Reproducible Muscle Performance During Constant Work Rate Dynamic Leg Exercise.
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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During constant intensity treadmill or cycle exercise, progressive muscle fatigue is not readily quantified and endurance time is poorly reproducible. However, integration of dynamic knee extension DKE exercise with serial measurement of maximal voluntary contraction MVC force of knee extensor muscles permits close tracking of leg fatigue. We studied reproducibility of 4 performance indices MVC force of rested muscle MVCrest, rate of MVC force fall, time to exhaustion, and percentage of MVCrest MVCrest at exhaustion in 11 healthy women 22 1 yr during identical constant work rate 1-leg DICE 1 Hz on 2 separate days. Means 1- SD, correlation r and standard estimate error S.E.E. between days were, respectively a. MVCrest N, 524 1-99 vs 517 1-111,0.91,43.0 b. MVC force fall N inin-1, -10.77 1-9.3 vs -11.79 1-12.1,0.94,3.6 c. Time to exhaustion min, 22.61- 12 vs 23.91- 14, 0.98, 2.7 and d. MVCrest at exhaustion, 65 1-13 vs 621- 14, 0.85, 7.8. There were no statistically significant differences between the two test days for any of the performance measures. Low variability of each index should enhance the ability to define the effects of a variety of interventions on voluntary muscle function during constant work rate dynamic leg exercise.
- Anatomy and Physiology
- Medicine and Medical Research