Brief cold water immersion between sauna rounds lowers core temperature and heart rate

A small crossover study tested whether adding a short cold water immersion to the rest period between two sauna sessions changed how the body responded to the heat compared with resting in air alone. Participants who took the cold immersion break ended the second sauna round with meaningfully lower core temperatures, lower heart rates, and reported feeling less hot and more able to continue.

What the study found

This was a positive finding: adding a brief cold water immersion to the cooling break between two sauna bouts was associated with measurably lower physiological strain by the end of the session compared with air cooling alone. Core body temperature at the close of the second sauna round was roughly half a degree Celsius lower in the cold immersion condition, a difference the authors describe as large in effect-size terms. Heart rate followed a similar pattern, running about 17 beats per minute lower on average when cold immersion was included.

Skin temperature was also lower after cold immersion breaks, consistent with the core and heart-rate findings. Blood pressure results were more mixed: systolic pressure and mean arterial pressure did not differ meaningfully between the two conditions, while diastolic pressure was actually somewhat lower in the air-only condition at certain time points, a nuance the authors note without a clear mechanistic explanation.

On the perceptual side, participants reported feeling less hot and more willing to continue into the second sauna bout when cold immersion had been part of their break. Effect sizes for these subjective measures were similarly large, suggesting the difference was not trivial to the people experiencing it.

The authors frame the reduction in thermal and cardiovascular strain as potentially relevant to heat illness risk, though the study was not designed to measure actual adverse events and the sample was healthy and relatively young.

Limits worth knowing

The trial enrolled only 16 healthy adults with a mean age of 31, so findings may not extend to older individuals, those with cardiovascular conditions, or people unaccustomed to sauna. The protocol was conducted on a single visit per condition, meaning longer-term or repeated-session effects were not examined. The cold water immersion temperature and duration were fixed, so it is unknown whether different parameters would produce different results. No funding disclosures were identified in the available information. Subjective tolerance was self-reported, and the study was not powered or designed to assess clinical outcomes such as actual heat illness events.

About this entry. The Heartwood Review summarizes published, peer-reviewed research in its own words and links to the original source. It is not medical advice; consult a physician before beginning or changing any thermal or recovery practice. Findings summarized here describe the study cited, not any product sold by Teak & Marble Atelier. Corrections.