Abstract
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 (Tgi) reduced by 0.5±0.2°C after ICE ingestion compared with 0.1±0.1°C (P<0.001) with
CON. During the run, the rate of rise in Tgi was greater (P=0.01) with ICE than with CON for the first 15 min. At the end of time-trial,
Tgi 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<0.001). Although ingestion of ice slurry resulted in a transient increase
in heat strain following a warm up routine, it is a practical and effective pre-competition
cooling manoeuvre to improve performance in warm and humid environments.
Key words
internal cooling - endurance - heat - thermoregulation