Musculoskeletal Atrophy in an Experimental Model of Knee Osteoarthritis The Effects of Exercise Training and Low-Level Laser Therapy

Objective The aim of this study was to evaluate the effects of an exercise training protocol and low-level laser therapy (and the association of both treatments) on musculoskeletal atrophy using an experimental model of knee osteoarthritis (OA). Design Fifty male Wistar rats were randomly divided into five groups: control group, knee OA control group, OA plus exercise training group, OA plus low-level laser therapy group, and OA plus exercise training associated with low-level laser therapy group. The exercise training and the laser irradiation started 4 wks after the surgery, 3 days per week for 8 wks. The exercise was performed at a speed of 16 m/min, 3 days per week, 50 mins per day, for 8 wks. Laser irradiation was applied at two points of the left knee joint (medial and lateral), for 24 sessions. Results The results showed that both trained groups (irradiated or not) presented a significant increase in the muscle cross-sectional area and a decrease in muscle fiber density compared with the knee OA control group. Moreover, both trained and laser-irradiated groups demonstrated decreased muscle-specific ring-finger protein 1 and atrogin-1 immunoexpression. Conclusions These results suggest that exercise training and low-level laser therapy were effective in preventing musculoskeletal alterations related to atrophy caused by the degenerative process induced by knee OA.