recovery 30 min. Serotonin in the CON was significantly greater than the EXP at the10 min before exercise and recovery 30. Ammonia in the EXP was increased at the 10 min before exercise, 30 min into exercise, and post exercise, but significantly decreased at the recovery 30min (p < 0.05). Ammonia in the CON was significantly lower than the EXP at the 10 min before exercise, 30 min into exercise, and post exercise (p < 0.05). Lactate in the EXP was significantly increased at the 30 min into exercise and significantly decreased at the post exercise and recovery 30 min. Lactate in the CON was significantly lower than the EXP
Zoladz, Jerzy A.; Majerczak, Joanna; Grassi, Bruno; Szkutnik, Zbigniew; Korostyński, Michał; Gołda, Sławomir; Grandys, Marcin; Jarmuszkiewicz, Wiesława; Kilarski, Wincenty; Karasinski, Janusz; Korzeniewski, Bernard
In this study we have examined the effect of prolonged endurance training program on the pulmonary oxygen uptake (V’O2) kinetics during heavy-intensity cycling-exercise and its impact on maximal cycling and running performance. Twelve healthy, physically active men (mean±SD: age 22.33±1.44 years, V’O2peak 3198±458 mL ∙ min-1) performed an endurance training composed mainly of moderate-intensity cycling, lasting 20 weeks. Training resulted in a decrease (by ~5%, P = 0.027) in V’O2 during prior low-intensity exercise (20 W) and in shortening of τp of the V’O2 on-kinetics (30.1±5.9 s vs. 25.4±1.5 s, P = 0.007) during subsequent heavy-intensity cycling. This was accompanied by a decrease of the slow component of V’O2 on-kinetics by 49% (P = 0.001) and a decrease in the end-exercise V’O2 by ~5% (P = 0.005). An increase (P = 0.02) in the vascular endothelial growth factor receptor 2 mRNA level and a tendency (P = 0.06) to higher capillary-to-fiber ratio in the vastus lateralis muscle were found after training (n = 11). No significant effect of training on the V’O2peak was found (P = 0.12). However, the power output reached at the lactate threshold increased by 19% (P = 0.01). The power output obtained at the V’O2peak increased by 14% (P = 0.003) and the time of 1,500-m performance decreased by 5% (P = 0.001). Computer modeling of the skeletal muscle bioenergetic system suggests that the training-induced decrease in the slow component of V’O2 on-kinetics found in the present study is mainly caused by two factors: an intensification of the each-step activation (ESA) of oxidative phosphorylation (OXPHOS) complexes after training and decrease in the ‘‘additional” ATP usage rising gradually during heavy-intensity exercise. PMID:27104346
Myrstad, Marius; Nystad, Wenche; Graff-Iversen, Sidsel; Thelle, Dag S; Stigum, Hein; Aarønæs, Marit; Ranhoff, Anette H
Emerging evidence suggests that endurance exercise increases the risk for atrial fibrillation (AF) in men, but few studies have investigated the dose-response relation between exercise and risk for atrial arrhythmias. Both exposure to exercise and reference points vary among studies, and previous studies have not differentiated between AF and atrial flutter. The aim of this study was to assess the risk for atrial arrhythmias by cumulative years of regular endurance exercise in men. To cover the range from physical inactivity to long-term endurance exercise, the study sample in this retrospective cohort study was based on 2 distinct cohorts: male participants in a long-distance cross-country ski race and men from the general population, in total 3,545 men aged ≥ 53 years. Arrhythmia diagnoses were validated by electrocardiograms during review of medical records. Regular endurance exercise was self-reported by questionnaire. A broad range of confounding factors was available for adjustment. The adjusted odds ratios per 10 years of regular endurance exercise were 1.16 (95% confidence interval 1.06 to 1.29) for AF and 1.42 (95% confidence interval 1.20 to 1.69) for atrial flutter. In stratified analyses, the associations were significant in cross-country skiers and in men from the general population. In conclusion, cumulative years of regular endurance exercise were associated with a gradually increased risk for AF and atrial flutter.
Demura, Shinichi; Yamada, Takayoshi; Terasawa, Naoko
This study examined the effect of coffee ingestion on physiological responses and ratings of perceived exertion (RPE) during submaximal endurance exercises by 10 healthy young adults. Participants performed a submaximal endurance cycling exercise corresponding to 60% of maximum oxygen uptake capacity for 60 min. They drank either caffeinated coffee with a caffeine content of 6 mg/kg body-mass of each participant (Caf) or a decaffeinated coffee (Dec) 60 min. before starting exercise. Participants participated in the blind design experiment under both conditions at a one-week interval. Oxygen uptake, respiratory exchange ratio, heart rate, RPE, and plasma lactate concentration were measured during the endurance exercise. The RPE under the Caffeinated coffee condition during the last 60 min. of endurance exercise was significantly lower than that in the Decaffeinated coffee condition. However, no significant differences in any physiological response were observed between conditions. Thus, caffeine ingestion 60 min. before starting exercise had an insignificant effect on the physiological responses, except for RPE during submaximal endurance exercises for 60 min. Caffeine ingestion before endurance exercise of relatively low intensity may have a beneficial effect on psychological responses.
Robson-Ansley, Paula; Walshe, Ian; Ward, Douglas
The aim of our study was twofold, firstly to examine the relationship between plasma concentrations of IL-6, hepcidin and iron following prolonged exercise and secondly, to assess the effect of carbohydrate ingestion on circulating hepcidin concentration post-exercise. The study was a randomised double-blind cross-over design, with participants consuming either a carbohydrate (CHO) or an isovolumetric placebo drink throughout the trial. Nine healthy, trained males completed a treadmill run at 60% vVO(2max) for 120 min followed by a 5 km time trial. Plasma concentrations of both IL-6 and hepcidin significantly increased post-exercise following both trials (p<.05) and returned to baseline by 24 h post (p>.05). A positive correlation between hepcidin and IL-6 was demonstrated immediately following exercise during PLA while there was a trend for a moderate correlation during CHO (PLA trial rho=0.81, p<0.001; CHO trial rho=0.36, p=0.07). Plasma iron was unaffected immediately post-exercise but significantly reduced by 24 h post-exercise compared to baseline. CHO ingestion significantly reduced post-exercise IL-6 (p<.05) but this had no effect on plasma hepcidin or iron concentration. Our data demonstrate CHO supplementation does not alter the rapid hepcidin response associated with exercise and does not prevent a subsequent fall in plasma iron concentration. This finding adds further support to the theory that an exercise-induced, up-regulation of hepcidin activity is a mechanism causing iron deficiency in endurance athletes.
Nazar, K.; Greenleaf, J. E.; Pohoska, E.; Turlejska, E.; Kaciuba-Uscilko, H.; Kozlowski, S.
Physiological effects of restricted activity (RA) and subsequent retraining have been studied. Ten male mongrel dogs performed a submaximal exercise endurance test on a treadmill during kennel control, after 8 weeks of cage confinement and after eight weeks of retraining using the same treadmill protocol 1 h/d for 6 d/week. Data obtained show that RA reduces exercise endurance, the effectiveness of exercise thermoregulation, muscle glycogen stores, and the lipolytic response to exercise and to noradrenaline stimulation.
Convertino, V. A.
Exercise represents the primary countermeasure used during spaceflight to maintain or restore maximal aerobic capacity (VO2max), musculoskeletal structure, and orthostatic function. However, no single exercise or combination of prescriptions has proven entirely effective in restoring cardiovascular and musculoskeletal functions to preflight levels following prolonged spaceflight. As human spaceflight exposures increase in duration, assessment and development of various effective exercise-based protective procedures become paramount. This must involve improvement in specific countermeasure prescription as well as development of additional approaches that will allow space travelers greater flexibility and medical safety during long flights. Effective exercise prescription will be based on identification of basic physiological stimuli that maintain normal function in terrestrial gravity and understanding of how specific combinations of exercise characteristics e.g., duration, frequency, intensity, mode) can mimic these stimuli and affect the overall process of adaptation to microgravity. This can be accomplished only with greater emphasis of research on ground-based experiments. Future attention must be directed to improving exercise compliance while minimizing both crew time and the impact of the exercise on life-support resources.
González-Alonso, José; Calbet, José A L; Nielsen, Bodil
The present study examined whether the blood flow to exercising muscles becomes reduced when cardiac output and systemic vascular conductance decline with dehydration during prolonged exercise in the heat. A secondary aim was to determine whether the upward drift in oxygen consumption (V̇O2) during prolonged exercise is confined to the active muscles.Seven euhydrated, endurance-trained cyclists performed two bicycle exercise trials in the heat (35 °C; 40–50% relative humidity; 61 ± 2% of maximal V̇O2), separated by 1 week. During the first trial (dehydration trial, DE), they bicycled until volitional exhaustion (135 ± 4 min, mean ± s.e.m.), while developing progressive dehydration and hyperthermia (3.9 ± 0.3% body weight loss; 39.7 ± 0.2 °C oesophageal temperature, Toes). In the second trial (control trial), they bicycled for the same period of time while maintaining euhydration by ingesting fluids and stabilizing Toes at 38.2 ± 0.1 °C after 30 min exercise.In both trials, cardiac output, leg blood flow (LBF), vascular conductance and V̇O2 were similar after 20 min exercise. During the 20 min-exhaustion period of DE, cardiac output, LBF and systemic vascular conductance declined significantly (8–14%; P < 0.05) yet muscle vascular conductance was unaltered. In contrast, during the same period of control, all these cardiovascular variables tended to increase. After 135 ± 4 min of DE, the 2.0 ± 0.6 l min−1 lower blood flow to the exercising legs accounted for approximately two-thirds of the reduction in cardiac output. Blood flow to the skin also declined markedly as forearm blood flow was 39 ± 8% (P < 0.05) lower in DE vs. control after 135 ± 4 min.In both trials, whole body V̇O2 and leg V̇O2 increased in parallel and were similar throughout exercise. The reduced leg blood flow in DE was accompanied by an even greater increase in femoral arterial-venous O2 (a-vO2) difference.It is concluded that blood flow to the exercising muscles declines
Pan, Jeong Hoon; Kim, Jun Ho; Kim, Hyung Min; Lee, Eui Seop; Shin, Dong-Hoon; Kim, Seongpil; Shin, Minkyeong; Kim, Sang Ho; Lee, Jin Hyup; Kim, Young Jun
Acetic acid has been shown to promote glycogen replenishment in skeletal muscle during exercise training. In this study, we investigated the effects of acetic acid on endurance capacity and muscle oxidative metabolism in the exercise training using in vivo mice model. In exercised mice, acetic acid induced a significant increase in endurance capacity accompanying a reduction in visceral adipose depots. Serum levels of non-esterified fatty acid and urea nitrogen were significantly lower in acetic acid-fed mice in the exercised mice. Importantly, in the mice, acetic acid significantly increased the muscle expression of key enzymes involved in fatty acid oxidation and glycolytic-to-oxidative fiber-type transformation. Taken together, these findings suggest that acetic acid improves endurance exercise capacity by promoting muscle oxidative properties, in part through the AMPK-mediated fatty acid oxidation and provide an important basis for the application of acetic acid as a major component of novel ergogenic aids.
Background Life expectancy at birth in the first world has increased from 35 years at the beginning of the 20th century to more than 80 years now. The increase in life expectancy has resulted in an increase in age-related diseases and larger numbers of frail and dependent people. The aim of our study was to determine whether life-long spontaneous aerobic exercise affects lifespan and healthspan in mice. Results Male C57Bl/6J mice, individually caged, were randomly assigned to one of two groups: sedentary (n = 72) or spontaneous wheel-runners (n = 72). We evaluated longevity and several health parameters including grip strength, motor coordination, exercise capacity (VO2max) and skeletal muscle mitochondrial biogenesis. We also measured the cortical levels of the brain-derived neurotrophic factor (BDNF), a neurotrophin associated with brain plasticity. In addition, we measured systemic oxidative stress (malondialdehyde and protein carbonyl plasma levels) and the expression and activity of two genes involved in antioxidant defense in the liver (that is, glutathione peroxidase (GPx) and manganese superoxide dismutase (Mn-SOD)). Genes that encode antioxidant enzymes are considered longevity genes because their over-expression may modulate lifespan. Aging was associated with an increase in oxidative stress biomarkers and in the activity of the antioxidant enzymes, GPx and Mn-SOD, in the liver in mice. Life-long spontaneous exercise did not prolong longevity but prevented several signs of frailty (that is, decrease in strength, endurance and motor coordination). This improvement was accompanied by a significant increase in the mitochondrial biogenesis in skeletal muscle and in the cortical BDNF levels. Conclusion Life-long spontaneous exercise does not prolong lifespan but improves healthspan in mice. Exercise is an intervention that delays age-associated frailty, enhances function and can be translated into the clinic. PMID:24472376
Junge, Nicklas; Jørgensen, Rasmus; Flouris, Andreas D.; Nybo, Lars
ABSTRACT In this review we examine how self-paced performance is affected by environmental heat stress factors during cycling time trial performance as well as considering the effects of exercise mode and heat acclimatization. Mean power output during prolonged cycling time trials in the heat (≥30°C) was on average reduced by 15% in the 14 studies that fulfilled the inclusion criteria. Ambient temperature per se was a poor predictor of the integrated environmental heat stress and 2 of the prevailing heat stress indices (WBGT and UTCI) failed to predict the environmental influence on performance. The weighing of wind speed appears to be too low for predicting the effect for cycling in trained acclimatized subjects, where performance may be maintained in outdoor time trials at ambient temperatures as high as 36°C (36°C UTCI; 28°C WBGT). Power output during indoor trials may also be maintained with temperatures up to at least 27°C when humidity is modest and wind speed matches the movement speed generated during outdoor cycling, whereas marked reductions are observed when air movement is minimal. For running, representing an exercise mode with lower movement speed and higher heat production for a given metabolic rate, it appears that endurance is affected even at much lower ambient temperatures. On this basis we conclude that environmental heat stress impacts self-paced endurance performance. However, the effect is markedly modified by acclimatization status and exercise mode, as the wind generated by the exercise (movement speed) or the environment (natural or fan air movement) exerts a strong influence. PMID:28090557
Junge, Nicklas; Jørgensen, Rasmus; Flouris, Andreas D; Nybo, Lars
In this review we examine how self-paced performance is affected by environmental heat stress factors during cycling time trial performance as well as considering the effects of exercise mode and heat acclimatization. Mean power output during prolonged cycling time trials in the heat (≥30°C) was on average reduced by 15% in the 14 studies that fulfilled the inclusion criteria. Ambient temperature per se was a poor predictor of the integrated environmental heat stress and 2 of the prevailing heat stress indices (WBGT and UTCI) failed to predict the environmental influence on performance. The weighing of wind speed appears to be too low for predicting the effect for cycling in trained acclimatized subjects, where performance may be maintained in outdoor time trials at ambient temperatures as high as 36°C (36°C UTCI; 28°C WBGT). Power output during indoor trials may also be maintained with temperatures up to at least 27°C when humidity is modest and wind speed matches the movement speed generated during outdoor cycling, whereas marked reductions are observed when air movement is minimal. For running, representing an exercise mode with lower movement speed and higher heat production for a given metabolic rate, it appears that endurance is affected even at much lower ambient temperatures. On this basis we conclude that environmental heat stress impacts self-paced endurance performance. However, the effect is markedly modified by acclimatization status and exercise mode, as the wind generated by the exercise (movement speed) or the environment (natural or fan air movement) exerts a strong influence.
Périard, Julien D; Cramer, Matthew N; Chapman, Phillip G; Caillaud, Corinne; Thompson, Martin W
It has been proposed that self-paced exercise in the heat is regulated by an anticipatory reduction in work rate based on the rate of heat storage. However, performance may be impaired by the development of hyperthermia and concomitant rise in cardiovascular strain increasing relative exercise intensity. This study evaluated the influence of thermal strain on cardiovascular function and power output during self-paced exercise in the heat. Eight endurance-trained cyclists performed a 40 km simulated time trial in hot (35°C) and thermoneutral conditions (20°C), while power output, mean arterial pressure, heart rate, oxygen uptake and cardiac output were measured. Time trial duration was 64.3 ± 2.8 min (242.1 W) in the hot condition and 59.8 ± 2.6 min (279.4 W) in the thermoneutral condition (P < 0.01). Power output in the heat was depressed from 20 min onwards compared with exercise in the thermoneutral condition (P < 0.05). Rectal temperature reached 39.8 ± 0.3 (hot) and 38.9 ± 0.2°C (thermoneutral; P < 0.01). From 10 min onwards, mean skin temperature was ~7.5°C higher in the heat, and skin blood flow was significantly elevated (P < 0.01). Heart rate was ~8 beats min(-1) higher throughout hot exercise, while stroke volume, cardiac output and mean arterial pressure were significantly depressed compared with the thermoneutral condition (P < 0.05). Peak oxygen uptake measured during the final kilometre of exercise at maximal effort reached 77 (hot) and 95% (thermoneutral) of pre-experimental control values (P < 0.01). We conclude that a thermoregulatory-mediated rise in cardiovascular strain is associated with reductions in sustainable power output, peak oxygen uptake and maximal power output during prolonged, intense self-paced exercise in the heat.
Pitetti, K H; Barrett, P J; Abbas, D
The purpose of this case study was to determine whether an individual who had residual deficits following an acute incidence of Guillain-Barre Syndrome (GBS) would experience improved physiological adaptations following aerobic endurance training. A 57-year-old man who needed the aid of a crutch for walking three years following an acute bout of GBS participated in this study. Peak work level (watts), oxygen consumption (VO2 mL/min; mL/kg.min), and ventilation (VE, L/min) were determined on a bicycle ergometer (BE), a Schwinn Air-Dyne ergometer (SAE), and an arm crank ergometer (ACE) before and after exercise training. Isokinetic leg strength measured using a dynamometer and total work capacity in watts using BE were also determined before and after training. The subject trained for 16 weeks at an approximate frequency of 3 days/week, an average duration of 30 minutes, and an average intensity of 75% to 80% of pretraining peak HR. A 9% and 11% improvement was seen in peak oxygen consumption for the SAE and BE, respectively. For peak ventilation, a 23% and 11% improvement was seen for the SAE and BE, respectively. For the ACE, a 16% increase in peak ventilation was seen, with no improvement in aerobic capacity. Total work capacity on the BE was improved by 29% following training. Positive improvements were also seen in isokinetic leg strength. This study demonstrated that a man still suffering residual symptoms following an incidence of GBS was able to improve his cardiopulmonary and work capacity and isokinetic strength of his legs following a supervised training program using the SAE. The subject also reported improvements in activities of daily living.
Rosenkilde, Mads; Reichkendler, Michala Holm; Auerbach, Pernille; Toräng, Signe; Gram, Anne Sofie; Ploug, Thorkil; Holst, Jens Juul; Sjödin, Anders; Stallknecht, Bente
Weight loss induced by endurance exercise is often disappointing, possibly due to an increase in energy intake mediated through greater appetite. The aim of this study was to evaluate fasting, postprandial, and postexercise appetite regulation after an intervention prescribing two amounts of endurance exercise. Sixty-four sedentary, overweight, healthy young men were randomized to control (CON), moderate-dose (MOD: ≈ 30 min/day), or high-dose (HIGH: ≈ 60 min/day) endurance exercise for 12 wk. Along with subjective appetite ratings, plasma ghrelin, glucagon, insulin, peptide YY3-36, glucose, free fatty acids, and glycerol were measured during fasting and in relation to a breakfast meal and an acute bout of exercise, both at baseline and at follow-up. Ad libitum lunch energy intake was evaluated 3 h after the breakfast meal. Despite different amounts of endurance exercise, the subjects lost similar amounts of fat mass (MOD: 4.2 ± 0.5 kg; HIGH: 3.7 ± 0.5 kg). Fasting and postprandial insulin decreased ≈ 20% in both exercise groups (P < 0.03 vs. CON). Appetite measurements were not upregulated in the fasting and postprandial states. On the contrary, fasting and postprandial ratings of fullness and postprandial PYY3-36 increased in HIGH (P < 0.001 vs. CON). Ad libitum lunch energy intake remained unchanged over the course of the intervention. In both exercise groups, plasma ghrelin increased in relation to acute exercise after training. Thus neither moderate nor high doses of daily endurance exercise increased fasting and postprandial measures of appetite, but a high dose of exercise was associated with an increase in fasting and meal-related ratings of fullness and satiety.
Taubert, Marco; Villringer, Arno; Lehmann, Nico
Endurance exercise improves cardiovascular and musculoskeletal function and may also increase the information processing capacities of the brain. Animal and human research from the past decade demonstrated widespread exercise effects on brain structure and function at the systems-, cellular-, and molecular level of brain organization. These neurobiological mechanisms may explain the well-established positive influence of exercise on performance in various behavioral domains but also its contribution to improved skill learning and neuroplasticity. With respect to the latter, only few empirical and theoretical studies are available to date. The aim of this review is (i) to summarize the existing neurobiological and behavioral evidence arguing for endurance exercise-induced improvements in motor learning and (ii) to develop hypotheses about the mechanistic link between exercise and improved learning. We identify major knowledge gaps that need to be addressed by future research projects to advance our understanding of how exercise should be organized to optimize motor learning. PMID:26834602
Van Soeren, M H; Graham, T E
In this study the effects of acute caffeine ingestion on exercise performance, hormonal (epinephrine, norepinephrine, insulin), and metabolic (free fatty acids, glycerol, glucose, lactate, expired gases) parameters during short-term withdrawal from dietary caffeine were investigated. Recreational athletes who were habitual caffeine users (n = 6) (maximum oxygen uptake 54.5 +/- 3.3 ml x kg-1 x min-1 and daily caffeine intake 761.3 +/- 11.8 mg/day) were tested under conditions of no withdrawal and 2-day and 4-day withdrawal from dietary caffeine. There were seven trials in total with a minimum of 10 days between trials. On the day of the exercise trial, subjects ingested either dextrose placebo or 6 mg/kg caffeine in capsule form 1 h before cycle ergometry to exhaustion at 80-85% of maximum oxygen uptake. Test substances were assigned in a random, double-blind manner. A final placebo control trial completed the experiment. There was no significant difference in any measured parameters among days of withdrawal after ingestion of placebo. At exhaustion in the 2- and 4-day withdrawal trials, there were significant increases in plasma norepinephrine in response to caffeine ingestion. Caffeine-induced increases in serum free fatty acids occurred after 4 days and only at rest. Subjects responded to caffeine with increases in plasma epinephrine (P < 0.05) at exhaustion and prolonged exercise time in all caffeine trials compared with placebo, regardless of withdrawal from caffeine. It is concluded that increased endurance is unrelated to hormonal or metabolic changes and that it is not related to prior caffeine habituation in recreational athletes.
Seo, Dae Yun; Lee, Sung Ryul; Kwak, Hyo-Bum; Seo, Kyo Won; McGregor, Robin A; Yeo, Ji Young; Ko, Tae Hee; Bolorerdene, Saranhuu; Kim, Nari; Ko, Kyung Soo; Rhee, Byoung Doo
Involuntary physical activity induced by the avoidance of electrical shock leads to improved endurance exercise capacity in animals. However, it remains unknown whether voluntary stand-up physical activity (SPA) without forced simulating factors improves endurance exercise capacity in animals. We examined the eff ects of SPA on body weight, cardiac function, and endurance exercise capacity for 12 weeks. Twelve male Sprague-Dawley rats (aged 8 weeks, n=6 per group) were randomly assigned to a control group (CON) or a voluntary SPA group. The rats were induced to perform voluntary SPA (lifting a load equal to their body weight), while the food height (18.0 cm) in cages was increased progressively by 3.5 every 4 weeks until it reached 28.5 cm for 12 weeks. The SPA group showed a lower body weight compared to the CON group, but voluntary SPA did not affect the skeletal muscle and heart weights, food intake, and echocardiography results. Although the SPA group showed higher grip strength, running time, and distance compared to the CON group, the level of irisin, corticosterone, genetic expression of mitochondrial biogenesis, and nuclei numbers were not affected. These findings show that voluntary SPA without any forced stimuli in rats can eff ectively reduce body weight and enhance endurance exercise capacity, suggesting that it may be an important alternative strategy to enhance endurance exercise capacity. PMID:27162483
Jones, Thomas W; Howatson, Glyn; Russell, Mark; French, Duncan N
The present study examined the effect of strength and endurance training order on the endocrine milieu associated with strength development and performance during concurrent training. A randomised, between-groups design was employed with 30 recreationally resistance-trained males completing one of four acute experimental training protocols; strength training (ST), strength followed by endurance training (ST-END), endurance followed by strength training (END-ST) or no training (CON). Blood samples were taken before each respective exercise protocol, immediately upon cessation of exercise, and 1 h post cessation of exercise. Blood samples were subsequently analysed for total testosterone, cortisol and lactate concentrations. Ability to maintain 80% 1RM during strength training was better in ST and ST-END than END-ST (both p < .05). Immediately following the respective exercise protocols all training interventions elicited significant increases in testosterone (p < .05). ST and END-ST resulted in greater increases in cortisol than ST-END (both p < .05). The testosterone:cortisol ratio was similar following the respective exercise protocols. Blood lactate concentrations post-training were greater following END-ST and ST than ST-END (both p < .05). Conducting endurance exercise prior to strength training resulted in impaired strength training performance. Blood cortisol and lactate concentrations were greater when endurance training was conducted prior to strength training than vice versa. As such, it may be suggested that conducting endurance prior to strength training may result in acute unfavourable responses to strength training when strength training is conducted with high loads.
Barbosa, Luis F.; Denadai, Benedito S.; Greco, Camila C.
Slow component of oxygen uptake (VO2SC) kinetics and maximal oxygen uptake (VO2max) attainment seem to influence endurance performance during constant-work rate exercise (CWR) performed within the severe intensity domain. In this study, it was hypothesized that delaying the attainment of VO2max by reducing the rates at which VO2 increases with time (VO2SC kinetics) would improve the endurance performance during severe-intensity intermittent exercise performed with different work:recovery duration and recovery type in active individuals. After the estimation of the parameters of the VO2SC kinetics during CWR exercise, 18 males were divided into two groups (Passive and Active recovery) and performed at different days, two intermittent exercises to exhaustion (at 95% IVO2max, with work: recovery ratio of 2:1) with the duration of the repetitions calculated from the onset of the exercise to the beginning of the VO2SC (Short) or to the half duration of the VO2SC (Long). The active recovery was performed at 50% IVO2max. The endurance performance during intermittent exercises for the Passive (Short = 1523 ± 411; Long = 984 ± 260 s) and Active (Short = 902 ± 239; Long = 886 ± 254 s) groups was improved compared with CWR condition (Passive = 540 ± 116; Active = 489 ± 84 s). For Passive group, the endurance performance was significantly higher for Short than Long condition. However, no significant difference between Short and Long conditions was found for Active group. Additionally, the endurance performance during Short condition was higher for Passive than Active group. The VO2SC kinetics was significantly increased for CWR (Passive = 0.16 ± 0.04; Active = 0.16 ± 0.04 L.min−2) compared with Short (Passive = 0.01 ± 0.01; Active = 0.03 ± 0.04 L.min−2) and Long (Passive = 0.02 ± 0.01; Active = 0.01 ± 0.01 L.min−2) intermittent exercise conditions. No significant difference was found among the intermittent exercises. It can be concluded that the endurance
She, Pengxiang; Zhou, Yingsheng; Zhang, Zhiyou; Griffin, Kathleen; Gowda, Kavitha; Lynch, Christopher J
Exercise enhances branched-chain amino acid (BCAA) catabolism, and BCAA supplementation influences exercise metabolism. However, it remains controversial whether BCAA supplementation improves exercise endurance, and unknown whether the exercise endurance effect of BCAA supplementation requires catabolism of these amino acids. Therefore, we examined exercise capacity and intermediary metabolism in skeletal muscle of knockout (KO) mice of mitochondrial branched-chain aminotransferase (BCATm), which catalyzes the first step of BCAA catabolism. We found that BCATm KO mice were exercise intolerant with markedly decreased endurance to exhaustion. Their plasma lactate and lactate-to-pyruvate ratio in skeletal muscle during exercise and lactate release from hindlimb perfused with high concentrations of insulin and glucose were significantly higher in KO than wild-type (WT) mice. Plasma and muscle ammonia concentrations were also markedly higher in KO than WT mice during a brief bout of exercise. BCATm KO mice exhibited 43-79% declines in the muscle concentration of alanine, glutamine, aspartate, and glutamate at rest and during exercise. In response to exercise, the increments in muscle malate and alpha-ketoglutarate were greater in KO than WT mice. While muscle ATP concentration tended to be lower, muscle IMP concentration was sevenfold higher in KO compared with WT mice after a brief bout of exercise, suggesting elevated ammonia in KO is derived from the purine nucleotide cycle. These data suggest that disruption of BCAA transamination causes impaired malate/aspartate shuttle, thereby resulting in decreased alanine and glutamine formation, as well as increases in lactate-to-pyruvate ratio and ammonia in skeletal muscle. Thus BCAA metabolism may regulate exercise capacity in mice.
Stelzer, I; Kröpfl, J M; Fuchs, R; Pekovits, K; Mangge, H; Raggam, R B; Gruber, H-J; Prüller, F; Hofmann, P; Truschnig-Wilders, M; Obermayer-Pietsch, B; Haushofer, A C; Kessler, H H; Mächler, P
Although amateur sports have become increasingly competitive within recent decades, there are as yet few studies on the possible health risks for athletes. This study aims to determine the impact of ultra-endurance exercise-induced stress on the number and function of circulating hematopoietic progenitor cells (CPCs) and hematological, inflammatory, clinical, metabolic, and stress parameters in moderately trained amateur athletes. Following ultra-endurance exercise, there were significant increases in leukocytes, platelets, interleukin-6, fibrinogen, tissue enzymes, blood lactate, serum cortisol, and matrix metalloproteinase-9. Ultra-endurance exercise did not influence the number of CPCs but resulted in a highly significant decline of CPC functionality after the competition. Furthermore, Epstein-Barr virus was seen to be reactivated in one of seven athletes. The link between exercise-induced stress and decline of CPC functionality is supported by a negative correlation between cortisol and CPC function. We conclude that ultra-endurance exercise induces metabolic stress and an inflammatory response that affects not only mature hematopoietic cells but also the function of the immature hematopoietic stem and progenitor cell fraction, which make up the immune system and provide for regeneration.
Howe, Stephanie M; Hand, Taryn M; Larson-Meyer, D Enette; Austin, Kathleen J; Alexander, Brenda M; Manore, Melinda M
In endurance-trained men, an acute bout of exercise is shown to suppress post-exercise appetite, yet limited research has examined this response in women. The purpose of this study was to investigate the effect of exercise intensity on appetite and gut hormone responses in endurance-trained women. Highly-trained women (n = 15, 18-40 years, 58.4 ± 6.4 kg, VO2MAX = 55.2 ± 4.3 mL/kg/min) completed isocaloric bouts (500 kcals or 2093 kJ) of moderate-intensity (MIE, 60% VO2MAX) and high-intensity (HIE, 85% VO2MAX) treadmill running at the same time of day, following a similar 48-h diet/exercise period, and at least 1-week apart. Blood was drawn pre-exercise (baseline), immediately post-exercise and every 20-min for the next 60-min. Plasma concentrations of acylated ghrelin, PYY3-36, GLP-1 and subjective appetite ratings via visual analog scale (VAS) were assessed at each time point. Acylated ghrelin decreased (p = 0.014) and PYY3-36 and GLP-1 increased (p = 0.036, p < 0.0001) immediately post-exercise, indicating appetite suppression. VAS ratings of hunger and desire to eat decreased immediately post-exercise (p = 0.0012, p = 0.0031, respectively), also indicating appetite suppression. There were no differences between exercise intensities for appetite hormones or VAS. Similar to males, post-exercise appetite regulatory hormones were altered toward suppression in highly-trained women and independent of energy cost of exercise. Results are important for female athletes striving to optimize nutrition for endurance performance.
Howe, Stephanie M.; Hand, Taryn M.; Larson-Meyer, D. Enette; Austin, Kathleen J.; Alexander, Brenda M.; Manore, Melinda M.
In endurance-trained men, an acute bout of exercise is shown to suppress post-exercise appetite, yet limited research has examined this response in women. The purpose of this study was to investigate the effect of exercise intensity on appetite and gut hormone responses in endurance-trained women. Highly-trained women (n = 15, 18–40 years, 58.4 ± 6.4 kg, VO2MAX = 55.2 ± 4.3 mL/kg/min) completed isocaloric bouts (500 kcals or 2093 kJ) of moderate-intensity (MIE, 60% VO2MAX) and high-intensity (HIE, 85% VO2MAX) treadmill running at the same time of day, following a similar 48-h diet/exercise period, and at least 1-week apart. Blood was drawn pre-exercise (baseline), immediately post-exercise and every 20-min for the next 60-min. Plasma concentrations of acylated ghrelin, PYY3–36, GLP-1 and subjective appetite ratings via visual analog scale (VAS) were assessed at each time point. Acylated ghrelin decreased (p = 0.014) and PYY3–36 and GLP-1 increased (p = 0.036, p < 0.0001) immediately post-exercise, indicating appetite suppression. VAS ratings of hunger and desire to eat decreased immediately post-exercise (p = 0.0012, p = 0.0031, respectively), also indicating appetite suppression. There were no differences between exercise intensities for appetite hormones or VAS. Similar to males, post-exercise appetite regulatory hormones were altered toward suppression in highly-trained women and independent of energy cost of exercise. Results are important for female athletes striving to optimize nutrition for endurance performance. PMID:27096869
Frinchi, M; Macaluso, F; Licciardi, A; Perciavalle, V; Coco, M; Belluardo, N; Morici, G; Mudò, G
The lack of dystrophin in mdx mice leads to cycles of muscle degeneration and regeneration processes. Various strategies have been proposed in order to reduce the muscle-wasting component of muscular dystrophy, including implementation of an exercise programme. The aim of this study was to examine how low-intensity endurance exercise affects the degeneration-regeneration process in dystrophic muscle of male mdx mice. Mice were subjected to low-intensity endurance exercise by running on a motorized Rota-Rod for 5 days/week for 6 weeks. Histomorphological analysis showed a significant reduction of measured inflammatory-necrotic areas in both gastrocnemius and quadriceps muscle of exercised mdx mice as compared to matched sedentary mdx mice. The degenerative-regenerative process was also evaluated by examining the protein levels of connexin 39 (Cx39), a specific gene expressed in injured muscles. Cx39 was not detected in sedentary wild type mice, whereas it was found markedly increased in sedentary mdx mice, revealing active muscle degeneration-regeneration process. These Cx39 protein levels were significantly reduced in muscles of mdx mice exercised for 30 and 40 days, revealing together with histomorphological analysis a strong reduction of degeneration process in mice subjected to low-intensity endurance exercise. Muscles of exercised mdx mice did not show significant changes in force and fatigue resistance as compared to sedentary mdx mice. Overall in this study we found that specific low-intensity endurance exercise induces a beneficial effect probably by reducing the degeneration of dystrophic muscle.
Weinstein, R B; Full, R J
Most animals move intermittently, yet many proposed performance limitations of terrestrial locomotion are based on steady-state measurements and assumptions. We examined the effect of work-rest transitions by exercising the ghost crab, Ocypode quadrata (28.1 +/- 8.1 g), intermittently on a treadmill at 0.30 m/s, a supramaximal speed [i.e., greater than the speed that elicits the maximal rate of oxygen consumption (VO2)]. Duration of the exercise and pause periods, ratio of exercise to pause, and speed during the exercise period were varied to determine the effect on performance. Crabs fatigued after 7.5 min of continuous running, a distance capacity (i.e., total distance traveled before fatigue) of 135 m. When the task was done intermittently with 2-min exercise and 2-min pause periods, the crabs fatigued after 87 min (a total distance of 787 m), representing an 5.8-fold increase in distance capacity compared with continuous exercise at the same absolute speed (0.30 m/s) and a 2.2-fold increase in distance capacity compared with continuous exercise at the same average speed (0.15 m/s). Pause periods less than 30 s did not result in greater distance capacity compared with continuous exercise at the same average speed. Longer (3-5 min) and shorter exercise periods (less than or equal to 30 s) decreased distance capacity. Leg muscle lactate increased 10-fold to 15 mumol/g leg during intermittent exercise. However, significant amounts of lactate were cleared from the leg during the brief pause periods.(ABSTRACT TRUNCATED AT 250 WORDS)
Almonds are a healthy tree nut food with high nutrient density. Their consumption has been shown to ameliorate oxidative stress, inflammation, etc. The objective of the study was to examine the effect of almonds on elements of endurance exercise performance in trained athletes. A 10-week crossover, ...
UBA) at 50 feet of seawater. The MK 16 UBA has turbulent inspiratory and laminar expiratory pressure drops. At the design flow, expiratory pressure was...twice inspiratory pressure. Endurance was assessed as duration of exercise on a bicycle ergometer at 85% peak oxygen consumption. Ventilatory...Respiratory duty cycle, percentage change from baseline...................... 19 Figure 10. Inspiratory and expiratory times, percentage change from
Physician and Sportsmedicine, 1987
In a roundtable format, five doctors explore the reasons why regular physical activity should continue to play a significant role in the rehabilitation of patients with coronary artery disease. Endurance exercise training improves aerobic capacity, reduces blood pressure, and decreases risk. (Author/MT)
Frontera, Walter R.; Adams, Richard P.
The physiologic and metabolic adjustments of the body to a single endurance exercise session are analyzed in terms of the respiratory system, the cardiovascular system, and oxygen delivery to the muscles. Patients with cardiorespiratory and neuromuscular diseases are compared to normal individuals. (Author/MT)
Cornelissen, Véronique A; Buys, Roselien; Smart, Neil A
Exercise is widely recommended as one of the key preventive lifestyle changes to reduce the risk of hypertension and to manage high blood pressure (BP), but individual studies investigating the effect of exercise on ambulatory BP have remained inconclusive. Therefore, the primary purpose of this systematic review and meta-analysis was to determine the effect of aerobic endurance training on daytime and night-time BP in healthy adults. A systematic literature search was conducted using PubMed and Cochrane Controlled Clinical trial registry from their inception to May 2012. Randomized controlled trials of at least 4 weeks investigating the effects of aerobic endurance training on ambulatory BP in healthy adults were included. Inverse weighted random effects models were used for analyses, with data reported as weighted means and 95% confidence limits. We included 15 randomized controlled trials, involving 17 study groups and 633 participants (394 exercise participants and 239 control participants). Overall, endurance training induced a significant reduction in daytime SBP [-3.2 mmHg, 95% confidence interval (CI), -5.0 to-1.3] and daytime DBP (-2.7 mmHg, 95% CI, -3.9 to -1.5). No effect was observed on night-time BP. The findings from this meta-analysis suggest that aerobic endurance exercise significantly decreases daytime, but not night-time, ambulatory BP.
Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bond, M.; Bulbulian, R.
The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle orgometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.
Greenleaf, J. E.; Bernauer, E. M.; Ertl, A. C.; Bulbulian, R.; Bond, M.
The purpose of our study was to determine if an intensive, intermittent, isokinetic, lower extremity exercise training program would attenuate or eliminate the decrease of muscular strength and endurance during prolonged bed rest (BR). The 19 male subjects (36 +/- 1 yr, 178 +/- 2 cm, 76.5 +/- 1.7 kg) were allocated into a no exercise (NOE) training group (N = 5), an isotonic (lower extremity cycle ergometer) exercise (ITE) training group (N = 7), and an isokinetic (isokinetic knee flexion-extension) exercise (IKE) training group (N = 7). Peak knee (flexion and extension) and shoulder (abduction-adduction) functions were measured weekly in all groups with one 5-repetition set. After BR, average knee extension total work decreased by 16% with NOE, increased by 27% with IKE, and was unchanged with ITE. Average knee flexion total work and peak torque (strength) responses were unchanged in all groups. Force production increased by 20% with IKE and was unchanged with NOE and ITE. Shoulder total work was unchanged in all groups, while gross average peak torque increased by 27% with ITE and by 22% with IKE, and was unchanged with NOE. Thus, while ITE training can maintain some isokinetic functions during BR, maximal intermittent IKE training can increase other functions above pre-BR control levels.
Zheng, Xinyan; Hasegawa, Hiroshi
Dopamine (DA) has been widely investigated for its potential role in determining exercise performance. It was originally thought that DA's ergogenic effect was by mediating psychological responses. Recently, some studies have also suggested that DA may regulate physiological responses, such as thermoregulation. Hyperthermia has been demonstrated as an important limiting factor during endurance exercise. DA is prominent in the thermoregulatory centre, and changes in DA concentration have been shown to affect core temperature regulation during exercise. Some studies have proposed that DA or DA/noradrenaline (NA) reuptake inhibitors can improve exercise performance, despite hyperthermia during exercise in the heat. DA/NA reuptake inhibitors also increase catecholamine release in the thermoregulatory centre. Intracerebroventricularly injected DA has been shown to improve exercise performance through inhibiting hyperthermia-induced fatigue, even at normal ambient temperatures. Further, caffeine has been reported to increase DA release in the thermoregulatory centre and improves endurance exercise performance despite increased core body temperature. Taken together, DA has been shown to have ergogenic effects and increase heat storage and hyperthermia tolerance. The mechanisms underlying these effects seem to involve limiting/overriding the inhibitory signals from the central nervous system that result in cessation of exercise due to hyperthermia.
Background Endurance exercise capacity diminishes under hot environmental conditions. Time to exhaustion can be increased by lowering body temperature prior to exercise (pre-cooling). This systematic literature review synthesizes the current findings of the effects of pre-cooling on endurance exercise performance, providing guidance for clinical practice and further research. Methods The MEDLINE, EMBASE, CINAHL, Web of Science and SPORTDiscus databases were searched in May 2012 for studies evaluating the effectiveness of pre-cooling to enhance endurance exercise performance in hot environmental conditions (≥ 28°C). Studies involving participants with increased susceptibility to heat strain, cooling during or between bouts of exercise, and protocols where aerobic endurance was not the principle performance outcome were excluded. Potential publications were assessed by two independent reviewers for inclusion and quality. Means and standard deviations of exercise performance variables were extracted or sought from original authors to enable effect size calculations. Results In all, 13 studies were identified. The majority of studies contained low participant numbers and/or absence of sample size calculations. Six studies used cold water immersion, four crushed ice ingestion and three cooling garments. The remaining study utilized mixed methods. Large heterogeneity in methodological design and exercise protocols was identified. Effect size calculations indicated moderate evidence that cold water immersion effectively improved endurance performance, and limited evidence that ice slurry ingestion improved performance. Cooling garments were ineffective. Most studies failed to document or report adverse events. Low participant numbers in each study limited the statistical power of certain reported trends and lack of blinding could potentially have introduced either participant or researcher bias in some studies. Conclusions Current evidence indicates cold water
Burk, Andres; Timpmann, Saima; Kreegipuu, Kairi; Tamm, Maria; Unt, Eve; Oöpik, Vahur
We examined the effect of heat acclimation (HA) on endurance capacity and blood prolactin (PRL) response to moderate intensity exercise in the heat in young male subjects (n = 21). Three exercise tests (ET) were completed on a treadmill: H1 (walk at 60% VO(2)peak until exhaustion at 42°C), N (walk at 22°C; duration equal to H1) and H2 (walk until exhaustion at 42°C after a 10-day HA program). Heart rate (HR), skin (T (sk)) and core (T (c)) temperatures and body heat storage (HS) were measured. Blood samples were taken immediately before, during and immediately after each ET. HA resulted in lower HR, T (sk), T (c) and HS rate (P < 0.05) during ET, whereas endurance capacity increased from 88.6 ± 27.5 min in H1 to 162.0 ± 47.8 min in H2 (P < 0.001). Blood PRL concentration was lower (P < 0.05) during exercise in H2 compared to H1 but the peak PRL level observed at the time of exhaustion did not differ in the two trials. Blood PRL concentration at 60 min of exercise in H1 correlated with time to exhaustion in H1 (r = -0.497, P = 0.020) and H2 (r = -0.528, P = 0.014). In conclusion, HA slows down the increase in blood PRL concentration but does not reduce the peak PRL level occurring at the end of exhausting endurance exercise in the heat. Blood PRL response to exercise in the heat in non-heat-acclimated subjects is associated with their endurance capacity in the heat in a heat-acclimated state.
Choi, Sung-Keun; Baek, Seung-Hui; Choi, Seung-Wook
The purpose of this study was to find the effect of endurance training and thiamine supplementation on anti-fatigue during the exercise. Each nine students from K Women’s University went through three cross-over treatments: placebo treatment, training treatment and thiamine treatment. Training treatment was performed with bicycle ergometer exercise for four weeks (five days per week). Each exercise was performed for an hour with intensity set at 70% (50rpm) of maximal oxygen uptake. Thiamine treatment group was given 10mg of thiamine tetrahydrofurfuryl disulfide per one kilogram for four weeks. The bicycle ergometer exercise was performed at 70% of maximal oxygen uptake in exercise intensity which 60 minutes of exercise was performed at 50rpm . Lactate concentration was significantly decreased during 15 to 30 minutes of exercise for those with training treatment and 15 to 60 minutes of exercise for those with thiamine treatment compared to placebo treatment group. Ammonia concentration was significantly decreased during 15 to 60 minutes of exercise and 15 to 30 minutes of recovery for those with training and thiamine treatment compared to placebo treatment. Resting blood thiamine concentrations of placebo treatment were significantly lower than training treatment. 60 minutes after the exercise, plasma thiamine concentration was significantly increased in all treatment group. To sum up the previous, thiamine intake during exercise positively benefits carbohydrate metabolism in a way that will decrease lactate concentration, ammonia concentration, and anti- fatigue by reducing the RPE. Therefore, we can consider thiamine intake to be utilized as similar benefits as endurance training. PMID:25566430
Chen, Ya-jun; Wong, Stephen Heung-sang; Wong, Chun-kwok; Lam, Ching-Wan; Huang, Ya-jun; Siu, Parco Ming-fai
This study examined the effect of a pre-exercise meal with different glycaemic index (GI) and glycaemic load (GL) on immune responses to an endurance performance run. Eight men completed a preloaded 1 h run at 70 % VO2max on a level treadmill followed by a 10 km performance run on three occasions. In each trial, one of the three prescribed isoenergetic meals, i.e. high GI and high GL (H-H), high GI and low GL (H-L), or low GI and low GL (L-L) was consumed by the subjects 2 h before exercise. Carbohydrate intake (% of energy intake), GI, and GL were 65 %, 79.5, and 82.4 for H-H; 36 %, 78.5, and 44.1 for H-L; 65 %, 40.2, and 42.1 for L-L, respectively. The running time for the three trials was approximately 112 min at 70 % VO2max for the first hour and 76 % VO2max for the last 52 min. Consumption of pre-exercise high-carbohydrate meals (H-H and L-L) resulted in less perturbation of the circulating numbers of leucocytes, neutrophils and T lymphocyte subsets, and in decreased elevation of the plasma IL-6 concentrations immediately after exercise and during the 2 h recovery period compared with the H-L trial. These responses were accompanied by an attenuated increase in plasma IL-10 concentrations at the the end of the 2 h recovery period. The amount of carbohydrate consumed in the pre-exercise meal may be the most important influencing factor rather than the type of carbohydrate in modifying the immunoendocrine response to prolonged exercise.
Philp, Andrew; Schenk, Simon; Perez-Schindler, Joaquin; Hamilton, D Lee; Breen, Leigh; Laverone, Erin; Jeromson, Stewart; Phillips, Stuart M; Baar, Keith
Abstract The present study aimed to investigate the role of the mechanistic target of rapamycin complex 1 (mTORC1) in the regulation of myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis following endurance exercise. Forty-two female C57BL/6 mice performed 1 h of treadmill running (18 m min−1; 5° grade), 1 h after i.p. administration of rapamycin (1.5 mg · kg−1) or vehicle. To quantify skeletal muscle protein fractional synthesis rates, a flooding dose (50 mg · kg−1) of l-[ring-13C6]phenylalanine was administered via i.p. injection. Blood and gastrocnemius muscle were collected in non-exercised control mice, as well as at 0.5, 3 and 6 h after completing exercise (n = 4 per time point). Skeletal muscle MyoPS and MitoPS were determined by measuring isotope incorporation in their respective protein pools. Activation of the mTORC1-signalling cascade was measured via direct kinase activity assay and immunoblotting, whereas genes related to mitochondrial biogenesis were measured via a quantitative RT-PCR. MyoPS increased rapidly in the vehicle group post-exercise and remained elevated for 6 h, whereas this response was transiently blunted (30 min post-exercise) by rapamycin. By contrast, MitoPS was unaffected by rapamycin, and was increased over the entire post-exercise recovery period in both groups (P < 0.05). Despite rapid increases in both MyoPS and MitoPS, mTORC1 activation was suppressed in both groups post-exercise for the entire 6 h recovery period. Peroxisome proliferator activated receptor-γ coactivator-1α, pyruvate dehydrogenase kinase 4 and mitochondrial transcription factor A mRNA increased post-exercise (P < 0.05) and this response was augmented by rapamycin (P < 0.05). Collectively, these data suggest that endurance exercise stimulates MyoPS and MitoPS in skeletal muscle independently of mTORC1 activation. Key points Previous studies have shown that endurance exercise increases myofibrillar (MyoPS) and
Wilhelm, Eurico Nestor; Rech, Anderson; Minozzo, Felipe; Botton, Cintia Ehlers; Radaelli, Regis; Teixeira, Bruno Costa; Reischak-Oliveira, Alvaro; Pinto, Ronei Silveira
Concurrent training is an effective method for increasing skeletal muscle performance in aging individuals, but controversy exists as to whether chronic neuromuscular and functional adaptations are affected by the intra-session exercise sequence. Therefore the aim of this study was to evaluate the effect of concurrent endurance and power-like strength training exercise sequence on muscular and functional adaptations of older participants. Thirty-six healthy older men not engaged in systematic exercise training programs for at least 6 months were divided into a control group (CON; 65.8±5.3 years), or in the training groups: endurance-strength (ES; 63.2±3.3 years), or strength-endurance (SE; 67.1±6.1 years). Training groups underwent 12 weeks of concurrent endurance and power-like strength training, starting every exercise session with either endurance (in ES) or strength (in SE) exercises. Measurements included knee extension one repetition maximum (1RM), knee extension power, 30 second sit-to-stand test (30SS), maximum vastus lateralis surface electromyographic activity, and rectus femoris echo intensity (RFEI). Significant increases in maximal strength (ES +18±11.3%; SE +14.2±6.0%; p≤0.05), peak power (ES +22.2±19.4%; SE +26.3±31.3%; p≤0.05), and 30SS performance (ES +15.2±7.2%; SE +13.2±11.8%; p≤0.05) were observed only in the training groups, with no differences between ES and SE. Maximum muscular activity was greater after 12weeks at training groups (p≤0.05), and reductions in RFEI were found only in ES and SE (p≤0.05). These results demonstrate that concurrent strength and endurance training performed twice a week effectively increases muscular performance and functional capacity in older men, independent of the intra-session exercise sequence. Additionally, the RFEI decreases indicate an additional adaptation to concurrent training.
Muraki, Ayako; Miyashita, Kazutoshi; Mitsuishi, Masanori; Tamaki, Masanori; Tanaka, Kumiko; Itoh, Hiroshi
Statins are cholesterol-lowering drugs widely used in the prevention of cardiovascular diseases; however, they are associated with various types of myopathies. Statins inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and thus decrease biosynthesis of low-density lipoprotein cholesterol and may also reduce ubiquinones, essential coenzymes of a mitochondrial electron transport chain, which contain isoprenoid residues, synthesized through an HMG-CoA reductase-dependent pathway. Therefore, we hypothesized that statin treatment might influence physical performance through muscular mitochondrial dysfunction due to ubiquinone deficiency. The effect of two statins, atorvastatin and pravastatin, on ubiquinone content, mitochondrial function, and physical performance was examined by using statin-treated mice. Changes in energy metabolism in association with statin treatment were studied by using cultured myocytes. We found that atorvastatin-treated mice developed muscular mitochondrial dysfunction due to ubiquinone deficiency and a decrease in exercise endurance without affecting muscle mass and strength. Meanwhile, pravastatin at ten times higher dose of atorvastatin had no such effects. In cultured myocytes, atorvastatin-related decrease in mitochondrial activity led to a decrease in oxygen utilization and an increase in lactate production. Conversely, coenzyme Q(10) treatment in atorvastatin-treated mice reversed atorvastatin-related mitochondrial dysfunction and a decrease in oxygen utilization, and thus improved exercise endurance. Atorvastatin decreased exercise endurance in mice through mitochondrial dysfunction due to ubiquinone deficiency. Ubiquinone supplementation with coenzyme Q(10) could reverse atorvastatin-related mitochondrial dysfunction and decrease in exercise tolerance.
Menêses, Annelise Lins; Forjaz, Cláudia Lúcia de Moraes; de Lima, Paulo Fernando Marinho; Batista, Rafael Marinho Falcão; Monteiro, Maria de Fátima; Ritti-Dias, Raphael Mendes
The study aims to evaluate the effects of the order of endurance and resistance exercises on postexercise blood pressure (BP) and hemodynamics in hypertensive women. Nineteen hypertensive women underwent 3 sessions: control (50 minutes rest), endurance (50-60% of heart rate reserve) followed by resistance exercise (50% of 1 repetition maximum) (E + R), and resistance followed by endurance exercise (R + E). Before and 30 minutes after each session, BP, peripheral vascular resistance, cardiac output, stroke volume, and heart rate were measured. Postexercise increases in systolic (E + R: +1 ± 3 mm Hg and R + E: +3 ± 3 mm Hg), diastolic (E + R: +3 ± 1 mm Hg and R + E: +3 ± 2 mm Hg), and mean BP (E + R: +3 ± 1 mm Hg and R + E: +3 ± 2 mm Hg) were significantly lower after the exercise sessions compared with the control session (p ≤ 0.05). The exercise sessions abolished the increases in peripheral vascular resistance (E + R: +0.00 ± 0.04 mm Hg·min·L and R + E: +0.05 ± 0.05 mm Hg·min·L) and the decreases in cardiac output (E + R: +0.04 ± 0.28 L·min and R + E: -0.26 ± 0.28 L·min) observed after the control session (p ≤ 0.05). After the exercise sessions, stroke volume decreased (E + R: -14 ± 3 ml and R + E: -9 ± 4 ml) and heart rate increased (E + R: +5 ± 1 b·min and R + E: +4 ± 1 b·min) in comparison with the control session (p ≤ 0.05). For all the variables, there were no significant differences between the exercise sessions. Regardless of the order of endurance and resistance exercises, combined exercise sessions abolished increases in BP observed in a control condition due to a reduction in peripheral vascular resistance and increases in cardiac output. Thus, combined exercises should be prescribed to individuals with hypertension to control their BP, regardless of the order they are accomplished.
Conner, Jennifer D; Wolden-Hanson, Tami; Quinn, LeBris S
Using laboratory mouse models, the molecular pathways responsible for the metabolic benefits of endurance exercise are beginning to be defined. The most common method for assessing exercise endurance in mice utilizes forced running on a motorized treadmill equipped with a shock grid. Animals who quit running are pushed by the moving treadmill belt onto a grid that delivers an electric foot shock; to escape the negative stimulus, the mice return to running on the belt. However, avoidance behavior and psychological stress due to use of a shock apparatus can interfere with quantitation of running endurance, as well as confound measurements of postexercise serum hormone and cytokine levels. Here, we demonstrate and validate a refined method to measure running endurance in naïve C57BL/6 laboratory mice on a motorized treadmill without utilizing a shock grid. When mice are preacclimated to the treadmill, they run voluntarily with gait speeds specific to each mouse. Use of the shock grid is replaced by gentle encouragement by a human operator using a tongue depressor, coupled with sensitivity to the voluntary willingness to run on the part of the mouse. Clear endpoints for quantifying running time-to-exhaustion for each mouse are defined and reflected in behavioral signs of exhaustion such as splayed posture and labored breathing. This method is a humane refinement which also decreases the confounding effects of stress on experimental parameters.
McConell, G; Kloot, K; Hargreaves, M
This study compared the effects of carbohydrate ingestion throughout exercise with ingestion of an equal amount of carbohydrate late in exercise. Eight well-trained men cycled 2 h at 70 +/- 1% VO2 peak, followed immediately by a 15-min performance ride, while ingesting either a 7% carbohydrate-electrolyte solution (CHO-7), an artificially sweetened placebo (CON), or the placebo for the first 90 min then a 21% glucose solution (CHO-0/21). At the start of the performance ride, plasma glucose averaged 4.2 +/- 0.2, 5.2 +/- 0.1, and 5.7 +/- 0.2 mmol.l-1 in CON, CHO-7, and CHO-0/21, respectively (all different, P < 0.05). Plasma insulin levels were similar just prior to the performance ride in CHO-7 and CHO-0/21, with both higher than CON. A similar pattern was observed with respiratory exchange ratio (RER). Work performed during the performance ride was significantly greater in CHO-7 (268 +/- 8 kJ) compared with CON (242 +/- 9 kJ). Performance in CHO-0/21 (253 +/- 10 kJ), however, was not improved compared with CON, despite higher plasma glucose levels and plasma insulin levels similar to CHO-7. Seven of the eight subjects performed best in CHO-7. In conclusion, performance was improved, relative to the control trial, only when carbohydrate was ingested throughout exercise. Carbohydrate ingestion late in exercise did not improve performance despite increases in plasma glucose and insulin.
Stefanetti, Renae J; Lamon, Séverine; Wallace, Marita; Vendelbo, Mikkel H; Russell, Aaron P; Vissing, Kristian
Knowledge on the effects of divergent exercise on ostensibly protein degradation pathways may be valuable for counteracting muscle wasting and for understanding muscle remodelling. This study examined mRNA and/or protein levels of molecular markers of the ubiquitin proteasome pathway (UPP), including FBXO32 (atrogin-1), MURF-1, FBXO40, FOXO1 and FOXO3. Protein substrates of atrogin-1-including EIF3F, MYOG and MYOD1-and of MURF-1-including PKM and MHC-were also measured. Subjects completed 10 weeks of endurance training (ET) or resistance training (RT) followed by a single-bout of endurance exercise (EE) or resistance exercise (RE). Following training, atrogin-1, FBXO40, FOXO1 and FOXO3 mRNA increased independently of exercise mode, whereas MURF-1 mRNA and FOXO3 protein increased following ET only. No change in other target proteins occurred post-training. In the trained state, single-bout EE, but not RE, increased atrogin-1, MURF-1, FBXO40, FOXO1, FOXO3 mRNA and FOXO3 protein. In contrast to EE, FBXO40 mRNA and protein decreased following single-bout RE. MURF-1 and FOXO1 protein levels as well as the protein substrates of atrogin-1 and MURF-1 were unchanged following training and single-bout exercise. This study demonstrates that the intracellular signals elicited by ET and RT result in an upregulation of UPP molecular markers, with a greater increase following ET. However, in the trained state, the expression levels of UPP molecular markers are increased following single-bout EE, but are less responsive to single-bout RE. This suggests that adaptations following endurance exercise training are more reliant on protein UPP degradation processes than adaptations following resistance exercise training.
Nogusa, Yoshihito; Mizugaki, Ami; Hirabayashi-Osada, Yuri; Furuta, Chie; Ohyama, Kana; Suzuki, Katsuya; Kobayashi, Hisamine
Carbohydrate supplementation is extremely important during prolonged exercise because it maintains blood glucose levels during later stages of exercise. In this study, we examined whether maintaining blood glucose levels by carbohydrate supplementation could be enhanced during long-term exercise by combining this supplementation with alanine and proline, which are gluconeogenic amino acids, and whether such a combination would affect exercise endurance performance. Male C57BL/6J mice were orally administered either maltodextrin (1.25 g/kg) or maltodextrin (1.0 g/kg) with alanine (0.225 g/kg) and proline (0.025 g/kg) 15 min before running for 170 min. Combined supplementation of maltodextrin, alanine, and proline induced higher blood glucose levels than isocaloric maltodextrin alone during the late exercise phase (100-170 min). The hepatic glycogen content of mice administered maltodextrin, alanine, and proline was higher than that of mice ingesting maltodextrin alone 60 min after beginning exercise, but the glycogen content of the gastrocnemius muscle showed no difference. We conducted a treadmill running test to determine the effect of alanine and proline on endurance performance. The test showed that running time to exhaustion of mice that were supplemented with maltodextrin (2.0 g/kg) was longer than that of mice that were supplemented with water alone. Maltodextrin supplementation (1.0 g/kg) with alanine (0.9 g/kg) and proline (0.1 g/kg) further increased running time to exhaustion compared to maltodextrin alone (2.0 g/kg). These results indicate that combined supplementation of carbohydrate, alanine, and proline is effective for maintaining blood glucose and hepatic glycogen levels and increasing endurance performance during long-term exercise in mice.
Younes, Mohamed; Robert, Céline; Barrey, Eric; Cottin, François
Although cardiac recovery is an important criterion for ranking horses in endurance competitions, heart rate variability (HRV) has hardly ever been studied in the context of this equestrian discipline. In the present study, we sought to determine whether HRV is affected by parameters such as age, exercise duration and test site. Accordingly, HRV might be used to select endurance horses with the fastest cardiac recovery. The main objective of the present study was to determine the effects of age, exercise duration, and test site on HRV variables at rest and during exercise and recovery in young Arabian endurance horses. Over a 3-year period, 77 young Arabian horses aged 4-6 years performed one or more exercise tests (consisting of a warm-up, cantering at 22 km.h(-1)and a final 500 m gallop at full speed) at four different sites. Beat-to-beat RR intervals were continuously recorded and then analyzed (using a time-frequency approach) to determine the instantaneous HRV components before, during and after the test. At rest, the root-mean-square of successive differences in RR intervals (RMSSD) was higher in the 4-year-olds (54.4 ± 14.5 ms) than in the 5-or 6-year-olds (44.9 ± 15.5 and 49.1 ± 11.7 ms, respectively). During the first 15 min of exercise (period T), the heart rate (HR) and RMSSD decreased with age. In 6-year-olds, RMSSD decreased as the exercise duration increased (T: 3.0 ± 1.4 vs. 2T: 3.6 ± 2.2 vs. 3T: 2.8 ± 1.0). During recovery, RMSSD was negatively correlated with the cardiac recovery time (CRT) and the recovery heart rate (RHR; R = -0.56 and -0.53, respectively; p < 0.05). At rest and during exercise and recovery, RMSSD and several HRV variables differed significantly as a function of the test conditions. HRV in endurance horses appears to be strongly influenced by age and environmental factors (such as ambient temperature, ambient humidity, and track quality). Nevertheless, RMSSD can be used to select endurance horses with the fastest cardiac
Younes, Mohamed; Robert, Céline; Barrey, Eric; Cottin, François
Although cardiac recovery is an important criterion for ranking horses in endurance competitions, heart rate variability (HRV) has hardly ever been studied in the context of this equestrian discipline. In the present study, we sought to determine whether HRV is affected by parameters such as age, exercise duration and test site. Accordingly, HRV might be used to select endurance horses with the fastest cardiac recovery. The main objective of the present study was to determine the effects of age, exercise duration, and test site on HRV variables at rest and during exercise and recovery in young Arabian endurance horses. Over a 3-year period, 77 young Arabian horses aged 4–6 years performed one or more exercise tests (consisting of a warm-up, cantering at 22 km.h−1and a final 500 m gallop at full speed) at four different sites. Beat-to-beat RR intervals were continuously recorded and then analyzed (using a time-frequency approach) to determine the instantaneous HRV components before, during and after the test. At rest, the root-mean-square of successive differences in RR intervals (RMSSD) was higher in the 4-year-olds (54.4 ± 14.5 ms) than in the 5-or 6-year-olds (44.9 ± 15.5 and 49.1 ± 11.7 ms, respectively). During the first 15 min of exercise (period T), the heart rate (HR) and RMSSD decreased with age. In 6-year-olds, RMSSD decreased as the exercise duration increased (T: 3.0 ± 1.4 vs. 2T: 3.6 ± 2.2 vs. 3T: 2.8 ± 1.0). During recovery, RMSSD was negatively correlated with the cardiac recovery time (CRT) and the recovery heart rate (RHR; R = −0.56 and −0.53, respectively; p < 0.05). At rest and during exercise and recovery, RMSSD and several HRV variables differed significantly as a function of the test conditions. HRV in endurance horses appears to be strongly influenced by age and environmental factors (such as ambient temperature, ambient humidity, and track quality). Nevertheless, RMSSD can be used to select endurance horses with the fastest
Oueslati, Ferid; Boone, Jan; Ahmaidi, Said
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.
Juan-Recio, C; López-Vivancos, A; Moya, M; Sarabia, J M; Vera-Garcia, F J
Despite core exercise programs are broadly used to increase muscle function and to promote low back health, there is a lack of scientific evidence on some of the most important characteristics of trunk exercise programs, as for example training frequency. This study aimed to compare the short-term effect of training frequencies of 1, 2 and 3 days per week (d/wk) on abdominal muscle endurance in untrained adolescents. One hundred and eighteen high-school students (59 men and 59 women) with no previous experience in structured abdominal exercise programs were assigned randomly to groups that trained 1 d/wk (G1; N.=21), 2 d/wk (G2; N.=27), 3 d/wk (G3; N.=23), or to a control group (CG; N.=47) that did not train. The training groups performed crunch and cross-crunch exercises 1, 2 or 3 d/wk during six weeks. Before and after the training period, the bench trunk-curl test (BTC test) was carried out to assess abdominal muscle endurance. Men obtained higher BTC test scores than women before and after training. Training frequencies of 1, 2 and 3 d/wk provided a significant increase in BTC test scores; however, no significant differences between the three groups' scores were found after training. Therefore, a small dose of crunch exercise training (1 d/wk) may be sufficient stimulus to increase abdominal endurance in untrained male and female adolescents, at least during the first weeks of an abdominal exercise program, which seems a very relevant finding in terms of time-cost efficiency.
Igwebuike, Ada; Irving, Brian A.; Bigelow, Maureen L.; Short, Kevin R.; McConnell, Joseph P.; Nair, K. Sreekumaran
Context: Recent studies disputed the widely promoted anti-aging effect of dehydroepiandrosterone (DHEA) supplementation; however, conflicting data exist on whether physiological DHEA supplementation enhances exercise training effects on body composition, physical performance, and cardiometabolic risk in healthy postmenopausal women. Objective: The aim of this study was to determine whether 12 wk of DHEA supplementation (50 mg/d) in postmenopausal women enhances exercise-related changes in body composition, physical performance, and cardiometabolic risk. Design and Setting: This study was a 12-wk randomized double-blind, placebo-controlled trial and took place at the Mayo Clinic General Clinical Research Center (Rochester, MN). Participants: Thirty-one sedentary, postmenopausal, Caucasian women (mean ± sem age 64.6 ± 1.0 yr) completed the study. Intervention: Participants were randomized to one of two 12-wk interventions: 1) exercise training plus 50 mg/d of DHEA (n = 17), or 2) exercise training plus placebo (n = 14). The exercise intervention consisted of both endurance (4 d/wk) and resistance (3 d/wk) exercise components. Main Outcome Measures: The main outcomes were measures of body composition, physical performance, and measures of cardiometabolic risk. Results: DHEA treatment with exercise resulted in increases in circulating sulfated DHEA (650%), total testosterone (100%), estradiol (165%), estrone (85%), and IGF-I (30%) (all P ≤ 0.05, for all within and between treatment comparisons). Although exercise training alone significantly improved physical performance, body composition, and insulin sensitivity, administration of DHEA provided no additional benefits. Conclusions: Twelve weeks of combined endurance and resistance training significantly improved body composition, physical performance, insulin sensitivity, and low-density lipoprotein cholesterol particle number and size, whereas DHEA had no additional benefits. PMID:18029465
Hung, Yu‐Han; Linden, Melissa A.; Gordon, Alicia; Scott Rector, R.; Buhman, Kimberly K.
Abstract Endurance exercise has been shown to improve metabolic outcomes in obesity and type 2 diabetes; however, the physiological and molecular mechanisms for these benefits are not completely understood. Although endurance exercise has been shown to decrease lipogenesis, promote fatty acid oxidation (FAO), and increase mitochondrial biosynthesis in adipose tissue, muscle, and liver, its effects on intestinal lipid metabolism remain unknown. The absorptive cells of the small intestine, enterocytes, mediate the highly efficient absorption and processing of nutrients, including dietary fat for delivery throughout the body. We investigated how endurance exercise altered intestinal lipid metabolism in obesity and type 2 diabetes using Otsuka Long‐Evans Tokushima Fatty (OLETF) rats. We assessed mRNA levels of genes associated with intestinal lipid metabolism in nonhyperphagic, sedentary Long‐Evans Tokushima Otsuka (LETO) rats (L‐Sed), hyperphagic, sedentary OLETF rats (O‐Sed), and endurance exercised OLETF rats (O‐EndEx). O‐Sed rats developed hyperphagia‐induced obesity (HIO) and type 2 diabetes compared with L‐Sed rats. O‐EndEx rats gained significantly less weight and fat pad mass, and had improved serum metabolic parameters without change in food consumption compared to O‐Sed rats. Endurance exercise resulted in dramatic up‐regulation of a number of genes in intestinal lipid metabolism and mitochondrial content compared with sedentary rats. Overall, this study provides evidence that endurance exercise programs intestinal lipid metabolism, likely contributing to its role in improving metabolic outcomes in obesity and type 2 diabetes. PMID:25602012
Hung, Yu-Han; Linden, Melissa A; Gordon, Alicia; Rector, R Scott; Buhman, Kimberly K
Endurance exercise has been shown to improve metabolic outcomes in obesity and type 2 diabetes; however, the physiological and molecular mechanisms for these benefits are not completely understood. Although endurance exercise has been shown to decrease lipogenesis, promote fatty acid oxidation (FAO), and increase mitochondrial biosynthesis in adipose tissue, muscle, and liver, its effects on intestinal lipid metabolism remain unknown. The absorptive cells of the small intestine, enterocytes, mediate the highly efficient absorption and processing of nutrients, including dietary fat for delivery throughout the body. We investigated how endurance exercise altered intestinal lipid metabolism in obesity and type 2 diabetes using Otsuka Long-Evans Tokushima Fatty (OLETF) rats. We assessed mRNA levels of genes associated with intestinal lipid metabolism in nonhyperphagic, sedentary Long-Evans Tokushima Otsuka (LETO) rats (L-Sed), hyperphagic, sedentary OLETF rats (O-Sed), and endurance exercised OLETF rats (O-EndEx). O-Sed rats developed hyperphagia-induced obesity (HIO) and type 2 diabetes compared with L-Sed rats. O-EndEx rats gained significantly less weight and fat pad mass, and had improved serum metabolic parameters without change in food consumption compared to O-Sed rats. Endurance exercise resulted in dramatic up-regulation of a number of genes in intestinal lipid metabolism and mitochondrial content compared with sedentary rats. Overall, this study provides evidence that endurance exercise programs intestinal lipid metabolism, likely contributing to its role in improving metabolic outcomes in obesity and type 2 diabetes.
Murakami, Taro Yoshinaga, Mariko
Highlights: •Regulation of amino acid transporter expression in working muscle remains unclear. •Expression of amino acid transporters for leucine were induced by a bout of exercise. •Requirement of leucine in muscle cells might regulate expression of its transporters. •This information is beneficial for understanding the muscle remodeling by exercise. -- Abstract: We here investigated whether an acute bout of endurance exercise would induce the expression of amino acid transporters that regulate leucine transport across plasma and lysosomal membranes in rat skeletal muscle. Rats ran on a motor-driven treadmill at a speed of 28 m/min for 90 min. Immediately after the exercise, we observed that expression of mRNAs encoding L-type amino acid transporter 1 (LAT1) and CD98 was induced in the gastrocnemius, soleus, and extensor digitorum longus (EDL) muscles. Sodium-coupled neutral amino acid transporter 2 (SNAT2) mRNA was also induced by the exercise in those three muscles. Expression of proton-assisted amino acid transporter 1 (PAT1) mRNA was slightly but not significantly induced by a single bout of exercise in soleus and EDL muscles. Exercise-induced mRNA expression of these amino acid transporters appeared to be attenuated by repeated bouts of the exercise. These results suggested that the expression of amino acid transporters for leucine may be induced in response to an increase in the requirement for this amino acid in the cells of working skeletal muscles.
Faes, Camille; Balayssac-Siransy, Edwige; Connes, Philippe; Hivert, Ludovic; Danho, Clotaire; Bogui, Pascal; Martin, Cyril; Pialoux, Vincent
Very few studies have investigated the effects of exercise on the biological parameters involved in vaso-occlusive events in sickle cell anaemia (SCA). The aim of this study was to test how a mild-moderate endurance exercise modulates oxidative stress, nitric oxide bioavailability and endothelial activation in SCA patients and healthy individuals. Eleven patients with SCA and 15 healthy subjects completed a 20-min duration submaximal cycling exercise at ≈45 Watts. Plasma markers of oxidative stress, antioxidant activity, endothelial activation and nitric oxide bioavailability were investigated before and after the exercise. Nitric oxide levels, anti-oxidant capacity, soluble (s)E-selectin and sP-selectin did not change in response to this exercise. Except for the malondialdehyde levels, which increased in the two groups, the other markers of oxidative stress remained unchanged in both groups in response to exercise. Soluble vascular cell adhesion molecule 1 levels were increased at the end of exercise in both groups. sL-selectin decreased and soluble intercellular adhesion molecule 1 increased with exercise in SCA patients only. The present data suggest that patients with SCA may undertake mild-moderate physical activities without any acute clinical complications, but care should be taken because oxidative stress and endothelial activation significantly increased in some patients.
Keramidas, Michail E; Debevec, Tadej; Amon, Mojca; Kounalakis, Stylianos N; Simunic, Bostjan; Mekjavic, Igor B
The aim of this study was to investigate the effect of respiratory muscle endurance training on endurance exercise performance in normoxic and hypoxic conditions. Eighteen healthy males were stratified for age and aerobic capacity; and randomly assigned either to the respiratory muscle endurance training (RMT = 9) or to the control training group (CON = 9). Both groups trained on a cycle-ergometer 1 h day(-1), 5 days per week for a period of 4 weeks at an intensity corresponding to 50% of peak power output. Additionally, the RMT group performed a 30-min specific endurance training of respiratory muscles (isocapnic hyperpnea) prior to the cycle ergometry. Pre, Mid, Post and 10 days after the end of training period, subjects conducted pulmonary function tests (PFTs), maximal aerobic tests in normoxia (VO(2max)NOR), and in hypoxia (VO(2max)HYPO; F(I)O(2) = 0.12); and constant-load tests at 80% of VO(2max)NOR in normoxia (CLT(NOR)), and in hypoxia (CLTHYPO). Both groups enhanced VO(2max)NOR (CON: +13.5%; RMT: +13.4%), but only the RMT group improved VO(2max)HYPO Post training (CON: -6.5%; RMT: +14.2%). Post training, the CON group increased peak power output, whereas the RMT group had higher values of maximum ventilation. Both groups increased CLT(NOR) duration (CON: +79.9%; RMT: +116.6%), but only the RMT group maintained a significantly higher CLT(NOR) 10 days after training (CON: +56.7%; RMT: +91.3%). CLT(HYPO) remained unchanged in both groups. Therefore, the respiratory muscle endurance training combined with cycle ergometer training enhanced aerobic capacity in hypoxia above the control values, but did not in normoxia. Moreover, no additional effect was obtained during constant-load exercise.
Amorim, Fabiano T.; Schneider, Suzanne M.; Lee, Stuart M. C.; Boda, Wanda L.; Watenpaugh, Donald E.; Hargens, Alan R.
Decreases in muscle strength and endurance frequently are observed in non-weightbearing conditions such as bed rest (BR), spaceflight or limb immobilization. Purpose: Ow purpose was to determine if supine treadmill exercise against simulated gravity, by application of lower body negative pressure (LBNP), prevents loss of lean leg mass, strength and endurance during 30 d of 6deg head-down bed rest (BR). Methods: Fifteen pairs of monozygous twins (8 male, 7 female pairs; 26+/-4 yrs; 170+/-12 cm; 62.6+/-11.3 kg; mean+/-SD) were subjects in the present study. One sibling of each pair of twins was randomly assigned to either an exercise (EX) or non-exercise (CON) group. The EX twin walked/jogged on a vertical treadmill within LBNP chamber 6 d/wk using a 40-min interval exercise protocol at 40-80% of pre-BR VO(sub 2peak). LBNP was adjusted individually for each subject such that footward force was between 1.0 and 1.2 times body weight (-53+/-5 mmHg LBNP). The CON twin performed no exercise during BR. Subjects performed isokinetic knee (60 and 120deg/s) and ankle (60deg/s) testing to assess strength and endurance (End) before and after BR. They also had their lean leg mass (L(sub mass)) evaluated by DEXA before and after BR. Results: Changes in peak torque (T(sub pk)) were smaller for flexion (flex) than for extension (ext) after BR and did not differ between groups. The CON group had larger decreases (P<0.05) in L(sub mass), knee and ankle ext T(sub pk), and knee ext End.
Sanchez, Anthony M J; Bernardi, Henri; Py, Guillaume; Candau, Robin B
Physical exercise is a stress that can substantially modulate cellular signaling mechanisms to promote morphological and metabolic adaptations. Skeletal muscle protein and organelle turnover is dependent on two major cellular pathways: Forkhead box class O proteins (FOXO) transcription factors that regulate two main proteolytic systems, the ubiquitin-proteasome, and the autophagy-lysosome systems, including mitochondrial autophagy, and the MTORC1 signaling associated with protein translation and autophagy inhibition. In recent years, it has been well documented that both acute and chronic endurance exercise can affect the autophagy pathway. Importantly, substantial efforts have been made to better understand discrepancies in the literature on its modulation during exercise. A single bout of endurance exercise increases autophagic flux when the duration is long enough, and this response is dependent on nutritional status, since autophagic flux markers and mRNA coding for actors involved in mitophagy are more abundant in the fasted state. In contrast, strength and resistance exercises preferentially raise ubiquitin-proteasome system activity and involve several protein synthesis factors, such as the recently characterized DAGK for mechanistic target of rapamycin activation. In this review, we discuss recent progress on the impact of acute and chronic exercise on cell component turnover systems, with particular focus on autophagy, which until now has been relatively overlooked in skeletal muscle. We especially highlight the most recent studies on the factors that can impact its modulation, including the mode of exercise and the nutritional status, and also discuss the current limitations in the literature to encourage further works on this topic.
Ormsbee, Michael J; Bach, Christopher W; Baur, Daniel A
Endurance athletes rarely compete in the fasted state, as this may compromise fuel stores. Thus, the timing and composition of the pre-exercise meal is a significant consideration for optimizing metabolism and subsequent endurance performance. Carbohydrate feedings prior to endurance exercise are common and have generally been shown to enhance performance, despite increasing insulin levels and reducing fat oxidation. These metabolic effects may be attenuated by consuming low glycemic index carbohydrates and/or modified starches before exercise. High fat meals seem to have beneficial metabolic effects (e.g., increasing fat oxidation and possibly sparing muscle glycogen). However, these effects do not necessarily translate into enhanced performance. Relatively little research has examined the effects of a pre-exercise high protein meal on subsequent performance, but there is some evidence to suggest enhanced pre-exercise glycogen synthesis and benefits to metabolism during exercise. Finally, various supplements (i.e., caffeine and beetroot juice) also warrant possible inclusion into pre-race nutrition for endurance athletes. Ultimately, further research is needed to optimize pre-exercise nutritional strategies for endurance performance.
Ormsbee, Michael J.; Bach, Christopher W.; Baur, Daniel A.
Endurance athletes rarely compete in the fasted state, as this may compromise fuel stores. Thus, the timing and composition of the pre-exercise meal is a significant consideration for optimizing metabolism and subsequent endurance performance. Carbohydrate feedings prior to endurance exercise are common and have generally been shown to enhance performance, despite increasing insulin levels and reducing fat oxidation. These metabolic effects may be attenuated by consuming low glycemic index carbohydrates and/or modified starches before exercise. High fat meals seem to have beneficial metabolic effects (e.g., increasing fat oxidation and possibly sparing muscle glycogen). However, these effects do not necessarily translate into enhanced performance. Relatively little research has examined the effects of a pre-exercise high protein meal on subsequent performance, but there is some evidence to suggest enhanced pre-exercise glycogen synthesis and benefits to metabolism during exercise. Finally, various supplements (i.e., caffeine and beetroot juice) also warrant possible inclusion into pre-race nutrition for endurance athletes. Ultimately, further research is needed to optimize pre-exercise nutritional strategies for endurance performance. PMID:24787031
Hyun, Ju; Kim, Young Mi; Hwangbo, Kak; Kim, Young Mi
[Purpose] The purpose of this study was to investigate the effects of exercise on muscle damage indices in male Sprague-Dawley rats. Two groups of rats were trained in either moderate- or high-intensity treadmill running for 4 weeks. Subsequently, the concentrations of creatine kinase, lactate dehydrogenase, and high-sensitivity C-reactive protein were examined following a single bout of prolonged (3-h) intensive exercise. [Subjects and Methods] The study included forty 6-week-old male Sprague-Dawley rats weighing 150–180 g each. The aerobic exercise group was divided into high-intensity (28 m/min) and moderate-intensity (15 m/min) subgroups. Both subgroups were trained for 35 min daily for 6 days per week (excluding Sunday) over a 4-week period. Following training, the high- and moderate-intensity exercise groups and a non-exercise group performed one bout of prolonged (3-h) treadmill exercise for 3 hours at a speed of 15 m/min. [Results] Creatine kinase and lactate dehydrogenase levels differed significantly among the groups. [Conclusion] The preliminary exercise groups showed lower muscle damage and inflammatory response levels than the non-exercise group after the bout of prolonged intensive exercise. PMID:27390433
Ansley, L; Marvin, G; Sharma, A; Kendall, M J; Jones, D A; Bridge, M W
The present study investigated the effects of head cooling during endurance cycling on performance and the serotonergic neuroendocrine response to exercise in the heat. Subjects exercised at 75 % VO(2max) to volitional fatigue on a cycle ergometer at an ambient temperature of 29+/-1.0 degrees C, with a relative humidity of approximately 50 %. Head cooling resulted in a 51 % (p<0.01) improvement in exercise time to fatigue and Borg Scale ratings of perceived exertion were significantly lower throughout the exercise period with cooling (p<0.01). There were no indications of peripheral mechanisms of fatigue either with, or without, head cooling, indicating the importance of central mechanisms. Exercise in the heat caused the release of prolactin in response to the rise in rectal temperature. Head cooling largely abolished the prolactin response while having no effect on rectal temperature. Tympanic temperature and sinus skin temperature were reduced by head cooling and remained low throughout the exercise. It is suggested that there is a co-ordinated response to exercise involving thermoregulation, neuroendocrine secretion and behavioural adaptations that may originate in the hypothalamus or associated areas of the brain. Our results are consistent with the effects of head cooling being mediated by both direct cooling of the brain and modified cerebral artery blood flow, but an action of peripheral thermoreceptors cannot be excluded.
Kimura, Takehide; Matsuura, Ryouta; Arimitsu, Takuma; Yunoki, Takahiro; Yano, Tokuo
The aim of this study was to determine whether the increase in blood volume in resting muscle during moderately prolonged exercise is related to heart rate (HR) upward drift. Eight healthy men completed both arm-cranking moderately prolonged exercise (APE) and leg-pedaling moderately prolonged exercise (LPE) for 30 min. Exercise intensity was 120 bpm of HR that was determined by ramp incremental exercise. During both APE and LPE, HR significantly increased from 3 to 30 min (from 108±9.3 to 119±12 bpm and from 112±8.9 to 122±11 bpm, respectively). However, there was no significant difference between HR in APE and that in LPE. Oxygen uptake was maintained throughout the two exercises. Skin blood flow, deep temperature, and total Hb (blood volume) in resting muscle continuously increased for 30 min of exercise during both APE and LPE. During both APE and LPE, there was a significant positive correlation between total Hb and deep temperature in all subjects. Moreover, there was a significant positive correlation between HR and total Hb (in seven out of eight subjects) during LPE. However, during APE, there was no positive correlation between HR and total Hb (r=0.391). These findings suggest that an increase of blood pooling in resting muscle could be proposed as one of the mechanisms underlying HR upward drift during moderately prolonged exercise.
Tachtsis, Bill; Smiles, William J.; Lane, Steven C.; Hawley, John A.; Camera, Donny M.
Purpose: The tumor suppressor protein p53 may have regulatory roles in exercise response-adaptation processes such as mitochondrial biogenesis and autophagy, although its cellular location largely governs its biological role. We investigated the subcellular localization of p53 and selected signaling targets in human skeletal muscle following a single bout of endurance exercise. Methods: Sixteen, untrained individuals were pair-matched for aerobic capacity (VO2peak) and allocated to either an exercise (EX, n = 8) or control (CON, n = 8) group. After a resting muscle biopsy, EX performed 60 min continuous cycling at ~70% of VO2peak during which time CON subjects rested. A further biopsy was obtained from both groups 3 h post-exercise (EX) or 4 h after the first biopsy (CON). Results: Nuclear p53 increased after 3 h recovery with EX only (~48%, p < 0.05) but was unchanged in the mitochondrial or cytoplasmic fractions in either group. Autophagy protein 5 (Atg-5) decreased in the mitochondrial protein fraction 3 h post-EX (~69%, P < 0.05) but remained unchanged in CON. There was an increase in cytoplasmic levels of the mitophagy marker PINK1 following 3 h of rest in CON only (~23%, P < 0.05). There were no changes in mitochondrial, nuclear, or cytoplasmic levels of PGC-1α post-exercise in either group. Conclusions: The selective increase in nuclear p53 abundance following endurance exercise suggests a potential pro-autophagy response to remove damaged proteins and organelles prior to initiating mitochondrial biogenesis and remodeling responses in untrained individuals. PMID:27199762
Coso, Juan Del; Estevez, Emma; Baquero, Raúl Antonio; Mora-Rodriguez, Ricardo
The effects that rehydrating drinks ingested during exercise may have on anaerobic exercise performance are unclear. This study aimed to determine which of four commercial rehydrating drinks better maintains leg power and force during prolonged cycling in the heat. Seven endurance-trained and heat-acclimatized cyclists pedaled for 120 min at 63% maximum oxygen consumption in a hot, dry environment (36 degrees C; 29% humidity, 1.9 m.s-1 airflow). In five randomized trials, during exercise, subjects drank 2.4 +/- 0.1 L of (i) mineral water (WAT; San Benedetto), (ii) 6% carbohydrate-electrolyte solution (Gatorade lemon), (iii) 8% carbohydrate-electrolyte solution (Powerade Citrus Charge), (iv) 8% carbohydrate-electrolyte solution with lower sodium concentration than other sports drinks (Aquarius orange), or (v) did not ingest any fluid (DEH). Fluid balance, rectal temperature (Trec), maximal cycling power (Pmax), and leg maximal voluntary isometric contraction (MVC) were measured. During DEH, subjects lost 3.7 +/- 0.2% of initial body mass, whereas subjects lost only 0.8% +/- 0.1% in the other trials (p < 0.05). Final Trec was higher in DEH than in the rest of the trials (39.4 +/- 0.1 degrees C vs. 38.7 +/- 0.1 degrees C; p < 0.05). Pmax was similar among all trials. Gatorade and Powerade preserved MVC better than DEH (-3.1% +/- 2% and -3.8% +/- 2% vs. -11% +/- 2%, p < 0.05), respectively, whereas WAT and Aquarius did not (-6% +/- 2%). Compared with DEH, rehydration with commercially available sports drinks during prolonged exercise in the heat preserves leg force, whereas rehydrating with water does not. However, low sodium concentration in a sports drink seems to preclude its ergogenic effects on force.
Walz, E; Lane, AR; Pebole, M; Hackney, AC
This study assessed the influence of estrogen (E2) on muscle damage biomarkers [skeletal muscle - creatine kinase (CK); cardiac muscle - CK-MB] responses to prolonged aerobic exercise. Eumenorrheic women (n=10) who were physically active completed two 60-minute treadmill running sessions at ∼60-65% maximal intensity during low E2 (midfollicular menstrual phase) and high E2 (midluteal menstrual phase) hormonal conditions. Blood samples were collected prior to exercise (following supine rest), immediately post-, 30 min post-, and 24 hours post-exercise to determine changes in muscle biomarkers. Resting blood samples confirmed appropriate E2 hormonal levels Total CK concentrations increased following exercise and at 24 hours post-exercise were higher in the midfollicular low E2 phase (p<0.001). However, CK-MB concentrations were unaffected by E2 level or exercise (p=0.442) resulting in the ratio of CK-MB to total CK being consistently low in subject responses (i.e., indicative of skeletal muscle damage). Elevated E2 levels reduce the CK responses of skeletal muscle, but had no effect on CK-MB responses following prolonged aerobic exercise. These findings support earlier work showing elevated E2 is protective of skeletal muscle from exercise-induced damage associated with prolonged aerobic exercise. PMID:26424921
Wu, Ching-Lin; Williams, Clyde
This study investigated the effects of ingesting a low (LGI) or high (HGI) glycemic index carbohydrate (CHO) meal 3 h prior to exercise on endurance running capacity. Eight male recreational runners undertook two trials (LGI or HGI) which were randomized and separated by 7 d. After an overnight fast (12 h) the subjects ingested either a LGI or HGI meal 3 h prior to running at 70% VO2max until exhaustion. The meals contained 2 g/kg body mass CHO and were isocaloric and iso-macronutrient with calculated GI values 77 and 37 for the HGI and LGI respectively. The run times for the LGI and HGI trials were 108.8 +/- 4.1 min and 101.4 +/- 5.2 min respectively (P = 0.038). Fat oxidation rates were higher during exercise after the LGI meal than after the HGI meal (P < 0.05). In summary, ingestion of a LGI meal 3 h before exercise resulted in a greater endurance capacity than after the ingestion of a HGI meal.
Burt, Dean; Lamb, Kevin; Nicholas, Ceri; Twist, Craig
It is well established that exercise-induced muscle damage (EIMD) has a detrimental effect on endurance exercise performed in the days that follow. However, it is unknown whether such effects remain after a repeated bout of EIMD. Therefore, the purpose of this study was to examine the effects of repeated bouts of muscle-damaging exercise on sub-maximal running exercise. Nine male participants completed baseline measurements associated with a sub-maximal running bout at lactate turn point. These measurements were repeated 24-48 h after EIMD, comprising 100 squats (10 sets of 10 at 80 % body mass). Two weeks later, when symptoms from the first bout of EIMD had dissipated, all procedures performed at baseline were repeated. Results revealed significant increases in muscle soreness and creatine kinase activity and decreases in peak knee extensor torque and vertical jump performance at 24-48 h after the initial bout of EIMD. However, after the repeated bout, symptoms of EIMD were reduced from baseline at 24-48 h. Significant increases in oxygen uptake (.VO2), minute ventilation (.VE), blood lactate ([BLa]), rating of perceived exertion (RPE), stride frequency and decreases in stride length were observed during sub-maximal running at 24-48 h following the initial bout of EIMD. However, following the repeated bout of EIMD, .VO2, .VE, [BLa], RPE and stride pattern responses during sub-maximal running remained unchanged from baseline at all time points. These findings confirm that a single resistance session protects skeletal muscle against the detrimental effects of EIMD on sub-maximal running endurance exercise.
Davitt, Patrick M; Arent, Shawn M; Tuazon, Marc A; Golem, Devon L; Henderson, Gregory C
We investigated the effects of two exercise modalities on postprandial triglyceride (TG) and free fatty acid (FFA) metabolism. Sedentary, obese women were studied on three occasions in randomized order: endurance exercise for 60 min at 60-65% aerobic capacity (E), ~60 min high-intensity resistance exercise (R), and a sedentary control trial (C). After exercise, a liquid-mixed meal containing [U-(13)C]palmitate was consumed, and subjects were studied over 7 h. Isotopic enrichment (IE) of plasma TG, plasma FFA, and breath carbon dioxide compared with meal IE indicated the contribution of dietary fat to each pool. Total and endogenously derived plasma TG content was reduced significantly in both E and R compared with C (P < 0.05), with no effect of exercise on circulating exogenous (meal-derived) TG content. Exogenous plasma FFA content was increased significantly following both E and R compared with C (P < 0.05), whereas total and endogenous FFA concentrations were elevated only in E (P < 0.05) compared with C. Fatty acid (FA) oxidation rates were increased significantly after E and R compared with C (P < 0.05), with no difference between exercise modalities. The present results indicate that E and R may be equally effective in reducing postprandial plasma TG concentration and enhancing lipid oxidation when the exercise sessions are matched for duration rather than for energy expenditure. Importantly, tracer results indicated that the reduction in postprandial lipemia after E and R exercise bouts is not achieved by enhanced clearance of dietary fat but rather, is achieved by reduced abundance of endogenous FA in plasma TG.
Farella, Mauro; Bakke, Merete; Michelotti, Ambra; Rapuano, Alessia; Martina, Roberto
The aim of the study was to compare neuromuscular features of the masseter muscle in subjects with different vertical craniofacial morphology. Fifteen short-faced (mandibular plane-Frankfurt plane angle < 15 degrees) and 15 normal- to long-faced (mandibular plane-Frankfurt plane angle > or = 23 degrees) male students participated. The thickness of the masseter was assessed by ultrasonography. Onset and endurance of exercise pain were recorded during sustained biting at a level of 15% of maximum voluntary contraction and 30 micro V electromyographic activity. Pain and fatigue was measured on visual analog scales before and after the biting, as well as before and after 10 min chewing. Statistical comparison showed that the masseter muscle was significantly thicker (+15%) in the short-faced than the normal- to long-faced subjects. The pain onset time and endurance time were also consistently shorter in short-faced subjects, whereas the intensity of pain and fatigue did not differ significantly between the two groups. Multiple stepwise regression showed positive influence from the mandibular plane inclination and the masseter thickness on the pain onset time and endurance time. The present findings support the concept that subjects with different craniofacial morphology show neuromuscular differences.
Arai, Aki; Hirota, Yu; Miyase, Naoki; Miyata, Shiori; Young, Larry J; Osako, Yoji; Yuri, Kazunari; Mitsui, Shinichi
Traumatic events such as natural disasters, violent crimes, tragic accidents, and war, can have devastating impacts on social relationships, including marital partnerships. We developed a single prolonged stress (SPS) paradigm, which consisted of restraint, forced swimming, and ether anesthesia, to establish an animal model relevant to post-traumatic stress disorder. We applied a SPS paradigm to a monogamous rodent, the prairie vole (Microtus ochrogaster) in order to determine whether a traumatic event affects the establishment of pair bonds. We did not detect effects of the SPS treatment on anhedonic or anxiety-like behavior. Sham-treated male voles huddled with their partner females, following a 6day cohabitation, for a longer duration than with a novel female, indicative of a pair bond. In contrast, SPS-treated voles indiscriminately huddled with the novel and partner females. Interestingly, the impairment of pair bonding was rescued by oral administration of paroxetine, a selective serotonin reuptake inhibitor (SSRI), after the SPS treatment. Immunohistochemical analyses revealed that oxytocin immunoreactivity (IR) was significantly decreased in the supraoptic nucleus (SON), but not in the paraventricular nucleus (PVN), 7days after SPS treatment, and recovered 14days after SPS treatment. After the presentation of a partner female, oxytocin neurons labeled with Fos IR was significantly increased in SPS-treated voles compared with sham-treated voles regardless of paroxetine administration. Our results suggest that traumatic events disturb the formation of pair bond possibly through an interaction with the serotonergic system, and that SSRIs are candidates for the treatment of social problems caused by traumatic events. Further, a vole SPS model may be useful for understanding mechanisms underlying the impairment of social bonding by traumatic events.
Doutreleau, Stéphane; Pistea, Cristina; Lonsdorfer, Evelyne; Charloux, Anne
Training induces volume- and time-dependent morphological and functional changes in the heart. Heart rhythm disorders, such as atrial arrhythmia (including atrial fibrillation and atrial flutter), are a well-established consequence of such long-term endurance practice. Although resting bradycardia and first-degree atrioventricular persist in veteran athletes, a higher conduction system impairment has never been reported neither at rest nor during exercise. We report here two cases of Type II second-degree atrioventricular block occurring during exercise in middle-age well-trained athletes. Because animal and human studies suggest that a progressive myocardial fibrosis could explain such phenomenon, long-term training could also have consequences on the conduction pathways.
Sinoway, L.; Shenberger, J.; Leaman, G.; Zelis, R.; Gray, K.; Baily, R.; Leuenberger, U.
We previously demonstrated that nonfatiguing rhythmic forearm exercise at 25% maximal voluntary contraction (12 2-s contractions/min) evokes sympathoexcitation without significant engagement of metabolite-sensitive muscle afferents (B.A. Batman, J.C. Hardy, U.A. Leuenberger, M.B. Smith, Q.X. Yang and L.I. Sinoway. J. Appl. Physiol. 76: 1077-1081, 1994). This is in contrast to the sympathetic nervous system responses observed during fatiguing static forearm exercise where metabolite-sensitive afferents are the key determinants of sympathetic activation. In this report we examined whether forearm exercise training would attenuate sympathetic nervous system responses to rhythmic forearm exercise. We measured heart rate, mean arterial blood pressure (MAP), muscle sympathetic nerve activity (microneurography), plasma norepinephrine (NE), and NE spillover and clearance (tritiated NE kinetics) during nonfatiguing rhythmic forearm exercise before and after a 4-wk unilateral forearm training paradigm. Training had no effect on forearm mass, maximal voluntary contraction, or heart rate but did attenuate the increase in MAP (increase in MAP: from 15.2 +/- 1.8 before training to 11.4 +/- 1.4 mmHg after training; P < 0.017), muscle sympathetic nerve activity (increase in bursts: from 10.8 +/- 1.4 before training to 6.2 +/- 1.1 bursts/min after training; P < 0.030), and the NE spillover (increases in arterial spillover: from 1.3 +/- 0.2 before training to 0.6 +/- 0.2 nmol.min-1.m-2 after training, P < 0.014; increase in venous spillover: from 2.0 +/- 0.6 before training to 1.0 +/- 0.5 nmol.min-1.m-2 after training, P < 0.037) seen in response to exercise performed by the trained forearm. Thus forearm training reduces sympathetic responses during a nonfatiguing rhythmic handgrip paradigm that does not engage muscle metaboreceptors. We speculate that this effect is due to a conditioning-induced reduction in mechanically sensitive muscle afferent discharge.
Van Proeyen, Karen; Szlufcik, Karolina; Nielens, Henri; Ramaekers, Monique; Hespel, Peter
Training with limited carbohydrate availability can stimulate adaptations in muscle cells to facilitate energy production via fat oxidation. Here we investigated the effect of consistent training in the fasted state, vs. training in the fed state, on muscle metabolism and substrate selection during fasted exercise. Twenty young male volunteers participated in a 6-wk endurance training program (1-1.5 h cycling at ∼70% Vo(₂max), 4 days/wk) while receiving isocaloric carbohydrate-rich diets. Half of the subjects trained in the fasted state (F; n = 10), while the others ingested ample carbohydrates before (∼160 g) and during (1 g·kg body wt⁻¹·h⁻¹) the training sessions (CHO; n = 10). The training similarly increased Vo(₂max) (+9%) and performance in a 60-min simulated time trial (+8%) in both groups (P < 0.01). Metabolic measurements were made during a 2-h constant-load exercise bout in the fasted state at ∼65% pretraining Vo(₂max). In F, exercise-induced intramyocellular lipid (IMCL) breakdown was enhanced in type I fibers (P < 0.05) and tended to be increased in type IIa fibers (P = 0.07). Training did not affect IMCL breakdown in CHO. In addition, F (+21%) increased the exercise intensity corresponding to the maximal rate of fat oxidation more than did CHO (+6%) (P < 0.05). Furthermore, maximal citrate synthase (+47%) and β-hydroxyacyl coenzyme A dehydrogenase (+34%) activity was significantly upregulated in F (P < 0.05) but not in CHO. Also, only F prevented the development exercise-induced drop in blood glucose concentration (P < 0.05). In conclusion, F is more effective than CHO to increase muscular oxidative capacity and at the same time enhances exercise-induced net IMCL degradation. In addition, F but not CHO prevented drop of blood glucose concentration during fasting exercise.
Van Proeyen, Karen; Szlufcik, Karolina; Nielens, Henri; Ramaekers, Monique
Training with limited carbohydrate availability can stimulate adaptations in muscle cells to facilitate energy production via fat oxidation. Here we investigated the effect of consistent training in the fasted state, vs. training in the fed state, on muscle metabolism and substrate selection during fasted exercise. Twenty young male volunteers participated in a 6-wk endurance training program (1–1.5 h cycling at ∼70% V̇o2max, 4 days/wk) while receiving isocaloric carbohydrate-rich diets. Half of the subjects trained in the fasted state (F; n = 10), while the others ingested ample carbohydrates before (∼160 g) and during (1 g·kg body wt−1·h−1) the training sessions (CHO; n = 10). The training similarly increased V̇o2max (+9%) and performance in a 60-min simulated time trial (+8%) in both groups (P < 0.01). Metabolic measurements were made during a 2-h constant-load exercise bout in the fasted state at ∼65% pretraining V̇o2max. In F, exercise-induced intramyocellular lipid (IMCL) breakdown was enhanced in type I fibers (P < 0.05) and tended to be increased in type IIa fibers (P = 0.07). Training did not affect IMCL breakdown in CHO. In addition, F (+21%) increased the exercise intensity corresponding to the maximal rate of fat oxidation more than did CHO (+6%) (P < 0.05). Furthermore, maximal citrate synthase (+47%) and β-hydroxyacyl coenzyme A dehydrogenase (+34%) activity was significantly upregulated in F (P < 0.05) but not in CHO. Also, only F prevented the development exercise-induced drop in blood glucose concentration (P < 0.05). In conclusion, F is more effective than CHO to increase muscular oxidative capacity and at the same time enhances exercise-induced net IMCL degradation. In addition, F but not CHO prevented drop of blood glucose concentration during fasting exercise. PMID:21051570
Hargens, Alan R; Bhattacharya, Roshmi; Schneider, Suzanne M
When applied individually, exercise countermeasures employed to date do not fully protect the cardiovascular and musculoskeletal systems during prolonged spaceflight. Recent ground-based research suggests that it is necessary to perform exercise countermeasures within some form of artificial gravity to prevent microgravity deconditioning. In this regard, it is important to provide normal foot-ward loading and intravascular hydrostatic-pressure gradients to maintain musculoskeletal and cardiovascular function. Aerobic exercise within a centrifuge restores cardiovascular function, while aerobic exercise within lower body negative pressure restores cardiovascular function and helps protect the musculoskeletal system. Resistive exercise with vibration stimulation may increase the effectiveness of resistive exercise by preserving muscle function, allowing lower intensity exercises, and possibly reducing risk of loss of vision during prolonged spaceflight. Inexpensive methods to induce artificial gravity alone (to counteract head-ward fluid shifts) and exercise during artificial gravity (for example, by short-arm centrifuge or exercise within lower body negative pressure) should be developed further and evaluated as multi-system countermeasures.
Denham, Joshua; Nelson, Christopher P; O'Brien, Brendan J; Nankervis, Scott A; Denniff, Matthew; Harvey, Jack T; Marques, Francine Z; Codd, Veryan; Zukowska-Szczechowska, Ewa; Samani, Nilesh J; Tomaszewski, Maciej; Charchar, Fadi J
Telomere length is recognized as a marker of biological age, and shorter mean leukocyte telomere length is associated with increased risk of cardiovascular disease. It is unclear whether repeated exposure to ultra-endurance aerobic exercise is beneficial or detrimental in the long-term and whether it attenuates biological aging. We quantified 67 ultra-marathon runners' and 56 apparently healthy males' leukocyte telomere length (T/S ratio) using real-time quantitative PCR. The ultra-marathon runners had 11% longer telomeres (T/S ratio) than controls (ultra-marathon runners: T/S ratio = 3.5±0.68, controls: T/S ratio = 3.1±0.41; β = 0.40, SE = 0.10, P = 1.4×10(-4)) in age-adjusted analysis. The difference remained statistically significant after adjustment for cardiovascular risk factors (P = 2.2×10(-4)). The magnitude of this association translates into 16.2±0.26 years difference in biological age and approximately 324-648bp difference in leukocyte telomere length between ultra-marathon runners and healthy controls. Neither traditional cardiovascular risk factors nor markers of inflammation/adhesion molecules explained the difference in leukocyte telomere length between ultra-marathon runners and controls. Taken together these data suggest that regular engagement in ultra-endurance aerobic exercise attenuates cellular aging.
Wernbom, Mathias; Augustsson, Jesper; Thomeé, Roland
Strength training with low load under conditions of vascular occlusion has been proposed as an alternative to heavy-resistance exercise in the rehabilitation setting, when large forces acting upon the musculoskeletal system are unwanted. Little is known, however, about the relative intensity at which occlusion of blood flow significantly reduces dynamic muscular endurance and, hence, when it may increase the training effect. The purpose of this study was to investigate endurance during dynamic knee extension at different loads with and without cuff occlusion. Sixteen subjects (20-45 years of age) with strength-training experience were recruited. At 4 test sessions, the subjects performed unilateral knee extensions to failure with and without a pressure cuff around the thigh at 20, 30, 40, and 50% of their 1 repetition maximum (1RM). The pressure cuff was inflated to 200 mm Hg during exercise with occlusion. Significant differences in the number of repetitions performed were found between occluded and nonoccluded conditions for loads of 20, 30, and 40% of 1RM (p < 0.01) but not for the 50% load (p = 0.465). Thus, the application of a pressure cuff around the thigh appears to reduce dynamic knee extension endurance more at a low load than at a moderate load. These results may have implications regarding when it could be useful to apply a tourniquet in order to increase the rate of fatigue and perhaps also the resulting training effect. However, the short- and long-term safety of training under ischemic conditions needs to be addressed in both healthy and less healthy populations. Furthermore, the high acute pain ratings and the delayed-onset muscle soreness associated with this type of training may limit its potential use to highly motivated individuals.
Schumacher, Yorck O; Garvican, Laura A; Christian, Ryan; Lobigs, Louisa M; Qi, Jiliang; Fan, Rongyun; He, Yingying; Wang, Hailing; Gore, Christopher J; Ma, Fuhai
The Athlete Biological Passport (ABP) detects blood doping in athletes through longitudinal monitoring of erythropoietic markers. Mathematical algorithms are used to define individual reference ranges for these markers for each athlete. It is unclear if altitude and exercise can affect the variables included in these calculations in a way that the changes might be mistaken for blood manipulation. The aim of this study was to investigate the influence of the simultaneous strenuous exercise and low to high altitude exposure on the calculation algorithms of the ABP. 14 sea level (SL) and 11 altitude native (ALT) highly trained athletes participated in a 14-day cycling stage race taking place at an average altitude of 2496 m above sea level (min. 1014 m, max. 4120 m), race distances ranged between 96 and 227 km per day. ABP blood measures were taken on days -1,3,6,10,14 (SL) and -1,9,15 (ALT) of the race. Four results from three samples of two different SL athletes exceeded the individual limits at the 99% specificity threshold and one value at 99.9%. In ALT, three results from three samples of three different athletes were beyond the individual limits at 99%, one at 99.9%. The variations could be explained by the expected physiological reaction to exercise and altitude. In summary, the abnormalities observed in the haematological ABP´s of well-trained athletes during extensive exercise at altitude are limited and in line with expected physiological changes.
Xu, Chao; Lv, Junli; Lo, Y Martin; Cui, Steve W; Hu, Xinzhong; Fan, Mingtao
Oat β-glucan was purified from oat bran and its effects on running performance and related biochemical parameters were investigated. Four-week-old male Sparsgue-Dawley rats, fed with/without oat β-glucan (312.5 mg kg(-1) d(-1)) for 7 weeks, were subjected to run on a treadmill system to make them exhausted. All rats were immediately sacrificed after prolonged exercise, and the major metabolic substrates were measured in serum and liver. The results showed feeding dietary oat β-glucan to rats could significantly reduce the body weight and increase the maximum running time compared with normal control (P<0.05). Furthermore, dietary oat β-glucan decreased the levels of blood urea nitrogen, lactate acid, and creatine kinase activity in serum, and increased the levels of non-esterified fatty acids, lactic dehydrogenase activity in serum, and the content of liver glycogen. Therefore, the present study demonstrated that dietary oat β-glucan can enhance the endurance capacity of rats while facilitating their recovery from fatigue.
Zheng, Xinyan; Takatsu, Satomi; Wang, Hongli; Hasegawa, Hiroshi
The purpose of this study was to examine changes of thermoregulation, neurotransmitters in the preoptic area and anterior hypothalamus (PO/AH), which is the thermoregulatory center, and endurance exercise performance after the intraperitoneal injection of caffeine in rats. Core body temperature (Tcore), oxygen consumption (VO₂) and tail skin temperature (Ttail) were measured. A microdialysis probe was inserted in the PO/AH, and samples for the measurements of extracellular dopamine (DA), noradrenaline (NA) and serotonin (5-HT) levels were collected. During the rest experiment, 1 h after baseline collections in the chamber (23 °C), the rats were intraperitoneally injected with saline, or 3 mg kg(-1) or 10 mg kg(-1) caffeine. The duration of the test was 4 h. During the exercise experiment, baseline collections on the treadmill were obtained for 1 h. One hour before the start of exercise, rats were intraperitoneally injected with either 10 mg kg(-1) caffeine (CAF) or saline (SAL). Animals ran until fatigue at a speed of 18 m min(-1), at a 5% grade, on the treadmill in a normal environment (23 °C). At rest, 3 mg kg(-1) caffeine did not influence Tcore, Ttail, VO₂, extracellular DA, NA and 5-HT. 10 mg kg(-1) caffeine caused significant increases in Tcore, VO₂, Ttail and extracellular DA in the PO/AH. In addition, 10 mg kg(-1) caffeine increased the run time to fatigue (SAL: 104.4 ± 30.9 min, CAF: 134.0 ± 31.1 min, p<0.05). The combination of caffeine and exercise increased Tcore, VO₂, Ttail and extracellular DA in the PO/AH. NA increased during exercise, while neither caffeine nor exercise changed 5-HT. These results indicate that caffeine has ergogenic and hyperthermic effects, and these effects may be related to changes of DA release in the brain.
Tonkonogi, Michail; Harris, Beorn; Sahlin, Kent
The influence of prolonged exhaustive exercise on mitochondrial oxidative function was investigated in ten men. Muscle biopsies were taken before and after exercise and mitochondrial respiration investigated in fibre bundles made permeable by pretreatment with saponin. After exercise, respiration in the absence of ADP increased by 18 % (P < 0.01), but respiration at suboptimal ADP concentration (0.1 mM) and maximal ADP-stimulated respiration (1 mM ADP) remained unchanged. In the presence of creatine (20 mM), mitochondrial affinity for ADP increased markedly and respiration at suboptimal ADP concentration (0.1 mM) was similar (pre-exercise) or higher (post-exercise; P < 0.05) than with 1 mM ADP alone. The increase in respiratory rate with creatine was correlated to the relative type I fibre area (r = 0.84). Creatine-stimulated respiration increased after prolonged exercise (P < 0.01). The respiratory control index (6.8 ± 0.4, mean ± s.e.m.) and the ratio between respiration at 0.1 and 1 mM ADP (ADP sensitivity index, 0.63 ± 0.03) were not changed after exercise. The sensitivity index was negatively correlated to the relative type I fibre area (r = −0.86). The influence of exercise on muscle oxidative function has for the first time been investigated with the skinned-fibre technique. It is concluded that maximal mitochondrial oxidative power is intact or improved after prolonged exercise, while uncoupled respiration is increased. The latter finding may contribute to the elevated post-exercise oxygen consumption. The finding that the sensitivity of mitochondrial respiration for ADP and creatine are related to fibre-type composition indicates intrinsic differences in the control of mitochondrial respiration between fibres. PMID:9625884
Shockett, Penny E; Khanal, Januka; Sitaula, Alina; Oglesby, Christopher; Meachum, William A; Castracane, V Daniel; Kraemer, Robert R
Increased plasma cell-free mitochondrial DNA (cf-mDNA), a damage-associated molecular pattern (DAMP) produced by cellular injury, contributes to neutrophil activation/inflammation in trauma patients and arises in cancer and autoimmunity. To further understand relationships between cf-mDNA released by tissue injury, inflammation, and health benefits of exercise, we examined cf-mDNA response to prolonged moderate aerobic exercise. Seven healthy moderately trained young men (age = 22.4 ± 1.2) completed a treadmill exercise trial for 90 min at 60% VO2 max and a resting control trial. Blood was sampled immediately prior to exercise (0 min = baseline), during (+18, +54 min), immediately after (+90 min), and after recovery (R40). Plasma was analyzed for cf-mDNA, IL-6, and lactate. A significant difference in cf-mDNA response was observed between exercise and control trials, with cf-mDNA levels reduced during exercise at +54 and +90 (with or without plasma volume shift correction). Declines in cf-mDNA were accompanied by increased lactate and followed by an increase in IL-6, suggesting a temporal association with muscle stress and inflammatory processes. Our novel finding of cf-mDNA decline with prolonged moderate treadmill exercise provides evidence for increased clearance from or reduced release of cf-mDNA into the blood with prolonged exercise. These studies contrast with previous investigations involving exhaustive short-term treadmill exercise, in which no change in cf-mDNA levels were reported, and contribute to our understanding of differences between exercise- and trauma-induced inflammation. We propose that transient declines in cf-mDNA may induce health benefits, by reducing systemic inflammation.
Thomas, D E; Brotherhood, J R; Miller, J B
It was hypothesized that slowly digested carbohydrates, that is, low glycemic index (GI) foods, eaten before prolonged strenuous exercise would increase the blood glucose concentration toward the end of exercise. Six trained cyclists pedaled on a cycle ergometer at 65-70% VO2max 60 min after ingestion of each of four test meals: a low-GI and a high-GI powdered food and a low-GI and a high-GI breakfast cereal, all providing 1 g of available carbohydrate per kilogram of body mass. Plasma glucose levels after more that 90 min of exercise were found to correlate inversely with the observed GI of the foods (p < .01). Free fatty acid levels during the last hour of exercise also correlated inversely with the GI (p < .05). The findings suggest that the slow digestion of carbohydrate in the prevent food favors higher concentrations of fuels in the blood toward the end of exercise.
Backhouse, S H; Ali, A; Biddle, S J H; Williams, C
This study was designed to determine the effects of ingesting a carbohydrate (CHO) solution on affective states and rating of perceived exertion (RPE) during prolonged intermittent high-intensity exercise. Seventeen male soccer players completed a prolonged intermittent high-intensity exercise protocol for 90 min on two occasions, separated by at least 7 days. Participants consumed either a 6.4% CHO (0.6 g/kg body mass (BM)/h) or an artificially sweetened placebo (PLA) solution immediately before (8 mL/kg BM) and every 15 min (3 mL/kg BM) during exercise in a double-blind, counterbalanced design. Pleasure-displeasure, perceived activation, RPE and plasma glucose concentration was assessed. The results showed that compared with the CHO trial, perceived activation were lower in the placebo trial during the last 30 min of exercise and this was accompanied by lowered plasma glucose concentrations. In the CHO trial, RPE was maintained in the last 30 min of exercise but carried on increasing in the PLA trial. Therefore, CHO ingestion during prolonged high-intensity exercise appears to elicit an enhanced perceived activation profile that may impact upon task persistence and performance. This finding is in addition to the physiological and metabolic benefits of the exogenous energy supply.
Marcell, Taylor J; Hawkins, Steven A; Wiswell, Robert A
Age-associated loss of muscle mass (sarcopenia) and strength (dynapenia) is associated with a loss of independence that contributes to falls, fractures, and nursing home admissions, whereas regular physical activity has been suggested to offset these losses. The purpose of this study was to evaluate the effect of habitual endurance exercise on muscle mass and strength in active older adults. A longitudinal analysis of muscle strength (≈4.8 years apart) was performed on 59 men (age at start of study: 58.6 ± 7.3 years) and 35 women (56.9 ± 8.2 years) who used endurance running as their primary mode of exercise. There were no changes in fat-free mass although body fat increased minimally (1.0-1.5%). Training volume (km·wk, d·wk) decreased in both the men and women. There was a significant loss of both isometric knee extension (≈5% per year) and knee flexion (≈3.6% per year) strength in both the men and women. However, there was no significant change in either isokinetic concentric or eccentric torque of the knee extensors. Our data demonstrated a significant decline in isometric knee extensor and knee flexor strength although there were no changes in body mass in this group of very active older men and women. Our data support newer exercise guidelines for older Americans suggesting resistance training be an integral component of a fitness program and that running alone was not sufficient to prevent the loss in muscle strength (dynapenia) with aging.
Hostrup, Morten; Kalsen, Anders; Auchenberg, Michael; Rzeppa, Sebastian; Hemmersbach, Peter; Bangsbo, Jens; Backer, Vibeke
Our objective was to investigate urine concentrations of 8 mg oral salbutamol in samples collected after intense exercise in endurance athletes. Nine male endurance athletes with a VO2max of 70.2 ± 5.9 mL/min/kg (mean ± SD) took part in the study. Two hours after administration of 8 mg oral salbutamol, subjects performed submaximal exercise for 15 min followed by two, 2-min exercise bouts at an intensity corresponding to 110% of VO2max and a bout to exhaustion at same intensity. Urine samples were collected 4, 8, and 12 h following administration of salbutamol. Samples were analyzed by the Norwegian World Anti-doping Agency (WADA) laboratory. Adjustment of urine concentrations of salbutamol to a urine specific gravity (USG) of 1.020 g/mL was compared with no adjustment according to WADA's technical documents. We observed greater (P = 0.01) urine concentrations of salbutamol 4 h after administration when samples were adjusted to a USG of 1.020 g/mL compared with no adjustment (3089 ± 911 vs. 1918 ± 1081 ng/mL). With the current urine decision limit of 1200 ng/mL for salbutamol on WADA's 2013 list of prohibited substances, fewer false negative urine samples were observed when adjusted to a USG of 1.020 g/mL compared with no adjustment. In conclusion, adjustment of urine samples to a USG of 1.020 g/mL decreases risk of false negative doping tests after administration of oral salbutamol. Adjusting urine samples for USG might be useful when evaluating urine concentrations of salbutamol in doping cases.
Fleming, Jesse; Sharman, Matthew J; Avery, Neva G; Love, Dawn M; Gómez, Ana L; Scheett, Timothy P; Kraemer, William J; Volek, Jeff S
The effects of adaptation to a high-fat diet on endurance performance are equivocal, and there is little data regarding the effects on high-intensity exercise performance. This study examined the effects of a high-fat/moderate protein diet on submaximal, maximal, and supramaximal performance. Twenty non-highly trained men were assigned to either a high-fat/moderate protein (HFMP; 61% fat diet) (n = 12) or a control (C; 25% fat) group (n = 8). A maximal oxygen consumption test, two 30-s Wingate anaerobic tests, and a 45-min timed ride were performed before and after 6 weeks of diet and training. Body mass decreased significantly (-2.2 kg; p < or = .05) in HFMP subjects. Maximal oxygen consumption significantly decreased in the HFMP group (3.5 +/- 0.14 to 3.27 +/- 0.09 L x min(-1)) but was unaffected when corrected for body mass. Perceived exertion was significantly higher during this test in the HFMP group. Main time effects indicated that peak and mean power decreased significantly during bout 1 of the Wingate sprints in the HFMP (-10 and -20%, respectively) group but not the C (-8 and -16%, respectively) group. Only peak power was lower during bout 1 in the HFMP group when corrected for body mass. Despite significantly reduced RER values in the HFMP group during the 45-min cycling bout, work output was significantly decreased (-18%). Adaptation to a 6-week HFMP diet in non-highly trained men resulted in increased fat oxidation during exercise and small decrements in peak power output and endurance performance. These deleterious effects on exercise performance may be accounted for in part by a reduction in body mass and/or increased ratings of perceived exertion.
Calbet, J A L; De Paz, J A; Garatachea, N; Cabeza de Vaca, S; Chavarren, J
The aim of this study was to evaluate the effects of severe acute hypoxia on exercise performance and metabolism during 30-s Wingate tests. Five endurance- (E) and five sprint- (S) trained track cyclists from the Spanish National Team performed 30-s Wingate tests in normoxia and hypoxia (inspired O(2) fraction = 0.10). Oxygen deficit was estimated from submaximal cycling economy tests by use of a nonlinear model. E cyclists showed higher maximal O(2) uptake than S (72 +/- 1 and 62 +/- 2 ml x kg(-1) x min(-1), P < 0.05). S cyclists achieved higher peak and mean power output, and 33% larger oxygen deficit than E (P < 0.05). During the Wingate test in normoxia, S relied more on anaerobic energy sources than E (P < 0.05); however, S showed a larger fatigue index in both conditions (P < 0.05). Compared with normoxia, hypoxia lowered O(2) uptake by 16% in E and S (P < 0.05). Peak power output, fatigue index, and exercise femoral vein blood lactate concentration were not altered by hypoxia in any group. Endurance cyclists, unlike S, maintained their mean power output in hypoxia by increasing their anaerobic energy production, as shown by 7% greater oxygen deficit and 11% higher postexercise lactate concentration. In conclusion, performance during 30-s Wingate tests in severe acute hypoxia is maintained or barely reduced owing to the enhancement of the anaerobic energy release. The effect of severe acute hypoxia on supramaximal exercise performance depends on training background.
Luck, Margaux M; Le Moyec, Laurence; Barrey, Eric; Triba, Mohamed N; Bouchemal, Nadia; Savarin, Philippe; Robert, Céline
Long-term endurance exercise severely affects metabolism in both human and animal athletes resulting in serious risk of metabolic disorders during or after competition. Young horses (up to 6 years old) can compete in races up to 90 km despite limited scientific knowledge of energetic metabolism responses to long distance exercise in these animals. The hypothesis of this study was that there would be a strong effect of endurance exercise on the metabolomic profiles of young horses and that the energetic metabolism response in young horses would be different from that of more experienced horses. Metabolomic profiling is a powerful method that combines Nuclear Magnetic Resonance (NMR) spectrometry with supervised Orthogonal Projection on Latent Structure (OPLS) statistical analysis. (1)H-NMR spectra were obtained from plasma samples drawn from young horses (before and after competition). The spectra obtained before and after the race from the same horse (92 samples) were compared using OPLS. The statistical parameters showed the robustness of the model (R2Y = 0.947, Q2Y = 0.856 and cros-validated ANOVA p < 0.001). For confirmation of the predictive value of the model, a test set of 104 sample spectra were projected by the model, which provided perfect predictions as the area under the receiving-operator curve was 1. The metabolomic profile determined with the OPLS model showed that glycemia after the race was lower than glycemia before the race, despite the involvement of lipid and protein catabolism. An OPLS model was calculated to compare spectra obtained on plasma taken after the race from 6-year-old horses and from experienced horses (cross-validated ANOVA p < 0.001). The comparison of metabolomic profiles in young horses to those from experienced horses showed that experienced horses maintained their glycemia with higher levels of lactate and a decrease of plasma lipids after the race.
Background The aetiology and clinical significance of troponin release following endurance exercise is unclear but may be due to transient myocardial inflammation. Cardiovascular magnetic resonance (CMR) affords us the opportunity to evaluate the presence of myocardial inflammation and focal fibrosis and is the ideal imaging modality to study this hypothesis. We sought to correlate the relationship between acute bouts of ultra endurance exercise leading to cardiac biomarkers elevation and the presence of myocardial inflammation and fibrosis using CMR. Methods 17 recreation athletes (33.5 +/- 6.5 years) were studied before and after a marathon run with troponin, NTproBNP, and CMR. Specific imaging parameters to look for inflammation included T2 weighted images, and T1 weighted spin-echo images before and after an intravenous gadolinium-DTPA to detect myocardial hyperemia secondary to inflammation. Late gadolinium imaging was performed (LGE) to detect any focal regions of replacement fibrosis. Results Eleven of the 17 participant had elevations of TnI above levels of cut off for myocardial infarction 6 hrs after the marathon (0.075 +/- 0.02, p = 0.007). Left ventricular volumes were reduced post marathon and a small increase in ejection fraction was noted (64+/- 1% pre, 67+/- 1.2% post, P = 0.014). Right ventricular volumes, stroke volume, and ejection fraction were unchanged post marathon. No athlete fulfilled criteria for myocardial inflammation based on current criteria. No regions of focal fibrosis were seen in any of the participants. Conclusion Exercise induced cardiac biomarker release is not associated with any functional changes by CMR or any detectable myocardial inflammation or fibrosis. PMID:20598139
Luck, Margaux M.; Le Moyec, Laurence; Barrey, Eric; Triba, Mohamed N.; Bouchemal, Nadia; Savarin, Philippe; Robert, Céline
Long-term endurance exercise severely affects metabolism in both human and animal athletes resulting in serious risk of metabolic disorders during or after competition. Young horses (up to 6 years old) can compete in races up to 90 km despite limited scientific knowledge of energetic metabolism responses to long distance exercise in these animals. The hypothesis of this study was that there would be a strong effect of endurance exercise on the metabolomic profiles of young horses and that the energetic metabolism response in young horses would be different from that of more experienced horses. Metabolomic profiling is a powerful method that combines Nuclear Magnetic Resonance (NMR) spectrometry with supervised Orthogonal Projection on Latent Structure (OPLS) statistical analysis. 1H-NMR spectra were obtained from plasma samples drawn from young horses (before and after competition). The spectra obtained before and after the race from the same horse (92 samples) were compared using OPLS. The statistical parameters showed the robustness of the model (R2Y = 0.947, Q2Y = 0.856 and cros-validated ANOVA p < 0.001). For confirmation of the predictive value of the model, a test set of 104 sample spectra were projected by the model, which provided perfect predictions as the area under the receiving-operator curve was 1. The metabolomic profile determined with the OPLS model showed that glycemia after the race was lower than glycemia before the race, despite the involvement of lipid and protein catabolism. An OPLS model was calculated to compare spectra obtained on plasma taken after the race from 6-year-old horses and from experienced horses (cross-validated ANOVA p < 0.001). The comparison of metabolomic profiles in young horses to those from experienced horses showed that experienced horses maintained their glycemia with higher levels of lactate and a decrease of plasma lipids after the race. PMID:26347654
Lepers, Romuald; Marcora, Samuele M.
We recently developed a high intensity one leg dynamic exercise (OLDE) protocol to measure muscle endurance and investigate the central and peripheral mechanisms of muscle fatigue. The aims of the present study were to establish the reliability of this novel protocol and describe the isokinetic muscle fatigue induced by high intensity OLDE and its recovery. Eight subjects performed the OLDE protocol (time to exhaustion test of the right leg at 85% of peak power output) three times over a week period. Isokinetic maximal voluntary contraction torque at 60 (MVC60), 100 (MVC100) and 140 (MVC140) deg/s was measured pre-exercise, shortly after exhaustion (13 ± 4 s), 20 s (P20) and 40 s (P40) post-exercise. Electromyographic (EMG) signal was analyzed via the root mean square (RMS) for all three superficial knee extensors. Mean time to exhaustion was 5.96 ± 1.40 min, coefficient of variation was 8.42 ± 6.24%, typical error of measurement was 0.30 min and intraclass correlation was 0.795. MVC torque decreased shortly after exhaustion for all angular velocities (all P < 0.001). MVC60 and MVC100 recovered between P20 (P < 0.05) and exhaustion and then plateaued. MVC140 recovered only at P40 (P < 0.05). High intensity OLDE did not alter maximal EMG RMS of the three superficial knee extensors during MVC. The results of this study demonstrate that this novel high intensity OLDE protocol could be reliably used to measure muscle endurance, and that muscle fatigue induced by high intensity OLDE should be examined within ~ 30 s following exhaustion. PMID:27706196
Objectives The aim of this study was to evaluate the effects of caffeine on physiological responses to submaximal exercise, with a focus on blood lactate concentration ([BLa]). Methods Using a randomised, single-blind, crossover design; 16 endurance-trained, male cyclists (age: 38 ± 8 years; height: 1.80 ± 0.05 m; body mass: 76.6 ± 7.8 kg; V˙O2max: 4.3 ± 0.6 L∙min-1) completed four trials on an electromagnetically-braked cycle ergometer. Each trial consisted of a six-stage incremental test (3 minute stages) followed by 30 minutes of passive recovery. One hour before trials 2–4, participants ingested a capsule containing 5 mg∙kg-1 of either caffeine or placebo (maltodextrin). Trials 2 and 3 were designed to evaluate the effects of caffeine on various physiological responses during exercise and recovery. In contrast, Trial 4 was designed to evaluate the effects of caffeine on [BLa] during passive recovery from an end-exercise concentration of 4 mmol∙L-1. Results Relative to placebo, caffeine increased [BLa] during exercise, independent of exercise intensity (mean difference: 0.33 ± 0.41 mmol∙L-1; 95% likely range: 0.11 to 0.55 mmol∙L-1), but did not affect the time-course of [BLa] during recovery (p = 0.604). Caffeine reduced ratings of perceived exertion (mean difference: 0.5 ± 0.7; 95% likely range: 0.1 to 0.9) and heart rate (mean difference: 3.6 ± 4.2 b∙min-1; 95% likely range: 1.3 to 5.8 b∙min-1) during exercise, with the effect on the latter dissipating as exercise intensity increased. Supplement × exercise intensity interactions were observed for respiratory exchange ratio (p = 0.004) and minute ventilation (p = 0.034). Conclusions The results of the present study illustrate the clear, though often subtle, effects of caffeine on physiological responses to submaximal exercise. Researchers should be aware of these responses, particularly when evaluating the physiological effects of various experimental interventions. PMID:27532605
Hodgson, Adrian B; Randell, Rebecca K; Jeukendrup, Asker E
There is consistent evidence supporting the ergogenic effects of caffeine for endurance based exercise. However, whether caffeine ingested through coffee has the same effects is still subject to debate. The primary aim of the study was to investigate the performance enhancing effects of caffeine and coffee using a time trial performance test, while also investigating the metabolic effects of caffeine and coffee. In a single-blind, crossover, randomised counter-balanced study design, eight trained male cyclists/triathletes (Mean ± SD: Age 41 ± 7 y, Height 1.80 ± 0.04 m, Weight 78.9 ± 4.1 kg, VO2 max 58 ± 3 ml • kg(-1) • min(-1)) completed 30 min of steady-state (SS) cycling at approximately 55% VO2max followed by a 45 min energy based target time trial (TT). One hour prior to exercise each athlete consumed drinks consisting of caffeine (5 mg CAF/kg BW), instant coffee (5 mg CAF/kg BW), instant decaffeinated coffee or placebo. The set workloads produced similar relative exercise intensities during the SS for all drinks, with no observed difference in carbohydrate or fat oxidation. Performance times during the TT were significantly faster (~5.0%) for both caffeine and coffee when compared to placebo and decaf (38.35 ± 1.53, 38.27 ± 1.80, 40.23 ± 1.98, 40.31 ± 1.22 min respectively, p<0.05). The significantly faster performance times were similar for both caffeine and coffee. Average power for caffeine and coffee during the TT was significantly greater when compared to placebo and decaf (294 ± 21 W, 291 ± 22 W, 277 ± 14 W, 276 ± 23 W respectively, p<0.05). No significant differences were observed between placebo and decaf during the TT. The present study illustrates that both caffeine (5 mg/kg/BW) and coffee (5 mg/kg/BW) consumed 1 h prior to exercise can improve endurance exercise performance.
Background: Alterations in respiratory mechanics predispose healthy obese individuals to low lung volume breathing, which places them at risk of developing expiratory flow limitation (EFL). The high ventilatory demand in endurance-trained obese adults further increases their risk of developing EFL and increases their work of breathing. The objective of this study was to investigate the prevalence and magnitude of EFL in fit obese (FO) adults via measurements of breathing mechanics and ventilatory dynamics during exercise. Methods: Ten (seven women and three men) FO (mean ± SD, 38 ± 5 years, 38% ± 5% body fat) and 10 (seven women and three men) control obese (CO) (38 ± 5 years, 39% ± 5% body fat) subjects underwent hydrostatic weighing, pulmonary function testing, cycle exercise testing, and the determination of the oxygen cost of breathing during eucapnic voluntary hyperpnea. Results: There were no differences in functional residual capacity (43% ± 6% vs 40% ± 9% total lung capacity [TLC]), residual volume (21% ± 4% vs 21% ± 4% TLC), or FVC (111% ± 13% vs 104% ± 15% predicted) between FO and CO subjects, respectively. FO subjects had higher FEV1 (111% ± 13% vs 99% ± 11% predicted), TLC (106% ± 14% vs 94% ± 7% predicted), peak expiratory flow (123% ± 14% vs 106% ± 13% predicted), and maximal voluntary ventilation (128% ± 15% vs 106% ± 13% predicted) than did CO subjects. Peak oxygen uptake (129% ± 16% vs 86% ± 15% predicted), minute ventilation (128 ± 35 L/min vs 92 ± 25 L/min), and work rate (229 ± 54 W vs 166 ± 55 W) were higher in FO subjects. Mean inspiratory (4.65 ± 1.09 L/s vs 3.06 ± 1.21 L/s) and expiratory (4.15 ± 0.95 L/s vs 2.98 ± 0.76L/s) flows were greater in FO subjects, which yielded a greater breathing frequency (51 ± 8 breaths/min vs 41 ± 10 breaths/min) at peak exercise in FO subjects. Mechanical ventilatory constraints in FO subjects were similar to those in CO subjects despite the greater ventilatory demand in FO
Pawelczyk, J A; Kenney, W L; Kenney, P
The cardiovascular responses to 10 min of orthostasis were assessed before and after an aerobic exercise program. Five men and five women (18-25 years old) exercised for 7 weeks, four times per week, for 50 min per session at 70% of maximal heart rate (HR). Before and after the exercise program, maximal aerobic power (VO2max) was determined, and HR, systolic (SBP), diastolic (DBP), and pulse (PP) blood pressures were measured each minute during 5 min of supine rest, 10 min of foot-supported 70 degree head-up tilt (HUT), and 5 min of supine rest. Orthostatic tolerance was not determined. Calf compliance was measured in five of the subjects before and after the program as the change in leg volume at occluding pressures of 20, 40, 60, 80, and 100 mm Hg. Following the program, VO2max increased by 8.7% (p = 0.012), while decreases were noted in resting HR (9.4%, p = 0.041), SBP (5.0%, p less than 0.0005), and DBP (14.2%, p less than 0.0005). Despite a greater HR increase during HUT (7.1 beat.min-1, p = 0.034), SBP decreased by 3.4 mm Hg during HUT after the exercise program (p = 0.008). No differences were noted in the changes in DBP, MAP, or PP upon tilting (p greater than 0.05). After the program, the amount of fluid pooled in the calf at high occluding pressures (80 and 100 mm Hg) increased by 0.96 +/- 0.24 and 1.10 +/- 0.33 ml.100 ml tissue-1 (X +/- S.E.M., p = 0.017 and p = 0.028, respectively). We suggest that control of blood pressure during 10 min of orthostasis may be altered by endurance exercise training.
Biondich, Amy Sue
Introduction. We describe a novel scale and its field use for evaluation of exercise-associated gastroparesis in the endurance athlete. Methods. A scale was created based on gastroparesis tools previously described in the medical literature. Surveys of the tool were administered to runners participating in a 210 km multiday foot race in Sri Lanka. Results. Use of this novel scale was demonstrated to be useful in assessing gastroparesis severity scores of athletes and how these symptoms affected their race performance. Of the 27 race participants who completed the survey, 27 felt that the tool adequately captured their symptoms. Conclusions. This novel survey tool was able to assess the presence and severity of exercise-associated gastroparesis symptoms in endurance racers in a remote location. This tool may be helpful with further research of the identification and management of gastroparesis and other gastrointestinal upset in the endurance race environment. PMID:27981229
Capomaccio, S; Cappelli, K; Barrey, E; Felicetti, M; Silvestrelli, M; Verini-Supplizi, A
It is known that moderate physical activity may have beneficial effects on health, whereas strenuous effort induces a state resembling inflammation. The molecular mechanisms underlying the cellular response to exercise remain unclear, although it is clear that the immune system plays a key role. It has been hypothesized that the physio-pathological condition that develops in athletes subjected to heavy training is caused by derangement of cellular immune regulation. The purpose of the present study was to obtain information on endurance horse gene transcription under strenuous conditions and to identify candidate genes causing immune system derangement. We performed a wide gene expression scan, using microarray technology, on peripheral blood mononuclear cells of ten horses chosen from high-level participants in national and international endurance races. The use of three different timepoints revealed changes in gene expression when post-effort samples (T1, taken immediately after the race; and T2, taken 24 h after the race) were compared with basal sample (T0, at rest). Statistical analysis showed no differences in gene expression between T0 and T2 samples, indicating complete restoration of homeostasis by 24 h after racing, whereas T1 showed strong modulation of expression, affecting 132 genes (97 upregulated, 35 downregulated). Ingenuity pathway analysis revealed that the main mechanisms and biofunctions involved were significantly associated with immunological and inflammatory responses. Real-time PCR was performed on 26 gene products to validate the array data.
Chenevière, Xavier; Borrani, Fabio; Droz, David; Gojanovic, Boris; Malatesta, Davide
This study aimed to compare the effects of 2 different prior endurance exercises on subsequent whole-body fat oxidation kinetics. Fifteen men performed 2 identical submaximal incremental tests (Incr2) on a cycle ergometer after (i) a ∼40-min submaximal incremental test (Incr1) followed by a 90-min continuous exercise performed at 50% of maximal aerobic power-output and a 1-h rest period (Heavy); and (ii) Incr1 followed by a 2.5-h rest period (Light). Fat oxidation was measured using indirect calorimetry and plotted as a function of exercise intensity during Incr1 and Incr2. A sinusoidal equation, including 3 independent variables (dilatation, symmetry and translation), was used to characterize the fat oxidation kinetics and to determine the intensity (Fat(max)) that elicited the maximal fat oxidation (MFO) during Incr. After the Heavy and Light trials, Fat(max), MFO, and fat oxidation rates were significantly greater during Incr2 than Incr1 (p < 0.001). However, Δ (i.e., Incr2-Incr1) Fat(max), MFO, and fat oxidation rates were greater in the Heavy compared with the Light trial (p < 0.05). The fat oxidation kinetics during Incr2(Heavy) showed a greater dilatation and rightward asymmetry than Incr1(Heavy), whereas only a greater dilatation was observed in Incr2(Light) (p < 0.05). This study showed that although to a lesser extent in the Light trial, both prior exercise sessions led to an increase in Fat(max), MFO, and absolute fat oxidation rates during Incr2, inducing significant changes in the shape of the fat oxidation kinetics.
Sancho-González, Ignacio; Bonilla-Hernández, María Vicenta; Ibañez-Muñoz, David; Vicente-Campos, Davinia; Chicharro, José López
Triathlon followers increase each year and long-distance events have seen major growth worldwide. In the cycling phase, athletes must maintain an aerodynamic posture on the bike for long periods of time. We report a case of a 38-year-old triathlete with symptoms of an axillary vein thrombosis 48h after a long triathlon competition. After 3days of hospitalization with a treatment consisted on enoxaparin anticoagulant and acenocumarol, the patient was discharged with instructions to continue treatment under home hospitalization with acetaminophen. Four weeks after the process, the patient was asymptomatic and the diameter of his arm was near normality. Due to the growing popularity of events based on endurance exercise, it is necessary more research to determine the etiopathogeny of deep venous thrombosis in athletes.
Kaikkonen, P; Rusko, H; Martinmäki, K
Methodological problems have limited the number of studies on heart rate variability (HRV) dynamics immediately after exercise. We used the short-time Fourier transform method to study immediate (5 min) and slow (30 min) recovery of HRV after different high-intensity exercise interventions. Eight male athletes performed two interval interventions at 85% and 93% (IV(85) and IV(93)) and two continuous interventions at 80% and 85% (CO(80) and CO(85)) of the velocity at VO2max (vVO2max). We found no increase in high frequency power (HFP), but low frequency (LFP) and total power (TP) increased (P<0.05) during the first 5 min of the recovery after each intervention. During the 30-min recovery, HFP, LFP and TP (1) increased slowly toward resting values, but HFP remained lower (P<0.01) than at rest, (2) were lower (P<0.05) after IV(93) and CO(85) when compared with IV(85) and CO(80), respectively and (3) were lower (P<0.01) after CO(85) when compared with IV(85). HRV recovery was detected during the immediate recovery after interventions. Increased exercise intensity resulted in lower HRV both in interval and in continuous interventions. In addition, when interval and continuous interventions were performed at a similar workload, HRV was lower after continuous intervention.
Tempest, Gavin D; Davranche, Karen; Brisswalter, Jeanick; Perrey, Stephane; Radel, Rémi
The acute-exercise effects upon cognitive functions are varied and dependent upon exercise duration and intensity, and the type of cognitive tasks assessed. The hypofrontality hypothesis assumes that prolonged exercise, at physiologically challenging intensities, is detrimental to executive functions due to cerebral perturbations (indicated by reduced prefrontal activity). The present study aimed to test this hypothesis by measuring oxygenation in prefrontal and motor regions using near-infrared spectroscopy during two executive tasks (flanker task and 2-back task) performed while cycling for 60min at a very low intensity and an intensity above the ventilatory threshold. Findings revealed that, compared to very low intensity, physiologically challenging exercise (i) shortened reaction time in the flanker task, (ii) impaired performance in the 2-back task, and (iii) initially increased oxygenation in prefrontal, but not motor regions, which then became stable in both regions over time. Therefore, during prolonged exercise, not only is the intensity of exercise assessed important, but also the nature of the cognitive processes involved in the task. In contrast to the hypofrontality hypothesis, no inverse pattern of oxygenation between prefrontal and motor regions was observed, and prefrontal oxygenation was maintained over time. The present results go against the hypofrontality hypothesis.
Waller, Amanda P; Heigenhauser, George J F; Geor, Raymond J; Spriet, Lawrence L; Lindinger, Michael I
We hypothesized that postexercise rehydration using a hypotonic electrolyte solution will increase the rate of recovery of whole body hydration, and that this is associated with increased muscle glycogen and electrolyte recovery in horses. Gluteus medius biopsies and jugular venous blood were sampled from six exercise-conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum, and either a hypotonic commercial electrolyte solution (electrolyte) via nasogastric tube, followed by a typical hay/grain meal, or a hay/grain meal alone (control). The CET resulted in decreased total body water and muscle glycogen concentration of 8.4 +/- 0.3 liters and 22.6%, respectively, in the control treatment, and 8.2 +/- 0.4 liters and 21.9% in the electrolyte treatment. Electrolyte resulted in an enhanced rate of muscle glycogen resynthesis and faster restoration of hydration (as evidenced by faster recovery of plasma protein concentration, maintenance of plasma osmolality, and greater muscle intracellular fluid volume) during the recovery period compared with control. There were no differences in muscle Na, K, Cl, or Mg contents between the two treatments. It is concluded that oral administration of a hypotonic electrolyte solution after prolonged moderate-intensity exercise enhanced the rate of muscle glycogen resynthesis during the recovery period compared with control. It is speculated that postexercise dehydration may be one key contributor to the slow muscle glycogen replenishment in horses.
Le Panse, Bénédicte; Thomasson, Rémi; Jollin, Laetitia; Lecoq, Anne-Marie; Amiot, Virgile; Rieth, Nathalie; De Ceaurriz, Jacques; Collomp, Katia
The present study investigated whether short-term oral administration of glucocorticoid would modify performance and selected hormonal and metabolic parameters during submaximal exercise in healthy women. Nine recreational female athletes completed cycling trials at 70-75% VO(2) max until exhaustion after either placebo (Pla, gelatin) or oral prednisone (Cor, Cortancyl, 50 mg per day for 1 week) treatment, according to a double-blind and randomized protocol. Blood samples were collected at rest; after 10, 20, and 30 min of exercise; at exhaustion; and after 10 and 20 min of passive recovery for adrenocorticotrophic hormone (ACTH), dehydroepiandrosterone (DHEA), prolactin (PRL), growth hormone (GH), insulin (Ins), blood glucose (Glu), and lactate (Lac) determination. Cycling time was significantly increased with short-term Cor intake (Cor: 66.4 +/- 8.4 vs. Pla: 47.9 +/- 6.7 min, P < 0.01). ACTH and DHEA remained completely blunted throughout the experiment with Cor versus Pla (P < 0.01), whereas GH and PRL were significantly decreased with Cor after, respectively, 20 and 30 min of exercise (P < 0.05). No significant difference in Ins or Glu values was found between the two treatments but Lac concentrations were significantly increased with Cor versus Pla between 10 and 30 min of exercise (P < 0.05). These data indicate that short-term glucocorticoid intake improved endurance performance in women, but further investigation is needed to determine whether these results are applicable to elite female athletes and, if so, current WADA legislation needs to be changed.
Lantier, Louise; Fentz, Joachim; Mounier, Rémi; Leclerc, Jocelyne; Treebak, Jonas T; Pehmøller, Christian; Sanz, Nieves; Sakakibara, Iori; Saint-Amand, Emmanuelle; Rimbaud, Stéphanie; Maire, Pascal; Marette, André; Ventura-Clapier, Renée; Ferry, Arnaud; Wojtaszewski, Jørgen F P; Foretz, Marc; Viollet, Benoit
AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that plays a central role in skeletal muscle metabolism. We used skeletal muscle-specific AMPKα1α2 double-knockout (mdKO) mice to provide direct genetic evidence of the physiological importance of AMPK in regulating muscle exercise capacity, mitochondrial function, and contraction-stimulated glucose uptake. Exercise performance was significantly reduced in the mdKO mice, with a reduction in maximal force production and fatigue resistance. An increase in the proportion of myofibers with centralized nuclei was noted, as well as an elevated expression of interleukin 6 (IL-6) mRNA, possibly consistent with mild skeletal muscle injury. Notably, we found that AMPKα1 and AMPKα2 isoforms are dispensable for contraction-induced skeletal muscle glucose transport, except for male soleus muscle. However, the lack of skeletal muscle AMPK diminished maximal ADP-stimulated mitochondrial respiration, showing an impairment at complex I. This effect was not accompanied by changes in mitochondrial number, indicating that AMPK regulates muscle metabolic adaptation through the regulation of muscle mitochondrial oxidative capacity and mitochondrial substrate utilization but not baseline mitochondrial muscle content. Together, these results demonstrate that skeletal muscle AMPK has an unexpected role in the regulation of mitochondrial oxidative phosphorylation that contributes to the energy demands of the exercising muscle.-Lantier, L., Fentz, J., Mounier, R., Leclerc, J., Treebak, J. T., Pehmøller, C., Sanz, N., Sakakibara, I., Saint-Amand, E., Rimbaud, S., Maire, P., Marette, A., Ventura-Clapier, R., Ferry, A., Wojtaszewski, J. F. P., Foretz, M., Viollet, B. AMPK controls exercise endurance, mitochondrial oxidative capacity, and skeletal muscle integrity.
Southern, William M.; Nichenko, Anna S.; Shill, Daniel D.; Spencer, Corey C.; Jenkins, Nathan T.; McCully, Kevin K.
We tested the hypothesis that a 6-week regimen of simvastatin would attenuate skeletal muscle adaptation to low-intensity exercise. Male C57BL/6J wildtype mice were subjected to 6-weeks of voluntary wheel running or normal cage activities with or without simvastatin treatment (20 mg/kg/d, n = 7–8 per group). Adaptations in in vivo fatigue resistance were determined by a treadmill running test, and by ankle plantarflexor contractile assessment. The tibialis anterior, gastrocnemius, and plantaris muscles were evaluated for exercised-induced mitochondrial adaptations (i.e., biogenesis, function, autophagy). There was no difference in weekly wheel running distance between control and simvastatin-treated mice (P = 0.51). Trained mice had greater treadmill running distance (296%, P<0.001), and ankle plantarflexor contractile fatigue resistance (9%, P<0.05) compared to sedentary mice, independent of simvastatin treatment. At the cellular level, trained mice had greater mitochondrial biogenesis (e.g., ~2-fold greater PGC1α expression, P<0.05) and mitochondrial content (e.g., 25% greater citrate synthase activity, P<0.05), independent of simvastatin treatment. Mitochondrial autophagy-related protein contents were greater in trained mice (e.g., 40% greater Bnip3, P<0.05), independent of simvastatin treatment. However, Drp1, a marker of mitochondrial fission, was less in simvastatin treated mice, independent of exercise training, and there was a significant interaction between training and statin treatment (P<0.022) for LC3-II protein content, a marker of autophagy flux. These data indicate that whole body and skeletal muscle adaptations to endurance exercise training are attainable with simvastatin treatment, but simvastatin may have side effects on muscle mitochondrial maintenance via autophagy, which could have long-term implications on muscle health. PMID:28207880
Komiyama, Takaaki; Sudo, Mizuki; Higaki, Yasuki; Kiyonaga, Akira; Tanaka, Hiroaki; Ando, Soichi
It has been suggested that acute exercise improves cognitive function. However, little is known about how exercise under hypoxia affects cognitive function. The purpose of this study was to determine if hypoxia alters working memory and executive function during prolonged exercise. Sixteen participants performed cognitive tasks at rest and during exercise under normoxia and hypoxia [fraction of inspired oxygen (FIO2)=0.15, corresponding to an altitude of approximately 2600 m]. The level of hypoxia was moderate. We used a combination of Spatial Delayed Response (Spatial DR) task and Go/No-Go (GNG) task, where spatial working memory and executive function are required. Working memory was assessed by the accuracy of the Spatial DR task, and executive function was assessed by the accuracy and reaction time in the GNG task. The participants cycled an ergometer for 30 min under normoxia and moderate hypoxia while keeping their heart rate (HR) at 140 beats/min. They performed the cognitive tasks 5 min and 23 min after their HR reached 140 beats/min. Moderate hypoxia did not alter the accuracy of the Spatial DR (P=0.38) and GNG tasks (P=0.14). In contrast, reaction time in the GNG task significantly decreased during exercise relative to rest under normoxia and moderate hypoxia (P=0.02). These results suggest that moderate hypoxia and resultant biological processes did not provide sufficient stress to impair working memory and executive function during prolonged exercise. The beneficial effects on speed of response appear to persist during prolonged exercise under moderate hypoxia.
Young, Jeremy C; Dowell, Nicholas G; Watt, Peter W; Tabet, Naji; Rusted, Jennifer M
While there is evidence that age-related changes in cognitive performance and brain structure can be offset by increased exercise, little is known about the impact long-term high-effort endurance exercise has on these functions. In a cross-sectional design with 12-month follow-up, we recruited older adults engaging in high-effort endurance exercise over at least 20 years, and compared their cognitive performance and brain structure with a nonsedentary control group similar in age, sex, education, IQ, and lifestyle factors. Our findings showed no differences on measures of speed of processing, executive function, incidental memory, episodic memory, working memory, or visual search for older adults participating in long-term high-effort endurance exercise, when compared without confounds to nonsedentary peers. On tasks that engaged significant attentional control, subtle differences emerged. On indices of brain structure, long-term exercisers displayed higher white matter axial diffusivity than their age-matched peers, but this did not correlate with indices of cognitive performance.
Risøy, Bjørn Audun; Raastad, Truls; Hallén, Jostein; Lappegård, Knut T; Bæverfjord, Kjersti; Kravdal, Astrid; Siebke, Else Marie; Benestad, Haakon B
Background During infections, polymorphonuclear neutrophilic granulocytes (PMN) are mobilized from their bone marrow stores, travel with blood to the affected tissue, and kill invading microbes there. The signal(s) from the inflammatory site to the marrow are unknown, even though a number of humoral factors that can mobilize PMN, are well known. We have employed a standardized, non-infectious human model to elucidate relevant PMN mobilizers. Well-trained athletes performed a 60-min strenuous strength workout of leg muscles. Blood samples were drawn before, during and just after exercise, and then repeatedly during the following day. Cortisol, GH, ACTH, complement factors, high-sensitive CRP (muCRP), IL-6, G-CSF, IL-8 (CXCL8) and MIP-1β (CCL4) were measured in blood samples. PMN chemotaxins in test plasma was assessed with a micropore membrane technique. Results About 5 hr after the workout, blood granulocytosis peaked to about 150% of baseline. Plasma levels of GH increased significantly 30 min into and 5 min after the exercise, but no increase was recorded for the other hormones. No significant correlation was found between concentrations of stress hormones and the subjects' later occurring PMN increases above their individual baselines. Plasma G-CSF increased significantly – but within the normal range – 65 min after the workout. IL-6 increased very slightly within the normal range, and the chemokines IL-8 and MIP-1β did not increase consistently. However, we found a significant increase of hitherto non-identified PMN-chemotactic activity in plasma 35, 50, and 60 min after the exercise. No systemic complement activation was detected, and (mu)CRP was within the reference range at rest, 5 h and 23 h after the exercise. After endurance exercise, similar findings were made, except for a cortisol response, especially from non-elite runners. Conclusion Apparently, a multitude of humoral factors can – directly or indirectly – mobilize PMN from marrow to blood
Guenette, Jordan A; Romer, Lee M; Querido, Jordan S; Chua, Romeo; Eves, Neil D; Road, Jeremy D; McKenzie, Donald C; Sheel, A William
There is evidence that female athletes may be more susceptible to exercise-induced arterial hypoxemia and expiratory flow limitation and have greater increases in operational lung volumes during exercise relative to men. These pulmonary limitations may ultimately lead to greater levels of diaphragmatic fatigue in women. Accordingly, the purpose of this study was to determine whether there are sex differences in the prevalence and severity of exercise-induced diaphragmatic fatigue in 38 healthy endurance-trained men (n = 19; maximal aerobic capacity = 64.0 +/- 1.9 ml x kg(-1) x min(-1)) and women (n = 19; maximal aerobic capacity = 57.1 +/- 1.5 ml x kg(-1) x min(-1)). Transdiaphragmatic pressure (Pdi) was calculated as the difference between gastric and esophageal pressures. Inspiratory pressure-time products of the diaphragm and esophagus were calculated as the product of breathing frequency and the Pdi and esophageal pressure time integrals, respectively. Cervical magnetic stimulation was used to measure potentiated Pdi twitches (Pdi,tw) before and 10, 30, and 60 min after a constant-load cycling test performed at 90% of peak work rate until exhaustion. Diaphragm fatigue was considered present if there was a >or=15% reduction in Pdi,tw after exercise. Diaphragm fatigue occurred in 11 of 19 men (58%) and 8 of 19 women (42%). The percent drop in Pdi,tw at 10, 30, and 60 min after exercise in men (n = 11) was 30.6 +/- 2.3, 20.7 +/- 3.2, and 13.3 +/- 4.5%, respectively, whereas results in women (n = 8) were 21.0 +/- 2.1, 11.6 +/- 2.9, and 9.7 +/- 4.2%, respectively, with sex differences occurring at 10 and 30 min (P < 0.05). Men continued to have a reduced contribution of the diaphragm to total inspiratory force output (pressure-time product of the diaphragm/pressure-time product of the esophagus) during exercise, whereas diaphragmatic contribution in women changed very little over time. The findings from this study point to a female diaphragm that is more resistant
van Loon, Luc J C; Tipton, Kevin D
Nutrition plays a key role in allowing the numerous training hours to be translated into useful adaptive responses of various tissues in the individual athlete. Research over the last decade has shown many examples of the impact of dietary interventions to modulate the skeletal muscle adaptive response to prolonged exercise training. Proper nutritional coaching should be applied throughout both training and competition, each with their specific requirements regarding nutrient provision. Such dietary support will improve exercise training efficiency and, as such, further increase performance capacity. Here, we provide an overview on the properties of various nutritional interventions that may be useful to support the adaptive response to exercise training and competition and, as such, to augment exercise training efficiency.
Diman, Aurélie; Boros, Joanna; Poulain, Florian; Rodriguez, Julie; Purnelle, Marin; Episkopou, Harikleia; Bertrand, Luc; Francaux, Marc; Deldicque, Louise; Decottignies, Anabelle
DNA breaks activate the DNA damage response and, if left unrepaired, trigger cellular senescence. Telomeres are specialized nucleoprotein structures that protect chromosome ends from persistent DNA damage response activation. Whether protection can be enhanced to counteract the age-dependent decline in telomere integrity is a challenging question. Telomeric repeat–containing RNA (TERRA), which is transcribed from telomeres, emerged as important player in telomere integrity. However, how human telomere transcription is regulated is still largely unknown. We identify nuclear respiratory factor 1 and peroxisome proliferator–activated receptor γ coactivator 1α as regulators of human telomere transcription. In agreement with an upstream regulation of these factors by adenosine 5′-monophosphate (AMP)–activated protein kinase (AMPK), pharmacological activation of AMPK in cancer cell lines or in normal nonproliferating myotubes up-regulated TERRA, thereby linking metabolism to telomere fitness. Cycling endurance exercise, which is associated with AMPK activation, increased TERRA levels in skeletal muscle biopsies obtained from 10 healthy young volunteers. The data support the idea that exercise may protect against aging. PMID:27819056
Jeong, Ji-Woong; Shim, Jae-Jung; Choi, Il-Dong; Kim, Sung-Hwan; Ra, Jehyeon; Ku, Hyung Keun; Lee, Dong Eun; Kim, Tae-Youl; Jeung, Woonhee; Lee, Jung-Hee; Lee, Ki Won; Huh, Chul-Sung; Sim, Jae-Hun; Ahn, Young-Tae
Ursolic acid is a lipophilic pentacyclic triterpenoid found in many fruits and herbs and is used in several herbal folk medicines for diabetes. In this study, we evaluated the effects of apple pomace extract (APE; ursolic acid content, 183 mg/g) on skeletal muscle atrophy. To examine APE therapeutic potential in muscle atrophy, we investigated APE effects on the expression of biomarkers associated with muscle atrophy and hypertrophy. We found that APE inhibited atrophy, while inducing hypertrophy in C2C12 myotubes by decreasing the expression of atrophy-related genes and increasing the expression of hypertrophy-associated genes. The in vivo experiments using mice fed a diet with or without APE showed that APE intake increased skeletal muscle mass, as well as grip strength and exercise capacity. In addition, APE significantly improved endurance in the mice, as evidenced by increased exhaustive running time and muscle weight, and reduced the expression of the genes involved in the development of muscle atrophy. APE also decreased the concentration of serum lactate and lactate dehydrogenase, inorganic phosphate, and creatinine, the indicators of accumulated fatigue and exercise-induced stress. These results suggest that APE may be useful as an ergogenic functional food or dietary supplement.
Pierce, Gary L.; Harris, Stephen A.; Seals, Douglas R.; Casey, Darren P.; Barlow, Patrick B.; Stauss, Harald M.
We hypothesized that differences in cardiac baroreflex sensitivity (BRS) would be independently associated with aortic stiffness and augmentation index (AI), clinical biomarkers of cardiovascular disease (CVD) risk, among young sedentary and middle-aged/older sedentary and endurance-trained adults. A total of 36 healthy middle-aged/older (age 55-76 years, n=22 sedentary; n=14 endurance-trained) and 5 young sedentary (age 18-31 years) adults were included in a cross-sectional study. A subset of the middle-aged/older sedentary adults (n=12) completed an 8-week aerobic exercise intervention. Invasive brachial artery blood pressure waveforms were used to compute spontaneous cardiac BRS (via sequence technique) and estimated aortic pulse wave velocity (PWV) and AI (AI, via brachial-aortic transfer function and wave separation analysis). In the cross-sectional study, cardiac BRS was 71% lower in older compared with young sedentary adults (P<0.05), but only 40% lower in older adults who performed habitual endurance exercise (P=0.03). In a regression model that included age, sex, resting heart rate, mean arterial pressure (MAP), body mass index and maximal exercise oxygen uptake, estimated aortic PWV (β±SE = −5.76 ± 2.01, P=0.01) was the strongest predictor of BRS (Model R2=0.59, P<0.001). The 8 week exercise intervention improved BRS by 38% (P=0.04) and this change in BRS was associated with improved aortic PWV (r=−0.65, P=0.044, adjusted for changes in MAP). Age- and endurance exercise-related differences in cardiac BRS are independently associated with corresponding alterations in aortic PWV among healthy adults, consistent with a mechanistic link between variations in the sensitivity of the baroreflex and aortic stiffness with age and exercise. PMID:26911535
Background Almonds are a healthy tree nut food with high nutrient density. Their consumption has been shown to ameliorate oxidative stress, inflammation, etc. The objective of the study was to examine the effect of almonds on elements of endurance exercise performance in trained athletes. Methods A 10-week crossover, placebo controlled study was conducted. Eight trained male cyclists and two triathletes were randomly assigned to consume 75 g/d whole almonds (ALM) or isocaloric cookies (COK) with equal subject number. They consumed the assigned food for 4 wks and then the alternate food for another 4 wks. They underwent 3 performance tests including 125-min steady status exercise (SS) and 20-min time trial (TT) on an indoor stationary trainer at the start of the study (BL) and at the end of each intervention phase. Venous blood was collected in the morning prior to the performance test for biochemical measurements and finger blood during the test for glucose determination. Carbohydrate and fat oxidation, energy expenditure, and oxygen use were calculated using respiratory gas analysis. Results ALM increased cycling distance during TT by 1.7 km as compared BL (21.9 vs. 20.2 km, P = 0.053) and COK increased 0.6 km (20.8 vs. 20.2 km, P > 0.05). ALM, but not COK, led to higher CHO and lower fat oxidation and less oxygen consumption during TT than BL (P < 0.05), whereas there was no significant difference in heart rate among BL, ALM and COK. ALM maintained higher blood glucose level after TT than COK (P < 0.05). ALM had higher vitamin E and haemoglobin and lower serum free fatty acid (P < 0.05), slightly elevated serum arginine and nitric oxide and plasma insulin (P > 0.05) than BL, and a higher total antioxidant capacity than COK (P < 0.05). Conclusions Whole almonds improved cycling distance and the elements related to endurance performance more than isocaloric cookies in trained athletes as some nutrients in almonds may contribute to
Nazar, K.; Greenleaf, J. E.; Philpott, D.; Pohoska, E.; Olszewska, K.; Kaciuba-Uscilko, H.
The effect of exhaustive treadmill exercise on ultrastructural changes in the quadriceps femoris muscle was studied in 7 normal, healthy dogs, before and after restricted activity (RA), and following a subsequent 2 month treadmill exercise retraining period for the 5 mo group. Mean time to exhaustion in the 2 mo group decreased from 177 + or - 22 min before to 90 + or - 32 min after RA. Retraining increased tolerance to 219 + or - 73 min; 24 pct. above the before RA and 143 pct. above the after RA time. After RA exhaustion time in the 5 mo group was 25 and 45 min. Before RA, pre-exercise muscle structure was normal and post exercise there was only slight swelling of mitochondria. After RA, pre-exercise, numerous glycogen granules and lipid droplets appeared in the muscle fibers, mitochondria were smaller, and sarcoplasmic reticulum channels widened; post exercise these changes were accentuated and some areas were devoid of glycogen, and there was fiber degradation. After 5 mo RA pre-exercise there were more pronounced changes; mitochondria were very small and dense, there were many lipid droplets, myofibrils were often separated, and the fibers appeared edematous and degenerating; post exercise the sarcoplasmic reticulum was swollen, no glycogen was present, and there was marked swelling and deformation of mitochondria. After retraining, both pre-exercise and post exercise there was still evidence of fiber degeneration. Thus, susceptibility of active skeletal muscle structures and subcellular elements, e.g., mitochondria, to the action of damaging factors occurring during exhaustive exercise is enhanced considerably by prolonged disuse.
Zaleski, Amanda; Capizzi, Jeffrey; Ballard, Kevin D.; Troyanos, Christopher; Baggish, Aaron; D'Hemecourt, Pierre; Thompson, Paul D.; Parker, Beth
Strenuous endurance exercise increases inflammatory markers and acutely increases cardiovascular risk; however, statins may mitigate this response. We measured serum levels of p-selectin in 37 runners treated with statins and in 43 nonstatin treated controls running the 2011 Boston Marathon. Venous blood samples were obtained the day before (PRE) as well as within 1 hour after (FINISH) and 24 hours after (POST) the race. The increase in p-selectin immediately after exercise was lower in statin users (PRE to FINISH: 20.5 ± 19.4 ng/mL) than controls (PRE to FINISH: 30.9 ± 27.1 ng/mL; P < 0.001). The increase in p-selectin 24 hours after exercise was also lower in statin users (PRE to POST: 21.5 ± 26.6 ng/mL) than controls (PRE to POST: 29.3 ± 31.9 ng/mL; P < 0.001). Furthermore, LDL-C was positively correlated with p-selectin at FINISH and POST (P < 0.01 and P < 0.05, resp.), irrespective of drug treatment, suggesting that lower levels of LDL-C are associated with a reduced inflammatory response to exercise. We conclude that statins blunt the exercise-induced increase in p-selectin following a marathon and that the inflammatory response to a marathon varies directly with LDL-C levels. PMID:26464882
Lee, Hyo Taek; Roh, Hyo Lyun; Kim, Yoon Sang
[Purpose] Efficient management using exercise programs with various benefits should be provided by educational institutions for children in their growth phase. We analyzed the heart rates of children during ski simulator exercise and the Harvard step test to evaluate the cardiopulmonary endurance by calculating their post-exercise recovery rate. [Subjects and Methods] The subjects (n = 77) were categorized into a normal weight and an overweight/obesity group by body mass index. They performed each exercise for 3 minutes. The cardiorespiratory endurance was calculated using the Physical Efficiency Index formula. [Results] The ski simulator and Harvard step test showed that there was a significant difference in the heart rates of the 2 body mass index-based groups at each minute. The normal weight and the ski-simulator group had higher Physical Efficiency Index levels. [Conclusion] This study showed that a simulator exercise can produce a cumulative load even when performed at low intensity, and can be effectively utilized as exercise equipment since it resulted in higher Physical Efficiency Index levels than the Harvard step test. If schools can increase sport durability by stimulating students' interests, the ski simulator exercise can be used in programs designed to improve and strengthen students' physical fitness.
Lee, Hyo Taek; Roh, Hyo Lyun; Kim, Yoon Sang
[Purpose] Efficient management using exercise programs with various benefits should be provided by educational institutions for children in their growth phase. We analyzed the heart rates of children during ski simulator exercise and the Harvard step test to evaluate the cardiopulmonary endurance by calculating their post-exercise recovery rate. [Subjects and Methods] The subjects (n = 77) were categorized into a normal weight and an overweight/obesity group by body mass index. They performed each exercise for 3 minutes. The cardiorespiratory endurance was calculated using the Physical Efficiency Index formula. [Results] The ski simulator and Harvard step test showed that there was a significant difference in the heart rates of the 2 body mass index-based groups at each minute. The normal weight and the ski-simulator group had higher Physical Efficiency Index levels. [Conclusion] This study showed that a simulator exercise can produce a cumulative load even when performed at low intensity, and can be effectively utilized as exercise equipment since it resulted in higher Physical Efficiency Index levels than the Harvard step test. If schools can increase sport durability by stimulating students’ interests, the ski simulator exercise can be used in programs designed to improve and strengthen students’ physical fitness. PMID:27065556
Fagard, R H
blood pressure of 3.5 mmHg (P < 0.01) associated with exercise and a non-significant reduction of systolic blood pressure of 3.2 mmHg (P = 0.10). 5. In conclusion, dynamic aerobic endurance training decreases blood pressure through a reduction of systemic vascular resistance, in which the sympathetic nervous system and the renin-angiotensin system appear to be involved, and favourably affects concomitant cardiovascular risk factors. In addition, the few available data suggest that resistance training is able to reduce blood pressure.
Gunzer, Wolfgang; Konrad, Manuela; Pail, Elisabeth
Heavily exercising endurance athletes experience extreme physiologic stress, which is associated with temporary immunodepression and higher risk of infection, particularly upper respiratory tract infections (URTI). The aim of this review is to provide a critical up-to-date review of existing evidence on the immunomodulatory potential of selected macronutrients and to evaluate their efficacy. The results of 66 placebo-controlled and/or crossover trials were compared and analysed. Among macronutrients, the most effective approach to maintain immune function in athletes is to consume ≥6% carbohydrate during prolonged exercise. Because inadequate nutrition affects almost all aspects of the immune system, a well-balanced diet is also important. Evidence of beneficial effects from other macronutrients is scarce and results are often inconsistent. Using a single nutrient may not be as effective as a mixture of several nutritional supplements. Due to limited research evidence, with the exception of carbohydrate, no explicit recommendations to reduce post-exercise URTI symptoms with single macronutrients can be derived.
Buraczewska, M; Miśkiewicz, Z; Dąbrowski, J; Steczkowska, M; Kozacz, A; Ziemba, A
The purpose of this study was to investigate the effect of ultra-endurance exercise on left ventricular (LV) performance and plasma concentration of interleukin (IL)-6, IL-10, IL-18 and tumour necrosis factor alpha (TNF-α) as well as to examine the relationships between exercise-induced changes in plasma cytokines and those in echocardiographic indices of LV function in ultra-marathon runners. Nine healthy trained men (mean age 30±1.0 years) participated in a 100-km ultra-marathon. Heart rate, blood pressure, ejection fraction (EF), fractional shortening (FS), ratio of early (E) to late (A) mitral inflow peak velocities (E/A), ratio of early (E’) to late (A’) diastolic mitral annulus peak velocities (E’/A’) and E-wave deceleration time (DT) were obtained by echocardiography before, immediately after and in the 90th minute of the recovery period. Blood samples were taken before each echocardiographic evaluation. The ultra-endurance exercise caused significant increases in plasma IL-6, IL-10, IL-18 and TNF-α. Echocardiography revealed significant decreases in both E and the E/A ratio immediately after exercise, without any significant changes in EF, FS, DT or the E/E’ ratio. At the 90th minute of the recovery period, plasma TNF-α and the E/A ratio did not differ significantly from the pre-exercise values, whereas FS was significantly lower than before and immediately after exercise. The increases in plasma TNF-α correlated with changes in FS (r=0.73) and DT (r=-0.73). It is concluded that ultra-endurance exercise causes alterations in LV diastolic function. The present data suggest that TNF-α might be involved in this effect. PMID:26985136
Stavrianeas, Stasinos; Spangenburg, Espen; Batts, Tim; Williams, Jay H; Klug, Gary A
The effects of a single bout of prolonged treadmill exercise [mean=81 (13) min] on sarcoplasmic reticulum (SR) Ca(2+) release, uptake and ATPase activity were determined in the costal region of rat diaphragm (D) and red gastrocnemius (RG). Glycogen depletion measurements made immediately following exercise suggested that treadmill running substantially recruited the fibers throughout both muscles. SR Ca(2+) ATPase activity, measured in isolated SR vesicles, decreased in the RG by 33% but remained unchanged in D in response to the exercise bout. This effect in RG was matched by a 37% decline in Ca(2+) uptake and a 28% depression in Ca(2+) release when measured in muscle homogenates. Conversely, Ca(2+) uptake increased between 157% and 263% in the D in the absence of any change in Ca(2+) release. These data show that the attenuation of SR function that has been consistently observed in limb muscle over the last several decades is absent in diaphragm despite the fact that its fibers appear to experience sufficient activity to deplete their glycogen. In fact, the large increase in Ca(2+) uptake in D shows that prolonged activity actually potentiates the ability of SR vesicles to sequester Ca(2+) in the absence of any increase in energy cost. Thus, it appears necessary to re-evaluate the role of exercise in regulating Ca(2+) sequestration by the SR as different muscles may respond in ways that are dictated by their function.
Scoppetta, Fausto; Tartaglia, Micaela; Renzone, Giovanni; Avellini, Luca; Gaiti, Alberto; Scaloni, Andrea; Chiaradia, Elisabetta
Physical exercise induces various stress responses and metabolic adaptations that have not yet been completely elucidated. Novel biomarkers are needed in sport veterinary medicine to monitor training levels and to detect subclinical conditions that can develop into exercise-related diseases. In this study, protein modifications in horse plasma induced by prolonged, aerobic physical exercise were investigated by using a proteomic approach based on 2-DE and combined mass spectrometry procedures. Thirty-eight protein spots, associated with expression products of 13 genes, showed significant quantitative changes; spots identified as membrane Cu amine oxidase, α-1 antitrypsin, α-1 antitrypsin-related protein, caeruloplasmin, α-2 macroglobulin and complement factor C4 were augmented in relative abundance after the race, while haptoglobin β chain, apolipoprotein A-I, transthyretin, retinol binding protein 4, fibrinogen γ chain, complement factor B and albumin fragments were reduced. These results indicate that prolonged physical exercise affects plasma proteins involved in pathways related to inflammation, coagulation, immune modulation, oxidant/antioxidant activity and cellular and vascular damage, with consequent effects on whole horse metabolism.
Burgomaster, Kirsten A; Howarth, Krista R; Phillips, Stuart M; Rakobowchuk, Mark; Macdonald, Maureen J; McGee, Sean L; Gibala, Martin J
Low-volume 'sprint' interval training (SIT) stimulates rapid improvements in muscle oxidative capacity that are comparable to levels reached following traditional endurance training (ET) but no study has examined metabolic adaptations during exercise after these different training strategies. We hypothesized that SIT and ET would induce similar adaptations in markers of skeletal muscle carbohydrate (CHO) and lipid metabolism and metabolic control during exercise despite large differences in training volume and time commitment. Active but untrained subjects (23 +/- 1 years) performed a constant-load cycling challenge (1 h at 65% of peak oxygen uptake (.VO(2peak)) before and after 6 weeks of either SIT or ET (n = 5 men and 5 women per group). SIT consisted of four to six repeats of a 30 s 'all out' Wingate Test (mean power output approximately 500 W) with 4.5 min recovery between repeats, 3 days per week. ET consisted of 40-60 min of continuous cycling at a workload that elicited approximately 65% (mean power output approximately 150 W) per day, 5 days per week. Weekly time commitment (approximately 1.5 versus approximately 4.5 h) and total training volume (approximately 225 versus approximately 2250 kJ week(-1)) were substantially lower in SIT versus ET. Despite these differences, both protocols induced similar increases (P < 0.05) in mitochondrial markers for skeletal muscle CHO (pyruvate dehydrogenase E1alpha protein content) and lipid oxidation (3-hydroxyacyl CoA dehydrogenase maximal activity) and protein content of peroxisome proliferator-activated receptor-gamma coactivator-1alpha. Glycogen and phosphocreatine utilization during exercise were reduced after training, and calculated rates of whole-body CHO and lipid oxidation were decreased and increased, respectively, with no differences between groups (all main effects, P < 0.05). Given the markedly lower training volume in the SIT group, these data suggest that high-intensity interval training is a time
Nieman, D C; Nehlsen-Cannarella, S L; Fagoaga, O R; Henson, D A; Utter, A; Davis, J M; Williams, F; Butterworth, D E
The influence of exercise mode and 6% carbohydrate (C) vs. placebo (P) beverage ingestion on granulocyte and monocyte phagocytosis and oxidative burst activity (GMPOB) after prolonged and intensive exertion was measured in 10 triathletes. The triathletes acted as their own controls and ran or cycled for 2.5 h at approximately 75% maximal O2 uptake, ingesting C or P (4 total sessions, random order, with beverages administered in double-blind fashion). During the 2. 5-h exercise bouts, C or P (4 ml/kg) was ingested every 15 min. Five blood samples were collected (15 min before exercise, immediately after exercise, and 1.5, 3, and 6 h after exercise). The pattern of change over time for GMPOB was significantly different between C and P conditions (P = 0.05), with postexercise values lower during the C trials. Little difference was measured between running and cycling modes. C relative to P ingestion (but not exercise mode) was associated with higher plasma levels of glucose and insulin, lower plasma levels of cortisol and growth hormone, and lower blood neutrophil and monocyte cell counts. These data indicate that C vs. P ingestion is associated with higher plasma glucose levels, an attenuated cortisol response, and lower GMPOB.
Tesch, P A; Karlsson, J
Five elite flatwater kayak paddlers were studied during indoor simulated 500 and 10,000-m races, with performance times of 2 and 45 min, respectively. Muscle biopsies were obtained from the midportion of m. deltoideus immediately pre and post exercise. Concentrations of adenosine triphosphate (ATP), creatine phosphate (CP), glucose, glucose-6-phosphate (G-6-P), glycogen, and lactate were subsequently determined. Short term exercise resulted in statistically significant increases in glucose (P less than 0.001), G-6-P (P less than 0.05) and lactate (P less than 0.01) concentration concomitant with decreased CP (P less than 0.05) and glycogen (P less than 0.01). Following prolonged exercise, a non-significant elevation in glucose and a reduction (P less than 0.01) in glycogen were demonstrated. Evidently the metabolic demands for kayak competitions at 500 and 10,000 m are different. Thus, the energy contribution from glycolytic precursors and the anaerobic component is of greater relative importance in short distances than in exercise of long duration. A generalization of the findings to other athletic events of varying distances is proposed. The present data on arm-exercise is consistent with previous findings obtained in connection with leg exercises.
Trinity, Joel D; Pahnke, Matthew D; Lee, Joshua F; Coyle, Edward F
People who become hyperthermic during exercise display large increases in heart rate (HR) and reductions in stroke volume (SV). It is not clear if the reduction in SV is due primarily to hyperthermia or if it is a secondary effect of an elevation in HR reducing ventricular filling. In the present study, the upward drift of HR during prolonged exercise was prevented by a very small dose of the β1-adrenoreceptor blocker (atenolol; βB), thus allowing SV to be compared at a given HR during normothermia and hyperthermia. Eleven men cycled for 60 min at 57% of peak O2 uptake after receiving placebo control (PL) or a low dose (0.2 mg/kg) of βB. Hyperthermia was induced by reducing heat dissipation during exercise. Four experimental conditions were studied: normothermia-PL, normothermia-βB, hyperthermia-PL, and hyperthermia-βB. Hyperthermia increased skin and core temperature by 4.3 degrees C and 0.8 degrees C (P<0.01), respectively. βB prevented HR elevation with hyperthermia: HR values were similar at minute 60 during normothermia-PL and hyperthermia-βB (155±11 and 154±13 beats/min, respectively, P=0.82). However, SV was increased by 7% during the final 20 min of exercise during hyperthermia-βB compared with normothermia-PL (treatment×time interaction, P=0.03). In conclusion, when matched for HR, mild hyperthermia increased SV during exercise. Furthermore, the reduction in SV throughout prolonged exercise under normothermic and mildly hyperthermic conditions appears to be due to the increase in HR.
Al-Jarrah, M; Pothakos, K; Novikova, L; Smirnova, I V; Kurz, M J; Stehno-Bittel, L; Lau, Y-S
Physical rehabilitation with endurance exercise for patients with Parkinson's disease has not been well established, although some clinical and laboratory reports suggest that exercise may produce a neuroprotective effect and restore dopaminergic and motor functions. In this study, we used a chronic mouse model of Parkinsonism, which was induced by injecting male C57BL/6 mice with 10 doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (25 mg/kg) and probenecid (250 mg/kg) over 5 weeks. This chronic parkinsonian model displays a severe and persistent loss of nigrostriatal neurons, resulting in robust dopamine depletion and locomotor impairment in mice. Following the induction of Parkinsonism, these mice were able to sustain an exercise training program on a motorized rodent treadmill at a speed of 18 m/min, 0 degrees of inclination, 40 min/day, 5 days/week for 4 weeks. At the end of exercise training, we examined and compared their cardiorespiratory capacity, behavior, and neurochemical changes with that of the probenecid-treated control and sedentary parkinsonian mice. The resting heart rate after 4 weeks of exercise in the chronic parkinsonian mice was significantly lower than the rate before exercise, whereas the resting heart rate at the beginning and 4 weeks afterward in the control or sedentary parkinsonian mice was unchanged. Exercised parkinsonian mice also recovered from elevated electrocardiogram R-wave amplitude that was detected in the parkinsonian mice without exercise for 4 weeks. The values of oxygen consumption, carbon dioxide production, and body heat generation in the exercised parkinsonian mice before and during the Bruce maximal exercise challenge test were all significantly lower than that of their sedentary counterparts. Furthermore, the exercised parkinsonian mice demonstrated a greater mass in the left ventricle of the heart and an increased level of citrate synthase activity in the skeletal muscles. The amphetamine-induced, dopamine
Mitchell, Joel B; Rogers, Melissa M; Basset, John T; Hubing, Kimberly A
The purpose of this study was to examine the effects of hot (37° C) and cool (10° C) environments on cycling time to exhaustion (TTE), pH, lactate, and core temperature (Tc). Eleven endurance-trained subjects completed 4 TTE trials: Hot 80% VO2max (H80), Cool 80% (C80), Hot 100% (H100), and Cool 100% VO2max (C100). Esophageal temperature and blood was sampled before, every 5 minutes, at exhaustion, and 3 minutes after exercise and analyzed for lactate, pH, and HCO3-. Multifactorial analysis of variance with repeated measures was used to determine differences between mean values (± SD). Time to exhaustion was shorter in H100 and C100 vs. H80 and C80 (5.64 ± 1.49 minutes, 5.83 ± 1.03 minutes, 12.82 ± 2.0 minutes, and 24.85 ± 6.0 minutes, respectively) and shorter in H80 vs. C80 (p < 0.01). The pH at exhaustion was different among all conditions (7.17 ± 0.06, 7.15 ± 0.07, 7.21 ± 0.04, and 7.24 ± 0.06 units for H100, C100, H80, and C80, respectively, p = 0.02). The Tc at exhaustion was lower in H100 and C100 (37.93 ± 0.67 and 37.62 ± 0.58° C) vs. H80 and C80 (38.54 ± 0.51° C and 38.53 ± 0.38° C) (p < 0.01). In H80 and C80, the higher Tc likely played a greater role in the termination of exercise, whereas, in H100 and C100, pH and metabolic changes may have been more important. Despite these differences, neither an upper limit for Tc nor a lower limit for pH was identified; thus, fatigue based entirely on peripheral factors was not supported, and a combination of peripheral and central processes must be considered. The practical implications of these findings are that aerobic exercise at or near VO2max may be impacted more by metabolic factors, whereas lower intensities (∼80% VO2max) may be affected more by heat stress; these differences should be considered when training for events of this type.
Kang, E-B; Koo, J-H; Jang, Y-C; Yang, C-H; Lee, Y; Cosio-Lima, L M; Cho, J-Y
Obesity contributes to systemic inflammation, which is associated with the varied pathogenesis of neurodegenerative diseases. Growing evidence has demonstrated that endurance exercise (EE) mitigates obesity-induced brain inflammation. However, exercise-mediated anti-inflammatory mechanisms remain largely unknown. We investigated how treadmill exercise (TE) reverses obesity-induced brain inflammation, mainly focusing on toll-like receptor-4 (TLR-4)-dependent neuroinflammation in the obese rat brain after 20 weeks of a high-fat diet (HFD). TE in HFD-fed rats resulted in a significant lowering in the homeostasis model assessment of insulin resistance index, the area under the curve for glucose and abdominal visceral fat, and also improved working memory ability in a passive avoidance task relative to sedentary behaviour in HFD-fed rats, with the exception of body weight. More importantly, TE revoked the increase in HFD-induced proinflammatory cytokines (tumour necrosis factor α and interleukin-1β) and cyclooxygenase-2, which is in parallel with a reduction in TLR-4 and its downstream proteins, myeloid differentiation 88 and tumour necrosis factor receptor associated factor 6, and phosphorylation of transforming growth factor β-activated kinase 1, IkBα and nuclear factor-κB. Moreover, TE reduced an indicator of microglia activation, ionised calcium-binding adapter molecule-1, and also decreased glial fibrillary acidic protein, an indicator of gliosis formed by activated astrocytes in the cerebral cortex and the hippocampal dentate gyrus, compared to HFD-fed sedentary rats. Finally, EE up-regulated the expression of anti-apoptotic protein, Bcl-2, and suppressed the expression of pro-apoptotic protein, Bax, in the hippocampus compared to HFD-fed sedentary rats. Taken together, these data suggest that TE may exert neuroprotective effects as a result of mitigating the production of proinflammatory cytokines by inhibiting the TLR4 signalling pathways. The results of
Anderson, Paul J; Wang, Zhen; Beebe, Timothy J; Murad, Mohammad Hassan
Objectives Regular exercise is a key component of obesity prevention and 48% of Americans do not meet minimum guidelines for weekly exercise. Social support has been shown to help individuals start and maintain exercise programmes. We evaluated social support among endurance athletes and explored the relationship between social support for exercise, health behaviours and health status. Design Survey. Setting The largest Nordic ski race in North America. Participants 5433 past participants responded to an online questionnaire. Outcome measures Social support, health behaviours and health status. Results The mean overall support score was 32.1 (SD=16.5; possible range=−16.0 to 88.0). The most common forms of social support were verbal such as discussing exercise, invitations to exercise and celebrating the enjoyment of exercise. We found that an increase of 10 points in the social support score was associated with a 5 min increase in weekly self-reported exercise (5.02, 95% CI 3.63 to 6.41). Conclusions Physical activity recommendations should incorporate the importance of participation in group activities, especially those connected to strong fitness cultures created by community and competitive events. PMID:27338876
Jenkins, Nathan T; Landers, Rian Q; Thakkar, Sunny R; Fan, Xiaoxuan; Brown, Michael D; Prior, Steven J; Spangenburg, Espen E; Hagberg, James M
Abstract We hypothesized that prior exercise would prevent postprandial lipaemia (PPL)-induced increases in intracellular reactive oxygen species (ROS) in three distinct circulating angiogenic cell (CAC) subpopulations. CD34+, CD31+/CD14−/CD34−, and CD31+/CD14+/CD34− CACs were isolated from blood samples obtained from 10 healthy men before and 4 h after ingesting a high fat meal with or without ∼50 min of prior endurance exercise. Significant PPL-induced increases in ROS production in both sets of CD31+ cells were abolished by prior exercise. Experimental ex vivo inhibition of NADPH oxidase activity and mitochondrial ROS production indicated that mitochondria were the primary source of PPL-induced oxidative stress. The attenuated increases in ROS with prior exercise were associated with increased antioxidant gene expression in CD31+/CD14−/CD34− cells and reduced intracellular lipid uptake in CD31+/CD14+/CD34− cells. These findings were associated with systemic cardiovascular benefits of exercise, as serum triglyceride, oxidized low density lipoprotein-cholesterol, and plasma endothelial microparticle concentrations were lower in the prior exercise trial than the control trial. In conclusion, prior exercise completely prevents PPL-induced increases in ROS in CD31+/CD14−/CD34− and CD31+/CD14+/CD34− cells. The mechanisms underlying the effects of exercise on CAC function appear to vary among specific CAC types. PMID:21930598
Baggish, Aaron L; Park, Joseph; Min, Pil-Ki; Isaacs, Stephanie; Parker, Beth A; Thompson, Paul D; Troyanos, Chris; D'Hemecourt, Pierre; Dyer, Sophia; Thiel, Marissa; Hale, Andrew; Chan, Stephen Y
Short nonprotein coding RNA molecules, known as microRNAs (miRNAs), are intracellular mediators of adaptive processes, including muscle hypertrophy, contractile force generation, and inflammation. During basal conditions and tissue injury, miRNAs are released into the bloodstream as "circulating" miRNAs (c-miRNAs). To date, the impact of extended-duration, submaximal aerobic exercise on plasma concentrations of c-miRNAs remains incompletely characterized. We hypothesized that specific c-miRNAs are differentially upregulated following prolonged aerobic exercise. To test this hypothesis, we measured concentrations of c-miRNAs enriched in muscle (miR-1, miR-133a, miR-499-5p), cardiac tissue (miR-208a), and the vascular endothelium (miR-126), as well as those important in inflammation (miR-146a) in healthy male marathon runners (N = 21) at rest, immediately after a marathon (42-km foot race), and 24 h after the race. In addition, we compared c-miRNA profiles to those of conventional protein biomarkers reflective of skeletal muscle damage, cardiac stress and necrosis, and systemic inflammation. Candidate c-miRNAs increased immediately after the marathon and declined to prerace levels or lower after 24 h of race completion. However, the magnitude of change for each c-miRNA differed, even when originating from the same tissue type. In contrast, traditional biomarkers increased after exercise but remained elevated 24 h postexercise. Thus c-miRNAs respond differentially to prolonged exercise, suggesting the existence of specific mechanisms of c-miRNA release and clearance not fully explained by generalized cellular injury. Furthermore, c-miRNA expression patterns differ in a temporal fashion from corollary conventional tissue-specific biomarkers, emphasizing the potential of c-miRNAs as unique, real-time markers of exercise-induced tissue adaptation.
Bell, Phillip G.; Stevenson, Emma; Davison, Gareth W.; Howatson, Glyn
This study investigated Montmorency tart cherry concentrate (MC) supplementation on markers of recovery following prolonged, intermittent sprint activity. Sixteen semi-professional, male soccer players, who had dietary restrictions imposed for the duration of the study, were divided into two equal groups and consumed either MC or placebo (PLA) supplementation for eight consecutive days (30 mL twice per day). On day 5, participants completed an adapted version of the Loughborough Intermittent Shuttle Test (LISTADAPT). Maximal voluntary isometric contraction (MVIC), 20 m Sprint, counter movement jump (CMJ), agility and muscle soreness (DOMS) were assessed at baseline, and 24, 48 and 72 h post-exercise. Measures of inflammation (IL-1-β, IL-6, IL-8, TNF-α, hsCRP), muscle damage (CK) and oxidative stress (LOOH) were analysed at baseline and 1, 3, 5, 24, 48 and 72 h post-exercise. Performance indices (MVIC, CMJ and agility) recovered faster and muscle soreness (DOMS) ratings were lower in the MC group (p < 0.05). Additionally, the acute inflammatory response (IL-6) was attenuated in the MC group. There were no effects for LOOH and CK. These findings suggest MC is efficacious in accelerating recovery following prolonged, repeat sprint activity, such as soccer and rugby, and lends further evidence that polyphenol-rich foods like MC are effective in accelerating recovery following various types of strenuous exercise. PMID:27455316
Bell, Phillip G; Stevenson, Emma; Davison, Gareth W; Howatson, Glyn
This study investigated Montmorency tart cherry concentrate (MC) supplementation on markers of recovery following prolonged, intermittent sprint activity. Sixteen semi-professional, male soccer players, who had dietary restrictions imposed for the duration of the study, were divided into two equal groups and consumed either MC or placebo (PLA) supplementation for eight consecutive days (30 mL twice per day). On day 5, participants completed an adapted version of the Loughborough Intermittent Shuttle Test (LISTADAPT). Maximal voluntary isometric contraction (MVIC), 20 m Sprint, counter movement jump (CMJ), agility and muscle soreness (DOMS) were assessed at baseline, and 24, 48 and 72 h post-exercise. Measures of inflammation (IL-1-β, IL-6, IL-8, TNF-α, hsCRP), muscle damage (CK) and oxidative stress (LOOH) were analysed at baseline and 1, 3, 5, 24, 48 and 72 h post-exercise. Performance indices (MVIC, CMJ and agility) recovered faster and muscle soreness (DOMS) ratings were lower in the MC group (p < 0.05). Additionally, the acute inflammatory response (IL-6) was attenuated in the MC group. There were no effects for LOOH and CK. These findings suggest MC is efficacious in accelerating recovery following prolonged, repeat sprint activity, such as soccer and rugby, and lends further evidence that polyphenol-rich foods like MC are effective in accelerating recovery following various types of strenuous exercise.
Andersson Hall, Ulrika; Edin, Fredrik; Pedersen, Anders; Madsen, Klavs
The purpose of this study was to compare whole-body fat oxidation kinetics after prior exercise with overnight fasting in elite endurance athletes. Thirteen highly trained athletes (9 men and 4 women; maximal oxygen uptake: 66 ± 1 mL·min(-1)·kg(-1)) performed 3 identical submaximal incremental tests on a cycle ergometer using a cross-over design. A control test (CON) was performed 3 h after a standardized breakfast, a fasting test (FAST) 12 h after a standardized evening meal, and a postexercise test (EXER) after standardized breakfast, endurance exercise, and 2 h fasting recovery. The test consisted of 3 min each at 30%, 40%, 50%, 60%, 70%, and 80% of maximal oxygen uptake and fat oxidation rates were measured through indirect calorimetry. During CON, maximal fat oxidation rate was 0.51 ± 0.04 g·min(-1) compared with 0.69 ± 0.04 g·min(-1) in FAST (P < 0.01), and 0.89 ± 0.05 g·min(-1) in EXER (P < 0.01). Across all intensities, EXER was significantly higher than FAST and FAST was higher than CON (P < 0.01). Blood insulin levels were lower and free fatty acid and cortisol levels were higher at the start of EXER compared with CON and FAST (P < 0.05). Plasma nuclear magnetic resonance-metabolomics showed similar changes in both EXER and FAST, including increased levels of fatty acids and succinate. In conclusion, prior exercise significantly increases whole-body fat oxidation during submaximal exercise compared with overnight fasting. Already high rates of maximal fat oxidation in elite endurance athletes were increased by approximately 75% after prior exercise and fasting recovery.
Watson, Phillip; Enever, Sophie; Page, Andrew; Stockwell, Jenna; Maughan, Ronald J
Eight young men were recruited to a study designed to examine the effect of tyrosine (TYR) supplementation on the capacity to perform prolonged exercise in a warm environment. Subjects entered the laboratory in the morning and remained seated for 1 hr before cycling to exhaustion at 70% VO2peak. Two 250-ml aliquots of a placebo (PLA ) or a TYR solution were ingested at 30-min intervals before exercise, with an additional 150 ml consumed every 15 min throughout exercise (total TYR dose: 150 mg/kg BM). Cognitive function was assessed before drink ingestion, at the end of the rest period, and at exhaustion. TYR ingestion had no effect on exercise capacity (PLA 61.4 ± 13.7 min, TYR 60.2 ± 15.4 min; p = .505). No differences in heart rate (p = .380), core temperature (p = .554), or weighted mean skin temperature (p = .167) were apparent between trials. Ingestion of TYR produced a marked increase in serum TYR concentrations (+236 ± 46 μmol/L; p < .001), with this difference maintained throughout exercise. No change was apparent during the PLA trial (p = .924). Exercise caused an increase in error rate during the complex component of the Stroop test (p = .034), but this response was not influenced by the drink ingested. No other component of cognitive function was altered by the protocol (all p > .05). Ingestion of a TYR solution did not influence time to exhaustion or several aspects of cognitive function when exercise was undertaken in a warm environment.
Devries, Michaela C; Hamadeh, Mazen J; Phillips, Stuart M; Tarnopolsky, Mark A
Numerous studies from our and other laboratories have shown that women have a lower respiratory exchange ratio (RER) during exercise than equally trained men, indicating a greater reliance on fat oxidation. Differences in estrogen concentration between men and women likely play a role in this sex difference. Differing estrogen and progesterone concentrations during the follicular (FP) and luteal (LP) phases of the female menstrual cycle suggest that fuel use may also vary between phases. The purpose of the current study was to determine the effect of menstrual cycle phase and sex upon glucose turnover and muscle glycogen utilization during endurance exercise. Healthy, recreationally active young women (n = 13) and men (n = 11) underwent a primed constant infusion of [6,6-2H]glucose with muscle biopsies taken before and after a 90-min cycling bout at 65% peak O2 consumption. LP women had lower glucose rate of appearance (Ra, P = 0.03), rate of disappearance (Rd, P = 0.03), and metabolic clearance rate (MCR, P = 0.04) at 90 min of exercise and lower proglycogen (P = 0.04), macroglycogen (P = 0.04), and total glycogen (P = 0.02) utilization during exercise compared with FP women. Men had a higher RER (P = 0.02), glucose Ra (P = 0.03), Rd (P = 0.03), and MCR (P = 0.01) during exercise compared with FP women, and men had a higher RER at 75 and 90 min of exercise (P = 0.04), glucose Ra (P = 0.01), Rd (P = 0.01), and MCR (P = 0.001) and a greater PG utilization (P = 0.05) compared with LP women. We conclude that sex, and to a lesser extent menstrual cycle, influence glucose turnover and glycogen utilization during moderate-intensity endurance exercise.
Silvennoinen, Mika; Ahtiainen, Juha P; Hulmi, Juha J; Pekkala, Satu; Taipale, Ritva S; Nindl, Bradley C; Laine, Tanja; Häkkinen, Keijo; Selänne, Harri; Kyröläinen, Heikki; Kainulainen, Heikki
The primary aim of the present study was to investigate the acute gene expression responses of PGC-1 isoforms and PGC-1α target genes related to mitochondrial biogenesis (cytochrome C), angiogenesis (VEGF-A), and muscle hypertrophy (myostatin), after a resistance or endurance exercise bout. In addition, the study aimed to elucidate whether the expression changes of studied transcripts were linked to phosphorylation of AMPK and MAPK p38. Nineteen physically active men were divided into resistance exercise (RE, n = 11) and endurance exercise (EE, n = 8) groups. RE group performed leg press exercise (10 × 10 RM, 50 min) and EE walked on a treadmill (∼80% HRmax, 50 min). Muscle biopsies were obtained from the vastus lateralis muscle before, 30 min, and 180 min after exercise. EE and RE significantly increased the gene expression of alternative promoter originated PGC-1α exon 1b- and 1bxs’-derived isoforms, whereas the proximal promoter originated exon 1a-derived transcripts were less inducible and were upregulated only after EE. Truncated PGC-1α transcripts were upregulated both after EE and RE. Neither RE nor EE affected the expression of PGC-1β. EE upregulated the expression of cytochrome C and VEGF-A, whereas RE upregulated VEGF-A and downregulated myostatin. Both EE and RE increased the levels of p-AMPK and p-MAPK p38, but these changes were not linked to the gene expression responses of PGC-1 isoforms. The present study comprehensively assayed PGC-1 transcripts in human skeletal muscle and showed exercise mode-specific responses thus improving the understanding of early signaling events in exercise-induced muscle adaptations. PMID:26438733
Van Proeyen, K; De Bock, K; Hespel, P
Nutrition is an important co-factor in exercise-induced training adaptations in muscle. We compared the effect of 6 weeks endurance training (3 days/week, 1-2 h at 75% VO(2peak)) in either the fasted state (F; n = 10) or in the high carbohydrate state (CHO, n = 10), on Ca(2+)-dependent intramyocellular signalling in young male volunteers. Subjects in CHO received a carbohydrate-rich breakfast before each training session, as well as ingested carbohydrates during exercise. Before (pretest) and after (posttest) the training period, subjects performed a 2 h constant-load exercise bout (~70% of pretest VO(2peak)) while ingesting carbohydrates (1 g/kg h(-1)). A muscle biopsy was taken from m. vastus lateralis immediately before and after the test, and after 4 h of recovery. Compared with pretest, in the posttest basal eukaryotic elongation factor 2 (eEF2) phosphorylation was elevated in CHO (P < 0.05), but not in F. In the pretest, exercise increased the degree of eEF2 phosphorylation about twofold (P < 0.05), and values returned to baseline within the 4 h recovery period in each group. However, in the posttest dephosphorylation of eEF2 was negated after recovery in CHO, but not in F. Independent of the dietary condition training enhanced the basal phosphorylation status of Phospholamban at Thr(17), 5'-AMP-activated protein kinase α (AMPKα), and Acetyl CoA carboxylase β (ACCβ), and abolished the exercise-induced increase of AMPKα and ACCβ (P < 0.05). In conclusion, training in the fasted state, compared with identical training with ample carbohydrate intake, facilitates post-exercise dephosphorylation of eEF2. This may contribute to rapid re-activation of muscle protein translation following endurance exercise.
Price, M J; Campbell, I G
The thermoregulatory responses of upper-body trained athletes were examined at rest, during prolonged arm crank exercise and recovery in cool (21.5 +/- 0.9 degrees C, 43.9 +/- 10.1% relative humidity; mean +/- s) and warm (31.5 +/- 0.6 degrees C, 48.9 +/- 8.4% relative humidity) conditions. Aural temperature increased from rest by 0.7 +/- 0.7 degrees C (P< 0.05) during exercise in cool conditions and by 1.6 +/- 0.7 degrees C during exercise in warm conditions (P< 0.05). During exercise in cool conditions, calf skin temperature decreased (1.5 +/- 1.3 degrees C), whereas an increase was observed during exercise in warm conditions (3.0 +/- 1.7 degrees C). Lower-body skin temperatures tended to increase by greater amounts than upper-body skin temperatures during exercise in warm conditions. No differences were observed in blood lactate, heart rate or respiratory exchange ratio responses between conditions. Perceived exertion at 45 min of exercise was greater than that reported at 5 min of exercise during the cool trial (P< 0.05), whereas during exercise in the warm trial the rating of perceived exertion increased from initial values by 30 min (P < 0.05). Heat storage, body mass losses and fluid consumption were greater during exercise in warm conditions (7.06 +/- 2.25 J x g(-1) x degrees C(-1), 1.3 +/- 0.5 kg and 1,038 +/- 356 ml, respectively) than in cool conditions (1.35 +/- 0.23 J x g(-1) x degrees C(-1), 0.8 +/- 0.2 kg and 530 +/- 284 ml, respectively; P < 0.05). The results of this study indicate that the increasing thermal strain with constant thermal stress in warm conditions is due to heat storage within the lower body. These results may aid in understanding thermoregulatory control mechanisms of populations with a thermoregulatory dysfunction, such as those with spinal cord injuries.
Ryushi, T.; Kita, Ichirou; Sakurai, Tomonobu; Yasumatsu, Mikinobu; Isokawa, Masanori; Aihara, Yasutugu; Hama, Kotaro
This study examined the effects of negative air ion exposure on the human cardiovascular and endocrine systems during rest and during the recovery period following moderate endurance exercise. Ten healthy adult men were studied in the presence (8,000-10,000 cm-3) or absence (200-400 cm-3) of negative air ions (25° C, 50% humidity) after 1 h of exercise. The level of exercise was adjusted to represent a 50-60% load compared with the subjects' maximal oxygen uptake, which was determined using a bicycle ergometer in an unmodified environment (22-23° C, 30-35% humidity, 200-400 negative air ions.cm-3). The diastolic blood pressure (DBP) values during the recovery period were significantly lower in the presence of negative ions than in their absence. The plasma levels of serotonin (5-HT) and dopamine (DA) were significantly lower in the presence of negative ions than in their absence. These results demonstrated that exposure to negative air ions produced a slow recovery of DBP and decreases in the levels of 5-HT and DA in the recovery period after moderate endurance exercise. 5-HT is thought to have contributed to the slow recovery of DBP.
Kapilevich, Leonid V; Zakharova, Anna N; Kabachkova, Anastasia V; Kironenko, Tatyana A; Orlov, Sergei N
Extensive exercise increases the plasma content of IL-6, IL-8, IL-15, leukemia inhibitory factor (LIF), and several other cytokines via their augmented transcription in skeletal muscle cells. However, the relative impact of aerobic and resistant training interventions on cytokine production remains poorly defined. In this study, we compared effects of dynamic and static load on cytokine plasma content in elite strength- and endurance-trained athletes vs. healthy untrained volunteers. The plasma cytokine content was measured before, immediately after, and 30 min post-exercise using enzyme-linked immunosorbent assay. Pedaling on a bicycle ergometer increased IL-6 and IL-8 content in the plasma of trained athletes by about 4- and 2-fold, respectively. In contrast to dynamic load, weightlifting had negligible impact on these parameters in strength exercise-trained athletes. Unlike IL-6 and IL-8, dynamic exercise had no impact on IL-15 and LIF, whereas static load increases the content of these cytokines by ~50%. Two-fold increment of IL-8 content seen in athletes subjected to dynamic exercise was absent in untrained individuals, whereas the ~50% increase in IL-15 triggered by static load in the plasma of weightlifting athletes was not registered in the control group. Thus, our results show the distinct impact of static and dynamic exercises on cytokine content in the plasma of trained athletes. They also demonstrate that both types of exercises differentially affect cytokine content in plasma of athletes and untrained persons.
Kapilevich, Leonid V.; Zakharova, Anna N.; Kabachkova, Anastasia V.; Kironenko, Tatyana A.; Orlov, Sergei N.
Extensive exercise increases the plasma content of IL-6, IL-8, IL-15, leukemia inhibitory factor (LIF), and several other cytokines via their augmented transcription in skeletal muscle cells. However, the relative impact of aerobic and resistant training interventions on cytokine production remains poorly defined. In this study, we compared effects of dynamic and static load on cytokine plasma content in elite strength- and endurance-trained athletes vs. healthy untrained volunteers. The plasma cytokine content was measured before, immediately after, and 30 min post-exercise using enzyme-linked immunosorbent assay. Pedaling on a bicycle ergometer increased IL-6 and IL-8 content in the plasma of trained athletes by about 4- and 2-fold, respectively. In contrast to dynamic load, weightlifting had negligible impact on these parameters in strength exercise-trained athletes. Unlike IL-6 and IL-8, dynamic exercise had no impact on IL-15 and LIF, whereas static load increases the content of these cytokines by ~50%. Two-fold increment of IL-8 content seen in athletes subjected to dynamic exercise was absent in untrained individuals, whereas the ~50% increase in IL-15 triggered by static load in the plasma of weightlifting athletes was not registered in the control group. Thus, our results show the distinct impact of static and dynamic exercises on cytokine content in the plasma of trained athletes. They also demonstrate that both types of exercises differentially affect cytokine content in plasma of athletes and untrained persons. PMID:28194116
Hayasaka, Miki; Tsunekawa, Haruka; Yoshinaga, Mariko; Murakami, Taro
Abstract Working muscle conserves adenosine triphosphate (ATP) for muscle contraction by attenuating protein synthesis through several different pathways. Regulated in development and DNA damage response 1 (REDD1) is one candidate protein that can itself attenuate muscle protein synthesis during muscle contraction. In this study, we investigated whether endurance exercise induces REDD1 expression in association with decreased mammalian target of rapamycin (mTOR) complex I (mTORC1) signaling and global protein synthesis in rat skeletal muscle. After overnight fasting, rats ran on a treadmill at a speed of 28 m/min for 60 min, and were killed before and immediately, 1, 3, 6, 12, and 24 h after exercise. REDD1 mRNA and corresponding protein levels increased rapidly immediately after exercise, and gradually decreased back to the basal level over a period of 6 h in the gastrocnemius muscle. Phosphorylation of mTOR Ser2448 and S6K1 Thr389 increased with the exercise, but diminished in 1–3 h into the recovery period after cessation of exercise. The rate of protein synthesis, as determined by the surface sensing of translation (SUnSET) method, was not altered by exercise in fasted muscle. These results suggest that REDD1 attenuates exercise‐induced mTORC1 signaling. This may be one mechanism responsible for blunting muscle protein synthesis during exercise and in the early postexercise recovery period. PMID:25539833
Hunter, Angus M; St Clair Gibson, Allan; Derman, Wayne E; Lambert, Michael; Dennis, Stephen C; Noakes, Timothy D
This study analysed the effect of selective beta(1)-blockade on neuromuscular recruitment characteristics during progressive endurance exercise. Ten healthy subjects ingested a selective beta(1)-blocker, acebutolol (200 mg b.d.), for 7 days (for one of two cycling trials), with a 10-day wash-out period between trials. On the last day of acebutolol ingestion subjects performed three successive 15-min rides at 30%, 50% and 70% of their peak power output and then cycled at increasing (15 W min(-1)) work rates to exhaustion. Force output, heart rate, submaximal VO(2), rate of perceived exertion (RPE), electromyographic (EMG) data and blood lactate were captured during the cycling activity. Peak work rate [270 (111) W vs 197 (75) W, CON vs BETA, P <0.01], time to exhaustion [49.7 (23.2) min vs 40.3 (23.7) min, CON vs BETA, P <0.05] and heart rate [mean, for the full ride 135.5 (38.3) beats min(-1) vs 111.5 (30.0) beats min(-1) CON vs BETA, P <0.05] were significantly lower for the group who ingested beta(1)-blockade (BETA) compared to the control group (CON). Although not significant, submaximal VO(2)was reduced in BETA during the ride, while RPE was significantly higher during the ride for BETA (P <0.01). Mean integrated electromyography was higher in the BETA group although these differences were not significant. Mean power frequency values of the BETA group showed a significant (P <0.05) shift to the upper end of the spectrum in comparison to the control group. Lactate values [11.7 (3.5) mmol x l(-1) vs 7.1 (4.1) mmol x l(-1)CON vs BETA] were significantly lower (P <0.05) at exhaustion in BETA. Significant reductions in cycling performance were found when subjects ingested beta(1)-blockers. This study has shown significant shifts to the upper end of the EMG frequency spectrum after beta(1)-blocker ingestion, which could be caused by a change in neuromuscular recruitment strategy to compensate for the impaired submaximal exercise performance.
Ramírez-Campillo, Rodrigo; Vergara-Pedreros, Marcelo; Henríquez-Olguín, Carlos; Martínez-Salazar, Cristian; Alvarez, Cristian; Nakamura, Fábio Yuzo; De La Fuente, Carlos I; Caniuqueo, Alexis; Alonso-Martinez, Alicia M; Izquierdo, Mikel
In a randomised controlled trial design, effects of 6 weeks of plyometric training on maximal-intensity exercise and endurance performance were compared in male and female soccer players. Young (age 21.1 ± 2.7 years) players with similar training load and competitive background were assigned to training (women, n = 19; men, n = 21) and control (women, n = 19; men, n = 21) groups. Players were evaluated for lower- and upper-body maximal-intensity exercise, 30 m sprint, change of direction speed and endurance performance before and after 6 weeks of training. After intervention, the control groups did not change, whereas both training groups improved jumps (effect size (ES) = 0.35-1.76), throwing (ES = 0.62-0.78), sprint (ES = 0.86-1.44), change of direction speed (ES = 0.46-0.85) and endurance performance (ES = 0.42-0.62). There were no differences in performance improvements between the plyometric training groups. Both plyometric groups improved more in all performance tests than the controls. The results suggest that adaptations to plyometric training do not differ between men and women.
Lavorato, Victor Neiva; Del Carlo, Ricardo Junqueira; da Cunha, Daise Nunes Queiroz; Okano, Barbara Silva; Belfort, Felipe Gomes; de Freitas, Juliana Silveira; da Mota, Gloria de Fatima Alves; Quintão-Júnior, Judson Fonseca; Silame-Gomes, Luis Henrique Lobo; Drummond, Filipe Rios; Carneiro-Júnior, Miguel Araújo; de Oliveira, Edilamar Menezes; Monteiro, Betania Souza; Prímola-Gomes, Thales Nicolau; Natali, Antônio José
We tested the effects of early mesenchymal stem cell (MSC) therapy associated with endurance exercise on the structural and functional cardiac remodeling of rats with myocardial infarctation (MI). Male Wistar rats (40 days old) were divided into 6 groups: control and exercise sham; control and exercise MI; and control and exercise MI MSC. MI was surgically induced and bone marrow-derived MSCs were immediately injected via caudal vein (concentration: 1 × 10(6 )cells). Twenty-four hours later ET groups exercised on a treadmill (5 days/week; 60 min/day; 60% of maximal running velocity) for 12 weeks. Structural and functional changes were determined by echocardiography. Contractility and intracellular global calcium ([Ca(2 +)]i) transient were measured in myocytes from the left ventricular (LV) non-infarcted area. Calcium regulatory proteins were measured by Western blot. MI increased (p < 0.05) heart, ventricular and LV weights and its ratios to body weight; LV internal dimension in diastole (LVID-D) and in systole (LVID-S) and LV free wall in diastole (LVFW-D), but reduced the thickness of interventricular septum in systole (IVS-S), ejection fraction (EF) and fractional shortening (FS). MI augmented (p < 0.05) the times to peak and to half relaxation of cell shortening as well as the amplitude of the [Ca(2 +)]i transient and the times to peak and to half decay. Early MSCs therapy restored LVFW-D, IVS-S and the amplitude and time to half decay of the [Ca(2 +)]i transient. Early endurance exercise intervention increased (p < 0.05) LVFW-S, IVS-S, EF and FS, and reduced the times to peak and to half relaxation of cell shortening, and the amplitude of the [Ca(2 +)]i transient. Exercise training also increased the expression of left ventricular SERCA2a and PLBser16. Nevertheless, the combination of these therapies did not cause additive effects. In conclusion, combining early MSCs therapy and endurance exercise does not potentiate the benefits of such treatments to
Margolis, Lee M.; McClung, Holly L.; Murphy, Nancy E.; Carrigan, Christopher T.; Pasiakos, Stefan M.
Skeletal muscle microRNAs (myomiR) expression is modulated by exercise, however, the influence of endurance exercise mode, combined with essential amino acid and carbohydrate (EAA+CHO) supplementation are not well defined. This study determined the effects of weighted versus non-weighted endurance exercise, with or without EAA+CHO ingestion on myomiR expression and their association with muscle protein synthesis (MPS). Twenty five adults performed 90 min of metabolically-matched (2.2 VO2 L·m−1) load carriage (LC; performed on a treadmill wearing a vest equal to 30% of individual body mass) or cycle ergometry (CE) exercise, during which EAA+CHO (10 g EAA and 46 g CHO) or non-nutritive control (CON) drinks were consumed. Expression of myomiR (RT-qPCR) were determined at rest (PRE), immediately post-exercise (POST), and 3 h into recovery (REC). Muscle protein synthesis (2H5-phenylalanine) was measured during exercise and recovery. Relative to PRE, POST, and REC expression of miR-1-3p, miR-206, miR-208a-5, and miR-499 was lower (P < 0.05) for LC compared to CE, regardless of dietary treatment. Independent of exercise mode, miR-1-3p and miR-208a-5p expression were lower (P < 0.05) after ingesting EAA+CHO compared to CON. Expression of miR-206 was highest for CE-CON than any other treatment (exercise-by-drink, P < 0.05). Common targets of differing myomiR were identified as markers within mTORC1 signaling, and miR-206 and miR-499 were inversely associated with MPS rates immediately post-exercise. These findings suggest the alterations in myomiR expression between exercise mode and EAA+CHO intake may in part be due to differing MPS modulation immediately post-exercise. PMID:28386239
Abdallah, Sara J; Krug, Robin; Jensen, Dennis
This randomized, double-blind, crossover study examined the effects of a clothing ensemble made of a synthetic fabric promoted as having superior cooling properties (COOL) on exercise performance and its physiological and perceptual determinants during cycle exercise in ambient laboratory conditions that mimic environmental conditions of indoor training/sporting facilities. Twenty athletes (15 men:5 women) aged 25.8 ± 1.2 years (mean ± SEM) with a maximal rate of O2 consumption of 63.7 ± 1.5 mL·kg−1·min−1 completed cycle exercise testing at 85% of their maximal incremental power output to exhaustion while wearing an ensemble consisting of a fitted long-sleeved shirt and full trousers made of either COOL or a synthetic control fabric (CTRL). Exercise endurance time was not different under COOL versus CTRL conditions: 12.38 ± 0.98 versus 11.75 ± 1.10 min, respectively (P > 0.05). Similarly, COOL had no effect on detailed thermoregulatory (skin and esophageal temperatures), cardiometabolic, ventilatory, and perceptual responses to exercise (all P > 0.05). In conclusion, clothing made of a synthetic fabric with purported “cooling” properties did not improve high-intensity cycle exercise endurance in trained athletes under ambient laboratory conditions that mimic the environmental conditions of indoor training/sporting facilities. PMID:26290527
Hamadeh, Mazen J; Devries, Michaela C; Tarnopolsky, Mark A
Healthy active men exhibit higher rates of carbohydrate (CHO) and leucine oxidation and lower rates of lipid oxidation compared with their female counterparts both at rest and during moderate intensity endurance exercise. We postulated that this reduced dependence on amino acids as a fuel source in women was due to the female sex hormone estrogen. In a randomized, double-blind, placebo-controlled, cross-over design, we investigated the effect of supplementing 12 recreationally active men with estrogen on whole body substrate oxidation and leucine kinetics at rest and during moderate intensity endurance exercise. Subjects cycled for 90 min at an intensity of 65% maximum O(2) consumption after 8 d of either estrogen supplementation (2 mg 17beta-estradiol/d) or placebo (polycose). After a 2-wk washout period, they repeated the test after 8 d of the alternate treatment. On the test day, after a primed continuous infusion of l-[(13)C]leucine, O(2) consumption, CO(2) production, steady-state breath (13)CO(2), and plasma alpha-[(13)C]ketoisocaproate enrichments were measured at rest and at 60, 75, and 90 min during exercise in the postabsorptive state. Exercise increased energy expenditure more than 5-fold, CHO oxidation more than 6-fold, lipid oxidation more than 4-fold, and leucine oxidation 2.2-fold (all P < 0.0001), whereas it decreased the ratio of lipid to CHO oxidation by 50-70% (P = 0.003) compared with values at rest. Estrogen supplementation decreased respiratory exchange ratio during exercise (P = 0.03). Estrogen supplementation significantly decreased CHO oxidation by 5-16% (P = 0.04) and leucine oxidation by 16% (P = 0.01), whereas it significantly increased lipid oxidation by 22-44% (P = 0.024) at rest and during exercise. We conclude that estrogen influences fuel source selection at rest and during endurance exercise in recreationally active men, characterized by a reduced dependence on amino acids and CHO and an increased reliance on lipids as a fuel
Cheng, I-Shiung; Wang, Yi-Wen; Chen, I-Fan; Hsu, Gi-Sheng; Hsueh, Chun-Fang; Chang, Chen-Kang
The central nervous system plays a crucial role in fatigue during endurance exercise. Branched-chain amino acids (BCAA) could reduce cerebral serotonin synthesis by competing with its precursor tryptophan for crossing the blood brain barrier. Arginine and citrulline could prevent excess hyperammonemia accompanied by BCAA supplementation. This study investigated the combination of BCAA, arginine, and citrulline on endurance performance in two consecutive days. Seven male and three female endurance runners ingested 0.17 g·kg-1 BCAA, 0.05 g·kg-1 arginine and 0.05 g·kg-1 citrulline (AA trial) or placebo (PL trial) in a randomized cross-over design. Each trial contained a 5000 m time trial on the first day, and a 10000 m time trial on the second day. The AA trial had significantly better performance in 5000 m (AA: 1065.7 ± 33.9 s; PL: 1100.5 ± 40.4 s) and 10000 m (AA: 2292.0 ± 211.3 s; PL: 2375.6 ± 244.2 s). The two trials reported similar ratings of perceived exertion. After exercise, the AA trial had significantly lower tryptophan/BCAA ratio, similar NH3, and significantly higher urea concentrations. In conclusion, the supplementation could enhance time-trial performance in two consecutive days in endurance runners, possibly through the inhibition of cerebral serotonin synthesis by BCAA and the prevention of excess hyperammonemia by increased urea genesis. Key points The combined supplementation of BCAA, arginine, and citrulline could enhance performance in 5000 m and 10000 m in 2 consecutive days in competitive runners. The supplementation may be helpful in multi-day competitions. The supplemented BCAA may alleviate central fatigue, allowing the subjects to run faster at the same degree of perceived exertion. The hyperammonemia that is usually accompanied with BCAA supplementation may be prevented by arginine and citrulline through increased urea genesis. PMID:27803630
Rodríguez-Bies, Elizabeth; Santa-Cruz Calvo, Sara; Fontán-Lozano, Angela; Peña Amaro, José; Berral de la Rosa, Francisco J; Carrión, Angel M; Navas, Plácido; López-Lluch, Guillermo
Every other day feeding (EOD) and exercise induce changes in cell metabolism. The aim of the present work was to know if both EOD and exercise produce similar effects on physical capacity, studying their physiological, biochemical and metabolic effects on muscle. Male OF-1 mice were fed either ad libitum (AL) or under EOD. After 18 weeks under EOD, animals were also trained by using a treadmill for another 6 weeks and then analyzed for physical activity. Both, EOD and endurance exercise increased the resistance of animals to extenuating activity and improved motor coordination. Among the groups that showed the highest performance, AL and EOD trained animals, ALT and EODT respectively, only the EODT group was able to increase glucose and triglycerides levels in plasma after extenuating exercise. No high effects on mitochondrial respiratory chain activities or protein levels neither on coenzyme Q levels were found in gastrocnemius muscle. However, exercise and EOD did increase β-oxidation activity in this muscle accompanied by increased CD36 levels in animals fed under EOD and by changes in shape and localization of mitochondria in muscle fibers. Furthermore, EOD and training decreased muscle damage after strenuous exercise. EOD also reduced the levels of lipid peroxidation in muscle. Our results indicate that EOD improves muscle performance and resistance by increasing lipid catabolism in muscle mitochondria at the same time that prevents lipid peroxidation and muscle damage.
Rodríguez-Bies, Elizabeth; Santa-Cruz Calvo, Sara; Fontán-Lozano, Ángela; Peña Amaro, José; Berral de la Rosa, Francisco J.; Carrión, Ángel M.; Navas, Plácido; López-Lluch, Guillermo
Every other day feeding (EOD) and exercise induce changes in cell metabolism. The aim of the present work was to know if both EOD and exercise produce similar effects on physical capacity, studying their physiological, biochemical and metabolic effects on muscle. Male OF-1 mice were fed either ad libitum (AL) or under EOD. After 18 weeks under EOD, animals were also trained by using a treadmill for another 6 weeks and then analyzed for physical activity. Both, EOD and endurance exercise increased the resistance of animals to extenuating activity and improved motor coordination. Among the groups that showed the highest performance, AL and EOD trained animals, ALT and EODT respectively, only the EODT group was able to increase glucose and triglycerides levels in plasma after extenuating exercise. No high effects on mitochondrial respiratory chain activities or protein levels neither on coenzyme Q levels were found in gastrocnemius muscle. However, exercise and EOD did increase β-oxidation activity in this muscle accompanied by increased CD36 levels in animals fed under EOD and by changes in shape and localization of mitochondria in muscle fibers. Furthermore, EOD and training decreased muscle damage after strenuous exercise. EOD also reduced the levels of lipid peroxidation in muscle. Our results indicate that EOD improves muscle performance and resistance by increasing lipid catabolism in muscle mitochondria at the same time that prevents lipid peroxidation and muscle damage. PMID:21085477
Kato, Hiroyuki; Suzuki, Katsuya; Bannai, Makoto; Moore, Daniel R.
A higher protein intake has been recommended for endurance athletes compared with healthy non-exercising individuals based primarily on nitrogen balance methodology. The aim of this study was to determine the estimated average protein requirement and recommended protein intake in endurance athletes during an acute 3-d controlled training period using the indicator amino acid oxidation method. After 2-d of controlled diet (1.4 g protein/kg/d) and training (10 and 5km/d, respectively), six male endurance-trained adults (28±4 y of age; Body weight, 64.5±10.0 kg; VO2peak, 60.3±6.7 ml·kg-1·min-1; means±SD) performed an acute bout of endurance exercise (20 km treadmill run) prior to consuming test diets providing variable amounts of protein (0.2–2.8 g·kg-1·d-1) and sufficient energy. Protein was provided as a crystalline amino acid mixture based on the composition of egg protein with [1-13C]phenylalanine provided to determine whole body phenylalanine flux, 13CO2 excretion, and phenylalanine oxidation. The estimated average protein requirement was determined as the breakpoint after biphasic linear regression analysis with a recommended protein intake defined as the upper 95% confidence interval. Phenylalanine flux (68.8±8.5 μmol·kg-1·h-1) was not affected by protein intake. 13CO2 excretion displayed a robust bi-phase linear relationship (R2 = 0.86) that resulted in an estimated average requirement and a recommended protein intake of 1.65 and 1.83 g protein·kg-1·d-1, respectively, which was similar to values based on phenylalanine oxidation (1.53 and 1.70 g·kg-1·d-1, respectively). We report a recommended protein intake that is greater than the RDA (0.8 g·kg-1·d-1) and current recommendations for endurance athletes (1.2–1.4 g·kg-1·d-1). Our results suggest that the metabolic demand for protein in endurance-trained adults on a higher volume training day is greater than their sedentary peers and current recommendations for athletes based primarily on
Quirion, A.; Boisvert, P.; Brisson, G. R.; Decarufel, D.; Laurencelle, L.; Dulac, S.; Vogelaere, P.; Therminarias, A.
Physiological and metabolic output responses to facial cooling during a graded maximal exercise and a prolonged submaximal exercise lasting 30 min at 65%dot VO_2 max were investigated in five male subjects. Pedalling on a cycle ergometer was performed both with and without facial cooling (10°C, 4.6 m s-1). Facial cooling at the end of graded maximal exercise apparently had no effect on plasma lactate (LA), maximal oxygen consumption (dot VO_2 max), maximal heart rate (HR max), rectal temperature ( T re), work-load, lactate threshold (LT), ventilatory threshold (VT) and onset of blood lactate accumulation (OBLA). However, the response to facial cooling after prolonged submaximal exercise is significantly different for heart rate and work-load. The results suggest that facial wind stimulation during maximal exercise does not produce a stress high enough to alter the metabolic and physiological responses.
Jeukendrup, Asker E; Raben, Anne; Gijsen, Annemie; Stegen, Jos H C H; Brouns, Fred; Saris, Wim H M; Wagenmakers, Anton J M
The objectives of this study were (1) to investigate whether glucose ingestion during prolonged exercise reduces whole body muscle glycogen oxidation, (2) to determine the extent to which glucose disappearing from the plasma is oxidized during exercise with and without carbohydrate ingestion and (3) to obtain an estimate of gluconeogenesis. After an overnight fast, six well-trained cyclists exercised on three occasions for 120 min on a bicycle ergometer at 50% maximum velocity of O2 uptake and ingested either water (Fast), or a 4% glucose solution (Lo-Glu) or a 22% glucose solution (Hi-Glu) during exercise. Dual tracer infusion of [U-13C]-glucose and [6,6-2H2]-glucose was given to measure the rate of appearance (Ra) of glucose, muscle glycogen oxidation, glucose carbon recycling, metabolic clearance rate (MCR) and non-oxidative disposal of glucose. Glucose ingestion markedly increased total Ra especially with Hi-Glu. After 120 min Ra and rate of disappearance (Rd) of glucose were 51-52 μmol kg−1 min−1 during Fast, 73-74 μmol kg−1 min−1 during Lo-Glu and 117–119 μmol kg−1 min−1 during Hi-Glu. The percentage of Rd oxidized was between 96 and 100% in all trials. Glycogen oxidation during exercise was not reduced by glucose ingestion. The vast majority of glucose disappearing from the plasma is oxidized and MCR increased markedly with glucose ingestion. Glucose carbon recycling was minimal suggesting that gluconeogenesis in these conditions is negligible. PMID:10050023
Peres, Sidney B; de Moraes, Solange M Franzói; Costa, Cecilia E M; Brito, Luciana C; Takada, Julie; Andreotti, Sandra; Machado, Magaly A; Alonso-Vale, Maria Isabel C; Borges-Silva, Cristina N; Lima, Fabio B
Endurance exercise training promotes important metabolic adaptations, and the adipose tissue is particularly affected. The aim of this study was to investigate how endurance exercise training modulates some aspects of insulin action in isolated adipocytes and in intact adipose tissue. Male Wistar rats were submitted to daily treadmill running (1 h/day) for 7 wk. Sedentary age-matched rats were used as controls. Final body weight, body weight gain, and epididymal fat pad weight did not show any statistical differences between groups. Adipocytes from trained rats were smaller than those from sedentary rats (205 +/- 16.8 vs. 286 +/- 26.4 pl; P < 0.05). Trained rats showed decreased plasma glucose (4.9 +/- 0.13 vs. 5.3 +/- 0.07 mM; P < 0.05) and insulin levels (0.24 +/- 0.012 vs. 0.41 +/- 0.049 mM; P < 0.05) and increased insulin-stimulated glucose uptake (23.1 +/- 3.1 vs. 12.1 +/- 2.9 pmol/cm(2); P < 0.05) compared with sedentary rats. The number of insulin receptors and the insulin-induced tyrosine phosphorylation of insulin receptor-beta subunit did not change between groups. Insulin-induced tyrosine phosphorylation insulin receptor substrates (IRS)-1 and -2 increased significantly (1.57- and 2.38-fold, respectively) in trained rats. Insulin-induced IRS-1/phosphatidylinositol 3 (PI3)-kinase (but not IRS-2/PI3-kinase) association and serine Akt phosphorylation also increased (2.06- and 3.15-fold, respectively) after training. The protein content of insulin receptor-beta subunit, IRS-1 and -2, did not differ between groups. Taken together, these data support the hypothesis that the increased adipocyte responsiveness to insulin observed after endurance exercise training is modulated by IRS/PI3-kinase/Akt pathway.
Zouhal, H; Gratas-Delamarche, A; Rannou, F; Granier, P; Bentue-Ferrer, D; Delamarche, P
The purpose of this study was to determine the effect of aging and training on the adrenaline (A) and noradrenaline (NA) responses during the Wingate-test in three age groups of subjects: 21 year old untrained subjects (21U), 21 year old endurance trained (21T) (national elite runners), 34 year old endurance trained (34T) (national elite runners). Performances during the test were judged using the usual parameters of peak power (Wmax) and mean power (W) expressed in absolute or relative values. A and NA responses were measured at rest (A0 and NA0) immediately at the end of the exercise (Amax and NAmax) and after 5 minutes recovery (A5 and NA5). Plasma maximal lactate (La(max)) was determined 3 minutes after the end of the exercise. Wmax, W and La(max) were always significantly lower in 34T compared to 21T and 21U. The catecholamine responses were similar in 21T and 21U. Inversely, a significantly lower value of Amax was observed in 34T (2.01 +/- 0.5 nmol x l(-1)) compared to 21U (3.62 +/- 0.3 nmol x l(-1)) associated with a significantly higher value of NA(max) in 34T versus 21T and 21U. Thus, the Amax/NA(max) ratio was found to be significantly lower in the older subjects versus both 21T and 21U. All these findings indicated that endurance training did not affect the sympathoadrenergic responses to a supramaximal exercise and suggested that only one decade may reduce the capacity of the medulla to secrete adrenaline and therefore the adrenal medulla responsiveness to the sympathetic nervous activity.
Lane, A R; O'Leary, C B; Hackney, A C
Research has shown that total testosterone (tT) levels in women increase acutely during a prolonged bout of aerobic exercise. Few studies, however, have considered the impact of the menstrual cycle phase on this response or have looked at the biologically active free testosterone (fT) form responses. Therefore, this study examined the fT concentration response independently and as a percentage (fT%) of tT to prolonged aerobic exercise during phases of the menstrual cycle with low estrogen-progesterone (L-EP; i.e., follicular phase) and high estrogen-progesterone (H-EP; i.e., luteal phase). Ten healthy, recreationally trained, eumennorrheic women (X ± SD: age = 20 ± 2 y, mass = 58.7 ± 8.3 kg, body fat = 22.3 ± 4.9 %, VO(2max) = 50.7 ± 9.0 ml/kg/min) participated in a laboratory based study and completed a 60-minute treadmill run during the L-EP and H-EP menstrual phases at ~70% of VO(2max). Blood was drawn prior to (PRE), immediately after (POST) and following 30 minutes of recovery (30POST) with each 60-minute run. During H-EP, there was a significant increase in fT concentrations from PRE to POST (p < 0.01) while in L-EP fT levels were unchanged; which resulted in fT being significantly higher at H-EP POST versus L-EP POST (p < 0.03). Area-under-the-curve (AUC) responses were calculated, for fT the total AUC was greater in H-EP than L-EP (p < 0.04). There was no significant interaction of fT% between phases and exercise sampling time. There was, however, a main effect for exercise where fT% POST was a greater proportion of tT than at PRE (p < 0.01). In summary, hormonal changes associated with the menstrual cycle impact fT response to a prolonged aerobic exercise bout; specifically, there being higher levels under H-EP conditions. This suggests more biologically active T is available during exercise in this phase. This response may be a function of the higher core temperatures found with H-EP causing greater sex hormone binding protein release of T, or could
Tsuji, Bun; Honda, Yasushi; Fujii, Naoto; Kondo, Narihiko; Nishiyasu, Takeshi
We investigated whether a core temperature threshold for hyperthermic hyperventilation is seen during prolonged submaximal exercise in the heat when core temperature before the exercise is reduced and whether the evoked hyperventilatory response is affected by altering the initial core temperature. Ten male subjects performed three exercise trials at 50% of peak oxygen uptake in the heat (37°C and 50% relative humidity) after altering their initial esophageal temperature (T(es)). Initial T(es) was manipulated by immersion for 25 min in water at 18°C (Precooling), 35°C (Control), or 40°C (Preheating). T(es) after the water immersion was significantly higher in the Preheating trial (37.5 ± 0.3°C) and lower in the Precooling trial (36.1 ± 0.3°C) than in the Control trial (36.9 ± 0.3°C). In the Precooling trial, minute ventilation (Ve) showed little change until T(es) reached 37.1 ± 0.4°C. Above this core temperature threshold, Ve increased linearly in proportion to increasing T(es). In the Control trial, Ve increased as T(es) increased from 37.0°C to 38.6°C after the onset of exercise. In the Preheating trial, Ve increased from the initially elevated levels of T(es) (from 37.6 to 38.6°C) and Ve. The sensitivity of Ve to increasing T(es) above the threshold for hyperventilation (the slope of the T(es)-Ve relation) did not significantly vary across trials (Precooling trial = 10.6 ± 5.9, Control trial = 8.7 ± 5.1, and Preheating trial = 9.2 ± 6.9 L·min(-1)·°C(-1)). These results suggest that during prolonged submaximal exercise at a constant workload in humans, there is a clear core temperature threshold for hyperthermic hyperventilation and that the evoked hyperventilatory response is unaffected by altering initial core temperature.
Allsen, Philip E.
Cardiovascular endurance is defined as the ability of the heart, lungs, and circulatory system to provide the cells of the body with the necessary substances to perform work for extended periods of time. People beginning such a program need to have an understanding of warming-up, intensity, duration, and frequency of an exercise program. (JN)
Spence, Angela L; Naylor, Louise H; Carter, Howard H; Buck, Christopher L; Dembo, Lawrence; Murray, Conor P; Watson, Philip; Oxborough, David; George, Keith P; Green, Daniel J
The principle that 'concentric' cardiac hypertrophy occurs in response to strength training, whilst 'eccentric' hypertrophy results from endurance exercise has been a fundamental tenet of exercise science. This notion is largely based on cross-sectional comparisons of athletes using echocardiography. In this study, young (27.4 ± 1.1 years) untrained subjects were randomly assigned to supervised, intensive, endurance (END, n = 10) or resistance (RES, n = 13) exercise and cardiac MRI scans and myocardial speckle tracking echocardiography were performed at baseline, after 6 months of training and after a subsequent 6 weeks of detraining. Aerobic fitness increased significantly in END (3.5 to 3.8 l min(-1), P < 0.05) but was unchanged in RES. Muscular strength significantly improved compared to baseline in both RES and END ( = 53.0 ± 1.1 versus 36.4 ± 4.5 kg, both P < 0.001) as did lean body mass (2.3 ± 0.4 kg, P < 0.001 versus 1.4 ± 0.6 kg P < 0.05). MRI derived left ventricular (LV) mass increased significantly following END (112.5 ± 7.3 to 121.8 ± 6.6 g, P < 0.01) but not RES, whilst training increased end-diastolic volume (LVEDV, END: +9.0 ± 5.0 versus RES +3.1 ± 3.6 ml, P = 0.05). Interventricular wall thickness significantly increased with training in END (1.06 ± 0.0 to 1.14 ± 0.06, P < 0.05) but not RES. Longitudinal strain and strain rates did not change following exercise training. Detraining reduced aerobic fitness, LV mass and wall thickness in END (P < 0.05), whereas LVEDV remained elevated. This study is the first to use MRI to compare LV adaptation in response to intensive supervised endurance and resistance training. Our findings provide some support for the 'Morganroth hypothesis', as it pertains to LV remodelling in response to endurance training, but cast some doubt over the proposal that remodelling occurs in response to resistance training.
Hostrup, Morten; Bangsbo, Jens
Mechanisms underlying fatigue development and limitations for performance during intense exercise have been intensively studied during the past couple of decades. Fatigue development may involve several interacting factors and depends on type of exercise undertaken and training level of the individual. Intense exercise (½-6 min) causes major ionic perturbations (Ca(2+) , Cl(-) , H(+) , K(+) , lactate(-) and Na(+) ) that may reduce sarcolemmal excitability, Ca(2+) release and force production of skeletal muscle. Maintenance of ion homeostasis is thus essential to sustain force production and power output during intense exercise. Regular speed endurance training (SET), i.e. exercise performed at intensities above that corresponding to maximum oxygen consumption (V̇O2, max ), enhances intense exercise performance. However, most of the studies that have provided mechanistic insight into the beneficial effects of SET have been conducted in untrained and recreationally active individuals, making extrapolation towards athletes' performance difficult. Nevertheless, recent studies indicate that only a few weeks of SET enhances intense exercise performance in highly trained individuals. In these studies, the enhanced performance was not associated with changes in V̇O2, max and muscle oxidative capacity, but rather with adaptations in muscle ion handling, including lowered interstitial concentrations of K(+) during and in recovery from intense exercise, improved lactate(-) -H(+) transport and H(+) regulation, and enhanced Ca(2+) release function. The purpose of this Topical Review is to provide an overview of the effect of SET and to discuss potential mechanisms underlying enhancements in performance induced by SET in already well-trained individuals with special emphasis on ion handling in skeletal muscle.
There is a growing population of veteran endurance athletes, regularly participating in training and competition. Although the graded benefit of exercise on cardiovascular health and mortality is well established, recent studies have raised concern that prolonged and strenuous endurance exercise may predispose to atrial and ventricular arrhythmias. Atrial fibrillation (AF) and atrial flutter are facilitated by atrial remodelling, atrial ectopy, and an imbalance of the autonomic nervous system. Endurance sports practice has an impact on all of these factors and may therefore act as a promoter of these arrhythmias. In an animal model, long-term intensive exercise training induced fibrosis in both atria and increased susceptibility to AF. While the prevalence of AF is low in young competitive athletes, it increases substantially in the aging athlete, which is possibly associated with an accumulation of lifetime training hours and participation in competitions. A recent meta-analysis revealed a 5-fold increased risk of AF in middle-aged endurance athletes with a striking male predominance. Beside physical activity, height and absolute left atrial size are independent risk factors for lone AF and the stature of men per se may explain part of their higher risk of AF. Furthermore, for a comparable amount of training volume and performance, male non-elite athletes exhibit a higher blood pressure at rest and peak exercise, a more concentric type of left ventricular remodelling, and an altered diastolic function, possibly contributing to a more pronounced atrial remodelling. The sports cardiologist should be aware of the distinctive features of AF in athletes. Therapeutic recommendations should be given in close cooperation with an electrophysiologist. Reduction of training volume is often not desired and drug therapy not well tolerated. An early ablation strategy may be appropriate for some athletes with an impaired physical performance, especially when continuation of
Hakim, Renée M.; Ross, Michael D.; Runco, Wendy; Kane, Michael T.
The purpose of this study was to investigate the impact of a community-based aquatic exercise program on physical performance among adults with mild to moderate intellectual disability (ID). Twenty-two community-dwelling adults with mild to moderate ID volunteered to participate in this study. Participants completed an 8-week aquatic exercise program (2 days/wk, 1 hr/session). Measures of physical performance, which were assessed prior to and following the completion of the aquatic exercise program, included the timed-up-and-go test, 6-min walk test, 30-sec chair stand test, 10-m timed walk test, hand grip strength, and the static plank test. When comparing participants’ measures of physical performance prior to and following the 8-week aquatic exercise program, improvements were seen in all measures, but the change in scores for the 6-min walk test, 30-sec chair stand test, and the static plank test achieved statistical significance (P<0.05). An 8-week group aquatic exercise program for adults with ID may promote improvements in endurance and balance/mobility. PMID:28349039
Zamanian, Mohammad; Hajizadeh, Mohammad R; Nadimi, Ali Esmaeili; Shamsizadeh, Ali; Allahtavakoli, Mohammad
The aim of this study was to investigate effects of troxerutin (TRX) on endurance capacity, oxidative stress and MMP-9 levels in trained male rats. Forty male Wistar rats were divided into five groups. The control (Vehicle) and exercise training (5 days/week) with vehicle treatment (Exercise), exercise training with TRX treatment at 75 (Ex-TRX75), 150 (Ex-TRX150), and 300 mg/kg (Ex-TRX300). The treated groups received TRX by gavage every day while the other groups received water for 30 days. On the 30(th) day, rats were sacrificed immediately after exhaustive swimming test, and some biochemical parameters were measured. Exhaustion swimming time in the Ex-TRX75, Ex-TRX150 and Ex-TRX300 groups significantly increased 1.2, 1.93 and 2.1-fold compared to the Vehicle group, respectively. TRX significantly increased glucose level (P ˂ 0.05) and reduced CK activity (P ˂ 0.001) compared to the Vehicle and exercise groups. TRX300 significantly reduced ALP and LDH activities (P ˂ 0.05) and BUN (P ˂ 0.05) and MMP-9 levels (P ˂ 0.05) compared to the Vehicle and Exercise groups. Additionally, TRX300 and TRX150 significantly increased SOD activity compared to the Vehicle group (P ˂ 0.05). Our results provide experimental evidence in supporting clinical use of TRX as an effective agent against fatigue. This article is protected by copyright. All rights reserved.
Trangmar, Steven J; Chiesa, Scott T; Llodio, Iñaki; Garcia, Benjamin; Kalsi, Kameljit K; Secher, Niels H; González-Alonso, José
Dehydration hastens the decline in cerebral blood flow (CBF) during incremental exercise, whereas the cerebral metabolic rate for O2 (CMRO2 ) is preserved. It remains unknown whether CMRO2 is also maintained during prolonged exercise in the heat and whether an eventual decline in CBF is coupled to fatigue. Two studies were undertaken. In study 1, 10 male cyclists cycled in the heat for ∼2 h with (control) and without fluid replacement (dehydration) while internal and external carotid artery blood flow and core and blood temperature were obtained. Arterial and internal jugular venous blood samples were assessed with dehydration to evaluate CMRO2 . In study 2, in 8 male subjects, middle cerebral artery blood velocity was measured during prolonged exercise to exhaustion in both dehydrated and euhydrated states. After a rise at the onset of exercise, internal carotid artery flow declined to baseline with progressive dehydration (P < 0.05). However, cerebral metabolism remained stable through enhanced O2 and glucose extraction (P < 0.05). External carotid artery flow increased for 1 h but declined before exhaustion. Fluid ingestion maintained cerebral and extracranial perfusion throughout nonfatiguing exercise. During exhaustive exercise, however, euhydration delayed but did not prevent the decline in cerebral perfusion. In conclusion, during prolonged exercise in the heat, dehydration accelerates the decline in CBF without affecting CMRO2 and also restricts extracranial perfusion. Thus, fatigue is related to a reduction in CBF and extracranial perfusion rather than CMRO2 .
Li, Tzai-Li; Gleeson, Michael
ingestion during the first or second bout of exercise, but not during the recovery interval, is likely to better maintain plasma glucose concentrations and attenuate the responses of plasma stress hormones to a second exercise bout than ingestion of fluid alone. Two bouts of 90 min cycling at 60% VO2max on the same day appears to inhibit saliva flow rate during the second exercise bout but does not alter sIgA transcytosis. Our results show that carbohydrate ingestion during any period of two prolonged exercise bouts does not induce different effects on oral immunity compared with placebo.
Kuitunen, S; Avela, J; Kyröläinen, H; Nicol, C; Komi, P V
The purpose of the present study was to examine the acute and long-term fatigue effects of exhausting stretch-shortening cycle (SSC) exercise on the stiffness of ankle and knee joints. Five subjects were fatigued on a sledge apparatus by 100 maximal rebound jumps followed by continuous submaximal jumping until complete exhaustion. Neuromuscular fatigue effects were examined in submaximal hopping (HOP) and in maximal drop jumps (DJ) from 35 (DJ35) and 55 cm (DJ55) heights on a force plate. Additional force and reflex measurements were made using an ankle ergometer. Jumping tests and ankle ergometer tests were carried out before, immediately after, 2 h (2H), 2 days and 7 days (7D) after the SSC exercise. Kinematics, force and electromyography (EMG) recordings were complemented with inverse dynamics, which was used to calculate joint moments. The quotient of changes in joint moment divided by changes in joint angle was used as a value of joint stiffness (JS). In addition, blood lactate concentrations and serum creatine kinase activities were determined. The exercise induced a clear decrease in knee joint stiffness by [mean (SD)] 29 (13)% (P < 0.05) in HOP, 31 (6)% (P < 0.05) in DJ35 and 34 (14)% (P < 0.05) in DJ55. A similar trend was observed in the ankle joint stiffness with significant post-exercise reductions of 22 (8)% (P < 0.05) in DJ35 and of 27 (19)% (P < 0.05) at 2H in DJ55. The subsequent recovery of JS was slow and in some cases incomplete still at 7D. Generally, all the EMG parameters were fully recovered by 2H, whereas the force recovery was still incomplete at this time. These data indicate that the immediate reduction in JS was probably related to the effects of both central (neural) and peripheral (metabolic) fatigue, whereas the prolonged impairment was probably due to peripheral fatigue (muscle damage).
Does continuous endurance exercise in water elicit a higher release of ANP and BNP and a higher plasma concentration of FFAs in pre-obese and obese men than high intensity intermittent endurance exercise? – Study protocol for a randomized controlled trial
Background Atrial natriuretic peptides (ANP) and Brain natriuretic peptides (BNP) stimulate fat cell plasma membrane receptors. They are potent lipolytic agents on isolated fat cells from subcutaneous adipose tissue. The physiological effects of continuous endurance exercise on ANP release and plasma free fatty acids (FFA) concentrations have been well described. The enhancement of fat metabolism using high intensity intermittent exercise protocols has been assessed in more recent investigations. The combined effects of endurance exercise and water immersion on ANP and FFA plasma concentration and the magnitude of excess post-exercise oxygen consumption (EPOC) might be further enhanced by choosing the most effective exercise protocol. Exercise modalities may play a significant role in the future prevention and treatment of obesity. Methods/design The two testing trials will be performed according to a randomized and cross-over design. Twenty healthy sedentary pre-obese and obese class-1 men will be scrutinized with regard to their metabolic responses to continuous exercise in water and to high intensity endurance exercise in water. Both trials will be matched for energy expenditure. After preliminary testing, the tests will be conducted as repeated measurements. The two different exercise protocols will be compared. The aims of the study are to investigate (1) whether continuous endurance exercise or high intensity intermittent endurance exercise in water elicits both a higher release of ANP and BNP and a higher plasma concentration of glycerol and (2) to determine whether continuous endurance exercise in water or a high intensity intermittent endurance exercise in water would lead to a more pronounced short term (two hours) EPOC effect. Discussion If our hypothesis would be confirmed, the most effective exercise protocol based on the combined effects of high intensity endurance exercise and water immersion on ANP and BNP release and glycerol plasma concentrations
Pascual, Julio; González-Mandly, Andrés; Martín, Rubén; Oterino, Agustín
Headaches provoked by cough, prolonged physical exercise and sexual activity have not been studied prospectively, clinically and neuroradiologically. Our aim was to delimitate characteristics, etiology, response to treatment and neuroradiological diagnostic protocol of those patients who consult to a general Neurological Department because of provoked headache. Those patients who consulted due to provoked headaches between 1996 and 2006 were interviewed in depth and followed-up for at least 1 year. Neuroradiological protocol included cranio-cervical MRI for all patients with cough headache and dynamic cerebrospinal functional MRI in secondary cough headache cases. In patients with headache provoked by prolonged physical exercise or/and sexual activity cranial neuroimaging (CT and/or MRI) was performed and, in case of suspicion of subarachnoid bleeding, angioMRI and/or lumbar tap were carried out. A total of 6,412 patients consulted due to headache during the 10 years of the study. The number of patients who had consulted due to any of these headaches is 97 (1.5% of all headaches). Diagnostic distribution was as follows: 68 patients (70.1%) consulted due to cough headache, 11 (11.3%) due to exertional headache and 18 (18.6%) due to sexual headache. A total of 28 patients (41.2%) out of 68 were diagnosed of primary cough headache, while the remaining 40 (58.8%) had secondary cough headache, always due to structural lesions in the posterior fossa, which in most cases was a Chiari type I malformation. In seven patients, cough headache was precipitated by treatment with angiotensin-converting enzyme inhibitors. As compared to the primary variety, secondary cough headache began earlier (average 40 vs. 60 years old), was located posteriorly, lasted longer (5 years vs. 11 months), was associated with posterior fossa symptoms/signs and did not respond to indomethacin. All those patients showed difficulties in the cerebrospinal fluid circulation in the foramen magnum region
Ferguson, Carrie; Wylde, Lindsey A; Benson, Alan P; Cannon, Daniel T; Rossiter, Harry B
During whole body exercise in health, maximal oxygen uptake (V̇o2max) is typically attained at or immediately before the limit of tolerance (LoT). At the V̇o2max and LoT of incremental exercise, a fundamental, but unresolved, question is whether maximal evocable power can be increased above the task requirement, i.e., whether there is a "power reserve" at the LoT. Using an instantaneous switch from cadence-independent (hyperbolic) to isokinetic cycle ergometry, we determined maximal evocable power at the limit of ramp-incremental exercise. We hypothesized that in endurance-trained men at LoT, maximal (4 s) isokinetic power would not differ from the power required by the task. Baseline isokinetic power at 80 rpm (Piso; measured at the pedals) and summed integrated EMG from five leg muscles (ΣiEMG) were measured in 12 endurance-trained men (V̇o2max = 4.2 ± 1.0 l/min). Participants then completed a ramp incremental exercise test (20-25 W/min), with instantaneous measurement of Piso and ΣiEMG at the LoT. Piso decreased from 788 ± 103 W at baseline to 391 ± 72 W at LoT, which was not different from the required ramp-incremental flywheel power (352 ± 58 W; P > 0.05). At LoT, the relative reduction in Piso was greater than the relative reduction in the isokinetic ΣiEMG (50 ± 9 vs. 63 ± 10% of baseline; P < 0.05). During maximal ramp incremental exercise in endurance-trained men, maximum voluntary power is not different from the power required by the task and is consequent to both central and peripheral limitations in evocable power. The absence of a power reserve suggests both the perceptual and physiological limits of maximum voluntary power production are not widely dissociated at LoT in this population.
Takeshima, Keisuke; Onitsuka, Sumire; Xinyan, Zheng; Hasegawa, Hiroshi
It has been demonstrated that precooling with ice slurry ingestion enhances endurance exercise capacity in the heat. However, no studies have yet evaluated the optimal timing of ice slurry ingestion for precooling. This study aimed to investigate the effects of varying the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment. Ten active male participants completed 3 experimental cycling trials to exhaustion at 55% peak power output (PPO) after 15min of warm-up at 30% PPO at 30°C and 80% relative humidity. Three experimental conditions were set: no ice slurry ingestion (CON), pre-warm-up ice slurry ingestion (-1°C; 7.5gkg(-1)) (PRE), and post-warm-up ice slurry ingestion (POST). Rectal and mean skin temperatures at the beginning of exercise in the POST condition (37.1±0.2°C, 33.8±0.9°C, respectively) were lower than those in the CON (37.5±0.3°C; P<0.001, 34.8±0.8°C; P<0.01, respectively) and PRE (37.4±0.2°C; P<0.01, 34.6±0.7°C; P<0.01, respectively) conditions. These reductions increased heat storage capacity and resulted in improved exercise capacity in the POST condition (60.2±8.7min) compared to that in the CON (52.0±11.9min; effect size [ES]=0.78) and PRE (56.9±10.4min; ES=0.34) conditions. Ice slurry ingestion after warm-up effectively reduced both rectal and skin temperatures and increased cycling time to exhaustion in a warm environment. Timing ice slurry ingestion to occur after warm-up may be effective for precooling in a warm environment.
Heaney, Jennifer L J; Phillips, Anna C; Drayson, Mark T; Campbell, John P
Traditionally, free light chains (FLCs) are used as key serum biomarkers in the diagnosis and monitoring of plasma cell malignancies, but polyclonal FLCs can also be used as an accurate real-time indicator of immune-activation and inflammation. The primary aim of the present study was to assess the effects of exercise training status on serum FLCs in older adults, and secondly, to examine if training status moderated serum FLC responses to acute exercise. Kappa and lambda serum FLC levels were measured in 45 healthy older adults (aged ≥ 60 years) who were either sedentary, physically active or endurance trained. FLCs were measured at baseline and in response to an acute bout of submaximal exercise. The endurance trained group had significantly lower levels of kappa and lambda serum FLCs compared with physically active or sedentary elderly adults; these effects were independent of age, BMI and renal function. There was no significant difference in whole immunoglobulins between groups. Exercise training status had no effect on serum FLC responses to acute exercise, which were marginal. In conclusion, endurance training was associated with lower FLC levels compared with less physically active individuals. These findings suggest that long-term endurance training may be beneficial in reducing basal inflammation in older adults as well as elevated FLCs present in inflammatory and autoimmune conditions, often associated with ageing. FLCs may serve as a useful biomarker for monitoring the efficacy of exercise intervention studies in healthy and clinical populations.
Williams, Cameron B; Zelt, Jason G E; Castellani, Laura N; Little, Jonathan P; Jung, Mary E; Wright, David C; Tschakovsky, Michael E; Gurd, Brendon J
The purpose of this study was to investigate the acute effects of endurance exercise (END; 65% V̇O2peak for 60 min) and high-intensity interval exercise (HIE; four 30 s Wingates separated by 4.5 min of active rest) on cardiorespiratory, hormonal, and subjective appetite measures that may account for the previously reported superior fat loss with low volume HIE compared with END. Recreationally active males (n = 18) completed END, HIE, and control (CON) protocols. On each test day, cardiorespiratory measures including oxygen uptake (V̇O2), respiratory exchange ratio (RER), and heart rate were recorded and blood samples were obtained at baseline (BSL), 60 min after exercise, and 180 min after exercise (equivalent times for CON). Subjective measures of appetite (hunger, fullness, nausea, and prospective consumption) were assessed using visual analogue scales, administered at BSL, 0, 60, 120, and 180 min after exercise. No significant differences in excess postexercise oxygen consumption (EPOC) were observed between conditions. RER was significantly (P < 0.05) depressed in HIE compared with CON at 60 min after exercise, yet estimates of total fat oxidation over CON were not different between HIE and END. No differences in plasma adiponectin concentrations between protocols or time points were present. Epinephrine and norepinephrine were significantly (P < 0.05) elevated immediately after exercise in HIE compared with CON. Several subjective measures of appetite were significantly (P < 0.05) depressed immediately following HIE. Our data indicate that increases in EPOC or fat oxidation following HIE appear unlikely to contribute to the reported superior fat loss compared with END.
Scherer, T A; Spengler, C M; Owassapian, D; Imhof, E; Boutellier, U
Inspiratory muscle training may have beneficial effects in certain patients with chronic obstructive pulmonary disease (COPD). Because of the lack of a home training device, normocapnic hyperpnea has rarely been used as a training mode for patients with COPD, and is generally considered unsuitable to large-scale application. To study the effects of hyperpnea training, we randomized 30 patients with COPD and ventilatory limitation to respiratory muscle training (RMT; n = 15) with a new portable device or to breathing exercises with an incentive spirometer (controls; n = 15). Both groups trained twice daily for 15 min for 5 d per week for 8 wk. Training-induced changes were significantly greater in the RMT than in the control group for the following variables: respiratory muscle endurance measured through sustained ventilation (+825 +/- 170 s [mean +/- SEM] versus -27 +/- 61 s, p < 0.001), inspiratory muscle endurance measured through incremental inspiratory threshold loading (+58 +/- 10 g versus +21.7 +/- 9.5 g, p = 0.016), maximal expiratory pressure (+20 +/- 7 cm H(2)O versus -6 +/- 6 cm H(2)O, p = 0.009), 6-min walking distance (+58 +/- 11 m versus +11 +/- 11 m, p = 0.002), V O(2peak) (+2.5 +/- 0.6 ml/kg/min versus -0.3 +/- 0.9 ml/kg/min, p = 0.015), and the SF-12 physical component score (+9.9 +/- 2.7 versus +1.8 +/- 2.4, p = 0.03). Changes in dyspnea, maximal inspiratory pressure, treadmill endurance, and the SF-12 mental component score did not differ significantly between the RMT and control groups. In conclusion, home-based respiratory muscle endurance training with the new device used in this study is feasible and has beneficial effects in subjects with COPD and ventilatory limitation.
Koska, Juraj; Ksinantová, Lucia; Kvetnanský, Richard; Hamar, Dusan; Martinkovic, Miroslav; Vigas, Milan
The study was designed to evaluate how a bout of endurance training (ET) influences the endocrine response after head-down bed rest (HDBR). Eleven healthy males completed the study, which consisted of a 6-wk ET followed by 5 days of -6 degrees head-down HDBR. Treadmill exercise at 80% of pretraining maximal aerobic capacity (VO(2max)) was performed before and after ET as well as after HDBR. ET increased VO(2max) by 13%. The response of norepinephrine was attenuated after ET and exaggerated after HDBR (P < 0.001). The differences in epinephrine responses were not statistically significant. The responses of cortisol and plasma renin activity (PRA) were unchanged after ET and were enhanced after HDBR (P < 0.001). The response of growth hormone after HDBR was reduced (P < 0.05). Only the change in cortisol response was associated with the increment of VO(2max) after ET (r = 0.68, P < 0.01). Endurance training failed to completely prevent changes in endocrine responses seen after HDBR. Improvement of physical fitness was associated with an enhancement of the cortisol response to exercise following the period of bed rest.
Zaccaria, M; Varnier, M; Piazza, P; Noventa, D; Ermolao, A
The purpose of this study was to evaluate the GH response to exercise and the effects of endurance training on this response in early middle-aged men. Seven healthy middle-aged [M; 42.0+/-2.4 (+/-SD) yr old] and five young (Y; 21.2+/-1.1 yr old) competition cyclists were investigated before and after 4 months of intensive endurance training. Subjects performed an exhaustive incremental exercise test (50 watts for 3 min) with gas exchange measurement, and blood samples for lactate, glucose, and GH determinations were drawn before exercise, at the end of the exercise, and in the recovery phase (1, 3, 5, 10, 15, 20, and 30 min). Basal insulin-like growth factor I was also determined. At exhaustion no differences were found in relative maximal heart rate or blood lactate and glucose peaks. On the contrary, the two groups had markedly different GH responses; in fact, the peak GH response to exhaustive exercise was much lower in M than in Y (8.1+/-1.3 vs. 57.1+/-15.5 microg/L; P<0.01). The training, similar in subjects of the same group, increased progressively from 182 to 300 km/week (+64.8%) in M and from 350 to 600 km/week (+71.4%) in Y. After the training, the percent increase in maximal oxygen consumption was similar in the two groups (M, +15.2%; Y, +17.5%), confirming that the efficiency of the training performed was comparable. In neither group did training have any effect on the GH peak response to exercise, confirming the blunted GH response in M compared to Y (6.7+/-1.0 vs. 61.0+/-12.9 microg/L; P<0.01). Similarly, insulin-like growth factor I concentrations were not significantly affected by training. In conclusion, active middle-aged subjects, compared with the young, showed a blunted GH response to a physiological stimulus such as exercise, indicating that the age-related decline in GH secretion appears in early middle age. This response was not modified by training in either early middle-aged or young subjects.
Pageaux, Benjamin; Lepers, Romuald
Endurance performance involves the prolonged maintenance of constant or self-regulated power/velocity or torque/force. While the impact of numerous determinants of endurance performance has been previously reviewed, the impact of fatigue on subsequent endurance performance still needs to be documented. This review aims to present the impact of fatigue induced by physical or mental exertion on subsequent endurance performance. For the purpose of this review, endurance performance refers to performance during whole-body or single-joint endurance exercise soliciting mainly the aerobic energy system. First, the impact of physical and mental exertion on force production capacity is presented, with specific emphasize on the fact that solely physical exertion and not mental exertion induces a decrease in force production capacity of the working muscles. Then, the negative impact of fatigue induced by physical exertion and mental exertion on subsequent endurance performance is highlighted based on experimental data. Perception of effort being identified as the variable altered by both prior physical exertion and mental exertion, future studies should investigate the underlying mechanisms increasing perception of effort overtime and in presence of fatigue during endurance exercise. Perception of effort should be considered not only as marker of exercise intensity, but also as a factor limiting endurance performance. Therefore, using a psychophysiological approach to explain the regulation of endurance performance would allow a better understanding of the interaction between physiological and psychological phenomena known to impact endurance performance. PMID:27965592
JanssenDuijghuijsen, Lonneke M.; van Norren, Klaske; Grefte, Sander; Koppelman, Stef J.; Lenaerts, Kaatje; Keijer, Jaap; Witkamp, Renger F.; Wichers, Harry J.
Controlled studies on the effect of exercise on intestinal uptake of protein are scarce and underlying mechanisms largely unclear. We studied the uptake of the major allergen Ara h 6 following peanut consumption in an exercise model and compared this with changes in markers of intestinal permeability and integrity. Ten overnight-fasted healthy non-allergic men (n = 4) and women (n = 6) (23 ± 4 years) ingested 100 g of peanuts together with a lactulose/rhamnose (L/R) solution, followed by rest or by 60 min cycling at 70% of their maximal workload. Significantly higher, though variable, levels of Ara h 6 in serum were found during exercise compared to rest (Peak p = 0.03; area under the curve p = 0.006), with individual fold changes ranging from no increase to an increase of over 150-fold in the uptake of Ara h 6. Similarly, uptake of lactulose (2–18 fold change, p = 0.0009) and L/R ratios (0.4–7.9 fold change, p = 0.04) were significantly increased which indicates an increase in intestinal permeability. Intestinal permeability and uptake of Ara h 6 were strongly correlated (r = 0.77, p < 0.0001 for lactulose and Ara h 6). Endurance exercise after consumption may lead to increased paracellular intestinal uptake of food proteins. PMID:28117717
Otani, Hidenori; Kaya, Mitsuharu; Tsujita, Junzo
This study examined the effect of the volume of fluid ingested on urine concentrating ability during prolonged heavy exercise in a hot environment at low levels of dehydration. Seven healthy males performed 105 min of intermittent cycle exercise at 70% maximum oxygen uptake (32°C, 60% relative humidity) while receiving no fluid ingestion (NF), voluntary fluid ingestion (VF), partial fluid ingestion equivalent to one-half of body mass loss (PF), and full fluid ingestion equivalent to body mass loss (FF). Fluid (5°C, 3.4% carbohydrate, 10.5 mmol·L-1 sodium) was ingested just before commencing exercise and at 15, 33, 51, 69, and 87 min of exercise, and the total amount of fluid ingested in PF and FF was divided into six equal volumes. During exercise, body mass loss was 2.2 ± 0.2, 1.1 ± 0.5, 1.1 ± 0.2, and 0.1 ± 0.2% in NF, VF, PF, and FF, respectively, whereas total sweat loss was about 2% of body mass in each trial. Subjects in VF ingested 719 ± 240 ml of fluid during exercise; the volume of fluid ingested was 1.1 ± 0.4% of body mass. Creatinine clearance was significantly higher and free water clearance was significantly lower in FF than in NF during exercise. Urine flow rate during exercise decreased significantly in NF. There were significant decreases in creatinine and osmolar clearance and was a significant increase in free water clearance during exercise in NF and VF. Creatinine clearance decreased significantly and free water clearance increased significantly during exercise in PF. There was no statistical change in urinary indices of renal function during exercise in FF. The findings suggest that full fluid ingestion equivalent to body mass loss has attenuated the decline in urine concentrating ability during prolonged heavy exercise in a hot environment at low levels of dehydration. Key points During prolonged heavy exercise in a hot environment at low levels of dehydration, fluid ingestion equivalent to body mass loss results in no changes in
Świątkiewicz, Maciej; Fiedorowicz, Michał; Orzeł, Jarosław; Wełniak-Kamińska, Marlena; Bogorodzki, Piotr; Langfort, Józef; Grieb, Paweł
may be a result of functional activation caused by forced endurance exercise; the increased rate of ammonia detoxification may also contribute. Increases in glutamate in the cerebellum and hippocampus are suggestive of an anaplerotic increase in glutamate synthesis due to exercise-related stimulation of brain glucose uptake. The disequilibrium in the glutamate-glutamine cycle in brain areas activated during exercise may be a significant contributor to the central fatigue phenomenon. PMID:28197103
Świątkiewicz, Maciej; Fiedorowicz, Michał; Orzeł, Jarosław; Wełniak-Kamińska, Marlena; Bogorodzki, Piotr; Langfort, Józef; Grieb, Paweł
-Gln cycle may be a result of functional activation caused by forced endurance exercise; the increased rate of ammonia detoxification may also contribute. Increases in glutamate in the cerebellum and hippocampus are suggestive of an anaplerotic increase in glutamate synthesis due to exercise-related stimulation of brain glucose uptake. The disequilibrium in the glutamate-glutamine cycle in brain areas activated during exercise may be a significant contributor to the central fatigue phenomenon.
West, Amy D; Cooke, Matthew B; LaBounty, Paul M; Byars, Allyn G; Greenwood, Mike
The purpose of this study was to compare the effectiveness of 3 treatment modes (Anti-Gravity Treadmill [G-trainer], stationary cycling [CompuTrainer], and static stretching) on the physiological and psychological recovery after an acute bout of exhaustive exercise. In a crossover design, 12 aerobically trained men (21.3 ± 2.3 years, 72.1 ± 8.1 kg, 178.4 ± 6.3 cm, (Equation is included in full-text article.): 53.7 ± 6.3 ml·kg·min) completed a 29-km stationary cycling time trial. Immediately after the time trial, subjects completed 30 minutes of G-trainer or CompuTrainer (40% (Equation is included in full-text article.)) or static stretching exercises. A significant time effect was detected for plasma lactate (p = 0.010) and serum cortisol (p = 0.039) after exercise. No treatment or treatment by time interaction was identified for lactate or cortisol, respectively. No main effects for time, treatment, or treatment by time interaction were identified for interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α). No differences were observed among treatments in skeletal muscle peak power output, mean power output, time to peak power, and rate to fatigue at 24 hours postexercise bout. Finally, no significant changes in mood status were observed after exercise and between treatment groups. When compared with stationary cycling and static stretching, exercise recovery performed on the G-trainer was unable to reduce systemic markers of stress and inflammation, blood lactate, or improve anaerobic performance and psychological mood states after an exhaustive bout of endurance exercise. Further research is warranted that includes individualized recovery modalities to create balances between the stresses of training and competition.
McKenna, Michael J; Medved, Ivan; Goodman, Craig A; Brown, Malcolm J; Bjorksten, Andrew R; Murphy, Kate T; Petersen, Aaron C; Sostaric, Simon; Gong, Xiaofei
Reactive oxygen species (ROS) have been linked with both depressed Na+,K+-pump activity and skeletal muscle fatigue. This study investigated N-acetylcysteine (NAC) effects on muscle Na+,K+-pump activity and potassium (K+) regulation during prolonged, submaximal endurance exercise. Eight well-trained subjects participated in a double-blind, randomised, crossover design, receiving either NAC or saline (CON) intravenous infusion at 125 mg kg−1 h−1 for 15 min, then 25 mg kg−1 h−1 for 20 min prior to and throughout exercise. Subjects cycled for 45 min at 71% V˙O2peak, then continued at 92% V˙O2peak until fatigue. Vastus lateralis muscle biopsies were taken before exercise, at 45 min and fatigue and analysed for maximal in vitro Na+,K+-pump activity (K+-stimulated 3-O-methyfluorescein phosphatase; 3-O-MFPase). Arterialized venous blood was sampled throughout exercise and analysed for plasma K+ and other electrolytes. Time to fatigue at 92% V˙O2peak was reproducible in preliminary trials (c.v. 5.6 ± 0.6%) and was prolonged with NAC by 23.8 ± 8.3% (NAC 6.3 ± 0.5 versus CON 5.2 ± 0.6 min, P < 0.05). Maximal 3-O-MFPase activity decreased from rest by 21.6 ± 2.8% at 45 min and by 23.9 ± 2.3% at fatigue (P < 0.05). NAC attenuated the percentage decline in maximal 3-O-MFPase activity (%Δactivity) at 45 min (P < 0.05) but not at fatigue. When expressed relative to work done, the %Δactivity-to-work ratio was attenuated by NAC at 45 min and fatigue (P < 0.005). The rise in plasma [K+] during exercise and the Δ[K+]-to-work ratio at fatigue were attenuated by NAC (P < 0.05). These results confirm that the antioxidant NAC attenuates muscle fatigue, in part via improved K+ regulation, and point to a role for ROS in muscle fatigue. PMID:16840514
Kraemer, R R; Shockett, P; Webb, N D; Shah, U; Castracane, V D
Irisin, a newly discovered, PGC-1α dependent myokine, has recently been shown to increase in circulation in response to sprint exercise. This study examined the effect of prolonged exercise on irisin concentrations in young men (n=7) as well as in young women (n=5) during different stages of the menstrual cycle. Seven young men completed 90 min of treadmill exercise at 60% of VO2max and a resting control trial. Five women completed the same exercise protocol in two different trials: during the early follicular phase and mid-luteal phase of the menstrual cycle. Blood samples were collected and analyzed for irisin concentrations immediately before exercise, at 54 and 90 min of exercise, and at 20 min of recovery (R20). Findings revealed that by 54 min of a 90 min treadmill exercise protocol at 60% of VO2max, irisin concentrations significantly increased 20.4% in young men and 20.3% as well as 24.6% in young women during the early follicular and mid-luteal phases of the menstrual cycle, respectively. However, by 90 min of exercise as well as R20, irisin concentrations were no longer elevated. Stage of the menstrual cycle did not affect responses in young women. Findings indicate that prolonged aerobic exercise produces a transient increase in irisin concentrations during the first hour of exercise for both genders and suggest that this form of moderate exercise may be helpful in improving fat metabolism.
Suvi, Silva; Timpmann, Saima; Tamm, Maria; Aedma, Martin; Kreegipuu, Kairi; Ööpik, Vahur
Acute caffeine ingestion is considered effective in improving endurance capacity and psychological state. However, current knowledge is based on the findings of studies that have been conducted on male subjects mainly in temperate environmental conditions, but some physiological and psychological effects of caffeine differ between the sexes. The purpose of this study was to compare the physical performance and psychological effects of caffeine in young women and men exercising in the heat. Thirteen male and 10 female students completed 2 constant-load walks (60% of thermoneutral peak oxygen consumption on a treadmill until volitional exhaustion) in a hot-dry environment (air temperature, 42 °C; relative humidity, 20%) after caffeine (6 mg·kg(-1)) and placebo (wheat flour) ingestion in a double-blind, randomly assigned, crossover manner. Caffeine, compared with placebo, induced greater increases (p < 0.05) in heart rate (HR) and blood lactate concentrations in both males and females but had no impact on rectal or skin temperatures or on walking time to exhaustion in subjects of either gender. Caffeine decreased (p < 0.05) ratings of perceived exertion and fatigue in males, but not in females. In females, but not in males, a stronger belief that they had been administered caffeine was associated with a shorter time to exhaustion. In conclusion, acute caffeine ingestion increases HR and blood lactate levels during exercise in the heat, but it has no impact on thermoregulation or endurance capacity in either gender. Under exercise-heat stress, caffeine reduces ratings of perceived exertion and fatigue in males but not in females.
Landers-Ramos, Rian Q.; Sapp, Ryan M.; Jenkins, Nathan T.; Murphy, Anna E.; Cancre, Lucile; Chin, Eva R.; Spangenburg, Espen E.
We aimed to determine if chronic endurance-exercise habits affected redox status and paracrine function of CD34+ and CD34−/CD31+ circulating angiogenic cells (CACs). Subjects were healthy, nonsmoking men and women aged 18–35 yr and categorized by chronic physical activity habits. Blood was drawn from each subject for isolation and culture of CD34+ and CD34−/CD31+ CACs. No differences in redox status were found in any group across either cell type. Conditioned media (CM) was generated from the cultured CACs and used in an in vitro human umbilical vein endothelial cell-based tube assay. CM from CD34+ cells from inactive individuals resulted in tube structures that were 29% shorter in length (P < 0.05) and 45% less complex (P < 0.05) than the endurance-trained group. CD34−/CD31+ CM from inactive subjects resulted in tube structures that were 26% shorter in length (P < 0.05) and 42% less complex (P < 0.05) than endurance-trained individuals. Proteomics analyses identified S100A8 and S100A9 in the CM. S100A9 levels were 103% higher (P < 0.05) and S100A8 was 97% higher in the CD34−/CD31+ CM of inactive subjects compared with their endurance-trained counterparts with no significant differences in either protein in the CM of CD34+ CACs as a function of training status. Recombinant S100A8/A9 treatment at concentrations detected in inactive subjects' CD34−/CD31+ CAC CM also reduced tube formation (P < 0.05). These findings are the first, to our knowledge, to demonstrate a differential paracrine role in CD34+ and CD34−/CD31+ CACs on tube formation as a function of chronic physical activity habits and identifies a differential secretion of S100A9 by CD34−/CD31+ CACs due to habitual exercise. PMID:26055789
Pritchett, Kelly; Pritchett, Robert
An optimal post-exercise nutrition regimen is fundamental for ensuring recovery. Therefore, research has aimed to examine post-exercise nutritional strategies for enhanced training stimuli. Chocolate milk has become an affordable recovery beverage for many athletes, taking the place of more expensive commercially available recovery beverages. Low-fat chocolate milk consists of a 4:1 carbohydrate:protein ratio (similar to many commercial recovery beverages) and provides fluids and sodium to aid in post-workout recovery. Consuming chocolate milk (1.0-1.5•g•kg(-1) h(-1)) immediately after exercise and again at 2 h post-exercise appears to be optimal for exercise recovery and may attenuate indices of muscle damage. Future research should examine the optimal amount, timing, and frequency of ingestion of chocolate milk on post-exercise recovery measures including performance, indices of muscle damage, and muscle glycogen resynthesis.
You, Yu-Lin; Su, Tzu-Kai; Liaw, Lih-Jiun; Wu, Wen-Lan; Chu, I-Hua; Guo, Lan-Yuen
[Purpose] The purpose of this study was to investigate the effects of 6 weeks sling exercise training for clients with low back pain on the levels of pain, disability, muscular strength and endurance. [Subjects and Methods] Twelve chronic LBP subjects participated in this study. Subjects were randomly divided into a control group and a training group. Subjects in the training group performed sling exercise training for six weeks, and participants in the control group did not perform any exercise. [Results] Pain, disability levels and muscular strength significantly improved in the training group, but not in the control group. The left multifidus showed a significant improvement in muscular endurance, measured as the slope of the median frequency after training. [Conclusion] Six weeks of sling exercise training was effective at reducing pain intensity, and improving the disability level and trunk muscular strength of subjects with low back pain. PMID:26356255
Ogwumike, O O; Arowojolu, A O; Sanya, A O
Menopause is a sign of aging in the woman. Loss of ovarian function induces a reduction in resting metabolic rate, physical energy expenditure, fat-free mass and abdominal adipose tissue accumulation. Location of adipose tissue deposit in abdominal region plays an important role in occurrence of hyperlipidemia, diabetes, hypertension and atherosclerosis. Although regular participation in physical exercise have been suggested to improve adiposity and body flexibility which are important health related components of physical fitness, few published studies are available on the effect of exercise on Nigerian menopausal women. This study investigated effects of a twelve-week endurance exercise program (EEP) on central and abdominal obesity as well as flexibility of perimenopausal and postmenopausal Nigerian women. The study employed a pretest- posttest control group design comprising a sample of 175 apparently healthy, literate, sedentary women within age range 40-59 years. They were workers in state and federal establishments in Ibadan North Local Government Area of Oyo State, Nigeria. Based on history of their last menstrual period, women with regular or irregular menstrual cycle status were allocated into perimenopausal group and those who no longer menstruated into postmenopausal group. A table of random numbers was used for further allocation into perimenopausal exercise group (PEMEG, 45), postmenopausal exercise group (POMEG, 45) perimenopausal control group (PEMCG, 42) and postmenopausal control group (POMCG, 43). Waist Hip Ratio (WHR), Body Mass Index (BMI) as well as Hip and Trunk Flexibility (HTF) were evaluated at baseline and 4weekly intervals until end of 12th week. EEP consisted of a 10-station circuit of cardiovascular endurance, flexibility, coordination, abdominal and pelvic floor muscle exercises. Data were analyzed using descriptive and inferential statistics. Mean age of participants was 52.3±4.1 years, 95% C.I (51.64-52.88) years. Significant
Iaia, F Marcello; Hellsten, Ylva; Nielsen, Jens Jung; Fernström, Maria; Sahlin, Kent; Bangsbo, Jens
We studied the effect of an alteration from regular endurance to speed endurance training on muscle oxidative capacity, capillarization, as well as energy expenditure during submaximal exercise and its relationship to mitochondrial uncoupling protein 3 (UCP3) in humans. Seventeen endurance-trained runners were assigned to either a speed endurance training (SET; n = 9) or a control (Con; n = 8) group. For a 4-wk intervention (IT) period, SET replaced the ordinary training ( approximately 45 km/wk) with frequent high-intensity sessions each consisting of 8-12 30-s sprint runs separated by 3 min of rest (5.7 +/- 0.1 km/wk) with additional 9.9 +/- 0.3 km/wk at low running speed, whereas Con continued the endurance training. After the IT period, oxygen uptake was 6.6, 7.6, 5.7, and 6.4% lower (P < 0.05) at running speeds of 11, 13, 14.5, and 16 km/h, respectively, in SET, whereas remained the same in Con. No changes in blood lactate during submaximal running were observed. After the IT period, the protein expression of skeletal muscle UCP3 tended to be higher in SET (34 +/- 6 vs. 47 +/- 7 arbitrary units; P = 0.06). Activity of muscle citrate synthase and 3-hydroxyacyl-CoA dehydrogenase, as well as maximal oxygen uptake and 10-km performance time, remained unaltered in both groups. In SET, the capillary-to-fiber ratio was the same before and after the IT period. The present study showed that speed endurance training reduces energy expenditure during submaximal exercise, which is not mediated by lowered mitochondrial UCP3 expression. Furthermore, speed endurance training can maintain muscle oxidative capacity, capillarization, and endurance performance in already trained individuals despite significant reduction in the amount of training.
Min, Pil-Ki; Park, Joseph; Isaacs, Stephanie; Taylor, Beth A; Thompson, Paul D; Troyanos, Chris; D'Hemecourt, Pierre; Dyer, Sophia; Chan, Stephen Y; Baggish, Aaron L
Statins exacerbate exercise-induced skeletal muscle injury. Muscle-specific microRNAs (myomiRs) increase in plasma after prolonged exercise, but the patterns of myomiRs release after statin-associated muscle injury have not been examined. We examined the relationships between statin exposure, in vitro and in vivo muscle contraction, and expression of candidate circulating myomiRs. We measured plasma levels of myomiRs, circulating microRNA-1 (c-miR-1), c-miR-133a, c-miR-206, and c-miR-499-5p from 28 statin-using and 28 nonstatin-using runners before (PRE), immediately after (FINISH), and 24 h after they ran a 42-km footrace (the 2011 Boston marathon) (POST-24). To examine these cellular-regulation myomiRs, we used contracting mouse C2C12 myotubes in culture with and without statin exposure to compare intracellular and extracellular expression of these molecules. In marathoners, c-miR-1, c-miR-133a, and c-miR-206 increased at FINISH, returned to baseline at POST-24, and were unaffected by statin use. In contrast, c-miR-499-5p was unchanged at FINISH but increased at POST-24 among statin users compared with PRE and runners who did not take statins. In cultured C2C12 myotubes, extracellular c-miR-1, c-miR-133a, and c-miR-206 were significantly increased by muscle contraction regardless of statin use. In contrast, extracellular miR-499-5p was unaffected by either isolated statin exposure or isolated carbachol exposure but it was increased when muscle contraction was combined with statin exposure. In summary, we found that statin-potentiated muscle injury during exercise is accompanied by augmented extracellular release of miR-499-5p. Thus c-miR-499-5p may serve as a biomarker of statin-potentiated muscle damage.
Smorawinski, J.; Nazar, K.; Kaciuza-Uscilko; Kaminska, E.; Kodrzycka, A.; Bicz, B.; Greenleaf, J. E.
To test the hypotheses that short-term bed rest (BR) deconditioning influences metabolic, cardiorespiratory and neurohormonal responses to exercise and that these effects depend on the subjects' training status, 12 sedentary men, and 10 endurance- and 10 strength-trained athletes were submitted to three-day BR. Before and after BR they performed incremental exercise tests until volitional exhaustion. Respiratory gas exchange and HR were recorded continuously and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate [LA], adrenaline [A], noradrenaline [NA], renin activity (PRA), growth hormone [hGH], testosterone and cortisol determination. Reduction of peak oxygen uptake (V02peak) after BR was greater in the endurance athletes than in the remaining groups (17 % vs. 10%). Decrements in VO2peak correlated positively with the initial values (r = 0.73, p is less than 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased the in endurance athletes from 71 to 60% V02 peak (p is less than0.001), they also had an earlier increase in [NA], an attenuated increase in [hGH], and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion: reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.
Smorawinski, J.; Nazar, K.; Kaciuza-Uscilko, H.; Kaminska, E.; Cybulski, G.; Kodrzycka, A.; Bice, B.; Greenleaf, J. E.; Sun, Sid (Technical Monitor)
To test the hypotheses that short-term bed rest (BR) deconditioning influences metabolic, cardiorespiratory and neurohormonal responses to exercise and that these effects depend on the subjects' training status 12 sedentary men, and 10 endurance- and 10 strength-trained athletes were submitted to three-day BR. Before and after BR they performed incremental exercise test until volitional exhaustion. Respiratory gas exchange and HR were recorded continuously and stroke volume (SV) was measured at submaximal loads. Blood was taken for lactate [LA], adrenaline [A], noradrenaline, [NA], renting activity (PRA), growth hormone [hGH], testosterone and cortisol determination. Reduction of peak oxygen uptake (VO2peak) after BR was greater in the endurance athletes (than in the remaining groups (17 % vs. 100%). Decrements in VO2peak correlated positively with the initial values (r = 0.73, p less than 0.001). Resting and exercise respiratory exchange ratios were increased in athletes. Cardiac output was unchanged by BR in all groups, but exercise HR was increased and SV diminished in the sedentary subjects. The submaximal [LA] and [LA] thresholds were decreased the in endurance athletes from 71 to 60 %VO2 peak (p less than 0.001); they also had an earlier increase in [NA], and an attenuated increase in [hGH), and accentuated PRA and cortisol elevations during exercise. These effects were insignificant in the remaining subjects. In conclusion: reduction of exercise performance and modifications in neurohormonal response to exercise after BR depend on the previous level and mode of physical training, being the most pronounced in the endurance athletes.
Peter N. Frykman and John F. Patton U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760; and Sargent College of Allied Health... maximum rate. The slowest process for ATP resynthesis is oxidative phosphorylation, which can operate for the longest period. Exercise at a given power...the highest power a subject can generate for one second, and not to the exercise intensity eliciting VO2 max’ which is usually less than one-third of
Collomp, K; Candau, R; Lasne, F; Labsy, Z; Préfaut, C; De Ceaurriz, J
The present study examined whether oral short-term administration of salbutamol (Sal) modifies performance and selected hormonal and metabolic variables during submaximal exercise. Eight recreational male athletes completed two cycling trials at 80-85% peak O(2) consumption until exhaustion after either gelatin placebo (Pla) or oral Sal (12 mg/day for 3 wk) treatment, according to a double-blind and randomized protocol. Blood samples were collected at rest, after 5, 10, and 15 min, and at exhaustion to determine growth hormone (GH), cortisol, testosterone, triiodothyronine (T(3)), C peptide, free fatty acid (FFA), blood glucose, lactate, and blood urea values. Time of cycling was significantly increased after chronic Sal intake (Sal: 30.5 +/- 3.1 vs. Pla: 23.7 +/- 1.6 min, P < 0.05). No change in any variable was found before cycling except a decrease in blood urea concentration and an increase in T(3) after Sal that remained significant throughout the exercise test (P < 0.05). Compared with rest, exercise resulted in a significant increase in GH, cortisol, testosterone, T(3), FFAs, and lactate and a decrease in C peptide after both treatments with higher exercise FFA levels and exhaustion GH concentrations after Sal (P < 0.05). Sal but not Pla significantly decreased exercise blood glucose levels. From these data, short-term Sal intake did appear to improve performance during intense submaximal exercise with concomitant increase in substrate availability and utilization, but the exact mechanisms involved need further investigation.
Lewis, Nathan A; Towey, Colin; Bruinvels, Georgie; Howatson, Glyn; Pedlar, Charles R
Exercise causes alterations in redox homeostasis (ARH). Measuring ARH in elite athletes may aid in the identification of training tolerance, fatigued states, and underperformance. To the best of our knowledge, no studies have examined ARH in elite male and female distance runners at sea level. The monitoring of ARH in athletes is hindered by a lack of reliable and repeatable in-the-field testing tools and by the rapid turnaround of results. We examined the effects of various exercise intensities on ARH in healthy (non-over-reached) elite male and female endurance athletes using clinical point-of-care (POC) redox tests, referred to as the free oxygen radical test (FORT) (pro-oxidant) and the free oxygen radical defence (FORD) (antioxidant). Elite male and female endurance athletes (n = 22) completed a discontinuous incremental treadmill protocol at submaximal running speeds and a test to exhaustion. Redox measures were analyzed via blood sampling at rest, warm-up, submaximal exercise, exhaustion, and recovery. FORD was elevated above rest after submaximal and maximal exercise, and recovery (p < 0.05, d = 0.87-1.55), with only maximal exercise and recovery increasing FORT (p < 0.05, d = 0.23-0.32). Overall, a decrease in oxidative stress in response to submaximal and maximal exercise was evident (p < 0.05, d = 0.46). There were no gender differences for ARH (p > 0.05). The velocity at lactate threshold (vLT) correlated with the FORD response at rest, maximal exercise, and recovery (p < 0.05). Using the clinical POC redox test, an absence of oxidative stress after exhaustive exercise is evident in the nonfatigued elite endurance athlete. The blood antioxidant response (FORD) to exercise appears to be related to a key marker of aerobic fitness: vLT.
Buono, Michael J.; Krippes, Taylor; Kolkhorst, Fred W.; Williams, Alexander T.; Cabrales, Pedro
Previous studies have reported that blood viscosity is significantly increased following exercise. However, these studies measured both pre- and post-exercise blood viscosity at 37 °C even though core and blood temperatures would be expected to have increased during the exercise. Consequently, the effect of exercise-induced hyperthermia on mitigating change in blood viscosity may have been missed. The purpose of this study was to isolate the effects of exercise-induced hemoconcentration and hyperthermia, as well as determine their combined effects, on blood viscosity. Nine subjects performed 2 h of moderate-intensity exercise in the heat (37 °C, 40% rH), which resulted in significant increases from pre-exercise values for rectal temperature (37.11 ± 0.35 °C to 38.76 ± 0.13 °C), hemoconcentration (hematocrit = 43.6 ± 3.6% to 45.6 ± 3.5%), and dehydration (Δbody weight = −3.6 ± 0.7%). Exercise-induced hemoconcentration significantly (P < 0.05) increased blood viscosity by 9% (3.97 to 4.30 cP at 300 s−1) while exercise-induced hyperthermia significantly decreased blood viscosity by 7% (3.97 to 3.70 cP at 300 s−1). However, when both factors were considered together, there was no overall change in blood viscosity (3.97 to 4.03 cP at 300 s−1). The effects of exercise-induced hemoconcentration, increased plasma viscosity, and increased red blood cell aggregation, all of which increased blood viscosity, were counterbalanced by increased RBC deformability (e.g., RBC membrane shear elastic modulus and elongation index) caused by the hyperthermia. Thus, blood viscosity remained unchanged following prolonged moderate-intensity exercise in the heat. PMID:26682653
Lee, Samuel; Leone, Teresa C; Rogosa, Lisa; Rumsey, John; Ayala, Julio; Coen, Paul M; Fitts, Robert H; Vega, Rick B; Kelly, Daniel P
PPARgamma coactivator-1 (PGC-1) α; ;and β serve as master transcriptional regulators of muscle mitochondrial functional capacity and are capable of enhancing muscle endurance when overexpressed in mice. We sought to determine whether muscle-specific transgenic overexpression of PGC-1β affects the detraining response following endurance training. First, we established and validated a mouse exercise training/detraining protocol. Secondly, we found that overexpression of PGC-1β in skeletal muscle of sedentary mice fully recapitulated the training response using multiple physiological and gene expression endpoints. Lastly, overexpression of PGC-1β during the detraining period resulted in a partial prevention of the detraining response. Specifically, an increase in ΔVO2max was maintained in trained mice with muscle overexpression of PGC-1β 6 weeks after cessation of training. However, other detraining responses, including changes in running performance and in situ 1/2 relaxation time (a measure of contractility) were not affected by overexpression of PGC-1β. We conclude that while activation of muscle PGC-1β is sufficient to drive the complete endurance phenotype in sedentary mice, it only partially prevents the detraining response following exercise training suggesting that the process of endurance detraining involves mechanisms beyond the reversal of muscle autonomous mechanisms involved in endurance fitness. In addition, the protocol described here should be useful for assessing early-stage proof-of-concept interventions in pre-clinical models of muscle disuse atrophy.
Vierck, H B; Darvin, M E; Lademann, J; Reisshauer, A; Baack, A; Sterry, W; Patzelt, A
Oxidative stress is supposed to be responsible for a diversity of diseases. For protection purposes, the human organism exhibits a line-up of antioxidant substances functioning as radical catchers. As a result of neutralization of free radicals, antioxidants are destroyed. Therefore, the degradation of the antioxidants can be utilized as an indirect parameter for the measurement of free radical formation. As physical exercise may also induce oxidative stress, the aim of the present study was to determine the antioxidant substances, and more precisely, the carotenoid concentration in the skin of male volunteers during different sportive exposures (cycling and running with two different exercise intensities) with resonance Raman spectroscopic measurements. The results revealed that moderate and high intensity cycling and running decrease the carotenoid concentration of the skin, whereas both sport disciplines and both exercise intensities revealed similar results. It can be concluded that above a certain threshold, physical exercise leads to oxidative stress also in the skin associated with the decrease in the antioxidant concentration. This gives rise to the impairment of the first defence line of the skin and means an increase in the risk of sun exposure-induced damage, e.g., when exercise training is performed outside. Nevertheless, it has to be emphasized that sport in general applied at moderate loads has predominantly positive effects on the health of humans especially concerning cardiovascular and metabolic diseases.
Mach, Núria; Plancade, Sandra; Pacholewska, Alicja; Lecardonnel, Jérôme; Rivière, Julie; Moroldo, Marco; Vaiman, Anne; Morgenthaler, Caroline; Beinat, Marine; Nevot, Alizée; Robert, Céline; Barrey, Eric
The adaptive response to extreme endurance exercise might involve transcriptional and translational regulation by microRNAs (miRNAs). Therefore, the objective of the present study was to perform an integrated analysis of the blood transcriptome and miRNome (using microarrays) in the horse before and after a 160 km endurance competition. A total of 2,453 differentially expressed genes and 167 differentially expressed microRNAs were identified when comparing pre- and post-ride samples. We used a hypergeometric test and its generalization to gain a better understanding of the biological functions regulated by the differentially expressed microRNA. In particular, 44 differentially expressed microRNAs putatively regulated a total of 351 depleted differentially expressed genes involved variously in glucose metabolism, fatty acid oxidation, mitochondrion biogenesis, and immune response pathways. In an independent validation set of animals, graphical Gaussian models confirmed that miR-21-5p, miR-181b-5p and miR-505-5p are candidate regulatory molecules for the adaptation to endurance exercise in the horse. To the best of our knowledge, the present study is the first to provide a comprehensive, integrated overview of the microRNA-mRNA co-regulation networks that may have a key role in controlling post-transcriptomic regulation during endurance exercise.
Mach, Núria; Plancade, Sandra; Pacholewska, Alicja; Lecardonnel, Jérôme; Rivière, Julie; Moroldo, Marco; Vaiman, Anne; Morgenthaler, Caroline; Beinat, Marine; Nevot, Alizée; Robert, Céline; Barrey, Eric
The adaptive response to extreme endurance exercise might involve transcriptional and translational regulation by microRNAs (miRNAs). Therefore, the objective of the present study was to perform an integrated analysis of the blood transcriptome and miRNome (using microarrays) in the horse before and after a 160 km endurance competition. A total of 2,453 differentially expressed genes and 167 differentially expressed microRNAs were identified when comparing pre- and post-ride samples. We used a hypergeometric test and its generalization to gain a better understanding of the biological functions regulated by the differentially expressed microRNA. In particular, 44 differentially expressed microRNAs putatively regulated a total of 351 depleted differentially expressed genes involved variously in glucose metabolism, fatty acid oxidation, mitochondrion biogenesis, and immune response pathways. In an independent validation set of animals, graphical Gaussian models confirmed that miR-21-5p, miR-181b-5p and miR-505-5p are candidate regulatory molecules for the adaptation to endurance exercise in the horse. To the best of our knowledge, the present study is the first to provide a comprehensive, integrated overview of the microRNA-mRNA co-regulation networks that may have a key role in controlling post-transcriptomic regulation during endurance exercise. PMID:26960911
Sarzynski, Mark A; Ghosh, Sujoy; Bouchard, Claude
Predicting the responsiveness to regular exercise is a topic of great relevance due to its potential role in personalized exercise medicine applications. The present review focuses on cardiorespiratory fitness (commonly measured by maximal oxygen uptake, V̇O2 max ), a trait with wide-ranging impact on health and performance indicators. Gains in V̇O2 max demonstrate large inter-individual variation even in response to standardized exercise training programmes. The estimated ΔVO2 max heritability of 47% suggests that genomic-based predictors alone are insufficient to account for the total trainability variance. Candidate gene and genome-wide linkage studies have not significantly contributed to our understanding of the molecular basis of trainability. A genome-wide association study suggested that V̇O2 max trainability is influenced by multiple genes of small effects, but these findings still await rigorous replication. Valuable evidence, however, has been obtained by combining skeletal muscle transcript abundance profiles with common DNA variants for the prediction of the V̇O2 max response to exercise training. Although the physiological determinants of V̇O2 max measured at a given time are largely enunciated, what is poorly understood are the details of tissue-specific molecular mechanisms that limit V̇O2 max and related signalling pathways in response to exercise training. Bioinformatics explorations based on thousands of variants have been used to interrogate pathways and systems instead of single variants and genes, and the main findings, along with those from exercise experimental studies, have been summarized here in a working model of V̇O2 max trainability.
Warburton, Darren E R; Haykowsky, Mark J; Quinney, H Arthur; Blackmore, Derrick; Teo, Koon K; Humen, Dennis P
Recent evidence indicates that endurance-trained athletes are able to increase their stroke volume (SV) throughout incremental upright exercise, probably due to a progressively greater effect of the Frank-Starling mechanism. This is contrary to the widely held belief that SV reaches a plateau at a submaximal heart rate (irrespective of fitness level), owing to a limitation in the time for diastolic filling. The purpose of this investigation was to evaluate whether endurance-trained athletes rely on a progressively greater effect of the Frank-Starling mechanism throughout incremental exercise. A secondary purpose was to evaluate the effects of postural position on the cardiovascular responses to incremental exercise. Ten male cyclists participated in this investigation. Left ventricular function was assessed throughout incremental exercise in the supine and upright positions (counterbalanced) using radionuclide ventriculography. Stroke volume increased in a linear fashion during incremental exercise in both the upright and supine positions. The increases in cardiac output (Q) throughout incremental to maximal exercise (in both the supine and upright positions) were significantly related to changes in heart rate, myocardial contractility and the Frank-Starling mechanism. Percentage changes in end-diastolic volume and SV were significantly greater in the upright position versus the supine position, reflecting an increased reliance on the Frank-Starling effect to increase Q. We conclude from this investigation that highly trained endurance athletes are able to make progressively increasing usage of the Frank-Starling effect throughout incremental exercise. Postural position has a significant effect on the relative contribution of heart rate, myocardial contractility and the Frank-Starling mechanism to the increase in Q during exercise conditions.
Sear, Joshua A; Hoare, Trent K; Scanlan, Aaron T; Abt, Grant A; Dascombe, Benjamin J
The current study investigated the effects of wearing whole-body compression garments (WBCGs) on prolonged high-intensity intermittent exercise (PHIIE) performance. Eight male team-sport athletes ([X +/- SD] 20.6 +/- 1.2 years; 72.9 +/- 5.9 kg; 57.5 +/- 3.7 ml.kg.min) completed a prescribed 45-minute PHIIE protocol on a nonmotorized treadmill in randomly assigned WBCG and control (typical soccer apparel) conditions. Subjects were given verbal and visual cues for movement categories, and they followed set target speeds, except when instructed of a variable run or sprint where the aim was to run as fast as possible. Total distance, velocity-specific distance, and high-intensity self-paced running speeds were taken as performance indicators. Heart rate, VO(2), tissue oxygenation index (TOI), and tissue hemoglobin index (nTHi) were continuously monitored across the protocol. Blood-lactate concentration ([BLa(-)]) was measured every 15 minutes. Magnitude-based inferences suggested that wearing WBCGs provided moderate strength likely improvements in total distance covered (5.42 +/- 0.63 vs. 5.88 +/- 0.64 km; 88:10:2%; and eta = 0.6) and low-intensity activity distance (4.21 +/- 0.51 vs. 4.56 +/- 0.57 km; 83:14:3%; and eta = 0.6) compared with the control. A similar likely increase was also observed in the average TOI of the WBCG condition (53.5 +/- 8.3% vs. 55.8 +/- 7.2%; 87:11:2%; and eta = 0.6). The current data demonstrated that wearing WBCGs likely increased physical performance, possibly because of improvements in muscle oxygenation and associated metabolic benefits. Therefore, wearing WBCGs during PHIIE may benefit the physical performance of team-sport athletes by likely metabolic changes within the muscle between high-intensity efforts.
Cathcart, Andrew J; Murgatroyd, Scott R; McNab, Alison; Whyte, Laura J; Easton, Chris
Laboratory-based studies have demonstrated that adding protein (PRO) to a carbohydrate (CHO) supplement can improve thermoregulatory capacity, exercise performance and recovery. However, no study has investigated these effects in a competitive sporting context. This study assessed the effects of combined CHO-PRO supplementation on physiological responses and exercise performance during 8 days of strenuous competition in a hot environment. Twenty-eight cyclists participating in the TransAlp mountain bike race were randomly assigned to fitness-matched placebo (PLA 76 g L(-1) CHO) or CHO-PRO (18 g L(-1) PRO, 72 g L(-1) CHO) groups. Participants were given enough supplements to allow ad libitum consumption. Physiological and anthropometric variables were recorded pre- and post-exercise. Body mass decreased significantly from race stage 1 to 8 in the PLA group (-0.75 ± 0.22 kg, P = 0.01) but did not change in the CHO-PRO group (0.42 ± 0.42 kg, P = 0.35). Creatine kinase concentration and muscle soreness were substantially elevated during the race, but were not different between groups (P = 0.82, P = 0.44, respectively). Urine osmolality was significantly higher in the CHO-PRO versus the PLA group (P = 0.04) and the rise in tympanic temperature from pre- to post-exercise was significantly less in CHO-PRO versus PLA (P = 0.01). The CHO-PRO group also completed the 8 stages significantly quicker than the PLA group (2,277 ± 127 vs. 2,592 ± 68 min, respectively, P = 0.02). CHO-PRO supplementation therefore appears to prevent body mass loss, enhance thermoregulatory capacity and improve competitive exercise performance despite no effect on muscle damage.
Le Guen, Marie; Chaté, Valérie; Hininger-Favier, Isabelle; Laillet, Brigitte; Morio, Béatrice; Pieroni, Gérard; Schlattner, Uwe; Pison, Christophe; Dubouchaud, Hervé
Decline in skeletal muscle mass and function starts during adulthood. Among the causes, modifications of the mitochondrial function could be of major importance. Polyunsaturated fatty (ω-3) acids have been shown to play a role in intracellular functions. We hypothesize that docosahexaenoic acid (DHA) supplementation could improve muscle mitochondrial function that could contribute to limit the early consequences of aging on adult muscle. Twelve-month-old male Wistar rats were fed a low-polyunsaturated fat diet and were given DHA (DHA group) or placebo (control group) for 9 wk. Rats from the DHA group showed a higher endurance capacity (+56%, P < 0.05) compared with control animals. Permeabilized myofibers from soleus muscle showed higher O2 consumptions (P < 0.05) in the DHA group compared with the control group, with glutamate-malate as substrates, both in basal conditions (i.e., state 2) and under maximal conditions (i.e., state 3, using ADP), along with a higher apparent Km for ADP (P < 0.05). Calcium retention capacity of isolated mitochondria was lower in DHA group compared with the control group (P < 0.05). Phospho-AMPK/AMPK ratio and PPARδ mRNA content were higher in the DHA group compared with the control group (P < 0.05). Results showed that DHA enhanced endurance capacity in adult animals, a beneficial effect potentially resulting from improvement in mitochondrial function, as suggested by our results on permeabilized fibers. DHA supplementation could be of potential interest for the muscle function in adults and for fighting the decline in exercise tolerance with age that could imply energy-sensing pathway, as suggested by changes in phospho-AMPK/AMPK ratio.
Belavý, Daniel L; Armbrecht, Gabriele; Gast, Ulf; Richardson, Carolyn A; Hides, Julie A; Felsenberg, Dieter
To evaluate the effect of short-duration, high-load resistive exercise, with and without whole body vibration on lumbar muscle size, intervertebral disk and spinal morphology changes, and low back pain (LBP) incidence during prolonged bed rest, 24 subjects underwent 60 days of head-down tilt bed rest and performed either resistive vibration exercise (n = 7), resistive exercise only (n = 8), or no exercise (n = 9; 2nd Berlin Bed-Rest Study). Discal and spinal shape was measured from sagittal plane magnetic resonance images. Cross-sectional areas (CSAs) of the multifidus, erector spinae, quadratus lumborum, and psoas were measured on para-axial magnetic resonance images. LBP incidence was assessed with questionnaires at regular intervals. The countermeasures reduced CSA loss in the multifidus, lumbar erector spinae and quadratus lumborum muscles, with greater increases in psoas muscle CSA seen in the countermeasure groups (P ≤ 0.004). There was little statistical evidence for an additional effect of whole body vibration above resistive exercise alone on these muscle changes. Exercise subjects reported LBP more frequently in the first week of bed rest, but this was only significant in resistive exercise only (P = 0.011 vs. control, resistive vibration exercise vs. control: P = 0.56). No effect of the countermeasures on changes in spinal morphology was seen (P ≥ 0.22). The results suggest that high-load resistive exercise, with or without whole body vibration, performed 3 days/wk can reduce lumbar muscle atrophy, but further countermeasure optimization is required.
Le Moyec, Laurence; Robert, Céline; Triba, Mohamed N; Billat, Véronique L; Mata, Xavier; Schibler, Laurent; Barrey, Eric
During long distance endurance races, horses undergo high physiological and metabolic stresses. The adaptation processes involve the modulation of the energetic pathways in order to meet the energy demand. The aims were to evaluate the effects of long endurance exercise on the plasma metabolomic profiles and to investigate the relationships with the individual horse performances. The metabolomic profiles of the horses were analyzed using the non-dedicated methodology, NMR spectroscopy and statistical multivariate analysis. The advantage of this method is to investigate several metabolomic pathways at the same time in a single sample. The plasmas were obtained before exercise (BE) and post exercise (PE) from 69 horses competing in three endurance races at national level (130-160 km). Biochemical assays were also performed on the samples taken at PE. The proton NMR spectra were compared using the supervised orthogonal projection on latent structure method according to several factors. Among these factors, the race location was not significant whereas the effect of the race exercise (sample BE vs PE of same horse) was highly discriminating. This result was confirmed by the projection of unpaired samples (only BE or PE sample of different horses). The metabolomic profiles proved that protein, energetic and lipid metabolisms as well as glycoproteins content are highly affected by the long endurance exercise. The BE samples from finisher horses could be discriminated according to the racing speed based on their metabolomic lipid content. The PE samples could be discriminated according to the horse ranking position at the end of the race with lactate as unique correlated metabolite. As a conclusion, the metabolomic profiles of plasmas taken before and after the race provided a better understanding of the high energy demand and protein catabolism pathway that could expose the horses to metabolic disorders.
Cappelli, Katia; Felicetti, Michela; Capomaccio, Stefano; Pieramati, Camillo; Silvestrelli, Maurizio; Verini-Supplizi, Andrea
Background The stress response is a critical factor in the training of equine athletes; it is important for performance and for protection of the animal against physio-pathological disorders. In this study, the molecular mechanisms involved in the response to acute and strenuous exercise were investigated using peripheral blood mononuclear cells (PBMCs). Results Quantitative real-time PCR (qRT-PCR) was used to detect modifications in transcription levels of the genes for matrix metalloproteinase-1 (MMP-1) and interleukin 8 (IL-8), which were derived from previous genome-wide expression analysis. Significant up-regulation of these two genes was found in 10 horses that had completed a race of 90–120 km in a time-course experimental design. Conclusion These results suggest that MMP-1 and IL-8 are both involved in the exercise-induced stress response, and this represents a starting point from which to understand the adaptive responses to this phenomenon. PMID:19552796
Olver, T Dylan; Laughlin, M Harold
Type 2 diabetes (T2D) alters capillary hemodynamics, causes capillary rarefaction in skeletal muscle, and alters endothelial and vascular smooth muscle cell phenotype, resulting in impaired vasodilatory responses. These changes contribute to altered blood flow responses to physiological stimuli, such as exercise and insulin secretion. T2D-induced microvascular dysfunction impairs glucose and insulin delivery to skeletal muscle (and other tissues such as skin and nervous), thereby reducing glucose uptake and perpetuating hyperglycemia and hyperinsulinemia. In patients with T2D, exercise training (EX) improves microvascular vasodilator and insulin signaling and attenuates capillary rarefaction in skeletal muscle. EX-induced changes subsequently augment glucose and insulin delivery as well as glucose uptake. If these adaptions occur in a sufficient amount of tissue, and skeletal muscle in particular, chronic exposure to hyperglycemia and hyperinsulinemia and the risk of microvascular complications in all vascular beds will decrease. We postulate that EX programs that engage as much skeletal muscle mass as possible and recruit as many muscle fibers within each muscle as possible will generate the greatest improvements in microvascular function, providing that the duration of the stimulus is sufficient. Primary improvements in microvascular function occur in tissues (skeletal muscle primarily) engaged during exercise, and secondary improvements in microvascular function throughout the body may result from improved blood glucose control. We propose that the added benefit of combined resistance and aerobic EX programs and of vigorous intensity EX programs is not simply "more is better." Rather, we believe the additional benefit is the result of EX-induced adaptations in and around more muscle fibers, resulting in more muscle mass and the associated microvasculature being changed. Thus, to acquire primary and secondary improvements in microvascular function and improved
Granados, Jorge; Gillum, Trevor L; Castillo, Weston; Christmas, Kevin M; Kuennen, Matthew R
A novel commercial training mask purportedly allows for combined respiratory muscle training and altitude exposure during exercise. We examined the mask's ability to deliver on this claim. Ten men completed three bouts of treadmill exercise at a matched workload (60%VO2peak) in a controlled laboratory environment. During exercise, the mask was worn in 2 manufacturer-defined settings (9,000 ft [9K] and 15,000 ft [15K]) and a Sham configuration (∼3,500 ft). Ventilation (V(E)), tidal volume (V(T)), respiratory rate (R(R)), expired oxygen (F(E)O2) and carbon dioxide (F(E)CO2), peripheral oxygen saturation (S(P)O2), heart rate, and RPE were measured each minute during exercise, and subjects completed the Beck Anxiety Inventory (BAI) immediately after. The mask caused a reduction in V(E) of ∼20 L/min in both the 9K and 15K configurations (p < 0.001). This was due to a reduction in R(R) of ∼10 b·min, but not V(T), which was elevated by ∼250 ml (p < 0.001). F(E)O2 was reduced and F(E)CO2 was elevated above Sham in both 9K and 15K (p < 0.001). VO2 was not different across conditions (p = 0.210), but VCO2 trended lower at 9K (p = 0.093) and was reduced at 15K (p = 0.016). V(E)/VO2 was 18.3% lower than Sham at 9K and 19.2% lower at 15K. V(E)/VCO2 was 16.2% lower than Sham at 9K and 18.8% lower at 15K (all p < 0.001). Heart rate increased with exercise (p < 0.001) but was not different among conditions (p = 0.285). S(P)O2 averaged 94% in Sham, 91% at 9K, and 89% at 15K (p < 0.001). RPE and BAI were also higher in 9K and 15K (p < 0.010), but there was no difference among mask conditions. The training mask caused inadequate hyperventilation that led to arterial hypoxemia and psychological discomfort, but the magnitude of these responses were small and they did not vary across mask configurations.
Rowlands, David S; Nelson, Andre R; Raymond, Frederic; Metairon, Sylviane; Mansourian, Robert; Clarke, Jim; Stellingwerff, Trent; Phillips, Stuart M
Protein-leucine supplement ingestion following strenuous endurance exercise accentuates skeletal-muscle protein synthesis and adaptive molecular responses, but the underlying transcriptome is uncharacterized. In a randomized single-blind triple-crossover design, 12 trained men completed 100 min of high-intensity cycling then ingested 70/15/180/30 g protein-leucine-carbohydrate-fat (15LEU), 23/5/180/30 g (5LEU), or 0/0/274/30 g (CON) beverages during the first 90 min of a 240 min recovery period. Vastus lateralis muscle samples (30 and 240 min postexercise) underwent transcriptome analysis by microarray followed by bioinformatic analysis. Gene expression was regulated by protein-leucine in a dose-dependent manner affecting the inflammatory response and muscle growth and development. At 30 min, 15LEU and 5LEU vs. CON activated transcriptome networks with gene-set functions involving cell-cycle arrest (Z-score 2.0-2.7, P < 0.01), leukocyte maturation (1.7, P = 0.007), cell viability (2.4, P = 0.005), promyogenic networks encompassing myocyte differentiation and myogenin (MYOD1, MYOG), and a proteinaceous extracellular matrix, adhesion, and development program correlated with plasma lysine, arginine, tyrosine, taurine, glutamic acid, and asparagine concentrations. High protein-leucine dose (15LEU-5LEU) activated an IL-1I-centered proinflammatory network and leukocyte migration, differentiation, and survival functions (2.0-2.6, <0.001). By 240 min, the protein-leucine transcriptome was anti-inflammatory and promyogenic (IL-6, NF- β, SMAD, STAT3 network inhibition), with overrepresented functions including decreased leukocyte migration and connective tissue development (-1.8-2.4, P < 0.01), increased apoptosis of myeloid and muscle cells (2.2-3.0, P < 0.002), and cell metabolism (2.0-2.4, P < 0.01). The analysis suggests protein-leucine ingestion modulates inflammatory-myogenic regenerative processes during skeletal muscle recovery from endurance exercise. Further
Laughlin, M. Harold
Type 2 diabetes (T2D) alters capillary hemodynamics, causes capillary rarefaction in skeletal muscle, and alters endothelial and vascular smooth muscle cell phenotype, resulting in impaired vasodilatory responses. These changes contribute to altered blood flow responses to physiological stimuli, such as exercise and insulin secretion. T2D-induced microvascular dysfunction impairs glucose and insulin delivery to skeletal muscle (and other tissues such as skin and nervous), thereby reducing glucose uptake and perpetuating hyperglycemia and hyperinsulinemia. In patients with T2D, exercise training (EX) improves microvascular vasodilator and insulin signaling and attenuates capillary rarefaction in skeletal muscle. EX-induced changes subsequently augment glucose and insulin delivery as well as glucose uptake. If these adaptions occur in a sufficient amount of tissue, and skeletal muscle in particular, chronic exposure to hyperglycemia and hyperinsulinemia and the risk of microvascular complications in all vascular beds will decrease. We postulate that EX programs that engage as much skeletal muscle mass as possible and recruit as many muscle fibers within each muscle as possible will generate the greatest improvements in microvascular function, providing that the duration of the stimulus is sufficient. Primary improvements in microvascular function occur in tissues (skeletal muscle primarily) engaged during exercise, and secondary improvements in microvascular function throughout the body may result from improved blood glucose control. We propose that the added benefit of combined resistance and aerobic EX programs and of vigorous intensity EX programs is not simply “more is better.” Rather, we believe the additional benefit is the result of EX-induced adaptations in and around more muscle fibers, resulting in more muscle mass and the associated microvasculature being changed. Thus, to acquire primary and secondary improvements in microvascular function and
Betts, James A; Williams, Clyde
This review considers aspects of the optimal nutritional strategy for recovery from prolonged moderate to high intensity exercise. Dietary carbohydrate represents a central component of post-exercise nutrition. Therefore, carbohydrate should be ingested as early as possible in the post-exercise period and at frequent (i.e. 15- to 30-minute) intervals throughout recovery to maximize the rate of muscle glycogen resynthesis. Solid and liquid carbohydrate supplements or whole foods can achieve this aim with equal effect but should be of high glycaemic index and ingested following the feeding schedule described above at a rate of at least 1 g/kg/h in order to rapidly and sufficiently increase both blood glucose and insulin concentrations throughout recovery. Adding ≥0.3 g/kg/h of protein to a carbohydrate supplement results in a synergistic increase in insulin secretion that can, in some circumstances, accelerate muscle glycogen resynthesis. Specifically, if carbohydrate has not been ingested in quantities sufficient to maximize the rate of muscle glycogen resynthesis, the inclusion of protein may at least partially compensate for the limited availability of ingested carbohydrate. Some studies have reported improved physical performance with ingestion of carbohydrate-protein mixtures, both during exercise and during recovery prior to a subsequent exercise test. While not all of the evidence supports these ergogenic benefits, there is clearly the potential for improved performance under certain conditions, e.g. if the additional protein increases the energy content of a supplement and/or the carbohydrate fraction is ingested at below the recommended rate. The underlying mechanism for such effects may be partly due to increased muscle glycogen resynthesis during recovery, although there is varied support for other factors such as an increased central drive to exercise, a blunting of exercise-induced muscle damage, altered metabolism during exercise subsequent to
Francescato, Maria Pia; Stel, Giuliana; Geat, Mario; Cauci, Sabina
Presently, no clear-cut guidelines are available to suggest the more appropriate physical activity for patients with type 1 diabetes mellitus due to paucity of experimental data obtained under patients' usual life conditions. Accordingly, we explored the oxidative stress levels associated with a prolonged moderate intensity, but fatiguing, exercise performed under usual therapy in patients with type 1 diabetes mellitus and matched healthy controls. Eight patients (4 men, 4 women; 49±11 years; Body Mass Index 25.0±3.2 kg·m(-2); HbA1c 57±10 mmol·mol(-1)) and 14 controls (8 men, 6 women; 47±11 years; Body Mass Index 24.3±3.3 kg·m(-2)) performed a 3-h walk at 30% of their heart rate reserve. Venous blood samples were obtained before and at the end of the exercise for clinical chemistry analysis and antioxidant capacity. Capillary blood samples were taken at the start and thereafter every 30 min to determine lipid peroxidation. Patients showed higher oxidative stress values as compared to controls (95.9±9.7 vs. 74.1±12.2 mg·L(-1) H2O2; p<0.001). In both groups, oxidative stress remained constant throughout the exercise (p = NS), while oxidative defence increased significantly at the end of exercise (p<0.02) from 1.16±0.13 to 1.19±0.10 mmol·L(-1) Trolox in patients and from 1.09±0.21 to 1.22±0.14 mmol·L(-1) Trolox in controls, without any significant difference between the two groups. Oxidative stress was positively correlated to HbA1c (p<0.005) and negatively related with uric acid (p<0.005). In conclusion, we were the first to evaluate the oxidative stress in patients with type 1 diabetes exercising under their usual life conditions (i.e. usual therapy and diet). Specifically, we found that the oxidative stress was not exacerbated due to a single bout of prolonged moderate intensity aerobic exercise, a condition simulating several outdoor leisure time physical activities. Oxidative defence increased in both patients and controls, suggesting
Hoffman, Martin D; Myers, Thomas M
Symptomatic exercise-associated hyponatremia (EAH) is known to be a potential complication from overhydration during exercise, but there remains a general belief that sodium supplementation will prevent EAH. We present a case in which a runner with a prior history of EAH consulted a sports nutritionist who advised him to consume considerable supplemental sodium, which did not prevent him from developing symptomatic EAH during a subsequent long run. Emergency medical services were requested for this runner shortly after he finished a 17-hr, 72-km run and hike in Grand Canyon National Park during which he reported having consumed 9.2-10.6 L of water and >6,500 mg of sodium. First responders determined his serum sodium concentration with point-of-care testing was 122 mEq/L. His hyponatremia was documented to have improved from field treatment with an oral hypertonic solution of 800 mg of sodium in 200 ml of water, and it improved further after significant aquaresis despite in-hospital treatment with isotonic fluids (lactated Ringer's). He was discharged about 5 hr after admission in good condition. This case demonstrates that while oral sodium supplementation does not necessarily prevent symptomatic EAH associated with overhydration, early recognition and field management with oral hypertonic saline in combination with fluid restriction can be effective treatment for mild EAH. There continues to be a lack of universal understanding of the underlying pathophysiology and appropriate hospital management of EAH.
Jeppesen, Jacob; Jordy, Andreas B.; Sjøberg, Kim A.; Füllekrug, Joachim; Stahl, Andreas; Nybo, Lars; Kiens, Bente
FATP1 and FATP4 appear to be important for the cellular uptake and handling of long chain fatty acids (LCFA). These findings were obtained from loss- or gain of function models. However, reports on FATP1 and FATP4 in human skeletal muscle are limited. Aerobic training enhances lipid oxidation; however, it is not known whether this involves up-regulation of FATP1 and FATP4 protein. Therefore, the aim of this project was to investigate FATP1 and FATP4 protein expression in the vastus lateralis muscle from healthy human individuals and to what extent FATP1 and FATP4 protein expression were affected by an increased fuel demand induced by exercise training. Eight young healthy males were recruited to the study. All subjects were non smokers and did not participate in regular physical activity (<1 time per week for the past 6 months, VO2peak 3.4±0.1 l O2 min−1). Subjects underwent an 8 week supervised aerobic training program. Training induced an increase in VO2peak from 3.4±0.1 to 3.9±0.1 l min−1 and citrate synthase activity was increased from 53.7±2.5 to 80.8±3.7 µmol g−1 min−1. The protein content of FATP4 was increased by 33%, whereas FATP1 protein content was reduced by 20%. Interestingly, at the end of the training intervention a significant association (r2 = 0.74) between the observed increase in skeletal muscle FATP4 protein expression and lipid oxidation during a 120 min endurance exercise test was observed. In conclusion, based on the present findings it is suggested that FATP1 and FATP4 proteins perform different functional roles in handling LCFA in skeletal muscle with FATP4 apparently more important as a lipid transport protein directing lipids for lipid oxidation. PMID:22235293
Radaelli, Regis; Fleck, Steven J; Leite, Thalita; Leite, Richard D; Pinto, Ronei S; Fernandes, Liliam; Simão, Roberto
The study's purpose was to compare the response of performing 1, 3, and 5 sets on measures of performance and muscle hypertrophy. Forty-eight men, with no weight training experience, were randomly assigned to one of the 3 training groups, 1 SET, 3 SETS, 5 SETS, or control group. All training groups performed 3 resistance training sessions per week for 6 months. The 5 repetition maximum (RM) for all training groups increased in the bench press (BP), front lat pull down (LPD), shoulder press (SP), and leg press (LP) (p ≤ 0.05), with the 5 RM increases in the BP and LPD being significantly greater for 5 SETS compared with the other training groups (p ≤ 0.05). Bench press 20 RM in the 3-SET and 5-SET groups significantly increased with the increase being significantly greater than the 1-SET group and the 5-SET group increase being significantly greater than the 3-SET group (p ≤ 0.05). LP 20 RM increased in all training groups (p ≤ 0.05), with the 5-SETS group showing a significantly greater increase than the 1-SET group (p ≤ 0.05). The 3-SET and 5-SET groups significantly increased elbow flexor muscle thickness (MT) with the 5-SET increase being significantly greater than the other 2 training groups (p ≤ 0.05). The 5-SET group significantly increased elbow extensor MT with the increase being significantly greater than the other training groups (p ≤ 0.05). All training groups decreased percent body fat, increased fat-free mass, and vertical jump ability (p ≤ 0.05), with no differences between groups. The results demonstrate a dose-response for the number of sets per exercise and a superiority of multiple sets compared with a single set per exercise for strength gains, muscle endurance, and upper arm muscle hypertrophy.
Barone, Rosario; Macaluso, Filippo; Catanese, Patrizia; Marino Gammazza, Antonella; Rizzuto, Luigi; Marozzi, Paola; Lo Giudice, Giuseppe; Stampone, Tomaso; Cappello, Francesco; Morici, Giuseppe; Zummo, Giovanni; Farina, Felicia; Di Felice, Valentina
A new role for fat supplements, in particular conjugated linoleic acid (CLA), has been delineated in steroidogenesis, although the underlying molecular mechanisms have not yet been elucidated. The aims of the present study were to identify the pathway stimulated by CLA supplementation using a cell culture model and to determine whether this same pathway is also stimulated in vivo by CLA supplementation associated with exercise. In vitro, Leydig tumour rat cells (R2C) supplemented with different concentrations of CLA exhibited increasing testosterone biosynthesis accompanied by increasing levels of CYP17A1 mRNA and protein. In vivo, trained mice showed an increase in free plasma testosterone and an up-regulation of CYP17A1 mRNA and protein. The effect of training on CYP17A1 expression and testosterone biosynthesis was significantly higher in the trained mice supplemented with CLA compared to the placebo. The results of the present study demonstrated that CLA stimulates testosterone biosynthesis via CYP17A1, and endurance training led to the synthesis of testosterone in vivo by inducing the overexpression of CYP17A1 mRNA and protein in the Leydig cells of the testis. This effect was enhanced by CLA supplementation. Therefore, CLA-associated physical activity may be used for its steroidogenic property in different fields, such as alimentary industry, human reproductive medicine, sport science, and anti-muscle wasting.
Peltier, Sébastien L; Leprêtre, Pierre-Marie; Metz, Lore; Ennequin, Gael; Aubineau, Nicolas; Lescuyer, Jean-François; Duclos, Martine; Brink, Thibault; Sirvent, Pascal
Sports drinks are often used before, during, and after tennis tournaments, but their ability to influence physiological and psychological variables and the characteristics of tennis match play remains uncertain. The objective of this study was to evaluate the impact of ingesting specially formulated pre-exercise, endurance, and recovery sports drinks on glycemia and performance indices during a simulated tennis tournament. Eight well-trained male tennis players performed two 3-match round-robin tennis tournaments although ingesting sports drinks (SPDs) or placebos (PLAs) before, during, and after each match (crossover study design). Before the first tournament, match and drink order were randomized (SPDs or PLAs first) and players were placed under controlled nutritional and hydration conditions. Glycemia, heart rate response, rate of perceived exertion, and notational/match analysis were assessed during each match. Sports drinks maintained higher glycemia levels during match 2 and 3 of the tennis tournament compared with PLAs (p < 0.01). Moreover, higher mean heart rates (p < 0.01) and stroke frequencies (p < 0.01) concomitantly with lower rates of perceived exertion (p < 0.01) were recorded throughout the duration of the tournament, when players used the SPDs. During a 3-match tennis tournament, SPDs allow higher stroke frequency during play, with decreased rates of perceived exertion.
Shipov, Anna; Sharir, Amnon; Zelzer, Elazar; Milgram, Joshua; Monsonego-Ornan, Efrat; Shahar, Ron
Many studies have described the effects of exercise restriction on the mammalian skeleton. In particular, human and animal models have shown that reduction in weight bearing leads to generalised bone loss and deterioration of its mechanical properties. The aim of this study was to assess the effect of prolonged exercise restriction coupled with heavy calcium demands on the micro-structural, compositional and mechanical properties of the avian skeleton. The tibiae and humeri of 2-year-old laying hens housed in conventional caging (CC) and free-range (FR) housing systems were compared by mechanical testing and micro-computed tomography (microCT) scanning. Analyses of cortical, cancellous and medullary bone were performed. Mechanical testing revealed that the tibiae and humeri of birds from the FR group had superior mechanical properties relative to those of the CC group, and microCT scanning indicated larger cortical and lower medullary regions in FR group bones. Cancellous bone analysis revealed higher trabecular thickness and a higher bone volume fraction in the FR group, but no difference in mineral density. The biomechanical superiority of bones from the FR group was primarily due to structural rather than compositional differences, and this was reflected in both the cortical and cancellous components of the bones. The study demonstrated that prolonged exercise restriction in laying hens resulted in major structural and mechanical effects on the bird skeleton.
Ploughman, M; Granter-Button, S; Chernenko, G; Tucker, B A; Mearow, K M; Corbett, D
The optimal amount of endurance exercise required to elevate proteins involved in neuroplasticity during stroke rehabilitation is not known. This study compared the effects of varying intensities and durations of endurance exercise using both motorized and voluntary running wheels after endothelin-I-induced focal ischemia in rats. Hippocampal levels of brain-derived neurotrophic factor, insulin-like growth factor I and synapsin-I were elevated in the ischemic hemisphere even in sedentary animals suggesting an intrinsic restorative response 2 weeks after ischemia. In the sensorimotor cortex and the hippocampus of the intact hemisphere, one episode of moderate walking exercise, but not more intense running, resulted in the greatest increases in levels of brain-derived neurotrophic factor and synapsin-I. Exercise did not increase brain-derived neurotrophic factor, insulin-like growth factor I or synapsin-I in the ischemic hemisphere. In voluntary running animals, both brain and serum insulin-like growth factor I appeared to be intensity dependent and were associated with decreasing serum levels of insulin-like growth factor I and increasing hippocampal levels of insulin-like growth factor I in the ischemic hemisphere. This supports the notion that exercise facilitates the movement of insulin-like growth factor I across the blood-brain barrier. Serum corticosterone levels were elevated by all exercise regimens and were highest in rats exposed to motorized running of greater speed or duration. The elevation of corticosterone did not seem to alter the expression of the proteins measured, however, graduated exercise protocols may be indicated early after stroke. These findings suggest that relatively modest exercise intervention can increase proteins involved in synaptic plasticity in areas of the brain that likely subserve motor relearning after stroke.
Davis, Greggory R; Etheredge, Corey E; Marcus, Lena; Bellar, David
The purpose of this study was to examine tympanic temperature, melatonin, and cognitive function during a 36-hour endurance event. Nine male and three female participants took part in a 36-hour sustained endurance event without sleep (N = 12, mean age = 31.8 ± 5.0 yrs). Participants were stopped for data collection at checkpoints throughout the 36-hour event. Tympanic temperature was assessed, a psychomotor vigilance test (PVT) was administered, and saliva samples were collected. Salivary melatonin was determined via immunoassay. During the 36 hours of competition, melatonin levels were negatively correlated with the day of the race (rs = -0.277, P = 0.039) and positively associated with nighttime (rs = 0.316, P = 0.021). Significant main effects of tympanic temperature (P < 0.001), day of the competition (P = 0.018), and a tympanic temperature ∗ day of competition interaction (P < 0.001) were used to predict minor lapses in attention. No associations between melatonin levels and cognitive function were observed (P > 0.05). During the event tympanic temperature declined and was associated with an increase in lapses in attention. With sustained endurance events becoming more popular future research is warranted to evaluate the physiological impact of participation.
Soare, Andreea; Cangemi, Roberto; Omodei, Daniela; Holloszy, John O; Fontana, Luigi
Reduction of body temperature has been proposed to contribute to the increased lifespan in calorie restricted animals and mice overexpressing the uncoupling protein-2 in hypocretin neurons. However, nothing is known regarding the long-term effects of calorie restriction (CR) with adequate nutrition on body temperature in humans. In this study, 24-hour core body temperature was measured every minute by using ingested telemetric capsules in 24 men and women (mean age 53.7 ± 9.4 yrs) consuming a CR diet for an average of 6 years, 24 age- and sex-matched sedentary (WD) and 24 body fat-matched exercise-trained (EX) volunteers, who were eating Western diets. The CR and EX groups were significantly leaner than the WD group. Energy intake was lower in the CR group (1769 ± 348 kcal/d) than in the WD (2302 ± 668 kcal/d) and EX (2798 ± 760 kcal/d) groups (P < 0.0001). Mean 24-hour, day-time and night-time core body temperatures were all significantly lower in the CR group than in the WD and EX groups (P ≤ 0.01). Long-term CR with adequate nutrition in lean and weight-stable healthy humans is associated with a sustained reduction in core body temperature, similar to that found in CR rodents and monkeys. This adaptation is likely due to CR itself, rather than to leanness, and may be involved in slowing the rate of aging.
Melton, S A; Keenan, M J; Stanciu, C E; Hegsted, M; Zablah-Pimentel, E M; O'Neil, C E; Gaynor, P; Schaffhauser, A; Owen, K; Prisby, R D; LaMotte, L L; Fernandez, J M
In this five-week study, we tested the hypotheses that free access to a maintenance diet supplemented with L-carnitine (L-C) would reduce body fat in adult, sedentary, ovariectomized (OVX) rats, and that there would be an additive effect of L-C on weight reduction in swim-trained animals. As expected, serum carnitine was higher in rats fed the L-C diet, and the OVX-induced weight gain and abdominal fat were counteracted by swimming. L-C supplementation did not reduce the weight gain or abdominal fat in these adult female rats, Moreover, though not reaching statistical significance, rats that were fed L-C demonstrated a tendency for greater weight gain than their basal-fed counterparts despite no difference in energy intake. If the results of this study on ovariectomized rats can be translated to postmenopausal women, moderate intensity exercise may be recommended, but L-C supplementation, with no energy restriction, may be contraindicated as a weight loss method in this cohort.
Krüger, K; Bredehöft, J; Mooren, F C; Rummel, C
Acute endurance exercise has been shown to modulate cyclooxygenase (COX)-2 expression, which is suggested to affect neuronal plasticity and learning. Here, we investigated the effect of regular strength and endurance training on cerebral COX-2 expression, inflammatory markers in the brain, and circulating cytokines. Male C57BL/6N mice were assigned to either a sedentary control group (CG), an endurance training group (EG; treadmill running for 30 min/day, 5 times/wk, 10 wk), or a strength training group (SG; strength training by isometric holding, same duration as EG). Four days after the last bout of exercise, blood and brain were collected and analyzed using real-time PCR, Western blot, and a multiplexed immunoassay. In EG, COX-2 mRNA expression in the cortex/hippocampus increased compared with CG. A significant increase of COX-2 protein levels was observed in both cortex/hippocampus and hypothalamus of mice from the SG. Nuclear factor (NF)κB protein levels were significantly increased in mice from both exercise groups (hypothalamus). A significant increase in the expression of microsomal prostaglandin E synthase (mPGES), an enzyme downstream of COX-2, was found in the hypothalamus of both the EG and SG. While most inflammatory factors, like IL-1α, IL-18, and IL-2, decreased after training, a positive association was found between COX-2 mRNA expression (cortex/hippocampus) and plasma IL-6 in the EG. Taken together, this study demonstrates that both endurance as well as strength training induces COX-2 expression in the cortex/hippocampus and hypothalamus of mice. A potential mediator of COX-2 expression after training might be circulating interleukin (IL)-6. However, further research is necessary to elucidate the role of inflammatory pathways on brain plasticity after training.
AC and CY exercise for any of the diff RPE. Local RPE was generally higher than central RPE. Selected physiological responses accounted for more... physiological responses was much higher for arm crank than cycle exercise for W7 T-7 7’v* 7 7. 7 77 7 9 w2 all differentiated RPE contrasts (ABS and REL-AC...total accountable variance from these selected physiological responses was greater for arm crank (median R2 = 0.99) than cycle exercise (median R 2 = 0.75
Platts, Steven H.; Stenger, Michael B.; Ploutz-Snyder, Lori L.; Lee, Stuart M. C.
Approximately 20% of Space Shuttle astronauts became presyncopal during operational stand and 80deg head-up tilt tests, and the prevalence of orthostatic intolerance increases after longer missions. Greater than 60% of the US astronauts participating in Mir and early International Space Station missions experienced presyncope during post-flight tilt tests, perhaps related to limitations of the exercise hardware that prevented high intensity exercise training until later ISS missions. The objective of this study was to determine whether an intense resistive and aerobic exercise countermeasure program designed to prevent cardiovascular and musculoskeletal deconditioning during 70 d of bed rest (BR), a space flight analog, would protect against post-BR orthostatic intolerance. METHODS Twenty-six subjects were randomly assigned to one of three groups: non-exercise controls (n=11) or one of two exercise groups (ExA, n=8; ExB, n=7). Both ExA and ExB groups performed the same resistive and aerobic exercise countermeasures during BR, but one exercise group received testosterone supplementation while the other received a placebo during BR in a double-blinded fashion. On 3 d/wk, subjects performed lower body resistive exercise and 30 min of continuous aerobic exercise (=75% max heart rate). On the other 3 d/wk, subjects performed only highintensity, interval-style aerobic exercise. Orthostatic intolerance was assessed using a 15-min 80? head-up tilt test performed 2 d (BR-2) before and on the last day of BR (BR70). Plasma volume was measured using carbon monoxide rebreathing on BR-3 and before rising on the first recovery day (BR+0). The code for the exercise groups has not been broken, and results are reported here without group identification. RESULTS Only one subject became presyncopal during tilt testing on BR-2, but 7 of 11 (63%) controls, 3 of 8 (38%) ExA, and 4 of 7 (57%) ExB subjects were presyncopal on BR70. Survival analysis of post-BR tilt tests revealed no
Endurance exercise training induces an increase in the respiratory capacity of muscle, resulting in an increased capacity to generate ATP as well as improved efficiency of muscle contraction. Such adaptations are largely the result of a coordinated genetic response that increases mitochondrial proteins, fatty acid oxidation enzymes and the exercise- and insulin-stimulated glucose transporter GLUT4, and shifts the contractile and regulatory proteins to their more efficient isoforms. In recent years a number of the transcriptional regulators involved in this genetic response have been identified and these factors can be classified into two different groups. The first group comprises transcription factors such as nuclear respiratory factors (NRF) 1 and 2 and PPAR alpha that bind DNA in a sequence-specific manner. The second group, referred to as transcriptional co-activators, alter transcription without directly binding to DNA. The PPAR gamma co-activator (PGC) family of proteins have been identified as the central family of transcriptional co-activators for induction of mitochondrial biogenesis. PGC-1 alpha is activated by exercise, and is sufficient to produce the endurance phenotype through direct interactions with NRF-1 and PPAR alpha, and potentially NRF-2. Furthering the understanding of the activation of PGC proteins following exercise has implications beyond improving athletic performance, including the possibility of providing targets for the treatment of frailty in the elderly, obesity and diseases such as mitochondrial myopathies and diabetes.
Pokora, Ilona; Żebrowska, Aleksandra
The study evaluated differences in response to exercise stress between endurance and high-intensity intermittent trained athletes in a thermoneutral environment using a physiological strain index (PSI). Thirty-two subjects participated in a running exercise under normal (23°C, 50% RH) conditions. The group included nine endurance trained athletes (middle-distance runners - MD), twelve high-intensity intermittent trained athletes (soccer players - HIIT) and eleven students who constituted a control group. The exercise started at a speed of 4 km·h(-1) which was increased every 3 min by 2 km·h(-1) to volitional exhaustion. The heart rate was recorded with a heart rate monitor and aural canal temperature was measured using an aural canal temperature probe. The physiological strain index (PSI) and the contribution of the circulatory and thermal components to the overall physiological strain were calculated from the heart rate and aural canal temperature. The physiological strain index differed between the study and control participants, but not between the MD and HIIT groups. The physiological strain in response to exercise stress in a thermoneutral environment was mainly determined based on the circulatory strain (MD group - 73%, HIIT group - 70%). The contribution of the circulatory and thermal components to the physiological strain did not differ significantly between the trained groups (MD and HIIT) despite important differences in morphological characteristics and training-induced systemic cardiovascular and thermoregulatory adaptations.
O'Keefe, James H; Lavie, Carl J; Guazzi, Marco
The question is not whether exercise is or isn't one of the very best strategies for improving quality of life, cardiovascular (CV) health and longevity-it is. And there is no debate as to whether or not strenuous high-intensity endurance training produces an amazingly efficient, compliant, and powerful pump-it does. The essence of the controversy centers on what exactly is the ideal pattern of long-term physical activity (PA) for conferring robust and enduring CV health, while also optimizing life expectancy. With that goal in mind, this review will focus on the question: "Is more always better when it comes to exercise?" And if a dose-response curve exists for the therapeutic effects of PA, where is the upper threshold at which point further training begins to detract from the health and longevity benefits noted with moderate exercise? The emerging picture from the cumulative data on this hotly debated topic is that moderate exercise appears to be the sweet spot for bestowing lasting CV health and longevity. However, the specific definition of moderate in this context is not clear yet.
Azad, Ahmad; Ghasemi, Fatemeh; Rahmani, Ahmad
Background: It is well known that exercise training has positive effect on catecholamine response to a given work load. But in this regard, the effective method of training needs to be studied. Objectives: The aim of this study was to compare the effects of 8 weeks endurance exercise with two overloading patterns on the left ventricular catecholamine levels. Materials and Methods: 29 male Wistar rats were randomly assigned to control (n = 9), daily sinusoidal overloading (n = 10) and weekly sinusoidal overloading (n = 10) groups. After the last exercise session, left ventricular blood samples were obtained immediately after lactate threshold test. Plasma concentrations of adrenaline and noradrenaline were measured by ELISA method. One way analysis of variance was used for analysis of the data. Results: Immediately after lactate threshold test, adrenaline level was significantly (P < 0.05) lower in weekly loading group than in control and daily loading groups. Adrenaline was higher in the daily loading group compared with control group but did not reach the significant level. Noradrenaline levels were not significantly (P > 0.05) different between three study groups. Conclusions: The results showed 8 weeks of endurance exercise with weekly sinusoidal overloading pattern could induce a lower adrenal medulla activity (reflection of physical and physiological improvement) than daily sinusoidal loading pattern in response to the same absolute work load. PMID:26715962
Hyatt, Hayden W; Smuder, Ashley J; Sollanek, Kurt J; Morton, Aaron B; Roberts, Michael D; Kavazis, Andreas N
The aim of this study was to evaluate exercise-induced transcriptional and protein responses of heart, soleus (slow oxidative), and plantaris (fast glycolytic) muscle in response to ten days of endurance exercise training. Four-month old female Sprague-Dawley rats were assigned to either a sedentary (SED) or endurance exercise-training (EXE) group (n=8 per group). The heart, plantaris, and soleus were excised and used for biochemical analyses. Our results show that heart and plantaris from EXE animals had higher protein levels of superoxide dismutase 2 (SOD2) compared to SED animals (P<0.05). Also, the protein levels of catalase were higher in plantaris of EXE animals compared to SED animals (P<0.05). No significant differences existed for 4 hydroxynonenal (4HNE) conjugated proteins (index of oxidative damage) in the three tissues between SED and EXE animals. mRNA levels of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) were higher in plantaris of EXE animals compared to SED animals (P<0.05), and mRNA levels of estrogen-related receptor alpha (ERRα) were lower in the heart of EXE animals compared to SED animals. In conclusion, heart and plantaris are responsive to ten days of treadmill training, while greater exercise intensities or durations may be needed to elicit alterations in soleus. PMID:28078055
Abstract The study evaluated differences in response to exercise stress between endurance and high-intensity intermittent trained athletes in a thermoneutral environment using a physiological strain index (PSI). Thirty-two subjects participated in a running exercise under normal (23°C, 50% RH) conditions. The group included nine endurance trained athletes (middle-distance runners - MD), twelve high-intensity intermittent trained athletes (soccer players - HIIT) and eleven students who constituted a control group. The exercise started at a speed of 4 km·h–1 which was increased every 3 min by 2 km·h–1 to volitional exhaustion. The heart rate was recorded with a heart rate monitor and aural canal temperature was measured using an aural canal temperature probe. The physiological strain index (PSI) and the contribution of the circulatory and thermal components to the overall physiological strain were calculated from the heart rate and aural canal temperature. The physiological strain index differed between the study and control participants, but not between the MD and HIIT groups. The physiological strain in response to exercise stress in a thermoneutral environment was mainly determined based on the circulatory strain (MD group - 73%, HIIT group – 70%). The contribution of the circulatory and thermal components to the physiological strain did not differ significantly between the trained groups (MD and HIIT) despite important differences in morphological characteristics and training-induced systemic cardiovascular and thermoregulatory adaptations. PMID:28149347
Nazar, K.; Greenleaf, J. E.; Philpott, D.; Pohoska, E.; Olszewska, K.; Kaciuba-Uscilko, H.
The effect of exhaustive treadmill exercise on mitochondrial density (MD) and ultrastructural changes in quadriceps femoris muscle was studied in 7 normal, healthy, male mongrel dogs before and after restricted activity (RA) and following a subsequent 2-month exercise retraining period. Mean time to exhaustion in the 2-month group decreased from 177 +/- 11 min before to 90 +/- 16 min after RA; retraining increased tolerance to 219 +/- 36 min above the pre-RA and 143 percent above the post-RA time. Post-RA exhaustion time in the 5-months group was 25 and 45 min. Muscle samples taken after RA showed abnormalities indicative of degeneration, which were reversed by retraining. Resting MD decreased from a control level of 27.8 percent to 14.7 percent and 16.3 percent, and was restored to 27.1 percent after retraining. Exhaustive exercise caused an increase in MD under control conditions and after RA, but not following retraining. Disruption of mitochondria after exercise was evident after 5-month confinement. Factors causing mitochondrial changes and eventually their disruption during exercise after restricted activity are not related as much to the state of fatigue as to the pre-exercise quality of the muscle modified by disease or training.
Vercruyssen, Fabrice; Easthope, Christopher; Bernard, Thierry; Hausswirth, Christophe; Bieuzen, Francois; Gruet, Mathieu; Brisswalter, Jeanick
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.
Caillaud, Corinne; Connes, Philippe; Ben Saad, Helmi; Mercier, Jacques
Animal studies have suggested that erythropoietin, besides its well-known hematopoietic effects, can modulate metabolism and prevent fat accumulation. We investigated the effects of repeated injections of recombinant human erythropoietin (EPO) on the balance of substrate oxidation during aerobic exercise in humans. Twelve healthy aerobically trained males received subcutaneously either moderate dose of EPO (50 U/kg, EPO) or saline injections (NaCl 0.9 %, control) three times a week for 4 weeks. Body weight, % fat, maximal aerobic capacity, and substrate utilization during exercise were assessed before and after treatment, while hemoglobin and hematocrit were monitored regularly during the treatment. Carbohydrate and fat oxidation were evaluated via indirect calorimetry, during a submaximal exercise performed at 75 % of the participants' maximal aerobic capacity (V̇(O2max)) for 60 min. Results showed that 4 weeks of EPO treatment significantly enhanced fat oxidation (+56 % in EPO versus -9 % in control) during exercise, independent of its effects on hematological parameters or V̇(O2max). This study shows that EPO can modulate substrate utilization during exercise, leading to enhanced fat utilization and lower use of carbohydrates. This opens new research directions exploring whether systemic EPO levels, in physiological conditions, participate to the modulation of fat oxidation.
Gozansky, Wendolyn S.; Barry, Daniel W.; MacLean, Paul S.; Grunwald, Gary K.; Hill, James O.
Fat oxidation during exercise is increased by endurance training, and evidence suggests that fat oxidation during exercise is impaired in obesity. Thus the primary aim of this study was to compare the acute effects of exercise on 24-h fat oxidation and fat balance in lean sedentary [LS, n = 10, body mass index (BMI) = 22.5 ± 6.5 kg/m2], lean endurance-trained (LT, n = 10, BMI = 21.2 ± 1.2 kg/m2), and obese sedentary (OS, n = 7, BMI = 35.5 ± 4.4 kg/m2) men and women. Twenty-four-hour energy expenditure and substrate oxidation were measured under sedentary (control; CON) and exercise (EX) conditions while maintaining energy balance. During EX, subjects performed 1 h of stationary cycling at 55% of aerobic capacity. Twenty-four-hour fat oxidation did not differ on the CON or EX day in LS (43 ± 9 vs. 29 ± 7 g/day, respectively), LT (53 ± 8 vs. 42 ± 5 g/day), or OS (58 ± 7 vs. 80 ± 9 g/day). However, 24-h fat balance was significantly more positive on EX compared with CON (P < 0.01). Twenty-four-hour glucose, insulin, and free fatty acid (FFA) profiles were similar on the EX and CON days, but after consumption of the first meal, FFA concentrations remained below fasting levels for the remainder of the day. These data suggest that when exercise is performed with energy replacement (i.e., energy balance is maintained), 24-h fat oxidation does not increase and in fact, may be slightly decreased. It appears that the state of energy balance is an underappreciated factor determining the impact of exercise on fat oxidation. PMID:19833807
König, D; Bissé, E; Deibert, P; Müller, H-M; Wieland, H; Berg, A
The interrelation between physical exercise and plasma levels of homocysteine (Hcy), vitamin B(12), and folic acid has not been examined. Therefore, we investigated the influence of extensive endurance training and acute intense exercise on plasma concentrations of total Hcy, vitamin B(12), and folic acid in 42 well-trained male triathletes. Examinations and blood sampling took place before and after a 30-day endurance training period as well as before and 1 and 24 h after a competitive exercise (sprint triathlon). Following the training period, no significant change in Hcy levels could be detected for the whole group. Subgroup analysis in quartiles of training volume revealed that - as compared with the lowest quartile (low-training group: 9.1 h training/week) - athletes in the highest training quartile (high-training group: 14.9 h training/week) exhibited a significant decrease in Hcy levels (from 12.7 +/- 2.3 to 11.7 +/- 2.4 micromol/l as compared with levels of 12.5 +/- 1.5 and 12.86 +/- 1.5 micromol/l in the low-training group; p < 0.05). The plasma folate levels were significantly higher in the high-training group at all points of examination (p < 0.05). 1 h and 24 h after competition, the Hcy concentration increased in all athletes independent of the previous training volume (24 h: 12.3 +/- 1.8 vs. 13.5 +/- 2.6 micromol/l; p < 0.001), although the increase was decisively stronger in the low-training group. 1 h after competition, the plasma folate concentration increased (7.03 +/- 2.1 vs. 8.33 +/- 2.1 ng/ml; p < 0.05) in all athletes. Multivariate analysis showed that the exercise-induced increase in the Hcy levels was dependent on baselines levels of folate and training volume, but not on the vitamin B(12) levels. In conclusion, although intense exercise acutely increased the Hcy levels, chronic endurance exercise was not associated with higher Hcy concentrations. Moreover, athletes with the highest training volume, exhibiting also the highest plasma folate
Park, J H; Brown, R L; Park, C R; Cohn, M; Chance, B
The purpose of this study was to investigate whether genetically determined properties of muscle metabolism contribute to the exceptional physical endurance of world-class distance runners. ATP, phosphocreatine, inorganic phosphate, and pH were quantitatively determined by 31P nuclear magnetic resonance spectroscopy in the wrist flexor muscles of elite long-distance runners and sedentary control subjects. These muscles had not been exposed to any specific program of exercise training in either group of subjects. The "untrained" muscles were examined at rest, during two cycles of three grades of exercise, and in recovery. The flexor muscles of the athletes had higher concentrations of phosphocreatine and ATP than did those of the control subjects at rest and during exercise. The athletes' muscles possessed a higher capacity for generation of ATP by oxidative metabolism than did control subjects' muscles according to the following criteria: (i) high force output, 60% of maximum voluntary contraction, was more easily reached and better maintained in both exercise cycles; (ii) the ratio of inorganic phosphate to phosphocreatine rose less during exercise and recovered faster in the postexercise period; (iii) there was no loss of adenine nucleotides or total phosphate from the athletes' muscles but significant losses from the control subjects' muscles; and (iv) the pH decreased no more than 0.1 unit in the athletes' muscles during exercise, attesting to a relatively slow glycolysis and/or a rapid oxidation of lactate. In the muscles of the control subjects, on the other hand, the pH decreased nearly 0.4 unit early in the first exercise cycle, indicating a relatively fast glycolysis and/or slower oxidation of lactate. In the second exercise cycle, the pH returned to near normal in the control subjects' muscles, reflecting diminished lactate formation because of glycogen depletion and lactate washout by the high blood flow induced by exercise. By the end of the exercise
Gimenez, M; Servera, E; Salinas, W
A new 45 min Square-Wave Endurance Exercise Test (SWEET) performed on a cycle ergometer and designed for endurance training was studied in 43 normal subjects: Untrained (U), twelve women and seven men and Trained (T), eight women and 16 men. Among them seven were elite sportsmen (E). Preliminary measurements were made of VO2 max by constant power and Maximal Tolerated Power (MTP) in a progressive test (+ 30 W/3 min). To the SWEET's base, established as a % of individual MTP, a peak of 1 min at MTP was added every 5 minutes. Maximum Intensity of Endurance during the SWEET (MIE45) is defined by both maximal heart rate (HR) at the end of the test and the impossibility of maintaining 5% above the percent MTP of the MIE45 for 45 min. Exhaustion was reached at the end of the MIE45, which could be expressed as % MTP, as total energy expenditure (TEE) in liters of O2, or as total mechanical work (TMW) in kiloJoules per kg of weight (kJ . kg-1). VE, VCO2, VO2 and HR were continuously measured. VO2 max, TMW and % MTP were significantly higher in T than in U subjects. The E subjects show the highest values of those parameters. TMW and TEE were well correlated (r = 0.992, p less than 0.001, n = 43) indicating good efficiency. TMW in T (r = 0.453) and in E men (r = 0.442) were however less well correlated to the VO2 max. MIE45 therefore gives different information in the evaluation of "endurance capacity" at the time of measurement than that provided by VO2 max. Because of the high TEE per session it could be useful for endurance training of T and U subjects.
Chan, Val; Duffield, Rob; Watsford, Mark
This study investigated the effects of wearing compression garments during and 24 h following a 4-h exercise protocol simulating manual-labour tasks. Ten physically trained male participants, familiar with labouring activities, undertook 4 h of work tasks characteristic of industrial workplaces. Participants completed 2 testing sessions, separated by at least 1 week. In the experimental condition, participants wore a full-length compression top and compression shorts during the exercise protocol and overnight recovery, with normal work clothes worn in the control condition. Testing for serum creatine kinase and C-reactive protein, handgrip strength, knee flexion and extension torque, muscle stiffness, perceived muscle soreness and fatigue as well as heart rate and rating of perceived exertion (RPE) responses to 4-min cycling were performed before, following, and 24 h after exercise. Creatine kinase, muscle soreness, and rating of perceived fatigue increased following the exercise protocol (p < 0.05) as did RPE to a standardised cycling warm-up bout. Conversely, no postexercise changes were observed in C-reactive protein, handgrip strength, peak knee flexion torque, or stiffness measures (p > 0.05). Knee extension torque was significantly higher in the control condition at 24 h postexercise (3.1% ± 5.4% change; compression: 2.2% ± 11.1% change), although no other variables were different between conditions at any time. However, compression demonstrated a moderate-large effect (d > 0.60) to reduce perceived muscle soreness, fatigue, and RPE from standardised warm-up at 24 h postexercise. The current findings suggest that compression may assist in perceptual recovery from manual-labour exercise with implications for the ability to perform subsequent work bouts.
Tian, Ye; Zhao, Jiexiu; Zhao, Binxiu; Gao, Qi; Xu, Jincheng; Liu, Dongsen
Currently, it is unclear which index of haematological parameters could be used to most easily monitor iron deficiency during endurance training. To address this question, 16 male Wistar rats were randomly assigned to two groups: a sedentary group (n = 8) and an exercised group (n = 8). Initially, animals in the exercise group started running on a treadmill at a rate of 30 m/min, on a 0% grade, for 1 min/session. Running time was gradually increased by 2 min/day. The training plan was one session per day during the initial 2 weeks and two sessions per day during the third to ninth week. At the end of the 9-week experiment, we analysed the blood of the experimental animals for haemoglobin levels, erythrocyte numbers, haematocrit, serum iron levels, total iron binding capacity, transferrin saturation, serum ferritin levels and soluble transferrin receptor (sTfR) levels, and we calculated the ratio of sTfR/ferritin. Erythrocyte numbers, haemoglobin levels and haematocrit values were decreased after 9 weeks of exercise, but sTfR and sTfR/ferritin values were increased (P < 0.01 or P < 0.05). The training regime significantly increased TfR mRNA levels in the bone marrow cells of the exercised rats compared with the sedentary group (1.8 ± 0.5 vs. 1.1 ± 0.2, P < 0.01). These results revealed a significant correlation between TfR levels in the bone marrow cells and the ratio of sTfR/ferritin (r = 0.517; P < 0.01) and sTfR levels (r = 0.206; P < 0.05) in sedentary and exercised rats. In conclusion, we show that sTfR indices and the ratio of sTfR/ferritin could be useful indicators for monitoring iron deficiency during endurance training.
Francescato, Maria Pia; Stel, Giuliana; Stenner, Elisabetta; Geat, Mario
Physical activity in patients with type 1 diabetes (T1DM) is hindered because of the high risk of glycemic imbalances. A recently proposed algorithm (named Ecres) estimates well enough the supplemental carbohydrates for exercises lasting one hour, but its performance for prolonged exercise requires validation. Nine T1DM patients (5M/4F; 35-65 years; HbA1c 54 ± 13 mmol · mol(-1)) performed, under free-life conditions, a 3-h walk at 30% heart rate reserve while insulin concentrations, whole-body carbohydrate oxidation rates (determined by indirect calorimetry) and supplemental carbohydrates (93% sucrose), together with glycemia, were measured every 30 min. Data were subsequently compared with the corresponding values estimated by the algorithm. No significant difference was found between the estimated insulin concentrations and the laboratory-measured values (p = NS). Carbohydrates oxidation rate decreased significantly with time (from 0.84 ± 0.31 to 0.53 ± 0.24 g · min(-1), respectively; p < 0.001), being estimated well enough by the algorithm (p = NS). Estimated carbohydrates requirements were practically equal to the corresponding measured values (p = NS), the difference between the two quantities amounting to -1.0 ± 6.1 g, independent of the elapsed exercise time (time effect, p = NS). Results confirm that Ecres provides a satisfactory estimate of the carbohydrates required to avoid glycemic imbalances during moderate intensity aerobic physical activity, opening the prospect of an intriguing method that could liberate patients from the fear of exercise-induced hypoglycemia.
van Loon, Luc J C
Dietary protein ingestion following exercise increases muscle protein synthesis rates, stimulates net muscle protein accretion, and facilitates the skeletal muscle adaptive response to prolonged exercise training. Furthermore, recent studies show that protein ingestion before and during exercise also increases muscle protein synthesis rates during resistance- and endurance-type exercise. Therefore, protein ingestion before and during prolonged exercise may represent an effective dietary strategy to enhance the skeletal muscle adaptive response to each exercise session by extending the window of opportunity during which the muscle protein synthetic response is facilitated. Protein ingestion during exercise has also been suggested to improve performance capacity acutely. However, recent studies investigating the impact of protein ingestion during exercise on time trial performance, as opposed to time to exhaustion, do not report ergogenic benefits of protein ingestion. Therefore, it is concluded that protein ingestion with carbohydrate during exercise does not further improve exercise performance when compared with the ingestion of ample amounts of carbohydrate only.
Jensen, Line; Gejl, Kasper D; Ørtenblad, Niels; Nielsen, Jakob L; Bech, Rune D; Nygaard, Tobias; Sahlin, Kent; Frandsen, Ulrik
The aim was to determine if the metabolic adaptations, particularly PGC-1α and downstream metabolic genes were affected by restricting CHO following an endurance exercise bout in trained endurance athletes. A second aim was to compare baseline expression level of these genes to untrained. Elite endurance athletes (VO2max 66 ± 2 mL·kg−1·min−1, n = 15) completed 4 h cycling at ∼56% VO2max. During the first 4 h recovery subjects were provided with either CHO or only H2O and thereafter both groups received CHO. Muscle biopsies were collected before, after, and 4 and 24 h after exercise. Also, resting biopsies were collected from untrained subjects (n = 8). Exercise decreased glycogen by 67.7 ± 4.0% (from 699 ± 26.1 to 239 ± 29.5 mmol·kg−1·dw−1) with no difference between groups. Whereas 4 h of recovery with CHO partly replenished glycogen, the H2O group remained at post exercise level; nevertheless, the gene expression was not different between groups. Glycogen and most gene expression levels returned to baseline by 24 h in both CHO and H2O. Baseline mRNA expression of NRF-1, COX-IV, GLUT4 and PPAR-α gene targets were higher in trained compared to untrained. Additionally, the proportion of type I muscle fibers positively correlated with baseline mRNA for PGC-1α, TFAM, NRF-1, COX-IV, PPAR-α, and GLUT4 for both trained and untrained. CHO restriction during recovery from glycogen depleting exercise does not improve the mRNA response of markers of mitochondrial biogenesis. Further, baseline gene expression of key metabolic pathways is higher in trained than untrained. PMID:25677542
Schmitz, Randy J.; Cone, John C.; Tritsch, Amanda J.; Pye, Michele L.; Montgomery, Melissa M.; Henson, Robert A.; Shultz, Sandra J.
Background: As injury rates rise in the later stages of sporting activities, a better understanding of lower extremity biomechanics in the later phases of gamelike situations may improve training and injury prevention programs. Hypothesis: Lower extremity biomechanics of a drop-jump task (extracted from a principal components analysis) would reveal factors associated with risk of anterior cruciate ligament injury during a 90-minute individualized intermittent exercise protocol (IEP) and for 1 hour following the IEP. Study Design: Controlled laboratory study. Level of Evidence: Level 4. Methods: Fifty-nine athletes (29 women, 30 men) completed 3 sessions. The first session assessed fitness for an IEP designed to simulate the demands of a soccer match. An experimental session assessed drop-jump biomechanics, after a dynamic warm-up, every 15 minutes during the 90-minute IEP, and for 1 hour following the IEP. A control session with no exercise assessed drop-jump performance at the same intervals. Results: Two biomechanical factors early in the first half (hip flexion at initial contact and hip loading; ankle loading and knee shear force) decreased at the end of the IEP and into the 60-minute recovery period, while a third factor (knee loading) decreased only during the recovery period (P ≤ 0.05). Conclusion: The individualized sport-specific IEP may have more subtle effects on landing biomechanics when compared with short-term, exhaustive fatigue protocols. Clinical Relevance: Potentially injurious landing biomechanics may not occur until the later stages of soccer activity. PMID:24587862
Price, Mike James; Cripps, David
This study examined the effects of combined glucose and sodium bicarbonate ingestion prior to intermittent exercise. Ninemales (mean ± s age 25.4 ± 6.6 years, body mass 78.8 ± 12.0 kg, maximal oxygen uptake (VO2 max)) 47.0 ± 7 ml · kg · min(-1)) undertook 4 × 45 min intermittent cycling trials including 15 × 10 s sprints one hour after ingesting placebo (PLA), glucose (CHO), sodium bicarbonate (NaHCO3) or a combined CHO and NaHCO3 solution (COMB). Post ingestion blood pH (7.45 ± 0.03, 7.46 ± 0.03, 7.32 ± 0.05, 7.32 ± 0.01) and bicarbonate (30.3 ± 2.1, 30.7 ± 1.8, 24.2 ± 1.2, 24.0 ± 1.8 mmol · l(-1)) were greater for NaHCO3 and COMB when compared to PLA and CHO, remaining elevated throughout exercise (main effect for trial; P < 0.05). Blood lactate concentration was greatest throughout exercise for NaHCO3 and COMB (main effect for trial; P < 0.05). Blood glucose concentration was greatest 15 min post-ingestion for CHO followed by COMB, NaHCO3 and PLA (7.13 ± 0.60, 5.58 ± 0.75, 4.51 ± 0.56, 4.46 ± 0.59 mmol · l(-1), respectively; P < 0.05). Gastrointestinal distress was lower during COMB compared to NaHCO3 at 15 min post-ingestion (P < 0.05). No differences were observed for sprint performance between trials (P = 1.00). The results of this study suggest that a combined CHO and NaHCO3 beverage reduced gastrointestinal distress and CHO availability but did not improve performance. Although there was no effect on performance an investigation of the effects in more highly trained individuals may be warranted.
Röcker, Lothar; Hinz, Katrin; Holland, Karsten; Gunga, Hanns-Christian; Vogelgesang, Jens; Kiesewetter, Holger
Numerous reports have described a poor iron status in female endurance athletes. However, the traditionally applied indicators of iron status (hemoglobin, ferritin, transferrin) may not truly reflect the iron status. Therefore we studied the newly developed soluble transferrin receptor and other indicators of iron status in twelve female endurance athletes before and after a triathlon race. Resting values showed a poor iron status in the participants of the race. Serum TfR concentration increased slightly after the race. However, if the values are corrected for hemoconcentration no change could be found. Hemoglobin, serum ferritin and transferrin values were increased after the race.
Prolonged exposure to microgravity results in chronic physiological adaptations including skeletal muscle atrophy, cardiovascular deconditioning, and bone demineralization. To attenuate the negative consequences of weightlessness during spaceflight missions, crewmembers perform moderate- to high-load resistance exercise in conjunction with aerobic (cycle and treadmill) exercise. Recent evidence from ground-based studies suggests that low-load blood flow-restricted (BFR) resistance exercise training can increase skeletal muscle size, strength, and endurance when performed in a variety of ambulatory populations. This training methodology couples a remarkably low exercise training load (approximately 20%–50% one repetition maximum (1RM)) with an inflated external cuff (width, ranging between approximately 30–90 mm; pressure, ranging between approximately 100–250 mmHg) that is placed around the exercising limb. BFR aerobic (walking and cycling) exercise training methods have also recently emerged in an attempt to enhance cardiovascular endurance and functional task performance while incorporating minimal exercise intensity. Although both forms of BFR exercise training have direct implications for individuals with sarcopenia and dynapenia, the application of BFR exercise training during exposure to microgravity to prevent deconditioning remains controversial. The aim of this review is to present an overview of BFR exercise training and discuss the potential usefulness of this method as an adjunct exercise countermeasure during prolonged spaceflight. The work will specifically emphasize ambulatory BFR exercise training adaptations, mechanisms, and safety and will provide directions for future research. PMID:23849078
Andonian, Pierre; Viallon, Magalie; Le Goff, Caroline; de Bourguignon, Charles; Tourel, Charline; Morel, Jérome; Giardini, Guido; Gergelé, Laurent; Millet, Grégoire P; Croisille, Pierre
In sports medicine, there is increasing interest in quantifying the elastic properties of skeletal muscle, especially during extreme muscular stimulation, to improve our understanding of the impact of alterations in skeletal muscle stiffness on resulting pain or injuries, as well as the mechanisms underlying the relationships between these parameters. Our main objective was to determine whether real-time shear-wave elastography (SWE) can monitor changes in quadriceps muscle elasticity during an extreme mountain ultra-marathon, a powerful mechanical stress model. Our study involved 50 volunteers participating in an extreme mountain marathon (distance: 330 km, elevation: +24,000 m). Quantitative SWE velocity and shear modulus measurements were performed in most superficial quadriceps muscle heads at the following 4 time points: before the race, halfway through the race, upon finishing the race and after recovery (+48 h). Blood biomarker levels were also measured. A significant decrease in the quadriceps shear modulus was observed upon finishing the race (3.31±0.61 kPa) (p<0.001) compared to baseline (3.56±0.63 kPa), followed by a partial recovery +48 h after the race (3.45±0.6 kPa) (p = 0.002) across all muscle heads, as well as for each of the following three muscle heads: the rectus femoris (p = 0.003), the vastus medialis (p = 0.033) and the vastus lateralis (p = 0.001). Our study is the first to assess changes in muscle stiffness during prolonged extreme physical endurance exercises based on shear modulus measurements using non-invasive SWE. We concluded that decreases in stiffness, which may have resulted from quadriceps overuse in the setting of supra-physiological stress caused by the extreme distance and unique elevation of the race, may have been responsible for the development of inflammation and muscle swelling. SWE may hence represent a promising tool for monitoring physiologic or pathological variations in muscle stiffness and may be useful for
Andonian, Pierre; Viallon, Magalie; Le Goff, Caroline; de Bourguignon, Charles; Tourel, Charline; Morel, Jérome; Giardini, Guido; Gergelé, Laurent; Millet, Grégoire P.; Croisille, Pierre
In sports medicine, there is increasing interest in quantifying the elastic properties of skeletal muscle, especially during extreme muscular stimulation, to improve our understanding of the impact of alterations in skeletal muscle stiffness on resulting pain or injuries, as well as the mechanisms underlying the relationships between these parameters. Our main objective was to determine whether real-time shear-wave elastography (SWE) can monitor changes in quadriceps muscle elasticity during an extreme mountain ultra-marathon, a powerful mechanical stress model. Our study involved 50 volunteers participating in an extreme mountain marathon (distance: 330 km, elevation: +24,000 m). Quantitative SWE velocity and shear modulus measurements were performed in most superficial quadriceps muscle heads at the following 4 time points: before the race, halfway through the race, upon finishing the race and after recovery (+48 h). Blood biomarker levels were also measured. A significant decrease in the quadriceps shear modulus was observed upon finishing the race (3.31±0.61 kPa) (p<0.001) compared to baseline (3.56±0.63 kPa), followed by a partial recovery +48 h after the race (3.45±0.6 kPa) (p = 0.002) across all muscle heads, as well as for each of the following three muscle heads: the rectus femoris (p = 0.003), the vastus medialis (p = 0.033) and the vastus lateralis (p = 0.001). Our study is the first to assess changes in muscle stiffness during prolonged extreme physical endurance exercises based on shear modulus measurements using non-invasive SWE. We concluded that decreases in stiffness, which may have resulted from quadriceps overuse in the setting of supra-physiological stress caused by the extreme distance and unique elevation of the race, may have been responsible for the development of inflammation and muscle swelling. SWE may hence represent a promising tool for monitoring physiologic or pathological variations in muscle stiffness and may be useful for
Regular and prolonged exercise is associated with increased left ventricular wall thickness that can overlap with hypertrophic cardiomyopathy (HCM). Differentiating physiological from pathological hypertrophy has important implications, since HCM is the commonest cause of exercise-related sudden cardiac death in young individuals. Most deaths have been reported in intermittent 'start-stop' sports such as football (soccer) and basketball. The theory is that individuals with HCM are unable to augment stroke volume sufficiently to meet the demands of endurance sports and are accordingly 'selected-out' of participation in such events. We report the case of an ultra-endurance athlete with 25 years of > 50 km competitive running experience, with genetically confirmed HCM; thereby demonstrating that these can be two compatible entities. PMID:22122802
Wu, Wei-Jie; Wang, Shan-Huan; Ling, Wei; Geng, Li-Jun; Zhang, Xiao-Xi; Yu, Lan; Chen, Jun; Luo, Jiang-Xi; Zhao, Hai-Lu
Abstract Disturbance of oxygen–carbon dioxide homeostasis has an impact on cancer. Little is known about the effect of breath training on cancer patients. Here we report our 10-year experience with morning breathing exercises (MBE) in peer-support programs for cancer survivors. We performed a cohort study to investigate long-term surviving patients with lung cancer (LC) and nasopharyngeal cancer (NPC) who practiced MBE on a daily basis. End-tidal breath holding time (ETBHT) after MBE was measured to reflect improvement in alveolar O2 pressure and alveolar CO2 pressure capacity. Patients (female, 57) with a diagnosis of LC (90 patients) and NPC (32 patients) were included. Seventy-six of them were MBE trainees. Average survival years were higher in MBE trainees (9.8 ± 9.5) than nontrainees (3.3 ± 2.8). The 5-year survival rate was 56.6% for MBE trainees and 19.6% for nontrainees (RR = 5.371, 95% CI = 2.271–12.636, P < 0.001). Survival probability of the trainees further increased 17.9-fold for the 10-year survival rate. Compared with the nontrainees, the MBE trainees shows no significant differences in ETBHT (baseline, P = 0.795; 1–2 years, P = 0.301; 3–4 years, P = 0.059) at baseline and within the first 4 years. From the 5th year onwards, significant improvements were observed in ETBHT, aCO2%, PaCO2, and PaO2 (P = 0.028). In total, 18 trainees (40.9%) and 20 nontrainees (74.1%) developed new metastasis (RR = 0.315, 95% CI = 0.108–0.919, P = 0.031). MBE might benefit for the long-term survival in patients with LC and NPC due to improvement in hyperventilation. PMID:28079815
Marinho, R; Ropelle, E R; Cintra, D E; De Souza, C T; Da Silva, A S R; Bertoli, F C; Colantonio, E; D'Almeida, V; Pauli, J R
Hepatic insulin resistance is the major contributor to fasting hyperglycemia in type 2 diabetes. The protein kinase Akt plays a central role in the suppression of gluconeogenesis involving forkhead box O1 (Foxo1) and peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α), and in the control of glycogen synthesis involving the glycogen synthase kinase beta (GSK3β) in the liver. It has been demonstrated that endosomal adaptor protein APPL1 interacts with Akt and blocks the association of Akt with its endogenous inhibitor, tribbles-related protein 3 (TRB3), improving the action of insulin in the liver. Here, we demonstrated that chronic exercise increased the basal levels and insulin-induced Akt serine phosphorylation in the liver of diet-induced obese mice. Endurance training was able to increase APPL1 expression and the interaction between APPL1 and Akt. Conversely, training reduced both TRB3 expression and TRB3 and Akt association. The positive effects of exercise on insulin action are reinforced by our findings that showed that trained mice presented an increase in Foxo1 phosphorylation and Foxo1/PGC-1α association, which was accompanied by a reduction in gluconeogenic gene expressions (PEPCK and G6Pase). Finally, exercised animals demonstrated increased at basal and insulin-induced GSK3β phosphorylation levels and glycogen content at 24 h after the last session of exercise. Our findings demonstrate that exercise increases insulin action, at least in part, through the enhancement of APPL1 and the reduction of TRB3 expression in the liver of obese mice, independently of weight loss.
WANG-PRICE, SHARON; ALMADAN, MOHAMMAD; STODDARD, CARISSA; MOORE, DUSTIN
Literature has not shown the minimum time required to recover from muscle fatigue after a prolonged trunk isometric contraction. The purpose of this study was to determine if the lumbar multifidus (LM) and gluteus maximus (GM) muscles would recover from fatigue after three different rest periods following performance of a back extension endurance test. Endurance time and electromyographic (EMG) activity of bilateral LM and GM muscles were collected from 12 healthy adults during a modified Biering-Sørensen test. On three separate visits, each participant performed two modified Biering-Sørensen tests, one before and one after a rest period (3, 6 or 9 min). For each endurance test, endurance time was measured and both mean and median EMG frequency fatigue rates were calculated. The results showed a significantly reduced endurance time and normalized mean frequency fatigue rates on the second modified Biering-Sørensen endurance test regardless of the rest periods (3, 6, and 9 min). This suggests that adequate rest should be considered for fatigue recovery when designing a back and hip endurance exercise program, and that future studies should investigate a rest time longer than 9 minutes for fatigue recovery following a modified Biering-Sørensen endurance test. PMID:28344736
Wagner, Sandra; Knechtle, Beat; Knechtle, Patrizia; Rüst, Christoph Alexander; Rosemann, Thomas
We investigated the prevalence of exercise-associated hyponatremia (EAH) in 25 male and 11 female open-water ultra-endurance swimmers participating in the 'Marathon-Swim' in Lake Zurich, Switzerland, covering a distance of 26.4 km. Changes in body mass, fat mass, skeletal muscle mass, total body water, urine specific gravity, plasma sodium concentration [Na(+)] and haematocrit were determined. Two males (8%) and four females (36%) developed EAH where one female was symptomatic with plasma sodium [Na(+)] of 127 mmol/L. Body mass and plasma [Na(+)] decreased (p < 0.05). The changes in body mass correlated in both male and female swimmers to post-race plasma [Na(+)] (r = -0.67, p = 0.0002 and r = -0.80, p = 0.0034, respectively) and changes in plasma [Na(+)] (r = -0.68, p = 0.0002 and r = -0.79, p = 0.0039, respectively). Fluid intake was neither associated with changes in body mass, post-race plasma [Na(+)] or the change in plasma [Na(+)]. Sodium intake showed no association with either the changes in plasma [Na(+)] or post-race plasma [Na(+)]. We concluded that the prevalence of EAH was greater in female than in male open-water ultra-endurance swimmers.
Randers, Morten Bredsgaard; Andersen, Jesper L; Petersen, Jesper; Sundstrup, Emil; Jakobsen, Markus D; Bangsbo, Jens; Saltin, Bengt; Krustrup, Peter
The aim was to investigate performance variables and indicators of cardiovascular health profile in elderly soccer players (SP, n = 11) compared to endurance-trained (ET, n = 8), strength-trained (ST, n = 7) and untrained (UT, n = 7) age-matched men. The 33 men aged 65-85 years underwent a testing protocol including measurements of cycle performance, maximal oxygen uptake (VO2max) and body composition, and muscle fibre types and capillarisation were determined from m. vastus lateralis biopsy. In SP, time to exhaustion was longer (16.3 ± 2.0 min; P < 0.01) than in UT (+48%) and ST (+41%), but similar to ET (+1%). Fat percentage was lower (P < 0.05) in SP (-6.5% points) than UT but not ET and ST. Heart rate reserve was higher (P < 0.05) in SP (104 ± 16 bpm) than UT (+21 bpm) and ST (+24 bpm), but similar to ET (+2 bpm), whereas VO2max was not significantly different in SP (30.2 ± 4.9 ml O2 · min(-1) · kg(-1)) compared to UT (+14%) and ST (+9%), but lower (P < 0.05) than ET (-22%). The number of capillaries per fibre was higher (P < 0.05) in SP than UT (53%) and ST (42%) but similar to ET. SP had less type IIx fibres than UT (-12% points). In conclusion, the exercise performance and cardiovascular health profile are markedly better for lifelong trained SP than for age-matched UT controls. Incremental exercise capacity and muscle aerobic capacity of SP are also superior to lifelong ST athletes and comparable to endurance athletes.
by the rhomboids, serratus anterior , trapezius, and pectoralis minor. The subclavis depresses the clavicle. The same arm muscles extend again and the...could not do five knee pushups comprised Group 2. Her study revealed that the pushup exercise involved in order of importance: the anterior deltoid... anterior shoulder muscles, and the chest muscles. These are the same muscles used in the criterion tests--the pushup and the bench press exercises
Paulin, Fernanda Viana; Zagatto, Alessandro Moura; Chiappa, Gaspar R; Müller, Paulo de Tarso
Vitamin B12 is essential in the homocysteine, mitochondrial, muscle and hematopoietic metabolisms, and its effects on exercise tolerance and kinetics adjustments of oxygen consumption (V'O2p) in rest-to-exercise transition in COPD patients are unknown. This randomized, double-blind, controlled study aimed to verify a possible interaction between vitamin B12 supplementation and these outcomes. After recruiting 69 patients, 35 subjects with moderate-to-severe COPD were eligible and 32 patients concluded the study, divided into four groups (n = 8 for each group): 1. rehabilitation group; 2. rehabilitation plus B12 group; 3. B12 group; and 4. placebo group. The primary endpoint was cycle ergometry endurance before and after 8 weeks and the secondary endpoints were oxygen uptake kinetics parameters (time constant). The prevalence of vitamin B12 deficiency was high (34.4%) and there was a statistically significant interaction (p < 0.05), favoring a global effect of supplementation on exercise tolerance in the supplemented groups compared to the non-supplemented groups, even after adjusting for confounding variables (p < 0.05). The same was not found for the kinetics adjustment variables (τV'O2p and MRTV'O2p, p > 0.05 for both). Supplementation with vitamin B12 appears to lead to discrete positive effects on exercise tolerance in groups of subjects with more advanced COPD and further studies are needed to establish indications for long-term supplementation.
Koehler, Karsten; Braun, Hans; de Marees, Markus; Geyer, Hans; Thevis, Mario; Mester, Joachim; Schaenzer, Wilhelm
Glycerol is prohibited as a masking agent by the World Anti-Doping Agency and a urinary threshold has recently been recommended. However, little is known about urinary glycerol excretion after exercise, when (1) exogenous glycerol is metabolized increasingly and (2) endogenous glycerol levels are elevated. The purpose of the placebo-controlled cross-over study was to determine the effects of pre-exercise glycerol administration on glycerol metabolism, urinary excretion, and selected blood parameters. After administration of glycerol (G; 1.0 g/kg body weight (BW) + 25 ml fluid/kg BW) or placebo (P; 25 ml fluid/kg), 14 cyclists exercised 90 min at 60% VO2max . Samples were taken at 0 h (before administration), 2.5 h (before exercise), 4 h (after exercise) and 6.5 h and additional urine samples were collected until 24 h. Exercise increased endogenous plasma glycerol (0.51 ± 0.21 mmol/l) but peak concentrations were much higher in G (2.5 h: 15.6 ± 7.8 mmol/l). Urinary glycerol increased rapidly (58,428 ± 71,084 µg/ml after 2.5 h) and was significantly higher than in P until 13.6 ± 0.9 h (p < 0.01). In comparison with placebo administration, G caused significantly greater changes in plasma volume and haemoglobin concentrations after 2.5 h. BW and urine production were significantly different between P and G after 2.5 h and post-exercise. Despite exercise-induced increases in endogenous glycerol in the control group, urinary excretion remained well below the previously recommended threshold. In addition, exercise-related glycerol degradation did not appear to negatively affect the detection of exogenously administered glycerol.
Radikova, Zofia; Ksinantova, Lucia; Kaciuba-Uscilko, Hanna; Nazar, Krystyna; Vigas, Milan; Koska, Juraj
Physical inactivity during space flight has a profound effect on glucose metabolism. The aim of this study was to test whether endurance training (ET) may improve a negative effect of subsequent -6∘ head-down bed rest (HDBR) on glucose metabolism. Fourteen healthy males completed the study consisting of 6 weeks lasting ET followed by 6 days HDBR. Treadmill exercise at 80% of pre-training VO2max and 75 g oral glucose tolerance test (OGTT) were performed before and after ET as well as after HDBR. ET increased VO2max by 11%. ET significantly lowered while HDBR had no effect on fasting and OGTT plasma glucose levels. ET had no effect while HDBR was followed by an augmentation of insulin and C-peptide response to OGTT. Insulin sensitivity tended to increase after ET and to decrease during HDBR, however, mostly without statistical significance. Plasma glucose, insulin and C-peptide response to exercise were elevated after HDBR only. Our study shows that antecedent physical training could ameliorate a negative effect of simulated microgravity on insulin-mediated glucose metabolism.
Endogenous glucose production (EGP) occurs via hepatic glycogenolysis (GLY) and gluconeogenesis (GNG) and plays an important role in maintaining euglycemia. Rates of GLY and GNG increase during exercise in athletes following a mixed macronutrient diet; however these processes have not been investiga...
Rose, R J; Purdue, R A; Hensley, W
The effects of prolonged strenous exercise on the plasma concentrations of sodium, potassium, calcium, chloride, bicarbonate, phosphate, albumin, cholesterol, glucose, creatinine, bilirubin, alkaline phosphatase, creatine phosphokinase, lactic dehydrogenase and asparate amino transferase were studied in a group of 26 horses competing in an endurance ride. There were significant changes in most parameters, when control values were compared with those taken immediately after the ride. There was also a significant correlation between several biochemical parameters and heart rate taken 30 minutes after the ride. When faster and slower horses were compared, significant differences were found only in phosphate and glucose values.
Thomas, Kevin; Morris, Penelope; Stevenson, Emma
This study examined the effects of 3 recovery drinks on endurance performance following glycogen-depleting exercise. Nine trained male cyclists performed 3 experimental trials, in a randomized counter-balanced order, consisting of a glycogen-depleting trial, a 4-h recovery period, and a cycle to exhaustion at 70% power at maximal oxygen uptake. At 0 and 2 h into the recovery period, participants consumed chocolate milk (CM), a carbohydrate replacement drink (CR), or a fluid replacement drink (FR). Participants cycled 51% and 43% longer after ingesting CM (32 +/- 11 min) than after ingesting CR (21 +/- 8 min) or FR (23 +/- 8 min). CM is an effective recovery aid after prolonged endurance exercise for subsequent exercise at low-moderate intensities.
Martin, Brian J.; MacInnis, Martin J.; Skelly, Lauren E.; Tarnopolsky, Mark A.; Gibala, Martin J.
Aims We investigated whether sprint interval training (SIT) was a time-efficient exercise strategy to improve insulin sensitivity and other indices of cardiometabolic health to the same extent as traditional moderate-intensity continuous training (MICT). SIT involved 1 minute of intense exercise within a 10-minute time commitment, whereas MICT involved 50 minutes of continuous exercise per session. Methods Sedentary men (27±8y; BMI = 26±6kg/m2) performed three weekly sessions of SIT (n = 9) or MICT (n = 10) for 12 weeks or served as non-training controls (n = 6). SIT involved 3x20-second ‘all-out’ cycle sprints (~500W) interspersed with 2 minutes of cycling at 50W, whereas MICT involved 45 minutes of continuous cycling at ~70% maximal heart rate (~110W). Both protocols involved a 2-minute warm-up and 3-minute cool-down at 50W. Results Peak oxygen uptake increased after training by 19% in both groups (SIT: 32±7 to 38±8; MICT: 34±6 to 40±8ml/kg/min; p<0.001 for both). Insulin sensitivity index (CSI), determined by intravenous glucose tolerance tests performed before and 72 hours after training, increased similarly after SIT (4.9±2.5 to 7.5±4.7, p = 0.002) and MICT (5.0±3.3 to 6.7±5.0 x 10−4 min-1 [μU/mL]-1, p = 0.013) (p<0.05). Skeletal muscle mitochondrial content also increased similarly after SIT and MICT, as primarily reflected by the maximal activity of citrate synthase (CS; P<0.001). The corresponding changes in the control group were small for VO2peak (p = 0.99), CSI (p = 0.63) and CS (p = 0.97). Conclusions Twelve weeks of brief intense interval exercise improved indices of cardiometabolic health to the same extent as traditional endurance training in sedentary men, despite a five-fold lower exercise volume and time commitment. PMID:27115137
Abreu, Phablo; Mendes, Sávio Victor Diógenes; Ceccatto, Vânia Marilande; Hirabara, Sandro Massao
Although the requirement of satellite cells activation and expansion following injury, mechanical load or growth stimulus provoked by resistance exercise has been well established, their function in response to aerobic exercise adaptation remains unclear. A clear relationship between satellite cell expansion in fiber-type specific myosin heavy chain and aerobic performance has been related, independent of myonuclear accretion or muscle growth. However, the trigger for this activation process is not fully understood yet and it seems to be a multi-faceted and well-orchestrated process. Emerging in vitro studies suggest a role for metabolic pathways and oxygen availability for satellite cell activation, modulating the self-renewal potential and cell fate control. The goal of this review is to describe and discuss the current knowledge about the satellite cell activation and expansion in response to aerobic exercise adaptation in human and rodent models. Additionally, findings about the in vitro metabolic control, which seems be involved in the satellite cell activation and cell fate control, are presented and discussed.
Impact of Endurance Exercise Training in the Fasted State on Muscle Biochemistry and Metabolism in Healthy Subjects: Can These Effects be of Particular Clinical Benefit to Type 2 Diabetes Mellitus and Insulin-Resistant Patients?
Hansen, Dominique; De Strijcker, Dorien; Calders, Patrick
Exercise training intervention is a cornerstone in the care of type 2 diabetes mellitus (T2DM) and insulin resistance (IR), and it is pursued in order to optimize exercise interventions for these patients. In this regard, the nutritional state of patients during exercise (being in the fed or fasted state) can be of particular interest. The aim of the present review is to describe the impact of endurance exercise (training) in the fasted versus fed state on parameters of muscle biochemistry and metabolism linked to glycemic control or insulin sensitivity in healthy subjects. From these data it can then be deduced whether exercise training in the fasted state may be relevant to patients with T2DM or IR. In healthy subjects, acute endurance exercise in the fasted state is accompanied by lower blood insulin and elevated blood free fatty acid concentrations, stable blood glucose concentrations (in the first 60-90 min), superior intramyocellular triacylglycerol oxidation and whole-body lipolysis, and muscle glycogen preservation. Long-term exercise training in the fasted state in healthy subjects is associated with greater improvements in insulin sensitivity, basal muscle fat uptake capacity, and oxidation. Therefore, promising results of exercise (training) in the fasted state have been found in healthy subjects on parameters of muscle biochemistry and metabolism linked to insulin sensitivity and glycemic control. Whether exercise training intervention in which exercise sessions are organized in the fasted state may be more effective in improving insulin sensitivity or glycemic control in T2DM patients and insulin-resistant individuals warrants investigation.
Banzet, Sébastien; Koulmann, Nathalie; Simler, Nadine; Sanchez, Hervé; Chapot, Rachel; Serrurier, Bernard; Peinnequin, André; Bigard, Xavier
Prolonged intense exercise is challenging for the liver to maintain plasma glucose levels. Hormonal changes cannot fully account for exercise-induced hepatic glucose production (HGP). Contracting skeletal muscles release interleukin-6 (IL-6), a cytokine able to increase endogenous glucose production during exercise. However, whether this is attributable to a direct effect of IL-6 on liver remains unknown. Here, we studied hepatic glycogen, gluconeogenic genes, and IL-6 signaling in response to one bout of exhaustive running exercise in rats. To determine whether IL-6 can modulate gluconeogenic gene mRNA independently of exercise, we injected resting rats with recombinant IL-6. Exhaustive exercise resulted in a profound decrease in liver glycogen and an increase in gluconeogenic gene mRNA levels, phosphoenolpyruvate-carboxykinase (PEPCK), glucose-6-phosphatase (G6P), and peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), suggesting a key role for gluconeogenesis in hepatic glucose production. This was associated to an active IL-6 signaling in liver tissue, as shown by signal transducer and activator of transcription and CAAT/enhancer binding protein-beta phosphorylation and IL-6-responsive gene mRNA levels at the end of exercise. Recombinant IL-6 injection resulted in an increase in IL-6-responsive gene mRNA levels in the liver. We found a dose-dependent increase in PEPCK gene mRNA strongly correlated with IL-6-induced gene mRNA levels. No changes in G6P and PGC-1alpha mRNA levels were found. Taken together, our results suggest that, during very demanding exercise, muscle-derived IL-6 could help increase HGP by directly upregulating PEPCK mRNA abundance.
Yeh, Tzu-Shao; Chan, Kuei-Hui; Hsu, Mei-Chich; Liu, Jen-Fang
The purpose of this study was to investigate the effects of a proprietary blend of soybean peptides, taurine, Pueraria isoflavone, and ginseng saponin complex (STPG capsule) on exercise performance in humans. Fourteen male volunteers were randomly assigned to two crossover treatments in which they consumed either four STPG capsules (STPG treatment) or placebo (P treatment) for 15 days before a 75% maximal oxygen uptake (VO(2max)) exhaustive cycling test. Blood samples and respiratory gas were collected prior to the exercise (Pre-Ex), at 10 (Ex-10), 15 (Ex-15), 20 (Ex-20), and 25 (Ex-25) minutes during exercise, and immediately after exercise (exhaustion) to assess the blood metabolites, cardiorespiratory responses, and energy substrate utilization. The result showed that exercise time to exhaustion of the 75% (VO(2max)) exhaustive cycling test of the STPG-treated subjects was significantly greater than with the P treatment (30.99 ± 2.01 vs. 28.05 ± 1.48 minutes). The plasma lactate concentrations at Ex-20 and Ex-25 in the STPG treatment were significantly lower with STPG treatment than with P treatment (10.5 ± 0.7 vs. 11.5 ± 0.8 and 10.7 ± 0.9 vs.12.3 ± 1.0 mmol/L, respectively). Nonesterified fatty acid levels at Ex-15, Ex-20, Ex-25, and exhaustion in the STPG group (0.27 ± 0.03, 0.32 ± 0.04, 0.32 ± 0.06, and 0.37 ± 0.05 mmol/L, respectively) were significantly higher than those in the P treatment (0.21 ± 0.03, 0.23 ± 0.03, 0.24 ± 0.03, and 0.25 ± 0.03 mmol/L, respectively). It was concluded that supplementation of four capsules (2 g) of STPG complex, consisting of soybean peptides, taurine, Pueraria isoflavone, and ginseng saponin, for 15 days was effective in promoting utilization of free fatty acids and improving exhaustive cycling test performance in humans.
Broadbent, James; Sampson, Dayle; Sabapathy, Surendran; Haseler, Luke J; Wagner, Karl-Heinz; Bulmer, Andrew C; Peake, Jonathan M; Neubauer, Oliver
It remains incompletely understood whether there is an association between the transcriptome profiles of skeletal muscle and blood leukocytes in response to exercise or other physiological stressors. We have previously analyzed the changes in the muscle and blood neutrophil transcriptome in eight trained men before and 3, 48, and 96 h after 2 h cycling and running. Because we collected muscle and blood in the same individuals and under the same conditions, we were able to directly compare gene expression between the muscle and blood neutrophils. Applying weighted gene coexpression network analysis (WGCNA) as an advanced network-driven method to these original data sets enabled us to compare the muscle and neutrophil transcriptomes in a rigorous and systematic manner. Two gene networks were identified that were preserved between skeletal muscle and blood neutrophils, functionally related to mitochondria and posttranslational processes. Strong preservation measures (Zsummary > 10) for both muscle-neutrophil gene networks were evident within the postexercise recovery period. Muscle and neutrophil gene coexpression was strongly correlated in the mitochondria-related network (r = 0.97; P = 3.17E-2). We also identified multiple correlations between muscular gene subnetworks and exercise-induced changes in blood leukocyte counts, inflammation, and muscle damage markers. These data reveal previously unidentified gene coexpression between skeletal muscle and blood neutrophils following exercise, showing the value of WGCNA to understand exercise physiology. Furthermore, these findings provide preliminary evidence in support of the notion that blood neutrophil gene networks may potentially help us to track physiological and pathophysiological changes in the muscle.NEW & NOTEWORTHY By using weighted gene coexpression network analysis, an advanced bioinformatics method, we have identified previously unknown, functional gene networks that are preserved between skeletal muscle
de Paoli, Frank Vincenzo; Broch-Lips, Martin; Pedersen, Thomas Holm; Nielsen, Ole Bækgaard
Resting skeletal muscle fibres have a large membrane Cl− conductance (GCl) that dampens their excitability. Recently, however, muscle activity was shown to induce PKC-mediated reduction in GCl in rat muscles of 40–90%. To examine the physiological significance of this PKC-mediated GCl reduction for the function of muscles, this study explored effects of GCl reductions on contractile endurance in isolated rat muscles. Contractile endurance was assessed from the ability of muscle to maintain force during prolonged stimulation under conditions when GCl was manipulated by: (i) inhibition of PKC, (ii) reduction of solution Cl− or (iii) inhibition of ClC-1 Cl− channels using 9-anthracene-carboxylic acid (9-AC). Experiments showed that contractile endurance was optimally preserved by reductions in GCl similar to what occurs in active muscle. Contrastingly, further GCl reductions compromised the endurance. The experiments thus show a biphasic relationship between GCl and contractile endurance in which partial GCl reduction improves endurance while further GCl reduction compromises endurance. Intracellular recordings of trains of action potentials suggest that this biphasic dependency of contractile endurance on GCl reflects that lowering GCl enhances muscle excitability but low GCl also increases the depolarisation of muscle fibres during excitation and reduces their ability to re-accumulate K+ lost during excitation. If GCl becomes very low, the latter actions dominate causing reduced endurance. It is concluded that the PKC-mediated ClC-1 channel inhibition in active muscle reduces GCl to a level that optimises contractile endurance during intense exercise. PMID:23045345
van Saase, J L; Noteboom, W M; Vandenbroucke, J P
OBJECTIVE--To compare the long term survival of a group of athletes taking prolonged vigorous physical exercise to that of the general population. DESIGN--Follow up of a cohort of participants in the Dutch eleven cities ice skating tour (a race and recreational tour) over a distance of 200 kilometers. SETTING--Data on participation from the organising committee and data on mortality from all municipalities in The Netherlands. SUBJECTS--2259 Male athletes. MAIN OUTCOME MEASURES--Comparison of all cause mortality in male participants in the tour with that in the general population of The Netherlands. RESULTS--The standardised mortality ratio for all participants during 32 years of follow up was 0.76 (95% confidence interval 0.68 to 0.85), and 0.90 (0.48 to 1.44) for participants in the race, and 0.72 (0.60 to 0.86) for participants in the recreational tour who finished within the time limit. CONCLUSIONS--The capacity for prolonged and vigorous physical exercise, particularly if the exercise is recreational, is a strong indicator of longevity. Images p1409-a p1411-a PMID:2279154
Wilbanks, Mitchell S.; Gust, Kurt A.; Atwa, Sahar; Sunesara, Imran; Johnson, David; Ang, Choo Yaw; Meyer, Sharon A.; Perkins, Edward J.
2,4-dinitrotoluene (2,4-DNT) is a nitroaromatic used in industrial dyes and explosives manufacturing processes that is found as a contaminant in the environment. Previous studies have implicated antagonism of PPARα signaling as a principal process affected by 2,4-DNT. Here, we test the hypothesis that 2,4-DNT-induced perturbations in PPARα signaling and resultant downstream deficits in energy metabolism, especially from lipids, cause organism-level impacts on exercise endurance. PPAR nuclear activation bioassays demonstrated inhibition of PPARα signaling by 2,4-DNT whereas PPARγ signaling increased. PPARα (-/-) and wild-type (WT) female mice were exposed for 14 days to vehicle or 2,4-DNT (134 mg/kg/day) and performed a forced swim to exhaustion 1 day after the last dose. 2,4-DNT significantly decreased body weights and swim times in WTs, but effects were significantly mitigated in PPARα (-/-) mice. 2,4-DNT decreased transcript expression for genes downstream in the PPARα signaling pathway, principally genes involved in fatty acid transport. Results indicate that PPARγ signaling increased resulting in enhanced cycling of lipid and carbohydrate substrates into glycolytic/gluconeogenic pathways favoring energy production versus storage in 2,4-DNT-exposed WT and PPARα (-/-) mice. PPARα (-/-) mice appear to have compensated for the loss of PPARα by shifting energy metabolism to PPARα-independent pathways resulting in lower sensitivity to 2,4-DNT when compared with WT mice. Our results validate 2,4-DNT-induced perturbation of PPARα signaling as the molecular initiating event for impaired energy metabolism, weight loss, and decreased exercise performance. PMID:24893713
Oosthuyse, Tanja; Carstens, Matthew; Millen, Aletta M
Certain commercial carbohydrate replacement products include slowly absorbed carbohydrates such as isomaltulose. Few studies have investigated the metabolic effects of ingesting isomaltulose during exercise and none have evaluated exercise performance and gastrointestinal comfort. Nine male cyclists participated postprandially during three trials of 2-h steady-state (S-S) exercise (60%Wmax) followed by a 16 km time trial (TT) while ingesting 63 g·h-1 of either, 0.8:1 fructose: maltodextrin (F:M) or isomaltulose (ISO) or placebo- flavored water (PL). Data were analyzed by magnitude-based inferences. During S-S exercise, ISO and PL similarly increased plasma nonesterified fatty acid (NEFA) concentration (mean change ISO versus F:M: 0.18, 90%CI ±0.21 mmol·L-1, 88% likelihood) and fat oxidation (10, 90%CI ±9 g, 89% likelihood) while decreasing carbohydrate oxidation (-36, 90%CI ±30.2 g, 91% likelihood) compared with F:M, despite equal elevations in blood glucose concentration with ISO and F:M. Rating of stomach cramps and bloating increased progressively with ISO (rating: 0-90 min S-S, weak; 120 min S-S, moderate; TT, strong) compared with F:M and PL (0-120 min S-S and TT, very weak). TT performance was substantially slower with ISO (mean change: 1.5, 90%CI ±1.4 min, 94% likely harmful) compared with F:M. The metabolic response of ISO ingestion during moderate exercise to increase NEFA availability and fat oxidation despite elevating blood glucose concentration is anomalous for a carbohydrate supplement. However, ingesting isomaltulose at a continuous high frequency to meet the recommended carbohydrate replacement dose, results in severe gastrointestinal symptoms during prolonged or high intensity exercise and negatively affects exercise performance compared with fructose-maltodextrin supplementation.
Kim, Sang Hyun; Koh, Jin Ho; Higashida, Kazuhiko; Jung, Su Ryun; Holloszy, John O; Han, Dong-Ho
Endurance exercise training can increase the ability to perform prolonged strenuous exercise. The major adaptation responsible for this increase in endurance is an increase in muscle mitochondria. This adaptation occurs too slowly to provide a survival advantage when there is a sudden change in environment that necessitates prolonged exercise. In the present study, we discovered another, more rapid adaptation, a downregulation of expression of the glycogenolytic and glycolytic enzymes in muscle that mediates a slowing of muscle glycogen depletion and lactic acid accumulation. This adaptation, which appears to be mediated by PGC-1α, occurs in response to a single exercise bout and is further enhanced by two additional daily exercise bouts. It is biologically significant, because glycogen depletion and lactic acid accumulation are two of the major causes of muscle fatigue and exhaustion. PMID:25416622
Hinton, Pamela S
Iron is a trace mineral that is highly significant to endurance athletes. Iron is critical to optimal athletic performance because of its role in energy metabolism, oxygen transport, and acid-base balance. Endurance athletes are at increased risk for suboptimal iron status, with potential negative consequences on performance, because of the combination of increased iron needs and inadequate dietary intake. This review paper summarizes the role of iron in maximal and submaximal exercise and describes the effects of iron deficiency on exercise performance. Mechanisms that explain the increased risk of iron deficiency in endurance athletes, including exercise-associated inflammation and hepcidin release on iron sequestration, are described. Information on screening athletes for iron deficiency is presented, and suggestions to increase iron intake through diet modification or supplemental iron are provided.
King, James A; Garnham, Jack O; Jackson, Andrew P; Kelly, Benjamin M; Xenophontos, Soteris; Nimmo, Myra A
Exercise increases energy expenditure however acutely this does not cause compensatory changes in appetite or food intake. This unresponsiveness contrasts the rapid counter-regulatory changes seen after food restriction. The present investigation examined whether corrective changes in appetite-regulatory parameters occur after a time delay, namely, on the day after a single bout of exercise. Nine healthy males completed two, two-day trials (exercise & control) in a random order. On the exercise trial participants completed 90 min of moderate-intensity treadmill running on day one (10:30-12:00h). On day two appetite-regulatory hormones and subjective appetite perceptions were assessed frequently in response to two test meals provided at 08:00 and 12:00 h. Identical procedures occurred in the control trial except no exercise was performed on day one. Circulating levels of leptin were reduced on the day after exercise (AUC 5841 ± 3335 vs. 7266 ± 3949 ng(-1)·mL(-1)·7h, P=0.012). Conversely, no compensatory changes were seen for circulating acylated ghrelin, total PYY, insulin or appetite perceptions. Unexpectedly, levels of acylated ghrelin were reduced on the exercise trial following the second test meal on day two (AUC 279 ± 136 vs. 326 ± 136 pg(-1)·mL(-1)·3h, P=0.021). These findings indicate that short-term energy deficits induced by exercise initially prompt a compensatory response by chronic but not acute hormonal regulators of appetite and energy balance. Within this 24h time-frame however there is no conscious recognition of the perturbation to energy balance.
Backhouse, Susan H; Biddle, Stuart J H; Bishop, Nicolette C; Williams, Clyde
Caffeine's metabolic and performance effects have been widely reported. However, caffeine's effects on affective states during prolonged exercise are unknown. Therefore, this was examined in the present study. Following an overnight fast and in a randomised, double-blind, counterbalanced design, twelve endurance trained male cyclists performed 90 min of exercise at 70% VO(₂ max) 1h after ingesting 6 mg kg⁻¹ BM of caffeine (CAF) or placebo (PLA). Dimensions of affect and perceived exertion were assessed at regular intervals. During exercise, pleasure ratings were better maintained (F(₃,₃₈)=4.99, P < 0.05) in the CAF trial compared to the PLA trial with significantly higher ratings at 15, 30 and 75 min (all P < 0.05). Perceived exertion increased (F(₃,₃₈) = 19.86, P < 0.01) throughout exercise and values, overall, were significantly lower (F(₁,₁₁) = 9.26, P < 0.05) in the CAF trial compared to the PLA trial. Perceived arousal was elevated during exercise but did not differ between trials. Overall, the results suggest that a moderate dose of CAF ingested 1h prior to exercise maintains a more positive subjective experience during prolonged cycling. This observation may partially explain caffeine's ergogenic effects.
Penttinen, J; Erkkola, R
The purpose of the present study was to examine pregnancy and delivery among Finnish endurance athletes at the national top level. A questionnaire concerning first pregnancy was sent to 30 Finnish endurance athletes who had been at national top level in cross-country skiing, running, speed-skating or orienteering. Data on labour were collected retrospectively through a questionnaire and from the diaries in the hospital concerned. The next primipara in the diaries formed a member of the control group. Twenty-three athletes (77%) had regular menstrual cycles, seven (23%) had irregularities, and four of them had received hormonal treatment for this. Seven athletes (23%) had experienced spontaneous abortion during the first trimester in previous pregnancy. Sixteen (53%) did not notice any change in their exercise performance, three (10%) subjectively felt themselves to be in a better physical condition, and seven (23%) felt themselves to be in a worse condition than before the pregnancy. Four did not respond on the question. After delivery, 18 athletes continued to compete, the median interval being 8.2 months (range 2-24 months). Two of them (11%) achieved a better condition than before the pregnancy, 11 (61%) reached the same level and five (28%) did not achieve the same performance level. There were no significant differences in labour parameters between the athletes and controls. Endurance training had no harmful side-effects on the pregnancies or deliveries of the athletes. The effect of pregnancy on exercise performance is individual.
Carfagna, Simona; Napolitano, Gaetana; Barone, Daniela; Pinto, Gabriele; Venditti, Paola
We studied the effects of ten-day 1% Galdieria sulphuraria dietary supplementation on oxidative damage and metabolic changes elicited by acute exercise (6-hour swimming) determining oxygen consumption, lipid hydroperoxides, protein bound carbonyls in rat tissue (liver, heart, and muscle) homogenates and mitochondria, tissue glutathione peroxidase and glutathione reductase activities, glutathione content, and rates of H2O2 mitochondrial release. Exercise increased oxidative damage in tissues and mitochondria and decreased tissue content of reduced glutathione. Moreover, it increased State 4 and decreased State 3 respiration in tissues and mitochondria. G. sulphuraria supplementation reduced the above exercise-induced variations. Conversely, alga supplementation was not able to modify the exercise-induced increase in mitochondrial release rate of hydrogen peroxide and in liver and heart antioxidant enzyme activities. The alga capacity to reduce lipid oxidative damage without reducing mitochondrial H2O2 release can be due to its high content of C-phycocyanin and glutathione, which are able to scavenge peroxyl radicals and contribute to phospholipid hydroperoxide metabolism, respectively. In conclusion, G. sulphuraria ability to reduce exercise-linked oxidative damage and mitochondrial dysfunction makes it potentially useful even in other conditions leading to oxidative stress, including hyperthyroidism, chronic inflammation, and ischemia/reperfusion. PMID:25874021
Smith, Gordon I; Jeukendrup, Asker E; Ball, Derek
At rest, administration of the short-chain fatty acid acetate suppresses fat oxidation without affecting carbohydrate utilization. The combined effect of increased acetate availability and exercise on substrate utilization is, however, unclear. With local ethics approval, we studied the effect of ingesting either sodium acetate (NaAc) or sodium bicarbonate (NaHCO3) at a dose of 4 mmol·kg-1 body mass 90 min before completing 120 min of exercise at 50% VO2peak. Six healthy young men completed the trials after an overnight fast and ingested the sodium salts in randomized order. As expected NaAc ingestion decreased resting fat oxidation (mean ± SD; 0.09 ± 0.02 vs. 0.07 ± 0.02 g·min-1 pre- and post-ingestion respectively, p < .05) with no effect upon carbohydrate utilization. In contrast, NaHCO3 ingestion had no effect on substrate utilization at rest. In response to exercise, fat and CHO oxidation increased in both trials, but fat oxidation was lower (0.16 ± 0.10 vs. 0.29 ± 0.11 g·min-1, p < .05) and carbohydrate oxidation higher (1.67 ± 0.35 vs. 1.44 ± 0.22 g·min-1, p < .05) in the NaAc trial compared with the NaHCO3 trial during the first 15 min of exercise. Over the final 75 min of exercise an increase in fat oxidation and decrease in carbohydrate oxidation was observed only in the NaAc trial. These results demonstrate that increasing plasma acetate concentration suppresses fat oxidation both at rest and at the onset of moderate-intensity exercise.
Murphy, K T; Petersen, A C; Goodman, C; Gong, X; Leppik, J A; Garnham, A P; Cameron-Smith, D; Snow, R J; McKenna, M J
This study investigated effects of prolonged submaximal exercise on Na+-K+-ATPase mRNA and protein expression, maximal activity, and content in human skeletal muscle. We also investigated the effects on mRNA expression of the transcription initiator gene, RNA polymerase II (RNAP II), and key genes involved in protein translation, eukaryotic initiation factor-4E (eIF-4E) and 4E-binding protein 1 (4E-BP1). Eleven subjects (6 men, 5 women) cycled at 75.5% (SD 4.8%) peak O2 uptake and continued until fatigue. A vastus lateralis muscle biopsy was taken at rest, fatigue, and 3 and 24 h postexercise. We analyzed muscle for Na+-K+-ATPase alpha1, alpha2, alpha3, beta1, beta2, and beta3, as well for RNAP II, eIF-4E, and 4E-BP1 mRNA expression by real-time RT-PCR and Na+-K+-ATPase isoform protein abundance using immunoblotting. Muscle homogenate maximal Na+-K+-ATPase activity was determined by 3-O-methylfluorescein phosphatase activity and Na+-K+-ATPase content by [3H]ouabain binding. Cycling to fatigue [54.5 (SD 20.6) min] immediately increased alpha3 (P = 0.044) and beta2 mRNA (P = 0.042) by 2.2- and 1.9-fold, respectively, whereas alpha1 mRNA was elevated by 2.0-fold at 24 h postexercise (P = 0.036). A significant time main effect was found for alpha3 protein abundance (P = 0.046). Exercise transiently depressed maximal Na+-K+-ATPase activity (P = 0.004), but Na+-K+-ATPase content was unaltered throughout recovery. Exercise immediately increased RNAP II mRNA by 2.6-fold (P = 0.011) but had no effect on eIF-4E and 4E-BP1 mRNA. Thus a single bout of prolonged submaximal exercise induced isoform-specific Na+-K+-ATPase responses, increasing alpha1, alpha3, and beta2 mRNA but only alpha3 protein expression. Exercise also increased mRNA expression of RNAP II, a gene initiating transcription, but not of eIF-4E and 4E-BP1, key genes initiating protein translation.
Radel, Rémi; Brisswalter, Jeanick; Perrey, Stéphane
Executive functioning and attention require mental effort. In line with the resource conservation principle, we hypothesized that mental effort would be saved when individuals expected to exercise for a long period. Twenty-two study participants exercised twice on a cycle ergometer for 10 min at 60% of their maximal aerobic power, with the expectation of exercising for either 10 min or 60 min. Changes in activity in the right dorsolateral prefrontal cortex (rdlPFC) and right medial frontal cortex (rmPFC) were investigated by measuring oxyhemoglobin using near-infrared spectroscopy. Attentional focus and ratings of perceived exertion were assessed at three time points (200, 400, and 600 s). The oxyhemoglobin concentration was lower in the rdlPFC and higher in the rmPFC under the 60-min than under the 10-min condition. Also, attention was less focused in the 60-min than in the 10-min condition. We discuss these results as possible evidence of a disengagement of the brain regions associated with mental effort (executive network), in favor of brain regions linked to resting activity (the default network), in order to save mental resources for the maintenance of exercise.
Burdon, Catriona A; Ruell, Patricia; Johnson, Nathan; Chapman, Phillip; O'Brien, Sinead; O'Connor, Helen T
The aim of this study was to determine the effect of exercise in the heat on thermoregulatory responses and plasma vasoactive intestinal peptide concentration (VIP) and whether it is modulated by ice-slushy consumption. Ten male participants cycled at 62% V̇O2max for 90min in 32°C and 40% relative humidity. A thermoneutral (37°C) or ice-slushy (-1°C) sports drink was given at 3.5mlkg(-1) body mass every 15min during exercise. VIP and rectal temperature increased during exercise (mean±standard deviation: 4.6±4.4pmolL(-1), P=0.005; and 1.3±0.4°C, P<0.001 respectively) and were moderately associated (r=0.35, P=0.008). While rectal temperature and VIP were not different between trials, ice-slushy significantly reduced heat storage (P=0.010) and skin temperature (time×trial interaction P=0.038). It appears that VIP does not provide the signal linking cold beverage ingestion and lower skin temperature in the heat.
O'Hara, John P; Woods, David R; Mellor, Adrian; Boos, Christopher; Gallagher, Liam; Tsakirides, Costas; Arjomandkhah, Nicola C; Holdsworth, David A; Cooke, Carlton B; Morrison, Douglas J; Preston, Thomas; King, Roderick Fgj
This study compared the effects of coingesting glucose and fructose on exogenous and endogenous substrate oxidation during prolonged exercise at altitude and sea level, in men. Seven male British military personnel completed two bouts of cycling at the same relative workload (55% Wmax) for 120 min on acute exposure to altitude (3375 m) and at sea level (~113 m). In each trial, participants ingested 1.2 g·min(-1) of glucose (enriched with (13)C glucose) and 0.6 g·min(-1) of fructose (enriched with (13)C fructose) directly before and every 15 min during exercise. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total and exogenous carbohydrate oxidation, plasma glucose oxidation, and endogenous glucose oxidation derived from liver and muscle glycogen. Total carbohydrate oxidation during the exercise period was lower at altitude (157.7 ± 56.3 g) than sea level (286.5 ± 56.2 g, P = 0.006, ES = 2.28), whereas fat oxidation was higher at altitude (75.5 ± 26.8 g) than sea level (42.5 ± 21.3 g, P = 0.024, ES = 1.23). Peak exogenous carbohydrate oxidation was lower at altitude (1.13 ± 0.2 g·min(-1)) than sea level (1.42 ± 0.16 g·min(-1), P = 0.034, ES = 1.33). There were no differences in rates, or absolute and relative contributions of plasma or liver glucose oxidation between conditions during the second hour of exercise. However, absolute and relative contributions of muscle glycogen during the second hour were lower at altitude (29.3 ± 28.9 g, 16.6 ± 15.2%) than sea level (78.7 ± 5.2 g (P = 0.008, ES = 1.71), 37.7 ± 13.0% (P = 0.016, ES = 1.45). Acute exposure to altitude reduces the reliance on muscle glycogen and increases fat oxidation during prolonged cycling in men compared with sea level.
Philp, Andrew; Chen, Ai; Lan, Debin; Meyer, Gretchen A.; Murphy, Anne N.; Knapp, Amy E.; Olfert, I. Mark; McCurdy, Carrie E.; Marcotte, George R.; Hogan, Michael C.; Baar, Keith; Schenk, Simon
The protein deacetylase, sirtuin 1 (SIRT1), is a proposed master regulator of exercise-induced mitochondrial biogenesis in skeletal muscle, primarily via its ability to deacetylate and activate peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). To investigate regulation of mitochondrial biogenesis by SIRT1 in vivo, we generated mice lacking SIRT1 deacetylase activity in skeletal muscle (mKO). We hypothesized that deacetylation of PGC-1α and mitochondrial biogenesis in sedentary mice and after endurance exercise would be impaired in mKO mice. Skeletal muscle contractile characteristics were determined in extensor digitorum longus muscle ex vivo. Mitochondrial biogenesis was assessed after 20 days of voluntary wheel running by measuring electron transport chain protein content, enzyme activity, and mitochondrial DNA expression. PGC-1α expression, nuclear localization, acetylation, and interacting protein association were determined following an acute bout of treadmill exercise (AEX) using co-immunoprecipitation and immunoblotting. Contrary to our hypothesis, skeletal muscle endurance, electron transport chain activity, and voluntary wheel running-induced mitochondrial biogenesis were not impaired in mKO versus wild-type (WT) mice. Moreover, PGC-1α expression, nuclear translocation, activity, and deacetylation after AEX were similar in mKO versus WT mice. Alternatively, we made the novel observation that deacetylation of PGC-1α after AEX occurs in parallel with reduced nuclear abundance of the acetyltransferase, general control of amino-acid synthesis 5 (GCN5), as well as reduced association between GCN5 and nuclear PGC-1α. These findings demonstrate that SIRT1 deacetylase activity is not required for exercise-induced deacetylation of PGC-1α or mitochondrial biogenesis in skeletal muscle and suggest that changes in GCN5 acetyltransferase activity may be an important regulator of PGC-1α activity after exercise. PMID:21757760
Effectiveness of a portable, ice-pack cooling vest (Steelevest) in prolonging work tolerance time in chemical defense clothing in the heat (33 C dry bulb, 33% relative humidity or 25 C WBGT) was evaluated while subjects exercised at a metabolic rate of approx. 700 watts. Subjects were six male volunteers. The protocol consisted of a 20 minute treadmill walk at 1.33 m/s. and 7.5% grade, followed by 15 minutes of a lifting task, 5 minutes rest, then another 20 minutes of lifting task for a total of one hour. The lifting task consisted of lifting of 20 kg box, carrying it 3 meters and setting it down. This was followed by a 6 m walk (3m back to the start point and 3 m back to the box) 15 sec after which the lifting cycle began again. The work was classified as heavy as previously defined. This protocol was repeated until the subjects were unable to continue or they reached a physiological endpoint. Time to voluntary cessation or physiological endpoint was called the work tolerance time. Physiological endpoints were rectal temperature of 39 C, heart rate exceeding 95% of maximum for two consecutive minutes or visible loss of motor control or nausea. The cooling vest had no effect on work tolerance time, rate of rise of rectal temperature or sweat loss. It was concluded that the Steelvest ice-vest is ineffective in prolonging work tolerance time and preventing increases in rectal temperature while wearing chemical protective clothing.
Viggiani, Daniel; Callaghan, Jack P
Persons who develop low back pain from prolonged standing exhibit increased muscle cocontraction, decreased movement and increased spine extension. However, it is unclear how these factors relate to pain development. The purpose of this study was to use hip abductor fatigue to manipulate muscle activity patterns and determine its effects on standing behaviours and pain development. Forty participants stood for two hours twice, once following a hip abductor fatigue exercise (fatigue), and once without exercise beforehand (control). Trunk and gluteal muscle activity were measured to determine cocontraction. Lumbo-pelvic angles and force plates were used to assess posture and movement strategies. Visual analog scales differentiated pain (PDs) and non-pain developers (NPDs). PDs reported less low back pain during the fatigue session, with females having earlier reductions of similar scale than males. The fatigue session reduced gluteal and trunk cocontraction and increased centre of pressure movement; male and female PDs had opposing spine posture compensations. Muscle fatigue prior to standing reduced cocontraction, increased movement during standing and reduced the low back pain developed by PDs; the timing of pain reductions depended on spine postures adopted during standing.
Di Filippo, C; Trotta, M C; Maisto, R; Siniscalco, D; Luongo, M; Mascolo, L; Alfano, R; Accardo, M; Rossi, C; Ferraraccio, F; D'Amico, M
Rats receiving daily intraperitoneal administration of O2 and running on a treadmill covered an average distance of 482.8 ± 21.8 m/week as calculated during 5-week observation. This distance was increased in rats receiving daily intraperitoneal administration of an oxygen/O3 mixture at a dose of 100; 150; and 300 μg/kg with the maximum increase being +34.5% at 300 μg/kg and still present after stopping the administration of oxygen/O3. Oxygen/O3 decreased the mean arterial blood pressure (-13%), the heart rate (-6%), the gastrocnemius and cardiac hypertrophy, and fibrosis and reduced by 49% the left ventricular mass and relative wall thickness measurements. Systolic and diastolic functions were improved in exercised oxygen/O3 rats compared to O2 rats. Oxygen/O3 treatment led to higher MPI index starting from the dose of 150 μg/kg (p < 0.05) and more effective (+14%) at a dose of 300 μg/kg oxygen/O3. Oxygen/O3 dose-dependently increased the expression of the antioxidant enzymes Mn-SOD and GPx1 and of eNOS compared to the exercised O2 rats. The same doses resulted in decrease of LDH levels, CPK, TnI, and nitrotyrosine concentration in the heart and gastrocnemius tissues, arguing a beneficial effect of the ozone molecule against the fatigue induced by a prolonged high intensity exercise.
Paluska, Scott A
Caffeine is the most commonly consumed drug in the world, and athletes frequently use it as an ergogenic aid. It improves performance and endurance during prolonged, exhaustive exercise. To a lesser degree it also enhances short-term, high-intensity athletic performance. Caffeine improves concentration, reduces fatigue, and enhances alertness. Habitual intake does not diminish caffeine's ergogenic properties. Several mechanisms have been proposed to explain the physiologic effects of caffeine, but adenosine receptor antagonism most likely accounts for the primary mode of action. It is relatively safe and has no known negative performance effects, nor does it cause significant dehydration or electrolyte imbalance during exercise. Routine caffeine consumption may cause tolerance or dependence, and abrupt discontinuation produces irritability, mood shifts, headache, drowsiness, or fatigue. Major sport governing bodies ban excessive use of caffeine, but current monitoring techniques are inadequate, and ethical dilemmas persist regarding caffeine intake by athletes.
Schiphof-Godart, Lieke; Hettinga, Florentina J.
Endurance sports are booming, with sports passionates of varying skills and expertise battering city streets and back roads on their weekly or daily exercise rounds. The investments required for performing in endurance exercise are nevertheless considerable, and passion for their sport might explain the efforts endurance athletes are willing to make. Passion may be defined as a strong motivational force and as such might be related to the neurophysiological basis underlying the drive to exercise. A complex relationship between the brain and other systems is responsible for athletes' exercise behavior and thus performance in sports. We anticipate important consequences of athletes' short term choices, for example concerning risk taking actions, on long term outcomes, such as injuries, overtraining and burnout. We propose to consider athletes' type of passion, in combination with neurophysiological parameters, as an explanatory factor inunderstanding the apparent disparity in the regulation of exercise intensity during endurance sports. Previous research has demonstrated that athletes can be passionate toward their sport in either a harmonious or an obsessive way. Although both lead to considerable investments and therefore often to successful performances, obsessive passion may affect athlete well-being and performance on the long run, due to the corresponding inflexible exercise behavior. In this perspective we will thus examine the influence of passion in sport on athletes' short term and long term decision-making and exercise behavior, in particular related to the regulation of exercise intensity, and discuss the expected long term effects of both types of passion for sport. PMID:28265245
Cosca, David D; Navazio, Franco
Endurance athletes alternate periods of intensive physical training with periods of rest and recovery to improve performance. An imbalance caused by overly intensive training and inadequate recovery leads to a breakdown in tissue reparative mechanisms and eventually to overuse injuries. Tendon overuse injury is degenerative rather than inflammatory. Tendinopathy is often slow to resolve and responds inconsistently to anti-inflammatory agents. Common overuse injuries in runners and other endurance athletes include patellofemoral pain syndrome, iliotibial band friction syndrome, medial tibial stress syndrome, Achilles tendinopathy, plantar fasciitis, and lower extremity stress fractures. These injuries are treated with relative rest, usually accompanied by a rehabilitative exercise program. Cyclists may benefit from evaluation on their bicycles and subsequent adjustment of seat height, cycling position, or pedal system. Endurance athletes also are susceptible to exercise-associated medical conditions, including exercise-induced asthma, exercise-associated collapse, and overtraining syndrome. These conditions are treatable or preventable with appropriate medical intervention. Dilutional hyponatremia is increasingly encountered in athletes participating in marathons and triathlons. This condition is related to overhydration with hypotonic fluids and may be preventable with guidance on appropriate fluid intake during competition.
Cywińska, Anna; Szarska, Ewa; Górecka, Renata; Witkowski, Lucjan; Hecold, Mateusz; Bereznowski, Andrzej; Schollenberger, Antoni; Winnicka, Anna
Acute phase proteins (APP) have been described as useful for assessing health in human and animal patients, as they closely reflect the acute phase reaction (APR). In humans and dogs a reaction analogous to APR has also been described after prolonged or strenuous exercise. The aim of this study was to determine, if similar reactions occur in endurance horses after limited and long distance rides. Seventeen horses that successfully completed various distance competitions were tested. Routine haematological and biochemical tests were performed and the concentrations of serum amyloid A (SAA), C-reactive protein (CRP) and haptoglobin were measured. Typical endurance exercise-induced haematological and biochemical changes were observed in all horses, regardless the distance. After long distance rides, the level of SAA markedly increased, but CRP and haptoglobin concentrations remained unchanged. After limited distance rides no changes in the levels of APPs were noted. Exercise-induced APR in horses occurred only after prolonged, strenuous exertion, and differed from APR in inflammation in that only SAA concentration was increased.
Henríquez-Olguín, Carlos; Andrade, David Cristóbal; Ramírez-Campillo, Rodrigo; White, Allan; Cerda-Kohler, Hugo
The aim of the present study was to determine the effects of three weeks of hyperbaric oxygen (HBO2) training on oxidative stress markers and endurance performance in young soccer players. Participants (18.6 ± 1.6 years) were randomized into hyperbaric-hyperoxic (HH) training (n = 6) and normobaric normoxic (NN) training (n = 6) groups. Immediately before and after the 5th, 10th, and 15th training sessions, plasma oxidative stress markers (lipid hydroperoxides and uric acid), plasma antioxidant capacity (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid [TROLOX]), arterial blood gases, acid-base balance, bases excess (BE), and blood lactate analyses were performed. Before and after intervention, maximal oxygen uptake (VO2max) and peak power output (PPO) were determined. Neither HH nor NN experienced significant changes on oxidative stress markers or antioxidant capacity during intervention. VO2max and PPO were improved (moderate effect size) after HH training. The results suggest that HBO2 endurance training does not increase oxidative stress markers and improves endurance performance in young soccer players. Our findings warrant future investigation to corroborate that HBO2 endurance training could be a potential training approach for highly competitive young soccer players. PMID:28083148
Burgos, Carlos; Henríquez-Olguín, Carlos; Andrade, David Cristóbal; Ramírez-Campillo, Rodrigo; Araneda, Oscar F; White, Allan; Cerda-Kohler, Hugo
The aim of the present study was to determine the effects of three weeks of hyperbaric oxygen (HBO2) training on oxidative stress markers and endurance performance in young soccer players. Participants (18.6 ± 1.6 years) were randomized into hyperbaric-hyperoxic (HH) training (n = 6) and normobaric normoxic (NN) training (n = 6) groups. Immediately before and after the 5th, 10th, and 15th training sessions, plasma oxidative stress markers (lipid hydroperoxides and uric acid), plasma antioxidant capacity (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid [TROLOX]), arterial blood gases, acid-base balance, bases excess (BE), and blood lactate analyses were performed. Before and after intervention, maximal oxygen uptake (VO2max) and peak power output (PPO) were determined. Neither HH nor NN experienced significant changes on oxidative stress markers or antioxidant capacity during intervention. VO2max and PPO were improved (moderate effect size) after HH training. The results suggest that HBO2 endurance training does not increase oxidative stress markers and improves endurance performance in young soccer players. Our findings warrant future investigation to corroborate that HBO2 endurance training could be a potential training approach for highly competitive young soccer players.
Currie, Katharine D; Rosen, Lee M; Millar, Philip J; McKelvie, Robert S; MacDonald, Maureen J
Decreased heart rate variability and attenuated heart rate recovery following exercise are associated with an increased risk of mortality in cardiac patients. This study investigated the effects of 12 weeks of moderate-intensity endurance exercise (END) and a novel low-volume high-intensity interval exercise protocol (HIT) on measures of heart rate recovery and heart rate variability in patients with coronary artery disease (CAD). Fourteen males with CAD participated in 12 weeks of END or HIT training, each consisting of 2 supervised exercise sessions per week. END consisted of 30-50 min of continuous cycling at 60% peak power output (PPO). HIT involved ten 1-min intervals at 88% PPO separated by 1-min intervals at 10% PPO. Heart rate recovery at 1 min and 2 min was measured before and after training (pre- and post-training, respectively) using a submaximal exercise bout. Resting time and spectral and nonlinear domain measures of heart rate variability were calculated. Following 12 weeks of END and HIT, there was no change in heart rate recovery at 1 min (END, 40 ± 12 beats·min(-1) vs. 37 ± 19 beats·min(-1); HIT, 31 ± 8 beats·min(-1) vs. 35 ± 8 beats·min(-1); p ≥ 0.05 for pre- vs. post-training) or 2 min (END, 44 ± 18 beats·min(-1) vs. 43 ± 19 beats·min(-1); HIT, 42 ± 10 beats·min(-1) vs. 50 ± 6 beats·min(-1); p ≥ 0.05 for pre- vs. post-training). All heart rate variability indices were unchanged following END and HIT training. In conclusion, neither END nor HIT exercise programs elicited training-induced improvements in cardiac autonomic function in patients with CAD. The absence of improvements with training may be attributed to the optimal medical management and normative pretraining state of our sample.
Convertino, Victor A.
A number of past and most recent research findings that describe some of the physiological responses to exercise in man and their relationship with exposure to various gravitational environments are discussed. Most of the data pertain to adaptations of the cardiovascular and body fluid systems. It should be kept in mind that the data from studies on microgravity simulation in man include exposures of relatively short duration (5 hours to 14 days). However, it is argued that the results may provide important guidelines for the consideration of many variables which are pertinent to the development of exercise prescription for long-duration space flight. The following considerations for exercise prescriptions during long-duration space flight are noted: (1) Relatively high aerobic fitness and strength, especially of the upper body musculature, should be a criterion for selection of astronauts who will be involved in EVA, since endurance and strength appear to be predominant characteristics for work performance. (2) Some degree of upper body strength will probably be required for effective performance of EVA. However, the endurance and strength required by the upper body for EVA can probably be obtained through preflight exercise prescription which involves swimming. (3) Although some degree of arm exercise may be required to maintain preflight endurance and strength, researchers propose that regular EVA will probably be sufficient to maintain the endurance and strength required to effectively perform work tasks during space flight. (4) A minimum of one maximal aerobic exercise every 7 to 10 days during space flight may be all that is necessary for maintenance of normal cardiovascular responsiveness and replacement of body fluids for reentry following prolonged space flight. (5) The possible reduction in the amount of exercise required for maintenance of cardiovascular system and body fluids in combination with the use of electromyostimulation (EMS) or methods other
This article reviews the principles of feeding management for endurance horses. The amount and type of dietary energy (calories) are key considerations in dietary management, because (1) there is evidence that the body condition score, an indicator of overall energy balance, influences endurance exercise performance, and (2) the source of dietary energy (ie, carbohydrate versus fat calories) impacts health, metabolism, and athletic performance. Optimal performance is also dependent on provision of adequate feed, water, and electrolytes on race day.
Wallace, Marita A; Hock, M Benjamin; Hazen, Bethany C; Kralli, Anastasia; Snow, Rod J; Russell, Aaron P
The striated muscle activator of Rho signalling (STARS) is an actin-binding protein specifically expressed in cardiac, skeletal and smooth muscle. STARS has been suggested to provide an important link between the transduction of external stress signals to intracellular signalling pathways controlling genes involved in the maintenance of muscle function. The aims of this study were firstly, to establish if STARS, as well as members of its downstream signalling pathway, are upregulated following acute endurance cycling exercise; and secondly, to determine if STARS is a transcriptional target of peroxisome proliferator-activated receptor gamma co-activator 1-α (PGC-1α) and oestrogen-related receptor-α (ERRα). When measured 3 h post-exercise, STARS mRNA and protein levels as well as MRTF-A and serum response factor (SRF) nuclear protein content, were significantly increased by 140, 40, 40 and 40%, respectively. Known SRF target genes, carnitine palmitoyltransferase-1β (CPT-1β) and jun B proto-oncogene (JUNB), as well as the exercise-responsive genes PGC-1α mRNA and ERRα were increased by 2.3-, 1.8-, 4.5- and 2.7-fold, 3 h post-exercise. Infection of C2C12 myotubes with an adenovirus-expressing human PGC-1α resulted in a 3-fold increase in Stars mRNA, a response that was abolished following the suppression of endogenous ERRα. Over-expression of PGC-1α also increased Cpt-1β, Cox4 and Vegf mRNA by 6.2-, 2.0- and 2.0-fold, respectively. Suppression of endogenous STARS reduced basal Cpt-1β levels by 8.2-fold and inhibited the PGC-1α-induced increase in Cpt-1β mRNA. Our results show for the first time that the STARS signalling pathway is upregulated in response to acute endurance exercise. Additionally, we show in C2C12 myotubes that the STARS gene is a PGC-1α/ERRα transcriptional target. Furthermore, our results suggest a novel role of STARS in the co-ordination of PGC-1α-induced upregulation of the fat oxidative gene, CPT-1β.
Vogelsang, T W; Hanel, B; Kristoffersen, U S; Petersen, C L; Mehlsen, J; Holmquist, N; Larsson, B; Kjaer, A
The aim of the present investigation was to examine how 8 weeks of intense endurance training influenced right and left ventricular volumes and mass in obese untrained subjects. Ten overweight subjects (19-47 years; body mass index of 34+/-5 kg/m(2)) underwent intensive endurance training (rowing) three times 30 min/week for 8 weeks at a relative intensity of 72+/-8% of their maximal heart rate response (mean+/-SD). Before and after 8 weeks of endurance training, the left and the right end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), stroke volume (SV) and ventricular mass (VM) were measured by Magnetic resonance imaging (MRI). Submaximal heart rate decreased from 126+/-5 to 113+/-3 b.p.m. (10%; P<0.01), and from 155+/-5 to 141+/-4 b.p.m. (9%; P<0.001) at submaximal workloads of 70 and 140 W (110 W for women), respectively (mean+/-SEM). Resting ventricular parameters increased significantly: left ventricular SV, EDV and VM increased by 6%, 7% and 13%, respectively (P<0.01). The right side of the heart showed significant changes in SV, EDV and VM with increase of 4%, 4% and 12%, respectively (P<0.05). Eight weeks of endurance training significantly increased left ventricular SV and right ventricular SV, due to an increase in left ventricular EDV and right ventricular EDV. Furthermore, left VM and right VM increased. We conclude that using MRI and a longitudinal design it was possible to demonstrate similar and balanced changes in the right and left ventricle in response to training.
Moore, Daniel R; Camera, Donny M; Areta, Jose L; Hawley, John A
Recovery from the demands of daily training is an essential element of a scientifically based periodized program whose twin goals are to maximize training adaptation and enhance performance. Prolonged endurance training sessions induce substantial metabolic perturbations in skeletal muscle, including the depletion of endogenous fuels and damage/disruption to muscle and body proteins. Therefore, increasing nutrient availability (i.e., carbohydrate and protein) in the post-training recovery period is important to replenish substrate stores and facilitate repair and remodelling of skeletal muscle. It is well accepted that protein ingestion following resistance-based exercise increases rates of skeletal muscle protein synthesis and potentiates gains in muscle mass and strength. To date, however, little attention has focused on the ability of dietary protein to enhance skeletal muscle remodelling and stimulate adaptations that promote an endurance phenotype. The purpose of this review is to critically discuss the results of recent studies that have examined the role of dietary protein for the endurance athlete. Our primary aim is to consider the results from contemporary investigations that have advanced our knowledge of how the manipulation of dietary protein (i.e., amount, type, and timing of ingestion) can facilitate muscle remodelling by promoting muscle protein synthesis. We focus on the role of protein in facilitating optimal recovery from, and promoting adaptations to strenuous endurance-based training.
Schürch, P M
Fasting, or zero calorie diets are used not only by overweight people as a means of losing weight, but by athletes too. Their use is then explained on philosophical grounds, with the aim of even enhancing sports performance. The purpose of this investigation consisted of quantifying the effects of a 10-day fast on maximum performance capacity and endurance (as measured on a bicycle ergometer) of 12 female students of physical education of normal weight. The measurements included resting and exercise metabolism determinants, as well as weight and lean body mass. The main results show that after the diet period the maximum ergometric performance was lower in absolute terms as well as in relation to weight or lean body mass. Performance capacity for submaximal exercise was also reduced. Fat combustion was enhanced both at rest and during exercise. The reduction of maximum performance and endurance capacity may be explained by an enhanced muscle breakdown, an efficiency drop of muscular work, and an inadequate glycogen content of the acting muscles. Shorter fasting periods of 24-36 hours also lead to a lower performance level for exercise bouts extending from several minutes to 1-3 hours. An enhancement of fat combustion was always conspicuous. One may conclude that optimal physical performance is dependent on full hepatic and muscle glycogen stores. Glycogen concentration in the liver decreases sharply as a matter of fact after merely one day of carbohydrate shortage. Zero calorie or low carbohydrate diets are thus at variance with an optimal physical work capacity.
Billman, George E; Kukielka, Monica
Low heart rate variability (HRV) is associated with an increased susceptibility to ventricular fibrillation (VF). Exercise training can increase HRV (an index of cardiac vagal regulation) and could, thereby, decrease the risk for VF. To test this hypothesis, a 2-min coronary occlusion was made during the last min of a 18-min submaximal exercise test in dogs with healed myocardial infarctions; 20 had VF (susceptible), and 13 did not (resistant). The dogs then received either a 10-wk exercise program (susceptible, n=9; resistant, n=8) or an equivalent sedentary period (susceptible, n=11; resistant, n=5). HRV was evaluated at rest, during exercise, and during a 2-min occlusion at rest and before and after the 10-wk period. Pretraining, the occlusion provoked significantly (P<0.01) greater increases in HR (susceptible, 54.9+/-8.3 vs. resistant, 25.0+/-6.1 beats/min) and greater reductions in HRV (susceptible, -6.3+/-0.3 vs. resistant, -2.8+/-0.8 ln ms2) in the susceptible dogs compared with the resistant animals. Similar response differences between susceptible and resistant dogs were noted during submaximal exercise. Training significantly reduced the HR and HRV responses to the occlusion (HR, 17.9+/-11.5 beats/min; HRV, -1.2+/-0.8, ln ms2) in the susceptible dogs; similar response reductions were noted during exercise. In contrast, these variables were not altered in the sedentary susceptible dogs. Posttraining, VF could no longer be induced in the susceptible dogs, whereas four sedentary susceptible dogs died during the 10-wk control period, and the remaining seven animals still had VF when tested. Atropine decreased HRV but only induced VF in one of eight trained susceptible dogs. Thus exercise training increased cardiac vagal activity, which was not solely responsible for the training-induced VF protection.
Oosthuyse, Tanja; Millen, Aletta M E
Cardiac function is often suppressed following prolonged strenuous exercise and this may occur partly because of an energy deficit. This study compared left ventricular (LV) function by 2-dimensional echocardiography and tissue Doppler imaging (TDI) before and after ∼2.5 h of cycling (2-h steady-state 60% peak aerobic power output plus 16 km time trial) in 8 male cyclists when they ingested either placebo, carbohydrate-only (CHO-only), carbohydrate-casein hydrolysate (CHO-casein), or carbohydrate-whey hydrolysate (CHO-whey). No treatment-by-time interactions occurred, but pre-to-postexercise time effects occurred selectively. Although diastolic function measured by pulsed-wave Doppler early-to-late (E/A) transmitral blood flow velocity was suppressed in all trials from pre- to postexercise (mean change post-pre exercise: -0.53 (95% CI -0.15 to -0.91)), TDI early-to-late (e'/a') tissue velocity was significantly suppressed pre- to postexercise only with placebo, CHO-only, and CHO-whey (septal and lateral wall e'/a' average change: -0.62 (95% CI -1.12 to -0.12); -0.69 (95% CI -1.19 to -0.20); and -0.79 (95% CI -1.28 to -0.29), respectively) but not with CHO-casein (-0.40 (95% CI -0.90 to 0.09)). LV contractility was, or tended to be, significantly reduced pre- to postexercise with placebo, CHO-only, and CHO-whey (systolic blood pressure/end systolic volume change, mm Hg·mL(-1): -0.8 (95% CI -1.2 to -0.4), p = 0.0003; -0.5 (95% CI -0.9 to -0.02), p = 0.035; and -0.4 (95% CI -0.8 to 0.04), p = 0.086, respectively), but not with CHO-casein (-0.3 (95% CI -0.8 to 0.1), p = 0.22). However, ejection fraction (EF) and ventricular-arterial coupling were significantly reduced pre- to postexercise only with placebo (placebo change: EF, -4.6 (95% CI -8.4 to -0.7)%; stroke volume/end systolic volume, -0.3 (95% CI -0.6 to -0.04)). Despite no treatment-by-time interactions, pre-to-postexercise time effects observed with specific beverages may be meaningful for athletes
Kumagai, S; Kai, Y; Hanada, H; Uezono, K; Sasaki, H
The purpose of the present study was to investigate the relationships among the resting systolic (SBP) and diastolic blood pressure (DBP) or SBP response during exercise with insulin resistance evaluated by a homeostasis model (HOMA-IR), abdominal fat accumulation (visceral fat area [VFA], subcutaneous fat area [SFA]) by computed tomography (CT), and an estimation of the maximal oxygen uptake (V*O2max) in 63 Japanese middle-aged male patients with type 2 diabetes mellitus (type 2 DM). Body mass index (BMI) and waist-to-hip ratio (WHR) in type 2 DM subjects were significantly higher than in age-matched healthy male control subjects (n = 135) with normal glucose tolerance. Resting SBP (127.7 +/- 16.2 mm Hg v 119.4 +/- 13.0 mm Hg) and DBP (82.2 +/- 11.9mmHg v 76.8 +/- 9.4 mm Hg) levels, and the percentage of hypertension (20.6% v 1.5%) in type 2 DM subjects were significantly higher than in the control subjects (P <.05). According to a multiple regression analysis for resting blood pressure in type 2 DM, VFA was found to be an independent predictor of SBP, while V*O2max and HOMA-IR were independent predictors of DBP. In the controls, however, HOMA-IR was not found to be a significantly independent predictor for either resting SBP or resting DBP. Measurement of the SBP response during graded exercise using a ramp test was performed by an electrical braked cycle ergometer in 54 patients with type 2 DM only. The SBP was measured at 15-second intervals during exercise. The exercise intensity at the double product breaking point (DPBP), which strongly correlated with the exercise intensity at the lactate threshold, was used as an index for the SBP response to standardized exercise intensity. The SBP corresponding to exercise intensity at DPBP (SBP@DPBP) was evaluated as an index of the SBP response to standardized exercise intensity. The change in SBP (deltaSBP = SBP@DPBP - resting SBP) was significantly and positively associated with log area under the curve for glucose
Place, Nicolas; Ivarsson, Niklas; Venckunas, Tomas; Neyroud, Daria; Brazaitis, Marius; Cheng, Arthur J; Ochala, Julien; Kamandulis, Sigitas; Girard, Sebastien; Volungevičius, Gintautas; Paužas, Henrikas; Mekideche, Abdelhafid; Kayser, Bengt; Martinez-Redondo, Vicente; Ruas, Jorge L; Bruton, Joseph; Truffert, Andre; Lanner, Johanna T; Skurvydas, Albertas; Westerblad, Håkan
High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca(2+) release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca(2+) leak at rest, and depressed force production due to impaired SR Ca(2+) release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca(2+)-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group.
Place, Nicolas; Ivarsson, Niklas; Venckunas, Tomas; Neyroud, Daria; Brazaitis, Marius; Cheng, Arthur J.; Ochala, Julien; Kamandulis, Sigitas; Girard, Sebastien; Volungevičius, Gintautas; Paužas, Henrikas; Mekideche, Abdelhafid; Kayser, Bengt; Martinez-Redondo, Vicente; Bruton, Joseph; Truffert, Andre; Lanner, Johanna T.; Skurvydas, Albertas; Westerblad, Håkan
High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca2+ release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca2+ leak at rest, and depressed force production due to impaired SR Ca2+ release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca2+-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group. PMID:26575622
Yamane, Motoi; Teruya, Hiroyasu; Nakano, Masataka; Ogai, Ryuji; Ohnishi, Norikazu; Kosaka, Mitsuo
The influence of regular post-exercise cold application to exercised muscles trained by ergometer cycling (leg muscles) or handgrip exercise using a weight-loaded handgrip ergometer (forearm flexor muscles) was studied in human volunteers. Muscle loads were applied during exercise programs three to four times a week for 4-6 weeks. Besides measuring parameters characterizing muscle performance, femoral and brachial artery diameters were determined ultrasonographically. Training effects were identified by comparing pre- and post-training parameters in matched groups separately for the trained limbs cooled after exercise by cold-water immersion and the corresponding trained limbs kept at room temperature. Significant training effects were three times more frequent in the control than in the cold group, including increases in artery diameters in the control but not in the cold group. It is concluded that training-induced molecular and humoral adjustments, including muscle hyperthermia, are physiological, transient and essential for training effects (myofiber regeneration, muscle hypertrophy and improved blood supply). Cooling generally attenuates these temperature-dependent processes and, in particular, hyperthermia-induced HSP formation. This seems disadvantageous for training, in contrast to the beneficial combination of rest, ice, compression and elevation in the treatment of macroscopic musculo-tendinous damage.
Cermak, Naomi M; van Loon, Luc J C
Carbohydrate and fat are the two primary fuel sources oxidized by skeletal muscle tissue during prolonged (endurance-type) exercise. The relative contribution of these fuel sources largely depends on the exercise intensity and duration, with a greater contribution from carbohydrate as exercise intensity is increased. Consequently, endurance performance and endurance capacity are largely dictated by endogenous carbohydrate availability. As such, improving carbohydrate availability during prolonged exercise through carbohydrate ingestion has dominated the field of sports nutrition research. As a result, it has been well-established that carbohydrate ingestion during prolonged (>2 h) moderate-to-high intensity exercise can significantly improve endurance performance. Although the precise mechanism(s) responsible for the ergogenic effects are still unclear, they are likely related to the sparing of skeletal muscle glycogen, prevention of liver glycogen depletion and subsequent development of hypoglycemia, and/or allowing high rates of carbohydrate oxidation. Currently, for prolonged exercise lasting 2-3 h, athletes are advised to ingest carbohydrates at a rate of 60 g·h⁻¹ (~1.0-1.1 g·min⁻¹) to allow for maximal exogenous glucose oxidation rates. However, well-trained endurance athletes competing longer than 2.5 h can metabolize carbohydrate up to 90 g·h⁻¹ (~1.5-1.8 g·min⁻¹) provided that multiple transportable carbohydrates are ingested (e.g. 1.2 g·min⁻¹ glucose plus 0.6 g·min⁻¹ of fructose). Surprisingly, small amounts of carbohydrate ingestion during exercise may also enhance the performance of shorter (45-60 min), more intense (>75 % peak oxygen uptake; VO(₂peak)) exercise bouts, despite the fact that endogenous carbohydrate stores are unlikely to be limiting. The mechanism(s) responsible for such ergogenic properties of carbohydrate ingestion during short, more intense exercise bouts has been suggested to reside in the central nervous
Background The purpose of this study was to determine the effects of the pre-workout supplement Assault™ (MusclePharm, Denver, CO, USA) on upper and lower body muscular endurance, aerobic and anaerobic capacity, and choice reaction time in recreationally-trained males. Subjective feelings of energy, fatigue, alertness, and focus were measured to examine associations between psychological factors and human performance. Methods Twelve recreationally-trained males participated in a 3-week investigation (mean +/- SD, age: 28 +/- 5 y, height: 178 +/- 9 cm, weight: 79.2 +/- 15.7 kg, VO2max: 45.7 +/- 7.6 ml/kg/min). Subjects reported to the human performance laboratory on three separate occasions. All participants completed a baseline/familiarization day of testing that included a maximal graded exercise test for the determination of aerobic capacity (VO2max), one-rep maximum (1-RM) for bench and leg press to determine 75% of 1-RM, choice reaction tests, and intermittent critical velocity familiarization. Choice reaction tests included the following: single-step audio and visual, one-tower stationary protocol, two-tower lateral protocol, three-tower multi-directional protocol, and three-tower multi-directional protocol with martial arts sticks. Subjects were randomly assigned to ingest either the supplement (SUP) or the placebo (PL) during Visit 2. Subjects were provided with the cross-over treatment on the last testing visit. Testing occurred 20 min following ingestion of both treatments. Results Significant (p < 0.05) main effects for the SUP were observed for leg press (SUP: 13 ± 6 reps, PL: 11 ± 3 reps), perceived energy (SUP: 3.4 ± 0.9, PL: 3.1 ± 0.8), alertness (SUP: 4.0 ± 0.7, PL: 3.5 ± 0.8), focus (SUP: 4.1 ± 0.6, PL: 3.5 ± 0.8), choice reaction audio single-step (SUP: 0.92 ± 0.10 s, PL: 0.97 ± 0.11 s), choice reaction multi-direction 15 s (SUP: 1.07 ± 0.12 s, PL: 1.13 ± 0.14 s), and multi-direction for 30 s (SUP: 1.10 ± 0.11 s, PL: 1.14 ± 0.13 s
Peinado, Ana B; Rojo-Tirado, Miguel A; Benito, Pedro J
Muscle glycogen, the predominant form of stored glucose in the body, and blood glucose are the main energy substrates for muscle contraction during exercise. Sucrose is an ideal substance for athletes to incorporate because it provides both glucose and fructose. Therefore, it is essential that athletes monitor their diet to maintain and increase muscle glycogen deposits, since they are a major limiting factor of prolonged exercise performance. Carbohydrate-rich diets are also recommended for endurance and ultra-endurance exercise, because they are associated with increased muscle glycogen stores, as well as delayed onset of fatigue. In addition, high carbohydrate diets and carbohydrate intake before and during exercise have shown to be beneficial due to increased concentrations of hepatic glycogen and maintenance of blood glucose. The effect of carbohydrate intake on athletic performance mainly depends on the characteristics of the exercise, the type and amount of carbohydrate ingested and the time of intake. A combination of these factors must be taken into account when analysing individual athletic performance.
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Vangelakoudi, A; Vogiatzis, I; Geladas, N
Laser sailors have to tolerate fatiguing contractions of the lower-body muscles for prolonged periods. The aims of the present study were (1) to evaluate the difference between top-ranked and club sailors, in their capacity to resist fatigue during sustained isometric and maximal power exercise, and (2) to examine the relationships between the above parameters and performance on a Laser simulator and competitive racing performance according to the national ranking list. Eight Greek nationally ranked Laser sailors were compared with eight club sailors. Each sailor performed: (a) an effort to the limit of tolerance on the Laser simulator, (b) an effort to the limit of tolerance of isometric endurance for the right leg on an isokinetic dynamometer, and (c) a Wingate test of maximal lower-body anaerobic power on a cycle ergometer. In the nationally ranked sailors, isometric endurance time (mean 160 s, s = 50) and endurance time on the Laser simulator (1381 s, s = 1354) were significantly (P < 0.05) longer than in the club sailors (101 s, s = 29 and 565 s, s = 367, respectively), whereas the final minute heart rate (in both groups: 149 beats . min(-1), s = 22) and the mean arterial pressure (nationally ranked sailors: 129 mmHg, s = 16; club sailors: 120 mmHg, s = 21) on the Laser simulator were not different between groups. During the Wingate test, the nationally ranked sailors had a significantly lower index of fatigue (42%, s = 5) than the club sailors (49%, s = 6). Isometric endurance time was significantly correlated with the Wingate index of fatigue (r = -0.73; P < 0.001). The nationally ranked sailors' mean and maximal anaerobic powers were significantly correlated with their national ranking positions (r = -0.83 and -0.71, respectively). It is suggested that isometric endurance and anaerobic power are well-developed in Laser class sailors and may influence their sailing performance. Furthermore, compared with club sailors, the nationally ranked sailors are able
Liu, W-T; Wang, C-H; Lin, H-C; Lin, S-M; Lee, K-Y; Lo, Y-L; Hung, S-H; Chang, Y-M; Chung, K F; Kuo, H-P
The application of a supervised endurance exercise training programme in a home setting offering convenience and prolonged effects is a challenge. In total, 48 patients were initially assessed by the incremental shuttle walk test (ISWT), spirometry and the Short Form-12 (SF-12) quality-of-life questionnaire, and then every 4 weeks for 3 months thereafter and again after 1 yr. During the first 3 months, 24 patients in the cell phone group were asked to perform daily endurance walking at 80% of their maximal capacity by following the tempo of music from a program installed on a cell phone. The level of endurance walking at home was readjusted monthly according to the result of ISWT. In the control group, 24 patients received the same protocol and were verbally asked to take daily walking exercise at home. Patients in the cell phone group significantly improved their ISWT distance and duration of endurance walking after 8 weeks. The improvements in ISWT distance, inspiratory capacity and SF-12 scoring at 12 weeks persisted until the end of the study, with less acute exacerbations and hospitalisations. In the present pilot study, the cell phone-based system provides an efficient, home endurance exercise training programme with good compliance and clinical outcomes in patients with moderate-to-severe chronic obstructive pulmonary disease.
Andersen, Grete; Ørngreen, Mette C; Preisler, Nicolai; Jeppesen, Tina D; Krag, Thomas O; Hauerslev, Simon; van Hall, Gerrit; Vissing, John
In healthy individuals, postexercise protein supplementation increases muscle protein anabolism. In patients with muscular dystrophies, aerobic exercise improves muscle function, but the effect of exercise on muscle protein balance is unknown. Therefore, we investigated 1) muscle protein balance before, during, and after exercise and 2) the effect of postexercise protein-carbohydrate supplementation on muscle protein balance in patients with muscular dystrophies. In 17 patients [7 women and 10 men, aged 33 ± 11 yr (18-52), body mass index: 22 ± 3 kg/m(2) (16-26)] and 8 healthy matched controls [3 women and 5 men, age 33 ± 13 years (19-54), body mass index: 23 ± 3 kg/m(2) (19-27)], muscle protein synthesis, breakdown, and fractional synthesis rates (FSR) were measured across the leg using tracer dilution methodology on two occasions, with and without oral postexercise protein-carbohydrate supplementation. In patients, muscle protein breakdown increased in the recovery period (11 ± 1 μmol phenylalanine/min) vs. rest (8 ± 1 μmol phenylalanine/min, P = 0.02), enhancing net muscle protein loss. In contrast, postexercise protein-carbohydrate supplementation reduced protein breakdown, abolished net muscle protein loss, and increased the muscle FSR in patients (0.04 to 0.06%/h; P = 0.03). In conclusion, postexercise protein-carbohydrate supplementation reduces skeletal mixed-muscle protein breakdown, enhances FSR, resulting in a reduced net muscle loss in patients with muscular dystrophies. The findings suggest that postexercise protein-carbohydrate supplementation could be an important add-on to exercise training therapy in muscular dystrophies, and long-term studies of postexercise protein-carbohydrate supplementation are warranted in these conditions.
Vikmoen, Olav; Rønnestad, Bent R; Ellefsen, Stian; Raastad, Truls
The purpose of this study was to investigate the effects of adding heavy strength training to female duathletes' normal endurance training on both cycling and running performance. Nineteen well-trained female duathletes (VO2max cycling: 54 ± 3 ml∙kg(-1)∙min(-1), VO2max running: 53 ± 3 ml∙kg(-1)∙min(-1)) were randomly assigned to either normal endurance training (E, n = 8) or normal endurance training combined with strength training (E+S, n = 11). The strength training consisted of four lower body exercises [3 × 4-10 repetition maximum (RM)] twice a week for 11 weeks. Running and cycling performance were assessed using 5-min all-out tests, performed immediately after prolonged periods of submaximal work (3 h cycling or 1.5 h running). E+S increased 1RM in half squat (45 ± 22%) and lean mass in the legs (3.1 ± 4.0%) more than E Performance during the 5-min all-out test increased in both cycling (7.0 ± 4.5%) and running (4.7 ± 6.0%) in E+S, whereas no changes occurred in E The changes in running performance were different between groups. E+S reduced oxygen consumption and heart rate during the final 2 h of prolonged cycling, whereas no changes occurred in E No changes occurred during the prolonged running in any group. Adding strength training to normal endurance training in well-trained female duathletes improved both running and cycling performance when tested immediately after prolonged submaximal work.
van Loon, Luc J C
Dietary protein ingestion after exercise stimulates muscle protein synthesis, inhibits protein breakdown and, as such, stimulates net muscle protein accretion following resistance as well as endurance type exercise. Protein ingestion during and/or immediately after exercise has been suggested to facilitate the skeletal muscle adaptive response to each exercise session, resulting in more effective muscle reconditioning. A few basic guidelines can be defined with regard to the preferred type and amount of dietary protein and the timing by which protein should be ingested. Whey protein seems to be most effective to increase post-exercise muscle protein synthesis rates. This is likely attributed to its rapid digestion and absorption kinetics and specific amino acid composition. Ingestion of approximately 20 g protein during and/or immediately after exercise is sufficient to maximize post-exercise muscle protein synthesis rates. Additional ingestion of large amounts of carbohydrate does not further increase post-exercise muscle protein synthesis rates when ample protein is already ingested. Dietary protein should be ingested during and/or immediately after cessation of exercise to allow muscle protein synthesis rates to reach maximal levels. Future research should focus on the impact of the timing of protein provision throughout the day on the adaptive response to more prolonged exercise training.
Ferguson-Stegall, Lisa; McCleave, Erin L; Ding, Zhenping; Kammer, Lynne M; Wang, Bei; Doerner, Phillip G; Liu, Yang; Ivy, John L
Ingesting carbohydrate plus protein during prolonged variable intensity exercise has demonstrated improved aerobic endurance performance beyond that of a carbohydrate supplement alone. The purpose of the present study was to determine if a supplement containing a mixture of different carbohydrates (glucose, maltodextrin, and fructose) and a moderate amount of protein given during endurance exercise would increase time to exhaustion (TTE), despite containing 50% less total carbohydrate than a carbohydrate-only supplement. We also sought post priori to determine if there was a difference in effect based on percentage of ventilatory threshold (VT) at which the subjects cycled to exhaustion. Fifteen trained male and female cyclists exercised on 2 separate occasions at intensities alternating between 45 and 70% VO2max for 3 hours, after which the workload increased to ∼74-85% VO2max until exhaustion. Supplements (275 mL) were provided every 20 minutes during exercise, and these consisted of a 3% carbohydrate/1.2% protein supplement (MCP) and a 6% carbohydrate supplement (CHO). For the combined group (n = 15), TTE in MCP did not differ from CHO (31.06 ± 5.76 vs. 26.03 ± 4.27 minutes, respectively, p = 0.064). However, for subjects cycling at or below VT (n = 8), TTE in MCP was significantly greater than for CHO (45.64 ± 7.38 vs. 35.47 ± 5.94 minutes, respectively, p = 0.006). There were no significant differences in TTE for the above VT group (n = 7). Our results suggest that, compared to a traditional 6% CHO supplement, a mixture of carbohydrates plus a moderate amount of protein can improve aerobic endurance at exercise intensities near the VT, despite containing lower total carbohydrate and caloric content.
Skirka, Nicholas; Hume, Donald
This article discusses how to use stretch bands for improving total body fitness and quality of life. A stretch band exercise program offers a versatile and inexpensive option to motivate participants to exercise. The authors suggest practical exercises that can be used in physical education to improve or maintain muscular strength and endurance,…
Flethøj, Mette; Kanters, Jørgen K; Haugaard, Maria M; Pedersen, Philip J; Carstensen, Helena; Balling, Johanne D; Olsen, Lisbeth H; Buhl, Rikke
OBJECTIVE To evaluate heart rate, heart rate variability, and arrhythmia frequency as well as changes in cardiac biomarker values and their association with heart rate in horses before and after an endurance ride. DESIGN Cross-sectional study. ANIMALS 28 Arabian horses competing in a 120- or 160-km endurance ride. PROCEDURES ECG recordings were obtained from each horse before (preride) and after (recovery) an endurance ride to evaluate changes in heart rate and the SD of normal R-R intervals (SDNN) during the initial 12 hours of recovery. Frequencies of supraventricular and ventricular premature complexes before and after the ride were evaluated. Blood samples were obtained before the ride and twice during recovery. Hematologic analyses included measurement of serum cardiac troponin I concentration and creatine kinase isoenzyme MB activity. RESULTS Heart rate was significantly increased and SDNN was decreased during the recovery versus preride period. Frequency of ventricular premature complexes increased during recovery, albeit not significantly, whereas frequency of supraventricular premature complexes was not significantly different between preride and recovery periods. Serum cardiac troponin I concentration and creatine kinase isoenzyme MB activity were significantly increased in the recovery versus preride period. No associations were identified between cardiac biomarkers and velocity, distance, or mean heart rate. CONCLUSIONS AND CLINICAL RELEVANCE Heart rate increased and SDNN decreased in horses after completion of an endurance ride. These and other cardiac changes suggested that prolonged exercise such as endurance riding might have cardiac effects in horses. Additional studies are needed to clarify the clinical relevance of the findings.
Che Muhamed, Ahmad Munir; Atkins, Kerry; Stannard, Stephen R.; Mündel, Toby; Thompson, Martin William
ABSTRACT This study examined the thermoregulatory and circulatory responses, and exercise performance of trained distance runners during exercise in the heat (31°C) at varying relative humidity (RH). In a randomized order, 11 trained male distance runners performed 5 60 min steady-state runs at a speed eliciting 70% of VO2max in RH of 23, 43, 52, 61 and 71%. This was followed immediately with an incremental exercise test to volitional exhaustion. Core (Tre) and mean skin temperature (T¯sk), cardiac output (Q), heart rate (HR), and stroke volume (SV) were recorded at regular intervals. A significant (P = 0.003) main effect was detected for RH on mean body temperature (Tb), with a significantly higher Tb detected during steady-state exercise in the 61 and 71% RH compared to that in the 23% RH. During the steady-state exercise, no differences were detected in whole body sweat loss (P = 0.183). However, a significant main effect of RH was observed for HR and SV (P = 0.001 and 0.006, respectively) but not Q (P = 0.156). The time to exhaustion of the incremental exercise test was significantly reduced at 61 and 71% RH compared with 23% RH (P = 0.045 and 0.005, respectively). Despite an increase in dry heat loss, a greater thermoregulatory and circulatory stress was evident during steady-state exercise at 61 and 71% RH. This ultimately limits the capacity to perform the subsequent incremental exercise to exhaustion. This study highlighted that in a warm environment, the range of the prescriptive zone progressively narrows as RH increases. PMID:28349085
Marchant, David C.; Greig, Matt; Bullough, Jonathan; Hitchen, Daniel
The influence of internal (movement focus) and external (outcome focus) attentional-focusing instructions on muscular endurance were investigated using three exercise protocols with experienced exercisers. Twenty-three participants completed a maximal repetition, assisted bench-press test on a Smith's machine. An external focus of attention…
There have been significant changes in the understanding of the role of carbohydrates during endurance exercise in recent years, which allows for more specific and more personalized advice with regard to carbohydrate ingestion during exercise. The new proposed guidelines take into account the duration (and intensity) of exercise and advice is not restricted to the amount of carbohydrate; it also gives direction with respect to the type of carbohydrate. Studies have shown that during exercise lasting approximately 1 h in duration, a mouth rinse or small amounts of carbohydrate can result in a performance benefit. A single carbohydrate source can be oxidized at rates up to approximately 60 g/h and this is the recommendation for exercise that is more prolonged (2-3 h). For ultra-endurance events, the recommendation is higher at approximately 90 g/h. Carbohydrate ingested at such high ingestion rates must be a multiple transportable carbohydrates to allow high oxidation rates and prevent the accumulation of carbohydrate in the intestine. The source of the carbohydrate may be a liquid, semisolid, or solid, and the recommendations may need to be adjusted downward when the absolute exercise intensity is low and thus carbohydrate oxidation rates are also low. Carbohydrate intake advice is independent of body weight as well as training status. Therefore, although these guidelines apply to most athletes, they are highly dependent on the type and duration of activity. These new guidelines may replace the generic existing guidelines for carbohydrate intake during endurance exercise.
Seidl, Jamie; Asplund, Chad A
Regular moderate exercise confers many cardiovascular and health benefits. Because of this, endurance sports events have become very popular with participation increasing tremendously over the past few years. In conjunction with this increase in popularity and participation, people also have increased the amount that they exercise with many training for and competing in ultraendurance events such as ultradistance running events, iron distance triathlons, or multiday races. This excess endurance activity may appear to increase the risk of cardiac abnormalities, which may increase the risk for long-term morbidity or mortality. While it is known that moderate exercise has benefits to cardiovascular health, ultimately, the long-term cardiac effects of excessive endurance activity are unclear. What is clear, however, is that moderate exercise is beneficial, and to date, the evidence does not support recommending against physical activity.
Przyborowski, Kamil; Wojewoda, Marta; Sitek, Barbara; Zakrzewska, Agnieszka; Kij, Agnieszka; Wandzel, Krystyna; Zoladz, Jerzy Andrzej; Chlopicki, Stefan
1-Methylnicotinamide (MNA), which was initially considered to be a biologically inactive endogenous metabolite of nicotinamide, has emerged as an anti-thrombotic and anti-inflammatory agent with the capacity to release prostacyclin (PGI2). In the present study, we characterized the effects of MNA on exercise capacity and the endothelial response to exercise in diabetic mice. Eight-week-old db/db mice were untreated or treated with MNA for 4 weeks (100 mg·kg-1), and their exercise capacity as well as NO- and PGI2-dependent response to endurance running were subsequently assessed. MNA treatment of db/db mice resulted in four-fold and three-fold elevation of urine concentrations of MNA and its metabolites (Met-2PY + Met-4PY), respectively (P<0.01), but did not affect HbA1c concentration, fasting glucose concentration or lipid profile. However, insulin sensitivity was improved (P<0.01). In MNA-treated db/db mice, the time to fatigue for endurance exercise was significantly prolonged (P<0.05). Post-exercise Δ6-keto-PGF1α (difference between mean concentration in the sedentary and exercised groups) tended to increase, and post-exercise leukocytosis was substantially reduced in MNA-treated animals. In turn, the post-exercise fall in plasma concentration of nitrate was not affected by MNA. In conclusion, we demonstrated for the first time that MNA improves endurance exercise capacity in mice with diabetes, and may also decrease the cardiovascular risk of exercise. PMID:26115505
Jeukendrup, Asker E
Endurance sports are increasing in popularity and athletes at all levels are looking for ways to optimize their performance by training and nutrition. For endurance exercise lasting 30 min or more, the most likely contributors to fatigue are dehydration and carbohydrate depletion, whereas gastrointestinal problems, hyperthermia, and hyponatraemia can reduce endurance exercise performance and are potentially health threatening, especially in longer events (>4 h). Although high muscle glycogen concentrations at the start may be beneficial for endurance exercise, this does not necessarily have to be achieved by the traditional supercompensation protocol. An individualized nutritional strategy can be developed that aims to deliver carbohydrate to the working muscle at a rate that is dependent on the absolute exercise intensity as well as the duration of the event. Endurance athletes should attempt to minimize dehydration and limit body mass losses through sweating to 2-3% of body mass. Gastrointestinal problems occur frequently, especially in long-distance races. Problems seem to be highly individual and perhaps genetically determined but may also be related to the intake of highly concentrated carbohydrate solutions, hyperosmotic drinks, as well as the intake of fibre, fat, and protein. Hyponatraemia has occasionally been reported, especially among slower competitors with very high intakes of water or other low sodium drinks. Here I provide a comprehensive overview of recent research findings and suggest several new guidelines for the endurance athlete on the basis of this. These guidelines are more detailed and allow a more individualized approach.
Brenmoehl, J; Ohde, D; Albrecht, E; Walz, C; Tuchscherer, A; Hoeflich, A
For the assessment of genetic or conditional factors of fat cell browning, novel and polygenic animal models are required. Therefore, the long-term selected polygenic mouse line DUhTP originally established in Dummerstorf for high treadmill performance is used. DUhTP mice are characterized by increased fat accumulation in the sedentary condition and elevated fat mobilization during mild voluntary physical activity. In the present study, the phenotype of fat cell browning of subcutaneous fat and a potential effect on oral glucose tolerance, an indicator of metabolic health, were addressed in DUhTP mice. Analysis of peripheral fat pads revealed increased brite (brown-in-white) subcutaneous adipose tissues and in subcutaneous fat from DUhTP mice higher levels of irisin and different markers of fat cell browning like T-box transcription factor (Tbx1), PPARα, and uncoupling protein (UCP1) (P < 0.05) when compared to unselected controls. UCP1 was further increased in subcutaneous fat from DUhTP mice in response to mild exercise (fourfold, P < 0.05). In addition, surface temperature of DUhTP mice was increased when compared to controls indicating a physiological effect of increased UCP1 expression. The present study suggests that DUhTP mice exhibit different markers of mitochondrial biogenesis and fat browning without external stimuli. At an age of 43 days, sedentary DUhTP mice have improved metabolic health as judged from lower levels of blood glucose after an oral glucose tolerance test. Consequently, the non-inbred mouse model DUhTP represents a novel model for the identification of fat cell browning mechanisms in white adipose tissues.
Lee, Stuart; Hargens, A. R.; Schneider, S. M.; Watenpaugh, D. E.
An integrated exercise countermeasure for microgravity is needed to protect multiple physiologic systems and save crew time. Such a countermeasure should protect orthostatic tolerance, upright ambulatory capability (including sprinting), aerobic capacity, muscle strength/endurance, and other physiologic parameters relevant to human performance. We developed a novel physiologic countermeasure, treadmill exercise within LBNP, for preventing cardiovascular and musculoskeletal deconditioning associated with prolonged bed rest and spaceflight. We evaluated 40 min of daily LBNP treadmill exercise by a battery of physiologic parameters relevant to maintaining exercise performance and health of both women and men during bed-rest (simulated microgravity) studies lasting from 5 to 60 days. For 30 day studies, we employed identical twins with one twin as the control and the other twin as the exerciser to improve comparative power. During the WISE 60-day HDT study, the treadmill exercise within LBNP was performed 3-4 days each week and resistive exercise was performed 2-3 days each week. Our treadmill within LBNP protocol maintained plasma volume and sprint speed (30 day HDT bed-rest studies of identical twins), orthostatic tolerance to a degree, upright exercise capacity, muscle strength and endurance, and some bone parameters during 30 day (twin studies) and 60 day (WISE-2005) bed-rest simulations of microgravity. When combining treadmill exercise within LBNP and resistive exercise (WISE), cardiac mass increased significantly in the exercise (EX) group during bed rest relative to controls (CON). Upright peak VO2, and knee extensor strength and endurance decreased significantly in CON subjects; but these parameters were preserved in the EX group. In the 60 day WISE study, each LBNP exercise session was followed immediately by 10 minutes of static LBNP, and the last such session occurred three days before the end of bed rest. Still, orthostatic tolerance was better maintained
Nordsborg, Nikolai B; Calbet, José A L; Sander, Mikael; van Hall, Gerrit; Juel, Carsten; Saltin, Bengt; Lundby, Carsten
It was investigated whether skeletal muscle K(+) release is linked to the degree of anaerobic energy production. Six subjects performed an incremental bicycle exercise test in normoxic and hypoxic conditions prior to and after 2 and 8 wk of acclimatization to 4,100 m. The highest workload completed by all subjects in all trials was 260 W. With acute hypoxic exposure prior to acclimatization, venous plasma [K(+)] was lower (P < 0.05) in normoxia (4.9 +/- 0.1 mM) than hypoxia (5.2 +/- 0.2 mM) at 260 W, but similar at exhaustion, which occurred at 400 +/- 9 W and 307 +/- 7 W (P < 0.05), respectively. At the same absolute exercise intensity, leg net K(+) release was unaffected by hypoxic exposure independent of acclimatization. After 8 wk of acclimatization, no difference existed in venous plasma [K(+)] between the normoxic and hypoxic trial, either at submaximal intensities or at exhaustion (360 +/- 14 W vs. 313 +/- 8 W; P < 0.05). At the same absolute exercise intensity, leg net K(+) release was less (P < 0.001) than prior to acclimatization and reached negative values in both hypoxic and normoxic conditions after acclimatization. Moreover, the reduction in plasma volume during exercise relative to rest was less (P < 0.01) in normoxic than hypoxic conditions, irrespective of the degree of acclimatization (at 260 W prior to acclimatization: -4.9 +/- 0.8% in normoxia and -10.0 +/- 0.4% in hypoxia). It is concluded that leg net K(+) release is unrelated to anaerobic energy production and that acclimatization reduces leg net K(+) release during exercise.
Wilson, Patrick B
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.
Kloubec, June A
Many claims have been made about the effectiveness of Pilates exercise on the basic parameters of fitness. The purpose of this study was to determine the effects of Pilates exercise on abdominal endurance, hamstring flexibility, upper-body muscular endurance, posture, and balance. Fifty subjects were recruited to participate in a 12-week Pilates class, which met for 1 hour 2 times per week. Subjects were randomly assigned to either the experimental (n = 25) or control group (n = 25). Subjects performed the essential (basic) mat routine consisting of approximately 25 separate exercises focusing on muscular endurance and flexibility of the abdomen, low back, and hips each class session. At the end of the 12-week period, a 1-way analysis of covariance showed a significant level of improvement (p < or = 0.05) in all variables except posture and balance. This study demonstrated that in active middle-aged men and women, exposure to Pilates exercise for 12 weeks, for two 60-minute sessions per week, was enough to promote statistically significant increases in abdominal endurance, hamstring flexibility, and upper-body muscular endurance. Participants did not demonstrate improvements in either posture or balance when compared with the control group. Exercise-training programs that address physical inactivity concerns and that are accessible and enjoyable to the general public are a desirable commodity for exercise and fitness trainers. This study suggests that individuals can improve their muscular endurance and flexibility using relatively low-intensity Pilates exercises that do not require equipment or a high degree of skill and are easy to master and use within a personal fitness routine.
Tang, Xuan; Zhuang, Jingjing; Chen, Jing; Yu, Liang; Hu, Lihong; Jiang, Hualiang; Shen, Xu
Physical inactivity is considered as one of the potential risk factors for the development of type 2 diabetes and other metabolic diseases, while endurance exercise training could enhance fat oxidation that is associated with insulin sensitivity improvement in obesity. AMP-activated protein kinase (AMPK) as an energy sensor plays pivotal roles in the regulation of energy homeostasis, and its activation could improve glucose uptake, promote mitochondrial biogenesis and increase glycolysis. Recent research has even suggested that AMPK activation contributed to endurance enhancement without exercise. Here we report that the natural product arctigenin from the traditional herb Arctium lappa L. (Compositae) strongly increased AMPK phosphorylation and subsequently up-regulated its downstream pathway in both H9C2 and C2C12 cells. It was discovered that arctigenin phosphorylated AMPK via calmodulin-dependent protein kinase kinase (CaMKK) and serine/threonine kinase 11(LKB1)-dependent pathways. Mice treadmill based in vivo assay further indicated that administration of arctigenin improved efficiently mice endurance as reflected by the increased fatigue time and distance, and potently enhanced mitochondrial biogenesis and fatty acid oxidation (FAO) related genes expression in muscle tissues. Our results thus suggested that arctigenin might be used as a potential lead compound for the discovery of the agents with mimic exercise training effects to treat metabolic diseases.
O'Leary, Thomas J; Collett, Johnny; Howells, Ken; Morris, Martyn G
High-intensity exercise induces significant central and peripheral fatigue, however the effect of endurance training on these mechanisms of fatigue is poorly understood. We compared the effect of cycling endurance training of disparate intensities on high-intensity exercise endurance capacity and the associated limiting central and peripheral fatigue mechanisms. Twenty adults were randomly assigned to 6 weeks of either high-intensity interval training (HIIT, 6-8 × 5 min at halfway between lactate threshold and maximal oxygen uptake [50%Δ]) or volume matched moderate-intensity continuous training (CONT, ~60-80 min at 90% lactate threshold). Two time to exhaustion (TTE) trials at 50%Δ were completed pre- and post-training to assess endurance capacity; the two post-training trials were completed at the pre-training 50%Δ (same absolute intensity) and the 'new' post-training 50%Δ (same relative intensity). Pre- and post-exercise responses to femoral nerve and motor cortex stimulation were examined to determine peripheral and central fatigue, respectively. HIIT resulted in greater increases in TTE at the same absolute and relative intensities as pre-training (148% and 43%, respectively) compared with CONT (38% and -4%, respectively). Compared with pre-training, HIIT increased the level of potentiated quadriceps twitch reduction (-34% vs -43%, respectively) and attenuated the level of voluntary activation reduction (-7% vs -3%, respectively) following the TTE trial at the same relative intensity. There were no other training effects on neuromuscular fatigue development. This suggests that central fatigue resistance contributes to enhanced high-intensity exercise endurance capacity after HIIT by allowing greater performance to be extruded from the muscle. This article is protected by copyright. All rights reserved.
Lepers, Romuald; Stapley, Paul J.
The increased participation of master athletes (i.e., >40 years old) in endurance and ultra-endurance events (>6 h duration) over the past few decades has been accompanied by an improvement in their performances at a much faster rate than their younger counterparts. Aging does however result in a decrease in overall endurance performance. Such age-related declines in performance depend upon the modes of locomotion, event duration, and gender of the participant. For example, smaller age-related declines in cycling performance than in running and swimming have been documented. The relative stability of gender differences observed across the ages suggests that the age-related declines in physiological function did not differ between males and females. Among the main physiological determinants of endurance performance, the maximal oxygen consumption (VO2max) appears to be the parameter that is most altered by age. Exercise economy and the exercise intensity at which a high fraction of VO2max can be sustained (i.e., lactate threshold), seem to decline to a lesser extent with advancing age. The ability to maintain a high exercise-training stimulus with advancing age is emerging as the single most important means of limiting the rate of decline in endurance performance. By constantly extending the limits of (ultra)-endurance, master athletes therefore represent an important insight into the ability of humans to maintain physical performance and physiological function with advancing age. PMID:28018241
Convertino, Victor A.
Expansion of blood volume (hypervolemia) has been well documented in both cross-sectional and longitudinal studies as a consequence of endurance exercise training. Plasma volume expansion can account for nearly all of the exercise-induced hypervolemia up to 2-4 wk; after this time expansion may be distributed equally between plasma and red cell volumes. The exercise stimulus for hypervolemia has both thermal and nonthermal components that increase total circulating plasma levels of electrolytes and proteins. Although protein and fluid shifts from the extravascular to intravascular space may provide a mechanism for rapid hypervolemia immediately after exercise, evidence supports the notion that chronic hypervolemia associated with exercise training represents a net expansion of total body water and solutes. This net increase of body fluids with exercise training is associated with increased water intake and decreased urine volume output. The mechanism of reduced urine output appears to be increased renal tubular reabsorption of sodium through a more sensitive aldosterone action in man. Exercise training-induced hypervolemia appears to be universal among most animal species, although the mechanisms may be quite different. The hypervolemia may provide advantages of greater body fluid for heat dissipation and thermoregulatory stability as well as larger vascular volume and filling pressure for greater cardiac stroke volume and lower heart rates during exercise.
Galloway, Stuart D R; Talanian, Jason L; Shoveller, Anna K; Heigenhauser, George J F; Spriet, Lawrence L
This study examined 1) the plasma taurine response to acute oral taurine supplementation (T), and 2) the effects of 7 days of T on muscle amino acid content and substrate metabolism during 2 h of cycling at approximately 60% peak oxygen consumption (VO2peak). In the first part of the study, after an overnight fast, 7 volunteers (28+/-3 yr, 184+/-2 cm, 88.0+/-6.6 kg) ingested 1.66 g oral taurine doses with breakfast (8 AM) and lunch (12 noon), and blood samples were taken throughout the day. In the second part of the study, eight men (22+/-1 yr, 181+/-1 cm, 80.9+/-3.8 kg, 4.21+/-0.16 l/min VO2peak) cycled for 2 h after 7 days of placebo (P) ingestion (6 g glucose/day) and again following 7 days of T (5 g/day). In the first part of the study, plasma taurine was 64+/-4 microM before T and rose rapidly to 778+/-139 microM by 10 AM and remained elevated at noon (359+/-56 microM). Plasma taurine reached 973+/-181 microM at 1 PM and was 161+/-31 microM at 4 PM. In the second part of the study, seven days of T had no effect on muscle taurine content (mmol/kg dry muscle) at rest (P, 44+/-15 vs. T, 42+/-15) or after exercise (P, 43+/-12 vs. T, 43+/-11). There was no difference in muscle glycogen or other muscle metabolites between conditions, but there were notable interaction effects for muscle valine, isoleucine, leucine, cystine, glutamate, alanine, and arginine amino acid content following exercise after T. These data indicate that 1) acute T produces a 13-fold increase in plasma taurine concentration; 2) despite the ability to significantly elevate plasma taurine for extended periods throughout the day, 7 days of T does not alter skeletal muscle taurine content or carbohydrate and fat oxidation during exercise; and 3) T appears to have some impact on muscle amino acid response to exercise.
Malin, Steven K; Cotugna, Nancy
Minimal evidence has shown creatine (Cr) supplementation to enhance endurance performance in either humans or rats. The purpose of this study was to examine the effects of Cr supplementation on endurance performance during high-intensity exercise in trained male rats. Endurance performance was defined as the distance run. Sixteen days of running were performed over 28 days. A cycle of 7 days consisted of 2 days of training, 1 day off, 2 days of training then 2 days off and this was repeated over a total of 28 days. Cr was administered on all 28 days. Treatment rats (n = 7) drank water containing Cr while the control rats drank water with no supplement (n = 6). The Cr group's average distance run increased significantly from baseline to exercise day 16 (baseline = 128.91 m ± 18.23 vs. exercise day 16 = 217.11m ± 18.11; p < 0.005), while the control groups did not (baseline = 137.24 m ± 10.14, exercise day 16 = 101.04 m ± 14.97; p > 0.05). Over the course of the study, the treatment group's running endurance improved by 81% compared to baseline (p < 0.001) and we conclude that Cr supplementation provided rats an increased ability to run farther demonstrating possible implications for improving endurance athletes' performances.
Zhang, Haifeng; Tong, Tom K.; Qiu, Weifeng; Zhang, Xu; Zhou, Shi
This study compared the effect of prolonged moderate-intensity continuous training (MICT) on reducing abdominal visceral fat in obese young women with that of work-equivalent (300 kJ/training session) high-intensity interval training (HIIT). Forty-three participants received either HIIT (n = 15), MICT (n = 15), or no training (CON, n = 13) for 12 weeks. The abdominal visceral fat area (AVFA) and abdominal subcutaneous fat area (ASFA) of the participants were measured through computed tomography scans preintervention and postintervention. Total fat mass and the fat mass of the android, gynoid, and trunk regions were assessed through dual-energy X-ray absorptiometry. Following HIIT and MICT, comparable reductions in AVFA (−9.1, −9.2 cm2), ASFA (−35, −28.3 cm2), and combined AVFA and ASFA (−44.7, −37.5 cm2, p > 0.05) were observed. Similarly, reductions in fat percentage (−2.5%, −2.4%), total fat mass (−2.8, −2.8 kg), and fat mass of the android (−0.3, −0.3 kg), gynoid (−0.5, −0.7 kg), and trunk (−1.6, −1.2 kg, p > 0.05) regions did not differ between HIIT and MICT. No variable changed in CON. In conclusion, MICT consisting of prolonged sessions has no quantitative advantage, compared with that resulting from HIIT, in abdominal visceral fat reduction. HIIT appears to be the predominant strategy for controlling obesity because of its time efficiency. PMID:28116314
Greenleaf, J. E.; Hargens, Alan R. (Technical Monitor)
A 30-day 6 deg. head-down bed rest study was conducted to evaluate high-intensity, short-duration, alternating isotonic cycle ergometer exercise (ITE) training and high-intensity intermittent isokinetic exercise (IKE) training regiments designed to maintain peak VO2 and muscle mass, strength, and endurance at ambulatory control levels throughout prolonged bed rest. Other elements of the deconditioning (acclimation) syndrome, such as proprioception, psychological performance, hypovolemia, water balance, body composition, and orthostatic tolerance, were also measured. Compared with response during bed rest of the no exercise (NOE) control group: the ITE training regimen (a) maintained work capacity (peak VO2), (b) maintained plasma and red cell volume, (c) induced positive body water balance, (d) decreased quality of sleep and mental concentration, and (e) had no effect on the decrease in orthostatic tolerance; the IKE training regimen (a) attenuated the decrease in peak VO2 by 50%, (b) attenuated loss of red cell volume by 40%, but had no effect on loss of plasma volume, (c) induced positive body water balance, (d) had no adverse effect on quality of sleep or concentration, and (e) had no effect on the decrease in orthostatic tolerance. These findings suggest that various elements of the deconditioning syndrome can be manipulated by duration and intensity of ITE or IKE training regiments, and that several different training protocols will be required to maintain or restore physiological and psychological performance of individuals confined to prolonged bed rest.
Shan, Xiaozhong; Zhou, Junlai; Ma, Tao; Chai, Qiongxia
The purpose of the present study was to investigate the effects of Lycium barbarum polysaccharides (LBP) on exercise-induced oxidative stress in rats. Rats were divided into four groups, i.e., one control group and three LBP treated groups. The animals received an oral administration of physiological saline or LBP (100, 200 and 400 mg/kg body weight) for 28 days. On the day of the exercise test, rats were required to run to exhaustion on the treadmill. Body weight, endurance time, malondialdehyde (MDA), super oxide dismutase (SOD) and glutathione peroxidase (GPX) level of rats were measured. The results showed that the body weight of rats in LBP treated groups were not significantly different from that in the normal control group before and after the experiment (P > 0.05). After exhaustive exercise, the mean endurance time of treadmill running to exhaustion of rats in LBP treated groups were significantly prolonged compared with that in the normal control group. MDA levels of rats in LBP treated groups were significantly decreased compared with that in the normal control group (P < 0.05). SOD and GPX levels of rats in LBP treated groups were significantly increased compared with that in the normal control group (P < 0.05). Together, these results indicate that LBP was effective in preventing oxidative stress after exhaustive exercise. PMID:21541044
Karamanolis, I A; Laparidis, K S; Volaklis, K A; Douda, H T; Tokmakidis, S P
This study examined the effects of pre-exercise food on different glycemic indexes (GI) on exercise metabolism and endurance running capacity. 9 subjects performed 3 exercise trials on different days 15 min after ingesting: lentils, (LGI), potatoes, (HGI), and placebo. Each subject ingested an equal amount of each food (1 g/kg body mass) and ran on a level treadmill for 5 min at 60%, 45 min at 70% and then at 80% of VO (2max) until exhaustion. Serum glucose concentrations were higher ( P<0.01) 15 min after the HGI trial compared to the LGI and placebo trials. In addition, serum glucose levels were higher ( P<0.05) during the LGI trial at the time of exhaustion compared to the HGI and placebo trials. Plasma insulin levels, 15 min after ingestion, were higher ( P<0.001) in the HGI trial as compared to the LGI and placebo trials. Exercise time was longer during the LGI trial ( P<0.05) compared to the placebo, but the time to exhaustion in the HGI condition did not differ from the placebo (LGI: 90.0 ± 7.9; HGI: 81.8 ± 5; placebo: 73.0 ± 6.4 min). These results suggest that lentils, the LGI food, ingested 15 min before prolonged exercise maintained euglycemia during exercise and enhanced endurance running capacity.
Falavigna, Gina; Junior, Jonas Alves de Araújo; Rogero, Marcelo Macedo; Pires, Ivanir Santana de Oliveira; Pedrosa, Rogério Graça; Junior, Eivor Martins; de Castro, Inar Alves; Tirapegui, Julio
This study aimed to determine the effects of diets chronically supplemented with branched-chain amino acids (BCAA) on the fatigue mechanisms of trained rats. Thirty-six adult Wistar rats were trained for six weeks. The training protocol consisted of bouts of swimming exercise (one hour a day, five times a week, for six weeks). The animals received a control diet (C) (n = 12), a diet supplemented with 3.57% BCAA (S1) (n = 12), or a diet supplemented with 4.76% BCAA (S2) (n = 12). On the last day of the training protocol, half the animals in each group were sacrificed after one hour of swimming (1H), and the other half after a swimming exhaustion test (EX). Swimming time until exhaustion was increased by 37% in group S1 and reduced by 43% in group S2 compared to group C. Results indicate that the S1 diet had a beneficial effect on performance by sparing glycogen in the soleus muscle (p < 0.05) and by inducing a lower concentration of plasma ammonia, whereas the S2 diet had a negative effect on performance due to hyperammonemia (p < 0.05). The hypothalamic concentration of serotonin was not significantly different between the 1H and EX conditions. In conclusion, chronic BCAA supplementation led to increased performance in rats subjected to a swimming test to exhaustion. However, this is a dose-dependent effect, since chronic ingestion of elevated quantities of BCAA led to a reduction in performance. PMID:23201847
Gruttad’Auria, Claudia I.; Baiamonte, Pierpaolo; Mazzuca, Emilia; Castrogiovanni, Alessandra; Bonsignore, Maria R.
Educational aims To illustrate the characteristics of endurance exercise training and its positive effects on health. To provide an overview on the effects of endurance training on airway cells and bronchial reactivity. To summarise the current knowledge on respiratory health problems in elite athletes. Endurance exercise training exerts many positive effects on health, including improved metabolism, reduction of cardiovascular risk, and reduced all-cause and cardiovascular mortality. Intense endurance exercise causes mild epithelial injury and inflammation in the airways, but does not appear to exert detrimental effects on respiratory health or bronchial reactivity in recreational/non-elite athletes. Conversely, elite athletes of both summer and winter sports show increased susceptibility to development of asthma, possibly related to environmental exposures to allergens or poor conditioning of inspired air, so that a distinct phenotype of “sports asthma” has been proposed to characterise such athletes, who more often practise aquatic and winter sports. Overall, endurance training is good for health but may become deleterious when performed at high intensity or volume. PMID:27408632
Johnson, Robert M.
The purpose of this study was to determine the effects of manual negative accentuated resistance on strength and/or muscular endurance. Three strength and/or muscular endurance tests were administered to male and female physical education majors enrolled in a required exercise class at the beginning and end of the semester. Push-ups, chin-ups, and…
W. Harl, Tulane University ............................................................................... 4-1 “1066 and All That”: English and...Islamic invasion England vs. France (1066 to 1453, the Middle Ages) The 1066 Norman conquest of France English defeat that saw their military...1453) The creation of powerful centralized proto- states (as in Hundred Years’ War) Total English defeat 1-11 Introduction to Enduring Strategic
Haramizu, Satoshi; Ota, Noriyasu; Otsuka, Atsuko; Hashizume, Kohjiro; Sugita, Satoshi; Hase, Tadashi; Murase, Takatoshi; Shimotoyodome, Akira
Milk fat globule membrane (MFGM) comprises carbohydrates, membrane-specific proteins, glycoproteins, phospholipids, and sphingolipids. We evaluated the effects of MFGM consumption over a 12-wk period on endurance capacity and energy metabolism in BALB/c mice. Long-term MFGM intake combined with regular exercise improved endurance capacity, as evidenced by swimming time until fatigue, in a dose-dependent manner. The effect of dietary MFGM plus exercise was accompanied by higher oxygen consumption and lower respiratory quotient, as determined by indirect calorimetry. MFGM intake combined with exercise increased plasma levels of free fatty acids after swimming. After chronic intake of MFGM combined with exercise, the triglyceride content in the gastrocnemius muscle increased significantly. Mice given MFGM combined with exercise had higher mRNA levels of peroxisome proliferator-activated receptor-γ coactivator 1α (Pgc1α) and CPT-1b in the soleus muscle at rest, suggesting that increased lipid metabolism in skeletal muscle contributes, in part, to improved endurance capacity. MFGM treatment with cyclic equibiaxial stretch consisting of 10% elongation at 0.5 Hz with 1 h on and 5 h off increased the Pgc1α mRNA expression of differentiating C2C12 myoblasts in a dose-dependent manner. Supplementation with sphingomyelin increased endurance capacity in mice and Pgc1α mRNA expression in the soleus muscle in vivo and in differentiating myoblasts in vitro. These results indicate that dietary MFGM combined with exercise improves endurance performance via increased lipid metabolism and that sphingomyelin may be one of the components responsible for the beneficial effects of dietary MFGM.
Ortega, Francisco; Toral, Javier; Cejudo, Pilar; Villagomez, Rafael; Sánchez, Hildegard; Castillo, José; Montemayor, Teodoro
We determined the effect of different exercise training modalities in patients with chronic obstructive pulmonary disease, including strength training (n = 17), endurance training (n = 16), and combined strength and endurance (n = 14) (half of the endurance and half of the strengthening exercises). Data were compared at baseline, the end of the 12-week exercise-training program, and 12 weeks later. Improvement in the walking distance was only significant in the strength group. Increases in submaximal exercise capacity for the endurance group were significantly higher than those observed in the strength group but were of similar magnitude than those in the combined training modality, which in turn were significantly higher than for the strength group. Increases in the strength of the muscle groups measured in five weight lifting exercises were significantly higher in the strength group than in the endurance group but were of similar magnitude than in the combined training group, which again showed significantly higher increases than subjects in the endurance group. Any training modality showed significant improvements of the breathlessness score and the dyspnea dimension of the chronic respiratory questionnaire. In conclusion, the combination of strength and endurance training seems an adequate training strategy for chronic obstructive pulmonary disease patients.
Goulet, Eric D B; Dionne, Isabelle J
The use of nutritional ergogenic aids containing Eleutherococcus senticosus (ES), a plant which is also known as ciwujia or Siberian ginseng, is relatively common among endurance athletes. Eleutherococcus senticosus has been suggested to improve cardiorespiratory fitness (CF) and fat metabolism (FAM) and, therefore, endurance performance (EP). This article reviews the studies that evaluated the effects of ES during endurance exercise, three of which suggest that ES substantially improves CF, FAM, and EP. However, each of these reports contains severe methodological flaws, which seriously threaten their internal validity, thereby rendering hazardous the generalization of the results. On the other hand, 5 studies that used rigorous research protocols show no benefit of ES on CF, FAM, and EP. It is therefore concluded that ES supplementation (up to 1000 to 1200 mg/d for 1 to 6 wk) offers no advantage during exercise ranging in duration from 6 to 120 min.
Haggett, Emily; Magdesian, K Gary; Maas, John; Puschner, Birgit; Higgins, Jamie; Fiack, Ciara
Exercise causes an increase in the production of reactive oxygen species, which can result in oxidant/antioxidant disequilibrium. Deficiency of antioxidants can further alter this balance in favor of pro-oxidation. Selenium (Se) is one of many antioxidant catalysts, as a component of the glutathione peroxidase enzymes. Soils and forages vary widely in Se concentration and a deficient diet can lead to sub-clinical or clinical deficiency in horses. Endurance horses are prone to oxidative stress during long periods of aerobic exercise and their performance could be affected by Se status. This study investigated the blood Se concentration in a group of endurance horses (n=56) residing and competing in California, a state containing several regions that tend to produce Se-deficient forages. The rate of Se deficiency in this group of horses was low, with only one horse being slightly below the reference range. Higher blood Se concentrations were not associated with improved performance in terms of ride time. There was no significant difference in Se concentration between horses that completed the ride and those that were disqualified, although blood Se concentrations were significantly higher in horses that received oral Se supplementation. An increase in blood Se concentration was observed following exercise and this warrants further study.
Hawley, John A
In recent years, advances in molecular biology have allowed scientists to elucidate how endurance exercise training stimulates skeletal muscle remodeling (i.e. promotes mitochondrial biogenesis). A growing field of interest directly arising from our understanding of the molecular bases of training adaptation is how nutrient availability can alter the regulation of many contraction-induced events in muscle in response to endurance exercise. Acutely manipulating substrate availability can exert profound effects on muscle energy stores and patterns of fuel metabolism during exercise, as well as many processes activating gene expression and cell signaling. Accordingly, such interventions when repeated over weeks and months have the potential to modulate numerous adaptive processes in skeletal muscle that ultimately drive the phenotype-specific characteristics observed in highly trained athletes. In this review, the molecular and cellular events that occur in skeletal muscle during and after endurance exercise are discussed and evidence provided to demonstrate that nutrient availability plays an important role in modulating many of the adaptive responses to training. Emphasis is on human studies that have determined the regulatory role of muscle glycogen availability on cell metabolism, endurance training capacity and performance.
Couto, Mariana; Silva, Diana; Delgado, Luis; Moreira, André
Olympic level athletes present an increased risk for asthma and allergy, especially those who take part in endurance sports, such as swimming or running, and in winter sports. Classical postulated mechanisms behind EIA include the osmotic, or airway-drying, hypothesis. Hyperventilation leads to evaporation of water and the airway surface liquid becomes hyperosmolar, providing a stimulus for water to move from any cell nearby, which results in the shrinkage of cells and the consequent release of inflammatory mediators that cause airway smooth muscle contraction. But the exercise-induced asthma/bronchoconstriction explanatory model in athletes probably comprises the interaction between environmental training factors, including allergens and ambient conditions such as temperature, humidity and air quality; and athlete's personal risk factors, such as genetic and neuroimmuneendocrine determinants. After the stress of training and competitions athletes experience higher rate of upper respiratory tract infections (URTI), compared with lesser active individuals. Increasing physical activity in non-athletes is associated with a decreased risk of URTI. Heavy exercise induces marked immunodepression which is multifactorial in origin. Prolonged, high intensity exercise temporarily impairs the immune competence while moderate activity may enhance immune function. The relationship between URTI and exercise is affected by poorly known individual determinants such genetic susceptibility, neurogenic mediated immune inflammation and epithelial barrier dysfunction. Further studies should better define the aetiologic factors and mechanisms involved in the development of asthma in athletes, and propose relevant preventive and therapeutic measures.
Vasilyev, P. V.
An analysis of published data are presented as well as the results of experiments which show that the state of weightlessness and hypodynamia result in a reduced orthostatic and vestibular resistance, increased sensitivity to infections, decreased endurance of accelerations and physical exercises, and altered reactivity of the organism to drugs. Various consequences of weightlessness on the human body, especially weightlessness combined with other factors linked to long space flights are also considered.
von Duvillard, Serge P; Arciero, Paul J; Tietjen-Smith, Tara; Alford, Ken
A plethora of investigations examining fluid intake before, during, and after training and competition have suggested that a lack of adequate fluid intake will impair or decrease physical performance. Depending upon the type of training or competition, individuals training for prolonged endurance events should drink fluids containing carbohydrates and electrolytes during and after training or competition. Inadequate hydration will cause significant decrements in performance, increase thermal stress, reduce plasma volume, accelerate fatigue, and possibly cause injuries associated with fluid and sweat loss. However, overdrinking may cause Na+ depletion and in some cases lead to hyponatremia. Maintaining proper hydration before, during, and after training and competition will help reduce fluid loss, maintain performance, lower submaximal exercise heart rate, maintain plasma volume, and reduce heat stress, heat exhaustion, and possibly heat stroke.
Takii, H; Ishihara, K; Kometani, T; Okada, S; Fushiki, T
We investigated the ergogenic effect in mice of administering highly branched cyclic dextrin (HBCD), a new type of glucose polymer, on the swimming endurance in an adjustable-current swimming pool. Male Std ddY mice were administered a HBCD, a glucose solution or water via a stomach sonde 10 min before, 10 min after or 30 min after beginning swimming exercise, and were then obliged to swim in the pool. The total swimming period until exhaustion, an index of the swimming endurance, was measured. An ergogenic effect of HBCD was observed at a dose of 500 mg/kg of body weight, whereas it had no effect at a dose of 166 mg/kg of body wt (p < 0.05). The mice administered with the HBCD solution 10 min after starting the exercise were able to swim significantly longer (p < 0.05) than the mice who had ingested water or the glucose solution. The rise in mean blood glucose level in the mice administered with HBCD, which was measured 20 min after starting swimming, was significantly lower (p < 0.05) than that in the mice administered with glucose, although it was significantly higher (p < 0.05) than that in the mice administered with water. The mean blood insulin rise in the mice given HBCD was significantly lower (p < 0.05) than that in the mice given glucose. The mice administered with HBCD 30 min after starting the exercise swam significantly longer (p < 0.05) than the mice who had ingested water, although the enhancement of swimming time was similar to that of the glucose-ingesting mice. The gastric emptying rate of the HBCD solution was significantly faster (p < 0.05) than that of the glucose solution. However, this glucose polymer must have spent more time being absorbed because it has to be hydrolyzed before absorption, reflecting a lower and possibly longer-lasting blood glucose level. We conclude that the prolongation of swimming endurance in mice administered with HBCD depended on its rapid and longer-lasting ability for supplying glucose with a lower postprandial
2004-01-01This image shows the approximate size of the Mars Exploration Rover Opportunity in comparison to the impressive impact crater dubbed 'Endurance,' which is roughly 130 meters (430 feet) across. A model of Opportunity has been superimposed on top of an approximate true-color image taken by the rover's panoramic camera. Scientists are eager to explore Endurance for clues to the red planet's history. The crater's exposed walls provide a window to what lies beneath the surface of Mars and thus what geologic processes occurred there in the past. While recent studies of the smaller crater nicknamed 'Eagle' revealed an evaporating body of salty water, that crater was not deep enough to indicate what came before the water. Endurance may be able to help answer this question, but the challenge is getting to the scientific targets: most of the crater's rocks are embedded in vertical cliffs. Rover planners are developing strategies to overcome this obstacle. This image is a portion of a larger mosaic taken with the panoramic camera's 480-, 530- and 750-nanometer filters on sols 97 and 98.
Jung, Hoe-Yune; Lee, An-Na; Song, Tae-Jun; An, Hyo-Sun; Kim, Young-Hoon; Kim, Kyu-Dae; Kim, In-Bo; Kim, Kyoung-Shim; Han, Baek-Soo; Kim, Chun-Hyung; Kim, Kwang-Soo; Kim, Jong-Bae
The beneficial effects of exercise on overall health make it desirable to identify the orally active agents that enhance the effects of exercise in an effort to cure metabolic diseases. Natural compounds such as resveratrol (RSV) are known to increase endurance by potentiating mitochondrial function. Korean mistletoe (Viscum album coloratum) extract (KME) has characteristics similar to those of RSV. In the present study, we determined whether KME could increase mitochondrial activity and exert an anti-fatigue effect. We found that KME treatment significantly increased the mitochondrial oxygen consumption rate (OCR) in L6 cells and increased the expression of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and silent mating type information regulation 2 homolog 1 (SIRT1), two major regulators of mitochondria function, in C2C12 cells. In the treadmill test, KME-treated mice could run 2.5-times longer than chow-fed control mice. Additionally, plasma lactate levels of exhausted mice were significantly lower in the KME-treated group. In addition, the swimming time to exhaustion of mice treated with KME was prolonged by as much as 212% in the forced-swim test. Liver and kidney histology was similar between the KME-treated and phosphate-buffered saline-treated animals, indicating that KME was nontoxic. Taken together, our data show that KME induces mitochondrial activity, possibly by activating PGC-1α and SIRT1, and improves the endurance of mice, strongly suggesting that KME has great potential as a novel mitochondria-activating agent.
Raboin, Jasen; Niebuhr, Jason; Cruz, Santana; Lamoreaux, chris
The advanced resistive exercise device (ARED), now at the prototype stage of development, is a versatile machine that can be used to perform different customized exercises for which, heretofore, it has been necessary to use different machines. Conceived as a means of helping astronauts and others to maintain muscle and bone strength and endurance in low-gravity environments, the ARED could also prove advantageous in terrestrial settings (e.g., health clubs and military training facilities) in which many users are exercising simultaneously and there is heavy demand for use of exercise machines.
Saunders, Philo U; Pyne, David B; Gore, Christopher J
Since the 1968 Olympic Games when the effects of altitude on endurance performance became evident, moderate altitude training ( approximately 2000 to 3000 m) has become popular to improve competition performance both at altitude and sea level. When endurance athletes are exposed acutely to moderate altitude, a number of physiological responses occur that can comprise performance at altitude; these include increased ventilation, increased heart rate, decreased stroke volume, reduced plasma volume, and lower maximal aerobic power ((.)Vo(2max)) by approximately 15% to 20%. Over a period of several weeks, one primary acclimatization response is an increase in the volume of red blood cells and consequently of (.)Vo(2max). Altitudes > approximately 2000 m for >3 weeks and adequate iron stores are required to elicit these responses. However, the primacy of more red blood cells for superior sea-level performance is not clear-cut since the best endurance athletes in the world, from Ethiopia (approximately 2000 to 3000 m), have only marginally elevated hemoglobin concentrations. The substantial reduction in (.)Vo(2max) of athletes at moderate altitude implies that their training should include adequate short-duration (approximately 1 to 2 min), high-intensity efforts with long recoveries to avoid a reduction in race-specific fitness. At the elite level, athlete performance is not dependent solely on (.)Vo(2max), and the "smallest worthwhile change" in performance for improving race results is as little as 0.5%. Consequently, contemporary statistical approaches that utilize the concept of the smallest worthwhile change are likely to be more appropriate than conventional statistical methods when attempting to understand the potential benefits and mechanisms of altitude training.
2004-01-01The colored dots in this image mosaic denote thermal data in features that make up the impact crater known as 'Endurance.' The data was taken by the miniature thermal emission spectrometer instrument on NASA's Mars Exploration Rover Opportunity. The information has been overlaid onto a view of the crater from the rover's navigation camera. Blue denotes cooler temperatures of about 220 degrees Kelvin (-63.67 degrees Fahrenheit or -53.15 degrees Celsius), and red denotes warmer temperatures of about 280 degrees Kelvin (44.33 degrees Fahrenheit or 6.85 degrees Celsius).
2004-01-01This false-color image shows visible mineral changes between the materials that make up the rim of the impact crater known as 'Endurance.' The image was taken by the panoramic camera on NASA's Mars Exploration Rover Opportunity using all 13 color filters. The cyan blue color denotes basalts, whereas the dark green color denotes a mixture of iron oxide and basaltic materials. Reds and yellows indicate dusty material containing sulfates. Scientists are very interested in exploring the interior and exterior material around the crater's rim for clues to the processes that formed the crater, as well as the rocks and textures that define the crater.
2004-01-01This view of rock layers exposed in the upper portion of the inner slope of 'Endurance Crater' was captured by the navigation camera on NASA's Mars Exploration Rover Opportunity from the rover's position inside the crater during Opportunity's 134th sol on June 9, 2004. Scientists and engineers are assessing possible targets and routes among these rocks. The view is looking down into the crater, so the layers at the top of the image lie lower in the crater than the rocks in the foreground.
2004-01-01This image taken by the Mars Exploration Rover Opportunity shows a bizarre, lumpy rock dubbed 'Wopmay' on the inner slopes of 'Endurance Crater.' Scientists say the rock's unusual texture is unlike any others observed so far at Meridiani Planum. Wopmay measures approximately 1 meter (3.3 feet) across. The image was taken by the rover's panoramic camera on sol 195 (Aug. 11, 2004). Opportunity will likely travel to this or a similar rock in coming sols for a closer look at the alien surface.
Tsiloulis, Thomas; Watt, Matthew J
Adipose tissue is a major regulator of metabolism in health and disease. The prominent roles of adipose tissue are to sequester fatty acids in times of energy excess and to release fatty acids via the process of lipolysis during times of high-energy demand, such as exercise. The fatty acids released during lipolysis are utilized by skeletal muscle to produce adenosine triphosphate to prevent fatigue during prolonged exercise. Lipolysis is controlled by a complex interplay between neuro-humoral regulators, intracellular signaling networks, phosphorylation events involving protein kinase A, translocation of proteins within the cell, and protein-protein interactions. Herein, we describe in detail the cellular and molecular regulation of lipolysis and how these processes are altered by acute exercise. We also explore the processes that underpin adipocyte adaptation to endurance exercise training, with particular focus on epigenetic modifications, control by microRNAs and mitochondrial adaptations. Finally, we examine recent literature describing how exercise might influence the conversion of traditional white adipose tissue to high energy-consuming "brown-like" adipocytes and the implications that this has on whole-body energy balance.
This study investigated the effects of 30 minutes of endurance jogging on pulse rates at rest, during exercise, and at recovery and eight skinfold fat measures in middle-aged women. Subjects were 15 middle-aged women between 30 and 58 years of age who had not been engaged in any exercise program at least for 1 year. Eight sedentary subjects were…
Shaw, Brandon S; Shaw, Ina; Brown, Gregory A
Resistance and endurance training are often performed concurrently in most exercise programs and in rehabilitative settings in an attempt to acquire gains in more than 1 physiologic system. However, it has been proposed that by simultaneously performing these 2 modes of exercise training, the strength gains achieved by resistance training alone may be impaired. Thus, the aim of this study was to compare the effects of 16 weeks of resistance training and concurrent resistance and endurance training on muscular strength development in 38 sedentary, apparently healthy males (25 yr +/- 8 mo). Subjects were age-matched and randomly assigned to either a control (Con) group (n = 12), resistance training (Res) group (n = 13), or concurrent resistance and endurance training (Com) group (n = 13). After 16 weeks, no changes were found in the strength of the subjects in the Con group. Resistance training and concurrent resistance and endurance training significantly (p < or = 0.05) improved strength in all of the 8 prescribed exercises. The data also indicated that 16 weeks of concurrent resistance training and endurance training was as effective in eliciting improvements in strength as resistance training alone in previously sedentary males. As such, concurrent resistance and endurance training does not impede muscular strength gains and can be prescribed simultaneously for the development of strength in sedentary, apparently healthy males and thus may invoke all the physiologic adaptations of resistance and endurance training at once.
Exercise and physical activity are good for just about everyone, including older adults. There are four main types and each type is different. Doing them all will give you more benefits. Endurance, or aerobic, activities increase your breathing and heart rate. Brisk walking or jogging, dancing, swimming, ...
Sharma, Sanjay; Merghani, Ahmed; Mont, Lluis
The benefits of exercise are irrefutable. Individuals engaging in regular exercise have a favourable cardiovascular risk profile for coronary artery disease and reduce their risk of myocardial infarction by 50%. Exercise promotes longevity of life, reduces the risk of some malignancies, retards the onset of dementia, and is as considered an antidepressant. Most of these benefits are attributable to moderate exercise, whereas athletes perform way beyond the recommended levels of physical activity and constantly push back the frontiers of human endurance. The cardiovascular adaptation for generating a large and sustained increase in cardiac output during prolonged exercise includes a 10-20% increase in cardiac dimensions. In rare instances, these physiological increases in cardiac size overlap with morphologically mild expressions of the primary cardiomyopathies and resolving the diagnostic dilemma can be challenging. Intense exercise may infrequently trigger arrhythmogenic sudden cardiac death in an athlete harbouring asymptomatic cardiac disease. In parallel with the extraordinary athletic milieu of physical performances previously considered unachievable, there is emerging data indicating that long-standing vigorous exercise may be associated with adverse electrical and structural remodelling in otherwise normal hearts. Finally, in the current era of celebrity athletes and lucrative sport contracts, several athletes have succumbed to using performance enhancing agents for success which are detrimental to cardiac health. This article discusses the issues abovementioned, which can be broadly classified as the good, bad, and ugly aspects of sports cardiology.
Amann, Markus; Romer, Lee M; Subudhi, Andrew W; Pegelow, David F; Dempsey, Jerome A
We examined the effects of hypoxia severity on peripheral versus central determinants of exercise performance. Eight cyclists performed constant-load exercise to exhaustion at various fractions of inspired O2 fraction (FIO2 0.21/0.15/0.10). At task failure (pedal frequency < 70% target) arterial hypoxaemia was surreptitiously reversed via acute