Cryosaunas enter the realm of real sports science
Okay, I admit I enjoyed making fun of the “cryosauna” last fall, after it emerged that Alberto Salazar had arranged to have one shipped to New York so that Dathan Ritzenhein could use it before the New York Marathon. With the manufacturer promising “tighter, healthier skin,” “increased libido,” and “stronger, fuller hair,” the concept was ripe for a few jokes — especially since there was no actual science supporting its use for athletes.
But now I have to get serious, because a legit study has been published, funded by the French Ministry of Sports (and not by the manufacturer — actually, it’s a German company that made the cryosaunas used in the study). The full text is freely available via this link. The study had 11 trained runners do a pair of 48-minute hilly treadmill runs (i.e. including enough downhill to trigger muscle damage and soreness) separated by at least three weeks. After one of the runs, they were given three minutes of whole-body cryotherapy at -110 C immediately after, and then again once a day for the next four days. After each cryotherapy session, blood tests were taken to measure a bunch of inflammation and muscle damage markers. After the other run, they followed the same protocol, except replacing the daily bout of cryotherapy with 30 minutes of passive sitting.
One thing to emphasize: this study appears to have been very carefully executed. Throughout the study, the subjects were told exactly how much they were allowed to run, and they weren’t permitted to use anti-inflammatories or other recovery aids. They also controlled food and drink intakes.
The results? They’re pretty complicated because they tested a lot of things. For most of the markers, there was no difference. But there were three key differences:
- C-reactive protein, a marker of muscle damage, stayed almost unchanged in the cryotherapy group, whereas it spiked after 24 hours in the control and was still elevated three days later.
- Interleukin-1beta, a pro-inflammatory cytokine produced after strenuous exercise, was slightly suppressed by cryotherapy (though not by much, if you look at the data below).
- Interleukin-1ra, an anti-inflammatory cytokine inhibitor that counteracts the pro-inflammatory cytokines, was temporarily but significantly enhanced immediately after the post-exercise cryotherapy session.
Here’s what the data for those three factors looked like (WBC is whole-body cryotherapy; PAS is passive recovery):
So does this settle any debate? Well, there’s always a big gap between seeing a minor change in some blood test and translating that to a functional benefit for an athlete. Does cryotherapy permit a better next-day or day-after-tomorrow workout? We don’t really know. On a more general level, do the benefits of (hypothetically) more rapid recovery outweigh the (hypothetical) disadvantages of suppressing the inflammatory signals that tell your body to adapt and get stronger? Again, we don’t really know — that’s still in the realm of coaching art, not science. Is a massively expensive cryosauna any better than a bathtub with a few blocks of ice thrown in? Still don’t know.
But having said all that, this study does suggest that we can move the cryosauna from the category of “wacky techno-schemes that sound like you mail-order them from the back of a comic book” to “serious recovery modalities that are as likely as anything else we currently rely on to work.” (Though I’m still reserving my judgement on the “better hair” claims.)