What is known about the effects of exercise or training to reduce skeletal muscle impairments of patients with myotonic dystrophy type 1? A scoping review

BACKGROUND: Myotonic dystrophy type 1 (DM1) is a neuromuscular disease characterized by multisystemic involvements including a progressive loss of maximal muscle strength and muscle wasting. Poor lower-limb strength is an important factor explaining disrupted social participation of affected individuals. This review aims to map what is known about the effects of exercise and training programs undertaken to counteract skeletal muscle impairments in DM1 patients. METHODS: Medline, CINAHL and EMBASE databases were searched. Regarding study eligibility, title and abstract of 704 studies followed by 45 full articles were reviewed according to the following eligibility criteria. Inclusion: (1) humans with DM1 and (2) experimental protocol relying on exercise or training. Exclusion: (1) studies that do not evaluate skeletal muscle responses or adaptations, (2) reviews covering articles already included and (3) pharmacological intervention at the same time of exercise or training program. RESULTS: Twenty-one papers were selected for in-depth analysis. Different exercise or training protocols were found including: acute exercise, neuromuscular electric stimulation, strength training, aerobic training, balance training and multiple rehabilitation interventions. Seven studies reported clinical measurements only, five physiological parameters only and nine both types. CONCLUSION: This scoping review offers a complete summary of the current scientific literature on the effect of exercise and training in DM1 and a framework for future studies based on the concomitant evaluation of the several outcomes in present literature. Although there were a good number of studies focusing on clinical measurements, heterogeneity between studies does not allow to identify what are the adequate training parameters to obtain exercise or training-induced positive impacts on muscle function. Scientific literature is even more scarce regarding physiological parameters, where much more research is needed to understand the underlying mechanisms of exercise response in DM1. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12891-019-2458-7) contains supplementary material, which is available to authorized users.