Cardiovascular Responses in a Whirlpool Bath at 40°C Versus User-Controlled Water Temperatures

Abstract

To compare cardiovascular responses in a whirlpool bath at 40 degrees C versus user-controlled water temperature (UCT). In an experimental study, six healthy men, 36 to 43 years of age, participated in two randomly assigned trials of whirlpool bath use for 25 minutes at 40 degrees C and UCT. Water temperature, esophageal temperature (Tes) heart rate (HR), systolic blood pressure (SBP), and perceived comfort were monitored before immersion and at 5-minute intervals during immersion. Although the mean water temperature during the UCT trial was slightly below 40 degrees C (39.4 +/- 2.0 degrees C), it varied considerably among subjects (from 36.5 +/- 2.1 degrees C to 42.5 +/- 1.7 degrees C). Peak Tes9 HR, and SBP were not significantly different between the two trials, although the UCT trial had greater variability. No adverse effects were observed. Mild or moderate overheating was reported by four subjects in the 40 degrees C trial and two subjects in the UCT trial, and mild chest pain, light-headedness, dyspnea, and nausea were reported by one subject during the UCT trial. A trend toward higher comfort ratings was noted in the UCT than in the 40 degrees C trial, especially during the final 10 minutes of immersion. These data show that cardiovascular responses to whirlpool bathing for 25 minutes at 40 degrees C are mild. In comparison with the 40 degrees C trial, peak Tes9, HR, and SBP under UCT conditions were not, on the average, significantly higher, although more variability existed among the subjects.