Authors: Sébastien Boyas Arnaud Guével
Publish Date: 2010/12/03
Volume: 111, Issue: 6, Pages: 1187-1196
Abstract
The purpose of endurance time T lim prediction is to determine the exertion time of a muscle contraction before it occurs T lim prediction would then allow the evaluation of muscle capacities limiting fatigue and deleterious effects associated with exhaustive exercises The present study aimed to analyze the influence of exercise intensity and joint angle on T lim prediction using changes in surface electromyographic sEMG signals recorded during the first moments of the exercise Fifteen male performed four knee extensions sustained until exhaustion that were different in exercise intensity 20 or 50 of maximal voluntary torqueMVT and in joint angle 40 or 70º 0° = full extension T lim prediction was explored using some parameters of the sEMG signals from rectus femoris vastus medialis and vastus lateralis muscles Changes in sEMG parameters root mean square mean power frequency and frequency banding 6–30 Hz were expressed using the slope of the linear regression and the area ratio index Results indicated that relationships between changes in sEMG signal and T lim 051 r 083 were greater for experimental conditions associated with higher exercise intensity 50 MVT and so to lower time duration Knee joint angle had little influence on T lim prediction results Results also showed higher T lim prediction considering spectral parameters and area ratio This could be in relation to differences in relative contribution of central and peripheral fatigue that seems to change according to the exercise intensity but also to the influence of psychological factors that increases with the duration of the task
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