Ice Slurry Ingestion Increases Core Temperature Capacity and Running Time in the Heat

[Mike Bikov]

Med Sci Sports Exerc. 2009 Nov 27. [Epub ahead of print]
Ice Slurry Ingestion Increases Core Temperature Capacity and Running Time in the Heat.

Siegel R, Maté J, Brearley MB, Watson G, Nosaka K, Laursen PB.

1School of Exercise, Biomedical and Health Sciences, Edith Cowan University Joondalup, WA, Australia 2National Heat Training and Acclimatisation Centre, Northern Territory Institute of Sport.

PURPOSE:: To investigate the effect of ice slurry ingestion on thermoregulatory responses and sub-maximal running time in the heat. METHODS:: On two separate occasions, in a counterbalanced order, ten males ingested 7.5 g.kg of either ice slurry (-1 degrees C) or cold water (4 degrees C) before running to exhaustion at their first ventilatory threshold in a hot environment (34.0 +/- 0.2 degrees C, 54.9 +/- 5.9% RH). Rectal and skin temperatures, heart rate, sweating rate, and ratings of thermal sensation and perceived exertion were measured. RESULTS:: Running time was longer (P = 0.001) after ice slurry (50.2 +/- 8.5 min) versus cold water (40.7 +/- 7.2 min) ingestion. Prior to running, rectal temperature dropped 0.66 +/- 0.14 degrees C following ice slurry ingestion compared to 0.25 +/- 0.09 degrees C (P = 0.001) with cold water, and remained lower for the first 30 min of exercise. At exhaustion however, rectal temperature was higher (P = 0.001) with ice slurry (39.36 +/- 0.41 degrees C) versus cold water ingestion (39.05 +/- 0.37 degrees C). During exercise, mean skin temperature was similar between conditions (P = 0.992), as was heart rate (P = 0.122) and sweat rate (P = 0.242). Following ice slurry ingestion, subjects stored more heat during exercise (100.10 +/- 25.00 vs. 78.93 +/- 20.52 W.m; P = 0.005), and mean ratings of thermal sensation (P = 0.001) and perceived exertion (P = 0.022) were lower. CONCLUSION:: Compared with cold water, ice slurry ingestion lowered pre-exercise rectal temperature, increased sub-maximal endurance running time in the heat (+19 +/- 6%) and allowed rectal temperature to become higher at exhaustion. As such, ice slurry ingestion may be an effective and practical precooling maneuver for athletes competing in hot environments.​

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