Spatial patterns of atrophied muscle fibers during exercised recovery

The effect of run training during the recovery period on the spatial distributions of fiber type was examined in atrophic soleus muscle of adult rats following 28 days of hindlimb suspension. During recovery, clusters of damaged and type IIC fibers were observed, which were more pronounced in the exercised animals than in both exercised and nonexercised control groups. The results indicate that exercise during recovery following suspension-induced hindlimb muscle atrophy produces changes in the soleus fiber-type cross-sectional area, both absolute and relative. These changes were not seen in the sedentary recovery group or in control rats exposed to the same exercise regimen. The author concludes that this treatment, unlike neurogenic pathologies, does not cause any remodeling during recovery, in the sense of changed adjacency relations among fiber types.