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Sample records for 1000-hour endurance test

  1. Free-piston Stirling engine/linear alternator 1000-hour endurance test

    NASA Technical Reports Server (NTRS)

    Rauch, J.; Dochat, G.

    1985-01-01

    The Free Piston Stirling Engine (FPSE) has the potential to be a long lived, highly reliable, power conversion device attractive for many product applications such as space, residential or remote site power. The purpose of endurance testing the FPSE was to demonstrate its potential for long life. The endurance program was directed at obtaining 1000 operational hours under various test conditions: low power, full stroke, duty cycle and stop/start. Critical performance parameters were measured to note any change and/or trend. Inspections were conducted to measure and compare critical seal/bearing clearances. The engine performed well throughout the program, completing more than 1100 hours. Hardware inspection, including the critical clearances, showed no significant change in hardware or clearance dimensions. The performance parameters did not exhibit any increasing or decreasing trends. The test program confirms the potential for long life FPSE applications.

  2. Production Facility Prototype Blower 1000 Hour Test Results

    SciTech Connect

    Woloshun, Keith Albert; Dale, Gregory E.; Romero, Frank Patrick; Dalmas, Dale Allen

    2016-10-18

    The roots blower in use at ANL for in-beam experiments and also at LANL for flow tests was sized for 12 mm diameter disks and significantly less beam heating. Currently, the disks are 29 mm in diameter, with a 12 mm FWHM Gaussian beam spot at 42 MeV and 2.86 μA on each side of the target, 5.72 μA total. The target design itself is reported elsewhere. With the increased beam heating, the helium flow requirement increased so that a larger blower was needed for a mass flow rate of 400 g/s at 2.76 MPa (400 psig). An Aerzen GM 12.4 blower was selected, and is now installed at the LANL facility for target and component flow testing. Two extended tests of >1000 hr operation have been completed. Those results and discussion thereof are reported herein. Also included in Appendix A is the detailed description of the blower and its installation, while Appendix B documents the pressure vessel design analysis. The blower has been operated for 1000 hours as a preliminary investigation of long-term performance, operation and possible maintenance issues. The blower performed well, with no significant change in blower head or mass flow rate developed under the operating conditions. Upon inspection, some oil had leaked out of the shaft seal of the blower. The shaft seal and bearing race have been replaced. Test results and conclusions are in Appendix B.

  3. Results of a 1000-hour wear test of 30-cm carbon-carbon ion optics

    NASA Technical Reports Server (NTRS)

    Snyder, John Steven; Brophy, John R.; Anderson, John R.

    2005-01-01

    This paper discusses the results of a 1000-hour wear test intended to determine the erosion resistance and voltage standoff capability of the optics in a relevant environment, i.e. duration testing on an NSTAR-like thruster.

  4. Production Facility Prototype Blower Installation Report with 1000 Hour Test Results

    SciTech Connect

    Woloshun, Keith Albert; Dale, Gregory E.; Romero, Frank Patrick; Dalmas, Dale Allen

    2016-04-01

    The roots blower in use at ANL for in-beam experiments and also at LANL for flow tests was sized for 12 mm diameter disks and significantly less beam heating. Currently, the disks are 29 mm in diameter, with a 12 mm FWHM Gaussian beam spot at 42 MeV and 2.86 μA on each side of the target, 5.72 μA total. The target design itself is reported elsewhere. With the increased beam heating, the helium flow requirement increased so that a larger blower was needed for a mass flow rate of 400 g/s at 2.76 MPa (400 psig). An Aerzen GM 12.4 blower was selected, and is currently being installed at the LANL facility for target and component flow testing. This report describes this blower/motor/pressure vessel package and the status of the facility preparations. The blower has been operated for 1000 hours as a preliminary investigation of long term performance, operation and possible maintenance issues. The blower performed well, with no significant change in blower head or mass flow rate developed under the operating conditions. Upon inspection, some oil had leaked out of the shaft seal of the blower. The shaft seal and bearing race have been replaced. Test results and conclusions are reported.

  5. Evaluation of candidate Stirling engine heater tube alloys for 1000 hours at 760 C

    NASA Technical Reports Server (NTRS)

    Misencik, J. A.

    1980-01-01

    Six tubing alloys were endurance tested in a diesel fired, Stirling engine simulator materials test rig for 1000 hours of 760 C while pressurized at 17 to 21 MPa with either hydrogen or helium. The alloys tested were N 155, A 286, Incoloy 800, 19 9DL, Nitronic 40 and 316 stainless steel. The alloys were in the form of thin wall tubing. Hydrogen permeated rapidly through the tube walls of all six alloys when they were heated to 760 C. Helium was readily contained. Creep rupture failures occurred in four of the six alloys pressurized with hydrogen. Only two alloys survived the 1000 hour endurance test with no failures. Simultaneous exposure to either hydrogen or helium and the combustion environment did not seriously degrade the tensile strength of the six alloys in room temperature or 760 C tests after exposure. Decreases in room temperature ductility were observed and are attributed to aging rather than to hydrogen embrittlement in three of the alloys. However, there may be a hydrogen embrittlement effect in the N 155, 19 9DL, and Nitronic 40 alloys.

  6. Free-piston stirling engine endurance test program

    NASA Technical Reports Server (NTRS)

    Dochat, G.; Rauch, J.; Antonelli, G.

    1983-01-01

    The Free-Piston Stirling Engine (FPSE) has the potential to be a long-lived, highly reliable, power conversion device attractive for many product applications such as space, residential, or remote-site power. The purpose of endurance testing the FPSE is to demonstrate its potential for long life. The endurance program was directed at obtaining 1000 operational hours under various test conditions: low power, full stroke, duty cycle, and stop/start. Critical performance parameters were measured to note any change and/or trend. Inspections were conducted to measure and compare critical seal/bearing clearance. The engine performed well throughout the program, completing the 1000 hours. Hardware inspection, including the critical clearances, showed no significant change in hardware or clearance dimensions. The performance parameters did not exhibit any increasing or decreasing trends. The test program confirms the potential for long-life FPSE applications. Additional testing is planned to increase the test hours to 10,000.

  7. Report of 1,000 Hour Catalyst Longevity Evaluation

    SciTech Connect

    Daniel M. Ginosar

    2009-06-01

    This report presents the results of a 1,000 hour, high-pressure, catalyst longevity test for the decomposition of concentrated sulfuric acid. The reaction is used for both the sulfur-iodine (S-I) cycle and hybrid sulfur cycle. By the time of the delivery date of April 17, 2009, for project milestone no. 2NIN07TC050114, the 1% Pt/TiO2 catalyst had been in the reaction environment for 658 hours. During the first 480 hours of testing, the catalyst activity provided stable, near-equilibrium yields of 46.8% SO2 and 22.8% O2. However, product yields declined at sample exposure times >480 hours. At 658 hours of operation, catalyst activity (based on oxygen yield) declined to 57% relative to the stable period of catalyst activity. Thus, as of April 17, this catalyst did not provide the desired stability level of <10% degradation per 1,000 hours. The experiment was terminated on April 27, after 792 hours, when a fitting failed and the catalyst was displaced from the reactor such that the sample could not be recovered. Oxygen conversion at the end of the experiment was 12.5% and declining, suggesting that at that point, catalyst activity had decreased to 54% of the initial level.

  8. 14 CFR 35.39 - Endurance test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Endurance test. 35.39 Section 35.39... STANDARDS: PROPELLERS Tests and Inspections § 35.39 Endurance test. Endurance tests on the propeller system... propellers must be subjected to one of the following tests: (1) A 50-hour flight test in level flight or...

  9. 14 CFR 35.39 - Endurance test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Endurance test. 35.39 Section 35.39... STANDARDS: PROPELLERS Tests and Inspections § 35.39 Endurance test. Endurance tests on the propeller system... propellers must be subjected to one of the following tests: (1) A 50-hour flight test in level flight or...

  10. 14 CFR 35.39 - Endurance test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Endurance test. 35.39 Section 35.39... STANDARDS: PROPELLERS Tests and Inspections § 35.39 Endurance test. Endurance tests on the propeller system... propellers must be subjected to one of the following tests: (1) A 50-hour flight test in level flight or...

  11. 14 CFR 33.87 - Endurance test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Endurance test. 33.87 Section 33.87... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.87 Endurance test. (a) General. Each engine must be subjected to an endurance test that includes a total of at least 150 hours of...

  12. 14 CFR 33.87 - Endurance test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Endurance test. 33.87 Section 33.87... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.87 Endurance test. (a) General. Each engine must be subjected to an endurance test that includes a total of at least 150 hours of...

  13. 14 CFR 33.49 - Endurance test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Endurance test. 33.49 Section 33.49... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.49 Endurance test. (a) General. Each engine must be subjected to an endurance test that includes a total of 150 hours of...

  14. 14 CFR 33.49 - Endurance test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Endurance test. 33.49 Section 33.49... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.49 Endurance test. (a) General. Each engine must be subjected to an endurance test that includes a total of 150 hours of...

  15. 14 CFR 33.49 - Endurance test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Endurance test. 33.49 Section 33.49... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.49 Endurance test. (a) General. Each engine must be subjected to an endurance test that includes a total of 150 hours of...

  16. 14 CFR 33.87 - Endurance test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Endurance test. 33.87 Section 33.87... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.87 Endurance test. (a) General. Each engine must be subjected to an endurance test that includes a total of at least 150 hours of...

  17. CATCOM catalyst 5 atm 1000 hour aging study using No. 2 fuel oil

    NASA Technical Reports Server (NTRS)

    Osgerby, I. T.; Olson, B. A.; Lee, H. C.

    1980-01-01

    The durability of the CATCOM catalyst for use in catalytically supported thermal combustion has been demonstrated at 5 atm, complementing a previous 1000 hour durability study at 1 atm. Both of these studies were conducted at about 640 K air preheat temperature at a reference velocity of about 14 m/s; the adiabatic flame temperature of the fuel/air mixture was about 1530 K. The catalyst proved to be capable of low emissions operations after 1000 hours of diesel fuel aging. However, more severe deactivation occurred in the 5 atm test; this was attributed to a loss in kinetic (ignition) activity.

  18. 14 CFR 33.87 - Endurance test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.87 Endurance test. (a) General. Each... power turbine rotor assembly to the engine shaft output. (7) During the runs at any rated power or... engines with augmented takeoff power ratings that involve increases in turbine inlet temperature,...

  19. 14 CFR 33.49 - Endurance test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) of this section at 80 percent of rated maximum continuous power must be made at 8,000 feet altitude... takeoff power and for at least 35 hours at rated maximum continuous power, one cylinder must be operated... shaft must be fitted for the endurance test with a propeller that thrust-loads the engine to the...

  20. 14 CFR 33.49 - Endurance test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) of this section at 80 percent of rated maximum continuous power must be made at 8,000 feet altitude... takeoff power and for at least 35 hours at rated maximum continuous power, one cylinder must be operated... shaft must be fitted for the endurance test with a propeller that thrust-loads the engine to the...

  1. Endurance testing with Li/Na electrolyte

    SciTech Connect

    Ong, E.T.; Remick, R.J.; Sishtla, C.I.

    1996-12-31

    The Institute of Gas Technology (IGT), under subcontract to M-C Power Corporation under DOE funding, has been operating bench-scale fuel cells to investigate the performance and endurance issues of the Li/Na electrolyte because it offers higher ionic conductivity, higher exchange current densities, lower vapor pressures, and lower cathode dissolution rates than the Li/K electrolyte. These cells have continued to show higher performance and lower decay rates than the Li/K cells since the publication of our two previous papers in 1994. In this paper, test results of two long-term 100-cm{sup 2} bench scale cells are discussed. One cell operated continuously at 160 mA/cm{sup 2} for 17,000 hours with reference gases (60H{sub 2}/20CO{sub 2}/20H{sub 2}O fuel at 75% utilization and 30CO{sub 2}/70 air oxidant humidified at room temperature at 50% utilization). The other cell operated at 160 mA/cm{sup 2} for 6900 hours at 3 atm with system gases (64H{sub 2}/16CO{sub 2}/20H{sub 2}O at 75% utilization and an M-C Power system-defined oxidant at 40% utilization). Both cells have shown the highest performance and longest endurance among IGT cells operated to date.

  2. Endurance testing of a 30-cm Kaufman thruster

    NASA Technical Reports Server (NTRS)

    Collett, C. R.

    1973-01-01

    Results of a program to demonstrate lifetime capability of a 30-cm Kaufman ion thruster with a 6000 hour endurance test are described. Included in the program are (1) thruster fabrication, (2) design and construction of a test console containing a transistorized high frequency power processor, and control circuits which provide unattended automatic operation of the thruster, and (3) modification of a vacuum facility to incorporate a frozen mercury collector and permit unattended operation. Four tests ranging in duration from 100 to 1100 hours have been completed. These tests and the resulting thruster modifications are described. The status of the endurance test is also presented.

  3. A Field Test for Upper Body Strength and Endurance.

    ERIC Educational Resources Information Center

    Nelson, Jack K.; And Others

    1991-01-01

    Researchers studied the reliability of the modified push-up test in measuring upper body strength and endurance in elementary through college students. It also examined the accuracy of partner scoring. The test proved much easier to administer than the regular floor push-up. It was valid and reliable for all students and suitable for partner…

  4. Comparison between three different endurance tests in professional soccer players.

    PubMed

    Hoppe, Matthias W; Baumgart, Christian; Sperlich, Billy; Ibrahim, Hassan; Jansen, Christian; Willis, Sarah J; Freiwald, Juergen

    2013-01-01

    The aims of this study were (a) to assess and correlate interval shuttle run test (ISRT) performance, maximum oxygen uptake (V[Combining Dot Above]O(2)max), running economy (RE), running velocity at the first rise in blood lactate concentrations above baseline (vLT) and running velocity at 4 mmol·L(-1) blood lactate concentration (v4) in professional soccer players and (b) to investigate whether a correlation exists between the respective results of time to exhaustion (T(lim)) from continuous and intermittent endurance tests, respectively. Eleven male professional field soccer players (mean ± SD: age 23.8 ± 3.0 years, V[Combining Dot Above]O(2)max 58.2 ± 4.9 ml·kg(-1)·min(-1)) completed a continuous Incremental Test with lactate measurements to determine vLT and v4, a continuous Ramp Test with gas exchange analysis to determine V[Combining Dot Above]O(2)max and RE, and an intermittent ISRT to determine intermittent endurance capacity during the first week of preseason preparation. There were significant correlations between ISRT performance and V[Combining Dot Above]O(2)max (r = 0.70, p < 0.05), and between T(lim) in both continuous endurance tests (r = 0.89, p < 0.01). Between all other variables no significant correlations were found overall (best r = 0.60, p > 0.05). The assessment of all values of V[Combining Dot Above]O(2)max, RE, vLT, and v4 should be included when investigating aerobic endurance performance among groups or over time in professional soccer players. Although V[Combining Dot Above]O(2)max, RE, vLT, and v4 have been regarded as important factors of aerobic performance in endurance related sports, the present data revealed that V[Combining Dot Above]O(2)max was the only factor, which correlated with intermittent endurance capacity in professional soccer players. Hence, V[Combining Dot Above]O(2)max should be increased through soccer-specific training interventions including universal agility components. The T(lim) in continuous and

  5. Ion thruster system (8-cm) cyclic endurance test

    NASA Technical Reports Server (NTRS)

    Dulgeroff, C. R.; Beattie, J. R.; Poeschel, R. L.; Hyman, J., Jr.

    1984-01-01

    This report describes the qualification test of an Engineering-Model 5-mN-thrust 8-cm-diameter mercury ion thruster which is representative of the Ion Auxiliary Propulsion System (IAPS) thrusters. Two of these thrusters are scheduled for future flight test. The cyclic endurance test described herein was a ground-based test performed in a vacuum facility with a liquid-nitrogen-cooled cryo-surface and a frozen mercury target. The Power Electronics Unit, Beam Shield, Gimal, and Propellant Tank that were used with the thruster in the endurance test are also similar to those of the IAPS. The IAPS thruster that will undergo the longest beam-on-time during the actual space test will be subjected to 7,055 hours of beam-on-time and 2,557 cycles during the flight test. The endurance test was successfully concluded when the mercury in the IAPS Propellant Tank was consumed. At that time, 8,471 hours of beam-on-time and 599 cycles had been accumulated. Subsequent post-test-evaluation operations were performed (without breaking vacuum) which extended the test values to 652 cycles and 9,489 hours of beam-on-time. The Power Electronic Unit (PEU) and thruster were in the same vacuum chamber throughout the test. The PEU accumulated 10,268 hr of test time with high voltage applied to the operating thruster or dummy load.

  6. Endurance Tests Of Amorphous-Silicon Photovoltaic Modules

    NASA Technical Reports Server (NTRS)

    Ross, Ronald G., Jr.; Sugimura, Russell S.

    1989-01-01

    Failure mechanisms in high-power service studied. Report discusses factors affecting endurance of amorphous-silicon solar cells. Based on field tests and accelerated aging of photovoltaic modules. Concludes that aggressive research needed if amorphous-silicon modules to attain 10-year life - value U.S. Department of Energy established as goal for photovoltaic modules in commercial energy-generating plants.

  7. Fire Endurance Testing of Fiberglass Piping

    DTIC Science & Technology

    1992-04-01

    explosion . A computer data acquisition system was used to record the various channels of test data. Color video cameras, an infrared camera, and 35 mm...sample included a bolted flanged coupling. One of the copper-nickel samples had a brazed sleeve-type coupling and the other had a Staub mechanical...FGP of the types tested. Pipe deflections were within IACS limits. 8. An explosion hazard exists when sealed pipe samples are exposed to fire. If the

  8. Wheeled and Tracked Vehicle Endurance Testing

    DTIC Science & Technology

    2014-10-02

    Range Bound will be the 90-Percent Range value from the Low Severity run. The upper Caution Zone 90-Percent Range Bound will be the 90-Percent Range ...upper Caution Zone bounds. A sample plot of the Left Front Suspension Acceleration 90-Percent Range Values and Caution and Control Bounds for a...SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) U.S. Army Test and Evaluation Command CSTE-TM ( Range Infrastructure Division) 2202 Aberdeen

  9. Analysis of Tests Evaluating Sport Climbers’ Strength and Isometric Endurance

    PubMed Central

    Ozimek, Mariusz; Staszkiewicz, Robert; Rokowski, Robert

    2016-01-01

    Abstract The present study was designed to determine which types of specific tests provide an effective evaluation of strength and endurance in highly trained competitive sport climbers. The research process consisted of three basic components: the measurement of selected somatic characteristics of the climbers, the assessment of their physical conditioning, and a search for correlations between the anthropometric and “conditioning” variables on the one hand, and climber’s performance on the other. The sample of subjects consisted of 14 experienced volunteer climbers capable of handling 7a- 8a+/b on-sight rock climbing grades. The strongest correlations (Spearman’s rank) were found between climber’s competence and the relative results of the finger strength test (r = 0.7); much lower, but still statistically significant coefficients were found between the level of competence and the results of the muscle endurance tests (r = 0.53 – 0.57). Climbers aspiring to attain an elite level must have strong finger and forearm muscles, but most of all, they must be capable of releasing their potential during specific motor capability tests engaging these parts of the body. The forearm muscles of elite climbers must also be very resistant to fatigue. Since highly trained athletes vary only slightly in body mass, this variable does not have a major effect on their performance during strength and endurance tests. PMID:28149428

  10. Analysis of Tests Evaluating Sport Climbers' Strength and Isometric Endurance.

    PubMed

    Ozimek, Mariusz; Staszkiewicz, Robert; Rokowski, Robert; Stanula, Arkadiusz

    2016-12-01

    The present study was designed to determine which types of specific tests provide an effective evaluation of strength and endurance in highly trained competitive sport climbers. The research process consisted of three basic components: the measurement of selected somatic characteristics of the climbers, the assessment of their physical conditioning, and a search for correlations between the anthropometric and "conditioning" variables on the one hand, and climber's performance on the other. The sample of subjects consisted of 14 experienced volunteer climbers capable of handling 7a- 8a+/b on-sight rock climbing grades. The strongest correlations (Spearman's rank) were found between climber's competence and the relative results of the finger strength test (r = 0.7); much lower, but still statistically significant coefficients were found between the level of competence and the results of the muscle endurance tests (r = 0.53 - 0.57). Climbers aspiring to attain an elite level must have strong finger and forearm muscles, but most of all, they must be capable of releasing their potential during specific motor capability tests engaging these parts of the body. The forearm muscles of elite climbers must also be very resistant to fatigue. Since highly trained athletes vary only slightly in body mass, this variable does not have a major effect on their performance during strength and endurance tests.

  11. Exercise responses during endurance testing at different intensities in patients with COPD.

    PubMed

    Oga, Toru; Nishimura, Koichi; Tsukino, Mitsuhiro; Sato, Susumu

    2004-06-01

    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.

  12. Endurance test of a 30-CM-diameter engineering model ion thruster. Task 12: Investigation of thin-film erosion monitors for ion thrusters

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.

    1983-01-01

    An investigation of short term measurement techniques for predicting the wearout of ion thrusters resulting from sputter erosion damage is described. The previously established laminar thin film techniques to provide high precision erosion rate data. However, the erosion rates obtained using this technique are generally substantially higher than those obtained during long term endurance tests (by virtue of the as deposited nature of the thin films), so that the results must be interpreted in a relative sense. Absolute measurements can be performed using a new masked substrate arrangement which was developed during this study. This new technique provides a means for estimating the lifetimes of critical discharge chamber components based on direct measurements of sputter erosion depths obtained during short duration (10 hour) tests. The method enables the effects on lifetime of thruster design and operating parameters to be inferred without the investment of the time and capital required to conduct long term (1000 hour) endurance tests. Results obtained using the direct measurement technique are shown to agree with sputter erosion depths calculated for the plasma conditions of the test and also with lifetest results. The direct measurement approach is shown to be applicable to both mercury and argon discharge plasma environments and should be useful in estimating the lifetimes of inert gas and extended performance mercury ion thrusters presently under development.

  13. Results of a 1462 hour ammonia arcjet endurance test

    NASA Astrophysics Data System (ADS)

    Polk, J. E.; Goodfellow, K. D.

    1992-07-01

    A total of 1462 hours of operaton were demonstrated in an endurance test of a 30 kWe-class ammonia arcjet operated at 10 kWe. The propellant flow rate was 0.170 g/s, and the measured performance increased from approximately 650 s specific impulse at 36 percent efficiency at the beginning of the test to 675 s at 39 percent near the end. The voltage increased and the current dropped slightly over the first 400 hours, and then remained approximately constant for the remainder of the test. The test, scheduled for 1500 hours, was terminated after an insulator in the rear of the engine failed. Post-test examination of the electrodes revealed only minimal damage. Although there was evidence of a number of mass transport processes occurring in the discharge chamber, the primary life-limiting wear mechanisms appear to be cathode tip erosion and constrictor melting.

  14. Results of a 1462 hour ammonia arcjet endurance test

    NASA Technical Reports Server (NTRS)

    Polk, J. E.; Goodfellow, K. D.

    1992-01-01

    A total of 1462 hours of operaton were demonstrated in an endurance test of a 30 kWe-class ammonia arcjet operated at 10 kWe. The propellant flow rate was 0.170 g/s, and the measured performance increased from approximately 650 s specific impulse at 36 percent efficiency at the beginning of the test to 675 s at 39 percent near the end. The voltage increased and the current dropped slightly over the first 400 hours, and then remained approximately constant for the remainder of the test. The test, scheduled for 1500 hours, was terminated after an insulator in the rear of the engine failed. Post-test examination of the electrodes revealed only minimal damage. Although there was evidence of a number of mass transport processes occurring in the discharge chamber, the primary life-limiting wear mechanisms appear to be cathode tip erosion and constrictor melting.

  15. Endurance Test and Evaluation of Alkaline Water Electrolysis Cells

    NASA Technical Reports Server (NTRS)

    Kovach, Andrew J.; Schubert, Franz H.; Chang, B. J.; Larkins, Jim T.

    1985-01-01

    The overall objective of this program is to assess the state of alkaline water electrolysis cell technology and its potential as part of a Regenerative Fuel Cell System (RFCS) of a multikilowatt orbiting powerplant. The program evaluates the endurance capabilities of alkaline electrolyte water electrolysis cells under various operating conditions, including constant condition testing, cyclic testing and high pressure testing. The RFCS demanded the scale-up of existing cell hardware from 0.1 sq ft active electrode area to 1.0 sq ft active electrode area. A single water electrolysis cell and two six-cell modules of 1.0 sq ft active electrode area were designed and fabricated. The two six-cell 1.0 sq ft modules incorporate 1.0 sq ft utilized cores, which allow for minimization of module assembly complexity and increased tolerance to pressure differential. A water electrolysis subsystem was designed and fabricated to allow testing of the six-cell modules. After completing checkout, shakedown, design verification and parametric testing, a module was incorporated into the Regenerative Fuel Cell System Breadboard (RFCSB) for testing at Life Systems, Inc., and at NASA JSC.

  16. Endurance test and evaluation of alkaline water electrolysis cells

    NASA Technical Reports Server (NTRS)

    Burke, K. A.; Schubert, F. H.

    1981-01-01

    Utilization in the development of multi-kW low orbit power systems is discussed. The following technological developments of alkaline water electrolysis cells for space power application were demonstrated: (1) four 92.9 cm2 single water electrolysis cells, two using LST's advanced anodes and two using LST's super anodes; (2) four single cell endurance test stands for life testing of alkaline water electrolyte cells; (3) the solid performance of the advanced electrode and 355 K; (4) the breakthrough performance of the super electrode; (5) the four single cells for over 5,000 hours each significant cell deterioration or cell failure. It is concluded that the static feed water electrolysis concept is reliable and due to the inherent simplicity of the passive water feed mechanism coupled with the use of alkaline electrolyte has greater potential for regenerative fuel cell system applications than alternative electrolyzers. A rise in cell voltage occur after 2,000-3,000 hours which was attributed to deflection of the polysulfone end plates due to creepage of the thermoplastic. More end plate support was added, and the performance of the cells was restored to the initial performance level.

  17. Endurance test and evaluation of alkaline water electrolysis cells

    NASA Astrophysics Data System (ADS)

    Burke, K. A.; Schubert, F. H.

    1981-11-01

    Utilization in the development of multi-kW low orbit power systems is discussed. The following technological developments of alkaline water electrolysis cells for space power application were demonstrated: (1) four 92.9 cm2 single water electrolysis cells, two using LST's advanced anodes and two using LST's super anodes; (2) four single cell endurance test stands for life testing of alkaline water electrolyte cells; (3) the solid performance of the advanced electrode and 355 K; (4) the breakthrough performance of the super electrode; (5) the four single cells for over 5,000 hours each significant cell deterioration or cell failure. It is concluded that the static feed water electrolysis concept is reliable and due to the inherent simplicity of the passive water feed mechanism coupled with the use of alkaline electrolyte has greater potential for regenerative fuel cell system applications than alternative electrolyzers. A rise in cell voltage occur after 2,000-3,000 hours which was attributed to deflection of the polysulfone end plates due to creepage of the thermoplastic. More end plate support was added, and the performance of the cells was restored to the initial performance level.

  18. Recovery of Hip and Back Muscle Fatigue Following a Back Extension Endurance Test

    PubMed Central

    WANG-PRICE, SHARON; ALMADAN, MOHAMMAD; STODDARD, CARISSA; MOORE, DUSTIN

    2017-01-01

    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

  19. Isokinetic Strength and Endurance Tests used Pre- and Post-Spaceflight: Test-Retest Reliability

    NASA Technical Reports Server (NTRS)

    Laughlin, Mitzi S.; Lee, Stuart M. C.; Loehr, James A.; Amonette, William E.

    2009-01-01

    To assess changes in muscular strength and endurance after microgravity exposure, NASA measures isokinetic strength and endurance across multiple sessions before and after long-duration space flight. Accurate interpretation of pre- and post-flight measures depends upon the reliability of each measure. The purpose of this study was to evaluate the test-retest reliability of the NASA International Space Station (ISS) isokinetic protocol. Twenty-four healthy subjects (12 M/12 F, 32.0 +/- 5.6 years) volunteered to participate. Isokinetic knee, ankle, and trunk flexion and extension strength as well as endurance of the knee flexors and extensors were measured using a Cybex NORM isokinetic dynamometer. The first weekly session was considered a familiarization session. Data were collected and analyzed for weeks 2-4. Repeated measures analysis of variance (alpha=0.05) was used to identify weekly differences in isokinetic measures. Test-retest reliability was evaluated by intraclass correlation coefficients (ICC) (3,1). No significant differences were found between weeks in any of the strength measures and the reliability of the strength measures were all considered excellent (ICC greater than 0.9), except for concentric ankle dorsi-flexion (ICC=0.67). Although a significant difference was noted in weekly endurance measures of knee extension (p less than 0.01), the reliability of endurance measure by week were considered excellent for knee flexion (ICC=0.97) and knee extension (ICC=0.96). Except for concentric ankle dorsi-flexion, the isokinetic strength and endurance measures are highly reliable when following the NASA ISS protocol. This protocol should allow accurate interpretation isokinetic data even with a small number of crew members.

  20. THE RELATIONSHIP BETWEEN TRUNK ENDURANCE PLANK TESTS AND ATHLETIC PERFORMANCE TESTS IN ADOLESCENT SOCCER PLAYERS

    PubMed Central

    Kaneoka, Koji

    2016-01-01

    Background Although it is believed that trunk function is important for athletic performance, few researchers have demonstrated a significant relationship between the trunk function and athletic performance. Recently, the prone plank and side plank tests have been used to assess trunk function. Purpose The purpose of this study was to investigate the relationships between trunk endurance plank tests and athletic performance tests, including whether there is a relationship between long distance running and trunk endurance plank tests in adolescent male soccer players. Study design Cross sectional study design. Methods Fifty-five adolescent male soccer players performed prone and side plank tests and seven performance tests: the Cooper test, the Yo-Yo intermittent recovery test, the step 50 agility test, a 30-m sprint test, a vertical countermovement jump, a standing five-step jump, and a rebound jump. The relationships between each individual plank test, the combined score of both plank tests, and performance tests were analyzed using the Pearson correlation coefficient. Results The combined score of plank tests was highly correlated with the Yo-Yo intermittent recovery test (r = 0.710, p < 0.001), and was moderately correlated with the Cooper test (r = 0.567, p < 0.001). Poor correlation was observed between the prone plank test and step 50 agility test (r = -0.436, p = 0.001) and no significant correlations were observed between plank tests and jump performance tests. Conclusions The results suggest that trunk endurance plank tests are positively correlated with the Yo-Yo intermittent recovery test, the Cooper test, and the step 50 agility test. Level of Evidence Level 2 PMID:27757284

  1. A Submaximal Running Test With Postexercise Cardiac Autonomic and Neuromuscular Function in Monitoring Endurance Training Adaptation.

    PubMed

    Vesterinen, Ville; Nummela, Ari; Laine, Tanja; Hynynen, Esa; Mikkola, Jussi; Häkkinen, Keijo

    2017-01-01

    Vesterinen, V, Nummela, A, Laine, T, Hynynen, E, Mikkola, J, and Häkkinen, K. A submaximal running test with postexercise cardiac autonomic and neuromuscular function in monitoring endurance training adaptation. J Strength Cond Res 31(1): 233-243, 2017-The aim of this study was to investigate whether a submaximal running test (SRT) with postexercise heart rate recovery (HRR), heart rate variability (HRV), and countermovement jump (CMJ) measurements could be used to monitor endurance training adaptation. Thirty-five endurance-trained men and women completed an 18-week endurance training. Maximal endurance performance and maximal oxygen uptake were measured every 8 weeks. In addition, SRTs with postexercise HRR, HRV, and CMJ measurements were carried out every 4 weeks. Submaximal running test consisted of two 6-minute stages at 70 and 80% of maximum heart rate (HRmax) and a 3-minute stage at 90% HRmax, followed by a 2-minute recovery stage for measuring postexercise HRR, HRV, and CMJ test. The highest responders according to the change of maximal endurance performance showed a significant improvement in running speeds during stages 2 and 3 in SRT, whereas no changes were observed in the lowest responders. The strongest correlation was found between the change of maximal endurance performance and running speed during stage 3, whereas no significant relationships were found between the change of maximal endurance performance and the changes of postexercise HRR, HRV, and CMJ. Running speed at 90% HRmax intensity was the most sensitive variable to monitor adaptation to endurance training. The present submaximal test showed potential to monitor endurance training adaptation. Furthermore, it may serve as a practical tool for athletes and coaches to evaluate weekly the effectiveness of training program without interfering in the normal training habits.

  2. Field endurance test of diesel engines fueled with sunflower oil/diesel fuel blends

    SciTech Connect

    German, T.J.; Kaufman, K.R.; Pratt, G.L.; Derry, J.

    1985-01-01

    Four John Deere and two J.I. Case tractors were fueled with 25% or 50% blends of alkali-refined, winterized sunflower oil and No. 2 diesel fuel while in farm service. All engines were turbocharged, direct injection diesel engines and each was operated for approximately 1000 hours. No power losses were detected during the test period. However, one engine experienced camshaft/valve train failure while in service. Engine deposits were measured according to the CRC Diesel Engine Rating system after the test period was completed. Statistical analysis revealed heavier deposits in most areas of the combustion chamber of the three engines fueled with the 50% sunflower oil/50% No. 2 diesel fuel blend. No detrimental engine deposits due to differences in engine size were observed. No injector coking problems or ring sticking problems were encountered. Bearing wear was normal.

  3. Equivalence Reliability among the FITNESSGRAM[R] Upper-Body Tests of Muscular Strength and Endurance

    ERIC Educational Resources Information Center

    Sherman, Todd; Barfield, J. P.

    2006-01-01

    This study was designed to investigate the equivalence reliability between the suggested FITNESSGRAM[R] muscular strength and endurance test, the 90[degrees] push-up (PSU), and alternate FITNESSGRAM[R] tests of upper-body strength and endurance (i.e., modified pull-up [MPU], flexed-arm hang [FAH], and pull-up [PU]). Children (N = 383) in Grades 3…

  4. Test-retest reliability of lower limb isokinetic endurance in COPD: A comparison of angular velocities

    PubMed Central

    Ribeiro, Fernanda; Lépine, Pierre-Alexis; Garceau-Bolduc, Corine; Coats, Valérie; Allard, Étienne; Maltais, François; Saey, Didier

    2015-01-01

    Background The purpose of this study was to determine and compare the test-retest reliability of quadriceps isokinetic endurance testing at two knee angular velocities in patients with chronic obstructive pulmonary disease (COPD). Methods After one familiarization session, 14 patients with moderate to severe COPD (mean age 65±4 years; forced expiratory volume in 1 second (FEV1) 55%±18% predicted) performed two quadriceps isokinetic endurance tests on two separate occasions within a 5–7-day interval. Quadriceps isokinetic endurance tests consisted of 30 maximal knee extensions at angular velocities of 90° and 180° per second, performed in random order. Test-retest reliability was assessed for peak torque, muscle endurance, work slope, work fatigue index, and changes in FEV1 for dyspnea and leg fatigue from rest to the end of the test. The intraclass correlation coefficient, minimal detectable change, and limits of agreement were calculated. Results High test-retest reliability was identified for peak torque and muscle total work at both velocities. Work fatigue index was considered reliable at 90° per second but not at 180° per second. A lower reliability was identified for dyspnea and leg fatigue scores at both angular velocities. Conclusion Despite a limited sample size, our findings support the use of a 30-maximal repetition isokinetic muscle testing procedure at angular velocities of 90° and 180° per second in patients with moderate to severe COPD. Endurance measurement (total isokinetic work) at 90° per second was highly reliable, with a minimal detectable change at the 95% confidence level of 10%. Peak torque and fatigue index could also be assessed reliably at 90° per second. Evaluation of dyspnea and leg fatigue using the modified Borg scale of perceived exertion was poorly reliable and its clinical usefulness is questionable. These results should be useful in the design and interpretation of future interventions aimed at improving muscle

  5. Reproducibility of an aerobic endurance test for nonexpert swimmers

    PubMed Central

    Veronese da Costa, Adalberto; Costa, Manoel da Cunha; Carlos, Daniel Medeiros; Guerra, Luis Marcos de Medeiros; Silva, Antônio José; Barbosa, Tiago Manoel Cabral dos Santos

    2012-01-01

    Background: This study aimed to verify the reproduction of an aerobic test to determine nonexpert swimmers’ resistance. Methods: The sample consisted of 24 male swimmers (age: 22.79 ± 3.90 years; weight: 74.72 ± 11.44 kg; height: 172.58 ± 4.99 cm; and fat percentage: 15.19% ± 3.21%), who swim for 1 hour three times a week. A new instrument was used in this study (a Progressive Swim Test): the swimmer wore an underwater MP3 player and increased their swimming speed on hearing a beep after every 25 meters. Each swimmer’s heart rate was recorded before the test (BHR) and again after the test (AHR). The rate of perceived exertion (RPE) and the number of laps performed (NLP) were also recorded. The sample size was estimated using G*Power software (v 3.0.10; Franz Faul, Kiel University, Kiel, Germany). The descriptive values were expressed as mean and standard deviation. After confirming the normality of the data using both the Shapiro–Wilk and Levene tests, a paired t-test was performed to compare the data. The Pearson’s linear correlation (r) and intraclass coefficient correlation (ICC) tests were used to determine relative reproducibility. The standard error of measurement (SEM) and the coefficient of variation (CV) were used to determine absolute reproducibility. The limits of agreement and the bias of the absolute and relative values between days were determined by Bland–Altman plots. All values had a significance level of P < 0.05. Results: There were significant differences in AHR (P = 0.03) and NLP (P = 0.01) between the 2 days of testing. The obtained values were r > 0.50 and ICC > 0.66. The SEM had a variation of ±2% and the CV was <10%. Most cases were within the upper and lower limits of Bland–Altman plots, suggesting correlation of the results. The applicability of NLP showed greater robustness (r and ICC > 0.90; SEM < 1%; CV < 3%), indicating that the other variables can be used to predict incremental changes in the physiological condition

  6. Preliminary endurance tests of water vaporizers for resistojet applications

    NASA Technical Reports Server (NTRS)

    Morren, W. Earl; Macrae, Gregory S.

    1993-01-01

    Three water vaporizers designed for resistojet applications were built and tested for periods up to 500 h and 250 thermal cycles. Two of the vaporizers were not sensitive to orientation with respect to gravity, an indication of likely compatibility with low-gravity environments. Some temperatures and pressures in the third were impacted by orientation, although operation was always stable. The pressure drop across the sand-filled version increased by 147 percent in 38 h and 19 thermal cycles. Bonding of the sand granules in the downstream end of the heat exchanger was the suspected cause of failure of this vaporizer. Pressure drops across the two sintered stainless steel-filled versions were more gradual. One, with a pore size of 60 microns, showed an 80 percent increase in 500 h and 250 thermal cycles and another, with a 10 microns poresize, showed a 29 percent increase in 350 h and 175 thermal cycles. Testing of the latter metal-filled vaporizer was ongoing as of this writing. Oxidation of the porous metal packing materials in these vaporizers, with subsequent deposition of oxide particles within the pores, was believed to have caused the observed increases in pressure drops.

  7. Validity of critical frequency test for measuring table tennis aerobic endurance through specific protocol

    PubMed Central

    Zagatto, Alessandro M.; Papoti, Marcelo; Gobatto, Claudio A.

    2008-01-01

    The aim of this study was to validate critical frequency specific test (critf) for the estimation of the aerobic endurance in table tennis players. Methods: Eight male international-level table tennis players participated of this study. Specific tests were applied by using a mechanical ball thrower to control the intensity of the exercise. The critf was determined by applying three or four series of exercises to exhaustion (Tlim). The critf was evaluated by using lactate steady state test (90, 100, and 106 % of critf intensity). The other specific test was an incremental protocol used to determine the anaerobic threshold (AnTBI) and the onset of blood lactate accumulation (OBLA) using a ball thrower. Results: The critf (39.87 ± 3.31 balls·min-1) was not significantly different among AnTBI (48.11 ± 7.36 balls·min- 1) and OBLA3.5 (49.36 ± 12.04 balls·min-1) frequencies and it was correlated with AnTBI parameter (r = 0.78). At frequencies of the 90 and 100% of critf a dynamic equilibrium was verified in lactate concentration between the eighth and twentieth minutes. However, this dynamic equilibrium was not found at 106% intensity. Conclusion: The data indicate that in table tennis the critf model can be used for measuring the aerobic endurance. Key pointsIn table tennis is need the use of a specific protocol for evaluation of the aerobic endurance.The critical frequency test in table tennis seems to represent the intensity of maximal equilibrium of lactatemia.The critical frequency test can be used for measuring table tennis aerobic endurance through specific protocol. PMID:24149951

  8. Associations of maximal strength and muscular endurance test scores with cardiorespiratory fitness and body composition.

    PubMed

    Vaara, Jani P; Kyröläinen, Heikki; Niemi, Jaakko; Ohrankämmen, Olli; Häkkinen, Arja; Kocay, Sheila; Häkkinen, Keijo

    2012-08-01

    The purpose of the present study was to assess the relationships between maximal strength and muscular endurance test scores additionally to previously widely studied measures of body composition and maximal aerobic capacity. 846 young men (25.5 ± 5.0 yrs) participated in the study. Maximal strength was measured using isometric bench press, leg extension and grip strength. Muscular endurance tests consisted of push-ups, sit-ups and repeated squats. An indirect graded cycle ergometer test was used to estimate maximal aerobic capacity (V(O2)max). Body composition was determined with bioelectrical impedance. Moreover, waist circumference (WC) and height were measured and body mass index (BMI) calculated. Maximal bench press was positively correlated with push-ups (r = 0.61, p < 0.001), grip strength (r = 0.34, p < 0.001) and sit-ups (r = 0.37, p < 0.001) while maximal leg extension force revealed only a weak positive correlation with repeated squats (r = 0.23, p < 0.001). However, moderate correlation between repeated squats and V(O2)max was found (r = 0.55, p < 0.001) In addition, BM and body fat correlated negatively with muscular endurance (r = -0.25 - -0.47, p < 0.001), while FFM and maximal isometric strength correlated positively (r = 0.36-0.44, p < 0.001). In conclusion, muscular endurance test scores were related to maximal aerobic capacity and body fat content, while fat free mass was associated with maximal strength test scores and thus is a major determinant for maximal strength. A contributive role of maximal strength to muscular endurance tests could be identified for the upper, but not the lower extremities. These findings suggest that push-up test is not only indicative of body fat content and maximal aerobic capacity but also maximal strength of upper body, whereas repeated squat test is mainly indicative of body fat content and maximal aerobic capacity, but not maximal strength of lower extremities.

  9. Intensity profile during an ultra-endurance triathlon in relation to testing and performance.

    PubMed

    Barrero, A; Chaverri, D; Erola, P; Iglesias, X; Rodríguez, F A

    2014-12-01

    We examined the heart rate (HR)-based intensity profile during an ultra-endurance triathlon (UET) estimated from the individual HR-oxygen uptake (˙VO2) relationship during specific graded tests, relating it to race performance. 9 male ultra-endurance triathletes completed the study. Before racing, subjects performed graded exercise tests involving cycle (C) ergometry, treadmill running (R) and free swimming (S) for peak ˙VO2 and HR at ventilatory thresholds (VT). Exercise-specific HR-˙VO2 regression equations were developed. Mean race HR was higher during S (149.2 (10.1) bpm) than during C (137.1 (5.7) bpm) and R (136.2 (10.5) bpm). During C and R, HR was below both VT (11% and 27-28%). HR differences between S and C correlated with C, R and final times. The greatest differences between S and C were related to the worst times in the next stages. These ultra-endurance triathletes performed S at a higher relative intensity, which was inversely correlated with performance in the following stages. The best predictors of final racing time (81%) were weight-adjusted ˙VO2max and HR difference between C and S. A more adequate characterization of the time pattern during the whole race, especially during S, adds new information concerning the intensity profile and cardiovascular demands of an UET race.

  10. Effects of Age, Exercise Duration, and Test Conditions on Heart Rate Variability in Young Endurance Horses.

    PubMed

    Younes, Mohamed; Robert, Céline; Barrey, Eric; Cottin, François

    2016-01-01

    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

  11. Effects of Age, Exercise Duration, and Test Conditions on Heart Rate Variability in Young Endurance Horses

    PubMed Central

    Younes, Mohamed; Robert, Céline; Barrey, Eric; Cottin, François

    2016-01-01

    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

  12. Ammonia arcjet engine behavior in a cyclic endurance test at 10 kW

    NASA Technical Reports Server (NTRS)

    Polk, J. E.; Goodfellow, K. D.; Pless, L. C.

    1992-01-01

    The behavior of a 30 kWe-class ammonia arcjet operated at 10 kWe during the 707 successful cycles of an endurance test is described. The propellant flow rate was 0.170 g/s, and the measured performance was about 630 s specific impulse at an efficiency of 0.34. Data obtained indicate that the terminal voltage increased over the first 300 cycles, and then remained approximately constant for the remainder of the test, which suggests that the cathode eroded initially and then reached a stable geometry. No major changes were observed in thruster performance. The test was terminated by a series of external arcs.

  13. Comparison of Level and Graded Treadmill Tests to Evaluate Endurance Mountain Runners.

    PubMed

    Balducci, Pascal; Clémençon, Michel; Morel, Baptiste; Quiniou, Géraud; Saboul, Damien; Hautier, Christophe A

    2016-06-01

    Mountain endurance running has increased in popularity in recent years. Thus the aim of the present study was to determine if maximal oxygen uptake (VO2max) and energy cost of running (Cr) measured during level and uphill running are associated. Ten high level male endurance mountain runners performed three maximal oxygen uptake tests at three slope conditions (0, 12.5 and 25%). Metabolic data, step frequency (SF) and step length (SL) were recorded. No significant differences were found in VO2max (63.29 (±3.84), 63.97 (±3.54) and 63.70 (±3.58) mlO2/kg(-1)/min(-1)) or associated metabolic data at 0, 12.5 and 25% slope respectively. High intra-individual correlations were found between metabolic data measured in the three conditions. The energy cost of running was significantly different between slopes (0.192 (±0.01), 0.350 (±0.029) and 0.516 (±0.035) mlO2/kg(-1)/min(-1), p < 0.01), 0, 12.5 and 25% respectively. However, Cr0% was not correlated with either Cr25% or Cr12.5% (rs = 0.09 and rs = 0.10), in contrast, Cr25% and Cr12.5% were correlated (rs = 0.78). Step length was positively correlated with speed under the three slope conditions. Step frequency was significantly lower at 25 compared to 12.5 and 0% slope. We found that the maximum aerobic power did not differ between level and graded treadmill tests. However, the increase in Cr on the inclined versus level conditions varied between subjects. None of the measured anthropometric or kinematic variables could explain the higher increase in Cr of some subjects when running uphill. Thus, a short graded (5min at 12.5%) running test should be performed at a submaximal velocity (around 40% of level vVO2max) to enhance understanding of an endurance runner's uphill capability. Key pointsIn elite endurance mountain runners, there is no difference in VO2max values between level and uphill running.In a homogeneous group of mountain runners, uphill Cr is not associated with level Cr.To assess performance potential of

  14. Comparison of Level and Graded Treadmill Tests to Evaluate Endurance Mountain Runners

    PubMed Central

    Balducci, Pascal; Clémençon, Michel; Morel, Baptiste; Quiniou, Géraud; Saboul, Damien; Hautier, Christophe A.

    2016-01-01

    Mountain endurance running has increased in popularity in recent years. Thus the aim of the present study was to determine if maximal oxygen uptake (VO2max) and energy cost of running (Cr) measured during level and uphill running are associated. Ten high level male endurance mountain runners performed three maximal oxygen uptake tests at three slope conditions (0, 12.5 and 25%). Metabolic data, step frequency (SF) and step length (SL) were recorded. No significant differences were found in VO2max (63.29 (±3.84), 63.97 (±3.54) and 63.70 (±3.58) mlO2/kg-1/min-1) or associated metabolic data at 0, 12.5 and 25% slope respectively. High intra-individual correlations were found between metabolic data measured in the three conditions. The energy cost of running was significantly different between slopes (0.192 (±0.01), 0.350 (±0.029) and 0.516 (±0.035) mlO2/kg-1/min-1, p < 0.01), 0, 12.5 and 25% respectively. However, Cr0% was not correlated with either Cr25% or Cr12.5% (rs = 0.09 and rs = 0.10), in contrast, Cr25% and Cr12.5% were correlated (rs = 0.78). Step length was positively correlated with speed under the three slope conditions. Step frequency was significantly lower at 25 compared to 12.5 and 0% slope. We found that the maximum aerobic power did not differ between level and graded treadmill tests. However, the increase in Cr on the inclined versus level conditions varied between subjects. None of the measured anthropometric or kinematic variables could explain the higher increase in Cr of some subjects when running uphill. Thus, a short graded (5min at 12.5%) running test should be performed at a submaximal velocity (around 40% of level vVO2max) to enhance understanding of an endurance runner’s uphill capability. Key points In elite endurance mountain runners, there is no difference in VO2max values between level and uphill running. In a homogeneous group of mountain runners, uphill Cr is not associated with level Cr. To assess performance potential of

  15. Verification Testing to Confirm VO2max in Altitude-Residing, Endurance-Trained Runners.

    PubMed

    Weatherwax, R M; Richardson, T B; Beltz, N M; Nolan, P B; Dalleck, L

    2016-06-01

    We sought to explore the utility of the verification trial to confirm individual attainment of 'true' VO2max in altitude-residing, endurance-trained runners during treadmill exercise. 24 elite endurance-trained men and women runners (age=21.5±3.3 yr, ht=174.8±9.3 cm, body mass=60.5±6.7 kg, PR 800 m 127.5±13.1 s) completed a graded exercise test (GXT) trial (VO2max=60.0±5.8 mL·kg(-1)·min(-1)), and returned 20 min after incremental exercise to complete a verification trial (VO2max=59.6±5.7 mL·kg(-1)·min(-1)) of constant load, supramaximal exercise. The incidence of 'true' VO2max confirmation using the verification trial was 24/24 (100%) with all participants revealing differences in VO2max≤3% (the technical error of our equipment) between the GXT and verification trials. These findings support use of the verification trial to confirm VO2max attainment in altitude-residing, endurance-trained runners.

  16. Endurance testing of downstream cathodes on a low-power MPD thruster

    NASA Technical Reports Server (NTRS)

    Burkhart, J. A.; Rose, J. R.

    1974-01-01

    A low-power MPD thruster with downstream cathode was tested for endurance with a series of hollow cathode designs. Failure modes and failure mechanisms were identified. A new hollow cathode (with rod inserts) has emerged which shows promise for long life. The downstream positioning of the cathode was also changed from an on-axis location to an off-axis location. Data are presented for a 1332-hour life test of this new hollow cathode located at the new off-axis location. Xenon propellant was used.

  17. Muscle Strength Endurance Testing Development Based Photo Transistor with Motion Sensor Ultrasonic

    NASA Astrophysics Data System (ADS)

    Rusdiana, A.

    2017-03-01

    The endurance of upper-body muscles is one of the most important physical fitness components. As technology develops, the process of test and assessment is now getting digital; for instance, there are a sensor stuck to the shoe (Foot Pod, Polar, and Sunto), Global Positioning System (GPS) and Differential Global Positioning System (DGPS), radar, photo finish, kinematic analysis, and photocells. Those devices aim to analyze the performances and fitness of athletes particularly the endurance of arm, chest, and shoulder muscles. In relation to that, this study attempt to create a software and a hardware for pull-ups through phototransistor with ultrasonic motion sensor. Components needed to develop this device consist of microcontroller MCS-51, photo transistor, light emitting diode, buzzer, ultrasonic sensor, and infrared sensor. The infrared sensor is put under the buffer while the ultrasonic sensor is stuck on the upper pole. The components are integrated with an LED or a laptop made using Visual Basic 12 software. The results show that pull-ups test using digital device (mean; 9.4 rep) is lower than using manual calculation (mean; 11.3 rep). This is due to the fact that digital test requires the test-takers to do pull-ups perfectly.

  18. Real-time and accelerated outdoor endurance testing of solar cells

    NASA Technical Reports Server (NTRS)

    Forestieri, A. F.; Anagnostou, E.

    1977-01-01

    Real-time and accelerated outdoor endurance testing was performed on a variety of samples of interest to the National Photovoltaic Conversion Program. The real-time tests were performed at seven different sites and the accelerated tests were performed at one of those sites in the southwestern United States. The purpose of the tests were to help evaluate the lifetime of photovoltaic systems. Three types of samples were tested; transmission samples of possible cover materials, sub-modules constructed using these materials attached to solar cells, and solar cell modules produced by the manufacturers for the ERDA program. Results indicate that suitable cover materials are glass, FEP-A and PFA. Dirt accumulation and cleanability are important factors in the selection of solar cell module covers and encapsulants.

  19. Laser Cut Nitinol Tubing Fatigue Coupon: Design, Testing, and Endurance Limit

    NASA Astrophysics Data System (ADS)

    Forcucci, Stephen J.

    2014-07-01

    Nitinol medical device implants made from a laser cut tubing process (i.e., stents, valve structures, etc.) frequently require a fatigue durability assessment, which necessitates determining the material fatigue properties. Towards the goal of determining the strain-based endurance limit of medical grade superelastic Nitinol tubing, a coupon was designed and evaluated via FEA using Abaqus software, produced via laser cutting, shape setting, and electro-polishing processes, and then fatigue tested to 10 million cycles. FEA was used to determine the strain versus alternating displacement amplitude for the coupon. Error due to dimensional tolerances was determined. The coupons were then fatigue tested in a 37 °C temperature deionized water bath at alternating strain levels ranging from 0.75 to 4.0% at zero mean strain. Sample replication was greater than 90%, and the median alternating strain fatigue limit was determined via two methods. Confidence and reliability with maximum likelihood statistics are used to present a strain-based endurance limit for the material. The results seem to differ from previous published values.

  20. Comparison of incremental and constant load tests of inspiratory muscle endurance in COPD.

    PubMed

    Hill, K; Jenkins, S C; Philippe, D L; Shepherd, K L; Hillman, D R; Eastwood, P R

    2007-09-01

    The aim of the present study was to determine the relative value of incremental and constant load tests in detecting changes in inspiratory muscle endurance following high-intensity inspiratory muscle training (H-IMT) in chronic obstructive pulmonary disease. In total, 16 subjects (11 males; forced expiratory volume in one second (FEV(1)) 37.4+/-12.5%) underwent H-IMT. In addition, 17 subjects (11 males; FEV(1) 36.5+/-11.5%) underwent sham inspiratory muscle training (S-IMT). Training took place three times a week for 8 weeks. Baseline and post-training measurements were obtained of maximum threshold pressure sustained during an incremental load test (P(th,max)) and time breathing against a constant load (t(lim)). Breathing pattern was unconstrained. H-IMT increased P(th,max) and t(lim) relative to baseline and to any change seen following S-IMT. The effect size for P(th,max) was greater than for t(lim). Post-training tests were accompanied by changes in breathing pattern, including decreased duty cycle, which may have served to decrease inspiratory work and thereby contribute to the increase in P(th,max) and t(lim) in both groups. When assessing inspiratory muscle function in chronic obstructive pulmonary disease via tests in which the pattern of breathing is unconstrained, the current authors recommend incremental load tests be used in preference to constant load tests. However, to attribute changes in these tests to improvements in inspiratory muscle endurance, breathing pattern should be controlled.

  1. Dynamometer Elbow Strength and Endurance Testing After Distal Biceps Reconstruction w/Allograft

    PubMed Central

    McGee, Alan; Strauss, Eric Jason; Jazrawi, Laith M.

    2015-01-01

    Objectives: The purpose of the current study is to investigate the functional strength outcomes of late distal biceps reconstruction using allograft tissue. Methods: Patients who underwent distal biceps reconstruction with allograft tissue between May 2007 and May 2013 were identified. Charts were retrospectively reviewed for post-operative complications, gross flexion and supination strength, and range of motion (ROM). Isokinetic strength and endurance in elbow flexion and forearm supination were measured in both arms. Tests were conducted using a dynamometer at 60o per second for isokinetic strength and 240o per second for endurance. Isometric strength testing was also measured for elbow flexion and forearm supination. Paired t tests were used for statistical analysis. Results: Ten patients with a mean age of 48 years (range 42 - 61 years) were included in the study. Distal biceps reconstruction was performed using an Achilles tendon allograft in 9 patients and a combination of tibialis anterior allograft and gracilis allograft in 1 patient. Of the reconstructions, 50% involved the dominant arm. Full ROM was observed in all patients at the time of their final follow up assessment. The mean follow-up for dynamometer strength testing was 34 months (range 13-81 months). No statistical differences were noted between data obtained from operative and contralateral extremities. The average peak torque of the operative limb (38.5± 5.9 Nm) was 91.7% of that of the contralateral limb (41.8±4.9 Nm) in flexion and 93.4% (operative, 5.7±1.3 Nm; contralateral, 6.1± 1.0 Nm) in supination. No significant differences were found in fatigue index between operative or contralateral limbs for flexion (operative, 34.1±17.1%; contralateral, 30.8±17.1%; p = 0.29) or supination (operative, 38.2±16.5%; contralateral, 42.1±11.9%; p = 0.65). . The only complication observed was a transient PIN palsy in one patient which resolved by 3 months post-operatively. All patients reported

  2. Methods of testing for endurance of structural elements using simulated acoustic loading

    NASA Astrophysics Data System (ADS)

    1993-10-01

    ESDU 93027 discusses methods of testing structural elements, designed to represent features of the full-size structure, using random-amplitude narrowband loading to simulate response to acoustic loading. A wide range of element geometries is included with information on probable failure locations, typical sizes, and any inherent limitations. Mounting methods are considered with examples of multiple specimen tests to allow the scatter in fatigue life to be determined in minimum elapsed time. Guidance is provided on excitation requirements, the measurement and monitoring instrumentation, specimen tuning, and the assessment of structural damping and response linearity. The means of defining a failure are considered, with particular reference to composite structures, and the use of residual strength assessment is discussed. The application of the techniques to obtain endurance data at elevated temperature is addressed. Finally, guidance is included on the interpretation of the results.

  3. Subclinical diseases underlying poor performance in endurance horses: diagnostic methods and predictive tests.

    PubMed

    Fraipont, A; Van Erck, E; Ramery, E; Richard, E; Denoix, J-M; Lekeux, P; Art, T

    2011-08-06

    Thirty-eight endurance horses underwent clinical and ancillary examinations, including haematological and biochemical evaluation, standardised exercise tests both on a treadmill and in the field, Doppler echocardiography, impulse oscillometry, video endoscopy and collection of respiratory fluids. All of the examined poorly performing horses were affected by subclinical diseases, and most of them had multiple concomitant disorders. On the contrary, the well-performing horses were free of any subclinical disease. The most frequently diagnosed diseases were respiratory disorders, followed by musculoskeletal and cardiac problems. Poor performers exhibited lower speeds at blood lactate concentration of 4 mmol/l (VLA4) and at heart rates of 160 (V160) and 200 bpm (V200) on the treadmill and in the field, as well as slower recovery of heart rate.

  4. Endurance tests of valves with cobalt-free hardfacing alloys: PWR phase

    SciTech Connect

    Murphy, E.V.; Inglis, I. )

    1992-05-01

    Atomic Energy of Canada Limited (AECL) is conducting endurance tests on valves hard-faced with four cobalt-free alloys. The first phase of the program, in which PWR primary heat transport conditions were simulated in AECL's valve test loop, has been completed. The candidate alloys are NOREM 01, NOREM 04, EB 5183 and EVERIT 50. One valve with Stellite 6 trim served as the standard. Prior to loop testing, a baseline inaugural inspection was performed. During testing the loop was shutdown at approximately 500 cycle intervals, and the valves were disassembled for examination. The examinations included seat leak tests, profilometry, nondestructive inspection and finally destructive examination. Corrosion coupons in the loop were used to monitor any material loss due solely to corrosion mechanisms. This report summarizes the final examination results and discusses the relative performance of the candidate alloys. The results indicate that, based upon the sliding wear damage assessment and seat leakage test results, all the candidate alloys perform better than the Stellite 6 control sample. On the same basis, NOREM 04 and EB 5183 are the best of the candidate alloys, although there are only minor differences in performance among the four alloys.

  5. Endurance tests of valves with cobalt-free hardfacing alloys: PWR phase. Final report

    SciTech Connect

    Murphy, E.V.; Inglis, I.

    1992-05-01

    Atomic Energy of Canada Limited (AECL) is conducting endurance tests on valves hard-faced with four cobalt-free alloys. The first phase of the program, in which PWR primary heat transport conditions were simulated in AECL`s valve test loop, has been completed. The candidate alloys are NOREM 01, NOREM 04, EB 5183 and EVERIT 50. One valve with Stellite 6 trim served as the standard. Prior to loop testing, a baseline inaugural inspection was performed. During testing the loop was shutdown at approximately 500 cycle intervals, and the valves were disassembled for examination. The examinations included seat leak tests, profilometry, nondestructive inspection and finally destructive examination. Corrosion coupons in the loop were used to monitor any material loss due solely to corrosion mechanisms. This report summarizes the final examination results and discusses the relative performance of the candidate alloys. The results indicate that, based upon the sliding wear damage assessment and seat leakage test results, all the candidate alloys perform better than the Stellite 6 control sample. On the same basis, NOREM 04 and EB 5183 are the best of the candidate alloys, although there are only minor differences in performance among the four alloys.

  6. The endurance shuttle walk test: an alternative to the six-minute walk test for the assessment of ambulatory oxygen.

    PubMed

    Revill, S M; Noor, M Z; Butcher, G; Ward, M J

    2010-01-01

    UK guidelines for domiciliary oxygen have suggested the six-minute walk test or shuttle walk tests as suitable functional measures for the clinical assessment of ambulatory oxygen (AO). To date, there is limited evidence that would support the use of shuttle walk tests as assessment tools for AO. The endurance shuttle walk test (ESWT) is used increasingly as an assessment tool within pulmonary rehabilitation (PR) but its potential as an investigative test for AO has not been explored. Using the same test for both PR and AO assessment is appealing since it would improve efficiency and act to standardise outcome measures in this patient population. The aim of this study was to examine the responsiveness and repeatability of the ESWT to AO and to compare the response with that of the six-minute walk test (6MWT). Twenty-three patients with chronic obstructive pulmonary disease (COPD) performed, in random order, the ESWT and the 6MWT on air and whilst breathing AO. Oxygen saturation and Borg ratings of breathlessness and perceived exertion were recorded. On a third day, eleven patients repeated the ESWT with AO in order to measure repeatability. There was a significantly greater change in the ESWT with oxygen than the change recorded from the 6MWT (66 [91] vs 6 [28] m respectively; P < .05). When repeated on a separate day, the mean difference (95% CI) between distances walked on the ESWT with AO was 0.91 (-47, 49) m. The ESWT was more responsive than the 6MWT for detecting improvements in walking endurance whilst breathing AO.

  7. Validity of Alternative Fitnessgram Upper Body Tests of Muscular Strength and Endurance among Seventh and Eighth Grade Males and Females

    ERIC Educational Resources Information Center

    Hobayan, Kalani; Patterson, Debra; Sherman, Clay; Wiersma, Lenny

    2014-01-01

    In a society in which obesity levels have tripled in the past 30 years, the importance of increased fitness levels within the academic setting has become even more critical. The purpose of this study was to investigate the validity of alternative Fitnessgram upper body tests of muscular strength and endurance among seventh and eighth grade males…

  8. Determination of normal values for an isocapnic hyperpnea endurance test in healthy individuals.

    PubMed

    Vincent, Marjolaine; Court-Fortune, Isabelle; Brun, Clément; Camdessanché, Jean-Philippe; Vergès, Samuel; Costes, Frédéric

    2016-08-01

    Respiratory Muscle Endurance (RME) is an alternative way to assess respiratory muscle impairment but normal values are lacking to use this test in a clinical perspective. Our objective was then to determine reference values of RME in healthy subjects. We recruited 161 healthy subjects (25-80 years old) who were distributed within 5 groups with a 10-year range. We measured vital capacity (VC) and maximal respiratory pressure (MIP, MEP). The RME test consisted of isocapnic hyperpnea at increasing levels of ventilation until exhaustion to determine Tlim (expressed in minutes and as percentage of maximal voluntary ventilation, MVV). A significant difference between age-groups was observed for both VC and MEP expressed as percentage of predicted value. Mean Tlim was 21.8±5.9min [95% confidence interval 20.9-22.8], 74.4±15.9% of predicted MVV [95% CI 71.8-76.9]. Tlim was similar among age groups. Tolerance to the RME test was excellent. This study provides normal values of RME in a large age range of healthy subjects and demonstrates that RME is preserved in the elderly.

  9. Training status (endurance or sprint) and catecholamine response to the Wingate-test in women.

    PubMed

    Jacob, C; Zouhal, H; Vincent, S; Gratas-Delamarche, A; Berthon, P M; Bentué-Ferrer, D; Delamarche, P

    2002-07-01

    The aim of this study was to verify if, as for men, training status induces different catecholamine responses to exercise. To do this, we investigated the effect of training status (sprint or endurance) on plasma catecholamine response to a supramaximal exercise in women. Nineteen subjects took part in our study: six untrained subjects (UT), seven endurance trained subjects (ET) and six sprint trained ones (ST). The trained subjects (ET and ST) were all competing at a high national level. The maximal power (W max ) and the mean power (W) were determined from the Wingate-test. Blood lactate, adrenaline (A) and noradrenaline (NA) were analysed at rest (La 0, A 0 and NA 0 ), immediately at the end of the exercise (A max and NA max ) and after 5 min recovery (La max [3 min in arterialized blood], A 5 and NA 5 ). The disappearance of A and NA was judged by the ratio (A max -A 5 )/A max and (NA max -NA 5 )/NA 5. The ratio A max /NA max was considered as an index of the adrenal medulla responsiveness to the sympathetic nervous activity. As expected, during the Wingate-test ST exhibited significantly higher performances compared to UT and ET. But in contrast to the men's data no difference was observed between the three groups both for La max (13.1 +/- 0.8 mmol x L (-1); 14.8 +/- 1.0 mmol x L (-1) and 11.2 +/- 0.5 mmol x L (-1) respectively for ET, ST and UT), NA max (22.1 +/- 1.2 nmol x L (-1); 13.1 +/- 2.4 nmol x L (-1) and 20.2 +/- 7 nmol x L (-1)respectively for ET, ST and UT) and A max (4.1 +/- 0.8 nmol x L (-1); 2.6 +/- 0.6 nmol x L (-1); 13.1 +/- 0.6 nmol x L (-1) respectively for ET, ST and UT). Consequently the ratio A max /NA max was similar in UT, ET and ST (respectively 0.2 +/- 0.03; 0.2 +/- 0.04; 0.17 +/- 0.04), These results indicated, in contrast to the men's data, that the catecholamine response to the Wingate-test did not differ between female subjects of different status of training. In conclusion this study did not find any significant effect of training

  10. Comparison of laboratory and "on-court" endurance testing in tennis.

    PubMed

    Smekal, G; Pokan, R; von Duvillard, S P; Baron, R; Tschan, H; Bachl, N

    2000-05-01

    Treadmill testing (TT) commonly used in endurance testing is often not sport-specific. Therefore a field test (FT) for tennis players was developed. The purpose was 1) to compare metabolic and cardiorespiratory response between TT and FT and 2) to assess tennis stroke ratings during FT. In both tests ventilatory variables (VO2, VE, VT, Bf, VE x VO2(-1)), heart rate (HR), and lactate (LA) were measured. For both tests an "individual anaerobic threshold" (IAT) was calculated. The comparison of TT and FT yielded significant differences in cardiorespiratory and metabolic response. LA and VE were significantly higher in TT compared to FT at VO2 of 35, 40, and 45 ml x kg(-1) x min(-1). There were statistical differences between IAT resulting from both tests (TT vs. FT): HR (165+/-16, 175+/-11, p<0.001), VO2 (44.4+/-4.3, 47.8+/-4.8, p<0.05), LA (3.1+/-0.5, 2.5+/-0.4, p < 0.001), VE (97.0+/-15.6, 89.1+/-14.9, p < 0.05), VT (2.66+/-0.34, 2.34+/-0.47, p<0.05), VE/VO2 (27.9+/-3.9, 23.9+/-2.9, p<0.01). High correlation was found between stroke ratings and the national ranking of the players. We concluded that 1) metabolic, ventilatory, and cardiorespiratory demands of TT vs. FT were (semi)sport-specific and significantly different and 2) that the stroke rating in our study was a good predictor for tournament performance (r = 0.94). This type of stroke rating can be implemented in a FT.

  11. Effects of endurance training on reduction of plasma glucose during high intensity constant and incremental speed tests in Wistar rats

    PubMed Central

    Abreu, P.; Vitzel, K.F.; Monteiro, I.C.C.R.; Lima, T.I.; Queiroz, A.N.; Leal-Cardoso, J.H.; Hirabara, S.M.; Ceccatto, V.M.

    2016-01-01

    The aim of this research was to investigate the effects of endurance training on reduction of plasma glucose during high intensity constant and incremental speed tests in Wistar rats. We hypothesized that plasma glucose might be decreased in the exercised group during heavy (more intense) exercise. Twenty-four 10-week-old male Wistar rats were randomly assigned to sedentary and exercised groups. The prescription of endurance exercise training intensity was determined as 60% of the maximum intensity reached at the incremental speed test. The animals were trained by running on a motorized treadmill, five days/week for a total period of 67 weeks. Plasma glucose during the constant speed test in the exercised group at 20 m/min was reduced at the 14th, 21st and 28th min compared to the sedentary group, as well at 25 m/min at the 21st and 28th min. Plasma glucose during the incremental speed test was decreased in the exercised group at the moment of exhaustion (48th min) compared to the sedentary group (27th min). Endurance training positively modulates the mitochondrial activity and capacity of substrate oxidation in muscle and liver. Thus, in contrast to other studies on high load of exercise, the effects of endurance training on the decrease of plasma glucose during constant and incremental speed tests was significantly higher in exercised than in sedentary rats and associated with improved muscle and hepatic oxidative capacity, constituting an important non-pharmacological intervention tool for the prevention of insulin resistance, including type 2 diabetes mellitus. PMID:27783805

  12. Determination of Judo Endurance Performance Using the Uchi - Komi Technique and an Adapted Lactate Minimum Test

    PubMed Central

    Azevedo, Paulo H.S.M.; Drigo, Alexandre J.; Carvalho, Mauro C.G.A.; Oliveira, João C.; Nunes, João E.D.; Baldissera, Vilmar; Perez, Sérgio E.A.

    2007-01-01

    This study aimed to evaluate the viability to use Uchi-komi (UK) in the evaluation of the judo endurance performance and using lactate threshold the analysis of the blood lactate ([Lac]) and heart rate (HR) determined through a lactate minimum test. The subjects were a group of 6 male, volunteer judokas, from 25.17 ± 5.76 years old, weight 84.50 ± 23.78 kg and height 1.78 ± 0.10 m, competitors of different levels of performance (from regional to international competitions) and match experience of (11 ± 6) years old. Three tests were performed: a) 3000 m dash in track, b) the adapted test of lactate minimum for running and c) for UK, with execution of the blow ippon-seoi-nague. No significant difference was evident for the track tests and UK in relation to blood lactate and heart rate (p > 0.05) (3.87 ± 0.38 vs 4.17 ± 0.54 mmol·L-1 and 167 ± 2 vs 152 ± 7 b·min-1, respectively). In conclusion it is stressed that: 1) The specific test for lactate minimum in judo sport is a promising possibility of aerobic capacity evaluation and a instrument of intensity training control; 2) The metabolic profile in Vlm and UKlm is similar, because there are not differences in the [Lac] and in the HR at this intensity; 3) It is possible to estimate the training intensity through the determination of the lactate minimum intensity in running (Vlm) and the Heart Rate associated (HR) from the execution of ippon-seoi- nague (uchi-komi) in judo training; 4) The Vlm for judo athletes is approximately 88% of the V3000. Key points The specific test for lactate minimum in judo sport is a promising possibility of aerobic capacity evaluation; This is a instrument for intensity training control for judo players; The metabolic profile is similar between running and uki-komi (ippon-seoi-nague techniques) at lactate minimum intensity. PMID:24198697

  13. The Medical Symptom Validity Test in the evaluation of Operation Iraqi Freedom/Operation Enduring Freedom soldiers: a preliminary study.

    PubMed

    Whitney, Kriscinda A; Shepard, Polly H; Williams, Amanda L; Davis, Jeremy J; Adams, Kenneth M

    2009-03-01

    The clinical utility of the Medical Symptom Validity Test (MSVT) for soldiers returning from service in Operation Iraqi Freedom or Operation Enduring Freedom was preliminarily investigated through retrospective chart review. Results showed that 17%, or 4 of 23, Operation Iraqi Freedom/Operation Enduring Freedom patients at a Polytrauma Network Site (Level 2), performed below cut-offs on the MSVT. On "easy" subtests of the MSVT, the group of individuals who failed the MSVT performed significantly worse than the group of individuals who passed. However, there were no significant group differences on the "hard" subtests of the MSVT. When the profiles of individuals who failed the MSVT were examined, none of them met the criteria for the Dementia Profile. These preliminary findings and additional test data supported the conclusion that participants who failed the MSVT were exhibiting diminished symptom validity, suggesting that the specificity of the MSVT was 100%.

  14. Ball-Sport Endurance and Sprint Test (BEAST90): validity and reliability of a 90-minute soccer performance test.

    PubMed

    Williams, Jeremy D; Abt, Grant; Kilding, Andrew E

    2010-12-01

    The aim of this study was to determine the validity and reliability of a 90-minute soccer performance test: Ball-sport Endurance and Sprint Test (BEAST90). Fifteen healthy male amateur soccer players participated and attended 5 testing sessions over a 10-day period to perform physiologic and soccer-specific assessments. This included familiarization sessions and 2 full trials of the BEAST90, separated by 7 days. The total 90-minute distance, mean percent peak heart rate (HRpeak), and estimated percent peak oxygen uptake of the BEAST90 were 8,097 ± 458 m, 85 ± 5% and 82 ± 14%, respectively. Measures obtained from trial 1 and trial 2 were not significantly different (p > 0.05). Reliability of measures over 90 minutes ranged from 0.9-25.5% (% typical error). The BEAST90 protocol replicated soccer match play in terms of time, movement patterns, physical demands (volume and intensity), distances, and mean and HRpeak values, as well as having an aerobic load similar to that observed during a soccer match. Reproducibility of key physical measures during the BEAST90 were mostly high, suggesting good reliability. The BEAST90 could be used in studies that wish to determine the effects of training or nutritional interventions on prolonged intermittent physical performance.

  15. Heat-pipe gas-combustion system endurance test for Stirling engine. Final report, May 1990-September 1990

    SciTech Connect

    Mahrle, P.

    1990-12-01

    Stirling Thermal Motors, Inc., (STM) has been developing a general purpose Heat Pipe Gas Combustion System (HPGC) suitable for use with the STM4-120 Stirling engine. The HPGC consists of a parallel plate recuperative preheater, a finned heat pipe evaporator and a film cooled gas combustor. A principal component of the HPGC is the heat pipe evaporator which collects and distributes the liquid sodium over the heat transfer surfaces. The liquid sodium evaporates and flows to the condensers where it delivers its latent heat. The report presents test results of endurance tests run on a Gas-Fired Stirling Engine (GFSE). Tests on a dynamometer test stand yielded 67 hours of engine operation at power levels over 10 kW (13.5 hp) with 26 hours at power levels above 15 kW (20 hp). Total testing of the engine, including both motoring tests and engine operation, yielded 245 hours of engine run time.

  16. Can persistence hunting signal male quality? A test considering digit ratio in endurance athletes.

    PubMed

    Longman, Daniel; Wells, Jonathan C K; Stock, Jay T

    2015-01-01

    Various theories have been posed to explain the fitness payoffs of hunting success among hunter-gatherers. 'Having' theories refer to the acquisition of resources, and include the direct provisioning hypothesis. In contrast, 'getting' theories concern the signalling of male resourcefulness and other desirable traits, such as athleticism and intelligence, via hunting prowess. We investigated the association between androgenisation and endurance running ability as a potential signalling mechanism, whereby running prowess, vital for persistence hunting, might be used as a reliable signal of male reproductive fitness by females. Digit ratio (2D:4D) was used as a proxy for prenatal androgenisation in 439 males and 103 females, while a half marathon race (21km), representing a distance/duration comparable with that of persistence hunting, was used to assess running ability. Digit ratio was significantly and positively correlated with half-marathon time in males (right hand: r = 0.45, p<0.001; left hand: r = 0.42, p<0.001) and females (right hand: r = 0.26, p<0.01; left hand: r = 0.23, p = 0.02). Sex-interaction analysis showed that this correlation was significantly stronger in males than females, suggesting that androgenisation may have experienced stronger selective pressure from endurance running in males. As digit ratio has previously been shown to predict reproductive success, our results are consistent with the hypothesis that endurance running ability may signal reproductive potential in males, through its association with prenatal androgen exposure. However, further work is required to establish whether and how females respond to this signalling for fitness.

  17. Can Persistence Hunting Signal Male Quality? A Test Considering Digit Ratio in Endurance Athletes

    PubMed Central

    Longman, Daniel; Wells, Jonathan C. K.; Stock, Jay T.

    2015-01-01

    Various theories have been posed to explain the fitness payoffs of hunting success among hunter-gatherers. ‘Having’ theories refer to the acquisition of resources, and include the direct provisioning hypothesis. In contrast, ‘getting’ theories concern the signalling of male resourcefulness and other desirable traits, such as athleticism and intelligence, via hunting prowess. We investigated the association between androgenisation and endurance running ability as a potential signalling mechanism, whereby running prowess, vital for persistence hunting, might be used as a reliable signal of male reproductive fitness by females. Digit ratio (2D:4D) was used as a proxy for prenatal androgenisation in 439 males and 103 females, while a half marathon race (21km), representing a distance/duration comparable with that of persistence hunting, was used to assess running ability. Digit ratio was significantly and positively correlated with half-marathon time in males (right hand: r = 0.45, p<0.001; left hand: r = 0.42, p<0.001) and females (right hand: r = 0.26, p<0.01; left hand: r = 0.23, p = 0.02). Sex-interaction analysis showed that this correlation was significantly stronger in males than females, suggesting that androgenisation may have experienced stronger selective pressure from endurance running in males. As digit ratio has previously been shown to predict reproductive success, our results are consistent with the hypothesis that endurance running ability may signal reproductive potential in males, through its association with prenatal androgen exposure. However, further work is required to establish whether and how females respond to this signalling for fitness. PMID:25853679

  18. Endurance testing of first generation (Block 1) commercial solar cell modules

    NASA Technical Reports Server (NTRS)

    Anagnostou, E.; Forestieri, A. F.

    1978-01-01

    To determine lifetimes of the first generation (Block 1) commercial solar cell modules used in solar cell arrays, a program was initiated to expose these modules to a range of environments. The conditions endured by these modules encompassed hot and dry, hot and humid, tropical rain forests, sea-air, urban industrial and urban clean. Exposures were for periods up to 1 year. The effect of outdoor exposure on the performance of the modules was determined using current-voltage curves. Short-circuit current (I sub sc) and maximum power (P sub max) were the parameters monitored. In all cases, there was a loss of performance of the modules with outdoor exposure.

  19. Cardiorespiratory endurance evaluation using heart rate analysis during ski simulator exercise and the Harvard step test in elementary school students.

    PubMed

    Lee, Hyo Taek; Roh, Hyo Lyun; Kim, Yoon Sang

    2016-01-01

    [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.

  20. Cardiorespiratory endurance evaluation using heart rate analysis during ski simulator exercise and the Harvard step test in elementary school students

    PubMed Central

    Lee, Hyo Taek; Roh, Hyo Lyun; Kim, Yoon Sang

    2016-01-01

    [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

  1. A 15,000-hour cyclic endurance test of an 8-centimeter-diameter electron bombardment mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Nakanishi, S.

    1976-01-01

    A laboratory model 8 cm thruster with improvements to minimize ion chamber erosion and peeling of sputtered metal was subjected to a cyclic endurance test for 15,040 hours and 460 restarts. A charted history of several thruster operating variables and off-normal events are shown in 600-hour segments at three points in the test. The transient behavior of these variables during a typical start-stop cycle is presented. Finding of the post-test inspection confirmed most of the expected results. Charge exchange ions caused normal accelerator grid erosion. The workability of the various design features was substantiated, and attainable improvements in propellant utilization efficiency should significantly reduce accelerator erosion.

  2. Performance and endurance testing of a prototype carbon dioxide and humidity control system for Space Shuttle extended mission capability

    NASA Technical Reports Server (NTRS)

    Lin, C. H.; Cusick, R. J.

    1985-01-01

    An advanced flight prototype regenerable CO2 and humidity control system was delivered to NASA-JSC in February 1980. It is pointed out that this system offers substantial weight savings compared with the Shuttle Orbiter expendable lithium hydroxide CO2 removal system for extended duration missions. The present paper provides a brief description of the 4- to 10-man regenerable CO2 and humidity control system. The potential advantages which can be realized for an extended duration Shuttle mission are considered along with the results of extensive testing conducted at JSC. The performance evaluation and endurance tests show that the system is capable of long-term operation (up to 60 days) without maintenance.

  3. Circulorespiratory Endurance.

    ERIC Educational Resources Information Center

    Allsen, Philip E.

    1981-01-01

    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)

  4. The 6-min mastication test: a unique test to assess endurance of continuous chewing, normal values, reliability, reproducibility and usability in patients with mitochondrial disease.

    PubMed

    van den Engel-Hoek, L; Knuijt, S; van Gerven, M H J C; Lagarde, M L J; Groothuis, J T; de Groot, I J M; Janssen, M C H

    2017-03-01

    In patients with mitochondrial disease, fatigue and muscle problems are the most common complaints. They also experience these complaints during mastication. To measure endurance of continuous mastication in patients with mitochondrial diseases, the 6-min mastication test (6MMT) was developed. This study included the collection of normal data for the 6MMT in a healthy population (children and adults). During 6 min of continuous mastication on a chew tube chewing cycles per minute, total amount of chewing cycles and the difference between minute 1 (M1 ) and minute 6 (M2 ) were collected in 271 healthy participants (5-80 years old). These results were compared with those of nine paediatric and 25 adult patients with a mitochondrial disease. Visual analogue scale (VAS) scores were collected directly after the test and after 5 min. A qualitative rating was made on masticatory movements. The reproducibility of the 6MMT in the healthy population with an interval of approximately 2 weeks was good. The inter-rater reliability for the observations was excellent. The patient group demonstrated lower total amount of chewing cycles or had greater differences between M1 and M6 . The 6MMT is a reliable and objective test to assess endurance of continuous chewing. It demonstrates the ability of healthy children and adults to chew during 6 min with a highly stable frequency of mastication movements. The test may give an explanation for the masticatory problems in patient groups, who are complaining of pain and fatigue during mastication.

  5. Laboratory endurance test of sunflower methyl esters for direct injected diesel engine fuel

    SciTech Connect

    Kaufman, K.; Ziejewski, M.

    1983-12-01

    A methyl ester of sunflower oil was durability tested using the test cycle recommended by the Alternate Fuels Committee of the Engine Manufacturer's Association. The results are compared to a baseline test using diesel fuel. Based on the results, the methyl ester fuel successfully completed the 200-hour durability test.

  6. Biomechanical and Electromyographic Comparisons of Isometric Trunk Flexor Endurance Test Postures: Prone Plank Versus V-Sit.

    PubMed

    Musalem, Lindsay L; Stankovic, Tatjana; Glisic, Drazen; Cook, Gillian E; Beach, Tyson A

    2015-12-01

    The objective of this study was to investigate why holding times on 2 different tests of isometric trunk flexor endurance capacity (prone plank and v-sit) are weakly correlated. Body position and ground reaction force data from 10 men and 10 women were used to conduct static biomechanical analyses of both test postures, and bilateral activations of the rectus abdominis, internal and external obliques, latissimus dorsi, and lumbar and thoracic erector spinae were measured in a second sample of 15 men and 15 women while holding the test postures. No between-posture differences in net low back flexor moments were found (P = .111), but the lumbar spine was 28° more flexed in the v-sit than in the plank (P < .001). No between-posture differences were detected in the rectus abdominis (P = .397), external obliques (P = .204), internal obliques (P = .226), or lumbar erector spinae (P = .116) activation levels, but those of the thoracic erector spinae (P = .0253) and latissimus dorsi (P < .001) were greater in the plank than in the v-sit. Altogether, the findings suggest that differences between plank and v-sit holding times are most likely related to between-test differences in lumbar spine postures and shoulder demands.

  7. Design, construction and long life endurance testing of cathode assemblies for use in microwave high-power transmitting tubes

    NASA Technical Reports Server (NTRS)

    Gorshe, R.

    1982-01-01

    The ability of state of the art cathode types to produce current densities of 2A/sq cm, respectively, over a minimum designed life of 30,000 hours of continuous operation without failures was demonstrated. The performance of the state of the art cathode types was evaluated by endurance testing while operating under identical electrical geometrical, and vacuum conditions that realistically duplicate the operating conditions present in a transmitter tube. Although there has been considerable life testing done on high current density types of cathodes, these have beem primarily limited to diodes. A diode and high power microwave tube are grossly different devices. A comparison of these two devices is provided. A diode and high power microwave tube are quite different; one could therefore assume different internal environments, especially in the cathode region. Therefore, in order to establish life capabilities of the cathodes just mentioned, they should be tested in a vehicle which has an internal environment similar to that of a high power microwave tube.

  8. Effectiveness of the modified progressive aerobic capacity endurance run test for assessing aerobic fitness in Hispanic children who are obese.

    PubMed

    Graham, Marilynn H; Bush, Jill A; Olvera, Norma; Puyau, Maurice R; Butte, Nancy F

    2014-10-01

    The purpose of this study was to evaluate the effectiveness of the progressive aerobic capacity endurance run (PACER) and a newly designed modified PACER (MPACER) for assessing aerobic fitness in Hispanic children who are obese. Thirty-nine (aged 7-12 years) children who were considered obese (≥ 95 th body mass index [BMI] percentile) and 16 children who were considered normal weight (<85th BMI percentile) participated in this study. Performance outcomes included test duration (in minutes) and exercise heart rate (HR) (first-stage and peak HR) for each test. Ninety-five percent confidence intervals and independent t-tests were used to assess differences in primary outcomes. Mean PACER test duration was 1.6 ± 0.6 and 3.1 ± 1.3 minutes for children who were obese and normal weight, respectively. Modified PACER duration was higher than 3 minutes for the obese (3.6 ± 0.6 minutes) and normal weight (5.3 ± 1.2 minutes) groups. Children first-stage HR, expressed as a percent of peak HR, was above the predicted anaerobic threshold during the PACER, but below the anaerobic threshold during the MPACER. Relative first-stage HR was not significantly different between groups for the PACER, but they were significantly different between groups for the MPACER. In conclusion, the MPACER was a better alternative than the PACER for assessing aerobic fitness in Hispanic children who were normal weight and obese. When validated, this modified field test could be used to assess aerobic fitness in Hispanic children, particularly those who are overweight or obese. Additionally, the study provides evidence in which physical educators, personal trainers, and others most apt to assess aerobic fitness in children who are obese, should modify tests originally designed for the population who are normal weight.

  9. Physiological responses to the endurance test of a 3-day-event during hot and cool weather.

    PubMed

    Kohn, C W; Hinchcliff, K W

    1995-11-01

    Physiological data were collected during two 3-day-event competitions: one (H) held in hot and the other (CL) in cool conditions. During H, ambient temperature and relative humidity were 2.5 degrees C-35 degrees C and 74-36% respectively, while during CL, ambient temperature and relative humidity were 7.8 degrees C-8.3 degrees C and 46%-41%, respectively. Rectal temperature, heart and respiratory rates were recorded on arrival at the event, at the end of Phase C and 6 min later, at the end of Phase D and for 30 min at 10 min intervals after each horse finished Phase D (Recovery Period). Because of the heat, the rest-pause during the Endurance Test was extended from 10 to 15 min for horses competing in H, and horses at H were aggressively cooled by repetitive bathing with ice water during the rest-pause and the 30 min Recovery Period. Heart rate was significantly higher (P < 0.05) at the end of Phase C in horses participating at H, as compared to those participating at CL. Heart rates were significantly decreased in both groups after 6 min in the rest-pause and by 10 min after the finish of Phase D. Rectal temperature were significantly higher in horses competing at H than in those competing at CL at the end of Phase C and 6 min later, and at 10 and 20 min after the finish of Phase D. In both groups, rectal temperatures decreased significantly during the first 6 min in the rest-pause and at 10 and 20 min after the finish of Phase D. Fifty-five of 79 (69.6%) horses starting Phase A at H completed Phase D, as compared to 23 of 28 (82.1%) of starters at CL (P > 0.05). Of 10 horses eliminated during the rest-pause at H, 3 were lame, 1 had exertional rhabdomyolysis, 4 were exhausted and 2 were lame and exhausted. Two horses were eliminated during the rest-pause at CL:1 was lame and the other had exertional rhabdomyolysis. There was marked individual variation in horses' responses to heat at H. Heat may have limited the effectiveness of evaporative cooling in horses at H

  10. Load carrying walking test and its relationships to endurance and neuromuscular capabilities in women and men of different ages.

    PubMed

    Holviala, J; Häkkinen, A; Nyman, K; Aho, J; Karavirta, L; Häkkinen, K

    2011-03-01

    The aim of this study was to examine load carrying walking test (TMload) performance on the treadmill and its associations to endurance and neuromuscular capabilities in women and men of different ages. Sixty participants (aged 28 to 71 years) were divided into young, middle-aged and old groups of both genders. Clinical stress test was performed by stationary cycle ergometer (CEload). Peak oxygen uptake (VO2peak), heart rate and lactate concentration were measured using maximal TMload test. Isometric strength and EMG-activity of upper and lower extremities were measured before and after TMload. VO2peak of TMload correlated significantly with TMload exercise time (ET) in all other groups (r=0.67 to 0.91 and p ≤ 0.05 to p<0.001) except old men. Leg extension force decreased (p ≤ 0.05 to p<0.001) after TMload in all groups, grip force in young groups (p ≤ 0.05), while plantar flexion force and all EMGs remained unchanged. In men VO2peak explained 81% and in women VO2peak and age explained 87% of the total variation of the TMload ET. In conclusion, ET of TMload is associated with high VO2peak, but not with muscle strength or its changes during the loading. The present load carrying walking test may be used for testing workers with heavy loading in their occupation or in rehabilitation purposes. Further research is needed to examine in more detailed the loading model of the present study as well as the effects of different types of training on load carrying performance.

  11. Reliability, sensitivity and validity of the assistant referee intermittent endurance test (ARIET) - a modified Yo-Yo IE2 test for elite soccer assistant referees.

    PubMed

    Castagna, Carlo; Bendiksen, Mads; Impellizzeri, Franco M; Krustrup, Peter

    2012-01-01

    We examined the reliability and validity of the assistant referee intermittent endurance test (ARIET), a modified Yo-Yo IE2 test including shuttles of sideways running. The ARIET was carried out on 198 Italian (Serie A-B, Lega-Pro and National Level) and 47 Danish elite soccer assistant referees. Reproducibility was tested for 41 assistant referees on four occasions each separated by one week. The ARIET intraclass correlation coefficients and typical error of measurement ranged from 0.96 to 0.99 and 3.1 to 5.7%, respectively. ARIET performance for Serie A and B was 23 and 25% greater than in Lega-Pro (P < 0.001). The lowest cut-off value derived from receiving operator characteristic discriminating Serie A-B from Lega-Pro was 1300 m. The ARIET performance was significantly correlated with VO(2max) (r = 0.78, P < 0.001), %HR(max) after 4 min of ARIET (r = - 0.81, P < 0.001) and Yo-Yo IR1 performance (r = 0.95, P < 0.001), but not sprint performance (r = -0.15; P = 0.58). The results showed that ARIET is a reproducible and valid test that is able to discriminate between assistant referees of different competitive levels. The lack of correlation with sprinting ability and close correlations with aerobic power, intermittent shuttle running and sub-maximal ARIET heart rate loading provide evidence that ARIET is a relevant test for assessment of intermittent endurance capacity of soccer assistant referees.

  12. Performance and endurance tests of a multipropellant resistojet for space station auxiliary propulsion

    NASA Technical Reports Server (NTRS)

    Morren, W. E.; Whalen, M. V.; Sovey, J. S.

    1986-01-01

    This paper presents the results of an effort to demonstrate the technology readiness of a long-life multipropellant resistojet for space station auxiliary propulsion. Experiments were performed to evaluate the compatibility of grain-stabilized platinum tubes at temperatures up to 1400 deg C in environments of CO2, CH4, NH3, H2O, and H2. All samples tested showed extrapolated lifetimes in excess of 10,000 hr based on 10 percent mass loss as end-of-life. However, samples tested in an ammonia atmosphere at 1400 deg C showed severe pitting, which raised concerns about the compatibility of grain-stabilized platinum with ammonia-containing atmospheres. Additional tests showed that reducing the metal temperature to about 900 deg C (+ or - 100 deg C) significantly reduced this adverse effect.

  13. Square-wave endurance exercise test (SWEET) for training and assessment in trained and untrained subjects. I. Description and cardiorespiratory responses.

    PubMed

    Gimenez, M; Servera, E; Salinas, W

    1982-01-01

    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.

  14. A microcomputer based data acquisition/control system for endurance testing with vegetable oil fuels

    SciTech Connect

    Peterson, C.; Wagner, G.L.

    1982-12-01

    Three hydraulic load stands equipped with Wisconsin 1.0 L air cooled, direct injection engines have been constructed and are being operated with a Hewlett-Packard 85F microcomputer and 3054 Data Logger. The computer will control both the test cycle, according to the Engine Manufacturers Association Guidelines, and analyze and collect the data on-line.

  15. Laboratory endurance test of a sunflower oil blend in a diesel engine

    SciTech Connect

    Ziejewski, M.; Kaufman, K.R.

    1982-01-01

    This paper compares the effects of using a 25 to 75 blend (v/v) of alkali refined sunflower oil and diesel fuel in a diesel engine as compared to a baseline test on diesel fuel. There were no significant problems with engine operation during the baseline test. However, problems were experienced while using the blended fuel. The major problems were (1) abnormal buildup on the injection nozzle tips, (2) injector needle sticking, (3) secondary injection, (4) carbon buildup in the intake ports, (5) carbon deposits on the exhaust valve stems, (6) carbon filling of the compression ring grooves, and (7) abnormal lacquer and varnish buildup on the third piston land. 6 figures, 4 tables.

  16. Real-time and accelerated outdoor endurance testing of solar cells

    NASA Technical Reports Server (NTRS)

    Forestieri, A. F.; Anagnostou, E.

    1978-01-01

    Materials for solar-cell module construction have been studied on the basis of limited real-time outdoor exposure evaluations. The materials tested included transmission samples, sub-modules, and actual solar cells. The results suggest that glass, fluorinated ethylene propylene, and perfluoroalkoxy are good materials for the covering or encapsulation of solar-cell modules. In all cases, dirt accumulation and cleanability are important factors.

  17. Pitfalls during biomechanical testing - Evaluation of different fixation methods for measuring tendons endurance properties.

    PubMed

    Hangody, Gy; Pánics, G; Szebényi, G; Kiss, R; Hangody, L; Pap, K

    2016-03-01

    The goal of the study was to find a proper technique to fix tendon grafts into an INSTRON loading machine. From 8 human cadavers, 40 grafts were collected. We removed the bone-patella tendon-bone grafts, the semitendinosus and gracilis tendons, the quadriceps tendon-bone grafts, the Achilles tendons, and the peroneus longus tendons from each lower extremity. We tested the tendon grafts with five different types of fixation devices: surgical thread (Premicron 3), general mounting clamp, wire mesh, cement fixation, and a modified clamp for an INSTRON loading machine. The mean failure load in case of surgical thread fixation was (381N ± 26N). The results with the general clamp were (527N ± 45N). The wire meshes were more promising (750N ± 21N), but did not reach the outcomes we desired. Easy slippages of the ends of the tendons from the cement encasements were observed (253N ± 18N). We then began to use Shi's clamp that could produce 977N ± 416N peak force. We combined Shi's clamp with freezing of the graft and the rupture of the tendon itself demonstrated an average force of 2198 N ± 773N. We determined that our modified frozen clamp fixed the specimens against high tensile forces.

  18. The Hoff circuit test is more specific than an incremental treadmill test to assess endurance with the ball in youth soccer players.

    PubMed

    Zagatto, A M; Papoti, M; Da Silva, Asr; Barbieri, R A; Campos, E Z; Ferreira, E C; Loures, J P; Chamari, K

    2016-09-01

    The assessment of aerobic endurance is important for training prescription in soccer, and is usually measured by straight running without the ball on a track or treadmill. Due to the ball control and technical demands during a specific soccer test, the running speeds are likely to be lower compared to a continuous incremental test. The aim of the present study was to compare the heart rate (HR), rating of perceived exertion (RPE) and speeds corresponding to 2.0 mmol∙L(-1), 3.5 mmol∙L(-1), lactate threshold (Dmax method) and peak lactate determined in the laboratory and in the Hoff circuit soccer-specific test. Sixteen soccer players (16±1 years) underwent two incremental tests (laboratory and Hoff circuit tests). The speeds were significantly higher in the treadmill test than on the Hoff circuit (2.0 mmol∙L(-1): 9.5±1.2 and 8.1±1.0 km∙h(-1); 3.5 mmol∙L(-1): 12.0±1.2 and 10.2±1.1 km∙h(-1); Dmax: 11.4±1.4 and 9.3±0.4 km∙h(-1); peak lactate: 14.9±1.6 and 10.9±0.8 km∙h(-1)). The HR corresponding to 3.5 mmol∙L-1 was significantly higher on the Hoff circuit compared to the laboratory test (187.5±18.0 and 178.2±17.6 bpm, respectively; P <0.001), while the RPE at the last incremental stage was lower on the Hoff circuit (P < 0.01). The speeds during the Hoff specific soccer test and the HR corresponding to 2.0 mmol∙L(-1), 3.5 mmol∙L(-1) and Dmax/threshold were different compared with the laboratory test. The present study shows that it is possible to assess submaximal endurance related variables specifically in soccer players.

  19. Yo-Yo Intermittent Endurance Test-Level 1 to monitor changes in aerobic fitness in pre-pubertal boys.

    PubMed

    Fernandes, Luís; Krustrup, Peter; Silva, Gustavo; Rebelo, Antonio; Oliveira, José; Brito, João

    2016-01-01

    The present study aimed to examine the performance and heart rate responses during the Yo-Yo Intermittent Endurance Test-Level 1 (Yo-Yo IE1) in children under the age of 10. One hundred and seven male children (7-9 years) performed the Yo-Yo IE1 at the beginning (M1), middle (M2) and end (M3) of the school year. Data from individual heart rate curves of the Yo-Yo IE1 were analysed in order to detect the inflection point between an initial phase of fast rise in heart rate values and a second phase in which the rise of the heart rate values is much smaller. The distance covered in the Yo-Yo IE1 improved from M1 to M3 (884 ± 496 vs. 1032 ± 596 m; p < 0.05; d = 0.27), with intermediate values for M2 (962 ± 528 m). Peak heart rate (HRpeak) decreased from M1 to M2 and M3 (204 ± 9, 202 ± 9 and 200 ± 9 bpm, respectively; p < 0.05; d = 0.25-0.42). The 7th shuttle of the test (280 m), corresponding to 2.5 min, was identified as the inflection point between the two phases. Also, absolute heart rate at the 7th shuttle decreased progressively throughout the year (185 ± 9, 183 ± 10, and 179 ± 10 bpm; p < 0.05; d = 0.31-0.61). The present study provides evidence of the usefulness of a maximal as well as a submaximal version of Yo-Yo IE1 as a tool to monitor changes in aerobic fitness in pre-pubertal children.

  20. Effect of three day bed-rest on circulatory and hormonal responses to active orthostatic test in endurance trained athletes and untrained subjects

    NASA Technical Reports Server (NTRS)

    Kubala, P.; Smorawinski, J.; Kaciuba-Uscilko, H.; Nazar, K.; Bicz, B.; Greenleaf, J. E.

    1996-01-01

    Circulatory and hormonal parameters were measured in endurance-trained athletes and control subjects during orthostatic tolerance tests conducted prior to and after three days of bed rest. Heart rate and blood pressure changes due to bed rest appeared to be the same in both groups. Hormonal changes, however, were different between the two groups, with the athletes having decreased sympathoadrenal activity and increased plasma renin activity. Untrained subjects had changes in cortisol secretion only.

  1. The application of the Yo-Yo intermittent endurance level 2 test to elite female soccer populations.

    PubMed

    Bradley, P S; Bendiksen, M; Dellal, A; Mohr, M; Wilkie, A; Datson, N; Orntoft, C; Zebis, M; Gomez-Diaz, A; Bangsbo, J; Krustrup, P

    2014-02-01

    The aim of this study was to evaluate the application of the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2) to elite female soccer populations. Elite senior (n = 92), youth (n = 42), domestic (n = 46) and sub-elite female soccer players (n = 19) carried out the Yo-Yo IE2 test on numerous occasions across the season. Test-retest coefficient of variation (CV) in Yo-Yo IE2 test performance in domestic female players was 4.5%. Elite senior female players' Yo-Yo IE2 test performances were better (P < 0.01) than elite youth, domestic and sub-elite players (mean ± standard deviation; 1774 ± 532 vs 1490 ± 447, 1261 ± 449, and 994 ± 373 m). For elite senior female players, wide midfielders (2057 ± 550 m) had a higher Yo-Yo IE2 test performance (P < 0.05) than central defenders (1588 ± 534 m) and attackers (1516 ± 401 m), but not central midfielders (1764 ± 473 m) or full-backs (1964 ± 522 m). Large correlations were observed between Yo-Yo IE2 test performance and the total and high-intensity distance covered (r = 0.55; P < 0.05) during elite senior soccer matches (r = 0.70; P < 0.01). A large correlation was also obtained between Yo-Yo IE2 test performance and (r = 0.68; P < 0.01). Performances in the Yo-Yo IE2 test were greater (P < 0.05) in the middle and the end of the season compared with the preparation period for elite youth female players (1767 ± 539 and 1742 ± 503 vs 1564 ± 504 m) and in elite senior female players, Yo-Yo IE2 test performance increased by 14% (P < 0.01) after completing 4 weeks of intense training prior to the FIFA Women's World Cup Finals (2049 ± 283 vs 1803 ± 342 m). The data demonstrate that the Yo-Yo IE2 test is reproducible and is an indicator of the match-specific physical capacity of female soccer players. Furthermore, the Yo-Yo IE2 test illustrates sensitivity by differentiating

  2. Lizard threat display handicaps endurance.

    PubMed Central

    Brandt, Y

    2003-01-01

    Honest-signalling theory asserts that threat displays reliably advertise attributes that influence fighting success. Endurance, as measured by treadmill performance, predicts the outcome of agonistic interactions among lizards. If threat displays in lizards function to advertise endurance capacity then variation in threat displays should correlate with endurance. I tested this prediction for the duration of threat posturing in male side-blotched lizards (Uta stansburiana) and examined whether threat displays act as quality handicaps, reliable signals that expend the attribute that is advertised. Individual variation in the duration of threat posturing correlated with endurance, while an experimental reduction of endurance diminished the duration of threat posturing. As expected of a quality handicap, endurance fell below baseline after display production. A restriction of aerobic metabolism can account for this effect. In threat posturing, lateral compression of the thorax may interfere with respiration or with circulation, limiting aerobic metabolism and causing a compensatory increase in anaerobic metabolism, thereby generating lactate and diminishing locomotor capacity. Concentrations of lactate measured after display production were higher than baseline, consistent with the proposed mechanism. By restricting aerobic metabolism, the threat posture can act as a quality handicap, simultaneously advertising and expending the endurance capacity of displaying lizards. PMID:12803896

  3. Effectiveness of the modified progressive aerobic capacity endurance run test for assessing aerobic fitness in Hispanic children who are obese

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this study was to evaluate the effectiveness of the progressive aerobic capacity endurance run (PACER) and a newly designed modified PACER (MPACER) for assessing aerobic fitness in Hispanic children who are obese. Thirty-nine (aged 7-12 years) children who were considered obese (= 95 ...

  4. An Endurance Test for Project WIN: A Conflict Transformation Program in a Low-Income, Urban, Middle Level Classroom

    ERIC Educational Resources Information Center

    Roberts, Laura; White, George

    2004-01-01

    There are effective conflict transformation programs available for students at the middle level. What is missing is a program designed to have an enduring message, that is, a message that is both positive and vivid. Project WIN provided a positive message by teaching students how to create a justice-based community in their classrooms and the…

  5. High speed testing of the hollow roller bearing

    NASA Astrophysics Data System (ADS)

    Bowen, W. L.; Murphy, T. W., Jr.

    1980-08-01

    This bearing with its preloaded, hollow rollers has the qualities required for high speed operation. Roller hollowness improves cooling ability and its lighter weight reduces the centrifugal force against the raceway. Preloading between inner and outer races for 360 deg insures good roller guidance and minimizes roller skidding. However, the problems of operating a full complement of rollers at very high speeds were unknown. Also, limitations caused by roller bending fatigue needed investigation. To answer these questions, a high speed test machine was constructed and a hollow roller test bearing was designed for operation at 3 million DN. This paper describes the construction of a high speed test cell and subsequent testing of a full complement, preloaded, 115 mm hollow roller bearing. Testing culminated in a successful endurance test of 1000 hours at 26,100 RPM (3 million DN). The results verified several advantages regarding roller stability and antiskidding qualities as well as demonstrating a unique fail-safe condition.

  6. Effects of exercise on alterations in redox homeostasis in elite male and female endurance athletes using a clinical point-of-care test.

    PubMed

    Lewis, Nathan A; Towey, Colin; Bruinvels, Georgie; Howatson, Glyn; Pedlar, Charles R

    2016-10-01

    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.

  7. Specificity of Cardiovascular Endurance Training.

    ERIC Educational Resources Information Center

    Riley, Calberth B., Jr.; Johnson, James H.

    This study determined the specificity of cardiovascular endurance training on a bicycle ergometer. Eighteen male subjects were tested on a heart rate response test of 150 beats per minute on a bicycle ergometer at the pace of 50 revolutions per minute (rpm) and at 160 beats per minute at 60 and 80 rpm, with the resistance equal to the force of…

  8. Influence of Endurance Exercise Overloading Patterns on the Levels of Left Ventricular Catechoamines After a Bout of Lactate Threshold Test in Male Wistar Rat

    PubMed Central

    Azad, Ahmad; Ghasemi, Fatemeh; Rahmani, Ahmad

    2015-01-01

    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

  9. Altitude-Test-Chamber Investigation of the Endurance and Performance Characteristics of the J65-W-7 Engine at a Mach Number of 2.0

    NASA Technical Reports Server (NTRS)

    Biermann, A.E.; Braithwaite, Willis M.

    1955-01-01

    An investigation of the endurance characteristics, at high Mach number, of the J65-W-7 engine was made in an altitude chamber at the Lewis laboratory. The investigation was made to determine whether this engine can be operated at flight conditions of Mach 2 at 35,000-feet altitude (inlet temperature, 250 F) as a limited-service-life engine Failure of the seventh-stage aluminum compressor blades occurred in both engines tested and was attributed to insufficient strength of the blade fastenings at the elevated temperatures. For the conditions of these tests, the results showed that it is reasonable to expect 10 to 15 minutes of satisfactory engine operation before failure. The high temperatures and pressures imposed upon the compressor housing caused no permanent deformation. In general, the performance of the engines tested was only slightly affected by the high ram conditions of this investigation. There was no discernible depreciation of performance with time prior to failure.

  10. The Effects of Low Dose Buccal Administered Caffeine on RPE and Pain during an Upper Body Muscle Endurance Test and Lower Body Anaerobic Test

    ERIC Educational Resources Information Center

    Bellar, David M.; Judge, Lawrence W.; Kamimori, Gary H.; Glickman, Ellen L.

    2012-01-01

    To date there have been a number of studies that have assessed the effects of caffeine on Rated Perceived Exertion (RPE) and Pain Scale scores during continuous exercise. Presently there is little information about the effects of caffeine on RPE and Pain Scale scores during short term, anaerobic and muscle endurance activity. The purpose of the…

  11. Content Validity Index and Intra- and Inter-Rater Reliability of a New Muscle Strength/Endurance Test Battery for Swedish Soldiers.

    PubMed

    Larsson, Helena; Tegern, Matthias; Monnier, Andreas; Skoglund, Jörgen; Helander, Charlotte; Persson, Emelie; Malm, Christer; Broman, Lisbet; Aasa, Ulrika

    2015-01-01

    The objective of this study was to examine the content validity of commonly used muscle performance tests in military personnel and to investigate the reliability of a proposed test battery. For the content validity investigation, thirty selected tests were those described in the literature and/or commonly used in the Nordic and North Atlantic Treaty Organization (NATO) countries. Nine selected experts rated, on a four-point Likert scale, the relevance of these tests in relation to five different work tasks: lifting, carrying equipment on the body or in the hands, climbing, and digging. Thereafter, a content validity index (CVI) was calculated for each work task. The result showed excellent CVI (≥0.78) for sixteen tests, which comprised of one or more of the military work tasks. Three of the tests; the functional lower-limb loading test (the Ranger test), dead-lift with kettlebells, and back extension, showed excellent content validity for four of the work tasks. For the development of a new muscle strength/endurance test battery, these three tests were further supplemented with two other tests, namely, the chins and side-bridge test. The inter-rater reliability was high (intraclass correlation coefficient, ICC2,1 0.99) for all five tests. The intra-rater reliability was good to high (ICC3,1 0.82-0.96) with an acceptable standard error of mean (SEM), except for the side-bridge test (SEM%>15). Thus, the final suggested test battery for a valid and reliable evaluation of soldiers' muscle performance comprised the following four tests; the Ranger test, dead-lift with kettlebells, chins, and back extension test. The criterion-related validity of the test battery should be further evaluated for soldiers exposed to varying physical workload.

  12. Content Validity Index and Intra- and Inter-Rater Reliability of a New Muscle Strength/Endurance Test Battery for Swedish Soldiers

    PubMed Central

    Larsson, Helena; Tegern, Matthias; Monnier, Andreas; Skoglund, Jörgen; Helander, Charlotte; Persson, Emelie; Malm, Christer; Broman, Lisbet; Aasa, Ulrika

    2015-01-01

    The objective of this study was to examine the content validity of commonly used muscle performance tests in military personnel and to investigate the reliability of a proposed test battery. For the content validity investigation, thirty selected tests were those described in the literature and/or commonly used in the Nordic and North Atlantic Treaty Organization (NATO) countries. Nine selected experts rated, on a four-point Likert scale, the relevance of these tests in relation to five different work tasks: lifting, carrying equipment on the body or in the hands, climbing, and digging. Thereafter, a content validity index (CVI) was calculated for each work task. The result showed excellent CVI (≥0.78) for sixteen tests, which comprised of one or more of the military work tasks. Three of the tests; the functional lower-limb loading test (the Ranger test), dead-lift with kettlebells, and back extension, showed excellent content validity for four of the work tasks. For the development of a new muscle strength/endurance test battery, these three tests were further supplemented with two other tests, namely, the chins and side-bridge test. The inter-rater reliability was high (intraclass correlation coefficient, ICC2,1 0.99) for all five tests. The intra-rater reliability was good to high (ICC3,1 0.82–0.96) with an acceptable standard error of mean (SEM), except for the side-bridge test (SEM%>15). Thus, the final suggested test battery for a valid and reliable evaluation of soldiers’ muscle performance comprised the following four tests; the Ranger test, dead-lift with kettlebells, chins, and back extension test. The criterion-related validity of the test battery should be further evaluated for soldiers exposed to varying physical workload. PMID:26177030

  13. Variations in the structure and electrochemical characteristics of membrane electrode assemblies during the endurance testing of hydrogen-air fuel cells

    NASA Astrophysics Data System (ADS)

    Avakov, V. B.; Aliev, A. D.; Bogdanovskaya, V. A.; Ivanitskii, B. A.; Kazanskii, L. P.; Kapustin, A. V.; Korchagin, O. V.; Landgraf, I. K.; Tarasevich, M. P.; Chalykh, A. E.

    2015-05-01

    Variations in the characteristics of a membrane-electrode assembly (MEA) are studied during the endurance testing of a hydrogen-air fuel cell (FC) based on a Nafion 212 proton conducting membrane and platinum catalysts. It is shown that the voltage drop observed during MEA testing was mainly due to physicochemical transformations of the cathode catalyst, i.e., the oxidation of platinum and its subsequent recrystallization with nanoparticle coarsening. It is established that the rate of degradation increases along with temperature and loading, and with periodic FC depressurization. It is concluded that the enhancing effects of additional factors of degradation, e.g., platinum ion transport to the proton-conducting membrane and corrosion of the carbon carrier, were responsible for these processes.

  14. Assessing fitness in endurance horses.

    PubMed

    Fraipont, Audrey; Van Erck, Emmanuelle; Ramery, Eve; Fortier, Guillaume; Lekeux, Pierre; Art, Tatiana

    2012-03-01

    A field test and a standardized treadmill test were used to assess fitness in endurance horses. These tests discriminated horses of different race levels: horses participating in races of 120 km and more showed higher values of VLA4 (velocity at which blood lactate reached 4 mmol/L) and V200 (velocity at which heart rates reached 200 beats per min) than horses of lower race levels.

  15. SOFC Systems with Improved Reliability and Endurance

    SciTech Connect

    Ghezel-Ayagh, Hossein

    2015-12-31

    The overall goal of this U.S. Department of Energy (DOE) sponsored project was the development of Solid Oxide Fuel Cell (SOFC) technology suitable for ultra-efficient central power generation systems utilizing coal and natural gas fuels and featuring greater than 90% carbon dioxide capture. The specific technical objective of this project was to demonstrate, via analyses and testing, progress towards adequate stack life (≥ 4 years) and stack performance stability (degradation rate ≤ 0.2% per 1000 hours) in a low-cost SOFC stack design. This final technical report summarizes the progress made during the project period of 27 months. Significant progress was made in the areas of cell and stack technology development, stack module development, sub-scale module tests, and Proof-of-Concept Module unit design, fabrication and testing. The work focused on cell and stack materials and designs, balance-of-plant improvements, and performance evaluation covering operating conditions and fuel compositions anticipated for commercially-deployed systems. In support of performance evaluation under commercial conditions, this work included the design, fabrication, siting, commissioning, and operation of a ≥ 50 kWe proof-of-concept module (PCM) power plant, based upon SOFC cell and stack technology developed to date by FuelCell Energy, Inc. (FCE) under the Office of Fossil Energy’s Solid Oxide Fuel Cells program. The PCM system was operated for at least 1000 hours on natural gas fuel at FCE’s facility. The factory cost of the SOFC stack was estimated to be at or below the DOE’s high-volume production cost target (2011 $).

  16. Sub-maximal and maximal Yo-Yo intermittent endurance test level 2: heart rate response, reproducibility and application to elite soccer.

    PubMed

    Bradley, Paul S; Mohr, M; Bendiksen, M; Randers, M B; Flindt, M; Barnes, C; Hood, P; Gomez, A; Andersen, Jesper L; Di Mascio, M; Bangsbo, J; Krustrup, P

    2011-06-01

    The aims of this study were to (1) determine the reproducibility of sub-maximal and maximal versions of the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2 test), (2) assess the relationship between the Yo-Yo IE2 test and match performance and (3) quantify the sensitivity of the Yo-Yo IE2 test to detect test-retest changes and discriminate between performance for different playing standards and positions in elite soccer. Elite (n = 148) and sub-elite male (n = 14) soccer players carried out the Yo-Yo IE2 test on several occasions over consecutive seasons. Test-retest coefficient of variation (CV) in Yo-Yo IE2 test performance and heart rate after 6 min were 3.9% (n = 37) and 1.4% (n = 32), respectively. Elite male senior and youth U19 players Yo-Yo IE2 performances were better (P < 0.01) than elite youth U16s and sub-elite players (2,603 ± 451 and 2,534 ± 549 vs. 1,855 ± 535 vs. 1,749 ± 382 m). The intra- and inter-season CV for Yo-Yo IE2 test performance were 4.2 and 5.6%, respectively. A correlation was observed (P < 0.05) between Yo-Yo IE2 test performance and the total (r = 0.74) and high-intensity (r = 0.58) running distance covered in a match. A correlation was also evident (P < 0.01) between Yo-Yo IE2 test heart rate after 6 min expressed in percentage of maximal heart rate and the peak values for high-intensity running performed by midfielders in 5-min (r = -0.71), 15-min (r = -0.75) and 45-min periods (r = -0.77). The present data demonstrate that the Yo-Yo IE2 test is reproducible and can be used to determine the capacity of elite soccer players to perform intense intermittent exercise. Furthermore, the Yo-Yo IE2 test was shown to be a sensitive tool that not only relates to match performance but can also differentiate between intermittent exercise performance of players in various standards, stages of the season and playing positions.

  17. Endurance Tests of a 22-Inch-Diameter Pulse-Jet Engine with a Neoprene-Coated Valve Grid

    DTIC Science & Technology

    1945-10-01

    positions of the valve-grid assembly and the venturi are shown In figure 1. The thrust test stand and the method of simu- lating ram pressure and other...cycle then rop.juto itself at a fre- quency governed by the rosonant frequency of tho ongino tubo . Thrust 3tand ’ind thrust-muaEuring system

  18. Design, construction and long life endurance testing of cathode assemblies for use in microwave high-power transmitting tubes

    NASA Astrophysics Data System (ADS)

    Batra, R.; Marino, D.

    1986-09-01

    The cathode life test program sponsored by NASA Lewis Research Center at Watkins-Johnson Company has been in continuous operation since 1972. Its primary objective has been to evaluate the long life capability of barium dispenser cathodes to produce emission current densities of 2 A sq. cm. or more in an operational environment simulating that of a highpower microwave tube. The life test vehicles were equipped with convergent flow electron guns, drift space tubes with solenoid magnets for electron beam confinement and water-cooled depressed collectors. A variety of cathode types has been tested, including GE Tungstate, Litton Impregnated, Philips Type B and M, Semicon types S and M, and Spectra-Mat Type M. Recent emphasis has been on monitoring the performance of Philips Type M cathodes at 2 A sq. cm. and Sprectra-Mat and Semicon Type M cathodes at 4 A sq. cm. These cathodes have been operated at a constant current of 616 mA and a cathode anode voltage on the order of 10 kV. Cathode temperatures were maintained at 1010 C true as measured from black body holes in the backs of the cathodes. This report presents results of the cathode life test program from July l982 through April l986. The results include hours of operation and performance data in the form of normalized emission current density versus temperature curves (Miram plots).

  19. Design, construction and long life endurance testing of cathode assemblies for use in microwave high-power transmitting tubes

    NASA Technical Reports Server (NTRS)

    Batra, R.; Marino, D.

    1986-01-01

    The cathode life test program sponsored by NASA Lewis Research Center at Watkins-Johnson Company has been in continuous operation since 1972. Its primary objective has been to evaluate the long life capability of barium dispenser cathodes to produce emission current densities of 2 A sq. cm. or more in an operational environment simulating that of a highpower microwave tube. The life test vehicles were equipped with convergent flow electron guns, drift space tubes with solenoid magnets for electron beam confinement and water-cooled depressed collectors. A variety of cathode types has been tested, including GE Tungstate, Litton Impregnated, Philips Type B and M, Semicon types S and M, and Spectra-Mat Type M. Recent emphasis has been on monitoring the performance of Philips Type M cathodes at 2 A sq. cm. and Sprectra-Mat and Semicon Type M cathodes at 4 A sq. cm. These cathodes have been operated at a constant current of 616 mA and a cathode anode voltage on the order of 10 kV. Cathode temperatures were maintained at 1010 C true as measured from black body holes in the backs of the cathodes. This report presents results of the cathode life test program from July l982 through April l986. The results include hours of operation and performance data in the form of normalized emission current density versus temperature curves (Miram plots).

  20. Phosphor bonding studies---burner-rig endurance test. [Bonding of Y/sub 2/O/sub 3/:Eu to turbine blades and vanes

    SciTech Connect

    Beshears, D.L.; Henson, H.M.; Henson, T.J.; Bridges, M.J.; Sadler, R.M.; Cyr, M.A.

    1988-07-01

    This report evaluates two different coating techniques for bonding the thermographic phosphor, europium-doped yttrium oxide (Y/sub 2/O/sub 3/:Eu), to nickel- and cobalt-based high-temperature alloys used in jet engine turbine blades and vanes. The refractory Y/sub 2/O/sub 3/:Eu is suitable for high-temperature surface thermometry when excited by an ultraviolet laser. The fluorescence lifetime of the 611-nm emission has a logarithmic temperature dependence from /approximately/700/degree/C to beyond 1000/degree/C, making it suitable for use as a noncontact temperature-monitoring technique for high-speed, high-temperature turbine engine components. Electron-beam deposition and the plasma-spray coating techniques were used to bond the Y/sub 2/O/sub 3/:Eu to standard Pratt and Whitney turbine blades and vanes. The coated blade and vane samples were then subjected to a standard-burner rig-endurance test for 8 h with a gas temperature of 1525/degree/C. It was concluded that both coating techniques can provide suitable coatings for use in an operating jet turbine engine for the measurement of turbine component temperatures. 41 figs.

  1. Laboratory endurance testing of a 25/75 sunflower oil-diesel fuel blend treated with fuel additives

    SciTech Connect

    Ziejewski, M.; Kaufman, K.R.; Tupa, R.C.

    1984-01-01

    The engine performance and durability effects of a barium smoke suppressant additive, Lubrizol 565, and an ashless polymeric additive, Lubrizol 552, in a 25-75 blend (v/v) of alkali refined sunflower oil with diesel fuel were investigated. The study was performed on a direct injected, turbocharged, and intercooled diesel engine. These additives were tested in an attempt to reduce carbon buildup problems observed while using an untreated 25-75 blend of sunflower oil and diesel fuel.

  2. Laboratory endurance testing of a 25/75 sunflower oil-diesel fuel blend treated with fuel additives

    SciTech Connect

    Ziejewski, M.; Kaufman, K.R.; Tupa, R.C.

    1984-02-01

    The engine performance and durability effects of a barium smoke suppressant additive, Lubrizol 565, and an ashless polymeric additive, Lubrizol 552, in a 25-75 blend (v/v) of alkali refined sunflower oil with diesel fuel were investigated. The study was performed on a direct injected, turbocharged, and intercooled diesel engine. These additives were tested in an attempt to reduce carbon buildup problems observed while using an untreated 25-75 blend of sunflower oil and diesel fuel. Compared to the engine tests on the untreated 25-75 mixture, the barium smoke suppressant additive proved effective in cleaning the inside of injection nozzles (no needle sticking, no carbon build-up inside the orifices), reducing diesel exhaust smoke, and increasing engine power output. However, there was increased residue accumulation in the combustion chamber and on the exterior of the injection nozzle tips. The ashless dispersant additive also improved nozzle cleanliness but did not demonstrate any effect on engine power or cause excessive carbon buildup on the nozzle tips, top of the pistons, and cylinder head. The Lubrizol 552 dispersant looks very promising as an additive for vegetable oil diesel fuel blends for controlling excessive carbon and lacquer deposits.

  3. Quantification of lumbar endurance on a backup lumbar extension dynamometer.

    PubMed

    Hager, Staci M; Udermann, Brian E; Reineke, David M; Gibson, Mark H; Mayer, John M; Murray, Steven R

    2006-01-01

    We evaluated the reliability of static and dynamic lumbar muscle endurance measurements on a BackUP lumbar extension dynamometer. Sixteen healthy participants (8 male; 8 female) volunteered for this investigation. Fifty percent of each participant's body weight was calculated to determine the weight load utilized for the static (holding time) and dynamic (repetitions) lumbar extension endurance tests. Four separate tests (2 static, 2 dynamic) were conducted with at least a 24-hour rest period between tests. Test-retest intraclass correlations were shown to be high (static lumbar endurance, ICC = 0.92 (p < 0.0005); dynamic lumbar endurance, ICC = 0.93 (p < 0.0005) for both of the performed tests. Our results demonstrated that static and dynamic lumbar endurance can be assessed reliably on a BackUP lumbar extension dynamometer. Key PointsReliability studies that test lumbar endurance on machines that effectively stabilize the pelvis and isolate the lumbar extensors are limited.This is the first study to report reliability measures of static and dynamic lumbar endurance on a BackUP lumbar extension dynamometer.Static and dynamic lumbar endurance on a BackUP lumbar extension dynamometer, which uses a variety of pelvic stabilization mechanisms, can be reliably assessed in apparently healthy individuals.Future research is necessary to examine the reliability of lumbar extension endurance on the BackUP dynamometer in patient populations and validity in various settings.

  4. Antioxidant and Antifatigue Properties of the Aqueous Extract of Moringa oleifera in Rats Subjected to Forced Swimming Endurance Test.

    PubMed

    Lamou, Bonoy; Taiwe, Germain Sotoing; Hamadou, André; Abene; Houlray, Justin; Atour, Mahamat Mey; Tan, Paul Vernyuy

    2016-01-01

    The effects of the aqueous extract of Moringa oleifera on swimming performance and related biochemical parameters were investigated in male Wistar rats (130-132 g). Four groups of rats (16 per group) were fed a standard laboratory diet and given distilled water, 100, 200, or 400 mg/kg of extract, respectively, for 28 days. On day 28, 8 rats from each group were subjected to the forced swimming test with tail load (10% of body weight). The remaining 8 rats per group were subjected to the 90-minute free swim. Maximum swimming time, glycemia, lactamia, uremia, triglyceridemia, hepatic and muscle glycogen, hematological parameters, and oxidative stress parameters (superoxide dismutase, catalase, reduced glutathione, and malondialdehyde) were measured. Results. M. oleifera extract increased maximum swimming time, blood hemoglobin, blood glucose, and hepatic and muscle glycogen reserves. The extract also increased the activity of antioxidant enzymes and decreased the blood concentrations of malondialdehyde. Furthermore, it decreased blood concentrations of lactate, triglycerides, and urea. In conclusion, the antifatigue properties of M. oleifera extract are demonstrated by its ability to improve body energy stores and tissue antioxidant capacity and to reduce the tissue build-up of lactic acid.

  5. Solar dynamic heat pipe development and endurance test. Monthly technical progress report number 5, 30 September--28 October, 1987

    SciTech Connect

    Parekh, M.B.

    1987-10-28

    The Space Station requires a high level of reliable electric power. The baseline approach is to utilize a hybrid system in which power is provided by photovoltaic arrays and by solar dynamic power conversion modules. The organic Rankine cycle (ORC) engine is one approach to solar dynamic conversion. The ORC provides the attributes of high efficiency at low temperature and compact simple designs utilizing conventional techniques and materials. The heat receiver is one area which must be addressed in applying the proven ORC to long life applications such as the Space Station. Heat pipes with integral thermal energy storage (TES) canisters and a toluene heater tube are the prime components of the heat receiver from the Phase B preliminary design. This contract is a task order type addressing the design, fabrication and testing of a full scale heat pipe. The contract was initiated on April 16, 1987. Sundstrand has specific responsibilities in each task. Los Alamos National Laboratory (LANL) in turn has the prime contract responsibility to NASA-LeRC.

  6. Solar dynamic heat pipe development and endurance test. Monthly technical progress report number 4, August 28--September 29, 1987

    SciTech Connect

    Parekh, M.B.

    1987-09-29

    The Space Station requires a high level of reliable electric power. The baseline approach is to utilize a hybrid system in which power is provided by photovoltaic arrays and by solar dynamic power conversion modules. The organic Rankine cycle (ORC) engine is one approach to solar dynamic conversion. The ORC provides the attributes of high efficiency at low temperature and compact simple designs utilizing conventional techniques and materials. The heat receiver is one area which must be addressed in applying the proven ORC to long life applications such as the Space Station. Heat pipes with integral thermal energy storage (TES) canisters and a toluene heater tube are the prime components of the heat receiver from the Phase B preliminary design. This contract is a task order type addressing the design, fabrication and testing of a full scale heat pipe. The contract was initiated on April 16, 1987. Sundstrand has specific responsibilities in each task. Los Alamos National Laboratory (LANL) in turn has the prime contract responsibility to NASA-LeRC.

  7. Solar dynamic heat pipe development and endurance test. Monthly technical progress report number 6, 29 October--November 30, 1987

    SciTech Connect

    Parekh, M.B.

    1987-12-07

    The Space Station requires a high level of reliable electric power. The baseline approach is to utilize a hybrid system in which power is provided by photovoltaic arrays and by solar dynamic power conversion modules. The organic Rankine cycle (ORC) engine is one approach to solar dynamic conversion. The ORO provides the attributes of high efficiency at low temperature and compact simple designs utilizing conventional techniques and materials. The heat receiver is one area which must be addressed in applying the proven ORC to long life applications such as the Space Station. Heat pipes with integral thermal energy storage (TES) canisters and a toluene heater tube are the prime components of the heat receiver from the Phase B preliminary design. This contract is a task order type addressing the design, fabrication and testing of a full scale heat pipe. The contract was initiated on April 16, 1987. Sundstrand has specific responsibilities in each task. Los Alamos National Laboratory (LANL) in turn has the prime contract responsibility to NASA-LeRC.

  8. Solar dynamic heat pipe development and endurance test. Monthly technical progress report number 3, 28 July--27 August 1987

    SciTech Connect

    Parekh, M.B.

    1987-09-03

    The Space Station requires a high-level of reliable electric power. The baseline approach is to utilize a hybrid system in which power is provided by photovoltaic arrays and by solar dynamic power conversion modules. The organic Rankine cycle (ORC) engine is one approach to solar dynamic conversion. The ORC provides the attributes of high efficiency at low temperature and compact simple designs utilizing conventional techniques and materials. The heat receiver is one area which must be addressed in applying the proven ORC to long life applications such as the Space Station. Heat pipes with integral thermal energy storage (TES) canisters and a toluene heater tube are the prime components of the heat receiver from the Phase B preliminary design. This contract is a task order type addressing the design, fabrication and testing of a full scale heat pipe. The primary activities during the report period were the fabrication of three 74.4 inch long LiOH canisters and a 72 inch long toluene heater tube. Progress on other tasks and objectives of future tasks are described.

  9. Antioxidant and Antifatigue Properties of the Aqueous Extract of Moringa oleifera in Rats Subjected to Forced Swimming Endurance Test

    PubMed Central

    Lamou, Bonoy; Taiwe, Germain Sotoing; Hamadou, André; Abene; Houlray, Justin; Atour, Mahamat Mey; Tan, Paul Vernyuy

    2016-01-01

    The effects of the aqueous extract of Moringa oleifera on swimming performance and related biochemical parameters were investigated in male Wistar rats (130–132 g). Four groups of rats (16 per group) were fed a standard laboratory diet and given distilled water, 100, 200, or 400 mg/kg of extract, respectively, for 28 days. On day 28, 8 rats from each group were subjected to the forced swimming test with tail load (10% of body weight). The remaining 8 rats per group were subjected to the 90-minute free swim. Maximum swimming time, glycemia, lactamia, uremia, triglyceridemia, hepatic and muscle glycogen, hematological parameters, and oxidative stress parameters (superoxide dismutase, catalase, reduced glutathione, and malondialdehyde) were measured. Results. M. oleifera extract increased maximum swimming time, blood hemoglobin, blood glucose, and hepatic and muscle glycogen reserves. The extract also increased the activity of antioxidant enzymes and decreased the blood concentrations of malondialdehyde. Furthermore, it decreased blood concentrations of lactate, triglycerides, and urea. In conclusion, the antifatigue properties of M. oleifera extract are demonstrated by its ability to improve body energy stores and tissue antioxidant capacity and to reduce the tissue build-up of lactic acid. PMID:26904162

  10. The relationship between cervical flexor endurance, cervical extensor endurance, VAS, and disability in subjects with neck pain

    PubMed Central

    2014-01-01

    Background Several tests have been suggested to assess the isometric endurance of the cervical flexor (NFME) and extensors (NEE) muscles. This study proposes to determine whether neck flexors endurance is related to extensor endurance, and whether cervical muscle endurance is related to disability, pain amount and pain stage in subjects with neck pain. Methods Thirty subjects (18 women, 12 men, mean ± SD age: 43 ± 12 years) complaining of neck pain filled out the Visual Analogue Scale (VAS) and the Neck Pain and Disability Scale-Italian version (NPDS-I). They also completed the timed endurance tests for the cervical muscles. Results The mean endurance was 246.7 ± 150 seconds for the NEE test, and 44.9 ± 25.3 seconds for the NMFE test. A significant correlation was found between the results of these two tests (r = 0.52, p = 0.003). A positive relationship was also found between VAS and NPDS-I (r = 0.549, p = 0.002). The endurance rates were similar for acute/subacute and chronic subjects, whereas males demonstrated significantly higher values compared to females in NFME test. Conclusions These findings suggest that neck flexors and extensors endurance are correlated and that the cervical endurance is not significantly altered by the duration of symptoms in subjects with neck pain. PMID:24581272

  11. Optimization of Heat Treatment Modes of Steel 4Kh5MFS for Metal Conduits of Hot-Chamber Pressure Casting Machines According to Results of Endurance Tests in Molten TsAM-4-1

    NASA Astrophysics Data System (ADS)

    Kolesnikov, M. S.; Mukhametzyanova, G. F.; Zubkov, E. V.

    2016-03-01

    Amethod and a scheme of a device for testing the fatigue endurance and dissolution of die steels in cast melts are presented. The laws of dissolution and the endurance of steel 4Kh5MFS in molten TsAM-4-1 are considered as a function of the mode of the heat treatment, the temperature of the melt, and the torsional deformations. The results of the metallographic studies are used to determine the dominant kinds of fracture of steel 4Kh5MFS in the process of fatigue testing in molten TsAM-4-1 upon variation of the amplitude of the torsional deformation and of the temperature of the melt.

  12. Pulsed Plasma Mission Endurance Test

    DTIC Science & Technology

    1989-08-01

    extremely simple in concept, utilizing a solid propellant (Teflon), a simple electrode geometry (rails), and a common form of energy storage (capacitors...geometry (rails), and a common form of energy storage (capacitors). In application at the micropound level this simplicity demonstrated itself ably in...the fuel bar, which is fed with negator springs into the discharge region between the two electrodes. An energy storage capacitor provides the

  13. Enduring Strategic Rivalries

    DTIC Science & Technology

    2014-08-01

    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

  14. Pregnancy in endurance athletes.

    PubMed

    Penttinen, J; Erkkola, R

    1997-08-01

    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.

  15. 'Endurance': A Daunting Challenge

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 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.

  16. Coaction Effects on a Muscular Endurance Task

    ERIC Educational Resources Information Center

    Martens, Rainer; Landers, Daniel M.

    1969-01-01

    A common procedure in administering muscular endurance tests is to have several individuals perform the same task at the same time. A very old psychological concept known as social facilitation suggests that an individual's performance may be affected by the presence of others. (CK)

  17. Endurance training at altitude.

    PubMed

    Saunders, Philo U; Pyne, David B; Gore, Christopher J

    2009-01-01

    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.

  18. The Temperature of 'Endurance'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The 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).

  19. The Colors of 'Endurance'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 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.

  20. Layers Inside 'Endurance'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 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.

  1. Weird 'Endurance' Rock Ahead

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 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.

  2. TESTING OF THE SECOND GENERATION SPINTEK ROTARY FILTER -11357

    SciTech Connect

    Herman, D.; Poirier, M.; Fowley, M.; Keefer, M.; Huff, T.

    2011-02-02

    The SpinTek rotary microfilter has been developed under the Department of Energy (DOE) Office of Environmental Management (EM) for the purpose of deployment in radioactive service in the DOE complex. The unit that was fabricated and tested is the second generation of the filter that incorporates recommended improvements from previous testing. The completion of this test satisfied a key milestone for the EM technology development program and technology readiness for deployment by Savannah River Remediation in the Small Column Ion Exchange and Sludge Washing processes at the Savannah River Site (SRS). The Savannah River National Laboratory (SRNL) contracted SpinTek Filtration to fabricate a full scale 25 disk rotary filter and perform a 1000 hour endurance test with a simulated SRS sludge. Over 1500 hours of operation have been completed with the filter. SpinTek Filtration fabricated a prototypic 25 disk rotary filter including updates to manufacturing tolerances, an updated design to the rotary joint, improved cooling to the bottom journal, decreases in disk and filter shaft hydraulic resistances. The filter disks were fabricated with 0.5 {micro} pore size, sintered-metal filter media manufactured by Pall Corporation (M050). After fabrication was complete, the filter passed acceptance tests demonstrating rejection of solids and clean water flux with a 50% improvement over the previous filters. Once the acceptance test was complete, a 1000 hour endurance test was initiated simulating a sludge washing process. The test used a simulated SRS Sludge Batch 6 recipe. The insoluble solids started at 5 wt% and were raised to 10 and 15 wt% insoluble solids to simulate the concentration of a large volume tank. The filter system was automated and set up for 24 hour unattended operation. To facilitate this, process control logic was written to operate the filter. During the development it was demonstrated that the method of starting and stopping the filter can affect the build

  3. Reading 'Endurance Crater'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1

    This image shows the area inside 'Endurance Crater' that the Mars Exploration Rover Opportunity has been examining. The rover is investigating the distinct layers of rock that make up this region. Each layer is defined by subtle color and texture variations and represents a separate chapter in Mars' history. The deeper the layer, the further back in time the rocks were formed. Scientists are 'reading' this history book by systematically studying each layer with the rover's scientific instruments. So far, data from the rover indicate that the top layers are sulfate-rich, like the rocks observed in 'Eagle Crater.' This implies that water processes were involved in forming the materials that make up these rocks.

    In figure 1, the layer labeled 'A' in this picture contains broken-up rocks that most closely resemble those of 'Eagle Crater.' Layers 'B,C and D' appear less broken up and more finely laminated. Layer 'E,' on the other hand, looks more like 'A.' At present, the rover is examining layer 'D.'

    So far, data from the rover indicates that the first four layers consist of sulfate-rich, jarosite-containing rocks like those observed in Eagle Crater. This implies that water processes were involved in forming the materials that make up these rocks, though the materials themselves may have been laid down by wind.

    This image was taken by Opportunity's navigation camera on sol 134 (June 9, 2004).

  4. Effects of endurance training only versus same-session combined endurance and strength training on physical performance and serum hormone concentrations in recreational endurance runners.

    PubMed

    Schumann, Moritz; Mykkänen, Olli-Pekka; Doma, Kenji; Mazzolari, Raffaele; Nyman, Kai; Häkkinen, Keijo

    2015-01-01

    This study investigated the effects of endurance training only (E, n = 14) and same-session combined training, when strength training is repeatedly preceded by endurance loading (endurance and strength training (E+S), n = 13) on endurance (1000-m running time during incremental field test) and strength performance (1-repetition maximum (1RM) in dynamic leg press), basal serum hormone concentrations, and endurance loading-induced force and hormone responses in recreationally endurance-trained men. E was identical in the 2 groups and consisted of steady-state and interval running, 4-6 times per week for 24 weeks. E+S performed additional mixed-maximal and explosive-strength training (2 times per week) immediately following an incremental running session (35-45 min, 65%-85% maximal heart rate). E and E+S decreased running time at week 12 (-8% ± 5%, p = 0.001 and -7% ± 3%, p < 0.001) and 24 (-13% ± 5%, p < 0.001 and -9% ± 5%, p = 0.001). Strength performance decreased in E at week 24 (-5% ± 5%, p = 0.014) but was maintained in E+S (between-groups at week 12 and 24, p = 0.014 and 0.011, respectively). Basal serum testosterone and cortisol concentrations remained unaltered in E and E+S but testosterone/sex hormone binding globulin ratio decreased in E+S at week 12 (-19% ± 26%, p = 0.006). At week 0 and 24, endurance loading-induced acute force (-5% to -9%, p = 0.032 to 0.001) and testosterone and cortisol responses (18%-47%, p = 0.013 to p < 0.001) were similar between E and E+S. This study showed no endurance performance benefits when strength training was performed repeatedly after endurance training compared with endurance training only. This was supported by similar acute responses in force and hormonal measures immediately post-endurance loading after the training with sustained 1RM strength in E+S.

  5. Fenitrothion, an organophosphorous insecticide, impairs locomotory function and alters body temperatures in Sminthopsis macroura (Gould 1845) without reducing metabolic rates during running endurance and thermogenic performance tests.

    PubMed

    Story, Paul G; French, Kris; Astheimer, Lee B; Buttemer, William A

    2016-01-01

    Endemic Australian mammal species are exposed to pesticides used for locust control as they occupy the same habitat as the target insect. The authors examined the impact of an ultra-low volume formulation of the organophosphorous insecticide fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenol]-phosphorothioate) on a suite of physiological measures that affect the ability of animals to survive in free-living conditions: locomotory and thermogenic functions, metabolic performance, body mass, and hematocrit and hemoglobin levels. Plasma and brain cholinesterase activity in relation to time since exposure to pesticide were also determined. An orally applied dose of 90 mg kg(-1) fenitrothion reduced running endurance in the stripe-faced dunnart, Sminthopsis macroura, by 80% the day after exposure concomitantly with a reduction of approximately 50% in plasma and 45% in brain acetylcholinesterase activity. These adverse effects disappeared by 10 d postexposure. Maximal metabolic rates reached during running were unaffected by pesticide, as were body mass and hemoglobin and hematocrit levels. Maximal cold-induced metabolic rate (measured as peak 2 min metabolic rate attained during cold exposure), time taken to reach peak metabolic rate on cold exposure, cumulative total oxygen consumed during shivering thermogenesis, and body temperature before and after cold exposure were unaffected by fenitrothion. Dunnart rectal temperatures showed a reduction of up to 5 °C after exposure to fenitrothion but returned to pre-exposure levels by 10 d postdose. Such physiological compromises in otherwise asymptomatic animals demonstrate the importance of considering performance-based measures in pesticide risk assessments.

  6. Mixed Stream Test Rig (MISTER) Startup Report

    SciTech Connect

    Charles Park

    2011-02-01

    This report describes the work accomplished to date to design, procure, assemble, authorize, and startup the Mixed Stream Test Rig (MISTER) at the Idaho National Laboratory (INL). It describes the reasons for establishing this capability, physical configuration of the test equipment, operations methodology, initial success, and plans for completing the initial 1,000 hour test.

  7. Tracking Decrement as a Result of Grip Holding Endurance.

    PubMed

    Bloswick, D S; Ellis, N C

    1974-01-01

    This study explores the feasibility of using the static strength and endurance relationships suggested by Rohmert in 1960 to predict pursuit tracking performance, Ten male subjects are tested on a pursuit rotor before and after being subjected to specific levels of loading on a grip holding device. The loading corresponded to specific levels of each subject's maximum endurance as determined from Rohmert's strength and endurance equation. The hypotheses are: (a) predetermined schedules of strength expenditure cause a systematic decrement in tracking efficiency; and (b) the process of recovering efficiency is dependent upon the expenditure schedules. Resulting data support these hypotheses, suggesting that tracking efficiency can be reliably predicted using some of the strength and endurance relationships postulated by Rohmert.

  8. Altitude and endurance training.

    PubMed

    Rusko, Heikki K; Tikkanen, Heikki O; Peltonen, Juha E

    2004-10-01

    The benefits of living and training at altitude (HiHi) for an improved altitude performance of athletes are clear, but controlled studies for an improved sea-level performance are controversial. The reasons for not having a positive effect of HiHi include: (1) the acclimatization effect may have been insufficient for elite athletes to stimulate an increase in red cell mass/haemoglobin mass because of too low an altitude (< 2000-2200 m) and/or too short an altitude training period (<3-4 weeks); (2) the training effect at altitude may have been compromised due to insufficient training stimuli for enhancing the function of the neuromuscular and cardiovascular systems; and (3) enhanced stress with possible overtraining symptoms and an increased frequency of infections. Moreover, the effects of hypoxia in the brain may influence both training intensity and physiological responses during training at altitude. Thus, interrupting hypoxic exposure by training in normoxia may be a key factor in avoiding or minimizing the noxious effects that are known to occur in chronic hypoxia. When comparing HiHi and HiLo (living high and training low), it is obvious that both can induce a positive acclimatization effect and increase the oxygen transport capacity of blood, at least in 'responders', if certain prerequisites are met. The minimum dose to attain a haematological acclimatization effect is > 12 h a day for at least 3 weeks at an altitude or simulated altitude of 2100-2500 m. Exposure to hypoxia appears to have some positive transfer effects on subsequent training in normoxia during and after HiLo. The increased oxygen transport capacity of blood allows training at higher intensity during and after HiLo in subsequent normoxia, thereby increasing the potential to improve some neuromuscular and cardiovascular determinants of endurance performance. The effects of hypoxic training and intermittent short-term severe hypoxia at rest are not yet clear and they require further study.

  9. Radiation endurance of piezoelectric ultrasonic transducers--a review.

    PubMed

    Sinclair, A N; Chertov, A M

    2015-03-01

    A literature survey is presented on the radiation endurance of piezoelectric ultrasonic transducer components and complete transducer assemblies, as functions of cumulative gamma dose and neutron fluence. The most extensive data on this topic has been acquired in CANDU electrical generating stations, which use piezoelectric ultrasonic transducers manufactured commercially with minor accommodation for high radiation fields. They have been found to be reliable for cumulative gamma doses of up to approximately 2 MegaGrays; a brief summary is made of the associated accommodations required to the transducer design, and the ultimate expected failure modes. Outside of the CANDU experience, endurance data have been acquired under a diverse spectrum of operating conditions; this can impede a direct comparison of the information from different sources. Much of this data is associated with transducers immersed in liquid metal coolants associated with advanced reactor designs. Significant modifications to conventional designs have led to the availability of custom transducers that can endure well over 100 MegaGrays of cumulative gamma dose. Published data on transducer endurance against neutron fluence are reviewed, but are either insufficient, or were reported with inadequate description of test conditions, to make general conclusions on transducer endurance with high confidence. Several test projects are planned or are already underway by major laboratories and research consortia to augment the store of transducer endurance data with respect to both gamma and neutron radiation.

  10. Comparing the Neuropsychological Test Performance of Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) Veterans with and without Blast Exposure, Mild Traumatic Brain Injury, and Posttraumatic Stress Symptoms.

    PubMed

    Storzbach, Daniel; O'Neil, Maya Elin; Roost, Saw-Myo; Kowalski, Halina; Iverson, Grant L; Binder, Laurence M; Fann, Jesse R; Huckans, Marilyn

    2015-05-01

    To compare neuropsychological test performance of Veterans with and without mild traumatic brain injury (MTBI), blast exposure, and posttraumatic stress disorder (PTSD) symptoms. We compared the neuropsychological test performance of 49 Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) Veterans diagnosed with MTBI resulting from combat blast-exposure to that of 20 blast-exposed OEF/OIF Veterans without history of MTBI, 23 OEF/OIF Veterans with no blast exposure or MTBI history, and 40 matched civilian controls. Comparison of neuropsychological test performance across all four participant groups showed a complex pattern of mixed significant and mostly nonsignificant results, with omnibus tests significant for measures of attention, spatial abilities, and executive function. The most consistent pattern was the absence of significant differences between blast-exposed Veterans with MTBI history and blast-exposed Veterans without MTBI history. When blast-exposed Veteran groups with and without MTBI history were aggregated and compared to non-blast-exposed Veterans, there were significant differences for some measures of learning and memory, spatial abilities, and executive function. However, covariation for severity of PTSD symptoms eliminated all significant omnibus neuropsychological differences between Veteran groups. Our results suggest that, although some mild neurocognitive effects were associated with blast exposure, these neurocognitive effects might be better explained by PTSD symptom severity rather than blast exposure or MTBI history alone.

  11. Nutritional Supplements for Endurance Athletes

    NASA Astrophysics Data System (ADS)

    Rasmussen, Christopher J.

    Athletes engaged in heavy endurance training often seek additional nutritional strategies to help maximize performance. Specific nutritional supplements exist to combat certain factors that limit performance beginning with a sound everyday diet. Research has further demonstrated that safe, effective, legal supplements are in fact available for today's endurance athletes. Several of these supplements are marketed not only to aid performance but also to combat the immunosuppressive effects of intense endurance training. It is imperative for each athlete to research the legality of certain supplements for their specific sport or event. Once the legality has been established, it is often up to each individual athlete to decipher the ethics involved with ingesting nutritional supplements with the sole intent of improving performance.

  12. Iron and the endurance athlete.

    PubMed

    Hinton, Pamela S

    2014-09-01

    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.

  13. How Cells Endure Extreme Conditions

    SciTech Connect

    2009-01-01

    One of natures most gripping feats of survival is now better understood. For the first time, Berkeley Lab scientists observed the chemical changes in individual cells that enable them to survive in conditions that should kill them. http://newscenter.lbl.gov/feature-stories/2009/07/07/cells-endure-extremes/

  14. Atrial fibrillation in endurance athletes.

    PubMed

    Wilhelm, Matthias

    2014-08-01

    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

  15. 46 CFR 164.018-11 - Approval tests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... and then retested in the chamber at that temperature. (5) Reflective intensity. (6) Resistance to... “resistance to accelerated weathering” test method must be performed for 250 hours, if testing Type I material, and for 1,000 hours if testing Type II material.) (7) Resistance to heat, cold, and humidity....

  16. Effects of Dining on Tongue Endurance and Swallowing-Related Outcomes

    ERIC Educational Resources Information Center

    Kays, Stephanie A.; Hind, Jacqueline A.; Gangnon, Ronald E.; Robbins, JoAnne

    2010-01-01

    Purpose: The purpose of this study was to test the hypothesis that eating a meal reduces tongue strength and endurance in healthy old and young adults. It was predicted that older adults would show greater declines in tongue endurance while demonstrating higher perceived effort, longer meal durations, and clinical signs of swallowing difficulty.…

  17. Effects of Manual Negative Accentuated Resistance on Strength and/or Muscular Endurance.

    ERIC Educational Resources Information Center

    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…

  18. Endurance factors improve hippocampal neurogenesis and spatial memory in mice

    PubMed Central

    Kobilo, Tali; Yuan, Chunyan; van Praag, Henriette

    2011-01-01

    Physical activity improves learning and hippocampal neurogenesis. It is unknown whether compounds that increase endurance in muscle also enhance cognition. We investigated the effects of endurance factors, peroxisome proliferator-activated receptor δ agonist GW501516 and AICAR, activator of AMP-activated protein kinase on memory and neurogenesis. Mice were injected with GW for 7 d or AICAR for 7 or 14 d. Two weeks thereafter mice were tested in the Morris water maze. AICAR (7 d) and GW improved spatial memory. Moreover, AICAR significantly, and GW modestly, elevated dentate gyrus neurogenesis. Thus, pharmacological activation of skeletal muscle may mediate cognitive effects. PMID:21245211

  19. 'Endurance' Goal Across the Plains

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This mosaic image from the Mars Exploration Rover Opportunity's panoramic camera provides an overview of the rover's drive direction toward 'Endurance Crater,' which is in the upper right corner of image.

    The plains appear to be uniform in character from the rovers current position all the way to Endurance Crater. Granules of various sizes blanket the plains. Spherical granules fancifully called blueberries are present some intact and some broken. Larger granules pave the surface, while smaller grains, including broken blueberries, form small dunes. Randomly distributed 1-centimeter (0.4 inch) sized pebbles (as seen just left of center in the foreground of the image) make up a third type of feature on the plains. The pebbles' composition remains to be determined. Scientists plan to examine these in the coming sols.

    Examination of this part of Mars by NASA's Mars Global Surveyor orbiter revealed the presence of hematite, which led NASA to choose Meridiani Planum as Opportunity's landing site. The rover science conducted on the plains of Meridiani Planum serves to integrate what the rovers are seeing on the ground with what orbital data have shown.

    Opportunity will make stop at a small crater called 'Fram' (seen in the upper left, with relatively large rocks nearby) before heading to the rim of Endurance Crater.

  20. Common problems in endurance athletes.

    PubMed

    Cosca, David D; Navazio, Franco

    2007-07-15

    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.

  1. Instructions to Adopt an External Focus Enhance Muscular Endurance

    ERIC Educational Resources Information Center

    Marchant, David C.; Greig, Matt; Bullough, Jonathan; Hitchen, Daniel

    2011-01-01

    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…

  2. Cardiopulmonary Fitness and Endurance in Children with Developmental Coordination Disorder

    ERIC Educational Resources Information Center

    Wu, Sheng K.; Lin, Hsiao-Hui; Li, Yao-Chuen; Tsai, Chia-Liang; Cairney, John

    2010-01-01

    The purpose of this study was to compare cardiopulmonary fitness and endurance in 9-11-year-old children with DCD against a group of typically developing children in Taiwan. The Movement ABC test was used to evaluate the motor abilities of children. Forty-one participants (20 children with DCD and 21 children without DCD) were recruited for this…

  3. No Evidence of a Common DNA Variant Profile Specific to World Class Endurance Athletes.

    PubMed

    Rankinen, Tuomo; Fuku, Noriyuki; Wolfarth, Bernd; Wang, Guan; Sarzynski, Mark A; Alexeev, Dmitry G; Ahmetov, Ildus I; Boulay, Marcel R; Cieszczyk, Pawel; Eynon, Nir; Filipenko, Maxim L; Garton, Fleur C; Generozov, Edward V; Govorun, Vadim M; Houweling, Peter J; Kawahara, Takashi; Kostryukova, Elena S; Kulemin, Nickolay A; Larin, Andrey K; Maciejewska-Karłowska, Agnieszka; Miyachi, Motohiko; Muniesa, Carlos A; Murakami, Haruka; Ospanova, Elena A; Padmanabhan, Sandosh; Pavlenko, Alexander V; Pyankova, Olga N; Santiago, Catalina; Sawczuk, Marek; Scott, Robert A; Uyba, Vladimir V; Yvert, Thomas; Perusse, Louis; Ghosh, Sujoy; Rauramaa, Rainer; North, Kathryn N; Lucia, Alejandro; Pitsiladis, Yannis; Bouchard, Claude

    2016-01-01

    There are strong genetic components to cardiorespiratory fitness and its response to exercise training. It would be useful to understand the differences in the genomic profile of highly trained endurance athletes of world class caliber and sedentary controls. An international consortium (GAMES) was established in order to compare elite endurance athletes and ethnicity-matched controls in a case-control study design. Genome-wide association studies were undertaken on two cohorts of elite endurance athletes and controls (GENATHLETE and Japanese endurance runners), from which a panel of 45 promising markers was identified. These markers were tested for replication in seven additional cohorts of endurance athletes and controls: from Australia, Ethiopia, Japan, Kenya, Poland, Russia and Spain. The study is based on a total of 1520 endurance athletes (835 who took part in endurance events in World Championships and/or Olympic Games) and 2760 controls. We hypothesized that world-class athletes are likely to be characterized by an even higher concentration of endurance performance alleles and we performed separate analyses on this subsample. The meta-analysis of all available studies revealed one statistically significant marker (rs558129 at GALNTL6 locus, p = 0.0002), even after correcting for multiple testing. As shown by the low heterogeneity index (I2 = 0), all eight cohorts showed the same direction of association with rs558129, even though p-values varied across the individual studies. In summary, this study did not identify a panel of genomic variants common to these elite endurance athlete groups. Since GAMES was underpowered to identify alleles with small effect sizes, some of the suggestive leads identified should be explored in expanded comparisons of world-class endurance athletes and sedentary controls and in tightly controlled exercise training studies. Such studies have the potential to illuminate the biology not only of world class endurance performance but

  4. No Evidence of a Common DNA Variant Profile Specific to World Class Endurance Athletes

    PubMed Central

    Wolfarth, Bernd; Wang, Guan; Sarzynski, Mark A.; Alexeev, Dmitry G.; Ahmetov, Ildus I.; Boulay, Marcel R.; Cieszczyk, Pawel; Eynon, Nir; Filipenko, Maxim L.; Garton, Fleur C.; Generozov, Edward V.; Govorun, Vadim M.; Houweling, Peter J.; Kawahara, Takashi; Kostryukova, Elena S.; Kulemin, Nickolay A.; Larin, Andrey K.; Maciejewska-Karłowska, Agnieszka; Miyachi, Motohiko; Muniesa, Carlos A.; Murakami, Haruka; Ospanova, Elena A.; Padmanabhan, Sandosh; Pavlenko, Alexander V.; Pyankova, Olga N.; Santiago, Catalina; Sawczuk, Marek; Scott, Robert A.; Uyba, Vladimir V.; Yvert, Thomas; Perusse, Louis; Ghosh, Sujoy; Rauramaa, Rainer; North, Kathryn N.; Lucia, Alejandro; Pitsiladis, Yannis; Bouchard, Claude

    2016-01-01

    There are strong genetic components to cardiorespiratory fitness and its response to exercise training. It would be useful to understand the differences in the genomic profile of highly trained endurance athletes of world class caliber and sedentary controls. An international consortium (GAMES) was established in order to compare elite endurance athletes and ethnicity-matched controls in a case-control study design. Genome-wide association studies were undertaken on two cohorts of elite endurance athletes and controls (GENATHLETE and Japanese endurance runners), from which a panel of 45 promising markers was identified. These markers were tested for replication in seven additional cohorts of endurance athletes and controls: from Australia, Ethiopia, Japan, Kenya, Poland, Russia and Spain. The study is based on a total of 1520 endurance athletes (835 who took part in endurance events in World Championships and/or Olympic Games) and 2760 controls. We hypothesized that world-class athletes are likely to be characterized by an even higher concentration of endurance performance alleles and we performed separate analyses on this subsample. The meta-analysis of all available studies revealed one statistically significant marker (rs558129 at GALNTL6 locus, p = 0.0002), even after correcting for multiple testing. As shown by the low heterogeneity index (I2 = 0), all eight cohorts showed the same direction of association with rs558129, even though p-values varied across the individual studies. In summary, this study did not identify a panel of genomic variants common to these elite endurance athlete groups. Since GAMES was underpowered to identify alleles with small effect sizes, some of the suggestive leads identified should be explored in expanded comparisons of world-class endurance athletes and sedentary controls and in tightly controlled exercise training studies. Such studies have the potential to illuminate the biology not only of world class endurance performance but

  5. Hodgkin's Lymphoma in an elite endurance athlete.

    PubMed

    Schumacher, Yorck Olaf; Muser, Klaus; Hirschberger, Barbara; Roecker, Kai; Dickhuth, Hans Herrmann; Pottgiesser, Torben

    2008-03-01

    Cancer is a life-threatening condition. We describe the case of a 22-yr-old world-class endurance athlete who presented with mild local lymphadenopathy but without any systemic complaints or impaired performance. He was subsequently diagnosed with stage III A (S) Hodgkin's lymphoma. A complete physiological workup before the diagnosis revealed high aerobic capacity. Immediately after six courses of escalated BEACOPP chemotherapy in an identical test setting, aerobic capacity was markedly reduced (-42%), mainly because of a decrease in total hemoglobin mass (-37%), despite maintaining a certain amount of endurance training. Other potentially performance-limiting systems such as heart, lung, or aerobic metabolism did not show any signs of impairment. Two months after chemotherapy, the athlete had recovered his hemoglobin mass, and his aerobic performance was almost back to pretherapy levels. This case illustrates that advanced malignancies can be present in elite athletes without affecting performance, and that aerobic capacity can be regained within a short time after systemic chemotherapy.

  6. The limits of endurance exercise.

    PubMed

    Noakes, Timothy David

    2006-09-01

    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

  7. "Losing Battles": The Tests of Endurance.

    ERIC Educational Resources Information Center

    Rienstra, Phillis

    The works of Eudora Welty challenge the abilities of the oral reader who wishes to interpret them properly. Her novel, "Losing Battles," requires careful attention to the narrative point of view as a guide to its various dimensions of meaning. The narrative shifts through the consciousnesses of various characters of four generations in a rural…

  8. Mountain Bike Wheel Endurance Testing and Modeling

    DTIC Science & Technology

    2012-01-01

    simulating bike and rider mass, is added using weights supported near the wheel hub axis. The pivoting assembly is raised and lowered on pneumatic ...A lower frequency oscillation with period ~0.2 seconds corresponds with the 5 Hz natural frequency of the weighted pivot arm on the pneumatic tire...Empirical Model for Determining the Radial Force-Deflection Characteristics of Off-Road bicycle Tyres ,” International Journal of Vehicle Design, 17 (4

  9. 14 CFR 33.87 - Endurance test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .... (ii) During the runs at any rated augmented thrust the hydraulic fluid temperature must be maintained... engines with augmented takeoff power ratings that involve increases in turbine inlet temperature, rotor speed, or shaft power, this period of running at takeoff must be at the augmented rating. For...

  10. Durability testing at one atmosphere of advanced catalysts and catalyst supports for automotive gas turbine engine combustors, part 1

    NASA Technical Reports Server (NTRS)

    Heck, R. M.; Chang, M.; Hess, H.; Carrubba, R.

    1977-01-01

    The durability of catalysts and catalyst supports in a combustion environment was experimentally demonstrated. A test of 1000 hours duration was completed with two catalysts, using diesel fuel and operating at catalytically supported thermal combustion conditions. The performance of the catalysts was determined by monitoring emissions throughout the test, and by examining the physical condition of the catalyst core at the conclusion of the test. The test catalysts proved to be capable of low emissions operation after 1000 hours diesel aging, with no apparent physical degradation of the catalyst support.

  11. Seeing 'Endurance' Through Infrared Eyes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Surface composition in 'Endurance Crater' is mapped with color-coded interpretation of data from the miniature thermal emission spectrometer on NASA's Mars Exploration Rover Opportunity. The information has been overlaid onto a view of the crater from Opportunity's panoramic camera. Green, such as on some slopes, indicates material rich in the mineral hematite. Blue and purple, such as on some cliffs of exposed rock, indicate the presence of basalt. Basaltic material is volcanic in origin, but the basalt may have been broken down into sand by weathering, then re-deposited by wind or water. Red indicates areas covered by martian dust.

  12. [Fasting and physical endurance capacity].

    PubMed

    Schürch, P M

    1993-03-01

    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.

  13. Endurance bounds of aerial systems

    NASA Astrophysics Data System (ADS)

    Harrington, Aaron M.; Kroninger, Christopher M.

    2014-06-01

    Within the past few years micro aerial vehicles (MAVs) have received much more attention and are starting to proliferate into military as well as civilian roles. However, one of the major drawbacks for this technology currently, has been their poor endurance, usually below 10 minutes. This is a direct result of the inefficiencies inherent in their design. Often times, designers do not consider the various components in the vehicle design and match their performance to the desired mission for the vehicle. These vehicles lack a prescribed set of design guidelines or empirically derived design equations which often limits their design to selection of commercial off-the-shelf components without proper consideration of their affect on vehicle performance. In the current study, the design space for different vehicle configurations has been examined including insect flapping, avian flapping, rotary wing, and fixed wing, and their performance bounds are established. The propulsion system typical of a rotary wing vehicle is analyzed to establish current baselines for efficiency of vehicles at this scale. The power draw from communications is analyzed to determine its impact on vehicle performance. Finally, a representative fixed wing MAV is examined and the effects of adaptive structures as a means for increasing vehicle endurance and range are examined. This paper seeks to establish the performance bounds for micro air vehicles and establish a path forward for future designs so that efficiency may be maximized.

  14. Noninvasive measurement of respiratory muscle performance after exhaustive endurance exercise.

    PubMed

    Perret, C; Pfeiffer, R; Boutellier, U; Wey, H M; Spengler, C M

    1999-08-01

    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.

  15. Endurance and Other Properties at Low Temperatures of Some Alloys for Aircraft Use

    NASA Technical Reports Server (NTRS)

    Russell, H W; Welcker, W A , Jr

    1931-01-01

    The low temperature endurance properties of materials for aircraft construction are not well known. In order to determine them, apparatus for testing endurance at -40 C has been devised. The endurance properties of monel metal, low-carbon stainless steel, "18 and *, " 3 1/2% Ni steel and chromium-molybdenum steel have been determined at -40 C and at room temperature about +20 C. Tensile, impact and hardness tests of these materials have also been made at various temperatures. The results show an increase in endurance limit, tensile strength, and hardness with decreased temperature. Impact strength is, in general, decreased, but of all the alloys tested, only one, low-carbon stainless steel, gives less than 15 ft. lb. Chrpay impact test at -40 C.

  16. Long endurance materials for aluminum fuel cell systems

    SciTech Connect

    Hall, S.E.; Carter, D.L.; Weber, C.L.

    1995-12-31

    Appropriate selection of long endurance materials is critical to the cost effective use of fuel cell technology for near-term commercial and defense applications. To effectively transition this technology from laboratory prototype to fielded system, the durability of all fuel cell subsystems must be addressed. Material selection based upon a thorough understanding of system performance requirements, operational environments, and user interfaces not only provides high reliability and enhanced safety, but also lowers life cycle costs. This paper discusses the development of an Aluminum Fuel Cell Power System (FCPS) for the Advanced Research Projects Agency (ARPA) Unmanned Underwater Vehicle (UUV) program, focusing on the operational endurance testing that was conducted to evaluate candidate materials for cell stack, electrolyte, and coolant subsystems. The FCPS is a 15 kW closed aluminum-oxygen fuel cell system that provides up to 1.1 MWh energy. Loral has completed small-scale bench tests and is currently fabricating a full-scale system to be demonstrated in 1995. A materials/component endurance test program was established and conducted early in the design phase of the FCPS program. To date, Loral has completed over 3,000 operational test hours, with nearly 8,000 hours of accumulated exposure to KOH. Results of these tests have been incorporated into the FCPS detailed design, and are expected to significantly enhance the performance of the fielded system. This program is sponsored by ARPA Maritime Systems Technology Office under NASA contract NAS3-26715.

  17. Myasthenia gravis and endurance exercise.

    PubMed

    Scheer, Bernd Volker; Valero-Burgos, Encarna; Costa, Ricardo

    2012-08-01

    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.

  18. Effect of resistance training regimens on treadmill running and neuromuscular performance in recreational endurance runners.

    PubMed

    Mikkola, Jussi; Vesterinen, Ville; Taipale, Ritva; Capostagno, Benoit; Häkkinen, Keijo; Nummela, Ari

    2011-10-01

    The purpose of this study was to assess the effects of heavy resistance, explosive resistance, and muscle endurance training on neuromuscular, endurance, and high-intensity running performance in recreational endurance runners. Twenty-seven male runners were divided into one of three groups: heavy resistance, explosive resistance or muscle endurance training. After 6 weeks of preparatory training, the groups underwent an 8-week resistance training programme as a supplement to endurance training. Before and after the 8-week training period, maximal strength (one-repetition maximum), electromyographic activity of the leg extensors, countermovement jump height, maximal speed in the maximal anaerobic running test, maximal endurance performance, maximal oxygen uptake ([V·]O(₂max)), and running economy were assessed. Maximal strength improved in the heavy (P = 0.034, effect size ES = 0.38) and explosive resistance training groups (P = 0.003, ES = 0.67) with increases in leg muscle activation (heavy: P = 0.032, ES = 0.38; explosive: P = 0.002, ES = 0.77). Only the heavy resistance training group improved maximal running speed in the maximal anaerobic running test (P = 0.012, ES = 0.52) and jump height (P = 0.006, ES = 0.59). Maximal endurance running performance was improved in all groups (heavy: P = 0.005, ES = 0.56; explosive: P = 0.034, ES = 0.39; muscle endurance: P = 0.001, ES = 0.94), with small though not statistically significant improvements in [V·]O(₂max) (heavy: ES = 0.08; explosive: ES = 0.29; muscle endurance: ES = 0.65) and running economy (ES in all groups < 0.08). All three modes of strength training used concurrently with endurance training were effective in improving treadmill running endurance performance. However, both heavy and explosive strength training were beneficial in improving neuromuscular characteristics, and heavy resistance training in particular contributed to improvements in high-intensity running characteristics. Thus, endurance

  19. 40 CFR 1054.245 - How do I determine deterioration factors from exhaust durability testing?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... factor using a linear least-squares fit of your test data, but treat the low-hour test point as occurring... the engine over a representative duty cycle for a period at least as long as the useful life (in hours... occurred after at least 80 percent of the useful life. (8) If your useful life is 1,000 hours or...

  20. 40 CFR 1054.245 - How do I determine deterioration factors from exhaust durability testing?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... factor using a linear least-squares fit of your test data, but treat the low-hour test point as occurring... the engine over a representative duty cycle for a period at least as long as the useful life (in hours... occurred after at least 80 percent of the useful life. (8) If your useful life is 1,000 hours or...

  1. 40 CFR 1054.245 - How do I determine deterioration factors from exhaust durability testing?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... factor using a linear least-squares fit of your test data, but treat the low-hour test point as occurring... the engine over a representative duty cycle for a period at least as long as the useful life (in hours... occurred after at least 80 percent of the useful life. (8) If your useful life is 1,000 hours or...

  2. 40 CFR 1054.245 - How do I determine deterioration factors from exhaust durability testing?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... factor using a linear least-squares fit of your test data, but treat the low-hour test point as occurring... the engine over a representative duty cycle for a period at least as long as the useful life (in hours... occurred after at least 80 percent of the useful life. (8) If your useful life is 1,000 hours or...

  3. Effects of Dining on Tongue Endurance and Swallowing-Related Outcomes

    PubMed Central

    Kays, Stephanie A.; Hind, Jacqueline A.; Gangnon, Ronald E.; Robbins, JoAnne

    2011-01-01

    Purpose The purpose of this study was to test the hypothesis that eating a meal reduces tongue strength and endurance in healthy old and young adults. It was predicted that older adults would show greater declines in tongue endurance, while demonstrating higher perceived effort, longer meal durations, and clinical signs of swallowing difficulty. Methods Twenty-two healthy adults were enrolled into two groups (ages 20-35 years & 65-82 years, each including 5M, 6F). Maximum tongue strength (Pmax) and endurance (duration 50% of Pmax could be maintained) were measured twice at baseline and once post-meal. Subjects consumed half of a bagel with peanut butter, carrot sticks and milk between measures. Results All subjects demonstrated reduced tongue strength and endurance post-meal. Young adults showed a greater decline in anterior tongue endurance compared with older adults (p=0.05). There was no evidence that changes in tongue strength, perceived effort or meal duration varied by age or gender. The three oldest subjects reported the highest effort and displayed signs of difficulty swallowing while dining. Conclusions Young and old adults demonstrated reduced tongue strength and endurance after dining, but younger subjects showed greater declines in anterior tongue endurance while older adults exhibited signs of swallowing difficulty. PMID:20689047

  4. The Effects of Preexercise Caffeinated Coffee Ingestion on Endurance Performance: An Evidence-Based Review.

    PubMed

    Higgins, Simon; Straight, Chad R; Lewis, Richard D

    2016-06-01

    Endurance athletes commonly ingest caffeine as a means to enhance training intensity and competitive performance. A widely-used source of caffeine is coffee, however conflicting evidence exists regarding the efficacy of coffee in improving endurance performance. In this context, the aims of this evidence-based review were threefold: 1) to evaluate the effects of preexercise coffee on endurance performance, 2) to evaluate the effects of coffee on perceived exertion during endurance performance, and 3) to translate the research into usable information for athletes to make an informed decision regarding the intake of caffeine via coffee as a potential ergogenic aid. Searches of three major databases were performed using terms caffeine and coffee, or coffee-caffeine, and endurance, or aerobic. Included studies (n = 9) evaluated the effects of caffeinated coffee on human subjects, provided the caffeine dose administered, administered caffeine ≥ 45 min before testing, and included a measure of endurance performance (e.g., time trial). Significant improvements in endurance performance were observed in five of nine studies, which were on average 24.2% over controls for time to exhaustion trials, and 3.1% for time to completion trials. Three of six studies found that coffee reduced perceived exertion during performance measures significantly more than control conditions (p < .05). Based on the reviewed studies there is moderate evidence supporting the use of coffee as an ergogenic aid to improve performance in endurance cycling and running. Coffee providing 3-8.1 mg/kg (1.36-3.68 mg/lb) of caffeine may be used as a safe alternative to anhydrous caffeine to improve endurance performance.

  5. Long endurance underwater power system

    NASA Astrophysics Data System (ADS)

    1989-01-01

    The development and design of deep sea power sources for long endurances (more than 1 year) and moderate power (more than 1 KW) are unique. The best primary battery (Li-thionyl chloride) would involve huge space and weight and the cost of such a system would be prohibitive. Fuel cells with stored gases need a pressure vessel and also quite a large volume and weight. Aquanautics is engaged in developing a power source to a very demanding design. The design would involve a completely open system eliminating the need for a pressure vessel. Aquanautics will capture oxygen from the seawater to be delivered to a fuel cell. The hydrogen generated in this design is envisioned to be from a reaction between aluminum and seawater. Such a completely open system is already available from Alupower, Inc. This provides for a much safer and more compact design than cryogenic hydrogen. Lithium or magnesium can also be used. Both are expensive and lithium is known to be potentially hazardous. Since the last report, there has been major improvement of the technological issue of carrier longevity. The previous carrier had an operational life of 3 days. At present, Aquanautics has discovered a carrier called 23SuzyP which has stable electrochemical performance for over a month.

  6. Correlation between Limb Muscle Endurance, Strength, and Functional Capacity in People with Chronic Obstructive Pulmonary Disease

    PubMed Central

    Törnberg, Anna; Wadell, Karin

    2016-01-01

    Purpose: To examine the correlation between limb muscle function (endurance and strength) and functional capacity in upper limbs (ULs) and lower limbs (LLs) of people with chronic obstructive pulmonary disease (COPD). Method: This article describes a secondary analysis of data from a randomized controlled trial. A stationary dynamometer was used to measure isokinetic muscle strength and endurance; the 6-minute walk test, the 6-minute pegboard and ring test, and the unsupported UL exercise test were used to measure functional capacity. Results: Participants were 44 adults with COPD. Muscle strength and endurance in ULs and LLs demonstrated a moderate to strong correlation with functional capacity. When controlling for muscle strength, muscle endurance was moderately correlated with functional capacity in ULs and LLs, but when controlling for muscle endurance, there was no positive and significant correlation between muscle strength and functional capacity for the ULs or LLs. Conclusions: Functional capacity seems to be more closely related to limb muscle endurance than to limb muscle strength in people with COPD. PMID:27504047

  7. Caffeine and taurine enhance endurance performance.

    PubMed

    Imagawa, T F; Hirano, I; Utsuki, K; Horie, M; Naka, A; Matsumoto, K; Imagawa, S

    2009-07-01

    Caffeine enhances endurance performance; however, its effect on accumulated lactate remains unclear. Conversely, taurine, which also enhances endurance performance, decreases accumulated lactate. In this study, the effect of combination of caffeine and taurine on endurance performance was assessed. Mice ran on a treadmill, and the accumulated lactate was measured. In addition, muscle fibers from the gastrocnemius muscle of the mice were stained with ATPase and analyzed. The use of caffeine and taurine over a 2 week period enhanced endurance performance. Moreover, taurine significantly decreased the accumulated concentration of lactate over long running distances. However, the diameter of the cross-sections and ratios of Types I, IIA, and IIB muscle fibers were not affected.

  8. Feeding management of elite endurance horses.

    PubMed

    Harris, Patricia

    2009-04-01

    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.

  9. 14 CFR 33.85 - Calibration tests.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... essential for engine functioning. (b) A power check at sea level conditions must be accomplished on the endurance test engine after the endurance test and any change in power characteristics which occurs...

  10. Y chromosome haplogroups of elite Ethiopian endurance runners.

    PubMed

    Moran, Colin N; Scott, Robert A; Adams, Susan M; Warrington, Samantha J; Jobling, Mark A; Wilson, Richard H; Goodwin, William H; Georgiades, Evelina; Wolde, Bezabhe; Pitsiladis, Yannis P

    2004-11-01

    Favourable genetic endowment has been proposed as part of the explanation for the success of East African endurance athletes, but no evidence has yet been presented. The Y chromosome haplogroup distribution of elite Ethiopian athletes (n=62) was compared with that of the general Ethiopian population (n=95) and a control group from Arsi (a region producing a disproportionate number of athletes; n=85). Athletes belonged to three groups: marathon runners (M; n=23), 5-km to 10-km runners (5-10K; n=21) and other track and field athletes (TF; n=18). DNA was extracted from buccal swabs and haplogroups were assigned after the typing of binary markers in multiplexed minisequencing reactions. Frequency differences between groups were assessed by using contingency exact tests and showed that Y chromosome haplogroups are not distributed amongst elite Ethiopian endurance runners in the same proportions as in the general population, with statistically significant (P<0.05) differences being found in four of the individual haplogroups. The geographical origins and languages of the athletes and controls suggest that these differences are less likely to be a reflection of population structure and that Y chromosome haplogroups may play a significant role in determining Ethiopian endurance running success.

  11. Pre-exercise glycerol hydration improves cycling endurance time

    NASA Technical Reports Server (NTRS)

    Montner, P.; Stark, D. M.; Riedesel, M. L.; Murata, G.; Robergs, R.; Timms, M.; Chick, T. W.

    1996-01-01

    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.

  12. Physiological determinants of climbing-specific finger endurance and sport rock climbing performance.

    PubMed

    MacLeod, D; Sutherland, D L; Buntin, L; Whitaker, A; Aitchison, T; Watt, I; Bradley, J; Grant, S

    2007-10-01

    The aim of the study was to examine several physiological responses to a climbing-specific task to identify determinants of endurance in sport rock climbing. Finger strength and endurance of intermediate rock climbers (n = 11) and non-climbers (n = 9) were compared using climbing-specific apparatus. After maximum voluntary contraction (MVC) trials, two isometric endurance tests were performed at 40% (s = 2.5%) MVC until volitional exhaustion (continuous contractions and intermittent contractions of 10 s, with 3 s rest between contractions). Changes in muscle blood oxygenation and muscle blood volume were recorded in the flexor digitorum superficialis using near infra-red spectroscopy. Statistical significance was set at P < 0.05. Climbers had a higher mean MVC (climbers: 485 N, s = 65; non-climbers 375 N, s = 91) (P = 0.009). The group mean endurance test times were similar. The force-time integral, used as a measure of climbing-specific endurance, was greater for climbers in the intermittent test (climbers: 51,769 N x s, s = 12,229; non-climbers: 35,325 N x s, s = 9724) but not in the continuous test (climbers: 21,043 N x s, s = 4474; non-climbers: 15,816 N x s, s = 6263). Recovery of forearm oxygenation during rest phases (intermittent test) explained 41.1% of the variability in the force-time integral. Change in total haemoglobin was significantly greater in non-climbers (continuous test) than climbers (P = 0.023--40% test timepoint, P = 0.014--60% test timepoint). Pressor responses were similar between groups and not related to the force-time integral for either test. We conclude that muscle re-oxygenation during rest phases is a predictor of endurance performance.

  13. Anaerobic capacity, isometric endurance, and Laser sailing performance.

    PubMed

    Vangelakoudi, A; Vogiatzis, I; Geladas, N

    2007-08-01

    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

  14. Trunk muscle endurance and low back pain in female dance students.

    PubMed

    Swain, Christopher; Redding, Emma

    2014-01-01

    Low back pain (LBP) is often cited as a common condition at all levels of dance. Evidence suggests that reduced endurance of the trunk muscles can predispose an individual to LBP. The purpose of this study was to examine differences in trunk muscle endurance in a sample of tertiary level dance students with and without LBP. Seventeen full-time female dance students were divided into two groups: dance students with LBP (N = 11), and without LBP (N = 6). All participants provided informed consent, and the study was approved by an institutional ethics review board. Participants performed four isometric tests that assess trunk muscle endurance: the right and left side plank, double straight leg raise (DSLR), and the Sorensen test. A modified version of the Osaka City University test was used to assess the presence of LBP. A significant difference (p < 0.05) between groups was observed for the right and left side plank, as well as the DSLR test, and students with LBP displayed lower levels of endurance compared to those without. No other significant differences were found. This study offers some evidence that reduced trunk muscle endurance is present among dancers with LBP and provides direction for future research into back health among dancers.

  15. Endurance running and the evolution of Homo.

    PubMed

    Bramble, Dennis M; Lieberman, Daniel E

    2004-11-18

    Striding bipedalism is a key derived behaviour of hominids that possibly originated soon after the divergence of the chimpanzee and human lineages. Although bipedal gaits include walking and running, running is generally considered to have played no major role in human evolution because humans, like apes, are poor sprinters compared to most quadrupeds. Here we assess how well humans perform at sustained long-distance running, and review the physiological and anatomical bases of endurance running capabilities in humans and other mammals. Judged by several criteria, humans perform remarkably well at endurance running, thanks to a diverse array of features, many of which leave traces in the skeleton. The fossil evidence of these features suggests that endurance running is a derived capability of the genus Homo, originating about 2 million years ago, and may have been instrumental in the evolution of the human body form.

  16. Combined Strength and Endurance Training in Competitive Swimmers

    PubMed Central

    Aspenes, Stian; Kjendlie, Per-Ludvik; Hoff, Jan; Helgerud, Jan

    2009-01-01

    A combined intervention of strength and endurance training is common practice in elite swimming training, but the scientific evidence is scarce. The influences between strength and endurance training have been investigated in other sports but the findings are scattered. Some state the interventions are negative to each other, some state there is no negative relationship and some find bisected and supplementary benefits from the combination when training is applied appropriately. The aim of this study was to investigate the impact of a combined intervention among competitive swimmers. 20 subjects assigned to a training intervention group (n = 11) or a control group (n = 9) from two different teams completed the study. Anthropometrical data, tethered swimming force, land strength, performance in 50m, 100m and 400m, work economy, peak oxygen uptake, stroke length and stroke rate were investigated in all subjects at pre- and post-test. A combined intervention of maximal strength and high aerobic intensity interval endurance training 2 sessions per week over 11 weeks in addition to regular training were used, while the control group continued regular practice with their respective teams. The intervention group improved land strength, tethered swimming force and 400m freestyle performance more than the control group. The improvement of the 400m was correlated with the improvement of tethered swimming force in the female part of the intervention group. No change occurred in stroke length, stroke rate, performance in 50m or 100m, swimming economy or peak oxygen uptake during swimming. Two weekly dry-land strength training sessions for 11 weeks increase tethered swimming force in competitive swimmers. This increment further improves middle distance swimming performance. 2 weekly sessions of high- intensity interval training does not improve peak oxygen uptake compared with other competitive swimmers. Key points Two weekly sessions of dry land strength training improves the

  17. Sprint, agility, strength and endurance capacity in wheelchair basketball players

    PubMed Central

    Granados, C; Otero, M; Badiola, A; Olasagasti, J; Bidaurrazaga-Letona, I; Iturricastillo, A; Gil, SM

    2014-01-01

    The aims of the present study were, firstly, to determine the reliability and reproducibility of an agility T-test and Yo-Yo 10 m recovery test; and secondly, to analyse the physical characteristics measured by sprint, agility, strength and endurance field tests in wheelchair basketball (WB) players. 16 WB players (33.06 ± 7.36 years, 71.89 ± 21.71 kg and sitting body height 86.07 ± 6.82 cm) belonging to the national WB league participated in this study. Wheelchair sprint (5 and 20 m without ball, and 5 and 20 m with ball) agility (T-test and pick-up test) strength (handgrip and maximal pass) and endurance (Yo-Yo 10 m recovery test) were performed. T-test and Yo-Yo 10 m recovery test showed good reproducibility values (intraclass correlation coefficient, ICC = 0.74-0.94). The WB players’ results in 5 and 20 m sprints without a ball were 1.87 ± 0.21 s and 5.70 ± 0.43 s and with a ball 2.10 ± 0.30 s and 6.59 ± 0.61 s, being better than those reported in the literature. Regarding the pick-up test results (16.05 ± 0.52 s) and maximal pass (8.39 ± 1.77 m), players showed worse values than those obtained in elite players. The main contribution of the present study is the characterization of the physical performance profile of WB players using a field test battery. Furthermore, we demonstrated that the agility T-test and the aerobic Yo-Yo 10 m recovery test are reliable; consequently they may be appropriate instruments for measuring physical fitness in WB. PMID:25729153

  18. Effect of endurance training on lung function: a one year study

    PubMed Central

    Kippelen, P; Caillaud, C; Robert, E; Connes, P; Godard, P; Prefaut, C

    2005-01-01

    Objective: To identify in a follow up study airway changes occurring during the course of a sport season in healthy endurance athletes training in a Mediterranean region. Methods: Respiratory pattern and function were analysed in 13 healthy endurance trained athletes, either during a maximal exercise test, or at rest and during recovery through respiratory manoeuvres (spirometry and closing volume tests). The exercise test was conducted on three different occasions: during basic endurance training and then during the precompetition and competitive periods. Results: During the competitive period, a slight but non-clinically significant decrease was found in forced vital capacity (–3.5%, p = 0.0001) and an increase in slope of phase III (+25%, p = 0.0029), both at rest and after exercise. No concomitant reduction in expiratory flow rates was noticed. During maximal exercise there was a tachypnoeic shift over the course of the year (mean (SEM) breathing frequency and tidal volume were respectively 50 (2) cycles/min and 3.13 (0.09) litres during basic endurance training v 55 (3) cycles/min and 2.98 (0.10) litres during the competitive period; p<0.05). Conclusions: This study does not provide significant evidence of lung function impairment in healthy Mediterranean athletes after one year of endurance training. PMID:16118298

  19. Endurance of Undergraduate Attitudes toward Older Adults

    ERIC Educational Resources Information Center

    Funderburk, Brooke; Damron-Rodriguez, JoAnn; Storms, Lene Levy; Solomon, David H.

    2006-01-01

    This cross-sectional study assessed undergraduate attitudes toward older adults and attitude endurance 3 to 18 months after aging coursework. Survey respondents included 349 students who took an aging elective and 430 comparison students. Aging-elective students indicated more positive attitudes than comparison students. Attitudes did not vary…

  20. The Personal Meaning of Participation: Enduring Involvement.

    ERIC Educational Resources Information Center

    McIntyre, N.

    1989-01-01

    Examines the personal meaning of participation, discussing recreation and consumer behavior literature, the development of an instrument to measure the concept, and the relationship between commitment to camping and choice of campground setting. Personal meaning of participation seems to be best represented by the concept of enduring involvement.…

  1. Passion and Pacing in Endurance Performance

    PubMed Central

    Schiphof-Godart, Lieke; Hettinga, Florentina J.

    2017-01-01

    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

  2. Enduring Mental Health: Prevalence and Prediction

    PubMed Central

    2016-01-01

    We review epidemiological evidence indicating that most people will develop a diagnosable mental disorder, suggesting that only a minority experience enduring mental health. This minority has received little empirical study, leaving the prevalence and predictors of enduring mental health unknown. We turn to the population-representative Dunedin cohort, followed from birth to midlife, to compare people never-diagnosed with mental disorder (N = 171; 17% prevalence) to those diagnosed at 1–2 study waves, the cohort mode (N = 409). Surprisingly, compared to this modal group, never-diagnosed Study members were not born into unusually well-to-do families, nor did their enduring mental health follow markedly sound physical health, or unusually high intelligence. Instead, they tended to have an advantageous temperament/personality style, and negligible family history of mental disorder. As adults, they report superior educational and occupational attainment, greater life satisfaction, and higher-quality relationships. Our findings draw attention to “enduring mental health” as a revealing psychological phenotype and suggest it deserves further study. PMID:27929304

  3. Case Study: Operation Enduring Freedom Philippines

    DTIC Science & Technology

    2010-10-01

    Special Operations units worked with local authorities, host nation military and non- governmental agencies, to ensure unity of effort. Over time...relatively short time, the local population was made sufficiently comfortable with the host nation and US forces that they began to provide useful...Enduring Freedom Philippines 4 local communities by the terrorist group, highlighted by friendly psychological operations, probably facilitated the

  4. The combined impact of metabolic gene polymorphisms on elite endurance athlete status and related phenotypes.

    PubMed

    Ahmetov, Ildus I; Williams, Alun G; Popov, Daniil V; Lyubaeva, Ekaterina V; Hakimullina, Albina M; Fedotovskaya, Olga N; Mozhayskaya, Irina A; Vinogradova, Olga L; Astratenkova, Irina V; Montgomery, Hugh E; Rogozkin, Viktor A

    2009-12-01

    Endurance performance is a complex phenotype subject to the influence of both environmental and genetic factors. Although the last decade has seen a variety of specific genetic factors proposed, many in metabolic pathways, each is likely to make a limited contribution to an 'elite' phenotype: it seems more likely that such status depends on the simultaneous presence of multiple such variants. The aim of the study was to investigate individually and in combination the association of common metabolic gene polymorphisms with endurance athlete status, the proportion of slow-twitch muscle fibers and maximal oxygen consumption. A total of 1,423 Russian athletes and 1,132 controls were genotyped for 15 gene polymorphisms, of which most were previously reported to be associated with athlete status or related intermediate phenotypes. Muscle fiber composition of m. vastus lateralis in 45 healthy men was determined by immunohistochemistry. Maximal oxygen consumption of 50 male rowers of national competitive standard was determined during an incremental test to exhaustion on a rowing ergometer. Ten 'endurance alleles' (NFATC4 Gly160, PPARA rs4253778 G, PPARD rs2016520 C, PPARGC1A Gly482, PPARGC1B 203Pro, PPP3R1 promoter 5I, TFAM 12Thr, UCP2 55Val, UCP3 rs1800849 T and VEGFA rs2010963 C) were first identified showing discrete associations with elite endurance athlete status. Next, to assess the combined impact of all 10 gene polymorphisms, all athletes were classified according to the number of 'endurance' alleles they possessed. The proportion of subjects with a high (≥9) number of 'endurance' alleles was greater in the best endurance athletes compared with controls (85.7 vs. 37.8%, P = 7.6 × 10(-6)). The number of 'endurance' alleles was shown to be positively correlated (r = 0.50; P = 4.0 × 10(-4)) with the proportion of fatigue-resistant slow-twitch fibers, and with maximal oxygen consumption (r = 0.46; P = 7.0 × 10(-4)). These data suggest that the likelihood of

  5. Factors limiting endurance of armor, artillery, and infantry units under simulated NBC conditions

    SciTech Connect

    Rauch, T.M.; Tharion, W.J.; Banderet, L.E.; Lussier, A.R.

    1986-03-13

    The war of the future will require 72-hour operations in environments contaminated with nuclear/biological/chemical (NBC) agents. The 1985 P2NBC2 (Physiological and Psychological Effects of NBC and Extended Operations on Combined Arms Crews) Program assessed soldier endurance and performance under simulated NBC conditions. A total of 175 soldiers were observed during four tests differing in design, site, climatic conditions, and performance demands. In all but one of the iterations where the full chemical-protective ensemble (MOPP 4) was used without cooling, soldier endurance fell far short of the projected requirement. Psychological data were analyzed to determine which factors were associated with the incidence of casualties. The findings showed that perceived intensity of symptoms resembling the hyperventilation syndrome was significantly greater in soldiers classified as Casualties. Five of these symptoms (painful breathing, difficulty breathing, shortness of breath, headache, and nausea) showed Casualty-Survivor differences in all tests. Symptom intensity was attributed to two factors. (1) External conditions. Thermal stress exacerbated the five basic symptoms, induced others (tetany and paresthesia), and decreased endurance. Periodic relief from respirator use attenuated these symptoms and enhanced endurance. (2) Individual differences. Significant Casualty-Survivor differences in anxiety, depression, and cognitive strategy scores indicated that perception of hyperventilation symptoms and endurance were related to personality variables. Hyperventilation symptoms could incapacitate the soldier or induce removal of the protective mask under actual chemical attack.

  6. Salmonella spp. fecal shedding detected by real-time PCR in competing endurance horses.

    PubMed

    Fielding, C Langdon; Meier, Chloe A; Magdesian, K Gary; Pusterla, Nicola

    2013-09-01

    Fecal shedding of Salmonella spp. was recently documented in 8% of endurance horses presented to equine referral centers for colic. Previous studies have documented fecal shedding of Salmonella spp. in as few as 0.8% of the general horse population, although horses with colic appear to be at higher risk. Fecal Salmonella spp. shedding before and after endurance horse competitions has not been evaluated. Fecal samples were collected from 204 horses during three separate 100 mile endurance competitions. Following incubation in selenite broth, 289 fecal samples were tested by real-time PCR analysis for Salmonella spp. Only one post-race sample (0.5% tested positive for Salmonella spp. in this study and no pre-race sample was available from this horse. Results suggest that fecal shedding of Salmonella spp. is uncommon in endurance horses during competitions. Further research is needed to confirm and identify the source of Salmonella spp. infection in endurance horses with colic requiring treatment at referral centers.

  7. Nuclear materials stewardship: Our enduring mission

    SciTech Connect

    Isaacs, T.H.

    1998-12-31

    The US Department of Energy (DOE) and its predecessors have handled a remarkably wide variety of nuclear materials over the past 50 yr. Two fundamental changes have occurred that shape the current landscape regarding nuclear materials. If one recognizes the implications and opportunities, one sees that the stewardship of nuclear materials will be a fundamental and important job of the DOE for the foreseeable future. The first change--the breakup of the Soviet Union and the resulting end to the nuclear arms race--altered US objectives. Previously, the focus was on materials production, weapon design, nuclear testing, and stockpile enhancements. Now the attention is on dismantlement of weapons, excess special nuclear material inventories, accompanying increased concern over the protection afforded to such materials; new arms control measures; and importantly, maintenance of the safety and reliability of the remaining arsenal without testing. The second change was the raised consciousness and sense of responsibility for dealing with the environmental legacies of past nuclear arms programs. Recognition of the need to clean up radioactive contamination, manage the wastes, conduct current operations responsibly, and restore the environment have led to the establishment of what is now the largest program in the DOE. Two additional features add to the challenge and drive the need for recognition of nuclear materials stewardship as a fundamental, enduring, and compelling mission of the DOE. The first is the extraordinary time frames. No matter what the future of nuclear weapons and no matter what the future of nuclear power, the DOE will be responsible for most of the country`s nuclear materials and wastes for generations. Even if the Yucca Mountain program is successful and on schedule, it will last more than 100 yr. Second, the use, management, and disposition of nuclear materials and wastes affect a variety of nationally important and diverse objectives, from national

  8. Rapid Response Research and Development (R&D) for the Aerospace Systems Directorate. Delivery Order 0021: Engineering Research and Technical Analyses of Advanced Airbreathing Propulsion Fuels, Subtask: T700 Biofuel Low Lubricity Endurance

    DTIC Science & Technology

    2014-09-01

    Engineering Research and Technical Analyses of Advanced Airbreathing Propulsion Fuels Subtask: T700 Biofuel Low Lubricity Endurance Jeff Sympson...Subtask: T700 Biofuel Low Lubricity Endurance 5a. CONTRACT NUMBER FA8650-08-D-2806-0021 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 63216F 6... biofuel low lubricity endurance test. The testing was performed on Woodward Item Number 6970-034 according to Woodward test procedure DTP-1827 Rev

  9. Validity of Field Tests of Upper Body Muscular Strength.

    ERIC Educational Resources Information Center

    Pate, Russell, R; And Others

    1993-01-01

    Examined the validity of field tests of elementary students' upper body muscular strength and endurance. Field tests were found to be moderately valid measures of weight-relative muscular strength but not of absolute strength and muscular endurance. (SM)

  10. LOWER EXTREMITY HYPERMOBILITY, BUT NOT CORE MUSCLE ENDURANCE INFLUENCES BALANCE IN FEMALE COLLEGIATE DANCERS

    PubMed Central

    Cortes, Nelson; Caswell, Shane V.; Ambegaonkar, Gautam P.; Wyon, Matthew

    2016-01-01

    Background Dance is a physically demanding activity, with almost 70% of all injuries in dancers occurring in the lower extremity (LE). Prior researchers report that muscle function (e.g. muscle endurance) and anatomical factors (e.g. hypermobility) affect physical performance (e.g. balance) and can subsequently influence LE injury risk. Specifically, lesser core muscle endurance, balance deficits, and greater hypermobility are related to increased LE injury risk. However, the potentials interrelationships among these factors in dancers remain unclear. Purpose The purposes of this study were to examine the relationships among core muscle endurance, balance, and LE hypermobility, and determine the relative contributions of core muscle endurance and LE hypermobility as predictors of balance in female collegiate dancers. Study Design Cross-sectional Methods Core muscle endurance was evaluated using the combined average anterior, left, and right lateral plank test time scores(s). LE hypermobility was measured using the LE-specific Beighton hypermobility measure, defining hypermobility if both legs had greater than 10 ° knee hyperextension. Balance was measured via the composite anterior, posterolateral, and posteromedial Star Excursion Balance Test (SEBT) reach distances (normalized to leg length) in 15 female healthy collegiate dancers (18.3 + 0.5yrs, 165.5 + 6.9cm, 63.7 + 12.1kg). Point-biserial-correlation-coefficients examined relationships and a linear regression examined whether core endurance and hypermobility predicted balance (p<.05). Results LE hypermobility (Yes; n = 3, No; n = 12) and balance (87.2 + 8.3% leg length) were positively correlated r(14)=.67, (p=.01). However, core endurance (103.9 + 50.6 s) and balance were not correlated r(14)=.32, (p=.26). LE hypermobility status predicted 36.9% of the variance in balance scores (p=.01). Conclusion LE hypermobility, but not core muscle endurance may be related to balance in female

  11. Concurrent training in elite male runners: the influence of strength versus muscular endurance training on performance outcomes.

    PubMed

    Sedano, Silvia; Marín, Pedro J; Cuadrado, Gonzalo; Redondo, Juan C

    2013-09-01

    Much recent attention has been given to the compatibility of combined aerobic and anaerobic training modalities. However, few of these studies have reported data related to well-trained runners, which is a potential limitation. Therefore, because of the limited evidence available for this population, the main aim was to determine which mode of concurrent strength-endurance training might be the most effective at improving running performance in highly trained runners. Eighteen well-trained male runners (age 23.7 ± 1.2 years) with a maximal oxygen consumption (VO2max) more than 65 ml·kg(-1)·min(-1) were randomly assigned into 1 of the 3 groups: Endurance-only Group (n = 6), who continued their usual training, which included general strength training with Thera-band latex-free exercise bands and endurance training; Strength Group (SG; n = 6) who performed combined resistance and plyometric exercises and endurance training; Endurance-SG (ESG; n = 6) who performed endurance-strength training with loads of 40% and endurance training. The study comprised 12 weeks of training in which runners trained 8 times a week (6 endurance and 2 strength sessions) and 5 weeks of detraining. The subjects were tested on 3 different occasions (countermovement jump height, hopping test average height, 1 repetition maximum, running economy (RE), VO2max, maximal heart rate [HRmax], peak velocity (PV), rating of perceived exertion, and 3-km time trial were measured). Findings revealed significant time × group interaction effects for almost all tests (p < 0.05). We can conclude that concurrent training for both SG and ESG groups led to improved maximal strength, RE, and PV with no significant effects on the VO2 kinetics pattern. The SG group also seems to show improvements in 3-km time trial tests.

  12. Correlation between Quadriceps Endurance and Adduction Moment in Medial Knee Osteoarthritis

    PubMed Central

    Ahn, Sung-Eun; Park, Min-Ji; Lee, Dae-Hee

    2015-01-01

    It is not clear whether the strength or endurance of thigh muscles (quadriceps and hamstring) is positively or negatively correlated with the adduction moment of osteoarthritic knees. This study therefore assessed the relationships between the strength and endurance of the quadriceps and hamstring muscles and adduction moment in osteoarthritic knees and evaluated predictors of the adduction moment. The study cohort comprised 35 patients with unilateral medial osteoarthritis and varus deformity who were candidates for open wedge osteotomy. The maximal torque (60°/sec) and total work (180°/sec) of the quadriceps and hamstring muscles and knee adduction moment were evaluated using an isokinetic testing device and gait analysis system. The total work of the quadriceps (r = 0.429, P = 0.037) and hamstring (r = 0.426, P = 0.045) muscles at 180°/sec each correlated with knee adduction moment. Preoperative varus deformity was positively correlated with adduction moment (r = 0.421, P = 0.041). Multiple linear regression analysis showed that quadriceps endurance at 180°/sec was the only factor independently associated with adduction moment (β = 0.790, P = 0.032). The adduction moment of osteoarthritic knees correlated with the endurance, but not the strength, of the quadriceps muscle. However, knee adduction moment did not correlate with the strength or endurance of the hamstring muscle. PMID:26539830

  13. Durability testing at 5 atmospheres of advanced catalysts and catalyst supports for gas turbine engine combustors

    NASA Technical Reports Server (NTRS)

    Olson, B. A.; Lee, H. C.; Osgerby, I. T.; Heck, R. M.; Hess, H.

    1980-01-01

    The durability of CATCOM catalysts and catalyst supports was experimentally demonstrated in a combustion environment under simulated gas turbine engine combustor operating conditions. A test of 1000 hours duration was completed with one catalyst using no. 2 diesel fuel and operating at catalytically-supported thermal combustion conditions. The performance of the catalyst was determined by monitoring emissions throughout the test, and by examining the physical condition of the catalyst core at the conclusion of the test. Tests were performed periodically to determine changes in catalytic activity of the catalyst core. Detailed parametric studies were also run at the beginning and end of the durability test, using no. 2 fuel oil. Initial and final emissions for the 1000 hours test respectively were: unburned hydrocarbons (C3 vppm):0, 146, carbon monoxide (vppm):30, 2420; nitrogen oxides (vppm):5.7, 5.6.

  14. Myocardial fibrosis in an veteran endurance athlete

    PubMed Central

    Wilson, Mathew; O'Hanlon, Rory; Prasad, Sanjay; Basavarajaiah, Sandeep; Stephens, Nigel; Senior, Roxy; Shaw, Anthony; Sharma, Sanjay; Whyte, Gregory

    2009-01-01

    This study reports the cardiac structure and function of a lifelong male endurance athlete, who has run over 148 000 miles, who presented with symptoms of chest discomfort, dyspnoea and loss of competitive running performance. Importantly, the athlete documented several periods of regular intensive endurance activity while suffering with flu-like symptoms. Cardiovascular MRI demonstrated a pattern of late gadolinium enhancement, which indicated myocardial scarring as a result of previous myocarditis. Myocarditis is a non-ischaemic inflammatory disease of the myocardium associated with cardiac dysfunction and arrhythmogenic substrate. The clinical course of viral myocarditis is mostly insidious with limited cardiac inflammation and dysfunction. However, as in the present case, overwhelming inflammation may occur in a subset of patients leading to myocardial fibrosis due to recurrent inflammation. PMID:21847425

  15. Environmental testing of CIS based modules

    SciTech Connect

    Willett, D.

    1995-11-01

    This report describes environmental testing of Siemen`s CIS modules. Charts and diagrams are presented on data concerning: temporary power loss of laminated mini-modules; the 50 thermal cycle test; the 10 humidity freeze cycle test; results after 1000 hours of exposure to damp heat; and interconnect test structures in damp heat testing. It is concluded that moisture ingress causes permanent increases in the series resistance of modules, and that improved packaging is needed for better high humidity reliability. Also, dry dark heat caused temporary power losses which were recovered in sunlight.

  16. New records in aerobic power among octogenarian lifelong endurance athletes

    PubMed Central

    Hayes, Erik; Galpin, Andrew; Kaminsky, Leonard; Jemiolo, Bozena; Fink, William; Trappe, Todd; Jansson, Anna; Gustafsson, Thomas; Tesch, Per

    2013-01-01

    We examined whole body aerobic capacity and myocellular markers of oxidative metabolism in lifelong endurance athletes [n = 9, 81 ± 1 yr, 68 ± 3 kg, body mass index (BMI) = 23 ± 1 kg/m2] and age-matched, healthy, untrained men (n = 6; 82 ± 1 y, 77 ± 5 kg, BMI = 26 ± 1 kg/m2). The endurance athletes were cross-country skiers, including a former Olympic champion and several national/regional champions, with a history of aerobic exercise and participation in endurance events throughout their lives. Each subject performed a maximal cycle test to assess aerobic capacity (V̇o2max). Subjects had a resting vastus lateralis muscle biopsy to assess oxidative enzymes (citrate synthase and βHAD) and molecular (mRNA) targets associated with mitochondrial biogenesis [peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and mitochondrial transcription factor A (Tfam)]. The octogenarian athletes had a higher (P < 0.05) absolute (2.6 ± 0.1 vs. 1.6 ± 0.1 l/min) and relative (38 ± 1 vs. 21 ± 1 ml·kg−1·min−1) V̇o2max, ventilation (79 ± 3 vs. 64 ± 7 l/min), heart rate (160 ± 5 vs. 146 ± 8 beats per minute), and final workload (182 ± 4 vs. 131 ± 14 W). Skeletal muscle oxidative enzymes were 54% (citrate synthase) and 42% (βHAD) higher (P < 0.05) in the octogenarian athletes. Likewise, basal PGC-1α and Tfam mRNA were 135% and 80% greater (P < 0.05) in the octogenarian athletes. To our knowledge, the V̇o2max of the lifelong endurance athletes is the highest recorded in humans >80 yr of age and comparable to nonendurance trained men 40 years younger. The superior cardiovascular and skeletal muscle health profile of the octogenarian athletes provides a large functional reserve above the aerobic frailty threshold and is associated with lower risk for disability and mortality. PMID:23065759

  17. New records in aerobic power among octogenarian lifelong endurance athletes.

    PubMed

    Trappe, Scott; Hayes, Erik; Galpin, Andrew; Kaminsky, Leonard; Jemiolo, Bozena; Fink, William; Trappe, Todd; Jansson, Anna; Gustafsson, Thomas; Tesch, Per

    2013-01-01

    We examined whole body aerobic capacity and myocellular markers of oxidative metabolism in lifelong endurance athletes [n = 9, 81 ± 1 yr, 68 ± 3 kg, body mass index (BMI) = 23 ± 1 kg/m(2)] and age-matched, healthy, untrained men (n = 6; 82 ± 1 y, 77 ± 5 kg, BMI = 26 ± 1 kg/m(2)). The endurance athletes were cross-country skiers, including a former Olympic champion and several national/regional champions, with a history of aerobic exercise and participation in endurance events throughout their lives. Each subject performed a maximal cycle test to assess aerobic capacity (VO(2max)). Subjects had a resting vastus lateralis muscle biopsy to assess oxidative enzymes (citrate synthase and βHAD) and molecular (mRNA) targets associated with mitochondrial biogenesis [peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) and mitochondrial transcription factor A (Tfam)]. The octogenarian athletes had a higher (P < 0.05) absolute (2.6 ± 0.1 vs. 1.6 ± 0.1 l/min) and relative (38 ± 1 vs. 21 ± 1 ml·kg(-1)·min(-1)) VO(2max), ventilation (79 ± 3 vs. 64 ± 7 l/min), heart rate (160 ± 5 vs. 146 ± 8 beats per minute), and final workload (182 ± 4 vs. 131 ± 14 W). Skeletal muscle oxidative enzymes were 54% (citrate synthase) and 42% (βHAD) higher (P < 0.05) in the octogenarian athletes. Likewise, basal PGC-1α and Tfam mRNA were 135% and 80% greater (P < 0.05) in the octogenarian athletes. To our knowledge, the VO(2max) of the lifelong endurance athletes is the highest recorded in humans >80 yr of age and comparable to nonendurance trained men 40 years younger. The superior cardiovascular and skeletal muscle health profile of the octogenarian athletes provides a large functional reserve above the aerobic frailty threshold and is associated with lower risk for disability and mortality.

  18. Relationship between laboratory-measured variables and heart rate during an ultra-endurance triathlon.

    PubMed

    Laursen, Paul B; Knez, Wade L; Shing, Cecilia M; Langill, Robert H; Rhodes, Edward C; Jenkins, David G

    2005-10-01

    The aim of the present study was to examine the relationship between the performance heart rate during an ultra-endurance triathlon and the heart rate corresponding to several demarcation points measured during laboratory-based progressive cycle ergometry and treadmill running. Less than one month before an ultra-endurance triathlon, 21 well-trained ultra-endurance triathletes (mean +/- s: age 35 +/- 6 years, height 1.77 +/- 0.05 m, mass 74.0 +/- 6.9 kg, = 4.75 +/- 0.42 l x min(-1)) performed progressive exercise tests of cycle ergometry and treadmill running for the determination of peak oxygen uptake (VO2peak), heart rate corresponding to the first and second ventilatory thresholds, as well as the heart rate deflection point. Portable telemetry units recorded heart rate at 60 s increments throughout the ultra-endurance triathlon. Heart rate during the cycle and run phases of the ultra-endurance triathlon (148 +/- 9 and 143 +/- 13 beats x min(-1) respectively) were significantly (P < 0.05) less than the second ventilatory thresholds (160 +/- 13 and 165 +/- 14 beats x min(-1) respectively) and heart rate deflection points (170 +/- 13 and 179 +/- 9 beats x min(-1) respectively). However, mean heart rate during the cycle and run phases of the ultra-endurance triathlon were significantly related to (r = 0.76 and 0.66; P < 0.01), and not significantly different from, the first ventilatory thresholds (146 +/- 12 and 148 +/- 15 beats x min(-1) respectively). Furthermore, the difference between heart rate during the cycle phase of the ultra-endurance triathlon and heart rate at the first ventilatory threshold was related to marathon run time (r = 0.61; P < 0.01) and overall ultra-endurance triathlon time (r = 0.45; P < 0.05). The results suggest that triathletes perform the cycle and run phases of the ultra-endurance triathlon at an exercise intensity near their first ventilatory threshold.

  19. Arctigenin efficiently enhanced sedentary mice treadmill endurance.

    PubMed

    Tang, Xuan; Zhuang, Jingjing; Chen, Jing; Yu, Liang; Hu, Lihong; Jiang, Hualiang; Shen, Xu

    2011-01-01

    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.

  20. Effect of caffeine on sport-specific endurance performance: a systematic review.

    PubMed

    Ganio, Matthew S; Klau, Jennifer F; Casa, Douglas J; Armstrong, Lawrence E; Maresh, Carl M

    2009-01-01

    Endurance athletes often ingest caffeine because of its reported ergogenic properties. Although there are a vast number of studies quantifying caffeine's effects, many research studies measure endurance performance using a time-to-exhaustion test (subjects exercise at a fixed intensity to volitional exhaustion). Time-to-exhaustion as a performance measure is not ideal because of the high degree of measurement variability between and within subjects. Also, we are unaware of any endurance sports in which individuals win by going a longer distance or for a longer amount of time than their competitors. Measuring performance with a time-trial test (set distance or time with best effort) has high reproducibility and is more applicable to sport. Therefore, the purpose of this review was to critically and objectively evaluate studies that have examined the effect of caffeine on time-trial endurance (>5 minutes) performance. A literature search revealed 21 studies with a total of 33 identifiable caffeine treatments that measured endurance performance with a time-trial component. Each study was objectively analyzed with the Physiotherapy Evidence Database (PEDro) scale. The mean PEDro rating was 9.3 out of 10, indicating a high quality of research in this topic area. The mean improvement in performance with caffeine ingestion was 3.2 +/- 4.3%; however, this improvement was highly variable between studies (-0.3 to 17.3%). The high degree of variability may be dependent on a number of factors including ingestion timing, ingestion mode/vehicle, and subject habituation. Further research should seek to identify individual factors that mediate the large range of improvements observed with caffeine ingestion. In conclusion, caffeine ingestion can be an effective ergogenic aid for endurance athletes when taken before and/or during exercise in moderate quantities (3-6 mg.kg body mass). Abstaining from caffeine at least 7 days before use will give the greatest chance of optimizing the

  1. Comparison between two types of anaerobic speed endurance training in competitive soccer players

    PubMed Central

    Krustrup, Peter

    2016-01-01

    Abstract The purpose of the present study was to examine the effects of additional in-season speed endurance production versus speed endurance maintenance training regimes on performance in competitive male soccer players. In a randomised controlled trial 18 male sub-elite players were exposed to additional speed endurance production (SEP) or speed endurance maintenance (SEM) training (two additional sessions/wk for 4 weeks) during the competitive season. Players performed the Yo-Yo intermittent recovery level 2 test (YYIR2) and a repeated sprint test (RST) pre- and post-intervention. Yo-Yo IR2 performance increased (p<0.001) by 50 ± 8% and 26 ± 5% in SEP and SEM, respectively, with greater (p=0.03) improvement in SEP. RST performance improved by 2.1 ± 0.3% and 1.3 ± 0.4% in SEP and SEM, respectively, while the RST fatigue index decreased (4.4 ± 0.8 to 3.4 ± 0.5%; p<0.04) in SEP only. Peak and average speed during training were higher (p<0.001) in SEP than in SEM (24.5 ± 0.3 vs 19.2 ± 0.3 and 15.5 ± 0.1 km·h-1 vs 9.4 ± 0.1 km·h-1). Additional in-season anaerobic speed endurance production and maintenance training improves high-intensity exercise performance in competitive soccer players with superior effects of speed endurance production training. PMID:28149381

  2. Strength training prior to endurance exercise: impact on the neuromuscular system, endurance performance and cardiorespiratory responses.

    PubMed

    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

    2014-12-09

    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.

  3. Enduring voice recognition in bonobos

    PubMed Central

    Keenan, Sumir; Mathevon, Nicolas; Stevens, Jeroen MG; Guéry, Jean Pascal; Zuberbühler, Klaus; Levréro, Florence

    2016-01-01

    Long-term social recognition is vital for species with complex social networks, where familiar individuals can encounter one another after long periods of separation. For non-human primates who live in dense forest environments, visual access to one another is often limited, and recognition of social partners over distances largely depends on vocal communication. Vocal recognition after years of separation has never been reported in any great ape species, despite their complex societies and advanced social intelligence. Here we show that bonobos, Pan paniscus, demonstrate reliable vocal recognition of social partners, even if they have been separated for five years. We experimentally tested bonobos’ responses to the calls of previous group members that had been transferred between captive groups. Despite long separations, subjects responded more intensely to familiar voices than to calls from unknown individuals - the first experimental evidence that bonobos can identify individuals utilising vocalisations even years after their last encounter. Our study also suggests that bonobos may cease to discriminate between familiar and unfamiliar individuals after a period of eight years, indicating that voice representations or interest could be limited in time in this species. PMID:26911199

  4. Enduring voice recognition in bonobos.

    PubMed

    Keenan, Sumir; Mathevon, Nicolas; Stevens, Jeroen M G; Guéry, Jean Pascal; Zuberbühler, Klaus; Levréro, Florence

    2016-02-25

    Long-term social recognition is vital for species with complex social networks, where familiar individuals can encounter one another after long periods of separation. For non-human primates who live in dense forest environments, visual access to one another is often limited, and recognition of social partners over distances largely depends on vocal communication. Vocal recognition after years of separation has never been reported in any great ape species, despite their complex societies and advanced social intelligence. Here we show that bonobos, Pan paniscus, demonstrate reliable vocal recognition of social partners, even if they have been separated for five years. We experimentally tested bonobos' responses to the calls of previous group members that had been transferred between captive groups. Despite long separations, subjects responded more intensely to familiar voices than to calls from unknown individuals - the first experimental evidence that bonobos can identify individuals utilising vocalisations even years after their last encounter. Our study also suggests that bonobos may cease to discriminate between familiar and unfamiliar individuals after a period of eight years, indicating that voice representations or interest could be limited in time in this species.

  5. Antarctic crabs: invasion or endurance?

    PubMed

    Griffiths, Huw J; Whittle, Rowan J; Roberts, Stephen J; Belchier, Mark; Linse, Katrin

    2013-01-01

    Recent scientific interest following the "discovery" of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. This "invasion hypothesis" suggests that decapod crabs were driven out of Antarctica 40-15 million years ago and are only now returning as "warm" enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura), and examination of relatively few Recent lithodid samples from the Antarctic slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60 °S. All are restricted to waters warmer than 0 °C, with their Antarctic distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW). Currently, CDW extends further and shallower onto the West Antarctic shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day "crab invasion". We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the "invasion hypothesis".

  6. Antarctic Crabs: Invasion or Endurance?

    PubMed Central

    Griffiths, Huw J.; Whittle, Rowan J.; Roberts, Stephen J.; Belchier, Mark; Linse, Katrin

    2013-01-01

    Recent scientific interest following the “discovery” of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. This “invasion hypothesis” suggests that decapod crabs were driven out of Antarctica 40–15 million years ago and are only now returning as “warm” enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura), and examination of relatively few Recent lithodid samples from the Antarctic slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60°S. All are restricted to waters warmer than 0°C, with their Antarctic distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW). Currently, CDW extends further and shallower onto the West Antarctic shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day “crab invasion”. We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the

  7. Effect of endurance training on gross energy expenditure during exercise.

    PubMed

    Gardner, A W; Poehlman, E T; Corrigan, D L

    1989-08-01

    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.

  8. Respiratory muscle endurance, oxygen saturation index in vastus lateralis and performance during heavy exercise.

    PubMed

    Oueslati, Ferid; Boone, Jan; Ahmaidi, Said

    2016-06-15

    The purpose of this study was to investigate the relationships between respiratory muscle endurance, tissue oxygen saturation index dynamics of leg muscle (TSI) and the time to exhaustion (TTE) during high intensity exercise. Eleven males performed a respiratory muscle endurance test, a maximal incremental running field test (8 km h(-1)+0.5 km h(-1) each 60s) and a high-intensity constant speed field test at 90% VO2max. The TSI in vastus lateralis was monitored with near-infrared spectroscopy. The TSI remained steady between 20 and 80% of TTE. Between 80 and 100% of TTE (7.5 ± 6.1%, p<0.05), a significant drop in TSI concomitant with a minute ventilation increase (16 ± 10 l min(-1)) was observed. Moreover, the increase of ventilation was correlated to the drop in TSI (r=0.70, p<0.05). Additionally, respiratory muscle endurance was significantly correlated to TSI time plateau (20-80% TTE) (r=0.83, p<0.05) and to TTE (r=0.95, p<0.001). The results of the present study show that the tissue oxygen saturation plateau might be affected by ventilatory work and that respiratory muscle endurance could be considered as a determinant of performance during heavy exercise.

  9. Swimming endurance of bull trout, lake trout, arctic char, and rainbow trout following challenge with Renibacterium salmoninarum

    USGS Publications Warehouse

    Jones, D.T.; Moffitt, C.M.

    2004-01-01

    We tested the swimming endurance of juvenile bull trout Salvelinus confluentus, lake trout S. namaycush, Arctic char S. alpinus, and rainbow trout Oncorhynchus mykiss at 9??C and 15??C to determine whether sublethal infection from a moderate challenge of Renibacterium salmoninarum administered months before testing affected the length of time fish could maintain a swimming speed of 5-6 body lengths per second in an experimental flume. Rainbow trout and Arctic char swam longer in trials than did bull trout or lake trout, regardless of challenge treatment. When we tested fish 14-23 weeks postchallenge, we found no measurable effect of R. salmoninarum on the swimming endurance of the study species except for bull trout, which showed a mixed response. We conducted additional trials with bull trout 5-8 weeks postchallenge to determine whether increasing the challenge dose would affect swimming endurance and hematocrit. In those tests, bull trout with clinical signs of disease and those exposed to the highest challenge doses had significantly reduced swimming endurance compared with unchallenged control fish. Fish hematocrit levels measured at the end of all swimming endurance tests varied among species and between test temperatures, and patterns were not always consistent between challenged and control fish.

  10. Effects of a supplement designed to increase ATP levels on muscle strength, power output, and endurance

    PubMed Central

    Herda, Trent J; Ryan, Eric D; Stout, Jeffrey R; Cramer, Joel T

    2008-01-01

    Background The present study examined the acute effects of a nutritional supplement intended to improve adenosine triphosphate (ATP) concentrations on vertical jump height, isometric strength of the leg extensors, leg extension endurance, and forearm flexion endurance. Methods Twenty-four healthy men (mean age ± SD = 23 ± 4 yrs, stature = 181 ± 7 cm, and body mass = 82 ± 12 kg) volunteered to complete a familiarization trial plus 2 randomly-ordered experimental trials separated by a 7-day washout period. Participants received either 6 (body mass < 91 kg) or 8 (body mass ≥ 91 kg) tablets of the treatment (TR; 625 mg of adenylpyrophosphoric acid and calcium pyruvate, 350.8 mg of cordyceps sinensis extract and yohimbine hydrochloride) or placebo (PL; 980 mg of microcrystalline cellulose) 1 hour prior to the following tests: countermovement vertical jump (CVJ), forearm flexion repetitions to exhaustion, isometric maximal voluntary contractions (MVCs) of the leg extensors, and a 50-repetition maximal concentric isokinetic leg extension endurance test. Results There were no differences between the TR and PL trials for CVJ height (P > 0.05), isometric MVC peak torque (P > 0.05), maximal concentric isokinetic peak torque (P > 0.05), percent decline during the leg extension endurance tests (P > 0.05), or repetitions to exhaustion during the forearm flexion endurance tests (P > 0.05). Conclusion These findings indicated no improvements in the measured variables as a result of ingesting this nutritional supplement. Future studies should examine whether chronic supplementation or a loading period is necessary to observe any ergogenic effects of this supplement. PMID:18230170

  11. Different endurance characteristics of female and male german soccer players.

    PubMed

    Baumgart, C; Hoppe, M W; Freiwald, J

    2014-08-01

    The aims of the present study were to assess gender differences regarding lactate threshold and intermittent shuttle run performance in female and male soccer players as well as to investigate the relationships between both endurance characteristics in both genders. Fourteen female (1(st) division) and thirteen male (4(th) division) soccer players completed an incremental test (IT) to determine running velocities at 2 and 4 mmol · l(-1) blood lactate (v2 and v4) and maximum velocity (vmax) as well as an interval shuttle run test (ISRT) to determine running distance. Based on v2 and v4 and their percentages in relation to vmax, three intensity zones were calculated: a low lactate zone (v4). Female soccer players have a lower v4 (8.2%), vmax (11.3%) and ISRT distance (31.6%). No gender difference was found in v2. In contrast to males, ISRT distance correlates with vmax as well as with v2 and v4 in female soccer players. The intensity zones v4 differ between genders. The present study revealed that gender differences increase when the running performance is intermittent including change of directions. In both genders, different relationships between lactate threshold and intermittent shuttle run performance exist. During incremental testing, the running performances of female and male players reflect different distributions of aerobic and anaerobic metabolic pathways. The revealed gender differences should be considered for soccer endurance training.

  12. DIFFERENT ENDURANCE CHARACTERISTICS OF FEMALE AND MALE GERMAN SOCCER PLAYERS

    PubMed Central

    Hoppe, M.W.; Freiwald, J.

    2014-01-01

    The aims of the present study were to assess gender differences regarding lactate threshold and intermittent shuttle run performance in female and male soccer players as well as to investigate the relationships between both endurance characteristics in both genders. Fourteen female (1st division) and thirteen male (4th division) soccer players completed an incremental test (IT) to determine running velocities at 2 and 4 mmol · l−1 blood lactate (v2 and v4) and maximum velocity (vmax) as well as an interval shuttle run test (ISRT) to determine running distance. Based on v2 and v4 and their percentages in relation to vmax, three intensity zones were calculated: a low lactate zone (v4). Female soccer players have a lower v4 (8.2%), vmax (11.3%) and ISRT distance (31.6%). No gender difference was found in v2. In contrast to males, ISRT distance correlates with vmax as well as with v2 and v4 in female soccer players. The intensity zones v4 differ between genders. The present study revealed that gender differences increase when the running performance is intermittent including change of directions. In both genders, different relationships between lactate threshold and intermittent shuttle run performance exist. During incremental testing, the running performances of female and male players reflect different distributions of aerobic and anaerobic metabolic pathways. The revealed gender differences should be considered for soccer endurance training. PMID:25177102

  13. Limitations of Reliability for Long-Endurance Human Spaceflight

    NASA Technical Reports Server (NTRS)

    Owens, Andrew C.; de Weck, Olivier L.

    2016-01-01

    Long-endurance human spaceflight - such as missions to Mars or its moons - will present a never-before-seen maintenance logistics challenge. Crews will be in space for longer and be farther way from Earth than ever before. Resupply and abort options will be heavily constrained, and will have timescales much longer than current and past experience. Spare parts and/or redundant systems will have to be included to reduce risk. However, the high cost of transportation means that this risk reduction must be achieved while also minimizing mass. The concept of increasing system and component reliability is commonly discussed as a means to reduce risk and mass by reducing the probability that components will fail during a mission. While increased reliability can reduce maintenance logistics mass requirements, the rate of mass reduction decreases over time. In addition, reliability growth requires increased test time and cost. This paper assesses trends in test time requirements, cost, and maintenance logistics mass savings as a function of increase in Mean Time Between Failures (MTBF) for some or all of the components in a system. In general, reliability growth results in superlinear growth in test time requirements, exponential growth in cost, and sublinear benefits (in terms of logistics mass saved). These trends indicate that it is unlikely that reliability growth alone will be a cost-effective approach to maintenance logistics mass reduction and risk mitigation for long-endurance missions. This paper discusses these trends as well as other options to reduce logistics mass such as direct reduction of part mass, commonality, or In-Space Manufacturing (ISM). Overall, it is likely that some combination of all available options - including reliability growth - will be required to reduce mass and mitigate risk for future deep space missions.

  14. Maximal strength, muscular endurance and inflammatory biomarkers in young adult men.

    PubMed

    Vaara, J P; Vasankari, T; Fogelholm, M; Häkkinen, K; Santtila, M; Kyröläinen, H

    2014-12-01

    The aim was to study associations of maximal strength and muscular endurance with inflammatory biomarkers independent of cardiorespiratory fitness in those with and without abdominal obesity. 686 young healthy men participated (25±5 years). Maximal strength was measured via isometric testing using dynamo-meters to determine maximal strength index. Muscular endurance index consisted of push-ups, sit-ups and repeated squats. An indirect cycle ergometer test until exhaustion was used to estimate maximal aerobic capacity (VO2max). Participants were stratified according to those with (>102 cm) and those without abdominal obesity (<102 cm) based on waist circumference. Inflammatory factors (C-reactive protein, interleukin-6 and tumour necrosis factor alpha) were analysed from serum samples. Maximal strength and muscular endurance were inversely associated with IL-6 in those with (β=-0.49, -0.39, respectively) (p<0.05) and in those without abdominal obesity (β=-0.08, -0.14, respectively) (p<0.05) adjusted for smoking and cardio-respiratory fitness. After adjusting for smoking and cardiorespiratory fitness, maximal strength and muscular endurance were inversely associated with CRP only in those without abdominal obesity (β=-0.11, -0.26, respectively) (p<0.05). This cross-sectional study demonstrated that muscular fitness is inversely associated with C-reactive protein and IL-6 concentrations in young adult men independent of cardiorespi-ratory fitness.

  15. Selected Activities to Improve Cardiovascular Endurance and Strength and Muscular Endurance; K-3.

    ERIC Educational Resources Information Center

    Schmidt, Sharon

    Activities to help the young child improve his/her physical fitness are difficult to find because of insufficient research supporting the effectiveness of proposed activities. However, several activities are assumed to improve the fitness of various areas of the body while concurrently improving cardiovascular endurance by increasing the heart…

  16. Implicit motives and basic need satisfaction in extreme endurance sports.

    PubMed

    Schüler, Julia; Wegner, Mirko; Knechtle, Beat

    2014-06-01

    Previous research has shown that the effects of basic psychological needs on the flow experience in sports are moderated by implicit motives. However, so far, only leisure and health-oriented sports have been analyzed. In a pilot study and a main study (N = 29, 93), we tested whether the implicit achievement and affiliation motives interact with the need for competence and the need for social relatedness satisfaction, respectively, to predict flow experience and well-being in extreme endurance athletes. Results showed that highly achievement-motivated individuals benefited more from the need for competence satisfaction in terms of flow than individuals with a low achievement motive did. In addition, highly affiliation-motivated individuals whose need for social relatedness is satisfied reported higher positive affect and lower exercise addiction scores than athletes with a low motive. We discuss the differential effects of the interplay between the achievement and affiliation motives and basic needs on different outcome variables.

  17. The Enduring Behavioral Changes in Rats with Experimental Phenylketonuria*

    PubMed Central

    Andersen, Arnold E.; Rowe, Vernon; Guroff, Gordon

    1974-01-01

    The biochemical features of phenylketonuria have been reproduced in developing rat pups by administering to them a combination of p-chloro-DL-phenylalanine plus L-phenylalanine for the first 21 days after birth. During the treatment period, the experimental animals show delayed eye opening and decreased brain weight compared with controls given saline. Neuropathological examination of developing animals reveals deficient myelination and some inhibition of cerebellar maturation. When tested as adults, after a long recovery period, animals with phenylketonuria are hyperactive in activity wheels. Adult rats are deficient in reversing a position choice and demonstrate impaired performance in a Y-maze. Rats treated with p-chloro-DL-phenylalanine plus L-phenylalanine during the vulnerable period of rapid brain development thus have enduring behavioral changes that persist throughout life. Images PMID:4521053

  18. Endurance training of respiratory muscles improves cycling performance in fit young cyclists

    PubMed Central

    Holm, Paige; Sattler, Angela; Fregosi, Ralph F

    2004-01-01

    Background Whether or not isolated endurance training of the respiratory muscles improves whole-body endurance exercise performance is controversial, with some studies reporting enhancements of 50 % or more, and others reporting no change. Twenty fit (VO2 max 56.0 ml/kg/min), experienced cyclists were randomly assigned to three groups. The experimental group (n = 10) trained their respiratory muscles via 20, 45 min sessions of hyperpnea. The placebo group (n = 4) underwent "sham" training (20, 5 min sessions), and the control group (n = 6) did no training. Results After training, the experimental group increased their respiratory muscle endurance capacity by 12 %. Performance on a bicycle time trial test designed to last about 40 min improved by 4.7 % (9 of 10 subjects showed improvement). There were no test-re-test improvements in either respiratory muscle or bicycle exercise endurance performance in the placebo group, nor in the control group. After training, the experimental group had significantly higher ventilatory output and VO2, and lower PCO2, during constant work-rate exercise; the placebo and control groups did not show these changes. The perceived respiratory effort was unchanged in spite of the higher ventilation rate after training. Conclusions The results suggest that respiratory muscle endurance training improves cycling performance in fit, experienced cyclists. The relative hyperventilation with no change in respiratory effort sensations suggest that respiratory muscle training allows subjects to tolerate the higher exercise ventilatory response without more dyspnea. Whether or not this can explain the enhanced performance is unknown. PMID:15132753

  19. Respiratory muscle endurance training: effect on normoxic and hypoxic exercise performance.

    PubMed

    Keramidas, Michail E; Debevec, Tadej; Amon, Mojca; Kounalakis, Stylianos N; Simunic, Bostjan; Mekjavic, Igor B

    2010-03-01

    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.

  20. Suppression of endurance degradation by applying constant voltage stress in one-transistor and one-resistor resistive random access memory

    NASA Astrophysics Data System (ADS)

    Su, Yu-Ting; Chang, Ting-Chang; Tsai, Tsung-Ming; Chang, Kuan-Chang; Chu, Tian-Jian; Chen, Hsin-Lu; Chen, Min-Chen; Yang, Chih-Cheng; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2017-01-01

    In this letter we demonstrate an operation method that effectively suppresses endurance degradation. After many operations, the off-state of resistance random access memory (RRAM) degrades. This degradation is caused by reduction of active oxygen ions participating in the set process, as determined by current fitting of current-voltage (I-V) curves obtained from the endurance test between the interval of seventy to one hundred million operations. To address this problem, we propose the application of constant voltage stress after every five million operations during the endurance test. The experimental result shows that this method can maintain oxygen ions at the proper depth in the electrode and improve RRAM reliability.

  1. Endurance capacity and neuromuscular fatigue following high vs moderate-intensity endurance training: a randomised trial.

    PubMed

    O'Leary, Thomas J; Collett, Johnny; Howells, Ken; Morris, Martyn G

    2017-02-16

    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.

  2. 'Endurance Crater's' Dazzling Dunes (false-color)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    As NASA's Mars Exploration Rover Opportunity creeps farther into 'Endurance Crater,' the dune field on the crater floor appears even more dramatic. This false-color image taken by the rover's panoramic camera shows that the dune crests have accumulated more dust than the flanks of the dunes and the flat surfaces between them. Also evident is a 'blue' tint on the flat surfaces as compared to the dune flanks. This results from the presence of the hematite-containing spherules ('blueberries') that accumulate on the flat surfaces.

    Sinuous tendrils of sand less than 1 meter (3.3 feet) high extend from the main dune field toward the rover. Scientists hope to send the rover down to one of these tendrils in an effort to learn more about the characteristics of the dunes. Dunes are a common feature across the surface of Mars, and knowledge gleaned from investigating the Endurance dunes close-up may apply to similar dunes elsewhere.

    Before the rover heads down to the dunes, rover drivers must first establish whether the slippery slope that leads to them is firm enough to ensure a successful drive back out of the crater. Otherwise, such hazards might make the dune field a true sand trap.

  3. Whole blood selenium concentrations in endurance horses.

    PubMed

    Haggett, Emily; Magdesian, K Gary; Maas, John; Puschner, Birgit; Higgins, Jamie; Fiack, Ciara

    2010-11-01

    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.

  4. Endurance exercise performance: the physiology of champions

    PubMed Central

    Joyner, Michael J; Coyle, Edward F

    2008-01-01

    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

  5. Back end of an enduring fuel cycle

    SciTech Connect

    Pillay, K.K.S.

    1998-03-01

    An enduring nuclear fuel cycle is an essential part of sustainable consumption, the process whereby world`s riches are consumed in a responsible manner so that future generations can continue to enjoy at least some of them. In many countries, the goal of sustainable development has focused attention on the benefits of nuclear technologies. However, sustenance of the nuclear fuel cycle is dependent on sensible management of all the resources of the fuel cycle, including energy, spent fuels, and all of its side streams. The nuclear fuel cycle for energy production has suffered many traumas since the mid seventies. The common basis of technologies producing nuclear explosives and consumable nuclear energy has been a preoccupation for some, predicament for others, and a perception problem for many. It is essential to reestablish a reliable back end of the nuclear fuel cycle that can sustain the resource requirements of an enduring full cycle. This paper identifies some pragmatic steps necessary to reverse the trend and to maintain a necessary fuel cycle option for the future.

  6. THE RELATIONSHIP BETWEEN CORE ENDURANCE AND BACK DYSFUNCTION IN COLLEGIATE MALE ATHLETES WITH AND WITHOUT NONSPECIFIC LOW BACK PAIN

    PubMed Central

    Abdelraouf, Osama Ragaa

    2016-01-01

    ABSTRACT Background Physical activity and sports can be associated with low back pain. However, little is known about the relationship between core stability and nonspecific low back pain (LBP) among athletes. Purpose The purpose of this study was to investigate the relationship between core endurance and back dysfunction in collegiate male athletes with and without nonspecific LBP. Methods Fifty-five male collegiate athletes from a variety of sports were recruited for this study. Their mean age was 21.50 ± (2.54) years, mean weight was 70.96 ± (5.33) kg., and mean height was 174.38 ± (4.37) cm. Thirty athletes with non-specific LBP and twenty five healthy athletes were assessed using McGill's anterior, posterior, and left and right plank core endurance tests (seconds) and for dysfunction using the Micheli functional scale (MFS). Pearson's product moment correlations examined the relationships between core endurance and MFS. Results There were significant differences regarding the measured core endurance tests between the healthy athletes group and the nonspecific LBP group (p < 0.05). Additionally, good negative (r = −0.794) and moderate negative (r = −0.541) correlations were found between MFS and trunk extensor and flexor endurance tests, respectively in the group with nonspecific LBP. Conclusion The results of this study imply that poor core endurance is likely associated with nonspecific LBP in collegiate athletes. Injury risk reduction and back management programs for the athletic population should include strategies that emphasize endurance of the core muscles especially the trunk extensors and flexors. Level of Evidence 2b PMID:27274419

  7. Human torque velocity adaptations to sprint, endurance, or combined modes of training

    NASA Technical Reports Server (NTRS)

    Shealy, M. J.; Callister, R.; Dudley, G. A.; Fleck, S. J.

    1992-01-01

    We had groups of athletes perform sprint and endurance run training independently or concurrently for 8 weeks to examine the voluntary in vivo mechanical responses to each type of training. Pre- and posttraining angle-specific peak torque during knee extension and flexion were determined at 0, 0.84, 1.65, 2.51, 3.35, 4.19, and 5.03 radian.sec-1 and normalized for lean body mass. Knee extension torque in the sprint-trained group increased across all test velocities, the endurance-trained group increased at 2.51, 3.34, 4.19, and 5.03 radian.sec-1, and the group performing the combined training showed no change at any velocity. Knee flexion torque of the sprint and combined groups decreased at 0.84, 1.65, and 2.51 radian.sec-1. Knee flexion torque in the sprint-trained group also decreased at 0 radian.sec-1 and in the combined group at 3.34 radian.sec-1. Knee flexion torque in the endurance-trained group showed no change at any velocity of contraction. Mean knee flexion:extension ratios across the test velocities significantly decreased in the sprint-trained group. Knee extension endurance during 30 seconds of maximal contractions significantly increased in all groups. Only the sprint-trained group showed a significant increase in endurance of the knee flexors. These data suggest that changes in the voluntary in vivo mechanical characteristics of knee extensor and flexor skeletal muscles are specific to the type of run training performed.

  8. Muscle mechanical properties of strength and endurance athletes and changes after one week of intensive training.

    PubMed

    de Paula Simola, Rauno Álvaro; Raeder, Christian; Wiewelhove, Thimo; Kellmann, Michael; Meyer, Tim; Pfeiffer, Mark; Ferrauti, Alexander

    2016-10-01

    The study investigates whether tensiomyography (TMG) is sensitive to differentiate between strength and endurance athletes, and to monitor fatigue after either one week of intensive strength (ST) or endurance (END) training. Fourteen strength (24.1±2.0years) and eleven endurance athletes (25.5±4.8years) performed an intensive training period of 6days of ST or END, respectively. ST and END groups completed specific performance tests as well as TMG measurements of maximal radial deformation of the muscle belly (Dm), deformation time between 10% and 90% Dm (Tc), rate of deformation development until 10% Dm (V10) and 90% Dm (V90) before (baseline), after training period (post1), and after 72h of recovery (post2). Specific performance of both groups decreased from baseline to post1 (P<0.05) and returned to baseline values at post2 (P<0.05). The ST group showed higher countermovement jump (P<0.05) and shorter Tc (P<0.05) at baseline. After training, Dm, V10, and V90 were reduced in the ST (P<0.05) while TMG changes were less pronounced in the END. TMG could be a useful tool to differentiate between strength and endurance athletes, and to monitor fatigue and recovery especially in strength training.

  9. Concurrent strength and endurance training: the influence of dependent variable selection.

    PubMed

    Leveritt, Michael; Abernethy, Peter J; Barry, Ben; Logan, Peter A

    2003-08-01

    Twenty-six active university students were randomly allocated to resistance (R, n = 9), endurance (E, n = 8), and concurrent resistance and endurance (C, n = 9) training conditions. Training was completed 3 times per week in all conditions, with endurance training preceding resistance training in the C group. Resistance training involved 4 sets of upper- and lower-body exercises with loads of 4-8 repetition maximum (RM). Each endurance training session consisted of five 5-minute bouts of incremental cycle exercise at between 40 and 100% of peak oxygen uptake (.VO2peak). Parameters measured prior to and following training included strength (1RM and isometric and isokinetic [1.04, 3.12, 5.20, and 8.67 rad.s(-1)] strength), .VO2peak and Wingate test performance (peak power output [PPO], average power, and relative power decline). Significant improvements in 1RM strength were observed in the R and C groups following training. .VO2peak significantly increased in E and C but was significantly reduced in R after training. Effect size (ES) transformations on the other dependent variables suggested that performance changes in the C group were not always similar to changes in the R or E groups. These ES data suggest that statistical power and dependent variable selection are significant issues in enhancing our insights into concurrent training. It may be necessary to assess a range of performance parameters to monitor the relative effectiveness of a particular concurrent training regimen.

  10. A Typology of Marital Quality of Enduring Marriages in Israel

    ERIC Educational Resources Information Center

    Cohen, Orna; Geron, Yael; Farchi, Alva

    2010-01-01

    This article presents a typology of enduring marriages of Israeli couples married for at least 40 years. Based on the view that marital quality is a multidimensional phenomenon, the typology is derived from a cluster analysis of responses of husbands and wives in 51 couples to the ENRICH scale items. Three types of enduring marriages were found:…

  11. Endurance Factors Improve Hippocampal Neurogenesis and Spatial Memory in Mice

    ERIC Educational Resources Information Center

    Kobilo, Tali; Yuan, Chunyan; van Praag, Henriette

    2011-01-01

    Physical activity improves learning and hippocampal neurogenesis. It is unknown whether compounds that increase endurance in muscle also enhance cognition. We investigated the effects of endurance factors, peroxisome proliferator-activated receptor [delta] agonist GW501516 and AICAR, activator of AMP-activated protein kinase on memory and…

  12. Lower Muscle Endurance in Patients with Alcoholic Liver Disease

    ERIC Educational Resources Information Center

    Andersen, Henning; Aagaard, Niels K.; Jakobsen, Johannes; Dorup, Inge; Vilstrup, Hendrik

    2012-01-01

    Patients with alcoholic liver disease often complain of restricted physical capacity, which could be due to decreased muscle endurance. The aim of this study was to assess the muscular endurance in patients with alcoholic liver disease. In a cross sectional study, 24 patients with alcoholic liver disease and 22 controls were evaluated using…

  13. The enduring scientific contributions of Sigmund Freud.

    PubMed

    Gedo, John E

    2002-01-01

    Through the development of a novel observational method, Sigmund Freud made possible the collection of reliable data about man's inner life. The scientific hypotheses he formulated about these formed the initial version of psychoanalysis. Many of these first thoughts have had to be revised in the light of subsequent scientific findings about the operations of the central nervous system, but even these refuted propositions often had much heuristic value. Despite the passage of a whole century, many Freudian hypotheses have retained their scientific standing. Most important among these was Freud's realization that human thought is usually unconscious. His understanding of the role of the automatic repetition of basic patterns of behavior, of the fateful consequences of early childhood emotional vicissitudes in structuring enduring mental dispositions, and of the distinction between two distinct modes of thinking are the most significant among his many contributions.

  14. (-)-Hydroxycitrate ingestion and endurance exercise performance.

    PubMed

    Lim, Kiwon; Ryu, Sungpil; Suh, Heajung; Ishihara, Kengo; Fushiki, Tohru

    2005-02-01

    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.

  15. Effects of curative treatment emphasizing endurance training on the performance and blood pressure of hypertensive and normotensives

    NASA Technical Reports Server (NTRS)

    Worms, F.

    1981-01-01

    The problem of normal values of blood pressure after exercise taking into account the blood pressure at the end of the exercise test is discussed. Hypertensives showed a lower working capacity than normotensives. In normotensives, however, systolic blood pressure at the end of an exercise correlated well with the working capacity. After the endurance cure submaximal blood pressure was markedly lower in hypertensives with a striking dependence on the level of initial values. Systolic blood pressure at the end of an exercise test was not changed significantly. Most probably it is not possible to overcome this malregulation in hypertensives by endurance training alone.

  16. Upper-body muscular endurance in female university-level modern dancers: a pilot study.

    PubMed

    Ambegaonkar, Jatin P; Caswell, Shane V; Winchester, Jason B; Caswell, Amanda A; Andre, Matthew J

    2012-03-01

    Physical demands vary among dance styles, and injury patterns differ accordingly. Modern dance tends to be high in upper-body demands, and university-level female modern dancers are suggested to be at high risk for upper-body injury. Low muscular endurance is a known injury risk factor. Whether modern dancers have different upper-body muscular endurance than non-dancers is unclear. Thus, the purpose of this study was to compare upper-body endurance in female university-level modern dancers (n = 17) and physically active non-dancers (n = 15), using the modified push-up test. Pearson-correlations examined relationships between anthropometrics and push-ups. Multiple regression analyses were used to determine whether anthropometrics and physical activity could predict push-up scores. One-way ANOVAs compared upper-body endurance (number of push-ups) and physical activity between groups (p < 0.05). Except for height (r = -.37), no variables were related to push-ups. Neither anthropometrics nor physical activity were able to predict push-up scores (p = 0.25). Despite dancers being more active/day (3.6 ± 1.9 vs. 0.9 ± 0.4 hrs/day, p < 0.001), more times per week (5.4 ± 1.2 vs. 4.0 ± 1.8, p = 0.02), and having greater overall physical activity volumes (20.4 ± 11.4 vs. 3.3 ± 2.5 hrs/week, p < 0.001) than non-dancers, both groups had similar upper-body endurance (22.2 ± 8.6 vs. 19.9 ± 8.2, p = 0.44). A probable explanation for this similarity exists in the lack of physical activity beyond dance itself performed by the dancers; our preliminary work suggests that modern dance alone may not produce upper-body muscle endurance gains. Hence, it is suggested that modern dancers should engage in strength and conditioning training programs to enhance upper-body endurance.

  17. Effects of plyometric training on endurance and explosive strength performance in competitive middle- and long-distance runners.

    PubMed

    Ramírez-Campillo, Rodrigo; Alvarez, Cristian; Henríquez-Olguín, Carlos; Baez, Eduardo B; Martínez, Cristian; Andrade, David C; Izquierdo, Mikel

    2014-01-01

    The purpose of this study was to examine the effect of a short-term plyometric training program on explosive strength and endurance performance in highly competitive middle- and long-distance runners. Athletes were randomly assigned to a control group (CG, n = 18, 12 men) and an explosive strength training group (TG, n = 18, 10 men). Drop jump (DJ) from 20 (DJ20) and 40 cm (DJ40), countermovement jump with arms (CMJA), 20-m sprint time, and 2.4-km endurance run time test were carried out before and after 6 weeks of explosive strength training. Also, the combined standardized performance (CSP) in the endurance and explosive strength test was analyzed. After intervention, the CG did not show any significant change in performance, whereas the TG showed a significant reduction in 2.4-km endurance run time (-3.9%) and 20-m sprint time (-2.3%) and an increase in CMJA (+8.9%), DJ20 (+12.7%), and DJ40 (16.7%) explosive performance. Strength training group also exhibited a significant increase in CSP, although the CG showed significant reduction. We conclude that properly programmed concurrent explosive strength and endurance training could be advantageous for middle- and long-distance runners in their competitive performance, especially in events characterized by sprinting actions with small time differences at the end of the race.

  18. The acute effects of a caffeine-containing supplement on strength, muscular endurance, and anaerobic capabilities.

    PubMed

    Beck, Travis W; Housh, Terry J; Schmidt, Richard J; Johnson, Glen O; Housh, Dona J; Coburn, Jared W; Malek, Moh H

    2006-08-01

    The purpose of this study was to examine the acute effects of a caffeine-containing supplement on upper- and lower-body strength and muscular endurance as well as anaerobic capabilities. Thirty-seven resistance-trained men (mean +/- SD, age: 21 +/- 2 years) volunteered to participate in this study. On the first laboratory visit, the subjects performed 2 Wingate Anaerobic Tests (WAnTs) to determine peak power (PP) and mean power (MP), as well as tests for 1 repetition maximum (1RM), dynamic constant external resistance strength, and muscular endurance (TOTV; total volume of weight lifted during an endurance test with 80% of the 1RM) on the bilateral leg extension (LE) and free-weight bench press (BP) exercises. Following a minimum of 48 hours of rest, the subjects returned to the laboratory for the second testing session and were randomly assigned to 1 of 2 groups: a supplement group (SUPP; n = 17), which ingested a caffeine-containing supplement, or a placebo group (PLAC; n = 20), which ingested a cellulose placebo. One hour after ingesting either the caffeine-containing supplement or the placebo, the subjects performed 2 WAnTs and were tested for 1RM strength and muscular endurance on the LE and BP exercises. The results indicated that there was a significant (p < 0.05) increase in BP 1RM for the SUPP group, but not for the PLAC group. The caffeine-containing supplement had no effect, however, on LE 1RM, LE TOTV, BP TOTV, PP, and MP. Thus, the caffeine-containing supplement may be an effective supplement for increasing upper-body strength and, therefore, could be useful for competitive and recreational athletes who perform resistance training.

  19. Cardiac autonomic control in high level Brazilian power and endurance track-and-field athletes.

    PubMed

    Abad, C C C; do Nascimento, A M; Gil, S; Kobal, R; Loturco, I; Nakamura, F Y; Mostarda, C T; Irigoyen, M C

    2014-08-01

    The autonomic nervous system (ANS) has an important role in physical performance. However, the cardiac ANS activity in high-level track and field athletes has been poorly explored. Thus, we tested the hypothesis that endurance and power athletes would present a markedly different cardiac autonomic control at rest. We analyzed the cardiac ANS by means of time and frequency domains heart rate variability (HRV) analyses and by symbolic analysis. Endurance athletes showed higher pulse interval than power athletes (1,265±126 vs. 1,031±98 ms respectively; p<0.05). No differences were found in time and frequency domains between the groups. However, the LF%, HF% and LF/HF ratio presented high effect sizes (1.46, 1.46 and 1.30, respectively). The symbolic analysis revealed that endurance athletes had higher 2V parasympathetic modulation (36±6.5) than power athletes (24±9.3; p<0.05). A reduced 0V sympathetic modulation was observed in endurance athletes (21±9.9) compared to power athletes (33±11; p<0.05 and ES=1.30). Our results suggest greater parasympathetic modulation and less sympathetic modulation in endurance athletes compared to power athletes. Additionally, the type of HRV analysis needs to be chosen with well-defined criteria and caution because their use in assessing cardiac autonomic modulation can interfere with the interpretation of results. In practical terms, symbolic analysis appears to better discriminate between cardiac autonomic activities of athletes with different training backgrounds than frequency domain analysis.

  20. Effect of Sequencing Strength and Endurance Training in Young Male Soccer Players.

    PubMed

    Makhlouf, Issam; Castagna, Carlo; Manzi, Vincenzo; Laurencelle, Louis; Behm, David G; Chaouachi, Anis

    2016-03-01

    This study examined the effects of strength and endurance training sequence (strength before or after endurance) on relevant fitness variables in youth soccer players. Fifty-seven young elite-level male field soccer players (13.7 ± 0.5 years; 164 ± 8.3 cm; 53.5 ± 8.6 kg; body fat; 15.6 ± 3.9%) were randomly assigned to a control (n = 14, CG) and 3 experimental training groups (twice a week for 12 weeks) strength before (SE, n = 15), after (ES, n = 14) or on alternate days (ASE, n = 14) with endurance training. A significant (p = 0.001) intervention main effect was detected. There were only trivial training sequence differences (ES vs. SE) for all variables (p > 0.05). The CG showed large squat 1 repetition maximum (1RM) and medium sprint, change of direction ability, and jump improvements. ASE demonstrated a trivial difference in endurance performance with ES and SE (p > 0.05). Large to medium greater improvements for SE and ES were reported compared with ASE for sprinting over 10 and 30 m (p < 0.02). The SE squat 1RM was higher than in ASE (moderate, p < 0.02). Postintervention differences between ES and SE with CG fitness variables were small to medium (p ≤ 0.05) except for a large SE advantage with the Yo-Yo intermittent recovery test (p < 0.001, large). This study showed no effect of intrasession training sequence on soccer fitness-relevant variables. However, combining strength and endurance within a single training session provided superior results vs. training on alternate days. Concurrent training may be considered as an effective and safe training method for the development of the prospective soccer player.

  1. mDurance: A Novel Mobile Health System to Support Trunk Endurance Assessment

    PubMed Central

    Banos, Oresti; Moral-Munoz, Jose Antonio; Diaz-Reyes, Ignacio; Arroyo-Morales, Manuel; Damas, Miguel; Herrera-Viedma, Enrique; Hong, Choong Seon; Lee, Sungyong; Pomares, Hector; Rojas, Ignacio; Villalonga, Claudia

    2015-01-01

    Low back pain is the most prevalent musculoskeletal condition. This disorder constitutes one of the most common causes of disability worldwide, and as a result, it has a severe socioeconomic impact. Endurance tests are normally considered in low back pain rehabilitation practice to assess the muscle status. However, traditional procedures to evaluate these tests suffer from practical limitations, which potentially lead to inaccurate diagnoses. The use of digital technologies is considered here to facilitate the task of the expert and to increase the reliability and interpretability of the endurance tests. This work presents mDurance, a novel mobile health system aimed at supporting specialists in the functional assessment of trunk endurance by using wearable and mobile devices. The system employs a wearable inertial sensor to track the patient trunk posture, while portable electromyography sensors are used to seamlessly measure the electrical activity produced by the trunk muscles. The information registered by the sensors is processed and managed by a mobile application that facilitates the expert's normal routine, while reducing the impact of human errors and expediting the analysis of the test results. In order to show the potential of the mDurance system, a case study has been conducted. The results of this study prove the reliability of mDurance and further demonstrate that practitioners are certainly interested in the regular use of a system of this nature. PMID:26057034

  2. Effects of Heavy Strength Training on Running Performance and Determinants of Running Performance in Female Endurance Athletes

    PubMed Central

    Vikmoen, Olav; Raastad, Truls; Seynnes, Olivier; Bergstrøm, Kristoffer; Ellefsen, Stian; Rønnestad, Bent R.

    2016-01-01

    Purpose The purpose of the current study was to investigate the effects of adding strength training to normal endurance training on running performance and running economy in well-trained female athletes. We hypothesized that the added strength training would improve performance and running economy through altered stiffness of the muscle-tendon complex of leg extensors. Methods Nineteen female endurance athletes [maximal oxygen consumption (VO2max): 53±3 ml∙kg-1∙min-1, 5.8 h weekly endurance training] 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 leg exercises [3 x 4–10 repetition maximum (RM)], twice a week for 11 weeks. Muscle strength, 40 min all-out running distance, running performance determinants and patellar tendon stiffness were measured before and after the intervention. Results E+S increased 1RM in leg exercises (40 ± 15%) and maximal jumping height in counter movement jump (6 ± 6%) and squat jump (9 ± 7%, p < 0.05). This was accompanied by increased muscle fiber cross sectional area of both fiber type I (13 ± 7%) and fiber type II (31 ± 20%) in m. vastus lateralis (p < 0.05), with no change in capillary density in m. vastus lateralis or the stiffness of the patellar tendon. Neither E+S nor E changed running economy, fractional utilization of VO2max or VO2max. There were also no change in running distance during a 40 min all-out running test in neither of the groups. Conclusion Adding heavy strength training to endurance training did not affect 40 min all-out running performance or running economy compared to endurance training only. PMID:26953893

  3. Elevated Temperature Fatigue Endurance of Three Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Verrilli, Michael J.

    2007-01-01

    High-cycle fatigue endurance of three candidate materials for the acoustic liners of the Enabling Propulsion Materials Nozzle Program was investigated. The ceramic matrix composite materials investigated were N720/AS (Nextel 720, 3M Corporation), Sylramic S200 (Dow Corning), and UT 22. High-cycle fatigue tests were conducted in air at 910 C on as-machined specimens and on specimens subjected to tensile cyclic load excursions every 160 hr followed by thermal exposure at 910 C in a furnace up to total exposure times of 2066 and 4000 hr. All the fatigue tests were conducted in air at 100 Hz with a servohydraulic test machine. In the as-machined condition, among the three materials investigated only the Sylramic S200 exhibited a deterministic type of high-cycle fatigue behavior. Both the N720/AS and UT-22 exhibited significant scatter in the experimentally observed high-cycle fatigue lives. Among the thermally exposed specimens, N720/AS and Sylramic S200 materials exhibited a reduction in the high-cycle fatigue lives, particularly at the exposure time of 4000 hr.

  4. Increased Blood Lactate Level Deteriorates Running Economy in World Class Endurance Athletes.

    PubMed

    Hoff, Jan; Støren, Øyvind; Finstad, Arnstein; Wang, Eivind; Helgerud, Jan

    2016-05-01

    Blood lactate accumulation is associated with development of muscle fatigue and negatively correlated to endurance performance. No research has quantified the effects of lactate presence at moderate levels of lactate accumulation. The purpose of this study was to test whether 2 moderate blood lactate concentration levels affect running economy (RE) when running at the individual lactate threshold (LT). Seven male world class endurance athletes with an average V[Combining Dot Above]O2max of 80.7 ± 2.7 ml·kg·min or 5.8 ± 0.5 L·min participated in this study. After the V[Combining Dot Above]O2max test, the subjects were resting or walking and in a random order tested for RE at their LT velocity when the blood lactate level reached either 3 mmol·L or 5 mmol·L. After a new 5-minute exercising period at maximal aerobic velocity, the crossover lactate value RE testing was performed. Running economy was significantly (p ≤ 0.05) deteriorated from 0.668 ± 0.044 to 0.705 ± 0.056 ml·kg·m or 5.5% (p ≤ 0.05) for blood lactate level of 3 mmol·L compared with 5 mmol·L, respectively. Increased lactate level from 3 to 5 mmol·L is thus accompanied by deteriorated RE at LT running velocity. The deteriorated RE at moderate levels of lactate concentration emphasizes the importance of avoiding intensities above LT in the early parts of a dominantly aerobic endurance competition. It also emphasizes the importance of a high V[Combining Dot Above]O2max for aerobic endurance athletes and may partly explain the V[Combining Dot Above]O2 slow component as impaired RE.

  5. Innovative Operations Measures and Nutritional Support for Mass Endurance Events.

    PubMed

    Chiampas, George T; Goyal, Anita V

    2015-11-01

    Endurance and sporting events have increased in popularity and participation in recent years worldwide, and with this comes the need for medical directors to apply innovative operational strategies and nutritional support to meet such demands. Mass endurance events include sports such as cycling and running half, full and ultra-marathons with over 1000 participants. Athletes, trainers and health care providers can all agree that both participant outcomes and safety are of the utmost importance for any race or sporting event. While demand has increased, there is relatively less published guidance in this area of sports medicine. This review addresses public safety, operational systems, nutritional support and provision of medical care at endurance events. Significant medical conditions in endurance sports include heat illness, hyponatraemia and cardiac incidents. These conditions can differ from those typically encountered by clinicians or in the setting of low-endurance sports, and best practices in their management are discussed. Hydration and nutrition are critical in preventing these and other race-related morbidities, as they can impact both performance and medical outcomes on race day. Finally, the command and communication structures of an organized endurance event are vital to its safety and success, and such strategies and concepts are reviewed for implementation. The nature of endurance events increasingly relies on medical leaders to balance safety and prevention of morbidity while trying to help optimize athlete performance.

  6. The effect of carbohydrate mouth rinse on maximal strength and strength endurance.

    PubMed

    Painelli, Vitor S; Roschel, Hamilton; Gualano, Bruno; Del-Favero, Serena; Benatti, Fabiana B; Ugrinowitsch, Carlos; Tricoli, Valmor; Lancha, Antonio H

    2011-09-01

    It has been previously reported that carbohydrate (CHO) mouth rinse can improve exercise performance. The proposed mechanism involves increased activation of brain regions believed to be responsible for reward/motivation and motor control. Since strength-related performance is affected by central drive to the muscles, it seems reasonable to hypothesize that the positive CNS response to oral CHO sensing may counteract the inhibitory input from the muscle afferent pathways minimizing the drop in the central drive. The purpose of the current study was to test if CHO mouth rinse affects maximum strength and strength endurance performance. Twelve recreationally strength-trained healthy males (age 24.08 ± 2.99 years; height 178.09 ± 6.70 cm; weight 78.67 ± 8.17 kg) took part in the study. All of the tests were performed in the morning, after an 8 h overnight fasting. Subjects were submitted to a maximum strength test (1-RM) and a strength endurance test (six sets until failure at 70% of 1-RM), in separate days under three different experimental conditions (CHO mouth rinse, placebo-PLA mouth rinse and control-CON) in a randomized crossover design. The CHO mouth rinse (25 ml) occurred before every attempt in the 1-RM test, and before every set in the endurance strength test. Blood glucose and lactate were measured immediately before and 5 min post-tests. There were no significant differences in 1-RM between experimental conditions (CHO 101 ± 7.2 kg; PLA 101 ± 7.4 kg; CON 101 ± 7.2 kg; p = 0.98). Furthermore, there were no significance between trial differences in the number of repetitions performed in each set (p = 0.99) or the total exercise volume (number of repetitions × load lifted [kg]) (p = 0.98). A main effect for time (p < 0.0001) in blood lactate concentration was observed in both tests (1-RM and strength endurance). Blood glucose concentration did not differ between conditions. In conclusion, CHO mouth rinse does not affect maximum strength or strength

  7. Effect of sex and menstrual cycle in women on starting speed, anaerobic endurance and muscle power.

    PubMed

    Wiecek, M; Szymura, J; Maciejczyk, M; Cempla, J; Szygula, Z

    2016-03-01

    The aim of our study was to compare the indicators of starting speed, anaerobic endurance and power in women as well as men, and to investigate whether the values of these indicators differ in women during the follicular and luteal phases of the menstrual cycle. The studied group included 16 men and 16 women. The subjects performed the 20-second maximal cycling sprint test. The men performed the test twice at 14-day intervals. The women undertook the test 4 times: twice during the middle of follicular phase and twice in the middle of luteal phase in separate menstrual cycles. Hormonal changes during the menstrual cycle do not influence anaerobic performance, starting speed or anaerobic endurance in women. Anaerobic performance in men is higher than in women with similar aerobic performance expressed as VO2max/LBM (lean body mass). A lower power decrease with time was noted for women than men, with a similar time of maintaining power in both groups. This is evidence of women's better anaerobic endurance compared to men. At the same time, the men had significantly better starting speed rates than women.

  8. Modeling of Moguls on an Endurance Test Course

    DTIC Science & Technology

    2007-06-01

    actual profile. Sandu et al (2005) has proposed terrain synthesis based on polynomial chaos . Sandu and Li (2007) recently proposed terrain...synthesis based on ARMA and ARIMA models. Sun et al (2005) applied uniform modulated processes (UMP) and empirical mode decomposition ( EMD ) to the

  9. Fatigue Endurance Testing of Ion Implanted Roller Bearings.

    DTIC Science & Technology

    1980-10-01

    PROJECT. TASK AREA 4 WORK UNIT NUMBERS TW Bearings Division 62241N 402 Chandler Street 6,:401 Jamestown, ’,T 14701 q72_P I coNTROL.LNOG QFFICZ MN!A...combination of scuffing (due to skewing) and heavy load. Rollers tend to wobble or skew as they travel around a race, par- ticularly in an unloaded or

  10. [Endurance training and cardial adaptation (athlete's heart)].

    PubMed

    Dickhuth, Hans-Hermann; Röcker, Kai; Mayer, Frank; König, Daniel; Korsten-Reck, Ulrike

    2004-06-01

    One essential function of the cardiovascular system is to provide an adequate blood supply to all organs, including the skeletal muscles at rest and during exercise. Adaptation to chronic exercise proceeds mainly via the autonomic nervous system. On the one hand, peripheral muscles influence the autonomic reactions through "feedback" control via ergoreceptors, in particular, mechano- and chemoreceptors. On the other hand, there is central control in the sense of a "feed forward" regulation, e. g., the reaction of an athlete before competition. Along with other influential factors, such as circulatory presso-, chemo-, and volume receptors, the incoming impulses are processed in vegetative centers.A cardiovascular reaction, then, is the result of nerval and humoral sympathetic and parasympathetic activity. At rest, the parasympathetic tone dominates. It reduces heart frequency and conduction velocity. The high vagal tone is initially reduced with increasing physical exertion and switches at higher intensity to increasingly sympathetic activation. This mechanism of reaction to exercise is supported by inverse central and peripheral transmissions.Chronic endurance training leads to an improved local aerobic capacity of the exercised musculature. At rest, it augments parasympathetic activity when the muscle mass is sufficiently large, i. e., 20-30% of the skeletal musculature. The extent of the adaptation depends on individual factors, such as scope, intensity of training, and type of muscle fiber. A higher vagal tone delays the increase in the sympathetic tone during physical exertion. The regulatory range of heart rate, contractility, diastolic function, and blood pressure is increased. In addition, adaptation results in functional and structural changes in the vascular system. Cardiocirculatory work is economized, and maximum performance and oxygen uptake are improved. Endurance training exceeding an individual limit causes harmonic enlargement and hypertrophy of the

  11. Non-conscious visual cues related to affect and action alter perception of effort and endurance performance

    PubMed Central

    Blanchfield, Anthony; Hardy, James; Marcora, Samuele

    2014-01-01

    The psychobiological model of endurance performance proposes that endurance performance is determined by a decision-making process based on perception of effort and potential motivation. Recent research has reported that effort-based decision-making during cognitive tasks can be altered by non-conscious visual cues relating to affect and action. The effects of these non-conscious visual cues on effort and performance during physical tasks are however unknown. We report two experiments investigating the effects of subliminal priming with visual cues related to affect and action on perception of effort and endurance performance. In Experiment 1 thirteen individuals were subliminally primed with happy or sad faces as they cycled to exhaustion in a counterbalanced and randomized crossover design. A paired t-test (happy vs. sad faces) revealed that individuals cycled significantly longer (178 s, p = 0.04) when subliminally primed with happy faces. A 2 × 5 (condition × iso-time) ANOVA also revealed a significant main effect of condition on rating of perceived exertion (RPE) during the time to exhaustion (TTE) test with lower RPE when subjects were subliminally primed with happy faces (p = 0.04). In Experiment 2, a single-subject randomization tests design found that subliminal priming with action words facilitated a significantly longer TTE (399 s, p = 0.04) in comparison to inaction words. Like Experiment 1, this greater TTE was accompanied by a significantly lower RPE (p = 0.03). These experiments are the first to show that subliminal visual cues relating to affect and action can alter perception of effort and endurance performance. Non-conscious visual cues may therefore influence the effort-based decision-making process that is proposed to determine endurance performance. Accordingly, the findings raise notable implications for individuals who may encounter such visual cues during endurance competitions, training, or health related exercise. PMID:25566014

  12. The effects of ionized and nonionized compression garments on sprint and endurance cycling.

    PubMed

    Burden, Richard J; Glaister, Mark

    2012-10-01

    The aim of this study was to examine the effects of ionized and nonionized compression tights on sprint and endurance cycling performance. Using a randomized, blind, crossover design, 10 well-trained male athletes (age: 34.6 ± 6.8 years, height: 1.80 ± 0.05 m, body mass: 82.2 ± 10.4 kg, VO2max: 50.86 ± 6.81 ml·kg(-1)·min(-1)) performed 3 sprint trials (30-second sprint at 150% of the power output required to elicit VO2max [pVO2max] + 3 minutes recovery at 40% pVO2max + 30-second Wingate test + 3 minutes recovery at 40% pVO2max) and 3 endurance trials (30 minutes at 60% pVO2max + 5 minutes stationary recovery + 10-km time trial) wearing nonionized compression tights, ionized compression tights, or standard running tights (control). There was no significant effect of garment type on key Wingate measures of peak power (grand mean: 1,164 ± 219 W, p = 0.812), mean power (grand mean: 716 ± 68 W, p = 0.800), or fatigue (grand mean: 66.5 ± 6.9%, p = 0.106). There was an effect of garment type on blood lactate in the sprint and the endurance trials (p < 0.05), although post hoc tests only detected a significant difference between the control and the nonionized conditions in the endurance trial (mean difference: 0.55 mmol·L(-1), 95% likely range: 0.1-1.1 mmol·L(-1)). Relative to control, oxygen uptake (p = 0.703), heart rate (p = 0.774), and time trial performance (grand mean: 14.77 ± 0.74 minutes, p = 0.790) were unaffected by either type of compression garment during endurance cycling. Despite widespread use in sport, neither ionized nor nonionized compression tights had any significant effect on sprint or endurance cycling performance.

  13. Effect of endurance training on dental erosion, caries, and saliva.

    PubMed

    Frese, C; Frese, F; Kuhlmann, S; Saure, D; Reljic, D; Staehle, H J; Wolff, D

    2015-06-01

    The aim of this investigation was to give insights into the impact of endurance training on oral health, with regard to tooth erosion, caries, and salivary parameters. The study included 35 triathletes and 35 non-exercising controls. The clinical investigation comprised oral examination, assessment of oral status with special regard to caries and erosion, saliva testing during inactivity, and a self-administered questionnaire about eating, drinking, and oral hygiene behavior. In addition, athletes were asked about their training habits and intake of beverages and sports nutrition. For saliva assessment during exercise, a subsample of n = 15 athletes volunteered in an incremental running field test (IRFT). Athletes showed an increased risk for dental erosion (P = 0.001). No differences were observed with regard to caries prevalence and salivary parameters measured during inactivity between athletes and controls. Among athletes, a significant correlation was found between caries prevalence and the cumulative weekly training time (r = 0.347, P = 0.04). In athletes after IRFT and at maximum workload, saliva flow rates decreased (P = 0.001 stimulated; P = 0.01 unstimulated) and saliva pH increased significantly (P = 0.003). Higher risk for dental erosions, exercise-dependent caries risk, and load-dependent changes in saliva parameters point out the need for risk-adapted preventive dental concepts in the field of sports dentistry.

  14. Application of pre-participation cardiovascular screening guidelines to novice older runners and endurance athletes

    PubMed Central

    Abbatemarco, Justin R; Bennett, Courtney; Bell, Adrian J; Dunne, Laura; Matsumura, Martin E

    2016-01-01

    Objectives: Despite robust growth in participation in marathons and endurance sports among older individuals, guidance regarding pre-participation cardiovascular evaluation of these athletes is lacking. The objective of this study was to assess the utility of currently available pre-participation cardiovascular evaluation guidelines as applied to a cohort of older novice endurance athletes. Methods: We applied data from 1457 novice runners and endurance athletes aged 35 years and older to two pre-participation screening tools, the American Heart Association/American College of Sports Medicine Pre-Participation Questionnaire and the 2001 Working Group recommendations for pre-participation screening of masters athletes (2001 Masters). Results: Application of the American Heart Association/American College of Sports Medicine Pre-Participation Questionnaire identified 42.1% for which pre-participation cardiovascular evaluation was indicated. Of those who met criteria, 51.5% reported completion of a healthcare evaluation. Application of the 2001 Masters guidelines identified 75.2% who qualified for pre-participation electrocardiogram and 34.0% for pre-participation stress testing. Of those who met 2001 Masters criteria for pre-participation testing, 43.7% and 24.6% underwent recommended electrocardiogram and stress testing, respectively. While there was modest concordance with recommendations for pre-participation evaluations based on both American Heart Association/American College of Sports Medicine Pre-Participation Questionnaire and 2001 Masters, only athlete age was independently associated with completion of a pre-participation healthcare evaluation and only athlete age and athlete’s participation in marathons were independently associated with pre-participation stress testing. Conclusion: Among older novice endurance athletes, application of the American Heart Association/American College of Sports Medicine Pre-Participation Questionnaire and 2001 Masters

  15. Local critical power is an index of local endurance.

    PubMed

    Le Chevalier, J M; Vandewalle, H; Thépaut-Mathieu, C; Stein, J F; Caplan, L

    2000-01-01

    The hypothesis that critical power (CP) is significantly lower than the maximal aerobic power of the knee extensors has been tested in nine endurance-trained subjects, seven gymnasts and seven weight lifters. CP was calculated as being equal to the slope of the linear relationship between exhaustion time and work performed at exhaustion on a knee-extension ergometer. CP was compared with the power output at the end of a progressive knee-extension exercise (P(peak)) and the power outputs corresponding to exhaustion times equal to 4 (P(4 min)), 6 (P(6 min)), 8 (P(8 min)) and 10 min (P(10 min)), calculated according to the linear relationship between work and exhaustion time. The hypothesis that CP corresponds to a steady state in metabolic and physiological parameters was tested in the gymnasts and the weight lifters by comparing CP with the fatigue thresholds of the integrated electromyogram (iEMG(FT)), lactate level (La(FT)), oxygen uptake (VO(2FT)) and heart rate (HR(FT)). The results of the present study demonstrate that the value of CP of a local exercise cannot be considered as the equivalent of the maximal aerobic power for general exercises. The values of P(4 min), P(6 min), P(8 min), P(10 min) and P(peak) were significantly higher than CP, and corresponded to 138, 126, 119, 115 and 151% CP, respectively. The results of the present study indicate that CP can be considered as an index of muscular endurance. Indeed, La(FT), iEMG (FT), VO(2FT) and HR(FT) were not significantly different from CP. All of these fatigue thresholds were significantly correlated with CP (r > 0.92). Moreover, the highest coefficient of correlation (r=0.71; P < 0.01) between the percentage of maximal aerobic power in cycling that corresponds to a blood lactate concentration of 4 mmol x l(-1) (OBLA%) and the different local aerobic indices was observed with CP.

  16. Differential effects of mercury on activity and swimming endurance in a model aquatic predator-prey system

    SciTech Connect

    Benton, M.J.; Carlson, J.K.; Benson, W.H.

    1994-12-31

    In addition to direct effects of contaminants on organisms, populations and communities, there may also be indirect or secondary effects related to altered behavior. This study examined the effects of mercury exposure on locomotory behavior in a model predator-prey system of largemouth bass (Micropterus salmoides) and fathead minnows (Pimephales promelas). At both low and high mercury concentrations, there was a significant effect of exposure on unforced activity and swimming endurance in fathead minnows. At all tested mercury concentrations, activity and endurance also were both positively correlated to body length. However, largemouth bass unforced activity and swimming endurance were not affected by exposure to low mercury concentrations. In light of these differential locomotory effects at environmentally relevant mercury concentrations, the potential impact on aquatic predator-prey systems will be discussed.

  17. Hydrokinesitherapy program using the Halliwick method on strength endurance and flexibility in a person with poliomyelitis sequelae.

    PubMed

    Ochoa Martínez, Paulina Yesica; Hall Lopez, Javier Arturo; Mateos Valenzuela, Adriana Griselda

    2014-09-12

    This case study attempts to determine the effect of a hydrokinesitherapy program by means of the Halliwick method on physical fitness in a female aged 35 years with poliomyelitis sequelae. The intervention followed sixteen weeks of hydrokinesitherapy during 70 minutes, five times a week, where we carried out exercises from the Halliwick method. There was an assessment both before and after the application. Strength endurance and flexibility were determined according to a senior fitness test protocol. The results showed positive improvements when carrying out the exercises from the Halliwick method and the percentage change (Δ%) of strength endurance increase 361.5% in the right arm and 300% in the left arm. Flexibility increased 2 cm in the right shoulder and 10 cm in the left shoulder. In conclusion the subject was able to improve the performance of Halliwick exercises while showing an increase in strength endurance and flexibility.

  18. Blood Volume: Its Adaptation to Endurance Training

    NASA Technical Reports Server (NTRS)

    Convertino, Victor A.

    1991-01-01

    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.

  19. Effects of submaximal and supramaximal interval training on determinants of endurance performance in endurance athletes.

    PubMed

    Paquette, M; Le Blanc, O; Lucas, S J E; Thibault, G; Bailey, D M; Brassard, P

    2017-03-01

    We compared the effects of submaximal and supramaximal cycling interval training on determinants of exercise performance in moderately endurance-trained men. Maximal oxygen consumption (VO2max ), peak power output (Ppeak ), and peak and mean anaerobic power were measured before and after 6 weeks (3 sessions/week) of submaximal (85% maximal aerobic power [MP], HIIT85 , n = 8) or supramaximal (115% MP, HIIT115 , n = 9) interval training to exhaustion in moderately endurance-trained men. High-intensity training volume was 47% lower in HIIT115 vs HIIT85 (304 ± 77 vs 571 ± 200 min; P < 0.01). Exercise training was generally associated with increased VO2max (HIIT85 : +3.3 ± 3.1 mL/kg/min; HIIT115 : +3.3 ± 3.6 ml/kg/min; Time effect P = 0.002; Group effect: P = 0.95), Ppeak (HIIT85 : +18 ± 9 W; HIIT115 : +16 ± 27 W; Time effect P = 0.045; Group effect: P = 0.49), and mean anaerobic power (HIIT85 : +0.42 ± 0.69 W/kg; HIIT115 : +0.55 ± 0.65 W/kg; Time effect P = 0.01; Group effect: P = 0.18). Six weeks of submaximal and supramaximal interval training performed to exhaustion seems to equally improve VO2max and anaerobic power in endurance-trained men, despite half the accumulated time spent at the target intensity.

  20. Altitude training for elite endurance performance: a 2012 update.

    PubMed

    Fudge, Barry W; Pringle, Jamie S M; Maxwell, Neil S; Turner, Gareth; Ingham, Stephen A; Jones, Andrew M

    2012-01-01

    Altitude training is commonly used by endurance athletes and coaches in pursuit of enhancement of performance on return to sea level. The purpose of the current review article was to update and evaluate recent literature relevant to the practical application of altitude training for endurance athletes. Consequently, the literature can be considered in either of two categories: performance-led investigations or mechanistic advancements/insights. Each section discusses the relevant literature and proposes future directions where appropriate.

  1. The Diurnal Variation on Cardiovascular Endurance Performance of Secondary School Athlete Student

    PubMed Central

    Chin, Chun-Yip; Chow, Gary Chi-Ching; Hung, Kwong-Chung; Kam, Lik-Hang; Chan, Ka-Chun; Mok, Yuen-Ting; Cheng, Nga-Mei

    2015-01-01

    Background: The previous investigations in diurnal variation of endurance sports performance did not reach a consensus and have been limited. This study would be a valuable resource for endurance sports trainers and event managers to plan their training and competition in a specific time of day. Objectives: The aim of this study is to find out the diurnal variation in cardiovascular endurance performance in the young athletes. Materials and Methods: Thirty five athlete students (15.17 ± 1.62 years) participated in this study. Maximal oxygen uptake (VO2max), post-exercise percentage of maximal heart rate (MHR% post-ex), post-exercise body temperature (BTemppost-ex), and post exercise blood lactic acid level (LApost-ex) were measured in this study. Three non-consecutive testings: A) Morning (09:00-10:00; AM), B) Noon (12:00-13:00; NN) and C) Afternoon (16:00-17:00; PM) were conducted. Participants were required to follow the meal plan and resting schedule for all testing days. Results: VO2max was significantly higher at NN (F2. 68 = 3.29, P < 0.05, η2 = 0.088) in comparison with PM. The MHR%post-ex, BTemppost-ex, LApost-ex was not significantly different among three times of day. Conclusions: Diurnal effect on endurance performance was found and the highest exercise VO2max was identified at noon. Secondary school students or young athletes are recommended to have sports training related to VO2max at noon for the purpose of maximizing training effectiveness. PMID:26448833

  2. Master Athletes Are Extending the Limits of Human Endurance

    PubMed Central

    Lepers, Romuald; Stapley, Paul J.

    2016-01-01

    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

  3. Nutrition for endurance sports: marathon, triathlon, and road cycling.

    PubMed

    Jeukendrup, Asker E

    2011-01-01

    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.

  4. Cardiovascular damage resulting from chronic excessive endurance exercise.

    PubMed

    Patil, Harshal R; O'Keefe, James H; Lavie, Carl J; Magalski, Anthony; Vogel, Robert A; McCullough, Peter A

    2012-01-01

    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.

  5. Concurrent strength and endurance training exercise sequence does not affect neuromuscular adaptations in older men.

    PubMed

    Wilhelm, Eurico Nestor; Rech, Anderson; Minozzo, Felipe; Botton, Cintia Ehlers; Radaelli, Regis; Teixeira, Bruno Costa; Reischak-Oliveira, Alvaro; Pinto, Ronei Silveira

    2014-12-01

    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.

  6. The enduring impact of violence against children.

    PubMed

    Hillis, Susan D; Mercy, James A; Saul, Janet R

    2017-04-01

    More than one billion children - half of all children in the world - are exposed to violence every year. The violence children are exposed to includes both direct experiences of physical, sexual, and emotional abuse, as well as indirectly witnessing violence in their homes, schools, and communities. What these various forms of violence share, based on a review of the literature, is their enduring potential for life-long consequences. These consequences include increases in the risks of injury, HIV, sexually transmitted infections, mental health problems, reproductive health problems, and non-communicable diseases, including cardiovascular disease, cancer, chronic lung disease, and diabetes. Studies addressing biologic underpinnings of such consequences demonstrate that violence-associated toxic stress may cause damage to the nervous, endocrine, circulatory, musculo-skeletal, reproductive, respiratory, and immune systems. Furthermore, rigorous economic evaluations suggest that costs associated with the consequences of violence against children exceed $120 billion in the U.S. and account for up to 3.5% of the GDP in sub-regions of East Asia. The expanding literature confirming the mechanisms of consequences and the associated costs of violence against children has been accompanied by growing evidence on effective approaches to prevention. Moreover, the expanding evidence on prevention has been accompanied by a growing determination on the part of global leaders to accelerate action. Thus, as part of the Post-2015 Sustainable Development agenda, the UN has issued a call-to-action: to eliminate violence against children. This unprecedented UN call may foster new investments, to fuel new progress for protecting children around the world from violence and its preventable consequences.

  7. Strength, Endurance, Throwing Velocity and in-Water Jump Performance of Elite German Water Polo Players.

    PubMed

    Zinner, Christoph; Sperlich, Billy; Krueger, Malte; Focke, Tim; Reed, Jennifer; Mester, Joachim

    2015-03-29

    The purpose of this study was threefold: 1) to assess the eggbeater kick and throwing performance using a number of water polo specific tests, 2) to explore the relation between the eggbeater kick and throwing performance, and 3) to investigate the relation between the eggbeater kick in the water and strength tests performed in a controlled laboratory setting in elite water polo players. Fifteen male water polo players of the German National Team completed dynamic and isometric strength tests for muscle groups (adductor, abductor, abdominal, pectoralis) frequently used during water polo. After these laboratory strength tests, six water polo specific in-water tests were conducted. The eggbeater kick assessed leg endurance and agility, maximal throwing velocity and jump height. A 400 m test and a sprint test examined aerobic and anaerobic performance. The strongest correlation was found between jump height and arm length (p < 0.001, r = 0.89). The laboratory diagnostics of important muscles showed positive correlations with the results of the in-water tests (p < 0.05, r = 0.52-0.70). Muscular strength of the adductor, abdominal and pectoralis muscles was positively related to in-water endurance agility as assessed by the eggbeater kick (p < 0.05; r = 0.53-0.66). Findings from the current study emphasize the need to assess indices of water polo performance both in and out of the water as well as the relation among these parameters to best assess the complex profile of water polo players.

  8. Skeletal muscle respiratory capacity, endurance, and glycogen utilization.

    PubMed

    Fitts, R H; Booth, F W; Winder, W W; Holloszy, J O

    1975-04-01

    This study was undertaken to evaluate the relationship between physical performance capacity and the mitochondrial content of skeletal muscle. Four groups of rats were trained by means of treadmill running 5 days/wk for 13 wk. One group ran 10 min/day, a second group ran 30 min/day, a third group ran 60 min/day, and a fourth group ran 120 min/day. The magnitude of the exercise-induced adaptive increase in gastrocnemius muscle respiratory capacity varied over a twofold range in the four groups. There were significant correlations between the levels of three mitochondrial markers (cytochrome c, citrate synthase, respiratory capacity) in the animals' gastrocnemius muscles and the duration of a run to exhaustion. There was also a significant correlation between the amounts of glycogen remaining in liver and skeletal muscle after a 30-min-long exercise test and the respiratory capacity of the animal's leg muscles. These findings are compatible with the interpretation that a close relationshiop exists between skeletal muscle mitochondrial content and the capacity to perform endurance exercise.

  9. The role of back muscle endurance, maximum force, balance and trunk rotation control regarding lifting capacity.

    PubMed

    Schenk, Peter; Klipstein, Andreas; Spillmann, Susanne; Strøyer, Jesper; Laubli, Thomas

    2006-01-01

    Evaluation of lifting capacity is widely used as a reliable instrument in order to evaluate maximal and safe lifting capacity. This is of importance in regard to planning rehabilitation programs and determining working ability. The aim of this study was to investigate the influence of basic functions on the lifting capacity measured by the progressive isoinertial lifting evaluation (PILE) and the functional capacity evaluation (FCE) tests in a lower (floor to waist) and an upper (waist to shoulder) setting and compare the two test constructs. Seventy-four female subjects without acute low back pain underwent an examination of their lifting capacities and the following basic functions: (1) strength and endurance of trunk muscles, (2) cardiovascular endurance, (3) trunk mobility and (4) coordination ability. A linear regression model was used to predict lifting capacity by means of the above-mentioned basic functions, where the F statistics of the variables had to be significant at the 0.05 level to remain in the model. Maximal force in flexion showed significant influence on the lifting capacity in both the PILE and the FCE in the lower, as well as in the upper, lifting task. Furthermore, there was a significant influence of cardiovascular endurance on the lower PILE and also of endurance in trunk flexion on the lower FCE. Additional inclusion of individual factors (age, height, weight, body mass index) into the regression model showed a highly significant association between body height and all lifting tasks. The r (2) of the original model used was 0.19/0.18 in the lower/upper FCE and 0.35/0.26 in the lower/upper PILE. The model r (2) increased after inclusion of these individual factors to between 0.3 and 0.4. The fact that only a limited part of the variance in the lifting capacities can be explained by the basic functions analyzed in this study confirms the assumption that factors not related to the basic functions studied, such as lifting technique and motor

  10. Carry-over effects of music in an isometric muscular endurance task.

    PubMed

    Crust, Lee

    2004-06-01

    This study tested the effects of exposure to self-selected motivational music both prior to and during performance of a muscular endurance task. 27 male undergraduate students in sports science completed an isometric weight-holding task on two separate occasions while listening either to self-selected motivational music or white noise. Participants were assigned to one of three groups on the basis of scores on a familiarization trial. The three groups were Prior Exposure, music or white noise played immediately before task commencement; Half Exposure, conditions initiated simultaneously with task commencement but terminated approximately half-way through the trial; and Full Exposure, conditions initiated simultaneously with trial commencement and continuing until voluntary cessation. A two-way mixed-model analysis of variance yielded a significant interaction and a main effect for condition. Participants held the weight suspended significantly longer when listening to music than with white noise. For the interaction, analysis of gain scores indicated participants' performance increased more for exposure to music during the entire session, than for exposure to music prior to the session. These results suggest that exposure to music during muscular endurance trials can yield significantly longer endurance times, but that exposure to music prior to task commencement may not carry over to influence performance.

  11. Physical growth and changes in intermittent endurance run performance in young male Basque soccer players.

    PubMed

    Carvalho, Humberto M; Bidaurrazaga-Letona, Iraia; Lekue, José António; Amado, Markos; Figueiredo, António J; Gil, Susana M

    2014-01-01

    The present 4-year longitudinal study examined physical growth and development of intermittent endurance run performance in young Basque soccer players aged 10-15 years applying multilevel regression modeling. Anthropometry, predicted adult stature and Yo-Yo Intermittent Recovery level 1 test (Yo-Yo IR1) of players from the under-11 teams from the Athletic Club of Bilbao were measured at pre- and end-season (two measurements per year of study, n = 33 considered for analysis). A non-linear effect of age on intermittent endurance run was observed, with significantly higher increases in Yo-Yo IR1 between 10-11 year-old and 14-15 year-old players. The development of Yo-Yo IR1 performance in all the years of the study was influenced positively by training exposure during the seasons (P < 0.01) and independent of maturity status and body size (P > 0.05). The steady development of intermittent endurance run performance during pubertal years in adolescent Basque soccer players is partially influenced by training exposure.

  12. Muscular endurance repetitions to predict bench press strength in men of different training levels.

    PubMed

    Mayhew, J L; Prinster, J L; Ware, J S; Zimmer, D L; Arabas, J R; Bemben, M G

    1995-06-01

    The purpose of this study was to determine the accuracy of predicting maximal bench press (BP) strength (1-RM) from relative endurance performance in various groups of men. The subjects included untrained students (n = 35), resistance trained students (n = 28), college wrestlers (n = 21), soccer players (n = 22), football players (n = 51), high school students (n = 35), and resistance-trained middle-aged men (n = 24). Each subject performed a 1-RM test according to the same standard procedure. Within 4-10 days, the subject selected a weight to perform as many repetitions as possible to failure. Six relative endurance prediction equations produced validity coefficients of r = 0.86 to 0.98 in each group and r = 0.82 to 0.98 in the composite group (n = 220). In subjects completing < or = 10 repetitions-to-failure, three equations significantly overpredicted and two significantly underpredicted 1-RM scores. The Brzycki equation was the most accurate. In subjects completing > 10 repetitions to failure, three equations significantly overpredicted and three significantly underpredicted 1-RM scores. While caution should be used when employing relative muscular endurance performance to estimate 1-RM strength in the bench press, the average of two equations may reduce the error.

  13. Respiratory muscle endurance is limited by lower ventilatory efficiency in post-myocardial infarction patients

    PubMed Central

    Neves, Laura M. T.; Karsten, Marlus; Neves, Victor R.; Beltrame, Thomas; Borghi-Silva, Audrey; Catai, Aparecida M.

    2014-01-01

    Background Reduced respiratory muscle endurance (RME) contributes to increased dyspnea upon exertion in patients with cardiovascular disease. Objective The objective was to characterize ventilatory and metabolic responses during RME tests in post-myocardial infarction patients without respiratory muscle weakness. Method Twenty-nine subjects were allocated into three groups: recent myocardial infarction group (RG, n=9), less-recent myocardial infarction group (LRG, n=10), and control group (CG, n=10). They underwent two RME tests (incremental and constant pressure) with ventilatory and metabolic analyses. One-way ANOVA and repeated measures one-way ANOVA, both with Tukey post-hoc, were used between groups and within subjects, respectively. Results Patients from the RG and LRG presented lower metabolic equivalent and ventilatory efficiency than the CG on the second (50± 06, 50± 5 vs. 42± 4) and third part (50± 11, 51± 10 vs. 43± 3) of the constant pressure RME test and lower metabolic equivalent during the incremental pressure RME test. Additionally, at the peak of the incremental RME test, RG patients had lower oxygen uptake than the CG. Conclusions Post-myocardial infarction patients present lower ventilatory efficiency during respiratory muscle endurance tests, which appears to explain their inferior performance in these tests even in the presence of lower pressure overload and lower metabolic equivalent. PMID:24675907

  14. Arctigenin enhances swimming endurance of sedentary rats partially by regulation of antioxidant pathways

    PubMed Central

    Wu, Ruo-ming; Sun, Yan-yan; Zhou, Ting-ting; Zhu, Zhi-yuan; Zhuang, Jing-jing; Tang, Xuan; Chen, Jing; Hu, Li-hong; Shen, Xu

    2014-01-01

    Aim: Arctigenin, a phenylpropanoid dibenzylbutyrolactone lignan found in traditional Chinese herbs, has been determined to exhibit a variety of pharmacological activities, including anti-tumor, anti-inflammation, neuroprotection, and endurance enhancement. In the present study, we investigated the antioxidation and anti-fatigue effects of arctigenin in rats. Methods: Rat L6 skeletal muscle cell line was exposed to H2O2 (700 μmol/L), and ROS level was assayed using DCFH-DA as a probe. Male SD rats were injected with arctigenin (15 mg·kg−1·d−1, ip) for 6 weeks, and then the weight-loaded forced swimming test (WFST) was performed to evaluate their endurance. The levels of antioxidant-related genes in L6 cells and the skeletal muscles of rats were analyzed using real-time RT-PCR and Western blotting. Results: Incubation of L6 cells with arctigenin (1, 5, 20 μmol/L) dose-dependently decreased the H2O2-induced ROS production. WFST results demonstrated that chronic administration of arctigenin significantly enhanced the endurance of rats. Furthermore, molecular biology studies on L6 cells and skeletal muscles of the rats showed that arctigenin effectively increased the expression of the antioxidant-related genes, including superoxide dismutase (SOD), glutathione reductase (Gsr), glutathione peroxidase (GPX1), thioredoxin (Txn) and uncoupling protein 2 (UCP2), through regulation of two potential antioxidant pathways: AMPK/PGC-1α/PPARα in mitochondria and AMPK/p53/Nrf2 in the cell nucleus. Conclusion: Arctigenin efficiently enhances rat swimming endurance by elevation of the antioxidant capacity of the skeletal muscles, which has thereby highlighted the potential of this natural product as an antioxidant in the treatment of fatigue and related diseases. PMID:25152028

  15. Increased intramuscular lipid synthesis and low saturation relate to insulin sensitivity in endurance-trained athletes.

    PubMed

    Bergman, Bryan C; Perreault, Leigh; Hunerdosse, Devon M; Koehler, Mary C; Samek, Ali M; Eckel, Robert H

    2010-05-01

    Intramuscular triglyceride (IMTG) has received considerable attention as a potential mechanism promoting insulin resistance. Endurance-trained athletes have high amounts of IMTG but are insulin sensitive, suggesting IMTG content alone does not change insulin action. Recent data suggest increased muscle lipid synthesis protects against fat-induced insulin resistance. We hypothesized that rates of IMTG synthesis at rest would be increased in athletes compared with controls. Eleven sedentary men and 11 endurance-trained male cyclists participated in this study. An intravenous glucose tolerance test was performed to assess insulin action. After 3 days of dietary control and an overnight fast, [13C16]palmitate was infused at 0.0174 micromol.kg(-1).min(-1) for 4 h, followed by a muscle biopsy to measure isotope incorporation into IMTG and diacylglycerol. Compared with controls, athletes were twice as insulin sensitive (P=0.004) and had a significantly greater resting IMTG concentration (athletes: 20.4+/-1.6 microg IMTG/mg dry wt, controls: 14.5+/-1.8 microg IMTG/mg dry wt, P=0.04) and IMTG fractional synthesis rate (athletes: 1.56+/-0.37%/h, controls: 0.61+/-0.15%/h, P=0.03). Stearoyl-CoA desaturase 1 mRNA expression (P=0.02) and protein content (P=0.03) were also significantly greater in athletes. Diacylglycerol, but not IMTG, saturation was significantly less in athletes compared with controls (P=0.002). These data indicate endurance-trained athletes have increased synthesis rates of skeletal muscle IMTG and decreased saturation of skeletal muscle diacylglycerol. Increased synthesis rates are not due to recovery from exercise and are likely adaptations to chronic endurance exercise training.

  16. Effects of heat acclimation on endurance capacity and prolactin response to exercise in the heat.

    PubMed

    Burk, Andres; Timpmann, Saima; Kreegipuu, Kairi; Tamm, Maria; Unt, Eve; Oöpik, Vahur

    2012-12-01

    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.

  17. Ability of clinicopathologic variables and clinical examination findings to predict race elimination in endurance horses.

    PubMed

    Fielding, C Langdon; Meier, Chloe A; Fellers, Greg K; Magdesian, K Gary

    2017-01-01

    OBJECTIVE To compare results of point-of-care laboratory testing with standard veterinary clinical examination findings at a single time point during endurance competition to identify horses at risk for elimination. ANIMALS 101 endurance horses participating in the 2013 Western States 160-km (100-mile) endurance ride. PROCEDURES At the 58-km checkpoint, blood samples were collected from all horses. Samples were analyzed for pH, Pco2, base excess, anion gap, PCV, and whole blood concentrations of sodium, potassium, chloride, total carbon dioxide, BUN, glucose, and bicarbonate. Corrected electrolyte and PCV values were calculated on the basis of plasma total protein concentration. Immediately following the blood sample collection, each horse underwent a clinical examination. In addition to standard examination variables, an adjusted heart rate was calculated on the basis of the variable interval between entry into the checkpoint and heart rate recording. A combination of stepwise logistic regression, classification and regression tree analysis, and generalized additive models was used to identify variables that were associated with overall elimination or each of 3 other elimination categories (metabolic elimination, lameness elimination, and elimination for other reasons). RESULTS Corrected whole blood potassium concentration and adjusted heart rate were predictive for overall elimination. Breed, plasma total protein concentration, and attitude were predictive for elimination due to metabolic causes. Whole blood chloride concentration and corrected PCV were predictive for elimination due to lameness. Corrected PCV was predictive for elimination due to other causes. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that for horses in endurance competition, a combination of breed and clinical examination and laboratory variables provided the best prediction of overall elimination.

  18. Acute arginine supplementation fails to improve muscle endurance or affect blood pressure responses to resistance training.

    PubMed

    Greer, Beau K; Jones, Brett T

    2011-07-01

    Dietary supplement companies claim that arginine supplements acutely enhance skeletal muscular endurance. The purpose of this study was to determine whether acute arginine α-ketoglutarate supplementation (AAKG) will affect local muscle endurance of the arm and shoulder girdle or the blood pressure (BP) response to anaerobic exercise. Twelve trained college-aged men (22.6 ± 3.8 years) performed 2 trials of exercise separated by at least 1 week. At 4 hours before, and 30 minutes before exercise, a serving of an AAKG supplement (3,700 mg arginine alpha-ketoglutarate per serving) or placebo was administered. Resting BP was assessed pre-exercise after 16 minutes of seated rest, and 5 and 10 minutes postexercise. Three sets each of chin-ups, reverse chin-ups, and push-ups were performed to exhaustion with 3 minutes of rest between each set. Data were analyzed using repeated-measures analysis of variance and paired t-tests. The AAKG supplementation did not improve muscle endurance or significantly affect the BP response to anaerobic work. Subjects performed fewer total chin-ups (23.75 ± 6.38 vs. 25.58 ± 7.18) and total trial repetitions (137.92 ± 28.18 vs. 141.08 ± 28.57) in the supplement trial (p ≤ 0.05). Subjects executed fewer reverse chin-ups (5.83 ± 1.85 vs. 6.75 ± 2.09) during set 2 after receiving the supplement as compared to the placebo (p < 0.05). Because AAKG supplementation may hinder muscular endurance, the use of these supplements before resistance training should be questioned.

  19. Endurance training enhances vasodilation induced by nitric oxide in human skin.

    PubMed

    Boegli, Yann; Gremion, Gerald; Golay, Sandrine; Kubli, Sandrine; Liaudet, Lucas; Leyvraz, Pierre-François; Waeber, Bernard; Feihl, François

    2003-11-01

    Endurance training modifies the thermoregulatory control of skin blood flow, as manifested by a greater augmentation of skin perfusion for the same increase in core temperature in athletes, in comparison with sedentary subjects. In this study, we tested the hypothesis that a component of this adaptation might reside in a higher ability of cutaneous blood vessels to respond to vasodilatory stimuli. We recruited healthy nonsmoking males, either endurance trained or sedentary, in two different age ranges (18-35 y and >50 y). Skin blood flow was measured in the forearm skin, using a laser Doppler imager, allowing to record the vasodilatory responses to the following stimuli: iontophoresis of acetylcholine (an endothelium-dependent vasodilator), iontophoresis of sodium nitroprusside (a nitric oxide donor), and release of a temporary interruption of arterial inflow (reactive hyperemia). There was no effect of training on reactive hyperemia or the response to acetylcholine. In contrast, the increase in perfusion following the iontophoresis of sodium nitroprusside, expressed in perfusion units, was larger in trained than in sedentary subjects (younger: 398 +/- 54 vs 350 +/- 87, p < 0.05; older 339 +/- 72 vs 307 +/- 66, p < 0.05). In conclusion, endurance training enhances the vasodilatory effects of nitric oxide in the human dermal microcirculation, at least in forearm skin. These observations have considerable physiologic interest in view of recent data indicating that nitric oxide mediates in part the cutaneous vasodilation induced by heat stress in humans. Therefore, the augmentation of nitric oxide bioactivity in the dermal microcirculation might be one mechanism whereby endurance training modifies the thermoregulatory control of skin blood flow.

  20. Caffeine and exercise: metabolism, endurance and performance.

    PubMed

    Graham, T E

    2001-01-01

    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

  1. β-alanine supplementation improves isometric endurance of the knee extensor muscles

    PubMed Central

    2012-01-01

    Background We examined the effect of four weeks of β-alanine supplementation on isometric endurance of the knee extensors at 45% maximal voluntary isometric contraction (MVIC). Methods Thirteen males (age 23 ± 6 y; height 1.80 ± 0.05 m; body mass 81.0 ± 10.5 kg), matched for pre-supplementation isometric endurance, were allocated to either a placebo (n = 6) or β-alanine (n = 7; 6.4 g·d-1 over 4 weeks) supplementation group. Participants completed an isometric knee extension test (IKET) to fatigue, at an intensity of 45% MVIC, before and after supplementation. In addition, two habituation tests were completed in the week prior to the pre-supplementation test and a further practice test was completed in the week prior to the post-supplementation test. MVIC force, IKET hold-time, and impulse generated were recorded. Results IKET hold-time increased by 9.7 ± 9.4 s (13.2%) and impulse by 3.7 ± 1.3 kN·s-1 (13.9%) following β-alanine supplementation. These changes were significantly greater than those in the placebo group (IKET: t(11) = 2.9, p ≤0.05; impulse: t(11) = 3.1, p ≤ 0.05). There were no significant changes in MVIC force in either group. Conclusion Four weeks of β-alanine supplementation at 6.4 g·d-1 improved endurance capacity of the knee extensors at 45% MVIC, which most likely results from improved pH regulation within the muscle cell as a result of elevated muscle carnosine levels. PMID:22697405

  2. Satellite cell response to erythropoietin treatment and endurance training in healthy young men

    PubMed Central

    Hoedt, Andrea; Christensen, Britt; Nellemann, Birgitte; Mikkelsen, Ulla Ramer; Hansen, Mette; Schjerling, Peter

    2016-01-01

    and active SCs (Pax7+/MyoD+). ESA treatment led to elevated haematocrit, whereas endurance training increased V˙O2, max . Endurance training led to an increase in SCs associated with type II fibres (P < 0.05), whereas type I fibres showed no changes. Both ESA treatment and endurance training increased Pax7+/MyoD+ cells, whereas only ESA treatment increased the total content of MyoD+ cells. Epo‐R mRNA presence in adult SC was tested with real‐time RT‐PCR using fluorescence‐activated cell sorting (CD56+/CD45−/CD31−) to isolate cells from a human rectus abdominis muscle and was found to be considerably higher than in whole muscle. In conclusion, endurance training and ESA treatment may separately stimulate SC commitment to the myogenic program. Furthermore, ESA‐treatment may alter SC activity by direct interaction with the Epo‐R expressed on SCs. PMID:26607845

  3. Creatine supplementation enhances endurance performance in trained rats.

    PubMed

    Malin, Steven K; Cotugna, Nancy

    2008-01-01

    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.

  4. Endurance training: is it bad for you?

    PubMed Central

    Gruttad’Auria, Claudia I.; Baiamonte, Pierpaolo; Mazzuca, Emilia; Castrogiovanni, Alessandra; Bonsignore, Maria R.

    2016-01-01

    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

  5. Short-term effect of crunch exercise frequency on abdominal muscle endurance.

    PubMed

    Juan-Recio, C; López-Vivancos, A; Moya, M; Sarabia, J M; Vera-Garcia, F J

    2015-04-01

    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.

  6. Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans.

    PubMed

    Burgomaster, Kirsten A; Hughes, Scott C; Heigenhauser, George J F; Bradwell, Suzanne N; Gibala, Martin J

    2005-06-01

    Parra et al. (Acta Physiol. Scand 169: 157-165, 2000) showed that 2 wk of daily sprint interval training (SIT) increased citrate synthase (CS) maximal activity but did not change "anaerobic" work capacity, possibly because of chronic fatigue induced by daily training. The effect of fewer SIT sessions on muscle oxidative potential is unknown, and aside from changes in peak oxygen uptake (Vo(2 peak)), no study has examined the effect of SIT on "aerobic" exercise capacity. We tested the hypothesis that six sessions of SIT, performed over 2 wk with 1-2 days rest between sessions to promote recovery, would increase CS maximal activity and endurance capacity during cycling at approximately 80% Vo(2 peak). Eight recreationally active subjects [age = 22 +/- 1 yr; Vo(2 peak) = 45 +/- 3 ml.kg(-1).min(-1) (mean +/- SE)] were studied before and 3 days after SIT. Each training session consisted of four to seven "all-out" 30-s Wingate tests with 4 min of recovery. After SIT, CS maximal activity increased by 38% (5.5 +/- 1.0 vs. 4.0 +/- 0.7 mmol.kg protein(-1).h(-1)) and resting muscle glycogen content increased by 26% (614 +/- 39 vs. 489 +/- 57 mmol/kg dry wt) (both P < 0.05). Most strikingly, cycle endurance capacity increased by 100% after SIT (51 +/- 11 vs. 26 +/- 5 min; P < 0.05), despite no change in Vo(2 peak). The coefficient of variation for the cycle test was 12.0%, and a control group (n = 8) showed no change in performance when tested approximately 2 wk apart without SIT. We conclude that short sprint interval training (approximately 15 min of intense exercise over 2 wk) increased muscle oxidative potential and doubled endurance capacity during intense aerobic cycling in recreationally active individuals.

  7. Effects of yoga practice on muscular endurance in young women.

    PubMed

    Shiraishi, Juliana Costa; Bezerra, Lídia Mara Aguiar

    2016-02-01

    The aim of this study was to verify the effects of a systematized yoga practice on muscular endurance in young women. Twenty six women (24 ± 3.5 years old) participated in six weeks of yoga classes, and twenty one women (25 ± 5.1 years old) participated as the control group. The yoga intervention was composed of eighteen sessions, three times per week, at 1 h per session. The muscular endurance of upper limbs (push-up) and abdominal (sit-up) was assessed through the protocol suggested by Gettman (1989) [1] and Golding, Myers and Sinning (1989) [2] to the maximum repetitions performed in 1 min. To verify the significant differences intra groups and between groups a SPANOVA was performed, and the level of significance was p ≤ 0.05. The findings suggest that yoga provides improvement in upper limb and in abdominal muscular endurance.

  8. Effects of excessive endurance activity on the heart.

    PubMed

    Seidl, Jamie; Asplund, Chad A

    2014-01-01

    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.

  9. Assessment of the effects of eleutherococcus senticosus on endurance performance.

    PubMed

    Goulet, Eric D B; Dionne, Isabelle J

    2005-02-01

    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.

  10. Pilates for improvement of muscle endurance, flexibility, balance, and posture.

    PubMed

    Kloubec, June A

    2010-03-01

    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.

  11. Mixed maximal and explosive strength training in recreational endurance runners.

    PubMed

    Taipale, Ritva S; Mikkola, Jussi; Salo, Tiina; Hokka, Laura; Vesterinen, Ville; Kraemer, William J; Nummela, Ari; Häkkinen, Keijo

    2014-03-01

    Supervised periodized mixed maximal and explosive strength training added to endurance training in recreational endurance runners was examined during an 8-week intervention preceded by an 8-week preparatory strength training period. Thirty-four subjects (21-45 years) were divided into experimental groups: men (M, n = 9), women (W, n = 9), and control groups: men (MC, n = 7), women (WC, n = 9). The experimental groups performed mixed maximal and explosive exercises, whereas control subjects performed circuit training with body weight. Endurance training included running at an intensity below lactate threshold. Strength, power, endurance performance characteristics, and hormones were monitored throughout the study. Significance was set at p ≤ 0.05. Increases were observed in both experimental groups that were more systematic than in the control groups in explosive strength (12 and 13% in men and women, respectively), muscle activation, maximal strength (6 and 13%), and peak running speed (14.9 ± 1.2 to 15.6 ± 1.2 and 12.9 ± 0.9 to 13.5 ± 0.8 km Ł h). The control groups showed significant improvements in maximal and explosive strength, but Speak increased only in MC. Submaximal running characteristics (blood lactate and heart rate) improved in all groups. Serum hormones fluctuated significantly in men (testosterone) and in women (thyroid stimulating hormone) but returned to baseline by the end of the study. Mixed strength training combined with endurance training may be more effective than circuit training in recreational endurance runners to benefit overall fitness that may be important for other adaptive processes and larger training loads associated with, e.g., marathon training.

  12. The Research on the Effect of the Food with Different Glycaemic Index and Glycaemic Load on the Immunity of Endurance Athletes

    PubMed Central

    Li, Dongmei

    2015-01-01

    For studying the effect of eating the food containing carbohydrates with different glycaemic index and glycaemic load 2 hours before athletics on the exercise tolerance and immune function, select 10 men long-distance endurance athletes, use not completely random balance repeated testing methods, randomized complete the three endurance tests. And each test interval is not less than seven days. The results suggest that there is no apparent effect of eating the food containing carbohydrates with different glycaemic index and glycaemic load 2 hours before athletics on the exercise tolerance and immune function. Compared with the glycaemic index and glycaemic load of food, the carbohydrate content of the diet before athletics may be the more important factor affecting the immune response in endurance sports. PMID:26998178

  13. Combined lower body endurance and upper body resistance training improves performance and health parameters in healthy active elderly.

    PubMed

    Verney, Julien; Kadi, Fawzi; Saafi, Mohamed A; Piehl-Aulin, Karin; Denis, Christian

    2006-06-01

    We investigated the effects of combined lower body (LB) endurance and upper body (UB) resistance training on endurance, strength, blood lipid profile and body composition in active older men. Ten healthy still active men (73+/-4 years, V(O2) peak: 36 (31-41) ml min-1 kg-1) were tested before and after 14 weeks of combined training (3 times week-1). Training consisted of 3x12 min of high intensity interval training on a bicycle for endurance interspersed by 3x12 min of UB resistance exercises. V(O2) peak during leg cycling and arm cranking, isokinetic torque of knee extensor and shoulder abductor and the cross-sectional area (CSA) of several muscles from UB and LB were measured. Sagittal abdominal diameter (SAD) and abdominal fat area were measured on MRI scans. Total body composition was assessed by hydrostatic weighing (HW) and dual-energy X-ray absorptiometry (DEXA). Blood lipid profile was assessed before and after training. By the end of the training period, V(O2) peak (l min-1) increased significantly by 9 and 16% in leg cycling and arm cranking tests, respectively. Maximal isokinetic torque increased both for the knee extensor and shoulder abductor muscle groups. CSA increased significantly in deltoid muscle. Percentage of body fat decreased by 1.3% (P<0.05) and abdominal fat and SAD decreased by 12 and 6%, respectively (P<0.01). There was also a significant decrease in total cholesterol and low-density lipoprotein. Thus, combined LB endurance and UB resistance training can improve endurance, strength, body composition and blood lipid profile even in healthy active elderly.

  14. The kinanthropometric and pulmonary determinants of global respiratory muscle strength and endurance indices in an athletic population.

    PubMed

    Kroff, Jacolene; Terblanche, Elmarie

    2010-09-01

    The morphological determinants of respiratory muscle (RM) strength and endurance in non-athletic populations are well documented, but are lacking in athletic populations. The purpose of this study was to determine the kinanthropometric and pulmonary predictors of RM strength and endurance. 160 athletes (103 men) were recruited from eight different sports to participate in the study. All subjects underwent a series of kinanthropometric and RM function assessments during a single visit to the laboratory. RM function assessments included the flow-volume curve test to assess pulmonary function, maximum voluntary ventilation (MVV) to assess RM endurance and maximum inspiratory mouth pressure (MIP) and maximum expiratory mouth pressure (MEP) to assess RM strength. Multiple regression analyses revealed that gender, mesomorphy and exercise sessions per week predicted 35% (SEE = 26.6 cmH(2)O) of the variance in inspiratory muscle strength (MIP). Gender and mesomorphy predicted 24% (SEE = 28.3 cmH(2)O) of the variance in expiratory muscle strength (MEP), while gender, relative sitting height, forced expiratory volume in 1 s (FEV(1)) and peak expiratory flow rate (PEFR) predicted 78% (SEE = 18.2 L min(-1)) of the variance in RM endurance (MVV). Although the reference equations are still not adequate to predict MIP and MEP in an athletic population, they provide more suitable reference values than previously reported. The predicted values derived from the equation for MVV can be applied as adequate reference values for athletic populations.

  15. A six-week trial of hula hooping using a weighted hoop: effects on skinfold, girths, weight, and torso muscle endurance.

    PubMed

    McGill, Stuart M; Cambridge, Edward D J; Andersen, Jordan T

    2015-05-01

    Novel ideas for core endurance training are continually being created. However, studies of their mechanism of action assist in evaluation of their potential as a training tool, for a variety of people and purposes. The specific purpose of this study was to evaluate a weighted hula hooping training program for its efficacy on improving core muscular endurance and influence on measures of body composition. Eighteen women participated in a weighted hula hooping trial lasting 6 weeks, although only 13 returned for posttrial re-assessment. Hip and waist circumferences, 5 torso muscle endurance tests, and 5 skinfold measurements ("sum of 5") were measured before and after the exercise program. Paired samples t-tests were performed to examine pre/post changes. On average, participants experienced a significant decrease in waist and hip circumference -3.4 cm (p < 0.01) and -1.4 cm (p ≤ 0.05), respectively and waist-to-hip ratio from 89.3 cm down to 87.3 cm (t = 3.312, p < 0.01). There were no significant changes in torso muscular endurance after the 6 weeks of hooping; however, the average "sum of 5" skinfold measurements increased by 10.5 cm (p ≤ 0.05). This study of weighted hula hooping suggested that regular hooping was associated with reduced waist and hip girth together with a redistribution of body mass; however, there were no improvements in torso muscular endurance as measured by isometric testing.

  16. Effects of combined strength and endurance training on treadmill load carrying walking performance in aging men.

    PubMed

    Holviala, Jarkko; Häkkinen, Arja; Karavirta, Laura; Nyman, Kai; Izquierdo, Mikel; Gorostiaga, Esteban M; Avela, Janne; Korhonen, Janne; Knuutila, Veli-Pekka; Kraemer, William J; Häkkinen, Keijo

    2010-06-01

    The present study examined the effects of twice weekly total body strength training (ST), endurance cycling (ET), and combined ST and ET (2+2 times a week) (SET) training on the load carrying walking test performance on the treadmill (TM) and changes in neuromuscular and endurance performance during a 21-week training period in aging men. Forty healthy men (54.8+/-8.0 years) were divided into 3 training groups (ET n=9, ST n=11, SET n=11) and a control group (C, n=9). Peak oxygen uptake (VO2peak), heart rate, and blood lactate concentration were measured before and after a 21-week training program using a graded TM and maximal incremental bicycle ergometer (BE) tests. Isometric forces, vertical jump, and electromyographic activity of leg extensor and/or forearm flexor (F) muscles were measured before and after training and the TM tests. Increases of 20-21% in strength and of 7-12% in cycling BE VO2peak occurred in the training groups, whereas the changes of C remained minor. VO2peak was associated, both before and after training, with TM exercise time in all groups (from r=0.65, p=0.030 to r=0.93, p<0.001). Only SET showed a significant training-induced increase (p=0.011) in exercise time of the TM walking with no significant increase in TM VO2peak. The present data suggest that in older men ET and SET induced specific increases in BE VO2peak and ST and SET in strength. However, only SET increased walking exercise time indicating improved load carrying walking performance because of large individual differences in the magnitude of the development of either strength or endurance capacities.

  17. Effects of caloric restriction and overnight fasting on cycling endurance performance.

    PubMed

    Ferguson, Lisa M; Rossi, Kelly A; Ward, Emily; Jadwin, Emily; Miller, Todd A; Miller, Wayne C

    2009-03-01

    In addition to aerobic endurance and anaerobic capacity, high power-to-weight ratio (PWR) is important for cycling performance. Cyclists often try to lose weight before race season to improve body composition and optimize PWR. Research has demonstrated body fat-reducing benefits of exercise after fasting overnight. We hypothesized that fasted-state exercise in calorie-restricted trained cyclists would not result in performance decrements and that their PWR would improve significantly. We also hypothesized that substrate use during fasted-state submaximal endurance cycling would shift to greater reliance on fat. Ten trained, competitive cyclists completed a protocol consisting of baseline testing, 3 weeks of caloric restriction (CR), and post-CR testing. The testing sessions measured pre- and post-CR values for resting metabolic rate (RMR), body composition, VO2, PWR and power-to-lean weight ratio (PLWR), and power output, as well as 2-hour submaximal cycling performance, rating of perceived exertion (RPE), and respiratory exchange ratio (RER). There were no significant differences between baseline and post-CR for submaximal trial RER, power output, VO2, RMR, VO2max, or workload at VO2max. However, RPE was significantly lower, and PWR was significantly higher post-CR, whereas RER did not change. The cyclists' PWR and body composition improved significantly, and their overall weight, fat weight, and body fat percentage decreased. Lean mass was maintained. The cyclists' RPE decreased significantly during 2 hours of submaximal cycling post-CR, and there was no decrement in submaximal or maximal cycling performance after 3 weeks of CR combined with overnight fasting. Caloric restriction (up to 40% for 3 weeks) and exercising after fasting overnight can improve a cyclist's PWR without compromising endurance cycling performance.

  18. Correlating Multimodal Physical Sensor Information with Biological Analysis in Ultra Endurance Cycling

    PubMed Central

    May, Gregory C.; Doherty, Aiden R.; Smeaton, Alan F.; Warrington, Giles D.

    2010-01-01

    The sporting domain has traditionally been used as a testing ground for new technologies which subsequently make their way into the public domain. This includes sensors. In this article a range of physical and biological sensors deployed in a 64 hour ultra-endurance non-stop cycling race are described. A novel algorithm to estimate the energy expenditure while cycling and resting during the event are outlined. Initial analysis in this noisy domain of “sensors in the field” are very encouraging and represent a first with respect to cycling. PMID:22163600

  19. Small UAV Research and Evolution in Long Endurance Electric Powered Vehicles

    NASA Technical Reports Server (NTRS)

    Logan, Michael J.; Chu, Julio; Motter, Mark A.; Carter, Dennis L.; Ol, Michael; Zeune, Cale

    2007-01-01

    This paper describes recent research into the advancement of small, electric powered unmanned aerial vehicle (UAV) capabilities. Specifically, topics include the improvements made in battery technology, design methodologies, avionics architectures and algorithms, materials and structural concepts, propulsion system performance prediction, and others. The results of prototype vehicle designs and flight tests are discussed in the context of their usefulness in defining and validating progress in the various technology areas. Further areas of research need are also identified. These include the need for more robust operating regimes (wind, gust, etc.), and continued improvement in payload fraction vs. endurance.

  20. Differences in muscle mechanical properties between elite power and endurance athletes: a comparative study.

    PubMed

    Loturco, Irineu; Gil, Saulo; Laurino, Cristiano Frota de Souza; Roschel, Hamilton; Kobal, Ronaldo; Cal Abad, Cesar C; Nakamura, Fabio Y

    2015-06-01

    performance. The power group presented better performance in vertical jumps, supporting the validity of these tests to distinguish between endurance and power athletes. Furthermore, TMG can discriminate the "athlete-type" using noninvasive indices moderately correlated with explosive lower-body performance. In summary, both vertical jump and TMG assessments could be useful in identifying and selecting young athletes.

  1. 4 Types of Exercise, Endurance | NIH MedlinePlus the Magazine

    MedlinePlus

    ... 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 ...

  2. Recommendations for Healthy Nutrition in Female Endurance Runners: An Update

    PubMed Central

    Deldicque, Louise; Francaux, Marc

    2015-01-01

    The purpose of this review is to present the basic principles of a healthy nutrition in female endurance runner enriched by the latest scientific recommendations. Female endurance runners are a specific population of athletes who need to take specifically care of daily nutrition due to the high load of training and the necessity to keep a rather low body mass. This paradoxical situation can create some nutritional imbalances and deficiencies. Female endurance athletes should pay attention to their total energy intake, which is often lower than their energy requirement. The minimal energy requirement has been set to 45 kcal/kg fat free mass/day plus the amount of energy needed for physical activity. The usual recommended amount of 1.2–1.4 g protein/kg/day has recently been questioned by new findings suggesting that 1.6 g/kg/day would be more appropriate for female athletes. Although a bit less sensitive to carbohydrate loading than their male counterparts, female athletes can benefit from this nutritional strategy before a race if the amount of carbohydrates reaches 8 g/kg/day and if their daily total energy intake is sufficient. A poor iron status is a common issue in female endurance runners but iron-enriched food as well as iron supplementation may help to counterbalance this poor status. Finally, they should also be aware that they may be at risk for low calcium and vitamin D levels. PMID:26075206

  3. Exercise-Associated Collapse in Endurance Events: A Classification System.

    ERIC Educational Resources Information Center

    Roberts, William O.

    1989-01-01

    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)

  4. Merlin C. Wittrock's Enduring Contributions to the Science of Learning

    ERIC Educational Resources Information Center

    Mayer, Richard E.

    2010-01-01

    Among his many accomplishments in educational psychology, Merlin C. Wittrock is perhaps best remembered for his enduring contributions to the science of learning. His vision of how learning works is best explicated in articles published in "Educational Psychologist" (Wittrock, 1974, 1978, 1989, 1991, 1992), beginning with his classic 1974 article,…

  5. Nutritional strategies to modulate the adaptive response to endurance training.

    PubMed

    Hawley, John A

    2013-01-01

    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.

  6. Molecular responses to moderate endurance exercise in skeletal muscle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  7. Strength and Endurance Training Prescription in Healthy and Frail Elderly

    PubMed Central

    Cadore, Eduardo Lusa; Pinto, Ronei Silveira; Bottaro, Martim; Izquierdo, Mikel

    2014-01-01

    Aging is associated with declines in the neuromuscular and cardiovascular systems, resulting in an impaired capacity to perform daily activities. Frailty is an age-associated biological syndrome characterized by decreases in the biological functional reserve and resistance to stressors due to changes in several physiological systems, which puts older individuals at special risk of disability. To counteract the neuromuscular and cardiovascular declines associated with aging, as well as to prevent and treat the frailty syndrome, the strength and endurance training seems to be an effective strategy to improve muscle hypertrophy, strength and power output, as well as endurance performance. The first purpose of this review was discuss the neuromuscular adaptations to strength training, as well as the cardiovascular adaptations to endurance training in healthy and frail elderly subjects. In addition, the second purpose of this study was investigate the concurrent training adaptations in the elderly. Based on the results found, the combination of strength and endurance training (i.e., concurrent training) performed at moderate volume and moderate to high intensity in elderly populations is the most effective way to improve both neuromuscular and cardiorespiratory functions. Moreover, exercise interventions that include muscle power training should be prescribed to frail elderly in order to improve the overall physical status of this population and prevent disability. PMID:24900941

  8. Solution-Space Screening of a Hypersonic Endurance Demonstrator

    NASA Technical Reports Server (NTRS)

    Chudoba, Bernd; Coleman, Gary; Oza, Amit; Gonzalez, Lex; Czysz, Paul

    2012-01-01

    This report documents a parametric sizing study performed to develop a program strategy for research and development and procurement of a feasible next-generation hypersonic air-breathing endurance demonstrator. Overall project focus has been on complementing technical and managerial decision-making during the earliest conceptual design phase towards minimization of operational, technical, and managerial risks.

  9. The Effect of Variant Dosages of Amphetamine Upon Endurance.

    ERIC Educational Resources Information Center

    Williams, Melvin H.; Thompson, John

    The purpose of this study was to provide basic information concerning the acute effects of a small, moderate, and large dose of d-amphetamine sulfate upon muscular endurance; a secondary purpose involved the effect upon resting (R), and submaximal, and maximal (MAX) heart rate (HR). Twelve male university students underwent four separate trials of…

  10. Cardiovascular Endurance Activities for Children in Grades Four Through Six.

    ERIC Educational Resources Information Center

    Thompson, Mary Ann

    A program of cardiovascular endurance activities for children in grades four through six was developed to emphasize success and improvement and establish lifelong patterns of concern for and enjoyment of activities that contribute to physical fitness and optimum health. The activities in the program require more teacher preparation than the…

  11. Nutrient Intake and Dietary Habits of Women Endurance Athletes.

    ERIC Educational Resources Information Center

    Wiseman, Juliet

    Dietary information was collected from a sample of women endurance athletes (n=16). Seven-day food intake records were taken using a semiweighted method. Questionnaires were used to obtain additional information on training, supplements, and attitudes toward diet. Notable features of the diets were a low average energy intake while mean intakes of…

  12. Ischemic Preconditioning Enhances Muscle Endurance during Sustained Isometric Exercise.

    PubMed

    Tanaka, D; Suga, T; Tanaka, T; Kido, K; Honjo, T; Fujita, S; Hamaoka, T; Isaka, T

    2016-07-01

    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.

  13. RESISTIVE EXERCISES IN THE DEVELOPMENT OF MUSCULAR STRENGTH AND ENDURANCE.

    ERIC Educational Resources Information Center

    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…

  14. An example of endurance in an old wolf, Canis lupus

    USGS Publications Warehouse

    Mech, L.D.

    1997-01-01

    An 11 to 13-year-old Arctic Wolf (Canis lupus arctos) was observed chasing a young Arctic Hare (Lepus arcticus) for 6 to 7 minutes and catching it. This provides an example of the degree of endurance of which an old wolf is capable.

  15. Chronic and acute effects of endurance training on telomere length.

    PubMed

    Borghini, Andrea; Giardini, Guido; Tonacci, Alessandro; Mastorci, Francesca; Mercuri, Antonella; Mrakic-Sposta, Simona; Sposta, Simona Mrakic; Moretti, Sarah; Andreassi, Maria Grazia; Pratali, Lorenza

    2015-09-01

    Telomere shortening is considered a cellular marker of health status and biological ageing. Exercise may influence the health and lifespan of an individual by affecting telomere length (TL). However, it is unclear whether different endurance exercise levels may have beneficial or detrimental effects on biological aging. The aims of the study were to assess both chronic and acute effects of endurance training on TL after an exceptional and extreme trail race. TL was assessed in 20 endurance athletes (17 males; age = 45.4 ± 9.2 years) and 42 age- and gender-matched sedentary controls (32 males; age = 45.9 ± 9.5 years) with quantitative real-time PCR at baseline conditions. Of the 20 runners enrolled in the 'Tor des Géants ®' ultra-distance trail race, 15 athletes (12 males; age = 47.2 ± 8.5 years) were re-evaluated at the intermediate point and 14 athletes (11 males; age = 47.1 ± 8.8 years) completed the competition and were analysed at the final point. Comparison between the two groups (endurance athletes vs. sedentary controls) revealed a significant difference in TL (1.28 ± 0.4 vs. 1.02 ± 0.3, P = 0.005). TL was better preserved in elder endurance runners compared with the same age control group (1.3 ± 0.27 vs. 0.91 ± 0.21, P = 0.003). TL was significantly reduced at the intermediate (0.88 ± 0.36 vs. 1.11 ± 0.34, P = 0.002) and final point compared with baseline measurements (0.86 ± 0.4 vs. 1.11 ± 0.34, P = 0.0006) for athletes engaged in the ultra-marathon race. Our data suggest that chronic endurance training may provide protective effects on TL attenuating biological aging. Conversely, acute exposure to an ultra-distance endurance trail race implies telomere shortening probably caused by oxidative DNA damage.

  16. Forced Running Endurance Is Influenced by Gene(s) on Mouse Chromosome 10

    PubMed Central

    Kvedaras, Mindaugas; Minderis, Petras; Fokin, Andrej; Ratkevicius, Aivaras; Venckunas, Tomas; Lionikas, Arimantas

    2017-01-01

    Phenotypic diversity between laboratory mouse strains provides a model for studying the underlying genetic mechanisms. The A/J strain performs poorly in various endurance exercise models. The aim of the study was to test if endurance capacity and contractility of the fast- and slow-twitch muscles are affected by the genes on mouse chromosome 10. The C57BL/6J (B6) strain and C57BL/6J-Chr 10A/J/NaJ (B6.A10) consomic strain which carries the A/J chromosome 10 on a B6 strain background were compared. The B6.A10 mice compared to B6 were larger in body weight (p < 0.02): 27.2 ± 1.9 vs. 23.8 ± 2.7 and 23.4 ± 1.9 vs. 22.9 ± 2.3 g, for males and females, respectively, and in male soleus weight (p < 0.02): 9.7 ± 0.4 vs. 8.6 ± 0.9 mg. In the forced running test the B6.A10 mice completed only 64% of the B6 covered distance (p < 0.0001). However, there was no difference in voluntary wheel running (p = 0.6) or in fatigability of isolated soleus (p = 0.24) or extensor digitorum longus (EDL, p = 0.7) muscles. We conclude that chromosome 10 of the A/J strain contributes to reduced endurance performance. We also discuss physiological mechanisms and methodological aspects relevant to interpretation of these findings. PMID:28167917

  17. Effect of Microstructure on Torsional Fatigue Endurance of Martensitic Carbon Steel

    NASA Astrophysics Data System (ADS)

    Toyoda, Shunsuke; Ishiguro, Yasuhide; Kawabata, Yoshikazu; Sakata, Kei; Sato, Akio; Sakai, Jun'ichi

    The microstructural influence of martensitic carbon steel on torsional fatigue endurance was investigated, taking into consideration the application of high strength steel electric resistance welded (ERW) tubes to automotive structural parts. The chemical composition of the base steel alloy was 0.1-0.2%C-0.2-1.5%Si-1.3-1.9%Mn-0.01%P-0.001%S-(Cr, Mo, Ti, Nb, B). Laboratory vacuum-fused ingots were hot-rolled, heated to 1023 or 1223 K in a salt bath, and then water-quenched and tempered at 473 K. Consequently, three types of microstructure, martensite (M), martensite and ferrite (M+F), and ferrite and pearlite (F+P), were prepared. Fully reversed torsional fatigue testing was conducted with 6 mm diameter round bar specimens. Torsional fatigue endurance was found to monotonously increase with increases in the tensile strength of the specimen from 540 to 1380 MPa. The martensitic single structure and the M+F dual-phase structure showed a similar level of fatigue endurance at a tensile strength of approximately 950 MPa. However, fatigue micro-crack morphology varied slightly between them. At the surface of the M+F specimen, many small cracks were observed in addition to the main crack. Conversely, in the martensitic specimen, these small cracks were rarely observed. ΔK decreasing/increasing crack growth testing with compact tension (CT)-type specimens was also conducted. Based on these experimental results, the effect of microstructure and stress level on the initiation/propagation cycle ratio is discussed. In addition to fatigue properties, some practical properties, such as low-temperature toughness and hydrogen embrittlement resistance, were also evaluated in view of actual applications for automotive structural parts.

  18. Risk factors for stress fracture in female endurance athletes: a cross-sectional study

    PubMed Central

    Duckham, Rachel L; Peirce, Nicholas; Meyer, Caroline; Summers, Gregory D; Cameron, Noël; Brooke-Wavell, Katherine

    2012-01-01

    Objective To identify psychological and physiological correlates of stress fracture in female endurance athletes. Design A cross-sectional design was used with a history of stress fractures and potential risk factors assessed at one visit. Methods Female-endurance athletes (58 runners and 12 triathletes) aged 26.0±7.4 years completed questionnaires on stress fracture history, menstrual history, athletic training, eating psychopathology and exercise cognitions. Bone mineral density, body fat content and lower leg lean tissue mass (LLLTM) were assessed using dual-x-ray absorptiometry. Variables were compared between athletes with a history of stress fracture (SF) and those without (controls; C) using χ², analysis of variance and Mann-Whitney U tests. Results Nineteen (27%) athletes had previously been clinically diagnosed with SFs. The prevalence of current a/oligomenorrhoea and past amenorrhoea was higher in SF than C (p=0.008 and p=0.035, respectively). SF recorded higher global scores on the eating disorder examination questionnaire (p=0.049) and compulsive exercise test (p=0.006) and had higher LLLTM (p=0.029) compared to C. These findings persisted with weight and height as covariates. In multivariate logistic regression, compulsive exercise, amenorrhoea and LLLTM were significant independent predictors of SF history (p=0.006, 0.009 and 0.035, respectively). Conclusions Eating psychopathology was associated with increased risk of SF in endurance athletes, but this may be mediated by menstrual dysfunction and compulsive exercise. Compulsive exercise, as well as amenorrhoea, is independently related to SF risk. PMID:23166136

  19. EFFECTS OF SELF-SELECTED MUSIC ON MAXIMAL BENCH PRESS STRENGTH AND STRENGTH ENDURANCE.

    PubMed

    Bartolomei, Sandro; Di Michele, Rocco; Merni, Franco

    2015-06-01

    Listening to music during strength workouts has become a very common practice. The goal of this study was to assess the effect of listening to self-selected music on strength performances. Thirty-one resistance-trained men (M age = 24.7 yr., SD = 5.9; M height = 178.7 cm, SD = 4.7; M body mass = 83.54 kg, SD = 12.0) were randomly assigned to either a Music group (n = 19) or to a Control group (n = 12). Both groups took part in two separate sessions; each session consisted in a maximal strength test (1-RM) and a strength-endurance test (repetitions to failure at 60% 1-RM) using the bench press exercise. The music group listened to music in the second assessment session, while the control group performed both tests without music. Listening to music induced a significant increase of strength endurance performance and no effects on maximal strength. These findings have implications for the use of music during strength workouts.

  20. A detailed study on the thermal endurance of Kapton HNTM and Upilex STM

    NASA Astrophysics Data System (ADS)

    Heltzel, S.; Semprimoschnig, C. O. A.

    2003-09-01

    Assessing the thermal endurance by isothermal testing in a Thermogravimetric Analyser (TGA) is a time consuming method. A quicker method is to perform kinetic modelling on several decomposition curves. Four temperature scans at different heating rates were recorded with the TGA for two thermal control foils, Kapton HN and Upilex S. Two methods of kinetic modelling were used to calculate the activation energy, i.e. the ASTM E 1641 and the approach of Model Free Kinetics (MFK). The first assumes a constant value for the activation energy whereas the latter calculates it as a function of the conversion. With the activation energy it is possible to make a lifetime prediction that indicates the mass loss that occurs at a certain temperature for a certain duration. The lifetime predictions are used to compare the two materials and also the two modelling methods. The modelling is verified by comparing the results to isothermal TGA tests and thermal ageing of samples in high vacuum chambers at 350°C for durations up to half a year and in combination with UV irradiation screening tests. All the performed experiments indicate that Upilex S has a better thermal endurance than Kapton HN. The results of the kinetic modelling are in good agreement with the isothermal experiments in the TGA and in the vacuum facilities. The MFK approach for kinetic modelling was found to be more adequate than the ASTM method.

  1. EFFECTS OF LISTENING TO PREFERENTIAL MUSIC ON SEX DIFFERENCES IN ENDURANCE RUNNING PERFORMANCE.

    PubMed

    Cole, Zachary; Maeda, Hotaka

    2015-10-01

    Music is a common accompaniment to exercise, but some running environments do not allow for personalized control over the music stimulus. The purpose of this study was to explore the effects of listening to preferred versus non-preferred music on sex differences in running performance. The sample consisted of 20 women and 15 men (M = 20.7 yr., SD = 2.3) who reported running at least once per week over the previous year. The participants completed three 12-min. Cooper Tests (i.e., aerobic fitness test) accompanied by preferred, non-preferred, or no music in randomized order. A 2 × 2 repeated-measures analysis of covariance (ANCOVA) was used to test the effect of music preference and sex on endurance running performance while controlling for the distance run with no music. Women ran further in the preferred music condition. However, music selection did not significantly change running performance for men. Listening to preferred instead of non-preferred music had a larger effect on the endurance running performance of women than men.

  2. Dietary milk fat globule membrane improves endurance capacity in mice.

    PubMed

    Haramizu, Satoshi; Ota, Noriyasu; Otsuka, Atsuko; Hashizume, Kohjiro; Sugita, Satoshi; Hase, Tadashi; Murase, Takatoshi; Shimotoyodome, Akira

    2014-10-15

    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.

  3. Endurance training in patients with schizophrenia and healthy controls: differences and similarities.

    PubMed

    Keller-Varady, Katriona; Hasan, Alkomiet; Schneider-Axmann, Thomas; Hillmer-Vogel, Ursula; Adomßent, Björn; Wobrock, Thomas; Schmitt, Andrea; Niklas, Andree; Falkai, Peter; Malchow, Berend

    2016-08-01

    The aims were to examine the feasibility of and adaptations to endurance training in persons diagnosed with schizophrenia and to address the question whether the principles and beneficial effects of endurance training established in the healthy population apply also to patients with schizophrenia. In this controlled interventional study, 22 patients with schizophrenia and 22 healthy controls performed a standardized aerobic endurance training on bicycle ergometers over 12 weeks. Another group of 21 patients with schizophrenia played table soccer. Endurance capacity was measured with incremental cycle ergometry before and after the intervention and 3 months later. A specific set of outcome parameters was defined. The training stimuli can be assumed to be similar in both endurance groups. Endurance capacity improved significantly in the endurance groups, but not in the table soccer group. Patients and healthy controls showed comparable adaptations to endurance training, as assessed by physical working capacity and maximal achieved power. Differences were found in changes of performance at a lactate concentration of 3 mmol/l. Endurance training was feasible and effective in both groups. The principles and types of training that are usually applied to healthy controls need to be verified in patients with schizophrenia. Nevertheless, patients benefited from endurance training in terms of improvement of endurance capacity and reduction in the baseline deficit in comparison with healthy controls. Therefore, endurance training should be implemented in future therapy programs. These programs need to pay special attention to the differences between patients with schizophrenia and healthy controls.

  4. Age-Related Differences in Muscular Strength and Muscular Endurance among Female Masters Swimmers.

    ERIC Educational Resources Information Center

    Dummer, Gail M.; And Others

    1985-01-01

    This study investigated age-related differences in muscular strength and muscular endurance among 73 female masters swimmers aged 24 to 71 years. While an age-related decline in muscular strength was apparent, the results failed to reveal a similar trend for endurance, suggesting that swimming influences endurance more than strength among women.…

  5. Acute neuromuscular and metabolic responses to combined strength and endurance loadings: the "order effect" in recreationally endurance trained runners.

    PubMed

    Taipale, Ritva S; Schumann, Moritz; Mikkola, Jussi; Nyman, Kai; Kyröläinen, Heikki; Nummela, Ari; Häkkinen, Keijo

    2014-01-01

    The study examined the acute neuromuscular and metabolic responses and recovery (24 and 48 h) to combined strength and endurance sessions (SEs). Recreationally endurance trained men (n = 12) and women (n = 10) performed: endurance running followed immediately by a strength loading (combined endurance and strength session (ES)) and the reverse order (SE). Maximal strength (MVC), countermovement jump height (CMJ), and creatine kinase activity were measured pre-, mid-, post-loading and at 24 and 48 h of recovery. MVC and CMJ were decreased (P < 0.05) at post-ES and SE sessions in men. Only MVC decreased in ES and SE women (P < 0.05). During recovery, no order differences in MVC were observed between sessions in men, but MVC and CMJ remained decreased. During recovery in women, a delayed decrease in CMJ was observed in ES but not in SE (P < 0.01), while MVC returned to baseline at 24 h. Creatine kinase increased (P < 0.05) during both ES and SE and peaked in all groups at 24 h. The present combined ES and SE sessions induced greater neuromuscular fatigue at post in men than in women. The delayed fatigue response in ES women may be an order effect related to muscle damage.

  6. Associations between Trunk Extension Endurance and Isolated Lumbar Extension Strength in Both Asymptomatic Participants and Those with Chronic Low Back Pain

    PubMed Central

    Conway, Rebecca; Behennah, Jessica; Fisher, James; Osborne, Neil; Steele, James

    2016-01-01

    Background: Strength and endurance tests are important for both clinical practice and research due to the key role they play in musculoskeletal function. In particular, deconditioning of the lumbar extensor musculature has been associated with low back pain (LBP). Due to the relationship between strength and absolute endurance, it is possible that trunk extension (TEX) endurance tests could provide a proxy measure of isolated lumbar extension (ILEX) strength and thus represent a simple, practical alternative to ILEX measurements. Though, the comparability of TEX endurance and ILEX strength is presently unclear and so the aim of the present study was to examine this relationship. Methods: Thirty eight healthy participants and nineteen participants with non-specific chronic LBP and no previous lumbar surgery participated in this cross-sectional study design. TEX endurance was measured using the Biering–Sorensen test. A maximal ILEX strength test was performed on the MedX lumbar-extension machine. Results: A Pearson’s correlation revealed no relationship between TEX endurance and ILEX strength in the combined group (r = 0.035, p = 0.793), the chronic LBP group (r = 0.120, p = 0.623) or the asymptomatic group (r = −0.060, p = 0.720). Conclusions: The results suggest that TEX is not a good indicator of ILEX and cannot be used to infer results regarding ILEX strength. However, a combination of TEX and ILEX interpreted together likely offers the greatest and most comprehensive information regarding lumbo-pelvic function during extension. PMID:27657149

  7. Strength, Endurance, Throwing Velocity and in-Water Jump Performance of Elite German Water Polo Players

    PubMed Central

    Zinner, Christoph; Sperlich, Billy; Krueger, Malte; Focke, Tim; Reed, Jennifer; Mester, Joachim

    2015-01-01

    The purpose of this study was threefold: 1) to assess the eggbeater kick and throwing performance using a number of water polo specific tests, 2) to explore the relation between the eggbeater kick and throwing performance, and 3) to investigate the relation between the eggbeater kick in the water and strength tests performed in a controlled laboratory setting in elite water polo players. Fifteen male water polo players of the German National Team completed dynamic and isometric strength tests for muscle groups (adductor, abductor, abdominal, pectoralis) frequently used during water polo. After these laboratory strength tests, six water polo specific in-water tests were conducted. The eggbeater kick assessed leg endurance and agility, maximal throwing velocity and jump height. A 400 m test and a sprint test examined aerobic and anaerobic performance. The strongest correlation was found between jump height and arm length (p < 0.001, r = 0.89). The laboratory diagnostics of important muscles showed positive correlations with the results of the in-water tests (p < 0.05, r = 0.52–0.70). Muscular strength of the adductor, abdominal and pectoralis muscles was positively related to in-water endurance agility as assessed by the eggbeater kick (p < 0.05; r = 0.53–0.66). Findings from the current study emphasize the need to assess indices of water polo performance both in and out of the water as well as the relation among these parameters to best assess the complex profile of water polo players. PMID:25964818

  8. Kinesio Taping and the Circulation and Endurance Ratio of the Gastrocnemius Muscle

    PubMed Central

    Stedge, Hannah L.; Kroskie, Ryan M.; Docherty, Carrie L.

    2012-01-01

    Context Kinesio Tex tape is a therapeutic tape that is applied with the Kinesio-taping (KT) method and is theorized to increase circulation and subsequently improve muscle function. However, little research has been conducted to determine how KT affects performance. Objective To determine the effect of KT on muscular endurance ratio, blood flow, circumference, and volume of the gastrocnemius muscle. Design Randomized controlled clinical trial. Setting Research laboratory. Patients or Other Participants Sixty-one healthy, active people (23 men, 38 women; age = 19.99 ± 8.01 years, height = 169.42 ± 23.62 cm, mass = 71.53 ± 36.77 kg) volunteered to participate. They were assigned randomly to 1 of 3 groups: treatment KT, sham KT, and control. Intervention(s) Tape was applied based on group assignment. The treatment KT group received the ankle-tape technique as described in the KT manual. The sham KT group received 1 strip of Kinesio Tex tape around the circumference of the proximal gastrocnemius muscle. The control group did not receive tape application. Main Outcome Measure(s) The dependent variables were blood flow in blood perfusion units, volume of water displacement in milliliters, circumference of the gastrocnemius muscle in centimeters, and endurance ratio in joules measured before, 24 hours after, and 72 hours after the intervention. Separate repeated-measures analyses of variance were conducted for each dependent variable. Results We found no group-by-test day interaction for endurance ratios (F4,116 = 1.99, P = .10). Blood flow, circumference, and volume measurements also yielded no differences among groups (F2,58 range, 0.02–0.51; P > .05) or test days (F2,116 range, 0.05–2.33; P > .05). Conclusions We found KT does not enhance anaerobic muscle function measured by endurance ratio. The KT also did not affect circulation or volume of the gastrocnemius muscle in a healthy population. PMID:23182011

  9. The Ellsworth Mountains: critical and enduringly enigmatic

    USGS Publications Warehouse

    Dalziel, I.W.D.

    2007-01-01

    The elevation (~5000m) is high for an early Mesozoic fold belt. Thermal uplift could have been initiated during Jurassic-Cretaceous block rotation and Weddell Sea opening and continued into the Cenozoic. The history of glaciation provides input for models of ice loading and unloading. Measurements of present-day uplift test these models and help assess change in the mass of the ice sheet and hence in global sea level.

  10. Acute phase protein concentrations after limited distance and long distance endurance rides in horses.

    PubMed

    Cywińska, Anna; Szarska, Ewa; Górecka, Renata; Witkowski, Lucjan; Hecold, Mateusz; Bereznowski, Andrzej; Schollenberger, Antoni; Winnicka, Anna

    2012-12-01

    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.

  11. Tolerance of Lower Body Negative Pressure (LBNP) in endurance runners, weightlifters, swimmers and nonathletes

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Thirteen endurance runners (R), 12 weightlifters (WL), 12 swimmers (SW) and 10 nonathletes (NA) were tested for their tolerance of lower body negative pressure (LBNP) in consecutive 5 minute stages at -20, -30, -40, -50 and -60 torr. Each subject also performed an exercise test on a bicycle ergometer with progressive workloads to exhaustion to determined aerobic capacity. The R had a much higher aerobic capacity than any of the other groups, but a significantly lower LBNP tolerance. While responses in heart rate and pulse pressure were quite similar in all 4 groups, the rate of increase in leg volume relative to LBNP stress (leg compliance, LC) was considerably greater in R than in the other athletes and NA. The greater LC in R could be attributed not only to a more rapid shift of blood to the lower extremities but also to a greater tendency for edema formation, both contributing to a more rapid loss in effective central blood volume for a given LBNP stress. These results substantiate earlier observations which led to the conclusion that endurance running is not advisable as a training regimen for astronauts.

  12. One- and two-dimensional echocardiography in body builders and endurance-trained subjects.

    PubMed

    Urhausen, A; Kindermann, W

    1989-04-01

    The object of the study was to investigate possible myocardial adaptations to intensive body building training and to differentiate them from the athlete's heart resulting from high intensive endurance training. Seven top-level body builders (BB) were examined by one- and two-dimensional echocardiography and bicycle ergometer step test. They were compared with seven highly endurance-trained athletes (E) using the matched pair procedure. BB showed normal blood pressure at rest and during ergometric exercise; their ergometric performance was in the normal range of sedentary subjects. Absolute left ventricular muscle mass (LVMM) as well as one-dimensional measurements of wall thickness and internal diameters were found to be similar in BB and E, while body weight and surface-related values were clearly higher in E. The ratios between LV myocardial thickness and internal diameter (M-mode) as well as between LVMM and LV volume (combined one- and two-dimensional method) were not statistically different between BB (0.356 +/- 0.077 and 1.10 +/- 0.16) and E (0.436 +/- 0.062 and 1.26 +/- 0.21). LV contractility was similar in both groups. Diastolic parameters showed only a slight tendency toward slower isovolumetric relaxation in BB. A significant correlation existed between lean body mass and LVMM in BB but not in E. The findings suggest that intense body building over a period of several years does not induce any form of concentric hypertrophy. Analogously to the increase in body dimensions, body building also causes an increase in heart size with an unchanged mass/volume ratio. There is no evidence of an enlargement of the heart in relation to body weight, as occurs in endurance athletes.

  13. Single and Concurrent Effects of Endurance and Resistance Training on Pulmonary Function

    PubMed Central

    Khosravi, Maryam; Tayebi, Seyed Morteza; Safari, Hamed

    2013-01-01

    Objective(s): As not only few evidences but also contradictory results exist with regard to the effects of resistance training (RT) and resistance plus endurance training (ERT) on respiratory system, so the purpose of this research was therefore to study single and concurrent effects of endurance and resistance training on pulmonary function. Materials and Methods: Thirty seven volunteer healthy inactive women were randomly divided into 4 groups: without training as control (C), Endurance Training (ET), RT, and ERT. A spirometry test was taken 24 hrs before and after the training course. The training period (8 weeks, 3 sessions/week) for ET was 20-26 min/session running with 60-80% maximum heart rate (HR max); for RT two circuits/session, 40-60s for each exercise with 60-80% one repetition maximum (1RM), and 1 and 3 minutes active rest between exercises and circuits respectively; and for ERT was in agreement with either ET or RT protocols, but the times of running and circuits were half of ET and RT. Results: ANCOVA showed that ET and ERT increased significantly (P< 0.05) vital capacity (VC), forced vital capacity (FVC), and forced expiratory flows to 25%-75%; ET, RT and ERT increased significantly (P< 0.05) maximum voluntary ventilation (MVV); and only ET increased significantly (P<0.05) peak expiratory flows (PEF); but ET, RT and ERT had no significant effect (P>0.05) on forced expiratory volume in one second (FEV1) and FEV1/FVC ratio. Conclusion: In conclusion, ET combined with RT (ERT) has greater effect on VC, FVC, FEF rating at25%-75%, and also on PEF except MVV, rather than RT, and just ET has greater effect rather than ERT. PMID:24250940

  14. Twins Bed Rest Project: LBNP/Exercise Minimizes Changes in Lean Leg Mass, Strength and Endurance

    NASA Technical Reports Server (NTRS)

    Amorim, Fabiano T.; Schneider, Suzanne M.; Lee, Stuart M. C.; Boda, Wanda L.; Watenpaugh, Donald E.; Hargens, Alan R.

    2006-01-01

    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.

  15. Faster heart rate and muscular oxygen uptake kinetics in type 2 diabetes patients following endurance training.

    PubMed

    Koschate, Jessica; Drescher, Uwe; Brinkmann, Christian; Baum, Klaus; Schiffer, Thorsten; Latsch, Joachim; Brixius, Klara; Hoffmann, Uwe

    2016-11-01

    Cardiorespiratory kinetics were analyzed in type 2 diabetes patients before and after a 12-week endurance exercise-training intervention. It was hypothesized that muscular oxygen uptake and heart rate (HR) kinetics would be faster after the training intervention and that this would be detectable using a standardized work rate protocol with pseudo-random binary sequences. The cardiorespiratory kinetics of 13 male sedentary, middle-aged, overweight type 2 diabetes patients (age, 60 ± 8 years; body mass index, 33 ± 4 kg·m(-2)) were tested before and after the 12-week exercise intervention. Subjects performed endurance training 3 times a week on nonconsecutive days. Pseudo-random binary sequences exercise protocols in combination with time series analysis were used to estimate kinetics. Greater maxima in cross-correlation functions (CCFmax) represent faster kinetics of the respective parameter. CCFmax of muscular oxygen uptake (pre-training: 0.31 ± 0.03; post-training: 0.37 ± 0.1, P = 0.024) and CCFmax of HR (pre-training: 0.25 ± 0.04; post-training: 0.29 ± 0.06, P = 0.007) as well as peak oxygen uptake (pre-training: 24.4 ± 4.7 mL·kg(-1)·min(-1); post-training: 29.3 ± 6.5 mL·kg(-1)·min(-1), P = 0.004) increased significantly over the course of the exercise intervention. In conclusion, kinetic responses to changing work rates in the moderate-intensity range are similar to metabolic demands occurring in everyday habitual activities. Moderate endurance training accelerated the kinetic responses of HR and muscular oxygen uptake. Furthermore, the applicability of the used method to detect these accelerations was demonstrated.

  16. Effects of vascular occlusion on muscular endurance in dynamic knee extension exercise at different submaximal loads.

    PubMed

    Wernbom, Mathias; Augustsson, Jesper; Thomeé, Roland

    2006-05-01

    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.

  17. Paired changes in electromechanical delay and musculo-tendinous stiffness after endurance or plyometric training.

    PubMed

    Grosset, Jean-Francois; Piscione, Julien; Lambertz, Daniel; Pérot, Chantal

    2009-01-01

    When measured in vivo electromechanical delay (EMD) depends mainly on the elastic properties of the muscle-tendon unit. Recent studies have shown changes in stiffness of the triceps surae (TS) following a period of training. To confirm the influence of musculo-tendinous stiffness on EMD, this study investigates paired changes in these two parameters after a training period. Two types of training known to induce opposite changes in stiffness were analysed. EMD and musculo-tendinous stiffness were measured on adult subjects before and after 10 weeks of endurance (n = 21) or plyometric (n = 9) trainings. EMD was defined as the time lag between the TS M-wave latency and the onset of muscle twitch evoked at rest by supramaximal electrical stimulations of the posterior tibial nerve. Quick release tests were used to evaluate the musculo-tendinous stiffness of the ankle plantar flexors. The stiffness index was defined as the slope of the relationship between angular stiffness and external torque values. Endurance training, known to preferentially activate the slow, stiffer muscle fibers, leads to a decrease in EMD and to an increase in stiffness index. Following plyometric training, which specifically recruits fast, more compliant fibers, EMD and the stiffness index exhibited adaptations directionally opposite to those seen with endurance training. When pooling the data for the two subject groups, a correlation was found between changes in EMD and changes in musculo-tendinous stiffness indexes. Thus, changes in EMD values are proposed to indirectly link to changes in musculo-tendinous stiffness for subjects involved in muscle training.

  18. Effect of Red Bull energy drink on repeated Wingate cycle performance and bench-press muscle endurance.

    PubMed

    Forbes, Scott C; Candow, Darren G; Little, Jonathan P; Magnus, Charlene; Chilibeck, Philip D

    2007-10-01

    The purpose of this study was to determine the effects of Red Bull energy drink on Wingate cycle performance and muscle endurance. Healthy young adults (N = 15, 11 men, 4 women, 21 +/- 5 y old) participated in a crossover study in which they were randomized to supplement with Red Bull (2 mg/kg body mass of caffeine) or isoenergetic, isovolumetric, noncaffeinated placebo, separated by 7 d. Muscle endurance (bench press) was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% of baseline 1-repetition maximum. Three 30-s Wingate cycling tests (load = 0.075 kp/kg body mass), with 2 min recovery between tests, were used to assess peak and average power output. Red Bull energy drink significantly increased total bench-press repetitions over 3 sets (Red Bull = 34 +/- 9 vs. placebo = 32 +/- 8, P %%%lt; 0.05) but had no effect on Wingate peak or average power (Red Bull = 701 +/- 124 W vs. placebo = 700 +/- 132 W, Red Bull = 479 +/- 74 W vs. placebo = 471 +/- 74 W, respectively). Red Bull energy drink significantly increased upper body muscle endurance but had no effect on anaerobic peak or average power during repeated Wingate cycling tests in young healthy adults.

  19. Diesel Engine Idling Test

    SciTech Connect

    Larry Zirker; James Francfort; Jordon Fielding

    2006-02-01

    In support of the Department of Energy’s FreedomCAR and Vehicle Technology Program Office goal to minimize diesel engine idling and reduce the consumption of millions of gallons of diesel fuel consumed during heavy vehicle idling periods, the Idaho National Laboratory (INL) conducted tests to characterize diesel engine wear rates caused by extended periods of idling. INL idled two fleet buses equipped with Detroit Diesel Series 50 engines, each for 1,000 hours. Engine wear metals were characterized from weekly oil analysis samples and destructive filter analyses. Full-flow and the bypass filter cartridges were removed at four stages of the testing and sent to an oil analysis laboratory for destructive analysis to ascertain the metals captured in the filters and to establish wear rate trends. Weekly samples were sent to two independent oil analysis laboratories. Concurrent with the filter analysis, a comprehensive array of other laboratory tests ascertained the condition of the oil, wear particle types, and ferrous particles. Extensive ferrogram testing physically showed the concentration of iron particles and associated debris in the oil. The tests results did not show the dramatic results anticipated but did show wear trends. New West Technologies, LLC, a DOE support company, supplied technical support and data analysis throughout the idle test.

  20. Anthropometric, strength, endurance and flexibility characteristics of elite and recreational climbers.

    PubMed

    Grant, S; Hynes, V; Whittaker, A; Aitchison, T

    1996-08-01

    There has been remarkable development in the scope and quality of rock climbing in recent years. However, there are scant data on the anthropometry, strength, endurance and flexibility of rock climbers. The aim of this study was to compare these characteristics in three groups of subjects-elite rock climbers, recreational climbers and non-climbers. The 30 male subjects were aged 28.8 +/- 8.1 (mean +/- S.D.) years. Group 1 (n = 10) comprised elite rock climbers who had led a climb of a minimum standard of 'E1' (E1-E9 are the highest climbing grades) within the previous 12 months; Group 2 (n = 10) comprised rock climbers who had achieved a standard no better than leading a climb considered 'severe' (a low climbing grade category); and Group 3 (n = 10) comprised physically active individuals who had not previously done any rock climbing. The test battery included tests of finger strength [grip strength, pincer (i.e. thumb and forefinger) strength, finger strength measured on climbing-specific apparatus], body dimensions, body composition, flexibility, arm strength and endurance, and abdominal endurance. The tests which resulted in significant differences (P < 0.05) between the three groups included the bent arm hang (elite 53.1 +/- 1.32 s; recreational 31.4 +/- 9.0 s; non-climbers 32.6 +/- 15.0 s) and pull-ups (elite 16.2 +/- 7.2 repetitions; recreational 3.0 +/- 4.0 reps; non-climbers 3.0 +/- 3.9 reps); for both tests, the elite climbers performed significantly better than the recreational climbers and non-climbers. Regression procedures (i.e. analysis of covariance) were used to examine the influence of body mass and length. Using adjusted means (i.e. for body mass and leg length), significant differences were obtained for the following: (1) finger strength, grip 1, four fingers (right hand) (elite 447 +/- 30 N; recreational 359 +/- 29 N; non-climbers 309 +/- 30 N), (2) grip strength (left hand) (elite 526 +/- 21 N; recreational 445 +/- 21 N; non-climbers 440 +/- 21

  1. Climbing-specific finger endurance: a comparative study of intermediate rock climbers, rowers and aerobically trained individuals.

    PubMed

    Grant, S; Shields, C; Fitzpatrick, V; Loh, W Ming; Whitaker, A; Watt, I; Kay, J W

    2003-08-01

    The aim of this study was to compare the climbing-specific finger endurance of climbers, rowers and aerobically leg trained athletes. Twenty-seven males aged 21.2 +/- 2.2 years (mean +/- s) volunteered for the study. The participants were intermediate rock climbers (n = 9), rowers (n = 9) and leg trained athletes (n = 9). Maximal voluntary contraction (MVC) was determined on climbing-specific finger apparatus. Endurance isometric exercise was performed at 40% MVC in three tests performed in a random order: (1) sustained exercise; (2) 6 s exercise, 4 s rest; and (3) 18 s exercise, 12 s rest. Pre- and post-exercise blood pressure and blood lactate concentration, together with post-exercise pain perception, were measured. The climbers had a significantly greater MVC (383 +/- 35.6 N) than the rowers (321 +/- 49.5 N, P = 0.007) and aerobically leg trained athletes (288 +/- 60.6 N, P = 0.001). There were no significant differences between the groups in terms of endurance times for any of the tests. In the test with 18 s exercise and 12 s rest, the climbers showed a significantly higher increase in blood lactate concentration, on average, than the rowers by 0.01-0.89 mmol x l(-1) (P = 0.006); there were no significant differences, on average, in the comparisons of climbers and the leg trained athletes and rowers and the leg trained athletes. There were no significant differences in the average changes in blood pressure from rest to post-exercise between any of the groups. Although the climbers had greater MVC on average than the other two groups, there were no significant differences in average endurance times amongthe groups. These findings suggest that training for rock climbing and participation in rock climbing may result in some specific adaptations. However, we acknowledge that this study is descriptive and there is the possibility that differences between groups could be attributed to self-selection.

  2. Fatigue Induced by Physical and Mental Exertion Increases Perception of Effort and Impairs Subsequent Endurance Performance

    PubMed Central

    Pageaux, Benjamin; Lepers, Romuald

    2016-01-01

    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

  3. Willard and Spackman's Enduring Legacy for Future Occupational Therapy Pathways.

    PubMed

    Mahoney, Wanda J; Peters, Christine O; Martin, Peggy M

    Helen Willard (1894-1980) and Clare Spackman (1909-1992) paved the way for modern and future occupational therapy. This article validates the need for historical research in occupational therapy and presents a historical study on how the personal and professional collaboration of Willard and Spackman influenced occupational therapy. Data were gathered from archival documents, private papers, and 10 oral histories with colleagues, students, family, and friends. We used text analysis with triangulation to develop themes to reconstruct a proximity of the historical story. Two major themes that describe Willard's and Spackman's influence on occupational therapy are (1) Enduring Legacies and (2) Sacred Solitude and Chosen Gatherings. Subthemes within Enduring Legacies include Guiding Practice, Leaders in Service, and Educational Leadership. These women strongly influenced practitioners worldwide while maintaining the sacredness of their private lives. Their example can serve as a model for current and future occupational therapy practitioners and leaders.

  4. Hypertrophic cardiomyopathy and ultra-endurance running - two incompatible entities?

    PubMed Central

    2011-01-01

    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

  5. Differences in Resting State Functional Connectivity between Young Adult Endurance Athletes and Healthy Controls

    PubMed Central

    Raichlen, David A.; Bharadwaj, Pradyumna K.; Fitzhugh, Megan C.; Haws, Kari A.; Torre, Gabrielle-Ann; Trouard, Theodore P.; Alexander, Gene E.

    2016-01-01

    Expertise and training in fine motor skills has been associated with changes in brain structure, function, and connectivity. Fewer studies have explored the neural effects of athletic activities that do not seem to rely on precise fine motor control (e.g., distance running). Here, we compared resting-state functional connectivity in a sample of adult male collegiate distance runners (n = 11; age = 21.3 ± 2.5) and a group of healthy age-matched non-athlete male controls (n = 11; age = 20.6 ± 1.1), to test the hypothesis that expertise in sustained aerobic motor behaviors affects resting state functional connectivity in young adults. Although generally considered an automated repetitive task, locomotion, especially at an elite level, likely engages multiple cognitive actions including planning, inhibition, monitoring, attentional switching and multi-tasking, and motor control. Here, we examined connectivity in three resting-state networks that link such executive functions with motor control: the default mode network (DMN), the frontoparietal network (FPN), and the motor network (MN). We found two key patterns of significant between-group differences in connectivity that are consistent with the hypothesized cognitive demands of elite endurance running. First, enhanced connectivity between the FPN and brain regions often associated with aspects of working memory and other executive functions (frontal cortex), suggest endurance running may stress executive cognitive functions in ways that increase connectivity in associated networks. Second, we found significant anti-correlations between the DMN and regions associated with motor control (paracentral area), somatosensory functions (post-central region), and visual association abilities (occipital cortex). DMN deactivation with task-positive regions has been shown to be generally beneficial for cognitive performance, suggesting anti-correlated regions observed here are engaged during running. For all between

  6. Differences in Resting State Functional Connectivity between Young Adult Endurance Athletes and Healthy Controls.

    PubMed

    Raichlen, David A; Bharadwaj, Pradyumna K; Fitzhugh, Megan C; Haws, Kari A; Torre, Gabrielle-Ann; Trouard, Theodore P; Alexander, Gene E

    2016-01-01

    Expertise and training in fine motor skills has been associated with changes in brain structure, function, and connectivity. Fewer studies have explored the neural effects of athletic activities that do not seem to rely on precise fine motor control (e.g., distance running). Here, we compared resting-state functional connectivity in a sample of adult male collegiate distance runners (n = 11; age = 21.3 ± 2.5) and a group of healthy age-matched non-athlete male controls (n = 11; age = 20.6 ± 1.1), to test the hypothesis that expertise in sustained aerobic motor behaviors affects resting state functional connectivity in young adults. Although generally considered an automated repetitive task, locomotion, especially at an elite level, likely engages multiple cognitive actions including planning, inhibition, monitoring, attentional switching and multi-tasking, and motor control. Here, we examined connectivity in three resting-state networks that link such executive functions with motor control: the default mode network (DMN), the frontoparietal network (FPN), and the motor network (MN). We found two key patterns of significant between-group differences in connectivity that are consistent with the hypothesized cognitive demands of elite endurance running. First, enhanced connectivity between the FPN and brain regions often associated with aspects of working memory and other executive functions (frontal cortex), suggest endurance running may stress executive cognitive functions in ways that increase connectivity in associated networks. Second, we found significant anti-correlations between the DMN and regions associated with motor control (paracentral area), somatosensory functions (post-central region), and visual association abilities (occipital cortex). DMN deactivation with task-positive regions has been shown to be generally beneficial for cognitive performance, suggesting anti-correlated regions observed here are engaged during running. For all between

  7. Hannelore Wass: Death Education--An Enduring Legacy.

    PubMed

    Doka, Kenneth J

    2015-01-01

    Hannelore Wass's enduring contribution to the field of thanatology focused on death education In addition to developing a journal initially focused on that topic, Wass also created one of the first text books in the field. This article explores the factors that caused death education to emerge in the late 1960s as well as issues that death education still faces as it continues to evolve.

  8. Development of a Coping Strategies Questionnaire to Assess Endurance Performance,

    DTIC Science & Technology

    1987-10-16

    assessing the performance of two individuals trained similarly for a sustained operation (an operation lasting longer than six hours) or other...endurance related tasks, a question that often arises is "why is one individual able to complete the mission or task while his similarly trained partner is...primarily with psychological processes (e.g. used positive mental Imagery), (2) eight training or event strategies (e.g. tapered for this race), (3) tw

  9. Anaerobic Endurance of Young Untrained Male and Female Subjects

    ERIC Educational Resources Information Center

    Sienkiewicz-Dianzenza, Edyta; Tomaszewski, Pawel; Iwanska, Dagmara; Stupnicki, Romuald

    2009-01-01

    Study aim: To assess the anaerobic endurance of untrained male and female subjects by applying repeated maximal exercises. Material and methods: Untrained male subjects aged 23-27 years (n = 17, body height 170-197 cm, body mass 65-110 kg) and female ones aged 20-25 years (n = 10, body height 168-184 cm, body mass 55-86 kg) performed 6 maximal…

  10. Serum cardiac troponin T after repeated endurance exercise events.

    PubMed

    Bonetti, A; Tirelli, F; Albertini, R; Monica, C; Monica, M; Tredici, G

    1996-05-01

    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.

  11. Enduring symbols of dentistry: international metaphors of dental science.

    PubMed

    Pearn, J

    2008-12-13

    Dentists' contributions to science and society extend beyond the practice of clinical dentistry and preventive oral health. Such service encompasses contributions to biology specifically and more generally to societal good works for which dentists are particularly esteemed. The profession of dentistry promotes the history and heritage of its craft and those who practise it. Enduring symbols of dentistry take many forms. These include metonymic emblems such as those of Cadmus and Saint Apollonia and the portrayal of effigies of twentieth century dentists on eponymous medals. Other enduring symbols are to be found in the names of streets and towns (eg Normanville in Australia) which commemorate dentists; and in the worldwide scientific names of plants and animal species which perpetuate singular contributions of dentists to biological science. Such include the scientific names of grasses (Deyeuxia rodwayi) after the Tasmanian dentist, Dr Leonard Rodway (1853-1936); seaweeds (Jeannerettia sp.) after a seaweed of the Pacific and Southern Oceans, after Dr Henry Jeannerett (1802-1886); gastropods (Typhina yatesi) after Dr Lorenzo Yates (1837-1909); copepods (eg Mimocalanus heronae) named to commemorate the life and works of Gayle Ann Heron (b.1923), a dental hygienist of the University of Washington, USA; and crabs (eg Cancer bellianus) named to commemorate the life and works of the leading British dentist of his day, Thomas Bell (1792-1880). This paper explores this theme of the creation and promotion of enduring symbols of dental science - enshrined in the civic, numismatic and taxonomic record.

  12. Ultrasonic Fatigue Endurance of Aluminum Alloy AISI 6061-T6 on Pre-corroded and Non-corroded Specimens

    NASA Astrophysics Data System (ADS)

    Domínguez Almaraz, Gonzalo M.; Dueñas Aburto, Antonio; Correa Gómez, Erasmo

    2014-01-01

    Ultrasonic fatigue tests are carried out on aluminum alloy 6061-T6 in order to analyze the fatigue endurance behavior under artificial pre-corrosion attack by hydrochloric acid for the pH concentrations of 0.47 and 0.80. The pre-corrosion attack is used to simulate the long-time environmental effect and the corresponding decay of fatigue life in regard to non-corroded specimens. Experimental results show that ultrasonic fatigue endurance under these two degrees of pre-corrosion attack decreases dramatically. Furthermore, it is observed that crack initiation is frequently associated with one or several pre-corrosion pitting holes at the specimen surface. Pitting holes are assumed to be semi-hemispherical and the stress concentration factors are evaluated taking into account the size and proximity of two crack initiation pitting holes. The crack growth rates are obtained for the pre-corroded specimens and compared to the non-corroded specimen. Finally, conclusions are listed concerning ultrasonic fatigue endurance of testing specimens, together with the fracture surfaces, crack paths, and crack growth rates.

  13. Effect of unilateral, bilateral, and combined plyometric training on explosive and endurance performance of young soccer players.

    PubMed

    Ramírez-Campillo, Rodrigo; Burgos, Carlos H; Henríquez-Olguín, Carlos; Andrade, David C; Martínez, Cristian; Álvarez, Cristian; Castro-Sepúlveda, Mauricio; Marques, Mário C; Izquierdo, Mikel

    2015-05-01

    The aim of the study was to compare the effects of bilateral, unilateral, or combined bilateral and unilateral plyometric training (PT) on muscle power output, endurance, and balance performance adaptations in young soccer players. Four groups of young soccer players (age 11.4 ± 2.2 years) were divided into control group (CG; n = 14), bilateral group (BG; n = 12), unilateral group (UG; n = 16), and bilateral + unilateral group (B + UG; n = 12). Players were measured in unilateral and bilateral countermovement jump with arms, 5 multiple bounds test, 20-cm drop jump reactive strength index, maximal kicking velocity, sprint and agility test time, endurance, and balance performance. The PT was applied during 6 weeks, 2 sessions per week, for a total of 2,160 jumps. After intervention, all PT groups showed a statistically significant (p ≤ 0.05) change in all performance measures, with no statistically significant differences between treatments. Among the 21 performance measures, the B + UG showed a significantly (p ≤ 0.05) higher performance change in 13 of them vs. the CG, whereas the UG and BG showed only 6 and 3, respectively. The current study showed that bilateral, unilateral, and combined bilateral and unilateral PT ensured significant improvement in several muscular power and endurance performance measures in young soccer players. However, the combination of unilateral and bilateral drills seems more advantageous to induce superior performance improvements.

  14. Anaerobic energy provision does not limit Wingate exercise performance in endurance-trained cyclists.

    PubMed

    Calbet, J A L; De Paz, J A; Garatachea, N; Cabeza de Vaca, S; Chavarren, J

    2003-02-01

    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.

  15. Caffeine improves endurance in 75-yr-old citizens: a randomized, double-blind, placebo-controlled, crossover study.

    PubMed

    Norager, C B; Jensen, M B; Madsen, M R; Laurberg, S

    2005-12-01

    This study investigated the effect of caffeine on physical performance in healthy citizens aged > or =70 yr. The randomized, double-blind, placebo-controlled, crossover study was conducted in 15 men and 15 women recruited by their general practitioner. Participants abstained from caffeine for 48 h and were randomized to receive one capsule of placebo and then caffeine (6 mg/kg) or caffeine and then placebo with 1 wk in between. One hour after intervention, we measured reaction and movement times, postural stability, walking speed, cycling at 65% of expected maximal heart rate, perceived effort during cycling, maximal isometric arm flexion strength, and endurance. Analysis was by intention to treat, and P < 0.05 was regarded as significant. Caffeine increased cycling endurance by 25% [95% confidence interval (CI): 13-38; P = 0.0001] and isometric arm flexion endurance by 54% (95% CI: 29-83; P = 0.0001). Caffeine also reduced the rating of perceived exertion after 5 min of cycling by 11% (95% CI: 5-17; P = 0.002) and postural stability with eyes open by 25% (95% CI: 2-53; P = 0.03). Caffeine ingestion did not affect muscle strength, walking speed, reaction, and movement times. At the end of the study, 46% of participants correctly identified when they received caffeine and placebo. Caffeine increased exercise endurance in healthy citizens aged > or =70 yr, but the participants' reasons for stopping the test may have varied between subjects, as the cycling test was done at approximately 55% of maximal oxygen consumption. Further studies are required to investigate whether caffeine can be utilized to improve the physical performance of elderly citizens.

  16. ACTN3 R577X and other polymorphisms are not associated with elite endurance athlete status in the Genathlete study.

    PubMed

    Döring, Frank E; Onur, Simone; Geisen, Ulf; Boulay, Marcel R; Pérusse, Louis; Rankinen, Tuomo; Rauramaa, Rainer; Wolfahrt, Bernd; Bouchard, C

    2010-10-01

    Homozygosity for a premature stop codon at amino acid position 577 in the alpha-actinin-3 (ACTN3) gene leads to α-actinin-3 deficiency. This genotype is observed in approximately 18% of Caucasians. The ACTN3 R577X polymorphism has been previously associated with indicators of physical performance in several, but not all, studies. We examined the prevalence of R577X (rs1815739) and two additional haplotype tagging single nucleotide polymorphisms (htSNPs) of the ACTN3 gene (rs1791690 and rs2275998) in the Genathlete study comprising 316 male elite endurance athletes (VO2max 79.0+3.5 ml · kg(-1) · min(-1); mean +/- s) from North America, Finland, and Germany and 304 sedentary controls (VO2max 40.1+7.0 ml · kg(-1) · min(-1) matched by country of origin. The distribution of genotype and allele frequencies between the two groups was tested by Pearson chi-square and/or Fischer exact test. The prevalence of the 577X homozygote genotype was similar in endurance athletes and controls (20% and 17.5%, respectively). The resulting odds ratio for endurance performance in 577X homozygotes compared with 577R-allele carriers was 1.24 (95%CI 0.82-1.87, P = 0.3). The genotype distribution of the two htSNPs and haplotype frequencies did not differ significantly between athletes and controls. In conclusion, our findings indicate that ACTN3 R577X and other SNPs in ACTN3 are not genetic determinants of endurance performance in Caucasian males.

  17. Combined effects of endurance training and dietary unsaturated fatty acids on physical performance, fat oxidation and insulin sensitivity.

    PubMed

    Boss, Andreas; Lecoultre, Virgile; Ruffieux, Christiane; Tappy, Luc; Schneiter, Philippe

    2010-04-01

    Endurance training improves exercise performance and insulin sensitivity, and these effects may be in part mediated by an enhanced fat oxidation. Since n-3 and n-9 unsaturated fatty acids may also increase fat oxidation, we hypothesised that a diet enriched in these fatty acids may enhance the effects of endurance training on exercise performance, insulin sensitivity and fat oxidation. To assess this hypothesis, sixteen normal-weight sedentary male subjects were randomly assigned to an isoenergetic diet enriched with fish and olive oils (unsaturated fatty acid group (UFA): 52 % carbohydrates, 34 % fat (12 % SFA, 12 % MUFA, 5 % PUFA), 14 % protein), or a control diet (control group (CON): 62 % carbohydrates, 24 % fat (12 % SFA, 6 % MUFA, 2 % PUFA), 14 % protein) and underwent a 10 d gradual endurance training protocol. Exercise performance was evaluated by measuring VO2max and the time to exhaustion during a cycling exercise at 80 % VO2max; glucose homeostasis was assessed after ingestion of a test meal. Fat oxidation was assessed by indirect calorimetry at rest and during an exercise at 50 % VO2max. Training significantly increased time to exhaustion, but not VO2max, and lowered incremental insulin area under the curve after the test meal, indicating improved insulin sensitivity. Those effects were, however, of similar magnitude in UFA and CON. Fat oxidation tended to increase in UFA, but not in CON. This difference was, however, not significant. It is concluded that a diet enriched with fish- and olive oil does not substantially enhance the effects of a short-term endurance training protocol in healthy young subjects.

  18. Plasma treatment of fiber facets for increased (de)mating endurance in physical contact fiber connectors

    NASA Astrophysics Data System (ADS)

    Van Erps, Jürgen; Voss, Kevin; De Witte, Martijn; Radulescu, Radu; Beri, Stefano; Watté, Jan; Thienpont, Hugo

    2016-04-01

    It is known that cleaving an optical fiber introduces a number of irregularities and defects to the fiber's end-face, such as hackles and shockwaves. These defects can act as failure initiators when stress is applied to the end-face. Given the fiber's small diameter of 125 ffm, a large amount of mechanical stress can be expected to be applied on its end-face during the mating-demating cycle. In addition, a connector in a fiber-to-the-home (FTTH) network can be expected to be mated and demated more than 30 times during its lifetime for purposes such as testing, churning, or provisioning. For this reason, the performance of a connector that displays low optical loss when first installed can dramatically degrade after few mating-demating cycles and catastrophic connector failure due to end-face breakage is likely. We present plasma discharge shaping of cleaved fiber tips to strongly improve the endurance of the fibers to repeated mating-demating cycles. We quantify the dependency of the plasma-induced surface curvature of the fiber tip on the plasma duration and on the position of the fiber tip within the plasma cloud. Finally we present data showing the improved endurance of fibers that are exposed to plasma compared to conventional as-cleaved fibers.

  19. Influence of resistance training on cardiorespiratory endurance and muscle power and strength in young athletes.

    PubMed

    Ignjatovic, Aleksandar; Radovanovic, D; Stankovic, R; Marković, Z; Kocic, J

    2011-09-01

    The purpose of this study was to investigate the influence of additional resistance training on cardiorespiratory endurance in young (15.8 ± 0.8 yrs) male basketball players. Experimental group subjects (n=23) trained twice per week for 12 weeks using a variety of general free-weight and machine exercises designed for strength acquisition, beside ongoing regular basketball training program. Control group subject (n=23) participated only in basketball training program. Oxygen uptake (VO(2max)) and related gas exchange measures were determined continuously during maximal exercise test using an automated cardiopulmonary exercise system. Muscle power of the extensors and flexors was measured by a specific computerized tensiometer. Results from the experimental group (VO(2max) 51.6 ± 5.7 ml.min(-1).kg(-1) pre vs. 50.9 ± 5.4 ml.min(-1).kg(-1) post resistance training) showed no change (p>0.05) in cardiorespiratory endurance, while muscle strength and power of main muscle groups increased significantly. These data demonstrate no negative cardiorespiratory performance effects on adding resistance training to ongoing regular training program in young athletes.

  20. Protein Requirements Are Elevated in Endurance Athletes after Exercise as Determined by the Indicator Amino Acid Oxidation Method

    PubMed Central

    Kato, Hiroyuki; Suzuki, Katsuya; Bannai, Makoto; Moore, Daniel R.

    2016-01-01

    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

  1. Does Endurance Training Compensate for Neurotrophin Deficiency Following Diabetic Neuropathy?

    PubMed Central

    Eslami, Rasoul; Gharakhanlou, Reza; Kazemi, Abdolreza; Dakhili, Amir Bahador; Sorkhkamanzadeh, Ghazaleh; Sheikhy, Ayob

    2016-01-01

    Background A lack of neurotrophic support is believed to contribute to the development of diabetic neuropathy. On the other hand, neurotrophins have consistently been shown to increase in the central and peripheral nervous system following exercise, but the effects of exercise intervention on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in diabetic neuropathy are not understood. Objectives This experimental study was designed and carried out at the Tarbiat Modares university (TMU) in Tehran, Iran, to investigate the hypothesis that increased activity as endurance training can help to increase the endogenous expression of neurotrophins in diabetic rats. Methods This was an experimental study with 2 × 2 factorial plans performed at TMU in Iran. Sampling was accidental and 28 adult male Wistar rats in the body mass range of 326.3 ± 8.4 g comprised the sample, with each rat randomly assigned to four groups: diabetic control (DC), diabetic training (DT), healthy control (HC), and healthy training (HT). To induce diabetic neuropathy, after 12 hours of food deprivation, an intraperitoneal injection of streptozotocin (STZ) solution (45 mg/Kg) method was used. Two weeks after STZ injection, the endurance training protocol was performed for 6 weeks; 24 hours after the last training session, the rats were sacrificed. Real-time PCR was used for BDNF and NGF expression. Results The data indicate that diabetes decreases BDNF and NGF expression in sensory (92%, P = 0.01; 90%, P = 0.038, respectively) and motor (93%, P = 0.05; 60%, P = 0.029, respectively) roots. However, NGF mRNA levels in the DT group were significantly higher than in the HC group ((7.1-fold), P = 0.01; (2.2-fold), P = 0.001, respectively, for sensory and motor roots), but this was not shown for BDNF. In addition, endurance training can increase NGF expression in healthy rats ((7.4-fold), P = 0.01; (3.8-fold), P = 0.001, respectively, for sensory and motor roots). Conclusions This

  2. Effect of ACTN3 gene on strength and endurance in soccer players.

    PubMed

    Pimenta, Eduardo M; Coelho, Daniel B; Veneroso, Christiano E; Barros Coelho, Ering J; Cruz, Izinara R; Morandi, Rodrigo F; De A Pussieldi, Guilherme; Carvalho, Maria R S; Garcia, Emerson S; De Paz Fernández, José A

    2013-12-01

    Sports efficiency in activities in which strength and speed are the determining factors has been associated to the ACTN3 gene, which is responsible for the expression of α-actinin-3. Soccer is a mainly aerobic sport because of its long duration, but the acute actions that define the game demand a lot of strength and speed. The purpose of the present study was to compare the performance capacity of soccer players with different genotype groups of ACTN3 (XX, RX, and RR) in strength, speed, and endurance tests. Two hundred professional players of Brazilian soccer first division teams participated in this study. Speed, jump, and endurance test results were compared with the polymorphisms of the ACTN3 gene. It was noticed that RR individuals spent less time to run a 10-m path, compared with XX individuals (p < 0.05). The RR individuals also presented lower time rates at the 20- and 30-m path, compared with RX and XX individuals (p < 0.05). In jump tests, RR individuals presented higher rates, compared with RX and XX individuals (p < 0.05). As for aerobic tests, the XX individuals presented higher rates of V[Combining Dot Above]O2 max, compared with the RR group (p < 0.05), and did not differ from the RX group. The main conclusion of this study is that soccer players of genotype ACTN3/RR are the fastest in short distances and present higher jump potential. ACTN3/XX individuals presented the highest aerobic capacity. These findings can be used in training load adjustment and can influence the development of tactical schemes in soccer matches.

  3. Explosive strength and endurance adaptations in young elite soccer players during two soccer seasons

    PubMed Central

    Visca, Christiano

    2017-01-01

    The purpose of the present study was to investigate the explosive strength and endurance adaptations in young elite soccer players who underwent a supervised training program for a period of two years. Nineteen players, with seven years of training experience (age: 13.3 ± 0.1 years; body weight: 57.9 ± 4.9 kg; height: 168.9 ± 4.7 cm; BMI: 20.1 ± 1.1 kg/m2), voluntarily participated in the present study. The testing sessions were performed at the beginning of the preparation period in the first (T1), second (T2), and third year (T3). The following performance variables were measured: explosive strength [squat-jump (SJ) and counter-movement-jump (CMJ)], pre-stretch augmentation (CMJ-SJ), leg stiffness [hopping test (HT)], short sprint performance [15 m (SSP15) and 30 m (SSP30)], aerobic endurance [test of Leger (VO2max)], maximal heart rate [at the last step of Leger (HR)], and speed-strength endurance [continuous counter-movement-jumps (CCMJ)]. A significant main effect on the VO2Max (+5.72%; F(2.49) = 3.822; p = 0.029; ES = 1.00), HR (-1.70%; F(2.54) = 3.472; p = 0.038; ES = 0.97), CCMJ (+7.64%; F(2.54) = 5.438; p = 0.007; ES = 1.15), SJ (+10.26%; F(2.54) = 15.254; p = 0.0001; ES = 1.53), CMJ (+7.36; F(2.54) = 8.270; p = 0.001; ES = 1.33), HT (+8.34%; F(2.48) = 3.297; p = 0.046; ES = 1.01), SSP15 (-3.50%; F(2.44) = 12.760; p = 0.0001; ES = 1.53), and SSP30 (-4.44%; F(2.44) = 5.797; p = 0.006; ES = 1.16) was observed in the two soccer seasons. These results highlight that, in long-term training, the monitoring of the adaptive responses in relation to the training load may provide a guideline to optimize the trainability of some performance variables in young elite soccer players (13–15 years). In the present study, we cannot exclude the influence of growth and maturation on some performance variables; therefore, the monitored adaptive responses should be considered as the possible results of an interaction between the applied training load and maturation. PMID

  4. Explosive strength and endurance adaptations in young elite soccer players during two soccer seasons.

    PubMed

    Di Giminiani, Riccardo; Visca, Christiano

    2017-01-01

    The purpose of the present study was to investigate the explosive strength and endurance adaptations in young elite soccer players who underwent a supervised training program for a period of two years. Nineteen players, with seven years of training experience (age: 13.3 ± 0.1 years; body weight: 57.9 ± 4.9 kg; height: 168.9 ± 4.7 cm; BMI: 20.1 ± 1.1 kg/m2), voluntarily participated in the present study. The testing sessions were performed at the beginning of the preparation period in the first (T1), second (T2), and third year (T3). The following performance variables were measured: explosive strength [squat-jump (SJ) and counter-movement-jump (CMJ)], pre-stretch augmentation (CMJ-SJ), leg stiffness [hopping test (HT)], short sprint performance [15 m (SSP15) and 30 m (SSP30)], aerobic endurance [test of Leger (VO2max)], maximal heart rate [at the last step of Leger (HR)], and speed-strength endurance [continuous counter-movement-jumps (CCMJ)]. A significant main effect on the VO2Max (+5.72%; F(2.49) = 3.822; p = 0.029; ES = 1.00), HR (-1.70%; F(2.54) = 3.472; p = 0.038; ES = 0.97), CCMJ (+7.64%; F(2.54) = 5.438; p = 0.007; ES = 1.15), SJ (+10.26%; F(2.54) = 15.254; p = 0.0001; ES = 1.53), CMJ (+7.36; F(2.54) = 8.270; p = 0.001; ES = 1.33), HT (+8.34%; F(2.48) = 3.297; p = 0.046; ES = 1.01), SSP15 (-3.50%; F(2.44) = 12.760; p = 0.0001; ES = 1.53), and SSP30 (-4.44%; F(2.44) = 5.797; p = 0.006; ES = 1.16) was observed in the two soccer seasons. These results highlight that, in long-term training, the monitoring of the adaptive responses in relation to the training load may provide a guideline to optimize the trainability of some performance variables in young elite soccer players (13-15 years). In the present study, we cannot exclude the influence of growth and maturation on some performance variables; therefore, the monitored adaptive responses should be considered as the possible results of an interaction between the applied training load and maturation.

  5. Effects of plyometric training on maximal-intensity exercise and endurance in male and female soccer players.

    PubMed

    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

    2016-01-01

    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.

  6. Combined speed endurance and endurance exercise amplify the exercise-induced PGC-1α and PDK4 mRNA response in trained human muscle.

    PubMed

    Skovgaard, Casper; Brandt, Nina; Pilegaard, Henriette; Bangsbo, Jens

    2016-07-01

    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.

  7. THE EFFICACY OF AN EIGHT-WEEK CORE STABILIZATION PROGRAM ON CORE MUSCLE FUNCTION AND ENDURANCE: A RANDOMIZED TRIAL

    PubMed Central

    Sperier, Aubrey D.; Hopkins, Colleen F.; Griffiths, Bridgette D.; Principe, Molly F.; Schnall, Barri L.; Bell, Johanna C.; Koppenhaver, Shane L.

    2016-01-01

    ABSTRACT Background Body armor is credited with increased survival rates in soldiers but the additional axial load may negatively impact the biomechanics of the spine resulting in low back pain. Multiple studies have found that lumbar stabilization programs are superior to generalized programs for patients with chronic low back pain. It is not known if such programs produce objective changes in trunk muscle function with wear of body armor. Hypothesis/Purpose An eight-week core stability exercise program would result in a larger improvement in physical endurance and abdominal muscle thickness than a control intervention. The purpose of this study was to assess the effectiveness of an eight-week core stability exercise program on physical endurance and abdominal muscle thickness with and without wear of body armor. Study Design Randomized controlled trial Methods Participants (N = 33) were randomized into either the core strengthening exercise group or the control group. Testing included ultrasound imaging of abdominal muscle thickness in hook-lying and standing with and without body armor and timed measures of endurance. Results There were statistically significant group by time interactions for transversus abdominis muscle contraction thickness during standing, both with (p = 0.018) and without body armor (p = 0.038). The main effect for hold-time during the horizontal side-support (p = 0.016) indicated improvement over time regardless of group. There was a significant group by time interaction (p = 0.014) for horizontal side-support hold-time when compliance with the exercise protocol was set at 85%, indicating more improvement in the core stabilization group than in the control group. Conclusion Performing an eight-week core stabilization exercise program significantly improves transversus abdominis muscle activation in standing and standing with body armor. When compliant with the exercises, such a program may increase trunk strength and

  8. Effects of acute supplementation of L-arginine and nitrate on endurance and sprint performance in elite athletes.

    PubMed

    Sandbakk, Silvana Bucher; Sandbakk, Øyvind; Peacock, Oliver; James, Philip; Welde, Boye; Stokes, Keith; Böhlke, Nikolai; Tjønna, Arnt Erik

    2015-08-01

    This study examined the effects of acute supplementation with L-arginine and nitrate on running economy, endurance and sprint performance in endurance-trained athletes. In a randomised cross-over, double-blinded design we compared the effects of combined supplementation with 6 g L-arginine and 614 mg nitrate against 614 mg nitrate alone and placebo in nine male elite cross-country skiers (age 18 ± 0 years, VO2max 69.3 ± 5.8 ml ⋅ min(-1) ⋅ kg(-1)). After a 48-hour standardisation of nutrition and exercise the athletes were tested for plasma nitrate and nitrite concentrations, blood pressure, submaximal running economy at 10 km ⋅ h(-1) and 14 km ⋅ h(-1) at 1% incline and 180 m as well as 5-km time-trial running performances. Plasma nitrite concentration following L-arginine + nitrate supplementation (319 ± 54 nmol ⋅ L(-1)) did not differ from nitrate alone (328 ± 107 nmol ⋅ L(-1)), and both were higher than placebo (149 ± 64 nmol ⋅ L(-1), p < 0.01). There were no differences in physiological responses during submaximal running or in 5-km performance between treatments. The plasma nitrite concentrations indicate greater nitric oxide availability both following acute supplementation of L-arginine + nitrate and with nitrate alone compared to placebo, but no additional effect was revealed when L-arginine was added to nitrate. Still, there were no effects of supplementation on exercise economy or endurance running performance in endurance-trained cross-country skiers.

  9. Endurance capacity and high-intensity exercise performance responses to a high fat diet.

    PubMed

    Fleming, Jesse; Sharman, Matthew J; Avery, Neva G; Love, Dawn M; Gómez, Ana L; Scheett, Timothy P; Kraemer, William J; Volek, Jeff S

    2003-12-01

    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.

  10. The effects of elevated pain inhibition on endurance exercise performance

    PubMed Central

    Waddington, Gordon; Keegan, Richard J.; Thompson, Kevin G.; Cathcart, Stuart

    2017-01-01

    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

  11. Cortical thickness and low insight into symptoms in enduring schizophrenia.

    PubMed

    Emami, Seema; Guimond, Synthia; Mallar Chakravarty, M; Lepage, Martin

    2016-01-01

    Poor insight is a common, multidimensional phenomenon in patients with schizophrenia, associated with poorer outcomes and treatment non-adherence. Yet scant research has investigated the neuronal correlates of insight into symptoms (IS), a dimension of insight that may be particularly significant in enduring schizophrenia. Sixty-six patients with enduring schizophrenia (duration >4years) and 33 healthy controls completed MRI scanning and IQ, depression, and anxiety assessments. The Scale to Assess Insight-Expanded (SAI-E) measured insight into patients' four most prominent symptoms and patients were classified into two groups: low IS (0-2; n=33), and high IS (>2; n=33). We evaluated the association between cortical thickness (CT) and insight into symptoms using two methods: (1) a between-patients region-of-interest analysis in the insula, superior temporal gyrus (STG) and frontal lobe; and (2) a whole-brain exploratory regression between patient and controls. Brain regions were segmented using a neuroanatomical atlas and vertex-wise CT analyses were conducted with CIVET, covaried for age and sex. ROI analysis revealed thinner insula cortex in patients with low IS (p<0.05, surviving FDR correction). Patients with low IS also showed significantly thinner right insula, STG, and parahippocampal cortex compared to healthy controls (p<0.05, surviving FDR correction). Regions of observed CT reductions have been hypothesized to subserve self-monitoring, error awareness, and ability to identify hallucinations. Results highlight an important association between right insula abnormalities and impaired IS in schizophrenia. The diverse clinical presentation of patients further suggests an independent relationship between symptomology and insight-related differences in CT that has been previously unexplored in enduring schizophrenia.

  12. Pre-exercise hypervolemia and cycle ergometer endurance in men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Looft-Wilson, R.; Wisherd, J. L.; McKenzie, M. A.; Jensen, C. D.; Whittam, J. H.

    1997-01-01

    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.

  13. Measurement of quadriceps endurance by fNIRS

    NASA Astrophysics Data System (ADS)

    Erdem, Devrim; Şayli, Ömer; Karahan, Mustafa; Akin, A.

    2006-02-01

    In this paper, the changes in muscle deoxygenation trends during a sustained isometric quadriceps (chair squat/half squat) endurance exercise were evaluated among twelve male subjects and the relationship between muscle oxygenation and endurance times was investigated by means of functional near-infrared spectroscopy (fNIRS). Neuromuscular activation and predictions of muscle performance decrements during extended fatiguing task was investigated by means of surface electromyography (sEMG). The results of the study showed that in the subjects who maintained exercise longer than five minutes (group 1), mean Hb recovery time (33 [sec.]) was 37.4% less than the others (group 2, 52.7 [sec.]). Also mean HbO II decline amplitude (2.53 [a.u.] in group 1 and 2.07 [a.u.] in group 2) and oxy decline amplitude (8.4 [a.u.] in group 1 and 3.04 [a.u.] in group 2) in the beginning of squat exercise are found to be 22.6% and 176.9% bigger in these group. For the EMG parameters, mean slope of MNF and MDF decline are found to be 57.5% and 42.2% bigger in magnitude in group 2 which indicates higher degree of decrement in mean and median frequencies although their mean squat duration time is less. This indicates higher index of fatigue for this group. It is concluded that training leads to altered oxygenation and oxygen extraction capability in the exercising muscle and investigated fNIRS parameters could be used for endurance evaluation.

  14. Excellent oxidation endurance of boron nitride nanotube field electron emitters

    SciTech Connect

    Song, Yenan; Song, Yoon-Ho; Milne, William I.; Jin Lee, Cheol

    2014-04-21

    Boron nitride nanotubes (BNNTs) are considered as a promising cold electron emission material owing to their negative electron affinity. BNNT field emitters show excellent oxidation endurance after high temperature thermal annealing of 600 °C in air ambient. There is no damage to the BNNTs after thermal annealing at a temperature of 600 °C and also no degradation of field emission properties. The thermally annealed BNNTs exhibit a high maximum emission current density of 8.39 mA/cm{sup 2} and show very robust emission stability. The BNNTs can be a promising emitter material for field emission devices under harsh oxygen environments.

  15. War leaves an enduring legacy in combatants' lives.

    PubMed

    Smith, Barbara; Parsons, Matthew; Hand, Jennifer

    2014-01-01

    The memory of combat experience endures in World War II veterans. As veterans age, traumatic memory that previously may have been suppressed in the busyness of family and everyday life can re-emerge. Combat stress may affect not only the veterans, but also those people closely associated with them. Interviews were conducted with World War II veteran aircrew, wives, children, grandchildren, siblings, and friends to examine the impact of combat experience on the veterans and the family across the life course from the perspectives of the various participants. The combat experience significantly affected the life course of most.

  16. Plasma biochemistry alterations in horses during an endurance ride.

    PubMed

    Rose, R J; Purdue, R A; Hensley, W

    1977-07-01

    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.

  17. Advanced technology for extended endurance alkaline fuel cells

    NASA Astrophysics Data System (ADS)

    Sheibley, D. W.; Martin, R. A.

    Advanced components have been developed for alkaline fuel cells with a view to the satisfaction of NASA Space Station design requirements for extended endurance. The components include a platinum-on-carbon catalyst anode, a potassium titanate-bonded electrolyte matrix, a lightweight graphite electrolyte reservoir plate, a gold-plated nickel-perforated foil electrode substrate, a polyphenylene sulfide cell edge frame material, and a nonmagnesium cooler concept. When incorporated into the alkaline fuel cell unit, these components are expected to yield regenerative operation in a low earth orbit Space Station with a design life greater than 5 years.

  18. Advanced technology for extended endurance alkaline fuel cells

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W.; Martin, R. A.

    1987-01-01

    Advanced components have been developed for alkaline fuel cells with a view to the satisfaction of NASA Space Station design requirements for extended endurance. The components include a platinum-on-carbon catalyst anode, a potassium titanate-bonded electrolyte matrix, a lightweight graphite electrolyte reservoir plate, a gold-plated nickel-perforated foil electrode substrate, a polyphenylene sulfide cell edge frame material, and a nonmagnesium cooler concept. When incorporated into the alkaline fuel cell unit, these components are expected to yield regenerative operation in a low earth orbit Space Station with a design life greater than 5 years.

  19. Diverse patterns of myocardial fibrosis in lifelong, veteran endurance athletes

    PubMed Central

    O'Hanlon, R.; Prasad, S.; Deighan, A.; MacMillan, P.; Oxborough, D.; Godfrey, R.; Smith, G.; Maceira, A.; Sharma, S.; George, K.; Whyte, G.

    2011-01-01

    This study examined the cardiac structure and function of a unique cohort of documented lifelong, competitive endurance veteran athletes (>50 yr). Twelve lifelong veteran male endurance athletes [mean ± SD (range) age: 56 ± 6 yr (50–67)], 20 age-matched veteran controls [60 ± 5 yr; (52–69)], and 17 younger male endurance athletes [31 ± 5 yr (26–40)] without significant comorbidities underwent cardiac magnetic resonance (CMR) imaging to assess cardiac morphology and function, as well as CMR imaging with late gadolinium enhancement (LGE) to assess myocardial fibrosis. Lifelong veteran athletes had smaller left (LV) and right ventricular (RV) end-diastolic and end-systolic volumes (P < 0.05), but maintained LV and RV systolic function compared with young athletes. However, veteran athletes had a significantly larger absolute and indexed LV and RV end-diastolic and systolic volumes, intraventricular septum thickness during diastole, posterior wall thickness during diastole, and LV and RV stroke volumes (P < 0.05), together with significantly reduced LV and RV ejection fractions (P < 0.05), compared with veteran controls. In six (50%) of the veteran athletes, LGE of CMR indicated the presence of myocardial fibrosis (4 veteran athletes with LGE of nonspecific cause, 1 probable previous myocarditis, and 1 probable previous silent myocardial infarction). There was no LGE in the age-matched veteran controls or young athletes. The prevalence of LGE in veteran athletes was not associated with age, height, weight, or body surface area (P > 0.05), but was significantly associated with the number of years spent training (P < 0.001), number of competitive marathons (P < 0.001), and ultraendurance (>50 miles) marathons (P < 0.007) completed. An unexpectedly high prevalence of myocardial fibrosis (50%) was observed in healthy, asymptomatic, lifelong veteran male athletes, compared with zero cases in age-matched veteran controls and young athletes. These data suggest a

  20. Whole-body fat oxidation increases more by prior exercise than overnight fasting in elite endurance athletes.

    PubMed

    Andersson Hall, Ulrika; Edin, Fredrik; Pedersen, Anders; Madsen, Klavs

    2016-04-01

    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.

  1. Respiratory muscle endurance after training in athletes and non-athletes: A systematic review and meta-analysis.

    PubMed

    Sales, Ana Tereza do N; Fregonezi, Guilherme A de F; Ramsook, Andrew H; Guenette, Jordan A; Lima, Illia Nadinne D F; Reid, W Darlene

    2016-01-01

    The objectives of this systematic review was to evaluate the effects of respiratory muscle training (RMT) on respiratory muscle endurance (RME) and to determine the RME test that demonstrates the most consistent changes after RMT. Electronic searches were conducted in EMBASE, MEDLINE, COCHRANE CENTRAL, CINHAL and SPORTDiscus. The PEDro scale was used for quality assessment and meta-analysis were performed to compare effect sizes of different RME tests. Twenty studies met the inclusion criteria. Isocapnic hyperpnea training was performed in 40% of the studies. Meta-analysis showed that RMT improves RME in athletes (P = 0.0007) and non-athletes (P = 0.001). Subgroup analysis showed differences among tests; maximal sustainable ventilatory capacity (MSVC) and maximal sustainable threshold loading tests demonstrated significant improvement after RMT (P = 0.007; P = 0.003 respectively) compared to the maximal voluntary ventilation (MVV) (P = 0.11) in athletes whereas significant improvement after RMT was only shown by MSVC in non-athletes. The effect size of MSVC was greater compared to MVV in studies that performed both tests. The meta-analysis results provide evidence that RMT improves RME in athletes and non-athletes and MSVC test that examine endurance over several minutes are more sensitive to improvement after RMT.

  2. The ENDURANCE (Environmentally Non-Disturbing Under-ice Robotic ANtarctic Explorer) project. (Invited)

    NASA Astrophysics Data System (ADS)

    Doran, P. T.; Stone, B.; Priscu, J. C.

    2010-12-01

    ENDURANCE (Environmentally Non-Disturbing Under-ice Robotic ANtarctic Explorer) has completed two field seasons working in perennially ice-covered Lake Bonney. Our new data set for West Lake Bonney includes unprecedented hi-resolution sonar maps of the entire lake including through the connecting channel and into East Lake Bonney, 3D (at 100 m xy and subcentimeter z resolution) temperature, conductivity, pH, REDOX, photosynthetically-active radiation, chl-a fluorometry, turbidity and dissolved organic matter. The drop sonde science package also includes a bottom imager which collected 100’s of images of the benthic microbial community. An upward looking camera on the vehicle itself captured information on sediment distribution in the ice cover, which in conjunction with the PAR measurements will be used to generate whole lake photosynthesis models. Variation in ice thickness across the lake was acquired both by sonar and pressure transducer readings while the vehicle was at rest under the ice. A forward looking camera in conjunction with swath sonar was used to confirm the location of the grounding line of Taylor Glacier at the west end of the lake. Our preliminary assessment of the data suggests that the depth of the grounding line coincides with anomalous water characteristics near the glacier face, suggesting either a subglacial discharge or some previously undocumented mixing phenomenon. Our project tested two central hypotheses: H1: The low kinetic energy of the system (diffusion dominates the spatial transport of constituents) produces an ecosystem and ecosystem limits that vary significantly in three dimensions. H2: The whole-lake physical and biogeochemical structure remains static from year to year. Our results can be used to accept H1, and reject H2. Addressing either of these hypotheses would have been near impossible without the ENDURANCE vehicle. The data generated and conclusions drawn have advanced our knowledge of the lake ecosystems in the dry

  3. Maximal Strength Training Improves Surfboard Sprint and Endurance Paddling Performance in Competitive and Recreational Surfers.

    PubMed

    Coyne, Joseph O C; Tran, Tai T; Secomb, Josh L; Lundgren, Lina E; Farley, Oliver R L; Newton, Robert U; Sheppard, Jeremy M

    2017-01-01

    Coyne, JOC, Tran, TT, Secomb, JL, Lundgren, LE, Farley, ORL, Newton, RU, and Sheppard, JM. Maximal strength training improves surfboard sprint and endurance paddling performance in competitive and recreational surfers. J Strength Cond Res 31(1): 244-253, 2017-Upper-body (UB) strength has very high correlations with faster surfboard paddling speeds. However, there is no research examining the effects of improving UB strength has on surfboard paddling ability. This study aimed to determine the influence that improvements in UB closed-kinetic chain maximal strength have on surfboard paddling in both competitive and recreational surfers. Seventeen competitive and recreational male surfers (29.7 ± 7.7 years, 177.4 ± 7.4 cm, 76.7 ± 9.9 kg) participated in a repeated-measures, parallel control study design. Anthropometry; 5-, 10-, and 15-m sprint; and 400-m endurance surfboard paddling tests along with pull-up and dip 1 repetition maximum strength tests were assessed pre- and postintervention. Subjects in the training group performed 5 weeks of maximal strength training in the pull-up and dip. Differences between the training and control groups were examined postintervention. The training group increased their speed over the 5-, 10-, and 15-m sprint, whereas the control group became slower (d = 0.71, 0.51, and 0.4, respectively). The training group also displayed faster endurance paddling performance compared with the control group (d = 0.72). Short-term exposure to maximal strength training elicits improvements in paddling performance measures. However, the magnitude of performance increases seems to be dependent on initial strength levels with differential responses between strong and weaker athletes. Although a longer maximal strength training period may have produced more significant paddling improvements in stronger subjects, practitioners are unlikely to have any more than 5 weeks in an uninterrupted block with competitive surfing athletes. This study reveals

  4. Effect of Additional Respiratory Muscle Endurance Training in Young Well-Trained Swimmers

    PubMed Central

    Lemaitre, Frédéric; Coquart, Jérémy B.; Chavallard, Florence; CASTRES, Ingrid; MUCCI, Patrick; Costalat, Guillaume; Chollet, Didier

    2013-01-01

    While some studies have demonstrated that respiratory muscle endurance training (RMET) improves performances during various exercise modalities, controversy continues about the transfer of RMET effects to swimming performance. The objective of this study was to analyze the added effects of respiratory muscle endurance training (RMET; normocapnic hyperpnea) on the respiratory muscle function and swimming performance of young well-trained swimmers. Two homogenous groups were recruited: ten swimmers performed RMET (RMET group) and ten swimmers performed no RMET (control group). During the 8-week RMET period, all swimmers followed the same training sessions 5-6 times/week. Respiratory muscle strength and endurance, performances on 50- and 200-m trials, effort perception, and dyspnea were assessed before and after the intervention program. The results showed that ventilatory function parameters, chest expansion, respiratory muscle strength and endurance, and performances were improved only in the RMET group. Moreover, perceived exertion and dyspnea were lower in the RMET group in both trials (i.e., 50- and 200-m). Consequently, the swim training associated with RMET was more effective than swim training alone in improving swimming performances. RMET can therefore be considered as a worthwhile ergogenic aid for young competitive swimmers. Key Points Respiratory muscle endurance training improves the performance. Respiratory muscle endurance training improves the ventilatory function parameters, chest expansion, respiratory muscle strength and endurance. Respiratory muscle endurance training decreases the perceived exertion and dyspnea. Respiratory muscle endurance training can be considered as a worthwhile ergogenic aid for young competitive swimmers. PMID:24421721

  5. Effect of additional respiratory muscle endurance training in young well-trained swimmers.

    PubMed

    Lemaitre, Frédéric; Coquart, Jérémy B; Chavallard, Florence; Castres, Ingrid; Mucci, Patrick; Costalat, Guillaume; Chollet, Didier

    2013-01-01

    While some studies have demonstrated that respiratory muscle endurance training (RMET) improves performances during various exercise modalities, controversy continues about the transfer of RMET effects to swimming performance. The objective of this study was to analyze the added effects of respiratory muscle endurance training (RMET; normocapnic hyperpnea) on the respiratory muscle function and swimming performance of young well-trained swimmers. Two homogenous groups were recruited: ten swimmers performed RMET (RMET group) and ten swimmers performed no RMET (control group). During the 8-week RMET period, all swimmers followed the same training sessions 5-6 times/week. Respiratory muscle strength and endurance, performances on 50- and 200-m trials, effort perception, and dyspnea were assessed before and after the intervention program. The results showed that ventilatory function parameters, chest expansion, respiratory muscle strength and endurance, and performances were improved only in the RMET group. Moreover, perceived exertion and dyspnea were lower in the RMET group in both trials (i.e., 50- and 200-m). Consequently, the swim training associated with RMET was more effective than swim training alone in improving swimming performances. RMET can therefore be considered as a worthwhile ergogenic aid for young competitive swimmers. Key PointsRespiratory muscle endurance training improves the performance.Respiratory muscle endurance training improves the ventilatory function parameters, chest expansion, respiratory muscle strength and endurance.Respiratory muscle endurance training decreases the perceived exertion and dyspnea.Respiratory muscle endurance training can be considered as a worthwhile ergogenic aid for young competitive swimmers.

  6. Evaluation of fitness level by the oxygen uptake efficiency slope after a short-term intermittent endurance training.

    PubMed

    Mourot, L; Perrey, S; Tordi, N; Rouillon, J D

    2004-02-01

    Several indicators are used as indices of cardiorespiratory reserve. Among them, oxygen uptake (VO(2)) at peak and ventilatory threshold (VAT) levels are the most common used. In the present study, endurance training was used to evaluate and compare the usefulness of a new index, the Oxygen Uptake Efficiency Slope (OUES) as an alternative to the previous ones. Fifteen physical education student women participated in the study (8 as a trained group [T: age (mean +/- SD) 21.9 +/- 3.3 y, height 165.1 +/- 5.5 cm, weight 60.4 +/- 3.3 kg] and 7 as a control group [C: age 21.7 +/- 1.9 y, height 165.4 +/- 7.2 cm, weight 59.6 +/- 8.6 kg]). Before and after 6 weeks of the Square-Wave Endurance Exercise Test (SWEET) training program or daily activities, they performed an incremental test (30 W/3 min) on a cycle ergometer to determined VO(2), power output and parameters associated with breathing efficiency (the respiratory equivalents, and the ventilatory dead space to tidal volume ratio [Vd/Vt]) at peak- and VAT-levels. The slope of the relationship between ventilation and carbon dioxide production was also calculated. OUES, derived from the logarithmic relationship between VO(2) and minute ventilation (V(E)), was determined at 75 % (OUES75), 90 % (OUES90) and 100 % (OUES100) of exercise duration. After endurance training in T, VO(2) and power output were significantly improved at peak- and VAT-levels while all breathing efficiency indices remained unchanged. No changes were observed in C after 6 weeks. Despite significant correlation between OUES values and VO(2) at peak- and VAT-levels, OUES75, OUES90 and OUES100 did not significantly change after endurance training. While VO(2) and power output at peak- and VAT-levels increased in all T, training-induced changes in OUES appeared more variable. We concluded that OUES was not sufficiently sensitive to highlight improvement of cardiorespiratory reserve after endurance training whereas VO(2) at peak and VAT levels did.

  7. Induced biases in emotional interpretation influence stress vulnerability and endure despite changes in context.

    PubMed

    Mackintosh, Bundy; Mathews, Andrew; Yiend, Jenny; Ridgeway, Valerie; Cook, Emma

    2006-09-01

    Previous research has shown that interpretation biases can be experimentally induced and endure for 24 hours. In two experiments, we show that induced biases not only persist but survive changes in environmental context, including transferring to different rooms with different experimenters. In one experiment, training and testing materials were also presented in different sensory modalities without significantly reducing the magnitude of the induced bias. Furthermore, we found evidence of changes in emotional vulnerability, congruent with the direction of induced bias, which also persisted for 24 hours. Together with earlier results, these findings show that induced biases generalize over contexts and have persisting emotional consequences, suggesting that appropriately adapted training methods may contribute to developing therapeutic techniques within clinical settings.

  8. 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

    PubMed Central

    2013-01-01

    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

  9. Creatine, arginine alpha-ketoglutarate, amino acids, and medium-chain triglycerides and endurance and performance.

    PubMed

    Little, Jonathan P; Forbes, Scott C; Candow, Darren G; Cornish, Stephen M; Chilibeck, Philip D

    2008-10-01

    Creatine (Cr) supplementation increases muscle mass, strength, and power. Arginine a-ketoglutarate (A-AKG) is a precursor for nitric oxide production and has the potential to improve blood flow and nutrient delivery (i.e., Cr) to muscles. This study compared a commercial dietary supplement of Cr, A-AKG, glutamine, taurine, branched-chain amino acids, and medium-chain triglycerides with Cr alone or placebo on exercise performance and body composition. Thirty-five men (approximately 23 yr) were randomized to Cr + A-AKG (0.1 g . kg(-1) . d(-1) Cr + 0.075 g . kg(-1) . d(-1)A-AKG, n = 12), Cr (0.1 g . kg(-1) . d(-1), n = 11), or placebo (1 g . kg(-1) . d(-1) sucrose, n = 12) for 10 d. Body composition, muscle endurance (bench press), and peak and average power (Wingate tests) were measured before and after supplementation. Bench-press repetitions over 3 sets increased with Cr + A-AKG (30.9 +/- 6.6 +/- 34.9 +/- 8.7 reps; p < .01) and Cr (27.6 +/- 5.9 +/- 31.0 +/- 7.6 reps; p < .01), with no change for placebo (26.8 +/- 5.0 +/- 27.1 +/- 6.3 reps). Peak power significantly increased in Cr + A-AKG (741 +/- 112 +/- 794 +/- 92 W; p < .01), with no changes in Cr (722 +/- 138 +/- 730 +/- 144 W) and placebo (696 +/- 63 +/- 705 +/- 77 W). There were no differences in average power between groups over time. Only the Cr-only group increased total body mass (79.9 +/- 13.0 +/- 81.1 +/- 13.8 kg; p < .01), with no significant changes in lean-tissue or fat mass. These results suggest that Cr alone and in combination with A-AKG improves upper body muscle endurance, and Cr + A-AKG supplementation improves peak power output on repeated Wingate tests.

  10. Korean mistletoe (Viscum album coloratum) extract improves endurance capacity in mice by stimulating mitochondrial activity.

    PubMed

    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

    2012-07-01

    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.

  11. The effect of endurance running training on asthmatic adults.

    PubMed Central

    Freeman, W; Nute, M G; Williams, C

    1989-01-01

    Nine mild to moderate asthmatic adults (three males, six females) and six non-asthmatics (one male, five females) underwent endurance running training three times per week for five weeks, at self selected running speeds on a motorized treadmill. After training, the asthmatic group had a significantly higher maximum oxygen uptake, significantly lower blood lactate and heart rate in submaximal running, and significantly reduced time to complete a two mile treadmill run, partly attributable to the ability to exercise at a higher % VO2 max after training. These training induced changes of the asthmatic group were generally of a greater magnitude than those shown by the non-asthmatic group. Although seven of the nine asthmatics did show a reduction in the post-exercise fall in FEV1 after the five week training period, this was not statistically significant for the asthmatic group as a whole. The results of this study therefore suggest that endurance running training can improve the aerobic fitness of asthmatic adults, and may reduce the severity of exercise-induced asthma. PMID:2605441

  12. Enduring Personality Changes after Intense Stressful Event: Case Report

    PubMed Central

    Arsova, Slavica; Manusheva, Nensi; Kopacheva-Barsova, Gabriela; Bajraktarov, Stojan

    2016-01-01

    BACKGROUND World statistical data show that a large number of individuals suffer from posttraumatic stress disorder (PTSD) after exposure to the intense traumatic event. PTSD can have a chronic course with enduring changes in the functioning of the person. CASE PRESENTATION Here we report two adult individuals of different gender and education who were exposed to the extremely severe stressful event after which difficulties in psychological functioning developed. The first case we present is a 46-year-old man, with completed high education, divorced, father of two children, who lives with his parents, and is retired. Disorders appeared 20 years ago when he was exposed to extremely severe stressful events in war circumstances that included captivity, torture, and loss of fellow soldiers. The second case is a 50-year-old female patient, with a university degree, professor of art, married, and mother of two children of whom the son died six years ago. She suffered from disorders after the sudden injury of her son that ended with his death. CONCLUSION Posttraumatic stress disorder after the intense stress is a risk of development enduring personality changes with serious individual and social consequences. PMID:27703573

  13. Speed and Endurance Do Not Trade Off in Phrynosomatid Lizards.

    PubMed

    de Albuquerque, Ralph Lacerda; Bonine, Kevin E; Garland, Theodore

    2015-01-01

    Trade-offs are a common focus of study in evolutionary biology and in studies of locomotor physiology and biomechanics. A previous comparative study of 12 species of European lacertid lizards found a statistically significant negative correlation between residual locomotor speed and stamina (controlling for variation in body size), consistent with ideas about trade-offs in performance based on variation in muscle fiber type composition and other subordinate traits. To begin examining the generality of this finding in other groups of squamates, we measured maximal sprint running speed on a high-speed treadmill and endurance at 1.0 km/h (0.28 m/s) in 14 species of North American phrynosomatid lizards, plus a sample of nine additional species to encompass some of the broadscale diversity of lizards. We used both conventional and phylogenetically informed regression analyses to control for some known causes of performance variation (body size, stockiness, body temperature) and then computed residual performance values. We found no evidence for a trade-off between speed and endurance among the 14 phrynosomatids or among the 23 species in the extended data set. Possible explanations for the apparent difference between lacertids and phrynosomatids are discussed.

  14. Endurance training, overtraining and baroreflex sensitivity in female athletes.

    PubMed

    Uusitalo, A L; Uusitalo, A J; Rusko, H K

    1998-11-01

    We examined heavy training-induced changes in baroreflex sensitivity, plasma volume and resting heart rate and blood pressure variability in female endurance athletes. Nine athletes (experimental training group, ETG) increased intense training (70-90% VO2max) volume by 130% and low-intensity training (< 70% Vo2max) volume by 100% during 6-9 weeks, whereas the corresponding increases in six control athletes (CG) were 5% and 10% respectively. Maximal oxygen uptake (VO2max) in the ETG and CG did not change, but in five ETG athletes VO2max decreased from 53.0 +/- 2.2 (mean +/- SEM) (CI 46.8-59.2) ml kg-1 min-1 to 50.2 +/- 2.3 (43.8-56.6) ml kg-1 min-1 (P < 0.01), indicating overtraining. Baroreflex sensitivity (BRS) measured using the phenylephrine technique and blood pressure variability (BPV) did not change, but the low-frequency power of the R-R interval variability increased in the ETG (P < 0.05). The relative change in plasma volume was 7% in the ETG and 3% in the CG. The changes in BRS did not correlate with the changes in plasma volume, heart rate variability and BPV. We conclude that heavy endurance training and overtraining did not change baroreflex sensitivity or BPV but significantly increased the low-frequency power of the R-R interval variability during supine rest in female athletes as a marker of increased cardiac sympathetic modulation.

  15. On the Use of Enduring Features Analysis for Protected Areas Planning

    NASA Astrophysics Data System (ADS)

    Gill, Cara Raegahn

    The pressures upon natural systems as a result of resource extraction, agriculture and increasing urbanisation has placed pressure on nations on how best to protect remaining wilderness areas. One of the many challenges facing nations is not only how to protect these places, but which areas to protect. There has been a movement to emphasize protection of landscapes and biotic communities based on Enduring Features Gap Analysis instead of on individual populations. This analytical technique is based on unique units of soil and landform. This is a coarse filter conservation strategy, which relies on geographical information systems (GIS) and satellite technologies, and on the idea of representation. In 1990 Manitoba adopted enduring features gap analysis as part of its Protected Areas Initiative (PAI). Enduring features are assumed to be a surrogate for biodiversity, with the idea that by protecting a portion of all enduring features within a region, all biotic community types will be represented. These assumptions can be misleading, biological features do not necessarily coincide with the underlying enduring features. The purpose of this thesis is to determine what differences may exist between vegetation communities as defined by the enduring features. This will help determine the effectiveness of enduring features gap analysis as a surrogate for biological diversity, and its effectiveness as a representative criteria of gap analysis. A botanical survey was conducted within Chitek Lake Park Reserve, a protected area located 350 km northwest of Winnipeg. Within three enduring features, different biological communities were selected for the vegetation survey, and within each survey site a soil pit was dug. A total of76 sites were surveyed in three different enduring features. A Digital Elevation Model (DEM) was also used to compare and contrast geophysical landforms, vegetation communities and enduring features. Canonical Correlation Analysis (CCA) and Principal

  16. LSA field test

    NASA Technical Reports Server (NTRS)

    Jaffe, P.

    1980-01-01

    After almost four years of endurance testing of photovoltaic modules, no fundamental life-limiting mechanisms were identified that could prevent the twenty-year life goal from being met. The endure data show a continual decline in the failure rate with each new large-scale procurement. Cracked cells and broken interconnects continue to be the principal causes of failure. Although the modules are more adversely affected physically by hot, humid environments than by cool or dry environments there are insufficient data to correlate failure with environment. There is little connection between the outward physical condition of a module and changes in its electrical performance.

  17. A vacuum (10(exp -9) Torr) friction apparatus for determining friction and endurance life of MoSx films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Honecy, Frank S.; Abel, Phillip B.; Pepper, Stephen V.; Spalvins, Talivaldis; Wheeler, Donald R.

    1992-01-01

    The first part of this paper describes an ultrahigh vacuum friction apparatus (tribometer). The tribometer can be used in a ball-on-disk configuration and is specifically designed to measure the friction and endurance life of solid lubricating films such as MoS(x) in vacuum at a pressure of 10 exp -7 Pa. The sliding mode is typically unidirectional at a constant rotating speed. The second part of this paper presents some representative friction and endurance life data for magnetron sputtered MoS(x) films (110 nm thick) deposited on sputter-cleaned 440 C stainless-steel disk substrates, which were slid against a 6-mm-diameter 440 C stainless-steel bearing ball. All experiments were conducted with loads of 0.49 to 3.6 N (average Hertzian contact pressure, 0.33 to 0.69 GPa), at a constant rotating speed of 120 rpm (sliding velocity ranging from 31 to 107 mm/s due to the range of wear track radii involved in the experiments), in a vacuum of 7 x 10 exp -7 Pa and at room temperature. The results indicate that there are similarities in friction behavior of MoS(x) films overs their life cycles regardless of load applied. The coefficient of friction (mu) decreases as load W increases according to mu = kW exp -1/3. The endurance life E of MoS(x) films decreases as the load W increases according to E = KW exp -1.4 for the load range. The load- (or contract-pressure-) dependent endurance life allows us to reduce the time for wear experiments and to accelerate endurance life testing of MoS(x) films. For the magnetron-sputtered MoS(x) films deposited on 440 C stainless-steel disks: the specific wear rate normalized to the load and the number of revolutions was 3 x 10 exp -8 mm exp 3/N-revolution; the specific wear rate normalized to the load and the total sliding distance was 8 x 10 exp -7 mm exp 3/N-m; and the nondimensional wear coefficient of was approximately 5 x 10 exp -6. The values are almost independent of load in the range 0.49 to 3.6 N (average Hertzian contact

  18. Integrated mRNA and miRNA expression profiling in blood reveals candidate biomarkers associated with endurance exercise in the horse.

    PubMed

    Mach, Núria; Plancade, Sandra; Pacholewska, Alicja; Lecardonnel, Jérôme; Rivière, Julie; Moroldo, Marco; Vaiman, Anne; Morgenthaler, Caroline; Beinat, Marine; Nevot, Alizée; Robert, Céline; Barrey, Eric

    2016-03-10

    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.

  19. Integrated mRNA and miRNA expression profiling in blood reveals candidate biomarkers associated with endurance exercise in the horse

    PubMed Central

    Mach, Núria; Plancade, Sandra; Pacholewska, Alicja; Lecardonnel, Jérôme; Rivière, Julie; Moroldo, Marco; Vaiman, Anne; Morgenthaler, Caroline; Beinat, Marine; Nevot, Alizée; Robert, Céline; Barrey, Eric

    2016-01-01

    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

  20. Effects of morning versus evening combined strength and endurance training on physical performance, muscle hypertrophy, and serum hormone concentrations.

    PubMed

    Küüsmaa, Maria; Schumann, Moritz; Sedliak, Milan; Kraemer, William J; Newton, Robert U; Malinen, Jari-Pekka; Nyman, Kai; Häkkinen, Arja; Häkkinen, Keijo

    2016-12-01

    This study investigated the effects of 24 weeks of morning versus evening same-session combined strength (S) and endurance (E) training on physical performance, muscle hypertrophy, and resting serum testosterone and cortisol diurnal concentrations. Forty-two young men were matched and assigned to a morning (m) or evening (e) E + S or S + E group (mE + S, n = 9; mS + E, n = 9; eE + S, n = 12; and eS + E, n = 12). Participants were tested for dynamic leg press 1-repetition maximum (1RM) and time to exhaustion (Texh) during an incremental cycle ergometer test both in the morning and evening, cross-sectional area (CSA) of vastus lateralis and diurnal serum testosterone and cortisol concentrations (0730 h; 0930 h; 1630 h; 1830 h). All groups similarly increased 1RM in the morning (14%-19%; p < 0.001) and evening (18%-24%; p < 0.001). CSA increased in all groups by week 24 (12%-20%, p < 0.01); however, during the training weeks 13-24 the evening groups gained more muscle mass (time-of-day main effect; p < 0.05). Texh increased in all groups in the morning (16%-28%; p < 0.01) and evening (18%-27%; p < 0.001), however, a main effect for the exercise order, in favor of E + S, was observed on both testing times (p < 0.051). Diurnal rhythms in testosterone and cortisol remained statistically unaltered by the training order or time. The present results indicate that combined strength and endurance training in the evening may lead to larger gains in muscle mass, while the E + S training order might be more beneficial for endurance performance development. However, training order and time seem to influence the magnitude of adaptations only when the training period exceeded 12 weeks.

  1. Changes in selected biochemical, muscular strength, power, and endurance measures during deliberate overreaching and tapering in rugby league players.

    PubMed

    Coutts, A; Reaburn, P; Piva, T J; Murphy, A

    2007-02-01

    The purpose of this study was to examine the influence of overreaching on muscle strength, power, endurance and selected biochemical responses in rugby league players. Seven semi-professional rugby league players (.VO(2max) = 56.1 +/- 1.7 mL . kg (-1) . min (-1); age = 25.7 +/- 2.6 yr; BMI = 27.6 +/- 2.0) completed 6 weeks of progressive overload training with limited recovery periods. A short 7-day stepwise reduction taper immediately followed the overload period. Measures of muscular strength, power and endurance and selected biochemical parameters were taken before and after overload training and taper. Multistage fitness test running performance was significantly reduced (12.3 %) following the overload period. Although most other performance measures tended to decrease following the overload period, only peak hamstring torque at 1.05 rad . s (-1) was significantly reduced (p < 0.05). Following the taper, a significant increase in peak hamstring torque and isokinetic work at both slow (1.05 rad . s (-1)) and fast (5.25 rad . s (-1)) movement velocities were observed. Minimum clinically important performance decreases were measured in a multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) following the overload period. Following the taper, minimum clinically important increases in the multistage fitness test, vertical jump, 3-RM squat and 3-RM bench press and chin-up (max) and 10-m sprint performance were observed. Compared to resting measures, the plasma testosterone to cortisol ratio, plasma glutamate, plasma glutamine to glutamate ratio and plasma creatine kinase activity demonstrated significant changes at the end of the overload training period (p < 0.05). These results suggest that muscular strength, power and endurance were reduced following the overload training, indicating a state of overreaching. The most likely explanation for the decreased performance is increased muscle damage via a decrease in the anabolic

  2. The Relationship between Selected Body Composition Variables and Muscular Endurance in Women

    ERIC Educational Resources Information Center

    Esco, Michael R.; Olson, Michele S.; Williford, Henry N.

    2010-01-01

    The primary purpose of this study was to determine if muscular endurance is affected by referenced waist circumference groupings, independent of body mass and subcutaneous abdominal fat, in women. This study also explored whether selected body composition measures were associated with muscular endurance. Eighty-four women were measured for height,…

  3. Analysis of the Static Strength and Relative Endurance of Women Athletes

    ERIC Educational Resources Information Center

    Heyward, Vivian; McCreary, Leslie

    1977-01-01

    Investigations of static strength and relative endurance of the grip muscles of women athletes revealed that mean endurance time was significantly greater than for men. Results were discussed in light of evidence suggesting possible sex differences in muscle hypertrophy, capillarization of muscle tissue, critical occluding tension level, and…

  4. Neuromuscular and cardiovascular adaptations during concurrent strength and endurance training in untrained men.

    PubMed

    Mikkola, J; Rusko, H; Izquierdo, M; Gorostiaga, E M; Häkkinen, K

    2012-09-01

    This study examined the effects of concurrent strength and endurance training on neuromuscular and endurance characteristics compared to strength or endurance training alone. Previously untrained men were divided into strength (S: n=16), endurance (E: n=11) or concurrent strength and endurance (SE: n=11) training groups. S and E trained 2 times and SE 2 + 2 times a week for strength and endurance during the 21-week period. Maximal unilateral isometric and bilateral concentric forces of leg muscles increased similarly in S and SE by 20-28% (p<0.01) and improvements in isometric forces were accompanied by increases (p<0.05) of maximal muscle activation. Rate of force development of isometric action (p<0.05) improved only in S. The increase in muscle cross-sectional area of the quadriceps femoris in SE (11%, p<0.001) were greater than in S (6%, p<0.001) or in E (2%, p<0.05). SE and E increased maximal cycling power (SE: 17% and E: 11%, p<0.001) and VO(2MAX) (SE: 17%, p<0.001 and E: 5%, ns.). These results suggest that the present moderate volume 21-week concurrent SE training in previously untrained men optimizes the magnitude of muscle hypertrophy, maximal strength and endurance development, but interferes explosive strength development, compared with strength or endurance training alone.

  5. 77 FR 25536 - Surety Companies Acceptable On Federal Bonds: Endurance American Insurance Company

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-30

    ... Fiscal Service Surety Companies Acceptable On Federal Bonds: Endurance American Insurance Company AGENCY.... 9305 to the following company: Endurance American Insurance Company (NAIC 10641). Business Address: 333... subsequent annual renewal as long as the companies remain qualified (see 31 CFR part 223). A list...

  6. Menstrual Cycle Effects on Anaerobic Power, Muscular Strength, and Muscular Endurance in Trained and Untrained Females.

    ERIC Educational Resources Information Center

    Rosenburg, Beth S.; And Others

    A study determined if anaerobic power, isometric strength, and isometric endurance are affected by the menstrual cycle and if endurance trained females and untrained females are affected in the same manner on these performance parameters. Subjects were healthy, normally menstruating females, ages 18-34 years who were classified as either trained…

  7. Relationships of Muscular Endurance Among Specific Muscle Groups for Continuous and Intermittent Static Contractions.

    ERIC Educational Resources Information Center

    Hoshizaki, Thomas B.; Massey, B. H.

    1986-01-01

    The static contraction endurance characteristics of five muscle groups were investigated in 38 normal, health, college-aged men. Four parameters of continuous and intermittent contractions were examined. Results support the hypothesis that endurance is unique to each muscle group and specific to the task performed. (Author/MT)

  8. Methazolamide Plus Aminophylline Abrogates Hypoxia-Mediated Endurance Exercise Impairment.

    PubMed

    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

    2015-12-01

    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.

  9. Local muscular endurance and prediction of 1 repetition maximum for bench in 4 athletic populations.

    PubMed

    Desgorces, François D; Berthelot, Geoffroy; Dietrich, Gilles; Testa, Marc S A

    2010-02-01

    The aim of this study was to determine a predictive equation of 1 repetition maximum (1RM) from local muscular endurance. Different athletic male populations were assessed: racket/ball games players (n = 31), power lifters (n = 22), swimmers (n = 28), and rowers (n = 29). After the 1RM assessment for the bench press, the maximum number of repetitions (MNR) relative to the 1RM (85%, 75%, 60%, 40%, and 20%) was tested. No significant differences in strength evolution from 20% to 100% of the 1RM was found between power lifters and racket/ball games players and between swimmers and rowers. However, differences in the strength evolution appeared between these 2 mixed groups (p < 0.01), with differences appearing from 75% of 1RM to lesser relative strength (p < 0.05). Nonlinear equations fitted best with the actual data for the capacity to repeat lifts. The evolution of strength from 100% to 20% of 1RM was better described when the groups' specific equations were used as demonstrated by r, and residuals range between the predicted minus the measured 1RM. The strength endurance competences for high loads (100%-75%) were adequately modelled by the equation based on the total population. The accuracy of the 1RM prediction was better when a reduced number of lifts was performed. For untrained or novice subjects, the use of group-specific equations for the all evolutionary profile of strength allows a good estimate of 1RM and provides adequate numbers of lifts for all levels of strength, thus optimizing the training programs.

  10. Urine concentrations of oral salbutamol in samples collected after intense exercise in endurance athletes.

    PubMed

    Hostrup, Morten; Kalsen, Anders; Auchenberg, Michael; Rzeppa, Sebastian; Hemmersbach, Peter; Bangsbo, Jens; Backer, Vibeke

    2014-06-01

    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.

  11. Nonsteroidal Anti-Inflammatory Drug Use and Endurance During Running in Male Long-Distance Runners

    PubMed Central

    Da Silva, Eduardo; Pinto, Ronei S.; Cadore, Eduardo L.; Kruel, Luiz F.

    2015-01-01

    Context: The effect of ibuprofen on pain tolerance during exercise is controversial, and its effects on endurance performance have been poorly investigated. Objective: To investigate the effect of prophylactic administration of the nonsteroidal anti-inflammatory drug ibuprofen on the time until the self-report of fatigue (tlim) in runners with exercise-induced muscle damage. Design: Randomized controlled clinical trial. Setting: Laboratory. Patients or Other Participants: Twenty healthy male long-distance runners (age = 18.8 ± 0.4 years, maximal oxygen consumption = 55.5 ± 5.9 mL·kg−1·min−1). Intervention(s): Participants were assigned to 2 groups (ibuprofen group = 10, placebo group = 10) to perform tlim trials (speed corresponded to their previously determined secondventilatory thresholds) 48 hours before and 48 hours after the induction of a lower limb muscle-damage protocol (isokinetic dynamometry). One hour before the second tlim trial, the ibuprofen group received 1.2 g ibuprofen, and the placebo group received lactose orally. Main Outcome Measure(s): Time until self-reported fatigue, heart rate, respiratory quotient, oxygen consumption, and perceived exertion were recorded during each tlim test. Results: Both groups reported increases in muscle pain in the knee extensors and flexors 48 hours after the muscle-damage protocol. We observed a reduction in the endurance performance of both groups (P < .01) but no difference between groups (P = .55). Conclusions: Ibuprofen did not reduce the effect of muscle damage and pain on performance. Prophylactic use of nonsteroidal anti-inflammatory drugs did not have an ergogenic effect on running performance after exercise-induced muscle damage in male long-distance runners. PMID:25622243

  12. Endurance or resistance training in primary care after in-patient rehabilitation for COPD?

    PubMed

    Skumlien, Siri; Aure Skogedal, Ellen; Skrede Ryg, Morten; Bjørtuft, Øystein

    2008-03-01

    Resistance (RT) and endurance training (ET) prescribed by a rehabilitation centre and carried out under the supervision of primary care physiotherapists after the completion of 4 weeks of multidisciplinary in-patient pulmonary rehabilitation (IPR) were compared regarding capacity to induce further health effects. After IPR, 40 chronic obstructive pulmonary disease (COPD) patients were allocated to RT or ET twice weekly for 12 weeks. Primary outcome variables were walking capacity (treadmill endurance time, TET; 6-min walking distance, 6MWD), functional status (Glittre ADL-test; Hyrim Physical Activity Questionnaire) and health-related quality of life (HRQOL) (St. George's Respiratory Questionnaire, SGRQ). Body functions variables were included as secondary outcome measures. HRQOL and physical activity were reinvestigated after 1 year. Median attendance rates were not different between RT (21, interquartile range [17;23]) and ET (22 [18;24]). Both groups improved in TET (RT 7.7 min 95% CI {3.6;12}, ET 5.7 min {1.7;9.8}). 6MWD increased significantly after ET (46 m {20;72}). Functional status was unchanged. SGRQ tended to further improve after RT (-3.2{-7.4;1.2}), while ET maintained the improvement gained during IPR. Body functions measures changed according to training modality. After 1 year, a majority of patients in both groups were exercising regularly, but SGRQ was significantly better than pre-IPR only in the RT group (-7.9{-14.3;-1.5}). We conclude that supervised RT or ET twice weekly sustains and improves the effects of IPR. With no large differences detected between the two training modalities, the choice of training may be guided by individual needs, patient preferences and the availability of equipment.

  13. Effect of prolonged exercise on muscle citrate concentration before and after endurance training in men.

    PubMed

    Coggan, A R; Spina, R J; Kohrt, W M; Holloszy, J O

    1993-02-01

    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.

  14. Energetics of endurance exercise in young horses determined by nuclear magnetic resonance metabolomics.

    PubMed

    Luck, Margaux M; Le Moyec, Laurence; Barrey, Eric; Triba, Mohamed N; Bouchemal, Nadia; Savarin, Philippe; Robert, Céline

    2015-01-01

    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.

  15. Energetics of endurance exercise in young horses determined by nuclear magnetic resonance metabolomics

    PubMed Central

    Luck, Margaux M.; Le Moyec, Laurence; Barrey, Eric; Triba, Mohamed N.; Bouchemal, Nadia; Savarin, Philippe; Robert, Céline

    2015-01-01

    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

  16. Reliability of a Novel High Intensity One Leg Dynamic Exercise Protocol to Measure Muscle Endurance

    PubMed Central

    Lepers, Romuald; Marcora, Samuele M.

    2016-01-01

    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

  17. Reference Values for Inspiratory Muscle Endurance in Healthy Children and Adolescents

    PubMed Central

    Woszezenki, Cristhiele Taís; Heinzmann-Filho, João Paulo; Vendrusculo, Fernanda Maria; Piva, Taila Cristina; Levices, Isadora; Donadio, Márcio Vinícius Fagundes

    2017-01-01

    Aims To generate reference values for two inspiratory muscle endurance (IME) protocols in healthy children and adolescents. Materials and methods This is an observational, cross-sectional study, in healthy children and adolescents from 4 to 18 years of age. Weight, height, maximal inspiratory pressure (MIP) and IME were measured using two protocols. A fixed load of 30% of MIP with a 10% increment every 2 minutes was used in the incremental threshold loading protocol. As for the maximal loading protocol, a fixed load of 70% of MIP was used and the time limit (Tlim) achieved until fatigue was measured. Results A total of 462 participants were included, 281 corresponding to the incremental loading protocol and 181 to maximal loading. There were moderate and positive correlations between IME and age, MIP, weight and height in the incremental threshold loading. However, the regression model demonstrated that MIP and age were the best variables to predict the IME. Otherwise, weak and positive correlations with age, weight and height were found in the maximal loading. Only age and height influenced endurance in the regression model. The predictive power (r2) of the incremental threshold loading protocol was 0.65, while the maximal loading was 0.15. The reproducibility measured by the intraclass correlation coefficient (ICC) was higher in the incremental loading (0.96) compared to the maximal loading test (0.69). Conclusion IME in healthy children and adolescents can be explained by age, height and MIP. The incremental threshold loading protocol showed more reliable results and should be the model of choice to evaluate IME in the pediatric age group. PMID:28122012

  18. Changes in plasma taurine levels after different endurance events.

    PubMed

    Ward, R J; Francaux, M; Cuisinier, C; Sturbois, X; De Witte, P

    1999-01-01

    The sulphonated amino acid taurine increased significantly in the plasma of trained athletes after three endurance exercises of different duration and intensity, a 90 min run on a treadmill at 75% of an individual's VO2 peak, a Marathon, 42.2 km and a 100 km run, by 19%, 77% and 36%, respectively. Such results indicated that the speed at which the exercise is performed, referred to as the intensity, rather than the duration of the exercise, correlated with the elevated taurine levels possibly indicating its release from muscle fibres. The plasma amino acid pool decreased significantly in relationship with the duration of the exercise, caused by their utilisation for glucogenesis. The possible sources of the increased plasma taurine are discussed.

  19. Muscle strength and endurance following lowerlimb suspension in man

    NASA Technical Reports Server (NTRS)

    Tesch, Per A.; Berg, Hans E.; Haggmark, Tom; Ohlsen, Hans; Dudley, Gary A.

    1991-01-01

    The effect of lower-limb suspension on the muscle strength and muscle endurance was investigated in six men subjected to four weeks of unilateral unloading of a lower limb (using of a harness attached to a modified shoe), followed by seven weeks of weight-bearing recovery. Results showed a decrease in the cross-sectional area (CSA) of the thigh muscle and in the average peak torque (APT) during three bouts of 30 concentric knee extensions. While the the thigh muscle CSA returned to normal after seven weeks of recovery, the APT recovery was still reduced by 11 percent, suggesting that muscle metabolic function was severely affected by unloading and was not restored by ambulation.

  20. Relationship between membrane Cl− conductance and contractile endurance in isolated rat muscles

    PubMed Central

    de Paoli, Frank Vincenzo; Broch-Lips, Martin; Pedersen, Thomas Holm; Nielsen, Ole Bækgaard

    2013-01-01

    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

  1. T helper cell cytokine profiles after endurance exercise.

    PubMed

    Kakanis, Michael W; Peake, Jonathan; Brenu, Ekua W; Simmonds, Michael; Gray, Bon; Marshall-Gradisnik, Sonya M

    2014-09-01

    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.

  2. Evidence for mild thyroidal impairment in women undergoing endurance training

    SciTech Connect

    Boyden, T.W.; Pamenter, R.W.; Stanforth, P.; Rotkis, T.; Wilmore, J.H.

    1982-01-01

    The effects of endurance training on body composition and the pituitary-thyroid axis were studied in 29 healthy, young (mean age, 28.7 yr), regularly menstruating women. Women who were initially jogging a mean of 13.5 miles/week were selected for this study to minimize dropouts. Body composition, measured by hydrostatic weighing, and nonfasting plasma concentrations of T/sub 4/, T/sub 3/, rT/sub 3/, TSH, and TRH-stimulated TSH, measured by RIA, were examined initially and after each subject's weekly mileage had increased to 30 miles (..delta..30, mean total body weight did not change, mean fat weight decreased (-1.02 kg/ P<0.005), and mean lean weight increased (+0.75 kg; P<0.05). T/sub 4/ and unstimulated TSH did not change. However, mean (+/- SE) T/sub 3/ decreased from 107.2 +/- 4.4 to 97.9 +/- 3.4 ng/dl (P<0.025), and mean rT/sub 3/ decreased from 170.9 +/- 13.9 to 154.6 +/- 13.2 pg/ml (P<0.025). The decrease in T/sub 3/ and rT/sub 3/ were accompanied by significantly greater TSH responses to TRH stimulation (mean (+/- SE) area under TSH curve, 1381.4 +/- 123 vs. 1712.8 +/- 202 ..mu..IU/ml-min; P < 0.01). These results indicate that physically active women who undergo additional endurance training 1) become more lean without a change in total body weight, and 2) have changes in T/sub 3/, rT/sub 3/, and TRH-stimulated TSH indicative of mild thyroidal impairment.

  3. Reproductive profile of physically active men after exhaustive endurance exercise.

    PubMed

    Vaamonde, D; Da Silva, M E; Poblador, M S; Lancho, J L

    2006-09-01

    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.

  4. Building a beverage for recovery from endurance activity: a review.

    PubMed

    Spaccarotella, Kim J; Andzel, Walter D

    2011-11-01

    Recovery beverages are commonly used by endurance and team-sport athletes during the time between exercise sessions. Practical recommendations on the optimal nutrient composition of these drinks and timing of their consumption are therefore needed. This article summarizes research to date on the use of recovery beverages after aerobic activities and provides the following recommendations for practitioners on the optimal formula and timing of use for endurance and team-sport athletes. Current evidence suggests that, to maximize glycogen resynthesis, athletes should consume about 1.2 g carbohydrate per kilogram body weight as glucose and sucrose immediately after exercise and each hour thereafter for 4-6 hours postexercise. Alternatively, they may consume 0.8 g·kg(-1)·h(-1) in combination with 0.4 g·kg(-1)·h(-1) amino acids or protein. Liquids provide valuable fluids for rehydration, and an ideal recovery beverage should not only contain carbohydrate and protein but also contain electrolytes, including about 0.3-0.7 g sodium·per liter fluid to help restore sodium lost through sweat. Commercial beverages with this type of nutrient composition are effective, and recent work indicates that chocolate milk may be as effective as or superior to these in promoting recovery. Research regarding the effects of specific types of amino acids and antioxidants on recovery is mixed; thus, further investigation is needed before specific recommendations about these nutrients can be made. Future studies that include women and athletes representing a variety of sports, ages, and training levels and that use consistent methodology will lead to a better understanding of the effects of postexercise intake on recovery.

  5. Lipid peroxidation and antioxidative vitamins under extreme endurance stress.

    PubMed

    Rokitzki, L; Logemann, E; Sagredos, A N; Murphy, M; Wetzel-Roth, W; Keul, J

    1994-06-01

    The aim of this study was to examine whether extreme endurance stress of trained athletes can influence lipid peroxidation and muscle enzymes. A randomized and placebo-controlled study was carried out on 24 trained long-distance runners who were substituted with alpha-tocopherol (400 I.U. d-1) and ascorbic acid (200 mg d-1) during 4.5 weeks prior to a marathon race. The serum concentrations of retinol, ascorbic acid, beta-carotene, alpha-tocopherol, malondialdehyde (TBARS) and uric acid as well as glutathione peroxidase (GSH Px) and catalase were measured 4.5 weeks before (A), immediately before (B), immediately after (C) and 24 h after (D) the course. After competition (C) TBARS serum concentrations of the athletes (n = 22) decreased in both groups (P < 0.0001). The ascorbic acid serum concentration increased significantly in the supplemented group from (A) to (B) (P < 0.01), from (B) to (C) (P < 0.001) and in the placebo group a significant increase from (B) to (C) (P < 0.01) was observed. The alpha-tocopherol serum concentration increased significantly in the supplemented group from (A) to (B) (P < 0.001) and from (B) to (C) (P < 0.05). The enzymes glutathione peroxidase (GSH Px) and catalase measured in erythrocytes as well as the serum selenium levels did not show significant differences at any time. A significant increase of CK concentration was observed from (C) to (D) in the supplemented group (P < 0.01) and in the placebo group (P < 0.001). The increase of CK serum concentration is remarkably lower in the supplemented group compared with the placebo group (P < 0.01). It is concluded that endurance training coupled with antioxidant vitamin supplementation reduces blood CK increase under exercise stress.

  6. The Influence of Collective Behavior on Pacing in Endurance Competitions

    PubMed Central

    Renfree, Andrew; Crivoi do Carmo, Everton; Martin, Louise; Peters, Derek M.

    2015-01-01

    A number of theoretical models have been proposed in recent years to explain pacing strategies observed in individual competitive endurance events. These have typically related to the internal regulatory processes that inform the making of decisions relating to muscular work rate. Despite a substantial body of research which has investigated the influence of collective group dynamics on individual behaviors in various animal species, this issue has not been comprehensively studied in individual athletic events. This is somewhat surprising given that athletes often directly compete in close proximity to one another, and that collective behavior has also been observed in other human environments including pedestrian interactions and financial market trading. Whilst the reasons for adopting collective behavior are not fully understood, collective behavior is thought to result from individual agents following simple local rules that result in seemingly complex large systems that act to confer some biological advantage to the collective as a whole. Although such collective behaviors may generally be beneficial, competitive endurance events are complicated by the fact that increasing levels of physiological disruption as activity progresses may compromise the ability of some individuals to continue to interact with other group members. This could result in early fatigue and relative underperformance due to suboptimal utilization of physiological resources by some athletes. Alternatively, engagement with a collective behavior may benefit all due to a reduction in the complexity of decisions to be made and a subsequent reduction in cognitive loading and mental fatigue. This paper seeks evidence for collective behavior in previously published analyses of pacing behavior and proposes mechanisms through which it could potentially be either beneficial, or detrimental to individual performance. It concludes with suggestions for future research to enhance understanding of this

  7. Between 21 and 34 years of age, aging alters the catecholamine responses to supramaximal exercise in endurance trained athletes.

    PubMed

    Zouhal, H; Gratas-Delamarche, A; Rannou, F; Granier, P; Bentue-Ferrer, D; Delamarche, P

    1999-08-01

    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.

  8. Comparison of structural response and fatigue endurance of aircraft flap-like box structures subjected to acoustic loading.

    PubMed

    Xiao, Y; White, R G; Aglietti, G S

    2005-05-01

    The results of an extensive test program to characterize the behavior of typical aircraft structures under acoustic loading and to establish their fatigue endurance are presented. The structures tested were the three flap-like box-type of structures. Each structure consisted of one flat (bottom) and one curved (top) stiffener stiffened skin panel, front, and rear spars, and ribs that divided the structures into three bays. The three structures, constructed from three different materials (aircraft standard aluminum alloy, Carbon Fibre Reinforced Plastic, and a Glass Fibre Metal Laminate, i.e., GLARE) had the same size and configuration, with only minor differences due to the use of different materials. A first set of acoustic tests with excitations of intensity ranging from 140 to 160 dB were carried out to obtain detailed data on the dynamic response of the three structures. The FE analysis of the structures is also briefly described and the results compared with the experimental data. The fatigue endurance of the structures was then determined using random acoustic excitation with an overall sound pressure level of 161 dB, and details of crack propagation are reported.

  9. Comparison of structural response and fatigue endurance of aircraft flap-like box structures subjected to acoustic loading

    NASA Astrophysics Data System (ADS)

    Xiao, Y.; White, R. G.; Aglietti, G. S.

    2005-05-01

    The results of an extensive test program to characterize the behavior of typical aircraft structures under acoustic loading and to establish their fatigue endurance are presented. The structures tested were the three flap-like box-type of structures. Each structure consisted of one flat (bottom) and one curved (top) stiffener stiffened skin panel, front, and rear spars, and ribs that divided the structures into three bays. The three structures, constructed from three different materials (aircraft standard aluminum alloy, Carbon Fibre Reinforced Plastic, and a Glass Fibre Metal Laminate, i.e., GLARE) had the same size and configuration, with only minor differences due to the use of different materials. A first set of acoustic tests with excitations of intensity ranging from 140 to 160 dB were carried out to obtain detailed data on the dynamic response of the three structures. The FE analysis of the structures is also briefly described and the results compared with the experimental data. The fatigue endurance of the structures was then determined using random acoustic excitation with an overall sound pressure level of 161 dB, and details of crack propagation are reported. .

  10. Influence of 3 months endurance training on red cell deformability in non insulin dependent type 2 diabetes mellitus patients.

    PubMed

    Ahmad, B; Opitz, D; Bloch, W; Brixius, K

    2013-08-01

    The main purpose of the study was to examine if 3 months of bicycle endurance training alters the red cell deformability in non insulin dependent type 2 diabetes mellitus men.The red cell deformability was measured with the Laser assisted optical rotational cell analyzer. The maximal elongation index and the semimaximal shear stress were measured with the Lineweaver Burke model.At the beginning and the end of the intervention the patients passed a bicycle ergometry test. As a reference group, 13 males without diabetes passed the same testing procedure. Blood samplings were taken before testing, immediately after physical exhaustion and after a 30 min recovery phase.After the training period diabetic patients could significantly reduce BMI, fasting glucose and HbA1c. The reference group had significantly higher elongation indices than the diabetes patients independent from training status. After the training period the basal values of the maximal elongation index did not change significantly. However, maximal elongation indices were significantly reduced after physical examination and in resting time.The semimaximal shear stress of diabetes patients did not alter during the training period. In comparison to the reference group semimaximal shear stress was significantly reduced at all measurement times.This pilot study proves that the maximal elongation index is significantly decreased in diabetes mellitus patients. After 3 months endurance training the red cells become more rigid while the semimaximal shear stress remains constant. Further interventions are required to analyze the exact cause of the presented findings.

  11. Effects of individualized versus group task-oriented circuit training on balance ability and gait endurance in chronic stroke inpatients.

    PubMed

    Kim, Bonggil; Park, Yunjin; Seo, Yonggon; Park, Sangseo; Cho, Hyeyoung; Moon, Hyunghoon; Lee, Haelim; Kim, Myungki; Yu, Jaeho

    2016-06-01

    [Purpose] The purpose of this study was to analyze the effects of task-oriented circuit training on the balance ability and gait endurance of chronic stroke inpatients. [Subjects and Methods] The participants were 30 patients who had stroke >6 months previously, resulting in a disability such as hemiparesis. The participants were randomly divided into the group task-oriented circuit training group and the individual task-oriented circuit-training group. They performed eight types of modified task-oriented training. Balance ability and gait endurance were measured by using the Berg balance scale questionnaire and the 6-min walk test, respectively, before and after the experiment. [Results] Significant differences were observed between before and after the intervention in all variables. There was a significant difference between groups in Berg balance scale scores; however, no significant differences were seen in the timed up and go test and the 6-min walk test. [Conclusion] The results of this study indicated that group exercise can better improve the balance ability of chronic stroke inpatients after stroke than can individualized exercise intervention.

  12. Changes evaluated in soccer-specific power endurance either with or without a 10-week, in-season, intermittent, high-intensity training protocol.

    PubMed

    Siegler, Jason; Gaskill, Steven; Ruby, Brent

    2003-05-01

    The purpose of this study was to evaluate changes in soccer-specific power endurance of 34 female high school soccer players throughout a season either with or without an intermittent, high-intensity exercise protocol. Thirty-four female high school soccer players were tested prior to the 2000 fall season and again 10 weeks later. The tests included an abridged 45-minute shuttle test (LIST), hydrostatic weighing, vertical jump, 20-m running-start sprint, and 30-second Wingate test. The experimental group (EG; n = 17, age 16.5 +/- 0.9 years) completed a 10-week in-season plyometric, resistive training, and high-intensity anaerobic program. The control group (n = 17, age 16.3 +/- 1.4 years) completed only traditional aerobic soccer conditioning. Statistical significance was set at alpha < 0.05. The experimental group showed significant improvements in the LIST (EG = delta 394 seconds +/- 124 seconds), 20-m sprint (EG = Delta-0.10 seconds +/- 0.10 seconds), increase in fat-free mass (EG = delta 1.14 kg +/- 1.22 kg), and decreases in fat mass (EG = Delta-1.40 kg +/- 1.47 kg) comparing pre- to postseason. This study indicates that a strength and plyometric program improved power endurance and speed over aerobic training only. Soccer-specific power endurance training may improve match performance and decrease fatigue in young female soccer players.

  13. Early Parental Positive Behavior Support and Childhood Adjustment: Addressing Enduring Questions with New Methods

    PubMed Central

    Waller, Rebecca; Gardner, Frances; Dishion, Thomas; Sitnick, Stephanie L.; Shaw, Daniel S.; Winter, Charlotte E.; Wilson, Melvin

    2016-01-01

    A large literature provides strong empirical support for the influence of parenting on child outcomes. The current study addresses enduring research questions testing the importance of early parenting behavior to children’s adjustment. Specifically, we developed and tested a novel multi-method observational measure of parental positive behavior support at age 2. Next, we tested whether early parental positive behavior support was related to child adjustment at school age, within a multi-agent and multi-method measurement approach and design. Observational and parent-reported data from mother–child dyads (N = 731; 49 percent female) were collected from a high-risk sample at age 2. Follow-up data were collected via teacher report and child assessment at age 7.5. The results supported combining three different observational methods to assess positive behavior support at age 2 within a latent factor. Further, parents’ observed positive behavior support at age 2 predicted multiple types of teacher-reported and child-assessed problem behavior and competencies at 7.5 years old. Results supported the validity and predictive capability of a multi-method observational measure of parenting and the importance of a continued focus on the early years within preventive interventions. PMID:26997757

  14. Effects of endurance training on the isocapnic buffering and hypocapnic hyperventilation phases in professional cyclists

    PubMed Central

    Chicharro, J.; Hoyos, J.; Lucia, A.

    2000-01-01

    Objectives—To evaluate the changes produced in both the isocapnic buffering and hypocapnic hyperventilation (HHV) phases of professional cyclists (n = 11) in response to endurance training, and to compare the results with those of amateur cyclists (n = 11). Methods—Each professional cyclist performed three laboratory exercise tests to exhaustion during the active rest (autumn: November), precompetition (winter: January), and competition (spring: May) periods of the sports season. Amateur cyclists only performed one exercise test during the competition period. The isocapnic buffering and HHV ranges were calculated during each test and defined as VO2 and power output (W). Results—No significant differences were found in the isocapnic buffering range in each of the periods of the sports season in professional cyclists. In contrast, there was a significant reduction in the HHV range (expressed in W) during both the competition (p<0.01) and precompetition(p<0.05) periods compared with the rest period. On the other hand, a longer HHV range (p<0.01) was observed in amateur cyclists than in professional cyclists (whether this was expressed in terms of VO2 or W). Conclusions—No change is observed in the isocapnic buffering range of professional cyclists throughout a sports season despite a considerable increase in training loads and a significant reduction in HHV range expressed in terms of power output. Key Words: training; cycling; isocapnic buffering; hypocapnic hyperventilation PMID:11131234

  15. Speed versus endurance tradeoff in plants: Leaves with higher photosynthetic rates show stronger seasonal declines.

    PubMed

    Zhang, Yong-Jiang; Sack, Lawren; Cao, Kun-Fang; Wei, Xue-Mei; Li, Nan

    2017-02-10

    We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the general understanding of leaf design, and would simplify models of annual leaf carbon relations. We tested for such a trade-off using a database analysis across vascular plants and using an experimental approach for 29 cycad species, representing an ancient plant lineage with diversified evergreen leaves. In both tests, a higher photosynthetic rate per mass or per area in the favorable season was associated with a stronger absolute or percent decline in the unfavorable season. We resolved a possible mechanism based on biomechanics and nitrogen allocation; cycads with high leaf toughness (leaf mass per area) and higher investment in leaf construction than in physiological function (C/N ratio) tended to have lower warm season photosynthesis but less depression in the cool season. We propose that this trade-off, consistent with cost-benefit theory, represents a significant physio-phenological constraint on the diversity and seasonal dynamics of photosynthetic rate.

  16. Speed versus endurance tradeoff in plants: Leaves with higher photosynthetic rates show stronger seasonal declines

    PubMed Central

    Zhang, Yong-Jiang; Sack, Lawren; Cao, Kun-Fang; Wei, Xue-Mei; Li, Nan

    2017-01-01

    We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the general understanding of leaf design, and would simplify models of annual leaf carbon relations. We tested for such a trade-off using a database analysis across vascular plants and using an experimental approach for 29 cycad species, representing an ancient plant lineage with diversified evergreen leaves. In both tests, a higher photosynthetic rate per mass or per area in the favorable season was associated with a stronger absolute or percent decline in the unfavorable season. We resolved a possible mechanism based on biomechanics and nitrogen allocation; cycads with high leaf toughness (leaf mass per area) and higher investment in leaf construction than in physiological function (C/N ratio) tended to have lower warm season photosynthesis but less depression in the cool season. We propose that this trade-off, consistent with cost-benefit theory, represents a significant physio-phenological constraint on the diversity and seasonal dynamics of photosynthetic rate. PMID:28186201

  17. Early Parental Positive Behavior Support and Childhood Adjustment: Addressing Enduring Questions with New Methods.

    PubMed

    Waller, Rebecca; Gardner, Frances; Dishion, Thomas; Sitnick, Stephanie L; Shaw, Daniel S; Winter, Charlotte E; Wilson, Melvin

    2015-05-01

    A large literature provides strong empirical support for the influence of parenting on child outcomes. The current study addresses enduring research questions testing the importance of early parenting behavior to children's adjustment. Specifically, we developed and tested a novel multi-method observational measure of parental positive behavior support at age 2. Next, we tested whether early parental positive behavior support was related to child adjustment at school age, within a multi-agent and multi-method measurement approach and design. Observational and parent-reported data from mother-child dyads (N = 731; 49 percent female) were collected from a high-risk sample at age 2. Follow-up data were collected via teacher report and child assessment at age 7.5. The results supported combining three different observational methods to assess positive behavior support at age 2 within a latent factor. Further, parents' observed positive behavior support at age 2 predicted multiple types of teacher-reported and child-assessed problem behavior and competencies at 7.5 years old. Results supported the validity and predictive capability of a multi-method observational measure of parenting and the importance of a continued focus on the early years within preventive interventions.

  18. Long Term Materials Test Program. Quarterly report, July-September 1983

    SciTech Connect

    Not Available

    1984-04-01

    Corrosion and erosion/corrosion testing of gas turbine vane and blade base alloys and a variety of protective coating systems under the Long Term Materials Test program has surpassed 3400 hours. The PFBC facility at Malta, New York continues to show an exceptionally high degree of reliability and consistency in performance. Operating conditions include a 1650/sup 0/F bed temperature at 10 atmospheres pressures utilizing Pittsburgh No. 8 coal and a low alkali dolomite sulfur sorbent. After 2687 hours, unprotected nickel and cobalt base vane and blade alloys generally experienced corrosion rates of 1 to 2 mils/1000 hours at metal temperatures of 1100, 1300, and 1500/sup 0/F. Precious metal aluminide and MCrAlY coatings continue to show excellent corrosion resistance (<0.5 mils/1000 hrs) at 1500/sup 0/F, but are susceptible to varying degrees of pitting attack at 1100/sup 0/ and 1300/sup 0/F. Erosion/corrosion degradation rates at 800 to 900 fps., 1350/sup 0/F and less than 100 ppM dust loading ranged from 1 to 4 mils/1000 hours with corrosion predominately concentrated in areas of particle impaction indicating an erosion/corrosion synergism.

  19. Effects of three day bed-rest on circulatory, metabolic and hormonal responses to oral glucose load in endurance trained athletes and untrained subjects

    NASA Technical Reports Server (NTRS)

    Smorawinski, J.; Kubala, P.; Kaciuba-Uociako, H.; Nazar, K.; Titow-Stupnicka, E.; Greenleaf, J. E.

    1996-01-01

    Endurance trained long distance runners and untrained individuals underwent three days of bed rest and oral glucose loading. Before and after bed rest, individuals were given glucose tolerance tests, and their heart rates, blood pressure, blood glucose levels, insulin levels, and catecholamine interactions were measured. Results indicated that glucose tolerance is more affected by bed rest-induced deconditioning in untrained individuals than in trained individuals.

  20. Efficacy of circumferential pulmonary vein ablation of atrial fibrillation in endurance athletes

    PubMed Central

    Calvo, Naiara; Mont, Lluís; Tamborero, David; Berruezo, Antonio; Viola, Graziana; Guasch, Eduard; Nadal, Mercè; Andreu, David; Vidal, Barbara; Sitges, Marta; Brugada, Josep

    2010-01-01

    Aims Long-term endurance sport practice has been increasingly recognized as a risk factor for lone atrial fibrillation (AF). However, data on the outcome of circumferential pulmonary vein ablation (CPVA) in endurance athletes are scarce. The aim of the study was to evaluate the efficacy of CPVA in AF secondary to endurance sport practice. Methods and results Patients submitted to CPVA answered a questionnaire about lifetime history of endurance sport practice. Endurance athletes were defined as those who engaged in >3 h per week of high-intensity exercise for at least the 10 years immediately preceding their AF diagnosis. A series of 182 consecutive patients was included (51 ± 11 years, 65% with paroxysmal AF, 81% men, 42 ± 6 mm mean left atrial diameter); 107 (59%) patients had lone AF, and 42 of them (23% of the study population) were classified as endurance athletes (lone AF sport group). Freedom from arrhythmia after a single CPVA was similar in the lone AF sport group compared with the remaining patients (P = 0.446). Left atrial size and long-standing AF were the only independent predictors for arrhythmia recurrence after ablation. Conclusion Circumferential pulmonary vein ablation was as effective in AF secondary to endurance sport practice as in other aetiologies of AF. PMID:19923171

  1. Performance of high-altitude, long-endurance, turboprop airplanes using conventional or cryogenic fuels

    NASA Technical Reports Server (NTRS)

    Liu, G. C.; Morris, C. E. K., Jr.; Koenig, R. W.

    1983-01-01

    An analytical study has been conducted to evaluate the potential endurance of remotely piloted, low speed, high altitude, long endurance airplanes designed with 1990 technology. The baseline configuration was a propeller driven, sailplane like airplane powered by turbine engines that used JP-7, liquid methane, or liquid hydrogen as fuel. Endurance was measured as the time spent between 60,000 feet and an engine limited maximum altitude of 70,000 feet. Performance was calculated for a baseline vehicle and for configurations derived by varying aerodynamic, structural or propulsion parameters. Endurance is maximized by reducing wing loading and engine size. The level of maximum endurance for a given wing loading is virtually the same for all three fuels. Constraints due to winds aloft and propulsion system scaling produce maximum endurance values of 71 hours for JP-7 fuel, 70 hours for liquid methane, and 65 hours for liquid hydrogen. Endurance is shown to be strongly effected by structural weight fraction, specific fuel consumption, and fuel load. Listings of the computer program used in this study and sample cases are included in the report.

  2. Comparison of resistance and concurrent resistance and endurance training regimes in the development of strength.

    PubMed

    Shaw, Brandon S; Shaw, Ina; Brown, Gregory A

    2009-12-01

    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.

  3. Comparison of effects of strength and endurance training in patients with chronic obstructive pulmonary disease.

    PubMed

    Ortega, Francisco; Toral, Javier; Cejudo, Pilar; Villagomez, Rafael; Sánchez, Hildegard; Castillo, José; Montemayor, Teodoro

    2002-09-01

    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.

  4. The Effect of Two Speed Endurance Training Regimes on Performance of Soccer Players

    PubMed Central

    Iaia, F. Marcello; Fiorenza, Matteo; Perri, Enrico; Alberti, Giampietro; Millet, Grégoire P.; Bangsbo, Jens

    2015-01-01

    In order to better understand the specificity of training adaptations, we compared the effects of two different anaerobic training regimes on various types of soccer-related exercise performances. During the last 3 weeks of the competitive season, thirteen young male professional soccer players (age 18.5±1 yr, height 179.5±6.5 cm, body mass 74.3±6.5 kg) reduced the training volume by ~20% and replaced their habitual fitness conditioning work with either speed endurance production (SEP; n = 6) or speed endurance maintenance (SEM; n = 7) training, three times per wk. SEP training consisted of 6–8 reps of 20-s all-out running bouts followed by 2 min of passive recovery, whereas SEM training was characterized by 6–8 x 20-s all-out efforts interspersed with 40 s of passive recovery. SEP training reduced (p<0.01) the total time in a repeated sprint ability test (RSAt) by 2.5%. SEM training improved the 200-m sprint performance (from 26.59±0.70 to 26.02±0.62 s, p<0.01) and had a likely beneficial impact on the percentage decrement score of the RSA test (from 4.07±1.28 to 3.55±1.01%) but induced a very likely impairment in RSAt (from 83.81±2.37 to 84.65±2.27 s). The distance covered in the Yo-Yo Intermittent Recovery test level 2 was 10.1% (p<0.001) and 3.8% (p<0.05) higher after SEP and SEM training, respectively, with possibly greater improvements following SEP compared to SEM. No differences were observed in the 20- and 40-m sprint performances. In conclusion, these two training strategies target different determinants of soccer-related physical performance. SEP improved repeated sprint and high-intensity intermittent exercise performance, whereas SEM increased muscles’ ability to maximize fatigue tolerance and maintain speed development during both repeated all-out and continuous short-duration maximal exercises. These results provide new insight into the precise nature of a stimulus necessary to improve specific types of athletic performance in trained

  5. The effect of almond consumption on elements of endurance exercise performance in trained athletes

    PubMed Central

    2014-01-01

    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

  6. The Effect of Two Speed Endurance Training Regimes on Performance of Soccer Players.

    PubMed

    Iaia, F Marcello; Fiorenza, Matteo; Perri, Enrico; Alberti, Giampietro; Millet, Grégoire P; Bangsbo, Jens

    2015-01-01

    In order to better understand the specificity of training adaptations, we compared the effects of two different anaerobic training regimes on various types of soccer-related exercise performances. During the last 3 weeks of the competitive season, thirteen young male professional soccer players (age 18.5±1 yr, height 179.5±6.5 cm, body mass 74.3±6.5 kg) reduced the training volume by ~20% and replaced their habitual fitness conditioning work with either speed endurance production (SEP; n = 6) or speed endurance maintenance (SEM; n = 7) training, three times per wk. SEP training consisted of 6-8 reps of 20-s all-out running bouts followed by 2 min of passive recovery, whereas SEM training was characterized by 6-8 x 20-s all-out efforts interspersed with 40 s of passive recovery. SEP training reduced (p<0.01) the total time in a repeated sprint ability test (RSAt) by 2.5%. SEM training improved the 200-m sprint performance (from 26.59±0.70 to 26.02±0.62 s, p<0.01) and had a likely beneficial impact on the percentage decrement score of the RSA test (from 4.07±1.28 to 3.55±1.01%) but induced a very likely impairment in RSAt (from 83.81±2.37 to 84.65±2.27 s). The distance covered in the Yo-Yo Intermittent Recovery test level 2 was 10.1% (p<0.001) and 3.8% (p<0.05) higher after SEP and SEM training, respectively, with possibly greater improvements following SEP compared to SEM. No differences were observed in the 20- and 40-m sprint performances. In conclusion, these two training strategies target different determinants of soccer-related physical performance. SEP improved repeated sprint and high-intensity intermittent exercise performance, whereas SEM increased muscles' ability to maximize fatigue tolerance and maintain speed development during both repeated all-out and continuous short-duration maximal exercises. These results provide new insight into the precise nature of a stimulus necessary to improve specific types of athletic performance in trained young

  7. Effect of Progressive Volume-Based Overload During Plyometric Training on Explosive and Endurance Performance in Young Soccer Players.

    PubMed

    Ramírez-Campillo, Rodrigo; Henríquez-Olguín, Carlos; Burgos, Carlos; Andrade, David C; Zapata, Daniel; Martínez, Cristian; Álvarez, Cristian; Baez, Eduardo I; Castro-Sepúlveda, Mauricio; Peñailillo, Luis; Izquierdo, Mikel

    2015-07-01

    The purpose of the study was to compare the effects of progressive volume-based overload with constant volume-based overload on muscle explosive and endurance performance adaptations during a biweekly short-term (i.e., 6 weeks) plyometric training intervention in young soccer players. Three groups of young soccer players (age 13.0 ± 2.3 years) were divided into: control (CG; n = 8) and plyometric training with (PPT; n = 8) and without (NPPT; n = 8) a progressive increase in volume (i.e., 16 jumps per leg per week, with an initial volume of 80 jumps per leg each session). Bilateral and unilateral horizontal and vertical countermovement jump with arms (CMJA), 20-cm drop jump reactive strength index (RSI20), maximal kicking velocity (MKV), 10-m sprint, change of direction speed (CODS), and Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1) were measured. Although both experimental groups significantly increased CMJA, RSI20, CODS, and endurance performance, only PPT showed a significant improvement in MKV and 10-m sprint time. In addition, only PPT showed a significantly higher performance improvement in jumping, MKV, and Yo-Yo IR1 compared with CG. Also, PPT showed higher meaningful improvement compared with NPPT in all (except 1) jump performance measures. Furthermore, although PPT involved a higher total volume compared with NPPT, training efficiency (i.e., percentage change in performance/total jump volume) was similar between groups. Our results show that PPT and NPPT ensured significant improvement in muscle explosive and endurance performance measures. However, a progressive increase in plyometric training volume seems more advantageous to induce soccer-specific performance improvements.

  8. PPAR-α and PPARGC1A gene variants have strong effects on aerobic performance of Turkish elite endurance athletes.

    PubMed

    Tural, Ercan; Kara, Nurten; Agaoglu, Seydi Ahmet; Elbistan, Mehmet; Tasmektepligil, Mehmet Yalcin; Imamoglu, Osman

    2014-09-01

    The aim of this study was to investigate the effect of PPAR-α intron 7G>C and PPARGC1A gene Gly482Ser polymorphisms on aerobic performance of elite level endurance athletes. This study was carried out on 170 individuals (60 elite level endurance athletes and 110 sedentary controls). Aerobic performance of athletes and sedentary control groups were defined by maximal oxygen uptake capacity. DNA was isolated from peripheral blood using GeneJet Genomic DNA Purification kit. Genotyping of the PPAR-α intron 7G>C and PPARGC1A Gly482Ser polymorphisms was performed using PCR-RFLP methods, and statistical evaluations were carried out using SPSS 15.0. Mean age of athletes were 21.38 ± 2.83 (18-29) and control mean age were 25.92 ± 4.88 (18-35). Mean maximal oxygen consumption of athletes were 42.14 ± 7.6 ml/(kg min) and controls were 34.33 ± 5.43 ml/(kg min). We found statistically significant differences between the athlete and control groups with respect to both PPAR-α and PPARGC1A genotype distributions (p = 0.006, <0.001, respectively) and allele frequencies (<0.001, <0.001, respectively). Additionally, when we examined PPAR-α and PPARGC1A genotype distributions according to the aerobic performance test parameters, we found a statistically significant association between velocity, time and maximal oxygen consumption and PPAR-α and PPARGC1A genotypes (p < 0.001). To our knowledge, this is the first study in Turkey examined PPAR-α intron 7G>C and PPARGC1A Gly482Ser gene polymorphisms in elite level endurance athletes. Our results suggest that PPAR-α and PPARGC1A genes have strong effect on aerobic performance of elit level athletes.

  9. THE RELATIONSHIP BETWEEN THE NUMBER OF REPETITIONS PERFORMED AT GIVEN INTENSITIES IS DIFFERENT IN ENDURANCE AND STRENGTH TRAINED ATHLETES

    PubMed Central

    Richens, B.

    2014-01-01

    Prescribing training intensity and volume is a key problem when designing resistance training programmes. One approach is to base training prescription on the number of repetitions performed at a given percentage of repetition maximum due to the correlation found between these two measures. However, previous research has raised questions as to the accuracy of this method, as the repetitions completed at different percentages of 1RM can differ based upon the characteristics of the athlete. The objective of this study was therefore to evaluate the effect of an athlete's training background on the relationship between the load lifted (as a percentage of one repetition maximum) and the number of repetitions achieved. Eight weightlifters and eight endurance runners each completed a one repetition maximum test on the leg press and completed repetitions to fatigue at 90, 80 and 70% of their one repetition maximum. The endurance runners completed significantly more repetitions than the weightlifters at 70% (39.9 ± 17.6 versus 17.9 ± 2.8; p < 0.05) and 80% (19.8 ± 6.4 versus 11.8 ± 2.7; p < 0.05) of their one repetition maximum but not at 90% (10.8 ± 3.9 versus 7.0 ± 2.1; p > 0.05) of one repetition maximum. These differences could be explained by the contrasting training adaptations demanded by each sport. This study suggests that traditional guidelines may underestimate the potential number of repetitions that can be completed at a given percentage of 1RM, particularly for endurance trained athletes. PMID:24899782

  10. Effects of upper-body sprint-interval training on strength and endurance capacities in female cross-country skiers.

    PubMed

    Vandbakk, Kristine; Welde, Boye; Kruken, Andrea Hovstein; Baumgart, Julia; Ettema, Gertjan; Karlsen, Trine; Sandbakk, Øyvind

    2017-01-01

    This study compared the effects of adding upper-body sprint-intervals or continuous double poling endurance training to the normal training on maximal upper-body strength and endurance capacity in female cross-country skiers. In total, 17 female skiers (age: 18.1±0.8yr, body mass: 60±7 kg, maximal oxygen uptake (VO2max): 3.30±0.37 L.min-1) performed an 8-week training intervention. Here, either two weekly sessions of six to eight 30-s maximal upper-body double poling sprint-intervals (SIG, n = 8) or 45-75 min of continuous low-to-moderate intensity double poling on roller skis (CG, n = 9) were added to their training. Before and after the intervention, the participants were tested for physiological and kinematical responses during submaximal and maximal diagonal and double poling treadmill roller skiing. Additionally, we measured maximal upper-body strength (1RM) and average power at 40% 1RM in a poling-specific strength exercise. SIG improved absolute VO2max in diagonal skiing more than CG (8% vs 2%, p<0.05), and showed a tendency towards higher body-mass normalized VO2max (7% vs 2%, p = 0.07). Both groups had an overall improvement in double poling peak oxygen uptake (10% vs 6% for SIG and CG) (both p<0.01), but no group-difference was observed. SIG improved 1RM strength more than CG (18% vs 10%, p<0.05), while there was a tendency for difference in average power at 40% 1RM (20% vs 14%, p = 0.06). Oxygen cost and kinematics (cycle length and rate) in double poling and diagonal remained unchanged in both groups. In conclusion, our study demonstrates that adding upper-body sprint-interval training is more effective than continuous endurance training in improving upper-body maximal strength and VO2max.

  11. Altered relationship between R-R interval and R-R interval variability in endurance athletes with overtraining syndrome.

    PubMed

    Kiviniemi, A M; Tulppo, M P; Hautala, A J; Vanninen, E; Uusitalo, A L T

    2014-04-01

    Autonomic dysfunction decreases within-subject correlation between R-R interval length (RRi) and vagally mediated RRi variability in cardiac disease. We tested the hypothesis that overtraining syndrome (OTS) may also weaken this relationship. Nine OTS and 10 control endurance athletes underwent 24-h electrocardiogram monitoring, which was repeated in eight OTS and nine control athletes after 6 months, when two OTS athletes still had symptoms of OTS. The power of high-frequency (HF) oscillations of RRi was analyzed in 5-min epochs over the whole recording. Quadratic regression was performed between 5-min values of RRi and log-transformed (ln) HF to obtain R(2) for each recording. The relationship between RRi and HFln was higher in the OTS athletes than controls [R(2): 0.87 (90% confidence interval, CI: 0.84-0.89) vs 0.78 (90% CI: 0.72-0.84); P = 0.034; effect size = 1.22]. Large decrease in R(2) was observed in six recovered OTS athletes after 6 months follow-up [ΔR(2): -0.12 (90% CI: -0.25-0.01); P = 0.11; effect size = 1.44] with no changes in the controls. Mean values of RRi and its variability did not differ between the groups. The within-subject correlation between RRi and vagally mediated RRi variability was stronger in endurance athletes with OTS compared with controls. The present findings may improve the detection of OTS and recovery from OTS in endurance athletes.

  12. Flexible Twist for Pitch Control in a High Altitude Long Endurance Aircraft with Nonlinear Response

    DTIC Science & Technology

    2008-12-01

    Information dominance is the key motivator for employing high-altitude long-endurance (HALE) aircraft to provide continuous coverage in the theaters of operation A joined-wing configuration of such a craft gives the advantage of a platform for higher resolution sensors. Design challenges emerge with structural flexibility that arise from a long-endurance aircraft design. The goal was to demonstrate that scaling the nonlinear response of a full-scale finite element model of a high-altitude long-endurance (HALE) aircraft was possible if the model was aeroelastically and

  13. Endurance and failure characteristics of modified Vasco X-2, CBS 600 and AISI 9310 spur gears. [aircraft construction materials

    NASA Technical Reports Server (NTRS)

    Townsend, D. P.; Zaretsky, E. V.

    1980-01-01

    Gear endurance tests and rolling-element fatigue tests were conducted to compare the performance of spur gears made from AISI 9310, CBS 600 and modified Vasco X-2 and to compare the pitting fatigue lives of these three materials. Gears manufactured from CBS 600 exhibited lives longer than those manufactured from AISI 9310. However, rolling-element fatigue tests resulted in statistically equivalent lives. Modified Vasco X-2 exhibited statistically equivalent lives to AISI 9310. CBS 600 and modified Vasco X-2 gears exhibited the potential of tooth fracture occurring at a tooth surface fatigue pit. Case carburization of all gear surfaces for the modified Vasco X-2 gears results in fracture at the tips of the gears.

  14. 14 CFR 33.43 - Vibration test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the...

  15. 14 CFR 33.43 - Vibration test.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each... configuration of the propeller type which is used for the endurance test, and using, for other engines, the...

  16. Adaptation to a fat-rich diet: effects on endurance performance in humans.

    PubMed

    Helge, J W

    2000-11-01

    The focus of this review is on studies where dietary fat content was manipulated to investigate the potential ergogenic effect of fat loading on endurance exercise performance. Adaptation to a fat-rich diet is influenced by several factors, of which the duration of the adaptation period, the exercise intensity of the performance test and the content of fat and carbohydrate in the experimental diet are the most important. Evidence is presented that short term adaptation, < 6 days, to a fat-rich diet is detrimental to exercise performance. When adaptation to a fat-rich diet was performed over longer periods, studies where performance was tested at moderate intensity, 60 to 80% of maximal oxygen uptake, demonstrate either no difference or an attenuated performance after consumption of a fat-rich compared with a carbohydrate-rich diet. When performance was measured at high intensity after a longer period of adaptation, it was at best maintained, but in most cases attenuated, compared with consuming a carbohydrate-rich diet. Furthermore, evidence is presented that adaptation to a fat-rich diet leads to an increased capacity of the fat oxidative system and an enhancement of the fat supply and subsequently the amount of fat oxidised during exercise. However, in most cases muscle glycogen storage is compromised, and although muscle glycogen breakdown is diminished to a certain extent, this is probably part of the explanation for the lack of performance enhancement after adaptation to a fat-rich diet.

  17. Monitoring hand flexor fatigue in a 24-h motorcycle endurance race.

    PubMed

    Marina, M; Porta, J; Vallejo, L; Angulo, R

    2011-04-01

    Motorcycle riders must endure high levels of muscle tension for long periods of time, especially in their arms and forearms, when steering and using handlebar controls. Because the right hand operates the gas handle and front brakes, the present research focuses on fatigue in the right hand flexors. Ten adult riders, aged 32.5±5.5years, volunteered to participate in this study. During the 24h race each rider, on completion of a relay stage, visited the assessment box to do the following handgrip test sequence: (1) 10s of EMG recording at rest, (2) one 3-s maximal voluntary contraction (MVC), (3) 1min rest interval and (4) 50% MVC maintained during 10s. EMG amplitude (MP: μV) and median and mean frequency (MF and MPF: Hz) over the superficial finger flexors were recorded during the whole handgrip test sequence with adhesive surface electrodes. MVC values were maintained during the first two relays (50-60min duration in total) and dropped gradually thereafter (p<0.01). During the monitoring of the 50% MVC, mean amplitude increased (p=0.024) while median and mean frequency tended to decrease. These results suggest fatigue is produced in motorcycle riders in a 24h race. However, the expected reduction of EMG frequency was not confirmed given to a potentially large variability.

  18. Ventilatory Responses at Peak Exercise in Endurance-Trained Obese Adults

    PubMed Central

    Lorenzo, Santiago

    2013-01-01

    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

  19. Isokinetic and isometric strength-endurance after 6 hours of immersion and 6 degrees head-down tilt in men

    NASA Technical Reports Server (NTRS)

    Shaffer-Bailey, M.; Greenleaf, J. E.; Hutchinson, T. M.

    1996-01-01

    PURPOSE: To determine weight (water) loss levels for onset of muscular strength and endurance changes during deconditioning. METHODS: Seven men (27-40 yr) performed maximal shoulder-, knee-, and ankle-joint isometric (0 degree.s(-1) load) and isokinetic (60 degrees, 120 degrees, 180 degrees.s(-1) velocity) exercise tests during ambulatory control (AC), after 6 h of 6 degrees head-down tilt (HDT; dry-bulb temp. = 23.2 +/- SD 0.6 degrees C, relative humidity = 31.1+/- 11.1%) and after 6 h of 80 degrees foot-down head-out water immersion (WI; water temp. = 35.0 +/- SD 0.1 degree C) treatments. RESULTS: Weight (water) loss after HDT (1.10 +/- SE 0.14 kg, 1.4 +/- 0.2% body wt) and WI (1.54+/- 0.19 kg, 2.0 +/- 0.2% body wt) were not different, but urinary excretion with WI (1,354 +/- 142 ml.6 h(-1)) was 28% greater (p < 0.05) than that of 975 +/- 139 ml.6 h(-1) with HDT. Muscular endurance (total work; maximal flexion-extension of the non-dominant knee at 180 degrees.s(-1) for 30 s) was not different between AC and the WI or HDT treatments. Shoulder-, knee-, and ankle-joint strength was unchanged except for three knee-joint peak torques: AC torque (120 degrees.s(-1), 285 +/- 20 Nm) decreased to 268 +/- 21 Nm (delta = -6%, p < 0.05) with WI; and AC torques (180 degrees.s(-1), 260 +/- 19 Nm) decreased to 236 +/- 15 Nm (delta = -9%, p < 0.01) with HDT, and to 235 +/- 19 Nm (delta = -10%, p < 0.01) with WI. CONCLUSION: Thus, the total body hypohydration threshold level for shoulder- and ankle-joint strength and endurance decrements is more than 2% body weight (water) loss, while significant reduction in knee-joint muscular strength-endurance occurred only at moderate (120 degrees.s(-1) and lighter (180 degrees.s(-1)) loads with body weight loss of 1.4-2.0% following WI or HDT, respectively. These weight (water) losses and knee-joint strength decrements are somewhat less than the mean weight loss of 2.6% and knee-joint strength decrements of 6-20% of American astronauts after

  20. Color View of a 'Rat' Hole Trail Inside 'Endurance'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This view from the Mars Exploration Rover Opportunity's panoramic camera is an approximately true color rendering of the first seven holes that the rover's rock abrasion tool dug on the inner slope of 'Endurance Crater.' The rover was about 12 meters (about 39 feet) down into the crater when it acquired the images combined into this mosaic. The view is looking back toward the rim of the crater, with the rover's tracks visible. The tailings around the holes drilled by the rock abrasion tool, or 'Rat,' show evidence for fine-grained red hematite similar to what was observed months earlier in 'Eagle Crater' outcrop holes.

    Starting from the uppermost pictured (closest to the crater rim) to the lowest, the rock abrasion tool hole targets are called 'Tennessee,' 'Cobblehill,' 'Virginia,' 'London,' 'Grindstone,' 'Kettlestone,' and 'Drammensfjorden.' Opportunity drilled these holes on sols 138 (June 13, 2004), 143 (June 18), 145 (June 20), 148 (June 23), 151 (June 26), 153 (June 28) and 161 (July 7), respectively. Each hole is 4.5 centimeters (1.8 inches) in diameter.

    This image was generated using the panoramic camera's 750-, 530-, and 430-nanometer filters. It was taken on sol 173 (July 19).

  1. Probabilistic seismic loss estimation via endurance time method

    NASA Astrophysics Data System (ADS)

    Tafakori, Ehsan; Pourzeynali, Saeid; Estekanchi, Homayoon E.

    2017-01-01

    Probabilistic Seismic Loss Estimation is a methodology used as a quantitative and explicit expression of the performance of buildings using terms that address the interests of both owners and insurance companies. Applying the ATC 58 approach for seismic loss assessment of buildings requires using Incremental Dynamic Analysis (IDA), which needs hundreds of time-consuming analyses, which in turn hinders its wide application. The Endurance Time Method (ETM) is proposed herein as part of a demand propagation prediction procedure and is shown to be an economical alternative to IDA. Various scenarios were considered to achieve this purpose and their appropriateness has been evaluated using statistical methods. The most precise and efficient scenario was validated through comparison against IDA driven response predictions of 34 code conforming benchmark structures and was proven to be sufficiently precise while offering a great deal of efficiency. The loss values were estimated by replacing IDA with the proposed ETM-based procedure in the ATC 58 procedure and it was found that these values suffer from varying inaccuracies, which were attributed to the discretized nature of damage and loss prediction functions provided by ATC 58.

  2. Improvement of Endurance of DMD Animal Model Using Natural Polyphenols

    PubMed Central

    Sitzia, Clementina; Farini, Andrea; Fortunato, Francesco; Razini, Paola; Erratico, Silvia; Tavelli, Alessandro; Fabrizi, Francesco; Belicchi, Marzia; Torrente, Yvan

    2015-01-01

    Duchenne muscular dystrophy (DMD), the most common form of muscular dystrophy, is characterized by muscular wasting caused by dystrophin deficiency that ultimately ends in force reduction and premature death. In addition to primary genetic defect, several mechanisms contribute to DMD pathogenesis. Recently, antioxidant supplementation was shown to be effective in the treatment of multiple diseases including muscular dystrophy. Different mechanisms were hypothesized such as reduced hydroxyl radicals, nuclear factor-κB deactivation, and NO protection from inactivation. Following these promising evidences, we investigated the effect of the administration of a mix of dietary natural polyphenols (ProAbe) on dystrophic mdx mice in terms of muscular architecture and functionality. We observed a reduction of muscle fibrosis deposition and myofiber necrosis together with an amelioration of vascularization. More importantly, the recovery of the morphological features of dystrophic muscle leads to an improvement of the endurance of treated dystrophic mice. Our data confirmed that ProAbe-based diet may represent a strategy to coadjuvate the treatment of DMD. PMID:25861640

  3. "Out of sight": Sexuality and women with enduring mental illness.

    PubMed

    Davison, Joanna; Huntington, Annette

    2010-08-01

    Sexuality is a complex and fundamental aspect of a person's health and mental well-being, yet mental health professionals generally seem reluctant to discuss sexuality related issues and few research studies have specifically explored the sexuality of women with enduring mental illness. The aim of this qualitative research was to gain a deeper understanding about the sexuality experiences of this group of women. Eight women were interviewed individually, and then together as a focus group. Working from a feminist theoretical perspective, the interview transcripts were analysed thematically. All the women considered sexuality an essential component of their identity. However, powerful interlocking systems controlled and influenced how the women expressed their sexuality, often marginalizing, and positioning them as 'Other', and rendering their sexuality hidden and unseen. The experiences of this group of women highlight the need for mental health professionals to recognize sexuality as an important aspect of a person's care and recovery, and to create a culture that is supportive of a person's sexuality and sexual expression. Incorporating sexuality related issues into clinical practice offers mental health professionals a significant opportunity to make a positive difference.

  4. Cooperative energy harvesting for long-endurance autonomous vehicle teams

    NASA Astrophysics Data System (ADS)

    Page, S. F.; Rogers, J. D.; May, K.; Myatt, D. R.; Hickman, D.; Smith, M. I.

    2010-04-01

    This paper considers the exploitation of energy harvesting technologies for teams of Autonomous Vehicles (AVs). Traditionally, the optimisation of information gathering tasks such as searching for and tracking new objects, and platform level power management, are only integrated at a mission-management level. In order to truly exploit new energy harvesting technologies which are emerging in both the commercial and military domains (for example the 'EATR' robot and next-generation solar panels), the sensor management and power management processes must be directly coupled. This paper presents a novel non-myopic sensor management framework which addresses this issue through the use of a predictive platform energy model. Energy harvesting opportunities are modelled using a dynamic spatial-temporal energy map and sensor and platform actions are optimised according to global team utility. The framework allows the assessment of a variety of different energy harvesting technologies and perceptive tasks. In this paper, two representative scenarios are used to parameterise the model with specific efficiency and energy abundance figures. Simulation results indicate that the integration of intelligent power management with traditional sensor management processes can significantly increase operational endurance and, in some cases, simultaneously improve surveillance or tracking performance. Furthermore, the framework is used to assess the potential impact of energy harvesting technologies at various efficiency levels. This provides important insight into the potential benefits that intelligent power management can offer in relation to improving system performance and reducing the dependency on fossil fuels and logistical support.

  5. A veterinary review of endurance riding as an international competitive sport.

    PubMed

    Nagy, Annamaria; Dyson, Sue J; Murray, Jane K

    2012-12-01

    The popularity of competitive endurance riding is growing worldwide and this has led to considerable changes in the discipline (e.g., fitter and faster horses and different types of injuries), which create challenges to all involved in the sport, including veterinarians. During endurance competitions, horses are closely monitored by veterinarians throughout the ride, with the aim of removing from the competition animals whose welfare appears to be endangered. This close monitoring provides veterinarians with an insight into problems during competi