Comparative Effects of Low-Intensity Pulsed Ultrasound and Low-Level Laser Therapy on Injured Skeletal Muscle

Abstract

Objective: the main purpose of this study was to compare the effects of low-intensity pulsed ultrasound (US) and low-level laser therapy (LLLT) on injured skeletal muscle after cryolesion by means of histopathological analysis and immunohistochemistry for cyclo-oxygenase-2 (COX-2). Background and Methods: Thirty-five male Wistar rats were randomly distributed into four groups: intact control group with uninjured and untreated animals; injured control group with muscle injury and no treatment; LLLT-treated group with muscle injury treated with 830-nm laser; and US-treated group with muscle injury treated with US. Treatments started 24 h postsurgery and were performed during six sessions. Results: LLLT-treated animals presented minor degenerative changes of muscle tissue. Exposure to US reduced tissue injuries induced by cryolesion, but less effectively than LLLT. A large number of COX-2 positive cells were found in untreated injured rats, whereas COX-2 immunoexpression was lower in both LLLT-and US-treated groups. Conclusion: This study revealed that both LLLT and US therapies have positive effects on muscle metabolism after an injury in rats, but LLLT seems to produce a better response.