The motor control and recruitment of skeletal muscle during eccentric ecercise

我们研究了下坡跑过程中大鼠比目鱼肌(SOL)、指长伸肌(EDL)、指浅屈肌(FDS)和指伸肌(ED)梭内和梭外亚型的募集模式。另设安静对照组和运动组，每组6只。设安静对照组和运动组，每组6只，每只大鼠接受为期4周的训练(每周训练5天)。在实验当天，只有运动组大鼠进行下坡跑，即在运动带上以40m/min的速度进行4min的力竭跑，并沿6°坡度下坡。用高碘酸席夫S染色对肌球蛋白A天冬氨酸氨基转移酶染色鉴定的各亚型纤维半连续切片的糖原含量进行光镜观察。与对照组相比，四种骨骼肌梭外各亚型运动后糖原含量均显著降低。用于SOL和EDL…的梭外亚型SOL中IIA型(中间型)糖原降幅大于I型(慢型)，EDL中IIA值大于IIB型(快型)。但在前肢，ED的IIB型糖原降幅最大，ED的3种梭外纤维的降幅不明显。对于梭内肌纤维，运动后四种骨骼肌梭内各亚型的糖原含量均显著下降。在SOL和EDL肌梭中，bag2(中间型)的糖原降幅大于bag1(慢型)和bag1(快型)。在ED中，bag2的糖原减少也大于链状减少，但FDS的梭内纤维类型间无明显减少。结果提示，在下坡训练中，梭内亚型的募集模式与梭外亚型的募集模式不是直接相关的，可能不像梭外亚型那样依赖于大小原则。较少

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