# Lifestyle physical activity coaching in outpatients with major depressive disorder (PACOUTPAT): study protocol for a randomized controlled trial on physical activity, depression, and quality of life

## TL;DR

This study tests a new physical activity coaching program to improve depression and quality of life in outpatients with major depressive disorder.

## Contribution

A novel PA coaching approach combining affective and cognitive components is introduced and tested in a randomized controlled trial.

## Key findings

- The study investigates the effects of a 10-week PA coaching program supported by wearable technology.
- A follow-up phase of 26 weeks is added to examine long-term behavior change and mental health outcomes.
- Primary outcomes include changes in physical activity measured via accelerometers over time.

## Abstract

Major depressive disorder (MDD) is highly prevalent and associated with substantial disease burden and significantly reduced life expectancy. Physical activity (PA) has been shown to reduce depressive symptoms to a similar extent as antidepressant medication. Despite this evidence, individuals with MDD engage in lower levels of PA and exhibit higher levels of sedentary behavior. Structural, physical, and psychological barriers hinder PA engagement. PA coaching offers a promising strategy to overcome these barriers and promote sustainable behavior change. Previous research highlights the importance of addressing affective responses to PA in interventions. Moreover, the support of technology-based tools, such as wearables, seems promising. This study aims to investigate the short- and long-term effects of a new PA coaching approach on PA behavior, depression severity, and quality of life in outpatients with MDD. Potential mechanisms of behavior change and participant experiences are also examined.

This study uses a three-arm randomized controlled trial (RCT) design and is conducted at a psychiatric day clinic in German-speaking Switzerland. A total of 114 individuals aged 18 to 65 years with a clinical diagnosis of MDD (ICD-10: F32 and F33) are recruited on an ongoing basis and randomly assigned to one of three groups: (1) A 10-week PA coaching program based on interest and experience in PA, supported by a wearable smart ring for self-monitoring; (2) the same 10-week program extended by an additional, remote 26-week cognition-based coaching phase; or (3) a control group receiving treatment as usual along with written current PA guidelines. Data is collected at three measurement timepoints: 2-4 weeks after the start of day clinic treatment (baseline), after the 10-week coaching phase (post), and after a 6-month follow-up period (follow-up). The primary outcome is the change in device-measured PA over time (baseline, post, and follow-up), measured via Fibion® accelerometer, and analyzed using linear mixed models.

A new PA coaching program is introduced to counteract low PA levels observed in individuals with MDD. By combining affective with cognitive components of behavior change, the intervention aims to promote a sustainable increase in PA and ultimately improve mental and physical health and quality of life.

DRKS: DRKS00036209. Registered on 08 May 2025

The online version contains supplementary material available at 10.1186/s13063-026-09500-1.