Purpose: The purpose of the present study was to ascertain if repeated heat therapy sessions in a hot tub (40.5o C) would be tolerated by older adults and result in cardiovascular benefit. The secondary purpose was to identify the utility of a noninvasive hemodynamic monitor while submerged in hot water.Methods: Fifteen volunteers > 50 years old underwent 8-10 separate 45-minute hot tub session over 14 days. Participants had maximal oxygen consumption (VO2 max) and other cardiovascular data measured via exercise treadmill testing prior to and after all hot tub sessions. Participants also wore noninvasive fingertip volume clamp monitors while submerged in hot water that calculated systemic vascular resistance, heart rate, blood pressure and cardiac index in order to ascertain feasibility and utility of this data. Other laboratory studies were obtained pre- and post-intervention.Results: All participants completed the study protocol. We found no differences in the pre- to post-intervention VO2 max (p=0.842). The noninvasive hemodynamic monitors successfully recorded cardiac index, systemic vascular resistance, heart rate and blood pressure. Only cardiac index had a trend of significance (p=0.044) with a decrease from 4 L/min to 3.54 L/min, however much of this trend can be attributed to one participant. Exercise duration was longer post-hot tub therapy (571 seconds versus 551 seconds; p=0.026). There were no differences in laboratory measurements.Conclusions: Repeated heat therapy via a hot tub along with pre- and post-intervention exercise stress testing is tolerated by older participants. However, 8-10 hot tub sessions did not result in positive changes in cardiovascular fitness or laboratory values.
