I just rode in a 30 mile race this weekend and about 25 miles into it I got a Charlie-horse in my right calf. It took about 30 seconds to shake it out before I could go again. This happened a few months ago when I rode hard on a 17 mile mountain bike trail except in was in both calves and also my upper legs. Whats the best type of prevention for Charlie-horses? I am 44 and don't get to ride but maybe a couple times a week for about 10-12 miles at a time. I walk a couple miles each night and take a daily multivitamin. Do I need to increase my potassium intake, exercise more or is this just something I need to accept at my age? Thanks for your help.