Improving females' health and performance by mitigating heat strain
Lead Research Organisation:
University of Worcester
Department Name: School of Sport & Exercise Science
Abstract
Climate change refers to the long-term shift in global temperatures, which may occur naturally, but human activities relating to burning fossil fuels is considered a main driver. As a result, the frequency and intensity of heat waves is increasing, exposing humans to unseasonable and dangerously high temperatures which harms human health. In the UK during the five heat-periods in 2022, where temperatures exceeded 40 degree Celsius, 3,271 excess deaths were reported which is estimated to increase to over 7,000 by 2050. Furthermore, audits reveal six cases of heat illness per 100,000 in an occupational setting, two cases per 1,000 in military personnel, and nine cases per 100 in athletes. Heat illnesses are largely avoidable with the implementation of appropriate, effective, accessible, and sustainable heat mitigation strategies combined with appropriate education for more susceptible individuals.
To prepare for heat stress, consensus recommendations suggest individuals should exercise in the heat, for up to 14 occasions for >60-min, where core and skin temperatures are elevated and sweating is initiated (Racinais et al., 2015). This requires relocation to a hot climate or access to an environmental chamber, which can be costly and impractical. The widespread use of air conditioning is another approach widely used to help mitigate heat strain. However, the use of air conditioning is not accessible to some of the most vulnerable, in areas of poverty, and in occupations involving outside activity. Collectively, these heat mitigation strategies increase greenhouse gas emissions contributing to global warming and increasing the risk of future extreme heat events (Lane 2021). An improved understanding and utility of techniques for mitigating heat strain that are more sustainable, accessible, time efficient, and simple to administer such as adapting using hot water immersion, and cooling using electric fans, wetting the skin and cold-water immersion, has become an urgent research priority.
Males and females differ in their responses to heat stress (i.e., external heat load) largely due to females having a reduced sweating capacity, especially during periods of high heat loss requirements (i.e., during high intensity exercise). As such, females may reach dangerously high body temperatures quicker than males and consequently, have been more frequently diagnosed as heat intolerant. Hormonal fluctuations associated with the menstrual cycle modify responses to heat strain. For example, elevated progesterone concentrations during the luteal phase of the menstrual cycle (i.e., after ovulation before next period) increases resting body temperature, the onset threshold for sweating and the shift of blood to the skin surface for heat dissipation. Furthermore, perimenopausal and menopausal females experience additional heat sensitives, with the occurrence of hot flushes and night sweats which elevate their thermal discomfort. Despite known sex differences, audits reveal an under-representation of females as study participants, as such, heat mitigation guidelines, are underpinned almost exclusively by research conducted in men, without consideration of issues associated with the biological and phenotypical sex differences.
The overarching aim of this proposal is to support females to navigate extreme heat episodes. We will assess more sustainable and accessible methods compared to current consensus, e.g., hot water immersion to adapt to the heat and cooling the skin to manage the heat. We will then generate bespoke female heat mitigation guidelines and distribute these to the public through available platforms to improve females' health and performance.
To prepare for heat stress, consensus recommendations suggest individuals should exercise in the heat, for up to 14 occasions for >60-min, where core and skin temperatures are elevated and sweating is initiated (Racinais et al., 2015). This requires relocation to a hot climate or access to an environmental chamber, which can be costly and impractical. The widespread use of air conditioning is another approach widely used to help mitigate heat strain. However, the use of air conditioning is not accessible to some of the most vulnerable, in areas of poverty, and in occupations involving outside activity. Collectively, these heat mitigation strategies increase greenhouse gas emissions contributing to global warming and increasing the risk of future extreme heat events (Lane 2021). An improved understanding and utility of techniques for mitigating heat strain that are more sustainable, accessible, time efficient, and simple to administer such as adapting using hot water immersion, and cooling using electric fans, wetting the skin and cold-water immersion, has become an urgent research priority.
Males and females differ in their responses to heat stress (i.e., external heat load) largely due to females having a reduced sweating capacity, especially during periods of high heat loss requirements (i.e., during high intensity exercise). As such, females may reach dangerously high body temperatures quicker than males and consequently, have been more frequently diagnosed as heat intolerant. Hormonal fluctuations associated with the menstrual cycle modify responses to heat strain. For example, elevated progesterone concentrations during the luteal phase of the menstrual cycle (i.e., after ovulation before next period) increases resting body temperature, the onset threshold for sweating and the shift of blood to the skin surface for heat dissipation. Furthermore, perimenopausal and menopausal females experience additional heat sensitives, with the occurrence of hot flushes and night sweats which elevate their thermal discomfort. Despite known sex differences, audits reveal an under-representation of females as study participants, as such, heat mitigation guidelines, are underpinned almost exclusively by research conducted in men, without consideration of issues associated with the biological and phenotypical sex differences.
The overarching aim of this proposal is to support females to navigate extreme heat episodes. We will assess more sustainable and accessible methods compared to current consensus, e.g., hot water immersion to adapt to the heat and cooling the skin to manage the heat. We will then generate bespoke female heat mitigation guidelines and distribute these to the public through available platforms to improve females' health and performance.
