Real-Time Thermoregulatory and Biomechanical Monitoring to Prevent Heat Illness in International Triathlon

INTRODUCTION: Despite advancements in heat mitigation strategies for athletes, heat related illnesses continue to pose a major risk to athletes’ health, particularly in endurance sports. Expert groups and international sporting federations now advocate for athletes’ routine monitoring during elite competitions, to ensure their safety. Practical challenges of such initiatives are considerable in sports spanning large distances with multiple exercise modes. Addressing this need, we report on the deployment of wearable technologies for real-time athlete monitoring across multiple World Triathlon events, specifically the 2023 Long-Distance World Triathlon Multisport Championships (LDWTC, Ibiza) and World Triathlon Para Cup (Taranto). The project aims to (i) demonstrate that wearable technologies can help ensure athletes’ health and safety (ii) determine the most relevant sensors for use.

METHODS: At the LDWTC, three athletes were monitored. One used a full suite of sensors to measure: core body temperature (TCORE), run kinematics, skin temperature (TSKIN), and heart rate (HR), whilst two were only monitored with TCORE. For run kinematics analyses, the run segment was divided into three equal parts. Environmental conditions were monitored using portable meteorological stations. Data were communicated via a wrist-worn bracelet, transmitting via the cellular network to the cloud. At the Para Cup, seven elite para-triathletes (2 male PTWC [wheelchair users], 1 female [upper limb disability] and 1 male PTS [lower limb disability] and, 2 male and 1 female PTVI [visual impairments]) were monitored for combinations of TCORE, TSKIN, HR and run kinematics.

RESULTS: In Ibiza (ambient temperature 22-25°C), the highest TCORE recorded was 39.52°C (+3.3°C from rest). Across the three segments of the run, the athlete with foot sensors showed gradually shorter stride lengths (1.96 m, 1.72 m, 1.64 m), and increased contact times (233 ms, 251 ms, 259 ms). In Taranto (ambient temperature ~22°C), the highest recorded TCORE was 40.05°C (+2.53°C from rest). Mean core temperature (n=5) was 38.34 ± 0.45°C and mean peak temperature 39.1 ± 0.63°C (+ 1.71± 0.55°C from rest).

CONCLUSION: We implemented a novel multi-sensor monitoring solution during elite triathlon events. High core temperatures at the Para Cup (up to 40.05°C) underscore the need for real-time monitoring. Special attention should be paid to specific populations who are more sensitive to heat illnesses such as athletes with spinal cord injury, for whom real-time monitoring may be even more crucial. A foot-mounted inertial sensor characterised fatigue during the run phase. Further development of integrated multi-sensor approaches, encompassing thermal, cardiovascular, sudomotor, and biomechanical monitoring, combined with multi-location weather data, is needed to accurately predict and prevent heat-related illnesses within elite competition. Future studies in hot environments with a greater sample of athletes should be developed.