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Investigating the health benefits of hot water immersion as an adjunct to exercise

Investigating the health benefits of hot water immersion as an adjunct to exercise


Society for Endocrinology 


Dr Tom Cullen, Dr Neil Clarke, Dr Doug Thake, Dr Matt Hill, Mr Campbell Menzies, Mr Charles Steward


Dr Chris Pugh - Cardiff Metropolitan University


1 April 2022 to 31 March 2023



Project overview

It is estimated that inactivity is associated with 11.6% of all-cause mortality in the UK and costs the NHS an estimated £700 million annually. Despite exercise being routinely recommended and prescribed by healthcare practitioners, older adults generally become less active as they age leading to an increased risk of non-communicable diseases such as obesity, type 2 diabetes miletus (T2D) and cardiovascular disease. Despite the efficacy, a large proportion of adults do not exercise due to tiredness, pain, lack of time and motivation. As such, more accessible alternative or adjunct therapies that elicit similar benefits to exercise are particularly important to investigate.

In this regard, there has been a surge of interest in the potential for heat therapy (such as sauna and hot tub bathing) as an alternative therapy for sedentary populations. Recent work from our group highlighted that heat therapy can act as an exercise mimetic, inducing a range of acute cardiometabolic, vascular and anti-inflammatory effects which are thought to underpin the health benefits of exercise. Initial studies have demonstrated the efficacy of heat as a therapeutic intervention particularly in diseases which are exacerbated by physical inactivity including T2D, polycystic ovary syndrome and heart failure. However, there are significant gaps in our understanding of the potential mechanisms by which heat therapy may exerts its benefits. Importantly, there is very little research on the cytokine and endocrine responses to heating, which are known to play an important role in the metabolic and anti-inflammatory benefits of exercise.

This project will provide further understanding of the physiological mechanisms by which passive heating may improve metabolic health and reduce the risk of diseases such as T2D, obesity and cardiovascular disease. The intention is that, in the future, heat therapy may be offered as an alternative (or adjunct) to exercise for those who will not or cannot adhere to it sufficiently.

Project objectives

Assess cytokine and encrine responses to acute bouts of exercise, with and without passive heating.

Identify a series of physiological and molecular markers enhanced by passive heating which are associated with positive health adaptations of exercise.

Impact statement 

This work will form the basis of empirical evidence to develop this emerging field. From a health perspective this work will inform and develop a novel area of  complimentary therapy for populations who struggle to meet national exercise guidelines. Further to this, the proposed intervention is relatively cheap and highly accessible, representing an attractive home-based therapy. This may not only improve individuals health, but also wellbeing and quality of life while potentially easing the associated economic costs of healthcare.


Cullen, T., Clarke, N. D., Hill, M., Menzies, C., Pugh, C. J. A., Steward, C. J., & Thake, C. D. (2020). The health benefits of passive heating and exercise: to what extent do the mechanisms overlap. Journal of Applied Physiology.

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