Ice baths are based on cryotherapy - removing heat from certain areas of the body. It is a technique that is used in many areas of human health, including prostate cancer treatment - although in prostate cancer treatment the therapy is used to actually freeze off cancerous tissue in the prostate so that they die. Cryotherapy after exercising is used to limit muscle damage and encourage fast recovery times.
Initially ice baths became famous for use after a tough exercise session, but research suggests it can be used prior to an exercise session in order to boost performance.
 Mayo Clinic, Prostate Cancer (www.mayoclinic.com/health/cryothe ...)
 Skeim M. et al. Self-paced intermittent-sprint performance and pacing strategies following respective pre-cooling and heating. European Journal of Applied Physiology
2011, Pages 1-14