it could be dehydration, potassium or a number of other things. My calves are always twitching and spazzing out. My docs can't figure it out so I take muscle relaxers at bed time when they are really bad or I will wake up screaming in pain.
First 5K 9/27/20 46:32 - 11 weeks post op (PR 28:55 8/15/11)
First 10K 7/04/2011 1:03 First 15K 9/18/2011 1:37
First Half Marathon 10/02/2011 2:27:44 (PR 2:24:35)
First Half Ironman 9/30/12 7:32:04