Dr Sven Hoekstra
Research Associate in Exercise and Rehabilitation Sciences - Sport, Exercise and Health Sciences
Sven is an Exercise and Rehabilitation scientist working within the Peter Harrison Centre for Disability Sport. His research aims to develop interventions to promote cardiometabolic health in people with a limited exercise capacity, such as individuals with a disability. Examples of strategies that he investigates in collaboration with clinical and community partners are heat therapy, neuromuscular electrical stimulation and upper-body exercise.
Turning up the heat – hot baths to improve health
Partly as a result of physical inactivity and the consumption of too many calories, it is estimated that 63% of the adult population in the UK is overweight or obese. Research in the past decades has revealed that fat not only adds to body mass, but also actively produces compounds that can damage other tissue in the body and result in chronic disease.
While exercise can help to maintain a healthy body mass and improve disease risk factors, not everyone is able to exercise regularly. My research has shown that heat therapy, using hot baths or the sauna, may also be a strategy to maintain or improve health.
The use of heat therapy to treat health conditions is not a new concept. In around 3000 B.C., Egyptian physicians used it as part of their breast cancer treatment, and it is estimated that the Ancient Greeks began using it for medicinal purposes around 550 B.C.
Hippocrates, often referred to as the “founder of modern medicine” already stated around 400 B.C.: “What medicines do not heal, the lance will; what the lance does not heal, fire will".
Perhaps somewhat surprisingly, the research underpinning the use of heat therapy for health promotion is still in its infancy. While studies in the early 2000s showed that heat therapy is effective in reducing the risk for type 2 diabetes and cardiovascular disease in animals, well-conducted studies in humans only began around a decade ago.
Research into the health promoting effects of heat therapy has predominantly focussed on two areas: its effect on blood vessel health (i.e. cardiovascular disease risk) and its effect on the body’s ability to take up blood sugar (i.e. type 2 diabetes risk).
My work has also demonstrated that a single heat therapy session induces many of the same beneficial responses observed after exercise, such as an increase in key markers of the immune system and blood flow in the arteries.
Despite these promising findings, I observed during my Ph.D. studies that heat therapy can be perceived as uncomfortable. This led to follow-up studies in my Postdoctoral positions, in which I aimed to implement cooling interventions to alleviate thermal discomfort during heat therapy without interfering with its beneficial effects. If successful, such interventions can help the wide-spread roll out of treatments in both clinical settings and the general population.
I found that too much cooling may interfere with the positive effects of heat therapy, but a simple fan aimed at the face during a hot bath alleviates thermal discomfort while maintaining the therapeutic benefits. So while my work incorporates a wide range of immunological, metabolic and physiological parameters using state-of-the-art facilities in the National Centre for Sport and Exercise Medicine, it can lead to simple, easy-to-use and relatively cheap methods to improve health.
Going forward, I aim to help promote the implementation of heat therapy in clinical and rehabilitation settings. For instance, through the Peter Harrison Centre for Disability Sport, my relationships with rehabilitation centres around the UK can facilitate its implementation in people with a spinal cord injury or other disabilities. In doing so, I hope to also extend the evidence base for the beneficial effects of heat therapy to additional health parameters specific to certain disabilities, such as chronic pain and pressure sores in people with a spinal cord injury.
My research journey
During my M.Sc. at Groningen University (The Netherlands) I got involved in disability sport through a national handcycle event called The HandbikeBattle. This research project made me acutely aware of the power of exercise and all its related facets (e.g. social interactions, having a goal in life), in particular among people with a disability. My Ph.D. in the Peter Harrison Centre for Disability Sport provided me with the opportunity to further pursue a career in disability sport and health research. While exercise remained part of my research focus, it was during this time that I started to explore heat therapy as an alternative or additional strategy to promote health; inspired by the many people I met during my studies that faced significant barriers to meet the exercise guidelines.
Following completion of my Ph.D. in 2019, I have held Postdoctoral positions in the Peter Harrison Centre for Disability Sport at Loughborough University and Wakayama Medical University in Japan. At Loughborough I have further investigated effective and tolerable heat therapy protocols. Alongside these studies, my research looks to gain more understanding into the consequences of a spinal cord injury on metabolic health and the response to physiological stress. Further, supported by a Kyoten Postdoctoral Fellowship from Wakayama Medical University, I have investigated the effects of exercise on chronic pain in mice. Together, I hope that the research I have conducted along this journey as well as my future work can contribute to more inclusive health promotion policies by developing effective strategies for people along the complete physical capacity spectrum.