- A new study reveals that encapsulated heating methods significantly increase heart rates and cardiac strain compared to natural heat exposure like those experienced during hot weathers
- Understanding how extreme heat impacts heart function is crucial for developing effective strategies to protect vulnerable groups, especially as global temperatures continue to rise
Scientists have been testing how heat affects our hearts for years. But here's the thing: the most commonly used method might not provide much insight into what happens to the heart during heat waves.
A new study led by the University of Ottawa , with researchers from the University of Portsmouth , Harvard University , University of Otago , and the Institute for Exercise and Environmental Medicine , has revealed critical insights into how we test extreme heat's impact on heart function.
With rising global temperatures, understanding these effects is crucial for protecting public health, especially during heat waves.
The research, published in Nature Communications , analysed data from over 400 laboratory studies involving more than 6,800 participants. It highlights how different heating methods affect the heart's performance under heat stress.
It is well established that prolonged heat stress causes various cardiovascular issues in humans. With global temperatures and the incidences of heat waves rising, this poses a great concern; particularly for individuals and locations most vulnerable to heat stress
Dr Joe Costello, University of Portsmouth's Extreme Environments Laboratories
Co-author, Dr Joe Costello from the University of Portsmouth's Extreme Environments Laboratories , said: "It is well established that prolonged heat stress causes various cardiovascular issues in humans. With global temperatures and the incidences of heat waves rising, this poses a great concern; particularly for individuals and locations most vulnerable to heat stress.
"This extremely large study highlights that there is an urgent need to develop and refine empirical physiological models in both laboratories and natural settings. These models can then be used to facilitate and inform urgently required heat-health action plans and policies."
Robert Meade , who was a postdoctoral fellow at Ottawa's Human and Environmental Physiology Research Unit and lead author of the study, added: "Our study shows that exposure to encapsulated heating methods, like water-perfused suits or hot water immersion, can lead to significantly increased heart rates, blood pressures, and cardiac strain when compared to natural heat exposures, like those experienced during hot weather."
When exposed to heat, the body may struggle to function normally, potentially resulting in serious cardiovascular issues. To cool down, the body increases blood flow to the skin, leading to higher heart rates and increased cardiac workloads. The resultant increase in strain on the heart can pose a significant risk for vulnerable groups, including older adults and individuals with pre-existing heart conditions.
The study revealed that the most common heating method, suits that perfuse large volumes of hot water directly over the skin, may result in rapid overheating and exacerbated increases in cardiac strain.
In contrast, participants exposed to climate-controlled environments simulating hot weather or heat waves exhibited distinct cardiac responses that are more applicable to real-life scenarios.
The research offers vital data that can be used to design laboratory-studies that will more easily translate to the real world to enhance public health strategies.
The scientists behind the study hope their findings will influence how health agencies develop strategies to protect people during extreme heat events. They are now heading back to the drawing board, ready to figure out what really happens when the mercury rises - not in the lab, but in the real world where it matters most.
Glen Kenny , a full professor of physiology at uOttawa's Faculty of Health Sciences and Director of the Human and Environmental Physiology Research Unit, emphasised the importance of these findings: "As temperatures continue to rise, we need to understand how heat affects heart health. This research helps us address the physiological challenges posed by heat and will inform how we protect individuals during extreme weather events."
The University of Portsmouth's Extreme Environments Laboratories (EEL) support areas such as sport, product development, emergency rescue, military training, polar exploration, and film and TV production.
Researchers regularly collaborate with external organisations for research and training, including the Ministry of Defence, the Royal Society for the Prevention of Accidents, the Royal National Lifeboat Institution (RNLI), and Olympic and Paralympic athletes.
