A Cochrane review included 54 studies.
Exercise reduced pain (SMD -0.49, 95% CI -0.39 to -0.59) immediately after treatment (44 trials, 3537 participants). Pain was estimated at 44 points on a 0 to 100-point scale (0 indicated no pain) in the control group; exercise reduced pain by an equivalent of 12 points (95% CI 10 to 15 points). Exercise improved physical function (SMD -0.52, 95% CI -0.39 to -0.64) immediately after treatment (44 trials, 3913 participants). Physical function was estimated at 38 points on a 0 to 100-point scale (0 indicated no loss of physical function) in the control group; exercise improved physical function by an equivalent of 10 points (95% CI 8 to 13 points). Exercise improved quality of life (SMD 0.28, 95% CI 0.15 to 0.40) immediately after treatment (13 studies,1073 participants). Quality of life was estimated at 43 points on a 0 to 100-point scale (100 indicated best quality of life) in the control group; exercise improved quality of life by an equivalent of 4 points (95% CI 2 to 5 points).
Meta-analysis revealed a beneficial treatment effect with a standardized mean difference (SMD) of 0.40 (95% CI 0.30 to 0.50) for pain; and SMD 0.37 (95% CI 0.25 to 0.49) for physical function. There was marked variability across the included studies in participants recruited, symptom duration, exercise interventions assessed and important aspects of study methodology. The results were sensitive to the number of direct supervision occasions provided and various aspects of study methodology. While the pooled beneficial effects of exercise programs providing less than 12 direct supervision occasions or studies utilising more rigorous methodologies remained significant and clinically relevant, between study heterogeneity remained marked and the magnitude of the treatment effect of these studies would be considered small.