Résumé
Objectives Core temperature (T CORE ), skin temperature (T TORSO ) and running kinematics were measured across different athlete categories at a World Cup Sprint Triathlon, occurring during a heatwave (~ 25-31 °C Wet Bulb Globe Temperature [WBGT]). Methods Sixty-six triathletes participated: 21 World Cup (7 females), 32 Hong Kong-Elite (HK-Elite; 8 females) and 13 Amateur (6 females). Results Seventeen triathletes displayed a T CORE > 40.0 °C and two > 41.0 °C. Peak T CORE was not different between athlete categories (World Cup: 39.7 ± 0.6 °C; HK-Elite: 39.9 ± 0.8 °C; Amateur: 39.5 ± 0.8 °C; p = 0.357). However, there was an interaction between race phase and category (p = 0.001). Changes in T CORE for World Cup (2.4 ± 0.4 °C) and HK-Elite (2.5 ± 1.0 °C) were greater than for Amateurs (1.5 ± 0.7 °C). Peak T TORSO was higher in HK-Elites during afternoon races compared with morning World Cup races (p < 0.001). T TORSO reduced during the swim (p bonf < 0.001), then increased during the bike (p bonf < 0.001) but not run (p bonf = 1.00). World Cup athletes (3.15 ± 0.23 m) displayed longer strides (HK-Elites: 2.64 ± 0.35 m; Amateurs: 2.18 ± 0.30 m; p bonf < 0.001), shorter contact times (209.3 ± 13.7 ms; HK-Elites: 237.8 ± 23.0 ms; Amateurs: 262.9 ± 31.0 ms, p bonf < 0.001) and higher stride frequency (182.9 ± 6.3 strides.min -1 ) than HK-Elites (173.9 ± 6.8 strides.min -1 ) and Amateurs (173.2 ± 8.7 strides.min -1 , p bonf < 0.001), which were comparable. There were no biomechanical changes over time and no interactions. Conclusion Different athlete categories displayed comparable peak T CORE responses. Amateur triathletes tolerated T CORE > 40.0 °C without heat illness symptoms. T CORE may rise > 41 °C during a sprint triathlon held under Blue flag conditions (~ 26 °C WBGT), questioning the suitability of sprint-distance triathlons as a safer alternative to Olympic-distance triathlons under Red/Black flag conditions (> 30.1 °C WBGT).