Reduction of Preserved Capacity for Skeletal Muscle with Aging and Effect of Exercise

已开发出可电子添加已知载荷的自行轮方案--1A。一项额外负荷的自愿运动导致纤维肥大，与平均跑步距离成正比。此外，在负重跑训练中，由于肌肉中所有类型的纤维都有纤维肥大，因此可以诱导所有运动单位类型的募集。方案2以10周龄、60周龄和120周龄大鼠为实验对象，研究了胫前肌和比目鱼肌肌纤维和运动神经元的数量和SDH活性随年龄的变化。60周龄快抽动肌纤维减少，120周龄慢抽动肌纤维和α运动神经元减少。此外，大的α运动神经元的SDH活性在120周龄时下降。因此，快、慢抽动肌的肌纤维退行性变过程不同。方案--40周龄大鼠自愿在增加负荷的跑轮上运动20周。与20周龄相比，60周龄比目鱼肌中雾状纤维较少，胫前肌中FG纤维较少。60周龄时胫前肌FOG和FG纤维横截面积小于20周龄。运动可预防胫前肌中雾纤维的萎缩。这些发现表明，运动可以通过恢复降低的代谢能力和抑制神经肌肉接头的退化来防止雾纤维的萎缩。

Program-1A voluntary running wheel in which a known load can be added electronically was developed. A voluntary exercise with an additional load resulted in fiber hypertrophy which was proportional to the average running distance. In addition, a recruitment of all motor unit type was induced during loaded-running exercise since fiber hypertrophy was observed in all fiber types in the muscle.Program-2The age-related changes in the number and SDH activity of muscle fibers and motoneurons of the tibialis anterior and soleus were studied using 1 0-, 60-, and 120-week-old rats. The number of fast-twitch muscle fibers was decreased at 60 weeks of age, while the number of slow-twitch muscle fibers and alpha motoneurons was decreased at 1 20 weeks of age. In addition, SDH activity of large alpha motoneurons was decreased at 1 20 weeks of age. Therefore, the degenerative process of muscle fibers differs between the fast- and slow-twitch muscles.Program-3Forty-week-old rats exercised voluntarily in running wheels with increasing loads for 20 weeks. There were fewer FOG fibers in the soleus muscle, and fewer FG fibers in the tibialis anterior muscle at 60 weeks than at 20 weeks of age. The cross-sectional area of FOG and FG fibers in the tibialis anterior muscle was lower at 60 weeks than at 20 weeks of age. Exercise prevented atrophy of FOG fibers in the tibialis anterior muscle. These findings suggest that exercise can prevent the atrophy of FOG fibers by restoring their decreased metabolic capacity, and by inhibiting the degeneration of neuromuscular junctions.