Cardiovascular responses to a hot tub bath

This study was conducted to determine the cardiovascular effects of 15 minu tes of hot tub immersion at 39 degrees C. Five college-age subjects (4 male s and 1 female) volunteered to participate in this study. Assessments were made while sitting first in a chair for 5 minutes and then in the hot tub f or 15 minutes. Oxygen consumption (Vo(2)) and cardiac output (Q) measuremen ts were made using a Medical Graphics CPX/D metabolic analyzer. Cardiac out put was determined at minute 15 using the indirect CO2 rebreathing procedur e. The data were analyzed using the analysis of variance with repeated meas ures, which indicated that at minute 15, heart rate (HR) and Q were increas ed, which increased Vo(2) The increase in Q was due to the heart rate (HR) response and the decrease in systemic vascular resistance (SVR). Mean arter ial pressure (MAP) and systolic blood pressure (SBP) were decreased while d ouble product (DP) was increased. There were no changes in stroke volume (S V) or arteriovenous oxygen difference (a-vo(2) diff). These findings indica te that the HR and Q responses are necessary to the increase in metabolism (Vo(2)). Hot tube use within these time and temperature constraints should reduce concern over hot tub safety in college-age subjects.