Crushed ice before events in hot/humid conditions may help performance

The IntroductionIced slurry drink

Pre-cooling in an ice bath, air conditioning, or wearing an ice vest has consistently been shown to benefit performance in endurance events in the heat. However, these strategies require equipment, logistical problems and make us uncomfortable before events. This recent research has used ice crushed up in a blender as a way to cool the body down. The question was asked, will it also help endurance performance in the heat? The results say yes!

 

The Research

Seven endurance-trained male cyclists and triathletes (27.7±3.1 years; 81.4±9.1 kg)  completed two 40 km cycling time trials in a climate chamber (300C, 75% humidity) preceded by 30 minutes of either crushed ice ingestion (ice mixed in a blender and 1.40C) or normal tap water (260C) consumption amounting to 6.8 grams per kilogram of body weight. During the 40 k cycling time trial, gut (measured using a pill that transmits gut temperature) and skin temperatures, cycling time, power output, heart rate, blood lactate, ratings of perceived exertion and thermal sensation were measured at set intervals with the athletes consuming tap water at regular intervals throughout the test.

The Results

Pre-cooling lowered the core body temperature after ice ingestion significantly more than in the control condition (36.7±0.70C vs 37.3±0.20C). This difference remained evident until about a sixth of the way through the time trial was completed on the bike. No significant differences existed between conditions at any time point for skin temperature, rating of perceived exertion, or heart rate. Crucially, the cycling time trial completion time was 6.5% faster in the ice ingestion when compared with the normal water condition (Ice: 5011±810 seconds, Water: 5359±820 seconds).

The So What?

Crushed ice ingestion was effective in lowering body temperature and improving subsequent 40-km cycling time trial performance. This strongly suggest that when about to do an event in the heat, consider having a slurrried ice drink before you race. I couldn’t see any reason why a sports drink slurry couldn’t do the same thing.

 

Ihsan, M., Landers, G., Brearley, M. and Peeling, P. (2010) Beneficial effects of ice ingestion as a precooling strategy on 40-km cycling time-trial performance. International  Journal of Sports Physiology and Performance. 5(2): 140-51.