# High-intensity interval training may reduce depressive symptoms in individuals with schizophrenia, putatively through improved VO(2)max: A randomized controlled trial

PMID: 36003983
Journal: Frontiers in psychiatry
Published: 2022
Authors: Bang-Kittilsen G, Engh JA, Holst R, Holmen TL, Bigseth TT, Andersen E, Mordal J, Egeland J

## Question

Does supervised treadmill HIIT reduce depressive and other symptom dimensions in schizophrenia compared with an active video-game control, and is any depressive-symptom effect mediated by VO2max change?

## Summary

In an observer-blinded randomized trial of outpatients with schizophrenia, 12 weeks of supervised treadmill HIIT reduced PANSS depressive symptoms more than supervised active video gaming, with the effect persisting at 4-month follow-up. Other psychotic symptom dimensions did not show clear between-group benefits, and mediation by VO2max was not confirmed.

## Population

- Outpatients with DSM-5 schizophrenia.
- Sample size: 82
- Age: HIIT mean 36.6 years; active video gaming mean 37.5 years
- Sex: HIIT 61% men; active video gaming 62% men
- Fitness level: VO2max measured for stratification; baseline fitness details not summarized here
- Health status: Schizophrenia outpatients, mostly using antipsychotic medication

## Methodology

- Observer-blinded randomized controlled trial
- 12-week intervention plus 4-month follow-up
- Supervised outpatient exercise/active gaming sessions
- Randomized and controlled study design.

## Protocol

- Supervised treadmill HIIT.
- Modality: Treadmill walking/running.
- Work intervals: 4 min.
- Recovery: 3 min active recovery.
- Sets or repetitions: 4 intervals.
- Intensity: 85-95% HRmax during intervals; about 70% HRmax recovery.
- Session duration: About 40 min.
- Frequency: 2 sessions/week.
- Program length: 12 weeks.
- Progression: No explicit progression reported.
- Active video gaming.
- Modality: Nintendo Wii sports bowling, golf, and tennis.
- Intensity: Active gaming control; not HIIT.
- Session duration: 45 min.
- Frequency: 2 sessions/week.
- Program length: 12 weeks.
- Progression: None reported.

## Outcomes

### PANSS depressed
Status: improved
HIIT reduced PANSS depressive symptoms more than active video gaming, and the difference persisted at follow-up.

Group x time post estimate -1.03, SE .35, 95% CI -1.71 to -0.35, p=0.003, d=0.37.

### CDSS
Status: mixed
CDSS did not differ post-intervention but favored HIIT at follow-up.

Post p=0.320; follow-up p=0.032.

### Other symptoms
Status: no clear change
PANSS total and most symptom dimensions did not show significant between-group improvement.

Positive symptoms showed a small follow-up reduction but no group difference; negative, disorganized, and excited factors were stable.

### VO2max mediation
Status: unclear
VO2max change correlated with depressive symptom change, but direct, indirect, and moderated mediation effects were not statistically significant.

Moderated mediation trend estimate 0.4, CI -1.188 to 0.087.

## Practical Insights

- Classic 4 x 4 treadmill HIIT may have depressive-symptom benefits in schizophrenia when supervised by sport and mental-health staff.
- Mental-health claims should be limited to depressive symptoms rather than broad schizophrenia symptom improvement.

## Limitations

- Active comparator prevents inference versus no-treatment control
- Sample smaller than planned
- Mediation analysis underpowered
- No Bonferroni correction
- Add-on to antipsychotic medication and usual care

## Safety And Adherence

- No harm from HIIT was reported in the article.
- Participants with pregnancy or medical conditions incompatible with exercise were excluded.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36003983/) (pubmed)
- [DOI](https://doi.org/10.3389/fpsyt.2022.921689) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9394183/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.