Loughborough University research project highlights unique challenge of protecting open water swimmers from effects of extreme temperatures

The urgent issue of open water swimmers suffering from hypothermia (the body being too cold) or hyperthermia (the body being too hot) has been addressed  in a research project at Loughborough University in partnership with the European Aquatics medical committee.

Data gained at EA competitions between 2023 and 2025 has shown that athletes can suffer from hypothermia or hyperthermia within the same race, and with the same water temperature.

This highlights the unique challenge that swimmers and race medical and event teams face in protecting the health and performance of swimmers.

The findings demonstrate that swimmers should adopt preparation and mitigation strategies such as acclimation/acclimatisation to best protect their health and performance.

Meanwhile competition venues should be prepared to treat cold-related and heat-related health issues within the same race.

While much research has already been conducted to mitigate against the impact of high and low temperatures on athletes in land-based sports there has been a lack of information about its effect in swimming, where submersion in water can be relatively severe in terms of heat gain or loss.

Elite open-water swimming competitions are conducted within a broad water temperature range (World Aquatics water temperature range: 16-31°C).

Within this water temperature range heat-related and cold-related medical events have resulted in frequent drop-outs and, on occasions, fatalities.

This was the background to the establishment of this project, which was led by Loughborough University PhD researcher Kate Markey under the supervision of Dr Lee Taylor.

Core temperature data was collected using an ingestible telemetric thermometer capsule from four legs of the European Aquatics Open Water Swimming Cups from 2023-25 and the 2023 European Aquatics Junior Open Water Swimming Championships, totalling 60 performances across the project.

The capsule continuously records and stores temperature data and was ingested by the swimmers before the race (~7-hours).

At the end of the race, the capsule connects to an external data logging monitor, and the data is downloaded from the capsule and exported for analysis. 

The research team are committed to continuing their partnership with European Aquatics and further characterising elite open water swimmer’s core temperature responses in diverse water temperatures (particularly as rising ocean temperatures and global warming remain a threat to swimmer health), to inform health and performance optimisation strategies for open water swimming.

The team has placed on record its gratitude to all of the swimmers who participated in the research, without whom the project would not have been possible.

The team has also acknowledged the European Aquatics medical committee, and in particular its chair, Prof. Naama Constantini, for the continued support and invaluable contribution to this project. 

Mike Rowbottom for European Aquatics

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