Exercise and mental health

What it is

Exercise here means planned activity such as walking or jogging, yoga, tai chi, strength training and aerobic sessions [1]. Most trials compare exercise with no treatment, a waiting list, usual care or an inactive activity [2].

What the research says

Across 63 meta-analyses of trials covering about 79,551 people, exercise reduced depression symptoms by a medium amount (standardised difference -0.61) [3]. A network analysis of 218 trials found walking or jogging, yoga and strength training gave the largest reductions, and the effect grew with intensity [1]. In a separate meta-analysis of 41 trials, supervised exercise gave the largest effects [4]. A Cochrane review of randomised trials in adults with depression found a pooled effect of -0.67 that fell to -0.46 in the seven trials with the strongest methods, and rated the certainty low [2]. Compared with talking therapy or antidepressants, exercise gave little to no difference in depression scores at the end of treatment, based on few trials [2].

For anxiety, a meta-analysis of 11 trials found a moderate reduction (standardised difference -0.66) [5], and the umbrella review found a smaller pooled effect (-0.47) [3]. In 27 trials of older adults with cancer, exercise reduced depression (-0.53) and anxiety (-0.39) compared with usual care [6].

Prospective studies that followed people over time also show a link. Across 49 prospective studies with about 267,000 people, the more physically active had 17% lower odds of developing depression [7]. In 13 prospective studies with about 76,000 people, higher activity was linked to 26% lower odds of developing anxiety [8].

Doses used in studies

Effects were larger at higher prescribed intensity in the network analysis [1]. The umbrella review found exercise of shorter duration and lower intensity was most strongly linked to lower anxiety, while group and supervised sessions were linked to greater reductions in depression [3]. The largest depression benefit appeared in people aged 18 to 30 and in postnatal women [3].

Safety and interactions

Adverse events were not common in the Cochrane trials; the ones reported included musculoskeletal injuries [2]. Yoga and strength training were the best tolerated options in the network analysis [1]. The umbrella review excluded people with chronic physical illness [3]. The reviews read for this topic do not report interactions with antidepressants or other medicines, so people taking treatment for depression or anxiety should talk to their doctor before changing their routine.

Caveats and open questions

Most trials were not blinded: randomisation was adequately concealed in only 22 studies, and only 23 used blinded outcome assessors [2]. Only one trial in the network analysis met low risk-of-bias criteria [1]. Long-term follow-up is rare, and the effect beyond the end of treatment is very uncertain [2]. The cohort studies show a link, not proof that exercise prevents depression or anxiety [7][8].