Association between thermal responses, medical events, performance, heat acclimation and health status in male and female elite athletes during the 2019 Doha World Athletics Championships

Abstract

Purpose: To determine associations between thermal responses, medical events, performance, heat acclimation and health status during a World Athletics Championships in hot-humid conditions.

Methods: From 305 marathon and race-walk starters, 83 completed a preparticipation questionnaire on health and acclimation. Core (T_core; ingestible pill) and skin (T_skin; thermal camera) temperatures were measured in-competition in 56 and 107 athletes, respectively. 70 in-race medical events were analysed retrospectively. Performance (% personal best) and did not finish (DNF) were extracted from official results.

Results: Peak T_core during competition reached 39.6°C±0.6°C (maximum 41.1°C). T_skin decreased from 32.2°C±1.3°C to 31.0°C±1.4°C during the races (p<0.001). T_core was not related to DNF (25% of starters) or medical events (p≥0.150), whereas T_skin, T_skin rate of decrease and T_core-to-T_skin gradient were (p≤0.029). A third of the athletes reported symptoms in the 10 days preceding the event, mainly insomnia, diarrhoea and stomach pain, with diarrhoea (9% of athletes) increasing the risk of in-race medical events (71% vs 17%, p<0.001). Athletes (63%) who performed 5-30 days heat acclimation before the competition: ranked better (18±13 vs 28±13, p=0.009), displayed a lower peak T_core (39.4°C±0.4°C vs 39.8°C±0.7°C, p=0.044) and larger in-race decrease in T_skin (-1.4°C±1.0°C vs -0.9°C±1.2°C, p=0.060), than non-acclimated athletes. Although not significant, they also showed lower DNF (19% vs 30%, p=0.273) and medical events (19% vs 32%, p=0.179).

Conclusion: T_skin, T_skin rate of decrease and T_core-to-T_skin gradient were important indicators of heat tolerance. While heat-acclimated athletes ranked better, recent diarrhoea represented a significant risk factor for DNF and in-race medical events.

Keywords: exercise; hot temperature.

Figure 1

Rain clouds of the core temperature, skin temperature and core to skin temperature gradient at the end of the races. Mean±SD and individual values for the did not finish (DNF)/finishers (top panels), and for the athletes being/not being admitted to the medical facility for an in-race illness (bottom panels); *p<0.05.

Figure 2

Recent illness (in the 10 days preceding the World Championships). *P<0.05.

Figure 3

Proportion of athletes who acclimated for 5–30 days ahead of the World Championships (top left), main methods for acclimation (bottom left) and effects on other variables (right panel). DNF, did not finish; HA, heat acclimation; Live, athletes declaring to live in a hot country; Medical, admittance to the medical facility for in-race illness; temp, temperature; 20KRW, 20 km race-walk; 50KRW, 50 km race-walk.