As odd as that may sound, Craig Heller, PhD, Dennis Grahn, PhD, and their lab have been using the technique to improve athletic performance for 15 years now, and today, they’re looking to use similar techniques to treat hyperthermia, improve quality of life for people with multiple sclerosis and better manage surgical patients’ temperature during and after their time in the operating room.
Heller, a professor of biology and a member of Stanford Bio-X, says none of that would have happened had it not been for the problem of cold patients in the recovery room falling into their laps. A physician friend explained to Heller and Grahn, hypothermic patients coming out of anesthesia could take hours to rewarm, and posed a management problem for nurses.
Heller and Grahn, experts on mammalian temperature regulation, came up with a simple idea: draw blood into a patient’s arm with a slight vacuum, heat the arm, and the warm blood would return the body core. They built an air-tight sleeve outfitted with a water-perfused pad surrounding the arm and a vacuum pump to create negative pressure in the sleeve to increase blood flow to the arm.
The idea worked and led to the discovery that when special gated blood vessels in the palms of the hands open, they enable blood to bypass high-resistance capillaries and flow into a network of larger, low-resistance veins that function as heat exchangers. That system, Heller explains, is only found in non-hairy skin.
“Most mammals have fur, so they can only dissipate heat from their non-hairy skin,” Heller says. “We don’t have fur, but we have inherited the same specialized heat loss blood vessels.” In essence, the non-hairy skin of the palms of our hands, soles of our feet, and the upper part of our face where we blush, are natural radiators that cool the body. In rewarming patients, the team was using them in reverse of their normal function.
The team turned to exploiting these natural heat exchangers to treat overheated subjects resulting in the discovery that extraction of heat from the body could improve athletic performance. Early tests with a gym-frequenting research assistant, Vinh Cao, showed that cooling his palms in between sets of pull-ups increased the total number of pull-ups he could do in a single workout of 10 sets interspersed with 3 minute rests to more than 600 over a six-week conditioning routine.
The team also found cooling improved endurance during cardiovascular exercise, with lasting effects on strength and endurance. The cooling glove is now used by Stanford athletic teams and professional athletic teams in the U.S. and elsewhere, Heller says.
Most recently, with funding from the Pac-12 athletic conference, the lab has been testing the technique in women — most previous work had been done only on men — with similar results. “We’ve actually had some freshmen women doing over 800 push-ups” in under an hour, Heller says.
There are myriad other applications including improvement of quality of life for patients with multiple sclerosis, whose symptoms often get worse in hot weather or with a slight rise in body temperatures. Some MS patients homebound in summer were able to return to playing golf and engaging in other activities in warm weather, Heller says.
The team has also built a wearable cooling system for military working dogs and a similar, Camelback-sized system for humans. “We first got motivated to do that by email communications from Ebola workers in Sierra Leone,” where hot temperatures and protective equipment combine to make overheating a serious problem. Such devices could also help many others who work in hot conditions such as firefighters, military personnel, farm workers, and industrial workers.
Previously: To dissolve mysteries of the cytoskeleton, Stanford researchers create new tool and Fits like a glove: Stanford researchers develop medical applications for the Cooling Glove
Photo of Dennis Grahn with student research assistant Riasoya Jodah by L.A. Cicero