Cryotherapy chambers: the evidence still isn't there

Recovery strategies are widely used with the intention of preventing or minimising muscle soreness after exercise, and whole-body cryotherapy has been actively promoted as one of the most effective. The protocol involves single or repeated exposures to extremely cold dry air, below -100 °C, in a specialised chamber or cabin for two to four minutes at a time. That is an expensive and physiologically extreme intervention, so the standard of evidence behind it matters. This review set out to assess both the benefits and the harms in adults.

The reviewers searched multiple databases, trial registers, conference proceedings and reference lists, and contacted experts, with searches run in August 2015. They sought randomised and quasi-randomised trials comparing whole-body cryotherapy with passive control or with active alternatives such as cold or contrast water immersion, active recovery or infrared therapy. Prespecified primary outcomes were muscle soreness, subjective recovery such as tiredness and well-being, and adverse effects. Four laboratory-based randomised trials were included, reporting on 64 physically active adults of mean age 23, all but four of them male: two parallel-group trials with 44 participants and two cross-over trials with 20. Evidence quality was graded with GRADE.

All four trials compared cryotherapy with rest or no cryotherapy. Very low quality evidence showed lower self-reported soreness at rest one hour afterwards (SMD -0.77, 95% CI -1.42 to -0.12; 20 participants), but at 24 hours (SMD -0.57, 95% CI -1.48 to 0.33), 48 hours (SMD -0.58, 95% CI -1.37 to 0.21) and 72 hours (SMD -0.65, 95% CI -2.54 to 1.24) the intervals also included no between-group difference or a benefit favouring control. One nine-participant cross-over trial found no difference in tiredness but better well-being at 24 hours. Against far-infrared therapy, one trial in nine well-trained runners found less soreness at one hour but not at 24 or 48 hours. No trial reported active surveillance of adverse events.

This review complicates the marketing around cryotherapy chambers rather than disproving them: the direction of the soreness estimates leaned favourable, but the imprecision and high risk of bias mean nothing can be concluded. No included study compared cryotherapy with cold water immersion or tested different durations and dosages, so the head-to-head questions people actually ask remain unanswered. There is also no evidence at all in women or in elite athletes, the groups most often pictured using it. The absence of adverse event surveillance is a substantive gap given the temperatures involved.

The take-home is about certainty rather than a verdict: on this evidence there is no reliable basis for expecting whole-body cryotherapy to reduce soreness or improve how recovered you feel compared with resting. Any impression of benefit in the pooled data was fragile, short-lived and drawn from very few, mostly male, young participants. Safety was not formally tracked, which is worth knowing about an exposure to air below -100 °C. Higher-quality trials with proper adverse event reporting are what would change the picture.