A charlie horse is the sudden painful knotting and cramping of a muscle, particularly the calves. I have had them so bad at times if feels like there is a baseball, looks like it as well, under the skin where my calf muscle is supposed to be.
mtgman, I feel like I am having a tough time processing the amount of water needed to stay well hydrated. How about you? I have been mixing it up with a bit of gatorade on the days I really need to get work done outside.