I used to work for a Dr doing physical therapy and what you described is actually a therapy called a contrast bath used to treat many injuries. Basically the cold constricts the blood flow and inflammation and the hot increases it. It helps to pump the blood in and out....Its usually used in an isolated area with ice slush and then moist heat, but works as a full body treatment by improving circulation...It will help arthritis and other chronic conditions as well as boost the immune system. It is advised to start and end with cold.....you can do the same thing in a shower if you want, but its much more enjoyabe in the pool/tub. Not only is it very refreshing, it is good for you.....I dont have a pool, but I use the the hose and jump back in the tub.