What do thermal indices lack to help predict heat-related risk in elite Athletics?

OBJECTIVES: This study aimed to characterise the frequency of exertional heat stroke (EHS), did-not-finish (DNF) and medical encounter (MED) outcomes in elite Athletics competitions, and to evaluate their association with environmental, individual and race-related variables. Particular attention was given to the wet bulb globe temperature (WBGT), a thermal index widely used by international federations to estimate athlete heat strain. METHODS: tests and negative binomial (NB) regressions were used to explore associations between outcomes (EHS, DNF, MED) and environmental, individual and race-related variables. The predictive ability of these variables was assessed using leave-one-out cross-validation to identify the best-performing univariable and multivariable models. RESULTS: EHS frequency was 8/1000 on average and 16/1000 when the WBGT was above 28.0°C, independent of sex (p=0.297) or discipline (p=0.980). DNF and MED were higher in marathon, racewalking and trail-running than shorter disciplines (p