Strength training rescues mitochondrial dysfunction in skeletal muscle of patients with myotonic dystrophy type 1

Abstract

AbstractMyotonic dystrophy type 1 (DM1) is a neuromuscular disorder, for which no cure exists. This study investigates the effects of 12-week strength training on mitochondrial oxidative phosphorylation in skeletal muscle in a cohort of DM1 patients (n=11, males) in comparison to untrained sex-matched healthy subjects. Immunofluorescence was used to assess protein levels of key respiratory chain subunits of complex I (CI) and complex IV (CIV), and markers of mitochondrial mass and cell membrane in individual myofibers sampled from biopsies. We classified each patient myofiber as having normal, low or high levels of CI and CIV and compared the proportions of affected fibers before and after exercise training. The significance of changes observed between pre- and post-exercise training within patients was estimated using a permutation test.At baseline, DM1 patients present with significantly decreased mitochondrial mass, and isolated or combined CI and CIV deficiency. After strength training, in most patients a significant increase in mitochondrial mass was observed, and all patients showed a significant increase in CI and/or CIV protein levels. Remarkably, 12-week strength training is sufficient to partially rescue mitochondrial dysfunction in DM1 patients, suggesting exercise as an inexpensive and accessible therapy option.