Long-Term Exercise Intervention in Patients with McArdle Disease: Clinical and Aerobic Fitness Benefits

Introduction The long-term effects of exercise in patients with McArdle disease-the paradigm of exercise intolerance-are unknown. This is an important question because the severity of the disease frequently increases with time. Purpose This study aimed to study the effects of a long-term exercise intervention on clinical and fitness-related outcomes in McArdle patients. Methods Seventeen patients (exercise group: n = 10, 6 male, 38 +/- 18 yr; control: n = 7, 4 male, 38 +/- 18 yr) participated in a 2-yr unsupervised intervention including moderate-intensity aerobic (cycle-ergometer exercise for 1 h) and resistance (high load-low repetition circuit) training on 5 and 2-3 d center dot wk(-1), respectively. Patients were assessed at baseline and postintervention. Besides safety, outcomes included clinical severity (e.g., exercise intolerance features) on a 0-3 scale (primary outcome), and aerobic fitness, gross muscle efficiency, and body composition (total/regional fat, muscle, and bone mass; secondary outcomes). Results The exercise program was safe and resulted in a reduction of 1 point (-1.0; 95% confidence interval, -1.6 to -0.5; P = 0.025) in clinical severity versus the control group, with 60% of participants in the exercise group becoming virtually asymptomatic and with no functional limitation in daily life activities. Compared with controls, the intervention induced significant and large benefits (all P < 0.05) in the workload eliciting the ventilatory threshold (both in absolute (watts, +37%) and relative units (watts per kilogram of total body mass or of lower-limb muscle mass, +44%)), peak oxygen uptake (in milliliters per kilogram per minute, +28%), and peak workload (in absolute (+27%) and relative units (+33%)). However, no significant changes were found for muscle efficiency or for any measure of body composition. Conclusions A 2-yr unsupervised intervention including aerobic and resistance exercise is safe and induces major benefits in the clinical course and aerobic fitness of patients with McArdle disease.

Automated summary

This study aimed to investigate the effects of a long-term exercise intervention on patients with McArdle disease. The results showed that a 2-year unsupervised exercise program was both safe and effective in improving the clinical course and aerobic fitness of these patients.