Article

Training induced changes in fatiguability of human skeletal muscle under voluntary and reflex conditions were investigated in eleven males. The training of the leg extensors 3 times a week for 16 weeks consisted of intensive muscle contractions (16-24 per one training session) with loads of 80-120% of one maximum repetition. The fatigue test for recording electromyographic and mechanical characteristics of the leg extensors was promoted before and after the training period by a maintained 50% isometric loading until exhaustion. The major findings of the present study demonstrated that fatiguability in voluntary muscle contraction was assessed after the strength training by a shorter endurance time (from 85.8 +/- 18.4 to 72.0 +/- 12.7 s, p< 0.05) and by a smaller increase in integrated EMG (IEMG)/force ratio (p< 0.001 and 0.01 for the pre- and posttests) as compared to the values of pretest. Similar decreases in mean power frequency and posttest (p< 0.001) fatigue loading. The increase in IEMG/force ratio and the decrease in MPF in the posttest were related (p< 0.05) to percentage of fast twitch (FT) fibres of the vastus lateralis muscle. An increase in EMG/force ratio of the reflex contraction due to fatigue loading was significantly (p< 0.05) smaller in the posttest in comparison to the respective increase in the pretest. The present findings suggest that the relative contributions of the reflex and voluntary responses during fatigue may be altered during the strength training period.

Langue : ANGLAIS

Identifiant basis : 1985002805