Stomach Cramping
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.
Actually, the topic of stomach cramps is quite contentious: http://www.snopes.com/spoons/oldwives/hourwait.htm
The advice about swimming and eating IIRC was taken from a very old edition of a swimming safety manual which has since been debunked.
I’m not going to do a Medline literature review on the topic but suffice it to say that I’ve been swimming immediately after eating and I’m still alive to type about it :)