Electromyographic manifestations of neuromuscular fatigue of different muscle groups during exercise and arterial occlusion / 体力科学

ABSTRACT

Neuromuscular fatigability of different muscle groups was studied under various physiological conditions in eight healthy male subjects by means of EMG fatigue curve analysis (E/F ratio defined as the rate of rise in IEMG/force as a function of time) which has been commonly used.<BR>Under the experimental conditions and assumptions described in the present investigation, the following conclusions could be justified on the basis of the experimental results.<BR>1. The E/F ratio for the biceps brachii muscle was significantly greater (p<0.0005) than that of the soleus muscle at 40% of MVC, suggesting that the biceps brachii with presumably greater %FT fibers were consistantly more fatigable than their own soleus muscle.<BR>2. The exponential growth of the E/F ratio as a function of either the maximal sustaining time (T<SUB>s</SUB>) or different fractions of MVC suggested a possible neurophysiological link between the fatigability of the biceps brachii muscle and their MU activities which might increase in an accelerated fashion.<BR>3. The evaluation of static work capacity (W<SUB>s</SUB>) described in the present study revealed that the differences in the critical force level and Ws during free circulation and arterial occlusion could be explained by the relative availability of muscle blood flow which might determine the rate of energy reconstitution.<BR>4. The EMG data taken during a constant torque output on an electrically braked bicycle ergometer indicated that some shift in the MU recruitment and/or MU firing frequency may occur during the application of arterial occlusion causing local muscle hypoxia.