Influence of Heat Treatment on Muscle Recovery after Skeletal Muscle Injury in Rats: Histological and Immunohistochemical Studies

BACKGROUND: Muscle injuries represent a great part of athletic injuries. The repairing of skeletal muscle after injury is highly influenced by its regenerative response that may be affected by thermotherapy. AIM: This research examined the consequence of heat therapy on muscle recovery after skeletal muscle injury in rats. MATERIALS AND METHODS: Forty-five male adult albino rats were classified into three groups: control, cardiotoxin-injected without heat (nonheating group), and cardiotoxin-injected with heat (heating group). Muscle injury was caused by the injection of cardiotoxin intramuscularly into the tibialis anterior muscles. Heating treatment (40°C for 20 min) was started immediately after the injury. Subsequent observations were performed at day 1, 3, and 7 after injury, including histological imaging and vimentin immunostaining expression. RESULTS: In the heating group, the regenerating myotubes, having two or more central nuclei, first looked at 3 days after muscle injury, while in the nonheating group, the regenerating fibers were first observed at 7 days after muscle injury. Immunohistochemically, the vimentin reactions were absent in control muscle fibers but were identified in regenerating muscle fiber of the heating group earlier than in the nonheating group. CONCLUSION: Starting of heat treatment immediately after muscle injury promoted the regeneration of muscle fibers.