Residual depression symptoms following nature-based exercise therapies among U.S. service members

Across interventions for major depressive disorder (MDD), symptoms often persist after treatment. These residual symptoms increase risk for depression relapse and reduce quality of life. Exercise is a common adjunctive intervention for MDD with potential to reduce common residual depression symptoms, yet the frequencies and types of residual symptoms following exercise interventions have seldom been examined and could inform recommendations for maximizing response.

This study was a secondary analysis of a randomized clinical trial comparing weekly exercise therapy programs (i.e., surf or hike) among 96 active duty service members with MDD. Symptom measures were completed at preprogram, postprogram, and 3-month follow-up. Among the 88 service members who completed a postprogram assessment, analyses examined whether exercise therapy type and loss of diagnosis were related to the odds of reporting each residual depression symptom.

Both interventions significantly improved depression symptoms. Exercise therapy type was not related to the odds of any individual residual symptom (ps ≥ .225). Loss of MDD diagnosis reduced the odds of residual depression symptoms (ps ≤ .039), except for suicidal ideation at 3-month follow-up (p = .088). Sleep difficulties (56%), low energy (38%), and appetite changes (22%) remained common at postprogram among participants who lost their diagnosis. Secondary analyses examined residual posttraumatic stress disorder (PTSD) symptoms in the subgroup with this comorbidity (n = 58, 66%). PTSD results showed similar patterns, with sleep disturbance (42%) frequently persisting at postprogram even among those who lost their PTSD diagnosis.

Residual depression symptoms were commonly transdiagnostic and mirrored those reported following evidence-based depression treatments. Additional strategies for reducing residual symptoms following weekly exercise therapy may be warranted for maximum symptom reduction.