筋疲労回復過程の筋電図学的分析

元データ 1987-03-15

概要

The purpose of the present study was to investigate the muscular activities during fatigue and recovery by means of electromyogram (EMG). The EMG power spectrum and the integrated EMG (IEMG) of the surface EMG recorded over the muscle of biceps brachii were examined in five male subjects during fatiguing isometric contraction followed by intermittent brief isometric contractions. The mean power frequency (MPF) was calculated and used as a single estimate of the EMG power spectrum. Contraction was maintained during 25 and 50% of their maximum voluntary contraction (MVC). The results obtained from the present study were ; 1) In unfatigued condition at 50% of MVC load the MPF showed higher values than at 25% of MVC load. 2) During fatiguing contraction at 50% of MVC load the MPF showed exponential decrement with time, returning to basal level within 5 min during recovery. 3) At 25% of MVC load the MPF varied little during fatiguing contraction and recovery. 4) During fatiguing contraction at 50% of MVC load the IEMG showed linear increment with time, while at recovery it showed little decrement within 15 min. 5) During fatiguing contraction at 25% of MVC load the IEMG showed exponential increment with time, and during recovery it showed rapid decrement within 1 min. It is clarified that the power spectrum and the IEMG during fatiguing contraction and recovery are effected by muscular force level. Recruitment order of motor unit is altered by muscular force level so that the threshold force of motor unit is different between FT and ST fiber. It is suggested that during 25% of MVC load ST fiber that has low conduction velocity of muscle fiber action potential, little lactate production and rapid lactate removal is recruited prior. During 50% of MVC load FT fiber that has high conduction velocity of muscle fiber action potential, much lactate production and slow lactate removal is recruited prior. So these two factors may effect on the power spectrum and IEMG.

著者

山本 高司 中京大学大学院体育学研究科運動生理学研究室

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