Twenty-seven RCTs (1,596 participants) were included in the review. Fifteen studies (1,119 participants) assessed the effects of land-based aerobic activity, seven studies (288 participants) assessed the effects of water-based aerobic activity and five studies (189 participants) assessed muscle strengthening exercises. The proportion of participants in the studies that were reported to have dropped out during the study ranged from zero to 56%.
Physical function: Nine out of 12 studies found that land-based aerobic exercise significantly improved physical function when compared to control; in four studies the control group had no treatment, in two studies the control group received education and in three studies the control group underwent flexibility and stretching exercises.
Four out of five studies found that water-based aerobic exercise significantly improved physical function when compared to control; two studies used untreated controls, one study used a control group that had recreational activities other than swimming and one study compared water-based aerobic exercise with land-based aerobic exercise. All five studies of muscle strengthening exercises found a significant improvement in physical function compared to untreated controls or controls doing flexibility exercises.
Pain: Six out of 11 studies found a statistically significant reduction in spontaneous pain with land-based aerobic exercise compared to control and five studies found no evidence of a difference in pain levels. Five out of seven studies found a reduction in pain in water-based aerobic exercise when compared to either untreated controls (two participants) or land-based aerobic exercise (three participants). The other two studies found no evidence of a statistical difference between randomised groups.
Two out of five muscle strengthening exercises studies found that strengthening exercises was significantly more effective in reducing pain compared to no treatment or flexibility exercises; three of five studies found no evidence of a statistical difference between randomised groups.
Mental function: Three studies found a statistically significant reduction in symptoms of anxiety and depression with land-based aerobic exercise compared to either no treatment controls or controls doing stretching exercises. It was not reported how many studies measured depression or other aspects of mental function. One study found a statistically significant benefit in fatigue and cognitive function with land-based aerobic exercise compared to no treatment.
Five out of seven studies found a statistical improvement in mental function (depression, anxiety, quality of life and/or general mental health) with water-based aerobic exercise compared to control that included no treatment, games, land-based aerobic exercise or water-based aerobic exercise in a pool (compared to sea-based aerobic exercise). Two out of five muscle strengthening exercises studies found that these improved symptoms of depression.