Cardiorespiratory responses to exercise in patients with spinal muscular atrophy and limb-girdle dystrophy

Maximum oxygen consumption, maximum heart rate and maximum ventilation during cycle ergometer exercise were studied in individuals with spinal muscular atrophy (N = 8) and limb-girdle dystrophy (N = 8). The limiting factors in aerobic power may be related to loss of functional muscular mass rather than to changes in the oxygen transport system. There was no correlation between VO2 max values and muscle strength as determined by a manual test of the affected muscles recruited for bicycle exercise. The results, therefore, do not support the possibility of a correlation between these indices previously proposed on the basis of clinical evidence.