Sunday, July 7, 2002
By Janet Rae Brooks
The Salt Lake Tribune
Dogs pant to cool themselves. Elephants radiate heat through their ears. Humans sweat.
At least, that's what the textbooks have been telling us.
Now, two California researchers are challenging the accepted wisdom that sweating is the defense of choice for overheated humans with data showing that significant cooling takes place through special blood vessels in the palms of the hands.
Using a specially developed machine, the Stanford University scientists found that as much heat could be extracted from the palm of one hand as across the entire body during maximal sweating.
"It's making us rethink how our bodies cool themselves," said Andy Subudhi, an exercise physiologist at The Orthopedic Specialty Hospital's Institute for Sports Science and Medicine in Murray, where a prototype of the machine is being tested.
More effective cooling would allow athletes to train harder, recover faster and avoid potentially lethal overheating.
Although testing of the new RTX technology -- for Rapid Thermal Exchange -- is focused on athletes, others who work in the heat such as firefighters and miners could also benefit. So could soldiers clad in biological warfare suits or pilots waiting in hot planes to take off from aircraft carriers.
Those suffering from chronic diseases that are exacerbated by heat, such as multiple sclerosis, could also make use of the cooling technology. Heart-attack and stroke sufferers could be cooled to reduce tissue damage. By reversing the process, cancer patients could be warmed to enhance the effects of chemotherapy.
Several NFL teams have leased prototypes of the heat-extraction machine to use at minicamps and training camps this summer. As the technology shrinks, the device could be mounted on a bicycle, tucked in a glove or eventually fit into a marathoner's training shoes or a soldier's boots.
The workings of the RTX machine, patented through Stanford, are housed in a blue box about the size of a cooler. A tube extending from the box sends cool water to a metal plate inside a clear plastic bubble, where subjects place their hands.
Like elephants' ears or dogs' tongues, human palms contain "radiators" where blood is pumped when core temperature increases. The RTX technology capitalizes on this natural cooling mechanism by introducing a slight vacuum and particular temperature settings to the metal plate.
A second tube removes water heated by the warm blood, while a third tube produces the vacuum.
In a small pilot study, RTX inventors Dennis Grahn and Craig Heller, Stanford animal physiologists, had subjects pedal to exhaustion in a "hot" room wearing two sets of long underwear, plastic rainsuits and hooded sweatshirts. After the subjects' temperatures rose to an average of 102 degrees, they stuck one hand in the RTX machine. Their body temperatures dropped to normal range within 15 minutes.
When subjects cooled on their own in the same conditions, core temperatures remained elevated for 30 minutes.
"The difference was phenomenal," said Craig Coombs, vice president of Human Studies for AVAcore Technologies, the Palo Alto, Calif., company marketing the RTX technology. "You still feel hot because you don't have any thermo-sensors inside your body, but you feel totally refreshed."
In other small-scale trials, the researchers also found that athletes who used RTX between sets while weight training made impressive strength gains. Subjects who rode stationary bikes while using RTX were able to pedal up to 40 percent more and recovered more quickly.
Although the technology is simple, the machine has produced some convincing data, said Subudhi. "If you look at the difference between cooling yourself in an air-conditioned room or in this machine, this will cool you much more effectively," he said.
The studies, however, will need to be repeated on larger populations, he said. And to gain wide acceptance for the RTX machine, AVAcore Technologies must be able to explain how it cools so fast and to advise coaches and athletes how to use it during training and competition.
Should athletes be pre-cooled before their workouts? If used between bouts of exercise, or during games, for how long should the machine be used? At what temperature settings? Does using RTX truly aid recovery and allow athletes to work harder? Does using RTX prevent athletes from acclimatizing to the heat on their own? Could athletes become reliant on the technology?
"There's so many questions," said Subudhi.
© Copyright 2002, The Salt Lake Tribune