Treadmill Aerobic Exercise Training Reduces the Energy Expenditure and Cardiovascular Demands of Hemiparetic Gait in Chronic Stroke Patients

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Abstract
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.