From Scientific American:
Mackenzie had wanted to try this procedure, called whole-body cryotherapy, specifically to ease his achy joints. But he says that after receiving multiple two-minute sessions spread out over several days he saw other benefits, too. “I felt refreshed right away. My sleep was better,” he recalls. Soon the treatments became routine: Mackenzie would go four times a week to chill out amid the icy vapors, wearing nothing but his spandex shorts, gloves, socks, slippers and headband to protect against frostbite. Most of his teammates adopted the regimen, too. In fact, there was usually a line for the pod after practice.
Mackenzie and his fellow rugby players are hardly the only devotees of cryotherapy. Star athletes, including Kobe Bryant and LeBron James, have turned to it. Reportedly, Hollywood A-listers such as Daniel Craig and Jennifer Aniston have, too. The market for these devices is beginning to burgeon in the U.S., with sports teams snapping them up to condition their players, and spas and wellness centers installing them for clients looking to relax, lose weight and fight signs of aging. One large U.S. distributor of whole-body cryotherapy machines, Dallas-based CryoUSA, says it has installed more than 200 units across the country since 2011, half of them in 2015. The company expects that the 2016 tally will show an even sharper uptick in sales.
Yet the science behind these devices is decidedly lackluster. In July the U.S. Food and Drug Administration issued a warning stating that there is no evidence these technologies help to ease muscle aches, insomnia or anxiety or provide any other medical benefit. Instead, it said, they may cause frostbite, burns, eye damage or even asphyxiation. In a statement to Scientific American the agency added, “The FDA has not approved or cleared any whole-body cryotherapy devices, and we do not have the …