Eccentric exercise and stretching for plantar flexor muscles applied during 21 days after immobilization do not modify the non-contractile tissue

ABSTRACT The adaptations of the extracellular matrix, which is closely related to the maintenance of the integrity and performance of the musculoskeletal system, are not widely described in the literature after rehabilitation due to prolonged disuse. The aim of this study was to analyze the perimysial connective tissue area and the cross-sectional area of muscle fibers in soleus and plantaris muscles of immobilized female rats, later rehabilitated due to stretching and eccentric exercise protocols. The expression of the perimysial connective tissue of both studied muscles did not show significant differences after the procedure of immobilization and training. Eccentric training applied for 10 days was enough to recover the area of fibers for the plantaris muscle, while the recovery of the soleus muscle happened only after the 21-days protocol.