As Western Europe experiences its hottest June on record and the UK Health Security Agency (UKHSA) issues heat health alerts across much of England, experts are exploring how regular sauna use could help the body cope with extreme temperatures. The concept of heat training, long utilised by elite athletes, is now being examined for its potential to protect the general public during increasingly frequent and severe heatwaves.
The science of heat training
Research suggests that repeated exposure to heat, such as through saunas or hot baths, can lead to physiological adaptations that improve the body’s tolerance to high temperatures. According to experts, effective heat training typically requires 40 to 60 minutes of heat exposure each day for at least four to six days. The benefits of this rigorous regimen are not permanent, however, and generally last for approximately a week after the exposure ceases.
Prof Jari Laukkanen, a cardiologist at the University of Eastern Finland who has conducted extensive research into the health benefits of saunas, explained the mechanisms behind these adaptations. The physiological changes cited include earlier and more efficient sweating, improved skin blood flow, an expansion of plasma volume, and reduced cardiovascular strain during subsequent heat exposure. These adaptations allow the body to cool itself more effectively and maintain a stable core temperature under stress.
“This is well established in sports physiology, where athletes deliberately use repeated heat exposure to improve heat tolerance before competing in hot environments,” Prof Laukkanen said. The translation of these sports science principles to everyday public health could offer a new tool in managing the impacts of extreme weather.
Ongoing research and public interest
The potential benefits of heat training for the general population are currently the subject of ongoing research. Dr Jessica Mee of the University of Worcester is actively recruiting participants to study whether regular hot water immersion could improve how the body responds to heat. This research aims to determine if the benefits seen in athletes can be replicated in ordinary individuals using accessible methods like hot baths.
Dr Mee noted that individuals who are accustomed to heat tend to manage their exposure more effectively, which may be as important as the physiological changes themselves. “People who are accustomed to heat pace themselves more sensibly, hydrate more consistently and recognise their own warning signs earlier,” she said. This behavioural adaptation is a crucial component of heat resilience.
Public interest in saunas remains strong, even during warmer weather. Nicola Pegues, head of operations at Community Sauna Baths in Hackney Wick, observed that while bookings initially fell as temperatures rose, they have since begun to return. The outdoor sites feature both saunas and cold plunges, allowing visitors to cycle between the two extremes. This practice of contrast therapy is popular among sauna enthusiasts and may contribute to the overall cardiovascular benefits.
Safety concerns and limitations
Despite the potential benefits of long-term heat training, experts caution against using saunas as an immediate remedy during a heatwave. There is currently limited evidence to suggest that visiting a sauna during a heatwave provides any direct protection against heat-related illnesses. In fact, adding additional heat stress to the body during an extreme weather event could be counterproductive and potentially dangerous.
“There is currently limited evidence that going to a sauna during a heatwave itself protects people from heat-related illness or other conditions,” Prof Laukkanen warned. The benefits are more likely to stem from regular, long-term heat exposure rather than acute use during periods of very hot weather. The key is to build up tolerance gradually before the extreme heat arrives.
Furthermore, saunas and hot baths pose significant safety concerns for individuals with certain medical conditions. Those with an acute illness or fever, unstable angina, a recent heart attack, or uncontrolled low blood pressure are strongly advised to avoid such exposure until they have been medically assessed or treated. The cardiovascular strain induced by the heat can exacerbate these conditions, making it essential for vulnerable individuals to consult healthcare professionals before beginning any heat training regimen.
As heat health alerts become a more common feature of the British summer, understanding how to safely and effectively build heat tolerance will be increasingly important. While saunas and hot baths offer a promising avenue for improving resilience, they must be used sensibly and with a clear understanding of their limitations and risks.
