Cooling the palms of the hands while working out helped obese women exercise longer, reports researcher Stacy Sims, a research scientist and exercise physiologist at Stanford University School of Medicine.
"If you think about adipose [fat] tissue, it’s a great insulator," Sims said. For people who are obese, that means they often get too hot while exercising.
"It would be like Lance Armstrong wearing a wet suit for the entire Tour de France," she said. "We’re trying to address those barriers."
Sims wanted to see if cooling off the hands of the women she studied might help them overcome fatigue and overheating while exercising.
The device she used is already in use by some professional athletes, according to Sims who decided to test it on obese women, who she finds often abandon working out due to overheating and fatigue.
In the study, Sims evaluated 24 healthy women, aged 30 to 45. None had exercised long-term in the past. They were obese, with a body-mass index (BMI) of between 30 and nearly 35. (BMI is a measure of body weight in proportion to height, and obesity begins at a BMI of 30).
She assigned the women to one of two groups: both held the cooling device in their palms, but only one group had cool water running through the device; the other had water that was body temperature running through the device.
Both groups participated in three exercise sessions a week for 12 weeks. Each session included 10 minutes of body weight exercises, 25 minutes to 45 minutes of treadmill walking with the cooling device and 10 minutes of core-strengthening exercise. They worked up to the time they could handle on the treadmill.
On the first day and last day of the study, the women did a 1.5-mile walk that was timed.
The cooling group shaved more than five minutes off their time for the 1.5 mile treadmill test. They averaged 31.6 minutes at the start and 24.6 minutes at the end.
Their exercising heart rate went up, too, 136 beats per minute to 154 beats per minute — a good thing.
The cooling group also took more than two inches off their waist by end of the 12-week study. That improves not only appearance, but health, since big waists are linked with heart disease. Their blood pressure also went down, from 139/84 to 124/70. (Below 120/80 is the goal.)
In contrast, the comparison group didn’t show any substantial differences in any of the measures, Sims found.
The cooling group also stuck with it more, Sims said. “The controls dropped out early, and skipped a lot of sessions,” Sims noted.
The cooling group seemed to get into the regimen, she said. “At the end, some women were running [on the treadmill],” she said.
"If you reduce the heat stress, you reduce fatigue, sweating and discomfort," she explained. "You reduce a lot of the physiological barriers that [make] people say, ‘I don’t want to continue.’"
The finding that the comparison group had no substantial effects after 12 weeks “is a bit strange,” said Duck-chul Lee, a physical activity epidemiologist at the Arnold School of Public Health.
He added that “the results may not apply to people exercising in a cold condition, for example, outside in winter.”
Sims wants to do a study of the device with more people. Meanwhile, she says, it won’t hurt to try it at home: "Take a water bottle, freeze it and take that with you in your bare palm [as you work out]. As it melts you drink the cool water. It’s worth a try."