The motor control and recruitment of skeletal muscle during eccentric ecercise

点击翻译按钮获取中文摘要

We investigated the recruitment patterns of intrafusal and extrafusal subtypes in the rat soleus (SOL), extensor digitorum longus (EDL), flexor digitorum superficial (FDS) and extensor digitorum (ED) muscles during downhill running. A rest control and an exercise group of six rats each were prepared. A rest control and an exercise group of six rats each were prepared and each rat was subjected to training (5 days per week) for four weeks. Only the rat of the exercise group carried out a downhill running, an exhaustive 4-min run on a motordriven belt with a speed of 40m/min and down a 6°incline, on the experiment day. Periodic acid Schiff' s stain was used to estimate optically the glycogen content of the semi-serial sections of each fiber subtype which were identified by myosin A TPase staining. Compared with the control group, the glycogen contents after exercise decreased significantly in all extrafusal subtypes of four kind of skeletal muscles. For extrafusal subtypes of SOL and EDL … More which was hind leg, the glycogen decrease of type IIA (intermediate type) in SOL were larger than type I (slow type), and the value of IIA in EDL was larger than type IIB (fast type). In the fore leg, however, in ED the glycogen decrease of type IIB was largest among the extrafufsal subtypes, and in ED non-significant decreased was found in the three types of extrafusal fibers. For intrafusal muscle fibers, the glycogen contents after exercise decreased significantly in all intrafusal subtypes of four kind of skeletal muscles. In SOL and EDL muscle spindles, the glycogen decrease of bag2 (intermediate type) was larger than type bag1 (slow type) either chain (fast type). In ED, the glycogen decrease of bag2 was also larger than chain, but there was non-singnificant decreased among the types of intrafusal fibers in FDS.The results suggest that during downhill running as an eccentric exercise model, the recruitment patters of intrafusal subtypes are not straight forward relation to those of extrafusal subtypes and might be not depend on size principle like a extrasusal subtypes. Less