Might be problematic if you have a heart condition - or it might get it restarted if it stops.
A guy I shoot competition with has a pacemaker and shoots a Glock 9mm. One day, we were at a match and he's burning through a stage pretty well. Suddenly he jerks to a stop, almost falls over, almost drops his gun and grabs his heart. He had this look, like WTF was that on his face and stopped shooting. He said his pacemaker shocked the **** out of him.
A few weeks later, he was back shooting again and hasn't had a problem since. He said his doc found some kind of problem with his pacemaker and corrected it, but basically, the pacemaker was picking up the thumps from his pistol, thought it was a bad rhythm and shocked the **** out of him to correct the arrhythmia. Oops.