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Cardiovascular responses to a hot tub bath
T Boone1, T Westendorf, P Ayres
1The College of St. Scholastica, Department of Exercise Physiology, Duluth, Minnesota 55811, USA. Tboone2@css.edu
Summary
Hot tub immersion at 39°C for 15 minutes increases heart rate and cardiac output, boosting oxygen consumption in college-age adults. These findings suggest hot tub use is safe for this demographic within these parameters.
Area of Science:
- Cardiovascular Physiology
- Environmental Medicine
Background:
- Hot tub use is common, but its cardiovascular impact requires further understanding.
- Assessing physiological responses to heat immersion is crucial for safety guidelines.
Purpose of the Study:
- To investigate the cardiovascular effects of short-term hot tub immersion.
- To determine the impact of 39°C hot tub use on key hemodynamic and metabolic parameters in young adults.
Main Methods:
- Five college-age subjects underwent 5 minutes of seated rest followed by 15 minutes of 39°C hot tub immersion.
- Cardiovascular measurements included oxygen consumption (VO2), cardiac output (Q), heart rate (HR), systemic vascular resistance (SVR), mean arterial pressure (MAP), and systolic blood pressure (SBP).
- CO2 rebreathing method was used for cardiac output determination; data analyzed using ANOVA with repeated measures.
Main Results:
- Hot tub immersion significantly increased heart rate (HR), cardiac output (Q), and oxygen consumption (VO2).
- Increased cardiac output was attributed to elevated HR and decreased systemic vascular resistance (SVR).
- Mean arterial pressure (MAP) and systolic blood pressure (SBP) decreased, while double product (DP) increased; stroke volume (SV) and a-vO2 diff remained unchanged.
Conclusions:
- The observed increases in heart rate and cardiac output are essential for the elevated metabolic rate (VO2) during hot tub use.
- Hot tub immersion at 39°C for 15 minutes appears safe for college-age individuals, reducing concerns about potential cardiovascular risks.