Research reveals health risks caused by swimmers’ core body temperatures during open water competitions 28 November 2024 EnvironmentGlobal sporting eventsHealth and medicineResearchResearch successSport Image provided by David Damijanovic/European Aquatics. A study led by VR³ÉÈËÊÓƵ has revealed divergent challenges caused by swimmers’ core body temperatures during elite open water swimming competitions. Elite open-water swimming competitions are conducted within a broad water temperature range (World Aquatics water temperature range: 16-31°C), where heat (hyperthermia) and cold (hypothermia)- related medical events, including fatalities and race dropouts, occur. The project, delivered in partnership with European Aquatic’s medical committee, showed that within the same race (and water temperature), clinical hypothermia – the body being too cold – and mild hyperthermia – the body being too hot – can co-present in the same elite cohort. Led by Loughborough PhD Researcher Kate Markey under the supervision of Dr Lee Taylor, participating athletes ingested a telemetric pill prior to competition which transmitted core temperature data via radio frequency back to a monitor. Thirty-four elite swimmers (20 males, 14 females) were studied. The maximum core temperature reading was 39.5°C (clinical hyperthermia is a core temperature of or above ≥40°C), which was recorded in two separate swimmers – one in a water temperature of 25.5°C and the other in 19.3°C. Core temperature responses were measured during 41 elite male and female swimmer’s races (7.5km and 10km) across four sperate European competitions: (i) the 2023 (Leg 1, Slovakia, water temperature: 18.2°C) and (ii) 2024 (Leg 1, Italy, water temperature: 19.5°C, and Leg 5, Croatia, water temperature: 18.9°C) European Aquatics Open Water Cup; and (iii) the 2023 Jnr European Open Water Swimming Championships (Greece, water temperature: 25.5°C). The research team also recorded another athlete (during the same race in 19.3°C water) registering a hypothermic body temperature of 34.6°C (clinical hypothermia is a core temperature <35°C). Another swimmer could not finish the race and withdrew due to cold-induced discomfort, requiring minor medical attention. Speaking about the findings, Kate Markey said: “The divergent body temperature responses within swimmers competing in the same water temperatures are very interesting. We are still exploring whether these responses are due to the preparation strategies adopted by the athletes. Our provisional data analyses do not suggest that athlete sex or their race completion time (e.g., how fast or slow they swam) were associated with body temperature responses.” Dr Lee Taylor added: “Kate has worked exceptionally hard to overcome the logistical challenges of collecting these data from a unique group of elite athletes. We are very grateful for the expert knowledge, guidance and sport-specific expertise afforded to us through collaboration with European Aquatics. “In particular, Prof Naama Constantini through her role as Chief Medical Officer of European Aquatics. To me, specific open water swimming focused education tailored for the range of stakeholders involved, including correct preparation strategies (e.g. acclimation/acclimatisation), are clearly important to protect these athletes’ health and performance. Such measures would help reduce observed medical events and race dropouts.” Prof Naama Constantini added: “European Aquatics is constantly seeking to protect athlete’s health and therefore supports research on the issue of temperature safety of open water swimmers.” All swimmers involved in the study received a report including their individual race results. The report also provides recommendations and strategies (e.g., pre-cooling/pre-heating, heat/cold acclimation/acclimatisation practises) based on the swimmers' race core temperature responses for future European/World open water competitions. European Aquatics remain dedicated to advancing research on the safety of upper and lower water temperatures and the use of wetsuits in various distances of open water swimming competitions. The research could have significant implications for reducing race drop-outs, optimising performance, and improving the safety of swimmers during competition. VR³ÉÈËÊÓƵ would like to place on record its gratitude to the European Aquatics medical committee, in particular, Prof. Naama Constantini, for their collaboration throughout the study. Loughborough athletes on the global stage Follow the successes of Loughborough-linked athletes who have been selected to represent their country. Notes for editors Press release reference number: 24/200 Loughborough is one of the country’s leading universities, with an international reputation for research that matters, excellence in teaching, strong links with industry, and unrivalled achievement in sport and its underpinning academic disciplines. It has been awarded five stars in the independent QS Stars university rating scheme and named the best university in the world for sports-related subjects in the 2024 QS World University Rankings – the eighth year running. Loughborough is ranked 6th in The UK Complete University Guide 2025, 10th in the Guardian University League Table 2025 and 10th in the Times and Sunday Times Good University Guide 2025. Loughborough was also named University of the Year for Sport in the Times and Sunday Times Good University Guide 2025 - the fourth time it has been awarded the prestigious title. Loughborough is consistently ranked in the top twenty of UK universities in the Times Higher Education’s ‘table of tables’, and in the VR³ÉÈËÊÓƵ Framework (REF) 2021 over 90% of its research was rated as ‘world-leading’ or ‘internationally-excellent’. In recognition of its contribution to the sector, Loughborough has been awarded seven Queen's Anniversary Prizes. The VR³ÉÈËÊÓƵ London campus is based on the Queen Elizabeth Olympic Park and offers postgraduate and executive-level education, as well as research and enterprise opportunities. It is home to influential thought leaders, pioneering researchers and creative innovators who provide students with the highest quality of teaching and the very latest in modern thinking.