Oxygen uptake kinetics in older patients receiving postacute cardiac rehabilitation: effects of low-intensity aerobic training.

Abstract

Older patients who receive postacute cardiac rehabilitation improve their physical performance in terms of distance walked at the 6-min walk test. However, the slower and more complicated recovery, along with age-related chronic comorbidities, remarkably limits the intensity of aerobic training, which actually represents the core of cardiac rehabilitation. The aim of this study was to verify whether postacute cardiac rehabilitation also improves the cardiovascular adjustment to exercise, despite low-intensity aerobic training. Using a portable gas analyzer, we assessed the O(2) uptake kinetics during the 6-min walk test at the beginning and at the end of the rehabilitation in 84 patients aged 65 yrs and above. All patients significantly improved the distance walked at the 6-min walk test. The comparison of the time constants of O(2) uptake kinetics showed that 40% of patients also significantly improved the hemodynamic response to exercise. This improvement was independently associated with the report of sedentary lifestyle or low-intensity physical activity in the year before surgery and with longer time constants before physical training. Low-intensity aerobic training improves the cardiovascular adjustment to exercise selectively in patients with physical deconditioning. This confirms the notion that elderly frail patients are those who benefit most from cardiac rehabilitation.