Abstract
PURPOSE: A primary goal of cardiac rehabilitation (CR) exercise is to increase cardiopulmonary fitness. The aim of this study was to identify characteristics of CR participants who fail to improve peak oxygen uptake (peak[latin capital V with dot above]O2).
METHODS: The study cohort included 385 consecutive patients with directly measured peak[latin capital V with dot above]O2 prior to and upon completion of CR. Patients were classified as a "nonimprover" if exit peak[latin capital V with dot above]O2 was less than or equal to entry peak[latin capital V with dot above]O2.
RESULTS: Eighty-one (21%) patients failed to improve peak[latin capital V with dot above]O2. Baseline characteristics predicting nonimprovement included the following: lower handgrip strength, lower peak exercise respiratory exchange ratio, a nonsurgical diagnosis, female status, and more medical comorbidities. The number of sessions attended and exercise duration were similar between groups. Nonimprovers, however, exercised at lower exercise intensity despite a similar rating of perceived exertion. By multivariate analysis, independent positive correlates of percentage change in peak[latin capital V with dot above]O2 included exercise training intensity and baseline handgrip strength. Negative correlates included baseline peak[latin capital V with dot above]O2, comorbidity score, self-reported physical function, and a diagnosis of diabetes (cumulative total r = 0.51, adjusted R2 = 0.26, P < .0001).
CONCLUSIONS: Twenty-one percent of CR participants failed to improve peak[latin capital V with dot above]O2 primarily due to exercise training performed at lower relative intensity despite a similar rating of perceived exertion. For patients with baseline characteristics associated with nonimprovement, alternative training protocols should be considered.