Heat immersion researchers Ed Cole and Dr Andy Garrett


University of Hull researchers go global with research to assist athletes and the elderly

Researchers from the School of Sport, Exercise and Rehabilitation Sciences at the University of Hull have discovered new information on how people can deal with heat through short-term heat acclimation and it’s much more accessible than previously thought.

This research has been picked up by the Washington Post, after the first research study was published earlier this month. The study focused specifically on the elderly who are more vulnerable to heat-related illness. The results have provided much sought-after answers that can help people in high temperatures.

Heat can have devastating impacts on a whole range of people, with the older population (over 50s) having a greater mortality risk during heatwaves due to increased cardiovascular. The recent study, led by University of Hull PhD student Edward Cole, provides information on how short-term acclimation can reduce these issues.

Research from a review has shown that those who did hot-water immersion received comparable results with those who experienced traditional heat acclimation, by being exposed to high air temperatures.

Edward, a student in Sport, Health and Exercise Science in the Faculty of Health Sciences who is leading the research, said: “The reason hot water immersion is so interesting is that the conductive heat gained from water is much more than through the air. As the skin has direct contact with the water the heat energy is able to directly transfer from one to the other. This provides a much more intensive experience and allows participants to be heated up faster.”

This could have applications in sports performance for athletes wanting to prepare quickly for an event in a hot environment or perhaps in a military capacity when troops are required to deploy quickly to hot countries.

“Why this new technique is particularly interesting to us is that traditional heat acclimation has typically involved an exercise component in order to increase the speed at which core temperature rises. There are also other passive heat acclimation studies that could involve potential benefits however these often take more time. So in order to increase core temperature quickly without including an exercise component is where hot water immersion really comes into its own.”

If research into heat acclimation could be undertaken on a population who cannot undertake exercise (typically older and more sedentary people) then potentially this could lead to adaptations that allow that people to better cope with a heat wave or any other adverse heat event.

“Just using a hot water bath is something most people have access to. There are, however, some really big questions that need answering before this is recommended. For example, measuring core temperature is a key safety concern as we wouldn't want anyone to do this at home and give themselves hyperthermia. So finding a reliable and safe way to measure core temperature is key. Also how could hot water immersion be performed on the vulnerable population that needs its potential adaptations the most, safely? Most of the members of this group have many comorbidities that would have to be accounted for and investigated before this could become a regular thing.

“At its core, it is a very exciting concept that could go in many different directions and the reality is that we've only just begun to scratch the surface.”

Heat immersion research
Karina Jackson, Ed Cole and participants in heat immersion research.

The research team includes: Edward Cole, PhD Student in Sport, Health and Exercise Science; Dr Andrew Garrett, Senior Lecturer and Graduate Research Director at the School of Sport, Exercise and Rehabilitation Sciences; Dr Kate Donnan, Lecturer in Sport and Exercise Psychology; Dr Andrew Simpson, Lecturer in Exercise and Respiratory Physiology.

Masters student, Karina Jackson, who is studying for an MSc in Cardiac Rehabilitation, also assisted Ed with the study. Karina said: “This project has allowed me to do some hands-on science as part of my masters degree which is great experience for me.

“Working on this project with Ed has allowed me to collect a lot of data in a short space of time which sets me up in a great position to finish my Masters. Not only that but it has provided me with something to get fully invested in and dive head-first into an interesting topic. It has been a much more valuable experience for me in comparison to conducting a systematic review, for example.”

To learn more from their research studies, the team also launched a new focus with older adults (50-70 years). It’s a hot water immersion study involving Triathletes who were preparing for the Ironman in Lanzorate (reputed to be one of the hardest Ironman challenges in the world). The team has also worked with ex-serviceman, Darren Wilson, as he prepared to walk Death Valley in the USA for the Walking with the Wounded charity.

Darren’s challenge to walk 125 miles over 10 days and will be completely self-supported in the heat of the desert.

Dr Andrew Garrett, who is a Senior Lecturer in Exercise and Environmental Physiology and Ed’s PhD supervisor, said: “We have been quite fortunate that we have a number of older (50-73 years), healthy, male and female participants who are preparing for ultra-endurance events in hot countries.

“This includes the Iron triathlon (3.8Km open water swim; 180km cycle and marathon run of 42.2km) in Lanzarote on the hot Canary Islands.

“One of our participants, Darren Wilson, an ex-serviceman is travelling to Death Valley in the USA to walk 125 miles over 10 days, self-supported, in the intense heat of the desert.”

“All the participants will be faced with hot conditions and the work we are doing at the University, with repeated hot water immersion will partially adapt them to the heat when they arrive in their respective hot destinations.

“This will reduce the risk of heat stress and allow them to focus on the other challenging needs of ultra-endurance activity. From a health perspective, it may be that the use of the hot water immersion technique that people could do in their own homes, could be used as a method of preparing older adults for heat waves in this time of climate change.”

Dr Garrett is a founder member of the British Association of Sport and Exercise Sciences’ Climate Change Action Team. The research of the team is closely aligned with the Association to better understand the implications of climate change and the effect it will have on society.

Read the study: Short-term heat acclimation protocols for an aging population: Systematic review.

Purpose of the review and how it was conducted

The review contained a total of 179 participants who took part in short term heat acclimation protocols. The age of the participants ranged from 50 to 76.

The aim was to investigate the feasibility and efficacy of short-term heat acclimation (STHA) protocols undertaken by people aged 50+.

There were 12 studies in total. Ten studies used an environmental chamber, one study compared hot water immersion to the chamber and the remaining study used a hot water-perfused suit.

The results showed that eight of the studies reported a decrease in core temperature following the STHA.

Five studies demonstrated post-exercise changes in sweat rates and four studies showed decreases in skin temperature.

The differences reported in physiological markers suggest that STHA could be viable in an older population.

To help Ed with his ongoing research into the effects of summer heat on older adults, please complete this online survey, which takes approximately 10 minutes. Participants need to be over 50 to take part.

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