Ice Slurry on Outdoor Running Performance in Heat

The efficacy of ingestion of ice slurry on actual outdoor endurance performance is unknown. This study aimed to investigate ice slurry ingestion as a cooling intervention before a 10 km outdoor running time-trial. Twelve participants ingested 8 g · kg  − 1 of either ice slurry ( − 1.4°C; ICE) or ambient temperature drink (30.9°C; CON) and performed a 15-min warm-up prior to a 10 km outdoor running time-trial (Wet Bulb Globe Temperature: 28.2±0.8°C). Mean performance time was faster with ICE (2 715±396 s) than CON (2 730±385 s; P=0.023). Gastrointestinal temperature (T gi ) reduced by 0.5±0.2°C after ICE ingestion compared with 0.1±0.1°C (P gi was greater (P=0.01) with ICE than with CON for the first 15 min. At the end of time-trial, T gi was higher with ICE (40.2±0.6°C) than CON (39.8±0.4°C, P=0.005). Ratings of thermal sensation were lower during the cooling phase and for the first kilometre of the run ( − 1.2±0.8; P