Influence of an aquatic resistance progressive exercise and low-level laser therapy on musculoskeletal atrophy: an experimental model of knee osteoarthritis.

The aim of this study was to evaluate the effectiveness of an aquatic progressive resistance exercise (APRE) and PBM (associated or not) on morphology of skeletal muscle and biochemical markers using an experimental model of knee osteoarthritis (OA). Fifty male Wistar rats were randomly distributed into 5 groups: control group (CG); OA control (OAC); OA submitted to APRE (OAE); OA submitted to PBM (OAL); OA submitted to APRE and PBM (OAEL). Trained rats performed a water-jumping program carrying a load equivalent to 50-80% of their body mass strapped to their chest. Laser irradiation (808 nm) was performed on 2 points of the knee joint. Treatments (3 days a week, for 8 weeks) started 4 weeks after the OA induction. The results showed that all OA groups presented a significantly increase in the muscle cross-section area (CSA) and a decrease in muscle fiber density compared to CG. Moreover, both trained groups presented a reduced expression of atrogin and an intense myoD immunoexpression in the laser exercised animals. The results demonstrate that APRE was effective in reducing muscle atrophy markers and its association with PBM could be effective in modulating molecules involved in muscle recovery in knee OA.