Exercise training improves strength in adults with myotonic dystrophy type 1 based on meta-analysis of 14 studies.

Myotonic dystrophy type 1 (DM1) is a progressive neuromuscular disorder characterized by muscle weakness, fatigue, reduced endurance, and impaired quality of life. This systematic review and meta-analysis aimed to evaluate the effects of exercise training on clinical and physiological outcomes in adults with DM1. Six databases were searched for studies published between 2003 and 2023. Randomized controlled trials, quasi-experimental studies, and longitudinal cohort studies involving adults with DM1 undergoing aerobic or resistance training were included, and risk of bias was assessed. Meta-analyses used standardized mean differences with fixed- or random-effects models based on heterogeneity. Fourteen studies were included. Most studies demonstrated low risk of bias. Only one study reported any adverse events, and the incidence of these events was similar in occurrence between the intervention and standard care only groups. Meta-analysis demonstrated a moderate improvement in strength (p = 0.022). Endurance showed a large but non-significant pooled effect (p = 0.14). Meta-analyses for fatigue (p = 0.49) and sleep (p > 0.05) were inconclusive. Narrative synthesis indicated improvements in most clinical and physiological outcomes, while sleep outcomes showed minimal or inconsistent changes across studies. Exercise training appears safe and provides moderate benefits for strength and selected clinical and physiological outcomes in adults with DM1. Future well-powered trials with standardized protocols are needed to optimize exercise prescription.