Long-term effects of exercise at different intensity levels on depression: A randomized controlled trial

Previous research has shown positive effects of exercise on depression but studies have mainly focused on the short-term effects; few have examined the long-term effect, especially with regard to differences in intensity. The aim of this study was to examine the long-term effects of prescribed exercise on depression, performed at three intensity levels. People aged 18-67years with mild to moderate depression (Patient Health Questionnaire-9 score of ≥10) participated in a single-blind, parallel randomized control trial lasting 12weeks (Sweden 2011-2013). Four arms were included: Treatment as usual (TAU, n=310), light (n=106), moderate (n=105) and vigorous exercise (n=99). Severity of depression was measured at baseline, post-treatment and 12-month follow-up using the Montgomery-Åsberg Depression Rating Scale (MADRS). Coefficients (β) and odds ratios were estimated using linear mixed models with time×group interactions. The results showed that at the 12month follow-up the light exercise group had significantly lower depression severity scores than the TAU (-1.9, 95% CI: -3.7, -0.04) and the moderate exercise group (-2.94 95% CI: -5.2, -0.7). The vigorous exercise group had significantly lower scores than the moderate exercise group only (-2.7, 95% CI: -4.9, -0.4). In conclusion, compared to usual care for depression, only light exercise resulted in significantly lower depression severity at 12-month follow-up. Both light and vigorous exercise was more effective than moderate exercise.

The study was registered with the German Clinical Trial Register (DRKS study ID: DRKS00008745).