Effects of high resistance training in patients with myotonic dystrophy

Nine ambulatory subjects with myotonic dystrophy participated in a supervis ed 12-week progressive high-resistance training program. Knee extensor musc les were trained 3 times a week with free weights, 3 x 10 repetitions at 80 % of 1RM, One leg was randomly chosen for training and the other served as control. Six patients completed the training program. In the trained leg, 1 RM increased from 16.4 +/- 3.4 kg to 21.8 +/- 2.6 kg (p=0.0002), There was no difference between pre- and post-training concentric or; eccentric isoki netic values at 30 degrees/second in either leg. Muscle biopsy from m. vast us lateralis in the trained leg revealed no systematic difference in the de gree of histopathological abnormalities before and after training. After tr aining, there was a tendency toward increase in cross-sectional area of typ e I muscle fibres. However, the number of subjects was too small to draw co nclusions regarding the effects of training on the histopathological change s. Magnetic resonance imaging revealed no difference in the m. quadriceps a rea after training. In conclusion, patients with myotonic dystrophy improve d their muscle strength without any observed negative side effects after a 12-week high-resistance training program.