Cardiovascular disease (CVD) is the leading cause of mortality in Aotearoa New Zealand, with hypertension being a major risk factor that remains difficult to manage with medication. Finnish sauna bathing (FSB), a widely practiced form of heat therapy, has been linked to lower risks of CVD, stroke, and overall mortality. Traditionally, FSB is combined with cold water immersion (CWI), but the combined effects of these therapies remain under explored. While sauna research often focuses on physiological aspects, this study aims to take a holistic approach to understanding its impact on cardiovascular health.

Cardiovascular disease (CVD) remains the leading cause of mortality and morbidity in Aotearoa New Zealand. High blood pressure is a significant risk factor for CVD, with nearly half of older adults in Aotearoa diagnosed with hypertension, and it being relatively intractable to attempts thus far at treatment via antihypertensive medications.

Finnish sauna bathing (FSB) is one form of heat therapy, characterised by the use of a wood-fired sauna in which water is thrown over hot stones to create steam. In Finland, the sauna is not only a common therapy but also deeply ingrained in the cultural fabric, with many households having their own sauna. Traditionally, saunas were communal places where people came together to relax and share experiences thus fostering social connections. Lifelong sauna use is associated with markedly lower risk for chronic diseases such as; CVD, stroke, and all-cause mortality. Integral to the FSB experience is the practice of cold water immersion (CWI) which typically involves a plunge into icy waters, or exposure to freezing temperatures, in between sauna bathing.

Sauna bathing is typically researched with a physiological / biomedical lens and in isolation, that is, the additive effects of sauna bathing and cold-induced adaptations from cold-water immersion are not well understood, highlighting a gap in this research area. Additionally, the health benefits of sauna are wide ranging, therefore our focus is to use a holistic lens to explore the impact of sauna bathing cardiovascular health.

Inclusion Criteria:

• SBP: 110-179 mmHg; DBP 60-99 mmHg)
• 18 - 70 y old.
• Participants who are prescribed anti-hypertensive or dyslipidaemia medications will be included but must be on a stable dose for at least 30 days.

Exclusion Criteria:

• stable or unstable angina
• recent myocardial infarction (<3 months)
• orthostatic hypotension
• severe aortic stenosis
• pregnancy
• acute infectious diseases
• rheumatoid arthritis in the acute inflammatory phase
• fever for any reason
• any other medical condition deemed a risk.