Abstract
[Purpose] The purpose is the effects of intermittent stretching exercise on disuse atrophy of the rat soleus muscle with respect to sites and muscle type. [Subjects] Twenty-one 8-week-old male Wistar rats were used. [Methods] The rats were divided into 3 groups: the CON group which received standard breeding, the HS group in which disuse atrophy of the soleus muscle was induced by hind-limb suspension, and the ST group which received intermittent stretching exercise during the hind-limb suspension period. At the end of the suspension period, the soleus muscle was excised and cut into proximal, middle, and distal samples which were stained with hematoxylin-eosin and ATPase. Subsequently, the cross-sectional area (CSA) was measured. [Results] CSAs of both type I and II fibers were significantly higher in the ST group than in the HS group, and the values of the middle region were significantly higher than those of the distal region. Also, the values of the distal region were significantly higher than those of the proximal region. [Conclusion] The results suggest that atrophy of both type I and II fibers of disused muscles is inhibited by stretching, and that there are differences in effect among the longitudinal sites of the rat soleus muscle.
