Water exercise in coronary artery disease patients, effects on heart rate variability, and body composition: A randomized controlled trial.

BACKGROUND AND PURPOSE: It is important to assess the effectiveness and efficiency of water-based training programs in order to prescribe it as an alternative in cardiac rehabilitation for patients who have coronary artery disease (CAD). In these patients, autonomic dysfunction is an important physiological change strongly associated with adverse outcomes, morbidity, and mortality. Given that the beneficial effects of physical training in CAD patients have been traditionally evidenced with programs involving land-based aerobic exercises, this study aims to evaluate the effects of water aerobic exercise training (WAET) on the autonomic modulation of heart rate (HR) and body composition, in the rehabilitation of CAD patients.

METHODS: Twenty-six male subjects with CAD were randomly divided into a training group (n = 14), submitted to the WAET, and a control group (n = 12). The WAET consisted of 3 weekly sessions on alternate days, totalling 48 sessions. The analysis of HR variability was used to evaluate the autonomic modulation of HR, from the recording of R-R intervals for 15 min, at rest in the supine position, and the body composition was evaluated through the bioelectrical impedance analysis.

RESULTS: Only the training group participants had improvement in the HR variability indices; patterns without variation decreased (0V, p = .005) and an increase of patterns of two different variations (p < .001), Shannon entropy (p = .02), and normalized conditional entropy (p = .03), whereas the control group had an increase of 0V (p = .04) and a decrease of normalized conditional entropy (p = .01). All body composition variables remained unchanged.

CONCLUSIONS: The WAET protocol improved the cardiac autonomic modulation of patients with CAD and can be considered as exercise training strategy in cardiac rehabilitation programs.