Elite athletes have used this tech for years, and now it’s going mainstream—but does the science back it up?
Ever since Sarah Behrendt, a London-based project director and competitive CrossFit athlete, incorporated palm cooling technology into her running intervals, “everything just feels smoother.”
“It’s easier to relax during the running, which makes it a lot easier to run for a longer period. I also feel that my body is not heating up as much as the interval before when I didn’t use the palm cooling,” says Behrendt, 32, who originally hails from Leipnitz, Germany. She’s one of the early users of the CoreTx Go palm cooling device, a new conditioning aid aimed at combating heat stress, reducing fatigue, facilitating weight loss, and enhancing athletic performance through lowering body temperature. It’s currently available in high-end specialist gyms in London and is now available for individual purchase.
In contrast to whole body cryotherapy—which is a cold therapy that exposes the body to extremely cold dry air, usually between -110°C and -140°C for about 2–5 minutes—palm cooling devices are just for the palms.
Palm cooling devices work by targeting the glabrous tissue, the hairless skin on our palms and soles, which sort of acts like a gatekeeper of external temperature with its huge blood supply, dilating blood vessels to allow for heat loss when temperature rises, and constricting vessels to retain heat when hypothermia kicks in. These technologies have been found to help the body’s core temperature go down, and to affect how the neural signals between the muscle and the brain are transmitted in a way that eliminates perceived fatigue, enabling athletes to complete additional repetitions of an exercise and make increased gains. It is a fine example of cryotherapy, which has been all the rage in the world of elite sports lately. Colin Edgar, founder of the CoreTx Go, says he has been supplying cold therapy solutions like cooled compression or ice baths to elite soccer teams like Manchester United, AC Milan, and Bayern Munich. Cryotherapy is a much-favored therapeutic application among many other titans of the world of sports: Usain Bolt, Cristiano Ronaldo, Justin Gatlin, Kelly Holmes, LeBron James, and Steph Curry are only some of the big names trying to boost their performance and well-being this way. And palm cooling in particular, has attracted the attention of researchers at Stanford University.
It only took participants three weeks to increase their bench press work volume by 40%.
In a paper that was published in the Journal of Strength and Conditioning Research in 2012, Stanford scientists had participants insert their hands into a glove with the palm placed on a cool pad for three minutes between sets of bench press or pull-up exercises. The pad had cold liquid circulating through it and was pressurized to stimulate additional blood to flow through the hands. The research went on for multiple successive weeks and involved biweekly workouts, but it only took participants three weeks to increase their bench press work volume by 40 percent. Six weeks into the training, pull-up seasoned athletes (people who could do at least 10 pull-ups—often between 15 and 20—in two minutes) had increased the number of pull-ups by a whopping 144 percent, while novice pull-uppers had upped their own volume by an also-impressive 80 percent.
Today, the palm cooler need not wear a glove. The modern process involves adding deionized water into a unit that looks like an old cassette player, connecting two hoses and cooling cups, pre-chilling to the desired temperature, and holding the hoses firmly for 90–120 seconds as they circulate the chilled water over your palms.
“I was very skeptical of the technology in the beginning, but the results I see both in myself and my clients have been remarkable,” says Matt Lawrence, a sports physiotherapist and owner of CrossFit 2012, a studio club in London and one of the few select high-end sports clubs where the palm cooling tech is currently available. “As you move between sets, you get tired. By using palm cooling you can maintain your repetitions from set one to set two to set three,” says Lawrence. There will be a slight decline, maybe only one or two repetitions. “And as the total number of repetitions performed is higher per set, you’re looking at an overall workload that is significantly higher,” says Lawrence.
But none of this is new, since those Stanford scientists trumpeted their palm cooling glove as “better than steroids” more than 10 years ago. So why did it take so long for this technology to reach the masses?
An athlete’s secret
According to the CoreTX Go people, the reason we haven’t heard of it before is that these types of performance-enhancing strategies are closely guarded by elite athletes, as they want to maintain their advantage over others. “In the U.S., NFL football clubs have been using palm cooling, and the military also,” Lawrence says. In the U.K., CoreTX Go recently partnered with the Belfast Giants, a leading ice hockey team and current British champions.
According to CoreTX Go, the cost of the device for consumers starts around £2,500 ($2,993). Asked about the hefty price tag, a company spokesperson said it’s in line with market prices for commercial-grade, performance-enhancing equipment. Ground-breaking tech is considered a great investment, they said in a statement to proto.life.
“It is true that for centuries athletes have tried to find ways to improve their sports or exercise performance beyond what someone can get from just training,” says Claudio Gil Araújo, director of research and education at the Brazilian Exercise Medicine Clinic in Rio de Janeiro. The drive needed to sustain dominance in the world of professional sports is not unique to our times—where the difference between first place glory and lucrative contracts and second place may be a matter of split seconds.
Ancient Greek Olympians ate sheep’s testicles, which are full of minerals and protein and can contribute to an increase in testosterone, while Roman gladiators at the Colosseum consumed strychnine, which, in small doses, can strengthen muscle contractions and stimulate the heart, to disguise their pain and fight like lions. This extra “alternative” something goes with the territory in competitive sports—and maybe always has. “Yet, often these approaches fail to have a minimal scientific reasoning and are no more than placebo effect, while they may even cause serious damage,’’ Araújo says. It’s not that top athletes have not shown an affinity for superstition anyway: Tennis legend Björn Borg would grow a beard and wear the same Fila shirt before each annual tournament. Dallas Mavericks shooting guard Jason Terry slept in the shorts of the opposing team the night before each game. Former New York Mets reliever Turk Wendell chewed black licorice before pitching, and UFC Light Heavyweight Champion Lyoto Machida drank his own urine every morning.
That said, palm cooling does have some scientific rationale, continues the Brazilian researcher. “We know that body temperature plays a role in the development of overall fatigue through the central nervous system. Cooling your hands might—to a certain extent—postpone [triggering] the ‘limiting-fatigue’ brain’s safety mechanism,” he says. This mechanism affects fatigue in three ways: it reduces both core temp and the temperature of activated muscles, and it impacts the fatigue signals to and from the brain. As perceived exertion and performance are highly affected by temperature, palm cooling helps increase overall workload.
In addition, cooling your palms might fine tune your body’s sympathetic activity—the maze of nerves that controls your “fight-or-flight” response. “Sympathetic stimulation is also known to boost our exercise performance as well as our tolerance to stressful situations,” Araújo says. However, he remains skeptical of every attempt to manipulate the natural workings of the body until strong evidence convinces him otherwise.
“History has shown that several attempts to fool physiological sensors and established mechanisms in order to improve exercise tolerance have failed dramatically,” he says. In the mid-70s, American swimmers practiced “hypoxic training” or holding their breath for several seconds while swimming in an attempt to challenge the body’s physiological sensors and to obtain higher tolerance to a low oxygen content in the blood, thus (theoretically) benefiting sports performance. “However, subsequent research studies showed that this approach was inducing hypercapnia, which is an increase in carbon dioxide in the blood and often headache, rather than true hypoxia and no significant performance benefits were found,” Araújo says.
Additionally, for some years, marathon runners used low compression socks to increase the blood flowing back to the heart (the venous return) without hampering the blood flowing away from the heart and to the legs (the arterial flow). “So far, most of the research failed to show significant or true performance benefits or better exercise tolerance in those that decided to apply this strategy,” Araújo says.
Regardless of what the future has in store for chilling your palms, Behrendt says she’s planning on using the technology much more to ramp up her workouts now that she has got the hang of it. “Especially now with CrossFit open around the corner, I am approaching the intensity phase of my training. After palm cooling, I always feel more refreshed and ready to go,” she says. Experts like Araújo say that more high-level research by different groups needs to be done to back up the claims of palm cooling devices, but for those who swear by them, like Behrendt, cold hands are the way to go.
Editor’s note: This article was updated on 3/7/23 to clarify the attribution in the tenth paragraph.