Short-term aerobic training response in chronic myopathies

We have previously demonstrated that patients with mitochondrial myopathies can benefit from short-term aerobic exercise training. In this study, we c ompared the responses to short-term aerobic training of patients with mitoc hondrial myopathies, patients with nonmetabolic myopathies, and sedentary n ormal subjects. Training consisted of 8 weeks of treadmill exercise at 70% to 85% of estimated maximum heart rate reserve. All groups showed significa nt improvements in estimated aerobic capacity as well as heart rate and blo od lactate at submaximal exercise intensities. The increase in estimated ae robic capacity was greater in the mitochondrial myopathy patients than in t he other two groups. Phosphorus magnetic resonance spectroscopy demonstrate d increased oxidative capacity of muscle in patients with mitochondrial myo pathies in response to this training but not in patients with other, nonmet abolic myopathies or sedentary control subjects. A self-assessed measuremen t of functional status (SF-36) suggested improved quality of life associate d with the training. This study demonstrates that short-term aerobic traini ng at low intensity can benefit patients with nonmetabolic myopathies but t o a lesser extent than patients with mitochondrial myopathies. (C) 1999 Joh n Wiley & Sons, Inc.