# An exercise intervention in children and young adults with McArdle disease: feasibility, acceptability, and clinical outcomes

## TL;DR

A 12-week exercise program for children and young adults with McArdle disease was found to be safe and acceptable, though it did not significantly improve aerobic capacity or strength.

## Contribution

This study is the first to evaluate the feasibility and safety of structured exercise in younger McArdle disease patients.

## Key findings

- The exercise intervention was feasible and acceptable, with four out of five participants completing 70% of sessions.
- No significant improvements in aerobic capacity or strength were observed, but some individual benefits were noted.
- Mild rhabdomyolysis occurred in four participants, but no hospitalizations were required.

## Abstract

Patients with McArdle disease have reduced exercise capacity. Structured exercise programs in adults with McArdle disease can improve aerobic capacity and strength. However, structured exercise has not been evaluated in younger populations. Our aim was to determine the safety, feasibility, and acceptability of an exercise intervention in children and young adults with McArdle disease.

Children and young adults aged 5–30 years with McArdle disease were recruited through metabolic clinics in New South Wales, Australia, to complete a remote, supervised 12-week exercise intervention. Pre and/or post intervention, participants completed a treadmill cardiopulmonary exercise test (CPET), strength testing, habitual physical activity monitoring, a quality-of-life questionnaire, acceptability questionnaire, muscular Near Infrared Spectroscopy (NIRS), and blood samples.

Five out of 10 eligible participants, with a median age of 17 years (range 13–29), were enrolled. Four met the feasibility target of 70% completed exercise sessions. Four episodes of mild rhabdomyolysis were reported during the study, but no participant required hospital admission. All participants reported they would participate in similar programs in the future. No significant changes were found in aerobic capacity, strength, habitual physical activity levels or quality of life. Trends were observed for lower perceived pain during CPET, and improved leg press. NIRS indicated a possible trend for improved muscle oxygen utilisation.

A 12-week remotely delivered exercise intervention was found to be feasible, safe, and acceptable to children and young adults with McArdle disease. Although improvements to aerobic capacity and strength were not elicited, individual clinical benefits may have occurred.

An exercise intervention in children and young adults with McArdle disease is feasible, safe, and acceptable, and may elicit individual clinical benefits.

The online version contains supplementary material available at 10.1186/s13023-026-04222-8.