Sure, icing your wrists can help you cool down more easily — but could chilling your palms help you lose weight and stay in shape?
A small study being presented at the American Heart Association's Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2012 Scientific Sessions used palm cooling to help obese women exercise, and noted that not only did they stay with the exercise longer, but saw better improvements.
Top image: Stabil on Flickr.
The researchers actually used an expensive piece of sports equipment for the study, but a chilled water bottle would also help. This device circulated temperature controlled water past their hands, while using a slight vacuum to keep their arteriovenous anastomoses blood vessels open to assist cooling. Half the group of obese women worked out using the device with water at 60.8°F, and half at 98.6°F. Put through a series of exercises designed to gradually work up to 80% maximum heart rate for 45 minutes, those with warm water dropped out of the process earlier. The women using the cool solution saw an average improvement of five minutes off the time to walk 1.5 miles, lost an average of three inches off their waists, and had lower resting blood pressure.
The study's leader Dr. Stacy Sims suggested the reason for the difference was it might "help exercisers feel cooler, less sweaty and less fatigued — allowing them to work out longer and make them more likely to stick with their exercise regimen."
My concern with this study is that the one group of women were holding a tube of body temperature water in their palms — essentially negating the inherent air cooling properties of one's hands. During exercise, humans thermoregulate primarily through evaporation, and this effectively blocks off that method for part of the body, which might make the exercisers feel even worse about what they're doing.
Still, it certainly wouldn't hurt to run with a cold water bottle in hand while trying to get back in shape for summer.
UPDATE: Updated to clarify some information, and Dr Sims corrected me on my lack of knowledge about human cooling:
The frozen bottle is a combination of holding the bottle for cooling perception but the effective means of cooling is drinking the icy cold water as it melts.
Evaporative cooling doesn't occur on the non-hairy surfaces of the body (i.e. palms of hands and soles of feet)- so the body temperature water circulating under the metal plate of the glove did not hinder evaporative cooling or other thermal sensitivities- if anything, there was slight cooling due to the temperature gradient change of body temperature going up but water temperature staying at the 98'F