A recent photo of Adam Craig wearing an ice vest at the start of the hot 2011 Mellow Johnny's Pro XCT race raised some questions about pre-cooling for endurance events. Does pre-cooling really work and are these vests useful and practical?
Use in the Olympic Games
The first time I learned about the concept of pre-cooling the body to improve race performance in hot conditions was in the education seminar series held for coaches and support staff heading to the 2004 Olympic Games. Preparing athletes to successfully complete in heat and humidity was a concern for the 2004 Games and we wanted every advantage covered.
Some members of the 2004 U.S.A. Triathlon Olympic Team did end up using ice vests for pre-cooling before key workouts, before the actual Olympic Games race, after key workouts and after the Olympic race.
What is Pre-cooling?
In past columns I've written about acclimating your body to the heat so you can reduce the negative effects. Acclimatization is the first line of defense to successfully racing in hot and humid conditions. A second or complimentary line of defense is pre-cooling the body's core temperature.
The theory behind pre-cooling is that if you cool your core temperature, you will be able to race for a longer period of time in hot and humid conditions at a higher pace because your cool reserves are greater.
Ice vests, such as the ones used by the 2004 Olympic team members, may be useful, but they are not always practical or convenient for all athletes. The vests cost about $225 and require a freezer for preparation. They also take up more space in luggage and, if the athlete is wearing the vest right up to race start time, there are concerns with keeping track of the vest once it's removed. This is particularly true if the racer is self-supported.
Because of cost, transportation and convenience concerns, we began using ice towels at World Cup races for athletes racing with the International Triathlon Union Sport Development Team. Coaches and support staff could fill a cooler with ice water and transport the cooler to the start line of the race. Towels could be pulled from the ice water and put around the neck and upper back of athletes to pre-cool them while they wait for races to begin in hot environments. Some athletes used towels on their legs as well.
An ice towel on your neck and upper back sounds like a good idea to cool off in the heat, but does it make a difference in your race results?
The Science
Several studies have shown improvements in performance, when racing in hot weather, when the body is pre-cooled. But some of the methods of pre-cooling are not always practical in race situations. A recent study on cyclists showed one method of pre-cooling that is practical and produced positive performance improvements.
The method is a combination of ice towels on the body and ingesting a slushie made with a sports drink before the event. This novel technique improved time trial power output by 3 percent and improved overall performance time by 1.3 percent.