Icebaths have been used by cyclists and athletes for a quite some time as a recovery method. The idea is: cycling between warm and cold environments creates a repeated constriction and dilation of blood vessels which ends up being like a pumping motion that bonfies the body's normal circulation.  Ice baths are performed to encourage bloodflow, help eliminate metabolic waste and essentially improve recovery after exercise. I've used this method during particular periods of my cycling career.   The Wim Hof Method , which also incorporates cold water exposure into its teaching...