Biphasic effect of prior fatigue following eccentric-induced muscle dysfunction.

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doi:2013.22.1.23

Exerc Sci > Volume 22(1); 2013 > Article

Exercise Science 2013;22(1): 23-32. doi: https://doi.org/10.15857/ksep.2013.22.1.23

사전피로가 원심성 수축으로유발된 근 기능 장애에 미치는 이상성 효과

최승준¹, 전병환², 김승권³, 장창현³

¹경성대학교
²아산생명과학연구소
³선문대학교

Biphasic effect of prior fatigue following eccentric-induced muscle dysfunction.

Published online: December 14, 2015.

ABSTRACT

Purpose：Because muscle power output was completely recovered after 6 min with in vitro intact muscle experiment, we examined the interactive effects of prior fatigue and 6 min delayed eccentric contractions. Method：Solei were subjected to work loops in vitro at 35 °C. Pre-treatment, immediate post-treatment, and post-recovery cyclical power was assessed using 3 consecutive work loops that optimized pre-treatment power output (5Hz cycles；±5 % fiber length strain). The fatigue protocol consisted of 25 consecutive optimal cycles. Damage was induced by stimulating muscles during the lengthening phase of 10 consecutive low frequency (2 Hz), high amplitude (±25 % strain) cycles. Results：Muscles subjected to damaging contractions only (N=10) showed a significant reduction in power (37±1 %) and only partially recovered after 30min (81±0 %). Muscles that were fatigued and then immediately subjected to lengthening cycles (N=7) showed reduction in power that was significantly greater than all other treatments (69±2 %), but these muscles showed complete recovery of power (95±5 %). Muscles subjected to fatigued and then treated 6 min delayed lengthening cycles (N=7) showed a significant reduction in immediate power (40±4 %) that only partially recovered (79±7 %). Thus, 6min delayed eccentric treatment showed the identical result with eccentric only treatment.
Conclusion
：The effect of prior fatigue on muscle power output is depending upon the time between fatigue and eccentric contractions at whole intact muscle level. It suggest that the protective effect of prior fatigue appear to be due to an adaptation of above muscle level after eccentric muscle damage, such as central nerve system.

Key words: Eccentric contraction, Muscle fatigue, Cyclical power, Workloop