Document Detail


Reproducible voluntary muscle performance during constant work rate dynamic leg exercise.
MedLine Citation:
PMID:  10727069     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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 four performance indices: MVC force of rested muscle (MVC(rest)) rate of MVC force fall, time to exhaustion, and percentage of MVC(rest) (%MVC(rest)) at exhaustion in 11 healthy women (22+/-1 yrs) during identical constant work rate 1-leg DKE (1 Hz) on 2 separate days at sea level (30 m). Means+/-SD for the two test days, and the correlations (r), standard estimate errors and coefficients of variation (CV%) between days were, respectively: a) MVC(rest)(N), 524+/-99 vs 517+/-111, 0.91, 43.0, 4.9%; b) MVC force fall (N x min(-1)), -10.77+/-9.3 vs -11.79+/-12.1, 0.94, 3.6, 26.5 %; c) Time to exhaustion (min), 22.6+/-12 vs 23.9+/-14, 0.98, 2.7, 7.5 %; and d) %MVC(rest) at exhaustion, 65+/-13 vs 62+/-14, 0.85, 7.8, 5.6%. There were no statistically significant mean differences between the two test days for any of the performance measures. To demonstrate the potential benefits of evaluating multiple effects of an experimental intervention, nine of the women were again tested within 24hr of arriving at 4,300 m altitude using the identical force, velocity, power output, and energy requirement during constant work rate dynamic leg exercise. Low variability of each performance index enhanced the ability to describe the effects of acute altitude exposure on voluntary muscle function.
Authors:
C S Fulco; P B Rock; S R Muza; E Lammi; A Cymerman; S F Lewis
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  International journal of sports medicine     Volume:  21     ISSN:  0172-4622     ISO Abbreviation:  Int J Sports Med     Publication Date:  2000 Feb 
Date Detail:
Created Date:  2000-04-21     Completed Date:  2000-04-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8008349     Medline TA:  Int J Sports Med     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  102-6     Citation Subset:  IM; S    
Affiliation:
U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760, USA. charles.fulco@na.amedd.army.mil
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MeSH Terms
Descriptor/Qualifier:
Adult
Altitude
Biomechanics
Exercise / physiology*
Female
Humans
Knee Joint / physiology
Leg / physiology
Muscle Fatigue / physiology*
Physical Endurance / physiology*
Reproducibility of Results
Weight-Bearing

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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