Efficacy of strengthening or aerobic exercise on pain relief in people with knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: We performed a systematic review and meta-analysis of randomized controlled trials to investigate the differences in the efficacies between strengthening and aerobic exercises for pain relief in people with knee osteoarthritis. DATA SOURCES: This search was applied to Medline, Cochrane Central Register of Controlled Trials, the Physiotherapy Evidence Database, and the Cumulative Index to Nursing and Allied Health Literature. All literature published from each source's earliest date to March 2013 was included. REVIEW
METHODS: Trials comparing the effects of exercise intervention with those of either non-intervention or psycho-educational intervention were collected. Meta-analysis was performed for trials in which therapeutic exercise was carried out with more than three sessions per week up to eight weeks, for pain in people with knee osteoarthritis. All trials were categorised into three subgroups (non-weight-bearing strengthening exercise, weight-bearing strengthening exercise, and aerobic exercise). Subgroup analyses were also performed.
RESULTS: Data from eight studies were integrated. Overall effect of exercise was significant with a large effect size (standardised mean difference (SMD): -0.94; 95% confidence interval -1.31 to -0.57). Subgroup analyses showed a larger SMD for non-weight-bearing strengthening exercise (-1.42 [-2.09 to -0.75]) compared with weight-bearing strengthening exercise (-0.70 [-1.05 to -0.35]), and aerobic exercise (-0.45 [-0.77 to -0.13]).
CONCLUSION: Muscle strengthening exercises with or without weight-bearing and aerobic exercises are effective for pain relief in people with knee osteoarthritis. In particular, for pain relief by short-term exercise intervention, the most effective exercise among the three types is non-weight-bearing strengthening exercise.