Whitewater

assuming you are right-handed thats the playing arm holding the ciapin (beater) not the one supporting the bodhran?

much depends on the style you adopt for beating. do you turn your wrist and beat with your knuckles nearest the skin? do you hold the ciapin in a pen grip or between thumb and middle fingers? Are you gripping the ciapan very tightly. Do you beat in the same place on the skin or move around (play from both elbow and shoulder). often when playing fast tunes players lock up shoulder wrist and fingers (often so as not to let the ciapin fly out of their hand) this will cause you to cramp very quickly.