# The efficacy of an online exercise intervention for improving depressive symptoms among patients with subthreshold depression in primary care: protocol for a randomized controlled trial

## TL;DR

This study tests if an online exercise program can reduce depressive symptoms in primary care patients with subthreshold depression.

## Contribution

The study introduces a novel online exercise intervention for subthreshold depression in primary care settings.

## Key findings

- The intervention will assess depressive symptoms using the BDI-II at multiple time points.
- Secondary outcomes include anxiety, quality of life, and healthcare utilization.
- Findings may influence clinical guidelines and public policies for depression prevention.

## Abstract

Subthreshold depression is common in primary care and is associated with significant healthcare burden. There is emerging evidence for the benefits of Exercise can reduce depressive symptoms among people with diagnosed depression, but there is limited evidence for subthreshold depression in primary care setting. This study aims to examine the efficacy of a 12-week online instructor-led exercise intervention in reducing depressive symptoms among people with subthreshold depression in primary care, when compared to usual care control.

This 1:1 randomised controlled trial will enrol 260 participants with subthreshold depression randomizing into 2 groups (online exercise intervention versus usual care control). The intervention consists of twice-weekly 1-h exercise online classes over 12 weeks, which will be led by certified instructors. Data will be collected at baseline (T0), immediate post intervention (T1), 3-month post intervention (T2) and 9-month post intervention (T3). The primary outcome is depressive symptoms measured by the Chinese version of Beck Depression Inventory-II (BDI-II) at T1. Secondary outcomes include anxiety symptoms, quality of life, physical activity levels, feasibility and acceptability, medication use and health service utilization, and cost assessment. Intention-to-treat analysis will be performed.

The proposed study will assess the efficacy of online exercise intervention in improving subthreshold depressive symptoms in primary care. The findings will inform clinicians and policy makers concerning prevention of depression in primary care, and may lead to changes in the respective current guidelines and public policies.

This trial has been registered in the Chinese Clinical Trial Registry, with the registration number: ChiCTR2400087923. The date of registration is 2024–08-07.

The online version contains supplementary material available at 10.1186/s12888-025-06663-0.