Novel precooling strategy enhances time trial cycling in the heat

To develop and investigate the efficacy of a new precooling strategy combining external and internal techniques on the performance of a cycling time trial (TT) in a hot and humid environment.

Eleven well-trained male cyclists undertook three trials of a laboratory-based cycling TT simulating the course characteristics of the Beijing Olympic Games event in a controlled hot and humid environment (32°C-35°C at 50%-60% relative humidity). The trials, separated by 3-7 d, were undertaken in a randomized crossover design and consisted of the following: 1) CON-no treatment apart from the ad libitum consumption of cold water (4°C), 2) STD COOL-whole-body immersion in cold (10°C) water for 10 min followed by wearing a cooling jacket, or 3) NEW COOL-combination of consumption of 14 g of ice slurry ("slushie") per kilogram body mass made from a commercial sports drink while applying iced towels.

There was an observable effect on rectal temperature (T(rec)) before the commencement of the TT after both precooling techniques (STD COOL < NEW COOL < CON, P < 0.05), but pacing of the TT resulted in similar T(rec), HR, and RPE throughout the cycling protocol in all trials. NEW COOL was associated with a 3.0% increase in power (approximately 8 W) and a 1.3% improvement in performance time (approximately 1:06 min) compared with the CON trial, with the true likely effects ranging from a trivial to a large benefit. The effect of the STD COOL trial compared with the CON trial was "unclear."

This new precooling strategy represents a practical and effective technique that could be used by athletes in preparation for endurance events undertaken in hot and humid conditions.