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.

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; ingestible pill) and skin (T; 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 during competition reached 39.6°C±0.6°C (maximum 41.1°C). T decreased from 32.2°C±1.3°C to 31.0°C±1.4°C during the races (p<0.001). T was not related to DNF (25% of starters) or medical events (p≥0.150), whereas T, T rate of decrease and T-to-T 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 (39.4°C±0.4°C vs 39.8°C±0.7°C, p=0.044) and larger in-race decrease in T (-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, T rate of decrease and T-to-T 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.