Exercise improves cardiorespiratory fitness in people with depression: A meta-analysis of randomized control trials.

Objective: Cardiorespiratory fitness (CRF) is an independent predictor of cardiovascular disease and all-cause mortality. CRF improves in response to exercise interventions, yet the effectiveness of such interventions to improve CRF among people with depression is unclear. We conducted a systematic review and meta-analysis to evaluate whether CRF improves in people with depression in exercise randomized control trials (RCTs).

Method: Three authors identified RCTs from a recent Cochrane review and conducted updated searches of major electronic databases. We included RCTs of exercise interventions in people with depression (including major depressive disorder (MDD) and above-threshold depressive symptoms) that reported CRF (defined as predicted maximal oxygen uptake (VO2max predicted) or peak oxygen uptake (VO2peak)) versus a control condition. A random effects meta-analysis was conducted.

Results: Seven unique RCTs including 8 aerobic exercise interventions for depression were eligible, including 293 people allocated to exercise (mean age=40.3 years, range=27.2-64.7 years and 35-100% female) and 205 allocated to control conditions. Across all studies exercise results in a significant increase in CRF (g=0.64, 95%CI=0.32-0.96, p<0.001) equating to a mean increase of 3.05 ml/kg/min. Results remained significant when restricted to MDD only (N=5, g=0.41, 95%CI=0.18-0.64, p<0.001) and in high quality studies (N=5, g=0.60, 95%CI=0.19-1.00, p=0.004).

Conclusions: People with depression can achieve clinically relevant improvements in CRF in response to exercise interventions. Targeting 'fitness' rather than 'fatness' may be another feasible intervention strategy in this population.