Resistance Exercise Training For Depressive Symptoms Compared To Active And Inactive Comparisons: A Meta-analysis

Available evidence supports the antidepressant effects of resistance exercise training (RET) compared to no-treatment comparison conditions. Although promising, the efficacy of RET to reduce depressive symptoms compared to potential active treatments remains unclear. PURPOSE: To estimate the population mean effect from randomized controlled trials (RCTs) of RET effects on depressive symptoms compared to both inactive and active comparisons, and explore potential sources of heterogeneity. METHODS: Peer-reviewed articles published before October 2021 were located using MEDLINE, PsycINFO, PubMed, and Web of Science. Randomized trials that compared RET to any other comparison group with validated measures of depressive symptoms at baseline, mid-intervention, and/or post-intervention, were included. Hedges’ d effect sizes were computed, and random effects models were used for all analyses. RESULTS: One-hundred and seven effects were derived from 64 RCTs. RET resulted in a small-to-moderate magnitude, heterogeneous improvement in depressive symptoms (Δ = 0.43, 95%CI: [0.33-0.53]; z = 8.53, p < 0.001; Q(106) = 323.79, p < 0.001). Effects of RET were larger compared to inactive comparisons (Δ = 0.59, [0.45-0.74]; z = 8.01, p < 0.001), and were small, but significant, compared to active comparisons (Δ = 0.19, [0.09-0.29]; z = 3.64, p < 0.001). Effects of RET were also larger among females (Δ = 0.50, [0.32-0.68]; z = 5.47, p < 0.001) than males (Δ = 0.26, [-0.02 to 0.54]; z = 1.80, p = 0.074), for RET frequencies of 2-4 d/wk (Δ = 0.41-0.90; all p < 0.001), and for intervention durations of ≤12 weeks (Δ = 0.50-0.55; all p < 0.001). When compared directly, there was no significant difference between the effects of RET and aerobic exercise training (Δ = 0.11, [0.00-0.22]; z = 1.92, p = 0.055) or flexibility training (Δ = 0.42, [-0.03 to 0.88]; z = 1.83, p = 0.68). CONCLUSION: RET significantly reduced depressive symptoms compared to active and inactive comparisons. Larger improvements were found among females and for interventions of ≤12 weeks in duration; similar magnitude improvements were found compared to aerobic exercise training and flexibility training. No trial has directly compared the effects of RET to pharmacotherapy or psychotherapy; comparisons to these frontline therapies are warranted in future research. Darragh O'Sullivan is funded by the Irish Research Council under award number GOIPG/2023/4158