Cramping is still pretty much a mystery; mostly because no one has really studied the issue.

I could not disagree more with that statement. There have been hundreds of studies on cramping. The fact is that few actually die from cramping so it just is not a high profile medical issue to solve. If based on the number of research studies, cancer should have been cured long ago.

I have suffered cramping since about 12 years old. I too have experienced the 40 mile cramps the OP went through. When someone figures out how to prevent cramping you will be, in the words of Forrest Gump, a Gizzillionair. I will be the first to pay good money for the cure. I figure cramping is your brain telling your muscles that enough is enough.