http://www.jsonline.com/sports/packe...357455321.html

"I'm stimulating the body's fight-or-flight response by stimulating those skin receptors with that extreme cold," Shields said. "The body is fooled into thinking it's in danger.

"Being in danger is forcing all the blood out of the extremities to the core, which makes it very nutrient-dense and oxygen-dense. Then when you come out you get hypovascular dilation, all those veins just go boom — huge endorphin rush and your brain is stimulated to heal after that for up to 36 hours."