The Hype Behind Stanford’s Magic “Cooling Glove” for Athletes

What's to come?
Sept. 7 2012 2:26 PM

Better Than Steroids?

The hype behind Stanford’s magic “cooling glove” for athletes.

The Magical Cooling Glove.
The magic cooling glove

Screengrab courtesy Steve Fyffe/Stanford University.

Researchers at Stanford have figured out a way to boost athletic performance that's "better than steroids" and totally safe. It's called the cooling glove, and it controls the body's temperature through the palm of the hand. We're most efficient at shedding heat through the hairless (or glabrous) skin on our faces and extremities, where blood vessels congregate at shallow depths. So biologists H. Craig Heller and Dennis Grahn thought to speed up that process by attaching a gentle vacuum and a water pump to an airtight mitt. The negative pressure causes the vessels of the hand to dilate, drawing warm blood from the body's core. Then the circulating water cools the blood. Since our muscles start to falter when we get too hot, a glove like this could make your workout longer and more productive.

Daniel Engber Daniel Engber

Daniel Engber is a columnist for Slate

At least that's what a Stanford press release announced last week, and what was repeated in due course on Kottke ("I expect this will be either everywhere in pro sports in a couple of years or banned"), on Gizmodo ("the implication for sports … could be huge"), and elsewhere on the Internet. Professors have figured out a way to "reset a temperature-sensitive enzyme" in our muscles—they've made a magic glove that gives us super strength! Goodbye anabolic steroids, hello gauntlets of power!

What seems like a cool idea today was just as exciting back in 2008, when the vacuum mitt was touted as a "new invention." For that go-round of publicity, Heller cited data showing that a glove-wearing subject in his lab had gone from doing 180 pull-ups in a session to more than 600 in six weeks' time. That's the same statistic that showed up in last week's press release—"he went from doing 180 pull-ups total to over 620," said Heller—as well as in another Stanford story from 2004: "We helped a weight-lifter increase his capacity to do pull-ups from 180 to 600 in the same time period after six weeks of training. Our technology would certainly give athletes a clear competitive edge."

In fact, one can trace this repetitious enthusiasm for the cooling glove—for this "new" invention—all the way back to 2002, when the BBC reported on its amazing effects and the New York Times called it one of the year's best ideas. Heller and Grahn's startup firm—a company called AVAcore Technologies—had just released the first commercial version of their device, a $3,000, water-cooled vacuum bubble with a battery, and announced that the San Francisco 49ers were using it in practice. But the idea dates back further: The professors founded AVAcore in 2000, around the time they filed for a patent, and they were tinkering with the concept for many years before that, too.

All of which makes you wonder. It's been at least 15 years since these guys started building prototypes and a decade since their product first hit the market. So why is the magic glove still getting play? And does it really work?

It turns out that Stanford owns a portion of the glove—a percentage on the deal to license the technology—so if AVAcore makes a fortune, then both the professors and the school cash out. By touting the "latest" data from Grahn and Heller's lab—some of which has been sitting around for 10 years or more—Stanford sets the stage for a new iteration of the product, one that's in development but not yet available for purchase. It's no different from the original in its basic concept, but has a sleeker form factor and may end up cooling more efficiently. Grahn told me that the recent coverage wasn't planned to coincide with a product relaunch, but he hoped the company could find a way to tap the current "groundswell" of interest.

The press release that sparked the most recent wave of glove-love overlaps instead with a paper in this month's issue of the Journal of Strength and Conditioning Research. At long last, we’re seeing the data from that guy who did 600 pull-ups so many years ago. "We finally got it written up," says Grahn. The study, which aggregates results from a decade's worth of experiments, found that "palm cooling" helped people do 144 percent more pull-ups than they did before, on average. A closer look reveals that the effect might not be so beefy as it looks, however. That figure comes from testing just a handful of people in the lab—even after 10 years of research—and it has some honking error bars (+/-83 percent). To put it in perspective: Before the palm-cooled training, their scores ranged from 70 to 153 pull-ups in each session; after training, they ranged from 70 to 616.

Other data from Grahn and Heller's lab confirm the benefits of the technology, at least under the right conditions. For one experiment, members of the Stanford football team did sprints across a football field between bouts of resting unassisted or with their hands in cooling gloves. When it was mild out, 72 degrees, the gloves did little to improve performance. But on a 95-degree day, they helped to mitigate fatigue: Players would run farther down the field before each whistle.

That may not sound surprising to anyone who's ever played a sport in summer and stopped to splash some water in his face. The face, after all, includes another glabrous surface of the body, so cooling it with water might help stave off exhaustion. But there are other ways to cool down: An overheated athlete might sit next to a mister or dip her hands into a bucket of water. Other research teams have tried to cool the large muscles of the arms and legs, before or after workouts, to enhance performance. We might expect that any of these approaches would help performance on the field or at the gym.

That's not the same as saying they would all be equally effective. To find out which method of cooling works best, we might like to see the magic glove go head-to-head against some other methodologies—including the splash of water in the face. But much of the work from Grahn and Heller's lab has omitted any such comparisons. One study set the vacuum glove against the use of cooling pads on the thigh, the back and the abdomen, while subjects rode a treadmill. The data showed a modest, relative benefit for the device, in terms of keeping heart rates down—but a cooling pad placed along the upper back seemed to do about as well.

Meanwhile, a pair of studies done in other labs has come up with negative results for the gloves. In 2008, the Air Force Research Laboratory reported the results of a run-and-rest experiment, not unlike the one Grahn and Heller did with the Stanford football team. They compared the AVAcore device to a refrigerated gel pack and found that neither improved performance over a control condition, in which subjects were left to recover on their own. The authors concluded that the Stanford glove was "ineffective at improving performance" and called for a stop to further research on the matter.

Grahn and Heller point out that the Air Force study was so mild in its demands—subjects only had to sprint for 30 seconds at a time—that the benefits of cooling would be invisible. It's true the subjects showed little sign of flagging in the heat. But a group at the University of New Mexico followed up two years later with a more exhaustive task. Subjects wearing body armor and heavy backpacks were made to walk a treadmill in a 108-degree room, with breaks for cooling and rehydration. In this one, the AVAcore glove went up against a standard water bath (used for dipping of the hands) and an Army cooling vest that pumps water around the torso. The glove and water bath proved ineffective; only the vest increased endurance.

But that test might have been too difficult, says Grahn. An earlier study from the Stanford lab had shown that the glove's effects diminish as a workout gets more intense. If the Air Force test was too easy, then the New Mexico test was too hard. Another problem, says Grahn, is that both studies looked at the original AVAcore, which suffered from a poor design. To make it work, subjects must grip a cone inside the glove, which could serve to squeeze the blood right out of their palms. The newer version might perform better, he argues.

In any case, Grahn told me, a few negative results don't amount to very much in science. "Anyone can show that something doesn't work," he says. "That's an easy thing to do." So why don't Grahn and Heller run their own versions of this test and see how their device stacks up against some other forms of cooling? Could it be they'd get the same performance-enhancing effect—better than steroids, totally safe—from dunking someone's hand in a bucket of water? "If you can find the right temperature for the water," says Grahn, "if you can do this, that, and the other thing—then yes, you can make it work. I won't argue with that. … But we're making a very efficient, portable bucket."

After a decade's worth of recycled data and overheated coverage, there's no sign that Grahn and Heller's $3,000 bucket has changed the face of professional sports, nor that it ever will. Sure, magic gloves are nice, but it might be time to splash some water on the hype.