I played football twice the other day, first just a little kick about in the park and the second in a 5 a side match someone begged me to play (lack of numbers otherwise). By the middle of the match, I had cramp in both my calves which was surprisingly painful when trying to run. Wish I had known I was expected to play later on, I would've conserved my energy in the first kick about.
Like heroic, I've never had cramp before whilst actually doing sport so it was weird.