Hydration and cooling in elite athletes: relationship with performance, body mass loss and body temperatures during the Doha 2019 IAAF World Athletics Championships

Methods. Marathon and race-walk (20km and 50km) athletes (n=83, 36 women) completed a pre-race questionnaire. Pre- and post-race body weight (n=74), Tcore (n= 56) and Tsk (n= 49; thermography) were measured.

Results. Most athletes (93%) had a pre-planned drinking strategy [electrolytes (83%), carbohydrates (81%)] whilst ice-slurry was less common (11%; p<0.001). More males than females relied on electrolytes and carbohydrates (91-93% vs. 67-72%, p≤0.029). Drinking strategies were based on personal experience (91%) rather than external sources (p<0.001). Most athletes (80%) planned pre-cooling [ice-vests (53%), cold-towels (45%), neck-collars (21%) and ice-slurry (21%)] and/or mid-cooling [93%; head/face dousing (65%) and cold-water ingestion (52%)]. Menthol usage was negligible (1-2%). Pre-race Tcore was lower in athletes using ice vests (37.5±0.4ºC vs 37.8±0.3ºC, p=0.024). Tcore (pre-race 37.7±0.3ºC, post-race 39.6±0.6ºC) was independent of event, ranking or performance (p≥0.225). Pre-race Tsk was correlated with faster race completion (r=0.32, p=0.046) and was higher in non-finishers (DNF; 33.8±0.9ºC vs. 32.6±1.4 ºC, p=0.017). Body-mass loss was higher in males than females (-2.8±1.5% vs. - 1.3±1.6%, p<0.001), although not associated with performance.
Conclusion. Most athletes hydration strategies were pre-planned based on personal experience. Ice-vests were the most adopted pre-cooling and the only one minimizing Tcore, suggesting that event organisers should be cognisant of logistic (i.e. freezers). Dehydration was moderate and unrelated to performance. Pre-race Tsk was related to performance and DNF, suggesting that Tsk modulation should be incorporated into pre-race strategies