Physiological response to treadmill walking in water at different speeds and temperatures

Introduction: The aim of this study was to examine the influence of temperature and speed on the physiological response to walking on a water-based treadmill. Methods: Six subjects walked on the treadmill for 30 minutes, at nine different combinations of water temperature and walking speed (30, 35, 40°C and 4, 5, 6 km hr-1), in a randomized order. Blood lactate concentration (BLa), heart rate (HR), oxygen uptake (VO2) rating of thermal sensation (RTS) and rating of perceived exertion (RPE), were recorded at rest in the water, prior to each test, every five minutes during each test and again at the end of a five minute recovery period. Results: Mean VO2 and BLa concentration significantly increased during each trial and with each increase in speed. BLa concentration significantly increased with an increase in water temperature from 30°C to 35°C. HR, RPE, and RTS significantly increased during each trial and with each increase in speed. RTS also increased significantly with increased temperature and HR significantly increased with an increase in temperature from 30°C to 40°C. Conclusions: Treadmill walking at increasing speed in water of increasing temperature provides an increased physiological stress above that normally found with laboratory-based treadmill exercise. This could provide a suitable rehabilitative activity for injured individuals.