The use of cryotherapy (the application of low temperatures in medical therapy) is often touted as an established effective method when treating acute soft tissue injuries. Research from the past five decades suggests that the application of cold therapy relaxes muscles, reduces inflammation, increases pain threshold, increases blood flow and the list goes on.
(However, it is worth noting that there are some meta-studies that suggest there is no good empirical justification for the claimed benefits of general cryotherapy; the authors claim there is insufficient number of high quality randomized controlled trials that would allow us to reach a firm conclusion).
One particular form of cryotherapy, Whole-Body Cryochamber (WBC), has been gaining much traction and acceptance within the sports world. Essentially, it is a big freezer you walk into for about two minutes or so. Although one can easily find online, as expected, exaggerated benefits and pseudoscientific explanations of the mechanisms underlying those benefits; nevertheless, the scientific literature does seem to suggest that the whole body cryochamber is somewhat beneficial in particular cases.
But the evidence is fairly limited and most has yet to be reproduced. When WBC was compared to traditional ice bath or localized cryotherapy, there were no greater benefits found. Contrary to what is often proposed. In another study, they found that even though WBC got skin cooler, it did not get the skin cold enough to achieve pain relief. As recently as July of 2016, the FDA concluded that after a review of the existent medical literature, they found very little evidence for its [WBC] effectiveness on treating the conditions that its proponents promote.
In a more robust meta-analysis review done by Bleakley et al. and Costello et al., like the FDA, concluded that there is very little evidence that it is in fact effective.