Effect of the Stretching Exercise on Passive Tension in Atrophy Muscle

Abstract

The aim of the present study was to examine the mechanical properties of skeletal muscle during stretching in atrophic muscle. The changes in mechanical properties (passive tension) during stimulation by ramp and hold stretching were studied in the rat soleus muscle with disuse atrophy. Muscular atrophy was induced by hindlimb suspension (HS) or by immobilization with plaster cast (CAST) for two weeks. During stretch condition, passive tensions of skeletal muscles were significantly reduced in HS and increased in CAST. The passive tension was significantly decreased after the continuous stretching exercise (10 minutes) in immobilized hindlimb. On the other hand, monitoring of the continuum for stretch-induced injury allows us to define the threshold of stretch injury. The skeletal muscle was stretched until failure in situ. The passive tension of skeletal muscle was significantly increased by stretching. A threshold for stretch-induced injury does exist.
These results indicate that following muscular atrophy, achieved through two weeks of hindlimb immobilization, the mechanical properties of the skeletal muscle are changed. We suggest that awareness of changes of muscular mechanical properties could provide a useful clue for advancing various therapeutic programs for physical therapy of patients with atrophic muscles.