Assessment of muscular strength and functional capacity in the juvenile and adult myotonic dystrophy type 1 population: a 3-year follow-up study.

Introduction: Myotonic dystrophy type 1 (DM1) is a progressive, multisystemic, and autosomal dominant disease. Muscle wasting and weakness have been associated with impaired functional capacity and restricted social participation in affected individuals. The disease's presentation is very heterogenous and its progression is still under-documented.