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

肌肉损伤和/或损伤通常发生于剧烈肌肉活动的偏心成分。采用刺激器和带可调节足板的伺服运动装置，研究大鼠足底肌退行性和再生的形态学变化过程。研究了训练大鼠和老年大鼠指长伸肌下坡跑后最大张力、直接/间接张力相对比、突触延迟时间、llc型纤维和中央核纤维数量、损伤面积的变化时间。离心收缩试验后3 ~ 5天，肌纤维明显受损。肌近端损伤纤维多于中端或腹侧损伤纤维。骨骼肌纤维损伤由肌肉横截面组织化学分析估计，类型lIb纤维主要受到影响。下坡跑步后数日，久坐肌的强直性张力下降，有一定的肌肉损伤迹象。跑步训练肌未观察到这些肌肉损伤，但观察到突触延迟略有增加。然而，在下坡跑步后，肌肉损伤面积和再生恢复时间的显著增加与老化肌肉有关。综上所述，本研究表明偏心收缩损伤后的肌肉再生可能受到肌肉活动的影响，即体能训练时间和年龄。

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.