ECSS Paris 2023: OP-AP29
INTRODUCTION: With exercise in the heat, impaired evaporative cooling from hypovolaemia may predispose Exertional Heat Illness (EHI), risking debility and even death. Non-classic congenital adrenal hyperplasia (NCCAH) is caused most commonly by mutations leading to deficiency in the adrenocortical enzyme 21 hydroxylase (21OHD) and, despite a carrier frequency of 1:25 or more, is one of the most under-recognised autosomal recessive disorders. Typical presenting features of NCCAH arise from adrenal androgen excess, however with sustained stress, parallel defects in gluco- and mineralocorticoid production might be observable. Under sustained heat load, this would have the potential to precipitate EHI from depletional hyponatraemia. METHODS: United Kingdom military personnel were recruited from three groups referred to a specialist heat illness clinic: those with no history of EHI (controls, n=16), those affected by EHI with no documented hyponatraemia (nEHI, n=16), and cases of EHI complicated by hyponatraemia during deployment from the UK to hot climates (hEHI, n=2). After defining VO2peak, exercising Heat Tolerance Test (HTT) was conducted at 60% relative intensity, in WBGT 27 degrees C. Responses were categorised as pass (heart rate and core temperature plateau) or fail (inability to demonstrate thermal equilibrium at 90 min). Blood was sampled for steroid analysis at rested baseline, post-VO2peak and post-HTT, and with Short SynACTHen Test (STT) to characterise adrenal reserve. On clinical grounds, EHI cases failing HTT were re-tested following a minimum of 12 weeks, and mutations causative of NCCAH, including 21OHD, were sought in hEHI. RESULTS: HTT was passed at first attempt by 15/16 controls and 11/16 nEHI, with 100% pass rate on re-testing. One hEHI passed HTT first-time and, on genotyping, exhibited carrier status for 21OHD. The other hEHI required two subsequent attempts to pass HTT. Upon re-deployment into climatic heat, he was again thermally intolerant and was referred back for HTT, which he passed, however he was found also to have NCCAH (21OHD homozygote). No participants were shown to have inadequate adrenal reserve in cooler UK conditions, including hEHI with 21OHD mutations. Nevertheless, significant shunting of steroid precursors away from cortisol and aldosterone production was shown in NCCAH, both with HTT and on SST. CONCLUSION: Genotyping for NCCAH caused by 21OHD and other related enzyme defects may be warranted in athletes and military personnel who develop EHI complicated by hyponatraemia, especially where preceding thermal stress was extreme and sustained. The positive predictive value of HTT for future heat intolerance requires further investigation in this population.
Read CV Mike StaceyECSS Paris 2023: OP-AP29
INTRODUCTION: There is evidence that heat acclimation is beneficial in females [1], but it is unclear if intermittent exercise in the heat elicits greater adaptation than work-rate matched continuous exercise. We therefore investigated two different short duration, intermittent work:recovery intervals (compared with continuous exercise) on females’ rectal and skin temperatures and heart rate during exercise in the heat. METHODS: Fourteen recreationally trained females (mean ± SEM: age 29.8 ± 1.7 yr; body mass 68.73 ± 1.51 kg; body surface area 1.80 ± 0.03 m2) completed three 60-min cycling-based sessions in the heat (~39°C, ~40% relative humidity, ~1.40 m.s-1 air speed) with mean external work rate matched between protocols (~239 W.m-2) designed to elicit a mean exercise intensity of ~60%V̇O2max. The exercise protocols were 1) continuous (CON), 2) 90:90-sec and 3) 30:30-sec work:recovery intervals. Key outcome measures of rectal temperature (Trec), skin temperature (Tskin; °C), and heart rate (HR; beats.min-1) were collected at 30-sec intervals and expressed as mean values over each 3-min block. The change in Trec and Tskin (end-exercise minus resting values) and change in HR (end of last work block minus resting values) were analysed using linear mixed models and Bonferroni post-hoc procedures were used to locate differences where appropriate. Results were considered statistically significant when p<0.05. RESULTS: Change in Trec was higher in 30:30-sec (1.56 ± 0.10°C) compared to CON (1.17 ± 0.11°C; p=0.001), but not between intermittent protocols (p=0.247) or between CON and 90:90-sec (p=0.141). There was no difference (all p>0.265) in Tskin for CON (4.51 ± 0.49°C), 90:90-sec (4.48 ± 0.50°C), or 30:30-sec protocols (5.03 ± 0.48°C). Change in HR at the end of the last work block was higher in 30:30-sec (105 ± 3 beats.min-1) compared to CON (96 ± 3 beats.min-1; p=0.016), but not between intermittent protocols (p=0.686) or between CON and 90:90-sec (p=0.302). CONCLUSION: Very short duration, intermittent work:recovery intervals elicited a greater change in Trec and HR compared to work rate-matched continuous exercise in the heat in females. It appears longer duration intervals do not demonstrate a beneficial thermoregulatory response in comparison to continuous exercise for females in the heat. This finding indicates that very short duration, intermittent work:recovery intervals may be an exercise mode to consider in female heat acclimation training protocols for team sports, as it elicits a greater thermal stimulus, possibly driving a faster heat adaptive response in females. 1. Kelly et al., Sports Med. (2023).
Read CV Monica KellyECSS Paris 2023: OP-AP29
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.
Read CV Carl JamesECSS Paris 2023: OP-AP29