Effect of training on central factors in fatigue following two- and one-leg static exercise in man.
Leg strength and fatigue developed during 150 repeated two- and one-leg isometric maximal voluntary contractions were determined before and after a 5-week one- (n = 6) or two- (n = 7) leg training programme including a control group of five subjects. Two- and one-leg training increased two- and one-leg strength by 59 (range 8-107) and 36% (-1-69) respectively (P less than 0.01) with no significant difference between the two groups. Two-leg training decreased (P less than 0.05) fatigue only during two-leg maximal voluntary contractions (from 20 [11-26] to 13% [6-27]); and one-leg training fatigue only during one-leg maximal voluntary contractions (from 20 [15-23] to 11% [9-24]) despite the fact that both legs were trained. Surface electromyographic activity decreased during both repeated two- and one-leg maximal voluntary contractions (P less than 0.01) but a reduction in electromyographic decay was seen (P less than 0.05) during two-leg maximal voluntary contractions after two-leg training. Training increased fast-twitch b fibre size (P less than 0.01), and glycogen depletion was seen in fast-twitch (a and b) fibres, but the relative fast-twitch b area did not increase significantly. No training effects were seen in the control group. The results show that an approximately 47% increase in muscle strength may take place without a significant change in the relative percentage of muscle fibre types or in the average muscle fibre size. Furthermore, the specificity of the training response to fatigue developed during repeated two- and one-leg maximal voluntary contractions suggests a change in the nervous influence on the motor units.
Rube
N
N
Danish Anti-Polio Society, Hellerup.
Secher
N H
NH
D000328:Adult; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology*; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009132:Muscles / Q000378:metabolism / Q000502:physiology; D011187:Posture / Q000502:physiology*
D006003:Glycogen