# Feasibility of ‘Muscle Movers’: a teacher-delivered program to support children’s participation in muscle-strengthening physical activity

## TL;DR

A program called Muscle Movers was tested to see if teachers can successfully lead muscle-strengthening activities for children in school.

## Contribution

This study demonstrates the feasibility of a teacher-led muscle-strengthening program for children, which could improve scalability.

## Key findings

- Teachers found the program highly acceptable and practical to implement.
- Students showed a moderate improvement in upper-body muscular endurance.
- Homework tasks were underutilized compared to other components of the program.

## Abstract

Muscle-strengthening activity (MSA) is beneficial for school-aged children, but most school-based MSA interventions have been delivered by external specialists or research staff, limiting scalability. We aimed to assess the feasibility of a teacher-delivered MSA intervention for children in advance of a future efficacy trial.

We conducted a single-group feasibility trial with two Stage 2 (i.e. grade 3–4) classes from one primary school in New South Wales, Australia. The 6-week Muscle Movers intervention included (i) enhanced PE lessons focused on foundational MSA skills (1 × 45 min/week), (ii) classroom energiser breaks (2 × 5 min/week), and (iii) active homework tasks (1 × 10 min/week). We assessed acceptability, implementation, adaptation, and practicality using survey and interview methods. We also assessed pre–post change in children’s perceived strength, upper-body muscular endurance, and lower-body muscular power. Data were analysed in SPSS (V.25) using descriptive statistics and paired-samples t-tests, with Cohen’s d as a measure of effect size.

Two female teachers (31 and 59 years) and 30 students (mean [SD] = 9.8 [0.6] years; 40% female) were enrolled. Acceptability was high for teachers (mean [SD] = 5.0 [0.0] out of 5) and students (mean [SD] = 4.1 [1.0] out of 5). Teachers implemented all PE lessons and more than double the intended energiser breaks (mean [SD] = 5.5 [2.1] per week). Conversely, homework task assignment (mean [SD] = 5.0 [1.4]) and completion (mean [SD] = 2.5 [0.7]) were lower than intended. Teachers reported high confidence to deliver the program and viewed it as practical and adaptable. We found a moderate increase in children’s push-up performance (mean [95%CI] = 2.2 repetitions [0.7 to 3.8]; d = 0.61), but no meaningful changes in perceived strength (mean [95%CI] = 0.1 units [- 0.1 to 0.4]; d = 0.22) or standing long jump (mean [95%CI] = - 1.4 cm [- 7.4 to 4.7]; d = - 0.09).

Muscle Movers was feasible for classroom teachers to implement in a primary school setting. The observed improvement in students’ upper-body muscular endurance should be confirmed using an appropriately powered randomised controlled trial.

Retrospectively registered with the Australian and New Zealand Clinical Trials Registry (ACTRN12625000703404).

The online version contains supplementary material available at 10.1186/s40814-025-01751-0.