Power output and fatigue of human muscle in maximal cycling exercise

We studied maximal torque-velocity relationships and fatigue during short-term maximal exercise on a constant velocity cycle ergometer in 13 healthy male subjects. Maximum torque showed an inverse linear relationship to crank velocity between 60 and 160 rpm, and a direct relationship to thigh muscle volume measured by computerized tomography. Peak torque per liter thigh muscle volume (PT, N X ml-1) was related to crank velocity (CV, rpm) in the following equation: PT = 61.7 - 0.234 CV (r = 0.99). Peak power output was a parabolic function of crank velocity in individual subjects, but maximal power output was achieved at varying crank velocities in different subjects. Fiber type distribution was measured in the two subjects showing the greatest differences and demonstrated that a high proportion of type II fibers may be one factor associated with a high crank velocity for maximal power output. The decline in average power during 30 s of maximal effort was least at 60 rpm (23.7 +/- 4.6% of initial maximal power) and greatest at 140 rpm (58.7 +/- 6.5%). At 60 rpm the decline in power over 30 s was inversely related to maximal oxygen uptake (ml X min-1 X kg-1) (r = 0.69). Total work performed and plasma lactate concentration 3 min after completion of 30-s maximum effort were similar for each crank velocity.

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A constant-load ergometer for measuring peak power output and fatigue

Journal of Applied Physiology ◽

10.1152/jappl.1988.65.5.2343 ◽

1988 ◽

Vol 65 (5) ◽

pp. 2343-2348 ◽

Cited By ~ 18

Author(s):

J. H. Williams ◽

W. S. Barnes ◽

J. F. Signorile

Keyword(s):

Power Output ◽

Peak Power ◽

Intraclass Correlation ◽

Average Power ◽

Load Cycle ◽

Constant Load ◽

Load Cell ◽

Peak Power Output ◽

Maximal Power Output ◽

Power Curves

A constant-load cycle ergometer was constructed that allows maximal power output to be measured for each one-half pedal revolution during brief, high-intensity exercise. To determine frictional force, an electronic load cell was attached to the resistance strap and the ergometer frame. Dead weights were attached to the strap's free end. Flywheel velocity was recorded by means of a magnetic switch and two magnets placed on the pedal sprocket. Pedaling resulted in magnetically activated switch closures, which produced two electronic pulses per pedal revolution. Pulses and load cell output were recorded (512 Hz), digitized, and stored on disk via microcomputer. Power output was later computed for each pair of adjacent pulses, representing average power per one-half pedal revolution. Power curves generated for each subject were analyzed for peak power output (the highest one-half pedal revolution average), time to peak power, power fatigue rate and index, average power, and total work. Thirty-eight males performed two 15-s tests separated by 15 min (n = 16) or 48 h (n = 22). Peak power output ranged from 846.0 to 1,289.1 W. Intraclass correlation analysis revealed high test-retest reliability for all parameters recorded on the same or different days (R = 0.91-0.97). No significant differences (P greater than 0.05) were noted between parameter means of the first and second tests. These results indicate that the ergometer described provides a means for conveniently and reliably assessing short-term power output and fatigue.

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Effect of a 25 ingredient sport drink on exercise performance and muscle oxygen extraction: a randomized controlled cross-over trial

Current Issues in Sport Science (CISS) ◽

10.15203/ciss_2017.008 ◽

2017 ◽

Author(s):

Hannes Gatterer ◽

Marc Philippe ◽

Hanno Fröhlich ◽

Stefan Bachler ◽

Florian Mosbach ◽

...

Keyword(s):

Exercise Performance ◽

Power Output ◽

Lactate Concentration ◽

Oxygenation Index ◽

Oxygen Extraction ◽

Sport Drink ◽

Maximal Power ◽

Maximal Power Output ◽

Muscle Oxygen ◽

Leg Strength

Many sport drinks contain a mixture of potential ergogenic substances. Recently, a new sport drink with 25 different ingredients was introduced to the market. Various athletes reported beneficial performance effects from the supplement, though without scientific evidence. The aim of this study was to investigate the effects of the sport drink on exercise performance. Nine sport students performed 3 test sessions including a cycle exercise tests to exhaustion, a leg strength test and a jump test. Each session was separated by 1 week. The first session was performed as a familiarization trial. In a random order, half of the participants performed the second session after consumption of the multi ingredient sport drink (MISD intake of 40g, 24 and 1h before each test) and half after placebo ingestion (same amount). During test session 3 the conditions were reversed (cross-over setting). Near infrared spectroscopy analyses were performed on the vastus lateralis during the MISD and placebo cycling test. The sport drink compared to placebo, improved maximal power output (7 watts, 95% CI 1.1-13.4), increased maximal lactate concentration (2.5 mmol/l, 95% CI 1.6-3.4), and power output at the individual threshold (Dmax) (6.1 watts, 95% CI 1.9-10.3). Power output at the 4 mmol/l threshold was reduced (9.0 watts, 95% CI -17.4 to -0.6) during the MISD trial. Additionally, the sport drink led to a steeper tissue oxygenation index decrease (TOI, slope: -0.0182±0.0084 vs. -0.0256±0.0073, p<0.005) during the test. Leg strength and jump ability was not affected by the supplement. The sport drink slightly increased power output during an incremental exercise test. Due to the broad range of substances in the supplement and their different effects, the factors involved in the performance enhancement are speculative. Data show that factors other than muscle oxygen extraction (represented by TOI) are involved in the improved maximal power output.

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Skeletal muscle structural and energetic characteristics in subjects with sickle cell trait, α-thalassemia, or dual hemoglobinopathy

Journal of Applied Physiology ◽

10.1152/japplphysiol.00349.2010 ◽

2010 ◽

Vol 109 (3) ◽

pp. 728-734 ◽

Cited By ~ 9

Author(s):

Lucile Vincent ◽

Léonard Féasson ◽

Samuel Oyono-Enguéllé ◽

Viviane Banimbek ◽

Géraldine Monchanin ◽

...

Keyword(s):

Skeletal Muscle ◽

Sickle Cell ◽

Power Output ◽

Citrate Synthase ◽

Sickle Cell Trait ◽

Fiber Type ◽

Time To Exhaustion ◽

Fiber Types ◽

Maximal Power ◽

Maximal Power Output

Previous studies have shown that subjects with sickle cell trait (SCT), α-thalassemia (α-t), and the dual hemoglobinopathy (SCT/α-t) manifest subtle, albeit significant, differences during exercise. To better understand such differences, we assessed skeletal muscle histomorphological and energetic characteristics in 10 control HbAA subjects (C), 5 subjects with α-t (α-t), 6 SCT carriers (SCT) and 9 SCT carriers with α-t (SCT/α-t). Subjects underwent a muscle biopsy and also performed an incremental maximal exercise and a time to exhaustion test. There were no observable differences in daily energy expenditure, maximal power output (Pmax), or time to exhaustion at 110% Pmax ( Tex) among the groups. Blood lactate concentrations measured at the end of the Tex, muscle fiber type distribution, and mean phosphofructokinase (PFK), lactate dehydrogenase (LDH), β-hydroxyacyl-CoA-dehydrogenase (HAD), and citrate synthase (CS) activities were all similar among the four groups. However, SCT was associated with a lower cytochrome- c oxidase (COx) activity in type IIa fibers ( P < 0.05), and similar trends were observed in fiber types I and IIx. Trends toward lower creatine kinase (CK) activity ( P = 0.0702) and higher surface area of type IIx fibers were observed in SCT ( P = 0.0925). In summary, these findings support most of the previous observations in SCT, such as 1) similar maximal power output and associated maximal oxygen consumption (V̇o2max) values and 2) lower exercise performances during prolonged submaximal exercise. Furthermore, performances during short supramaximal exercise were not different in SCT. Finally, the dual hemoglobinopathy condition does not seem to affect muscle characteristics.

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A Comparison of Isokinetic Knee Strength and Power Output Ratios Between Female Basketball and Volleyball Players

Human Movement ◽

10.1515/humo-2017-0022 ◽

2017 ◽

Vol 18 (3) ◽

Author(s):

Jarosław Kabaciński ◽

Michał Murawa ◽

Anna Fryzowicz ◽

Lechosław Bogdan Dworak

Keyword(s):

Power Output ◽

Peak Torque ◽

Quadriceps Muscle ◽

Maximal Power ◽

Basketball Players ◽

Maximal Power Output ◽

Squat Jump ◽

Knee Strength ◽

Counter Movement Jump ◽

Volleyball Players

AbstractPurpose. Tests such as the counter movement jump (CMJ) and squat jump (SJ) allow for determining the ratio of maximal power output generated during SJ to CMJ (S/C). The isokinetic peak torque ratio of the hamstrings contracting eccentrically to the quadriceps contracting concentrically (H/Q) is defined as functional H/Q. The purpose of this study was to compare the S/C and functional H/Q between female basketball and volleyball players. Methods. The total of 14 female basketball players (age, 19.8 ± 1.4 years) and 12 female volleyball players (age, 22.3 ± 4.2 years) participated in the study. A piezoelectric force platform was used for the CMJ and SJ. Moreover, isokinetic tests of the hamstrings and quadriceps muscle torque during eccentric and concentric contraction were performed. Results. The results of the S/C and functional H/Q at 90 deg · s

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Aerobic efficiency is associated with the improvement in maximal power output during acute hyperoxia

Physiological Reports ◽

10.14814/phy2.13119 ◽

2017 ◽

Vol 5 (2) ◽

pp. e13119 ◽

Cited By ~ 5

Author(s):

Tom A. Manselin ◽

Olof Södergård ◽

Filip J. Larsen ◽

Peter Lindholm

Keyword(s):

Power Output ◽

Maximal Power ◽

Maximal Power Output

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Effect of inspired O2 concentration on leg lactate release during incremental exercise

Journal of Applied Physiology ◽

10.1152/jappl.1996.81.1.246 ◽

1996 ◽

Vol 81 (1) ◽

pp. 246-251 ◽

Cited By ~ 24

Author(s):

D. R. Knight ◽

D. C. Poole ◽

M. C. Hogan ◽

D. E. Bebout ◽

P. D. Wagner

Keyword(s):

Blood Lactate ◽

Power Output ◽

Incremental Exercise ◽

Venous Blood Flow ◽

Maximal Power ◽

Maximal Power Output ◽

Lactate Accumulation ◽

Lactate Release ◽

O2 Concentration ◽

Blood Lactate Accumulation

The normal rate of blood lactate accumulation during exercise is increased by hypoxia and decreased by hyperoxia. It is not known whether these changes are primarily determined by the lactate release in locomotory muscles or other tissues. Eleven men performed cycle exercise at 20, 35, 50, 92, and 100% of maximal power output while breathing 12, 21, and 100% O2. Leg lactate release was calculated at each stage of exercise as the product of femoral venous blood flow (thermodilution method) and femoral arteriovenous difference in blood lactate concentrations. Regression analysis showed that leg lactate release accounted for 90% of the variability in mean arterial lactate concentration at 20-92% maximal power output. This relationship was described by a regression line with a slope of 0.28 +/- 0.02 min/l and a y-intercept of 1.06 +/- 0.38 mmol/l (r2 = 0.90). There was no effect of inspired O2 concentration on this relationship (P > 0.05). We conclude that during continuous incremental exercise to fatigue the effect of inspired O2 concentration on blood lactate accumulation is principally determined by the rate of net lactate release in blood vessels of the locomotory muscles.

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Physiological Factors That Allow for the Attainment of “Maximal Power Output” and “Entire Match Wrestling Power Output”

Physiology and Nutrition for Amateur Wrestling ◽

10.1201/9780429354779-11 ◽

2020 ◽

pp. 49-51

Author(s):

Charles Paul Lambert

Keyword(s):

Power Output ◽

Maximal Power ◽

Maximal Power Output ◽

Physiological Factors

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Maximal power output of a stochastic thermodynamic engine

Automatica ◽

10.1016/j.automatica.2020.109366 ◽

2021 ◽

Vol 123 ◽

pp. 109366

Author(s):

Rui Fu ◽

Amirhossein Taghvaei ◽

Yongxin Chen ◽

Tryphon T. Georgiou

Keyword(s):

Power Output ◽

Maximal Power ◽

Maximal Power Output

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Anaerobic energy provision does not limit Wingate exercise performance in endurance-trained cyclists

Journal of Applied Physiology ◽

10.1152/japplphysiol.00128.2002 ◽

2003 ◽

Vol 94 (2) ◽

pp. 668-676 ◽

Cited By ~ 114

Author(s):

J. A. L. Calbet ◽

J. A. De Paz ◽

N. Garatachea ◽

S. Cabeza de Vaca ◽

J. Chavarren

Keyword(s):

Exercise Performance ◽

Power Output ◽

Acute Hypoxia ◽

Lactate Concentration ◽

Oxygen Deficit ◽

Peak Power Output ◽

Fatigue Index ◽

Mean Power ◽

Anaerobic Energy ◽

Mean Power Output

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 O2 fraction = 0.10). Oxygen deficit was estimated from submaximal cycling economy tests by use of a nonlinear model. E cyclists showed higher maximal O2 uptake than S (72 ± 1 and 62 ± 2 ml · kg−1 · 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 O2 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.

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