Ice vest keeps runners cooler in the heat

By Anne Harding

NEW YORK (Reuters Health) - Long-distance runners who wear an ice vest while warming before a race stay cooler during competition in hot, humid weather, a new study shows.

The investigators found that runners who wore an ice vest during warm-ups had an average body temperature increase of 35.82 degrees Fahrenheit after finishing a 4- or 5-kilometer race, compared with an average increase of 36.95 degrees F among athletes who didn't use the vest.

Such small temperature differences may make a difference in performance for elite competitors, but would have little effect for recreational athletes, Dr. Iain Hunter of Brigham University in Provo, Utah, told Reuters Health. Nevertheless, he added, the vests could useful for runners -- elite or otherwise -- who find exercising in very hot, humid weather particularly tough.

The ice vest may also help anyone who is susceptible to heat injury or heat illness, Hunter said. "If there's some concern about someone that has the tendency to get overheated, that might be the person that it would be geared towards," he added.

Hunter and his team tested prototype ice vests made by Nike, which had been used by Australian and US athletes during the Athens Olympics in 2004. The study included 18 National Collegiate Athletic Association Division 1 cross-country runners, competing in a 4-k race in Hawaii or a 5-k in North Carolina. The athletes, all women, swallowed temperature sensors 4 hours before the race.

Half of the women put on the ice vest 1 hour before the race began, and the other half put on a regular T shirt. All of the runners were told to warm-up in the usual matter.

The athletes kept the vets on until 1 minute before the race began. At the end of the race, the difference persisted, with a 33.13-degree F difference in temperature increase between the two groups.

The study's size was too small to show whether the cooler runners were faster, Hunter noted, although he and his colleagues point out that some studies have found benefits for pre-cooling for endurance runners.

Nike custom-makes its Ice-Vest for competitive athletes as part of sponsorship deals, Hunter added, but the vests are not currently commercially available.

While there are other ice vests on the market, Hunter said, "There's not one out there that's really a good price and that's comfortable to wear and covers the body completely."

SOURCE: Journal of Athletic Training, October-December 2006.