Abstract
PURPOSE: To investigate cardiorespiratory responses during exercise stress tests using an aquatic treadmill and a land-based treadmill in patients with coronary artery disease (CAD).
METHODS: Twenty-one stable CAD patients were enrolled. All patients participated in 2 symptom-limited incremental exercise tests, using both an aquatic and a land treadmill. For the aquatic treadmill protocol, patients were submerged to the upper waist in 28[degrees]C water. The treadmill speed started at 2.0 km/h and increased 0.5 km/h every minute thereafter. For the land treadmill protocol, the speed and gradient were started at 2.4 km/h and 1.5%, respectively. The speed was increased by 0.3 km/h and grade by 1% every minute thereafter. Oxygen consumption (
O2), heart rate (HR), and respiratory exchange ratio were measured continuously and peak values recorded. Rating of perceived exertion, percentage of age-predicted maximal HR, and total exercise duration were also recorded.
RESULTS: Peak cardiorespiratory responses during both protocols were compared. The peak
O2 and peak HR did not show any significant differences. The peak respiratory exchange ratio was significantly greater using the land treadmill than the aquatic treadmill protocol. Rating of perceived exertion, age-predicted maximal HR percentage, and total exercise duration were similar for both protocols. There was a significant linear relationship between HR and
O2 with both protocols.
CONCLUSIONS: This study demonstrated that aquatic treadmill exercise elicits similar peak cardiorespiratory responses compared with land treadmill exercise, suggesting that aquatic treadmill exercise may be effective for CAD patients in cardiac rehabilitation.