The effects of exercise on depression have been a source of contentious debate. Meta-analyses have demonstrated a range of effect sizes. Both inclusion criteria and heterogeneity may influence the effect sizes reported. The extent and influence of publication bias is also unknown. Randomized controlled trials (RCTs) were identified from a recent Cochrane review and searches of major electronic databases from 01/2013 to 08/2015. We included RCTs of exercise interventions in people with depression (including those with a diagnosis of major depressive disorder (MDD) or ratings on depressive symptoms), comparing exercise versus control conditions. A random effects meta-analysis calculating the standardized mean difference (SMD, 95% confidence interval; CI), meta-regressions, trim and fill and fail-safe n analyses were conducted. Twenty-five RCTs were included comparing exercise versus control comparison groups, including 9 examining participants with MDD. Overall, exercise had a large and significant effect on depression (SMD adjusted for publication bias = 1.11 (95% CI 0.79-1.43)) with a fail-safe number of 1057. Most adjusted analyses suggested publication bias led to an underestimated SMD. Larger effects were found for interventions in MDD, utilising aerobic exercise, at moderate and vigorous intensities, in a supervised and unsupervised format. In MDD, larger effects were found for moderate intensity, aerobic exercise, and interventions supervised by exercise professionals. Exercise has a large and significant antidepressant effect in people with depression (including MDD). Previous meta-analyses may have underestimated the benefits of exercise due to publication bias. Our data strongly support the claim that exercise is an evidence-based treatment for depression.

Low levels of physical activity (PA) and sedentary behavior (SB) are independent risk factors for cardiovascular disease and premature mortality in people with major depressive disorder (MDD). Investigate levels of PA and SB and their predictors in people with MDD. Electronic databases were searched from inception till 04/2016 for articles measuring PA and SB with a self-report questionnaire (SRQ) or objective measure (e.g. accelerometer) in people with MDD. Random-effects meta-analyses and meta-regression analyses were conducted. Twenty-four eligible studies were identified including 2901 people with MDD (78.4% female, mean age=54 years; range: 21-77 years). People with MDD spent 126.0min (95%CI=91.9-160.1) per day engaging in all types of PA and spent 8.5hours (95%CI=7.51-9.62) during their waking day being sedentary. Compared to controls, people with MDD spent less time in total PA (SMD=-0.25, 95%CI=-0.03 to 0.15) and moderate to vigorous PA (SMD=-0.30, 95%CI=-0.40 to 0.21) and engaged in higher levels of SB (SMD=0.09, 95%CI=0.01-0.18). The proportion of people with MDD not meeting the recommended PA guidelines was 67.8% (n=13 studies), which was higher in studies relying on objective versus self-report measures (85.7% v 62.1%, p=0.04). People with MDD were more likely than controls to not meeting the recommended PA guidelines (OR = 1.50, 95%CI = 1.10–2.10). Heterogeneity was evident in most analyses. Adults with MDD engage in low levels of PA and high levels of SB. PA and SB are independent predictors of mortality, therefore, future lifestyle interventions targeting both the prevention of SB and adoption and maintenance of PA are warranted.