When people exercise, their muscles consume energy and generate heat as a byproduct. When enough heat accumulates internally, it can limit exercise performance. Two Stanford biologists have developed a method for cooling that maximizes heat transfer through the palms of the hands. The idea is to engorge confluences of arteries and veins located there by mechanically drawing blood into them. The technology was used by some athletes during training for the Olympic Games in Athens, and it may soon find its way into attire for military personnel and others who work in extreme heat.

"We literally cool the body from the inside out, rather than from the outside in, which is the conventional method," explains Senior Research Scientist Dennis Grahn, who developed the cooling device with H. Craig Heller, the Lorry I. Lokey/Business Wire Professor in Human Biology and Environmental Biology.

The device works by creating a local subatmospheric pressure environment, Grahn says. "We stick the hand in a rigid chamber with an airtight seal around the wrist, and then we draw a bit of the air out of the chamber," he explains. "This causes blood to be pulled into the hand. Then we cool the overlying skin surface of the palm of the hand [by circulating cool water through a closed system on which the palm of the hand rests], which cools the blood in the hand's vascular heat-exchange structures. Arteries deliver blood directly from the heart to these vascular structures, and veins then carry the blood from these structures back to the heart."

Grahn and Heller, animal physiologists who specialize in temperature regulation, originally set out to devise a way to eliminate the violent tremors many patients have when they come out of anesthesia after surgery. From studies in rats, the researchers determined that such tremors occur because the body's temperature regulation mechanisms are suppressed during anesthesia. They reasoned that rapid rewarming might stop
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Contact: Dawn Levy
dawnlevy@stanford.edu
650-725-1944
Stanford University
4-Oct-2004

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