TRAINING AND AGE EFFECTS ON SKELETAL MUSCLE INJURY AND REGENERATION AFTER ECCENTRIC EXERSICE.

肌肉损伤和/或损伤通常响应于强烈肌肉活动的偏心分量而发生。为研究大鼠跖肌变性和再生的形态学变化过程，用电刺激器和可调式足板刺激法诱发跖肌周期性离心收缩。本研究还观察了训练组和老年组大鼠下坡跑后趾长伸肌最大张力、直接/间接张力比值、突触延迟时间、llc型纤维和中央核纤维数目及损伤面积的变化过程，发现离心收缩试验后3-5天，出现明显的肌纤维损伤。近端肌纤维损伤多于中段和远端肌纤维。骨骼肌纤维损伤估计从组织化学分析的肌肉横截面类型IIb纤维主要受到影响。下坡跑后几天，强直性张力下降，并观察到一些肌肉损伤的证据。跑步训练组肌肉未观察到这些肌肉损伤，但观察到突触延迟轻微增加。然而，下坡跑后，肌肉损伤面积和恢复时间的显着增加与老年肌肉有关。总之，本研究表明，离心收缩后肌肉损伤的再生可能受到肌肉活动的影响，即，体育锻炼的时间和年龄。

Muscle damage and/or injury generally occurs in response to the eccentric component of intense muscular activity. To study the process of morphorgical changes associated with degeneration and regeneration in plantaris muscle of rat cyclic eccentric contraction was induced by using a stimulator and servomotor with an adjustable foot plate. And this study investigated the time couse of changes in maximum tention, relative ratio of direct/indirect tension, synaptic delay time, number of type llc fiber and central nuclei fiber, and damege area after down-hill running in extensor digitorum longus muscle of trained and old rats.Significant number of damaged muscle fibers were found 3-5 days after eccentric contraction test. Proximal part of the muscle included more damaged fibers than middle or diatall part. Skeletal muscle fiber injury was estimated from histochemical analysis of muscle cross-sections type lIb fibers were predominantly affected. A few days after downhill running the tetanic tension decreased and some muscle damaged evidences were observed in sedentary muscle. The running training muscle was not observed these muscle damages, but a slight increase in sinaptic delay was observed. However, significant increase in muscle damage area and recovery time for regeneration were associated with in old muscles after downhill running.In conclusion, this study showed that the muscle regenaration from injury after eccentric contraction may be influenced by muscle activities , i.e., physical training period and ages.