I do know that ice cold temp will create an inflammatory effect after a short time, as well, which speeds aging (an extreme example is frostbite - but sub-clinical exposure to ice cold temps could also create an inflammatory response that, while not burning the skin beyond repair, might create inflammation in your system). You will notice this response when you see that your skin becomes warm and red after you remove an ice-cube from it. Well, the same response can occur in your vascular system and your organs. Therefore, I'd shy away from bathing in ice. I would build my tolerance slowly, through room temp showers at first, and then cold showers or cold (not iced) pools/baths later. But that's just me. The pool that I swam in was cold, but not ice cold, and it had a pretty significant effect.