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Nature-based exercise therapies (surf or hike) reduce residual depression symptoms in service members with MDD, but sleep difficulties, low energy, and appetite changes commonly persist even among those who lose their diagnosis

In a secondary analysis of an RCT comparing weekly surf or hike therapy among 96 active duty service members with MDD, both interventions significantly improved depression symptoms. Among 88 completers, loss of MDD diagnosis reduced odds of most residual symptoms (ps ≤ .039), but sleep difficulties (56%), low energy (38%), and appetite changes (22%) remained common at postprogram even in those who lost diagnosis. Exercise type did not affect residual symptom odds.

Last updated: Aug 8, 2026•1 RCTs•📖 Read as article →

Evidence Score

Evidence Score44/100
Human RCT★★☆☆☆
Meta-analysis☆☆☆☆☆
Mechanism★★★★★
Safety★★★★☆
Confidencelow

Study Evidence

Study 1. Residual depression symptoms following nature-based exercise therapies among U.S. service members.

observational

Otis NP, Glassman LH, Kline AC, Kobayashi Elliott KT, Michalewicz-Kragh B, Walter KH · Frontiers in physiology (2026)

Participants: N/A
Duration: 8 weeks (postprogram) with 3-month follow-up
Intervention: Weekly nature-based exercise therapy (surf or hike) for 8 weeks
Outcome: Residual depression symptoms (e.g., sleep difficulties, low energy, appetite changes, suicidal ideation) at postprogram and 3-month follow-up; also residual PTSD symptoms in comorbid subgroup
Effect Size: N/A (odds ratios not reported in abstract)
Population: Active duty U.S. service members with major depressive disorder (MDD), including a subgroup with comorbid PTSD (n=58, 66%)

Result:

PubMed: 42548550DOI: 10.3389/fphys.2026.1788999

Mechanism Graph

Exercise therapy reduces overall depression severity
↓
Loss of MDD diagnosis reduces odds of most residual symptoms
↓
However, certain residual symptoms (sleep, energy, appetite) persist despite diagnosis loss
↓
Result: Additional strategies targeting these transdiagnostic residual symptoms may be needed

Limitations

  • ⚠Secondary analysis of an RCT, not designed to test residual symptom differences
  • ⚠No control group (both arms were active exercise interventions)
  • ⚠Residual symptom assessment based on single-item measures from a depression scale, not validated for individual symptom tracking

Frequently Asked Questions

What residual depression symptoms are most common after nature-based exercise therapy?▼

Sleep difficulties (56%), low energy (38%), and appetite changes (22%) were most common at postprogram among those who lost their MDD diagnosis.

Does the type of exercise (surf vs. hike) affect residual symptoms?▼

No, exercise therapy type was not related to the odds of any individual residual symptom (ps ≥ .225).

Does losing the MDD diagnosis reduce all residual symptoms?▼

Loss of diagnosis reduced odds of most residual symptoms (ps ≤ .039), but not suicidal ideation at 3-month follow-up (p = .088).

Are residual symptoms similar in those with comorbid PTSD?▼

Yes, similar patterns were seen, with sleep disturbance persisting in 42% of those who lost their PTSD diagnosis.

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References

  1. 1.Otis NP, Glassman LH, Kline AC, Kobayashi Elliott KT, Michalewicz-Kragh B, Walter KH. "Residual depression symptoms following nature-based exercise therapies among U.S. service members.." Frontiers in physiology, 2026. PMID: 42548550 DOI: 10.3389/fphys.2026.1788999
Disclaimer: This content is for educational purposes only and is not medical advice. Evidence scores reflect the quality and quantity of available research, not clinical recommendations. Always consult a healthcare professional before starting any supplement or intervention.