Physical exercise has shown promising results as an adjuvant therapy for depression. However, follow-up information assessing its long-term effects after the exercise program is suspended, is scarce.

To assess depression and functional parameters at follow-up, 6 months after a population sample of patients with treatment-resistant Major Depressive Disorder (MDD) finished a moderate intensity 12 week exercise program.

Study design Prospective, randomized, two-arm, parallel assignment. Population 150 individuals diagnosed with treatment-resistant MDD were initially screened. Those meeting study criteria were randomized to one of two groups: control (N = 11) and aerobic exercise (N = 22). All participants maintained their usual pharmacotherapy. Study protocol Exercise group: moderate intensity exercise program for 12 weeks. Control group: regular daily activities. Follow-up After 12 weeks the exercise program was suspended, and patients were assessed after 3 and 6 months. Assessed parameters HAMD17, BDI, GAF, CGI-S.

47% of participants in the exercise group continued to exercise at follow-up. Those who continued to exercise at follow-up maintained the same depression and functional parameters they showed after the 12 week exercise program, which were all improved compared to the initial values (lower HAMD17, BDI and CGI-S and higher GAF, p < 0.05). Those who did not continue to exercise showed worse HAMD17, GAF and CGI-S (p < 0.05) at 6 months follow-up than at the end of the exercise program.

Results suggest that positive effects of exercise as an adjuvant therapy for treatment-resistant MDD patients only persist if the exercise is continued over time.