does anyone else get cramps while they're surfing? I usually get them on my hamstrings after a while (2-3) hours nonstop water time. Also, when the waters a little chilly and i'm not wearing a wetsuit or the waters cold and i'm only wearing a spring suit, my arms get sore really fast. I'm very active (I swim 2-4 miles a day nov.-march) so I don't know whats causing these.