I haven't had problems with cramps in about three years since I've been umpire "inside" all three winters...never had more than about 3 weeks off from umpiring. I drink plenty of water daily, drink gatorade about 1 1/2 hours before game, and have a snack before the game. If doing two or more, I'll get a snack between...something small (like a full pizza
) Seriously, know what your body needs and you'll be fine.
Always stretch those calves before and after the game. If I do a lot of games in one day, I'll come home and my wife makes me do some yoga stretching. Feels pretty good.