Myotonic Dystrophy Type 1 and Resistance Exercise

Myotonic dystrophy type 1 (DM1) is an autosomal, dominantly inherited, muscular disease and the most common muscular dystrophy amongst adults. The disease is characterized by progressive myopathy and myotonia, first evident in the distal parts of the body: calves and forearms, further progressing towards proximal parts. A recent review by Voet and co-workers (2013) concludes that exercise is safe for DM1-patients, and based on our current knowledge, DM1-patients should be able to gain positive adaptations from exercise. However, the physiological outcomes of an exercise stimulus are not well studied in this population and because of alterations in important Ca2+ handling systems the recovery processes might be significantly different from healthy muscles. The aim of this study is to investigate the acute responses to moderate-heavy resistance exercise in DM1-patients. We aim to establish a timeline for recovery of muscle strength, measured as maximal voluntary contraction. In line with this, we want to investigate if any muscular damage has occurred with both direct and indirect measures, and possible mechanisms leading to muscle damage, i.e. impaired Ca2+ handling.