All I know is if I don't get calcium and magnesium on a hot sweaty ride I WILL get cramps. If I take extra (usually Endurolytes), then I don't.

A friend of mine brings a handful of Endurolytes caps on hot weather and almost always winds up giving away what she doesn't take, to other people who are cramping.


Last year I looked up some studies on mineral losses in sweat, and they were significant. It's too early for me to go chasing those links down again, but I probably posted a link at the time.