I use the coaches' stool, the one mounted on a spring. It lets you sway a little to get to some balls and you can bail out pretty quickly (as I frequently do). But my thumb and forefinger (even outside the mitt) are pretty much numb for a couple of days after a bullpen. So far goose eggs on shins are as bad as I've suffered, but he's just 13 so I've still got time for an emergency room visit.