Phillips, S. E., Mims, C. M., Alumbaugh, B., Leadbetter, G. W., & Smith, G. A. (2013). Pre-cooling with an ice-slush drink: Effect on core temperature when cycling. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 589.

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This study determined the effect of ingesting an ice-slush drink on reducing core temperature prior to intense cycling in a heated environment. Single-subject analysis methods were used with two elite male cyclists who performed two cycling trials (45-minutes in duration, separated by one week). Each trial consisted of a 15-minute warm-up on a Lode cycle ergometer at 40% of anaerobic threshold power. This was immediately followed by a 30-minute effort at 80% of anaerobic threshold power. Trials were performed in a heat chamber with a controlled temperature of 26.7 to 27.8C. During the 15-minute warm-up, either an ice-slush drink (-4.0 to -2.0C) or a cool liquid beverage (18.0 to 20.0C) was ingested. Total fluid ingestion was 14 g of drink (6.5% solution) per kg of body mass. The beverage was ingested in 14 g increments about five times per minute during the warm-up at a nearly constant ingestion rate. Order of the ice-slush or the cool-liquid trials was randomized. Throughout each trial, core temperature was recorded every 10 seconds. Heart rate, rate of perceived exertion, and heat chamber temperature were recorded every five minutes.

Differences in core temperatures for the two conditions were apparent at five minutes into the warm up and continued to increase throughout the remainder of the trial. Heart rates and ratings of perceived exertion increased similarly during each trial for each condition.

Implication. Pre-cooling the trunk of cyclists through ingestion of an ice-slush mixture resulted in decreased core temperatures during intense 30-minute exercises compared to the temperatures supported by the ingestion of similar volumes of room temperature fluid.

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