Recovery following a marathon: a comparison of cold water immersion, whole body cryotherapy and a placebo control

CONCLUSION:
The findings show WBC has a negative impact on muscle function, perceptions of soreness and a number of blood parameters compared to CWI, contradicting the suggestion that WBC may be a superior recovery strategy. Further, cryotherapy is no more effective than a placebo intervention at improving functional recovery or perceptions of training stress following a marathon. These findings lend further evidence to suggest that treatment belief and the placebo effect may be largely responsible for the beneficial effects of cryotherapy on recovery following a marathon.

https://www.ncbi.nlm.nih.gov/pubmed/29127510/
I’m shocked, I tell you. Shocked.