Last week, the American sprinter Justin Gatlin showed up at the World Outdoor Track and Field Championships in Daegu, South Korea, with frostbite on his feet. This condition was painful — he told reporters that he had blisters on both heels — but it was also improbable, given that he’d developed the frostbite in Florida in August. But Mr. Gatlin had been sampling one of the newest, trendiest innovations in elite athlete training. He’d gone into a whole-body cryotherapy chamber, and his feet had frozen there.
Whole-body cryotherapy is, essentially, ice baths taken to a new and otherworldly level, and it is drawing considerable attention among athletes, both elite and recreational. In the cryotherapy chambers, the ambient temperature is lowered to a numbing minus 110 Celsius or minus 166 Fahrenheit. The chambers were originally intended to treat certain medical conditions, but athletes soon adopted the technology in hopes that supra-subzero temperatures would help them to recover from strenuous workouts more rapidly.
That they would place faith in cold therapy is surprising, given that studies examining the effects of simple ice baths have been, at best, “inconclusive,” said Joseph Costello, a doctoral student in the physical education and sports sciences department at the University of Limerick in Ireland, who is studying the effects of whole-body cryotherapy.
A 2007 study of ice baths found that young men who completed a punishing 90-minute shuttle run and then eased themselves into a frigid bathtub (with the water cooled to 50 degrees Fahrenheit) for 10 minutes reported feeling markedly less sore a few days later than a control group who did not soak. But ice baths did not lower the runners’ levels of creatine kinase, often considered a hallmark of muscle damage. They felt better, but their muscles were almost as damaged as if they hadn’t soaked.
Despite such findings, a growing number of elite soccer players, rugby teams, professional cyclists and track and field athletes in the United States and Europe have eagerly turned to whole-body cryotherapy. Because no agency in the United States or Europe regulates it, it’s impossible to say with any precision how many athletes are currently using the treatment, but researchers like Mr. Costello say the numbers are growing rapidly.
Before entering a cryochamber, users must strip to shorts or a bathing suit, remove all jewelry and don several pairs of gloves, a face mask, a woolly headband and dry socks. Mr. Gatlin neglected that last precaution; his socks were sweaty from a previous workout and froze instantly to his feet. The athletes then move through an acclimatization chamber set to about minus 76 Fahrenheit and from there into the surface-of-the-moon-chilly cryotherapy chamber.
At minus 110 degrees Celsius, whole-body cryotherapy is “colder than any temperature ever experienced or recorded on earth,” Mr. Costello said.
The athletes remain in the chamber for no more than two or three minutes, stamping their feet and waving their arms to retain circulation. A Welsh rugby player described the experience as being in an “evil” sauna, but told British reporters that he believed that the sessions were helping him to recover more quickly from rigorous practices.
The science to support that optimistic appraisal is slim, though. A study by Mr. Costello, published earlier this year in the Scandinavian Journal of Medicine and Science in Sports, found that whole-body cryotherapy did not lessen muscle damage among a group of volunteers who’d completed grueling resistance exercises with their legs before entering the chamber.
Another study, however, published in July in the Public Library of Science One, produced more encouraging results. For it, French researchers recruited a group of trained runners and put them through a simulated 48-minute trail run on a treadmill. The workout was designed to elicit muscle damage and soreness. Afterward, half of the runners entered a whole-body cryotherapy chamber once a day for five days. The rest sat quietly for 30 minutes a day for those five days. Blood was drawn from both groups throughout the experiment.
From the first day onward, the runners who’d entered the chamber showed fewer blood markers of inflammation than the group who had recovered by sitting quietly.
These results suggest that athletes could potentially “save two to three days” of training time compared with forgoing whole-body cryotherapy, François Bieuzen, a professor at the National Institute of Sport, Expertise and Performance in Paris and lead author of the study, wrote in an e-mail. By using the therapy, tired athletes could return to hard training sooner.
But Alan Donnelly, a professor at the University of Limerick and Mr. Costello’s adviser and co-author, is unconvinced. Reducing inflammation, he points out, does not ensure that muscles have recovered. The French researchers did not directly test muscle strength and function after the cryotherapy sessions. So it’s possible that the athletes’ muscles, although less inflamed, were still weak and damaged.
“I just don’t feel that the evidence base for WBC effectiveness is there yet,” Dr. Donnelly said. “If WBC were a clinical treatment or a nutritional aid being put forward for F.D.A. approval, my view is that it would not be approved.”
Such skepticism is not cooling enthusiasm among athletes, however. A cryotherapy chamber that caters to recreational athletes opened in Northern California last month. Its instructional materials caution users to check that all body parts and clothing, including socks, are completely dry before entering the chamber. Frostbite, as Mr. Gatlin discovered, will impede athletic performance. In his signature event, the 100-meter dash, he did not make the finals.
The state Assembly passed the bill in May on a 65-8 vote, but it ran into Senate opposition, including proposed amendments to allow the sale of fins from some shark species that can be legally caught in California.
