Background and purpose: Elevated energy costs of hemiparetic gait contribute to functional disability after stroke, particularly in physically deconditioned older patients. We investigated the effects of 6 months of treadmill aerobic exercise training on the energy expenditure and cardiovascular demands of submaximal effort ambulation in stroke patients with chronic hemiparetic gait.
Methods: Nine older stroke patients with chronic hemiparetic gait were enrolled in a 6-month program of low-intensity aerobic exercise using a graded treadmill. Repeated measures of energy expenditure based on steady state oxygen consumption during a standardized 1-mph submaximal effort treadmill walking task were performed before and after training.
Results: Six months of exercise training produced significant reductions in energy expenditure (n = 9; 3.40 +/- 0.27 versus 2.72 +/- 0.25 kcal/min [mean +/- SEM]; P < .005) during a given submaximal effort treadmill walking task. Repeated measures analysis in the subset of patients (n = 8) tested at baseline and after 3 and 6 months revealed that reductions in energy expenditure were progressive (F = 11.1; P < .02) and that exercise-mediated declines in both oxygen consumption (F = 9.7; P < .02) and respiratory exchange ratio (F = 13.4; P < .01) occurred in a strong linear pattern. These stroke patients could perform the same standardized submaximal exercise task at progressively lower heart rates after 3 months (96 +/- 4 versus 87 +/- 4 beats per minute) and 6 months of training (82 +/- 4 beats per minute; F = 35.4; P < .002).
Conclusions: Six months of low-intensity treadmill endurance training produces substantial and progressive reductions in the energy expenditure and cardiovascular demands of walking in older patients with chronic hemiparetic stroke. This suggests that task-oriented aerobic exercise may improve functional mobility and the cardiovascular fitness profile in this population.