RESEARCH REPORTS: PDF OnlyA Comparison of the Effects of Underwater Treadmill Walking to Dry Land Treadmill Walking on Oxygen Consumption, Heart Rate, and Cardiac OutputByrne, Heidi K; Craig, Jill Napoletan; Willmore, Jack HAuthor Information HK Byrne, MS is Doctoral Candidate in Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX 78712. JN Craig, MS is Exercise Physiologist Research Consultant for AquaCiser®, Inc (Vale, CO) and Exercise Consultant at Hills Fitness Center, Austin, TX 78712. JH Wilmore, PhD is Professor in the Department of Kinesiology and Health Education, University of Texas at Austin, Austin, TX 78712. Address all correspondence to Ms. Heidi K. Byrne at Department of Kinesiology and Health Education, 222 Bellmont Hall, University of Texas at Austin, Austin, TX 78712. Grant sources: This project was funded by AquaCiser® Inc, Ferns/IIIe, and St. David's Hospital, Austin TX. Acknowledgments: The authors would like to thank AquaCiser® Inc., Ferno/IIIe, and St. David's Hospital for partial funding of this project. A special thanks is extended to Tim Skelly and Sharon Wentzel and others at St. David's Rehabilitation Center who assisted in the development and coordination of this research project. Thank you to all of the subjects who were willing to donate their time and energy to this study. Journal of Aquatic Physical Therapy: November 1996 - Volume 4 - Issue 3 - p 4-11 Buy Abstract The underwater treadmill (UT) is currently used as both a clinical and research modality to examine the effects of immersion. The purpose of this study was to compare the metabolic and cardiovascular responses to UT exercise versus responses to a conventional land treadmill (LT). Twenty healthy subjects (10 m/10 f, aged 21-38) volunteered to perform two similar exercise bouts, one on UT and one on LT. Subjects walked at both 2 and 3 mph, 0% grade. Expired gases were collected and analyzed. Heart rate (HR) was monitored. Cardiac output (𝑄̇) was measured using the carbon dioxide rebreathing method. Stroke volume (SV) was calculated as 𝑄̇/HR. Rating of perceived exertion (RPE) was recorded for each stage. Analyses of variance were used to compare differences with variable speeds, conditions, and genders. UT walking elicited greater cardiac output and stroke volume than the LT at both speeds. UT oxygen consumption was greater at both speeds, with greater variance at 3 mph. RPE was greater at 3 mph than 2 mph in both conditions, and greater on the UT than the LT. Analysis of data at a matched oxygen consumption value demonstrated HR to be significantly lower and SV higher during water exercise. Results suggest that HR is a poor indicator of aquatic exercise intensity; and that increasing the velocity of immersed ambulation results in a greater absolute workload than the same magnitude increase in land-based ambulation. © Williams & Wilkins 1996. All Rights Reserved.