In the spirit of summer and pools and swimming, a quick little physiology lesson, since I just finished my exercise physiology and autonomic nervous system studies. Ever curious why you’re supposed to wait an hour after eating before you jump in the pool? When you start exercising, your body reroutes blood from your digestive system (which is activated by eating food) to your muscles. It clamps off a lot of your circulation from your stomach to the muscles you’re using. And when your digestive system still has food in it that it’s trying to digest, it needs blood flow to get the energy to digest it all. It’s not getting that flow, so it keeps working, without oxygen, and you get acid buildup because of it. And voila. Acid buildup equals pain, pain equals cramp.