自発走トレーニングを伴う慢性過負荷が骨格筋の形態特性,筋線維タイプ構成比に及ぼす影響 [in Japanese] The effects of chronic overload with voluntary running on the morphological properties and myofiber type composition of rat plantaris muscles [in Japanese]
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The effects of chronic overload by synergistic ablation and voluntary running exercise on myofiber type composition, cross-sectional area and fatigue characteristics in rat plantaris muscles were examined in the present study. In plantaris muscles with overload and voluntary running exercise, a significant increases in the percentage of type I, IIa and He myofibers were induced compared that in muscles that were only overloaded. However, in the plantaris muscles with overload and voluntary running exercise, the percentage of type IIb myofibers was remarkably decreased compared to that of control muscles. When overload and voluntary running exercise were combined in the plantaris muscles, the cross-sectional areas of all type myofibers but not type IIb myofibers were significantly increased compared to that of control muscles; in particular the rate of hypertrophy of type IIa myofiber was strikingly larger than that in muscles that were only overloaded. The fatigue indices of plantaris muscles with chronic overload and voluntary running were dramatically higher than that of muscles that were only overloaded. Therefore, the present study demonstrated that running combined with chronic overload with phasic exercise is more effective for changing to a much slower muscle fiber type and acquiring a very rich muscle fatigue resistance by the drastic transition of myofiber type from "fast" to "slow" in addition to inducing significant muscle hypertrophy.
- Journal of exercise and sports physiology
Journal of exercise and sports physiology 15(1), 19-25, 2008-02