Certain movements such as D-ball Slams and Wall Ball may appear to be contra-indicated in situations such as hip or knee replacement. Not so! Once a safe movement base of squats (above 90* for both these populations) is established (Read Greg Everett’s article on the squat for squat info) one may progress to both these movements by shortening the range of movement, keeping the load nominal, and insisting on PERFECT form. One may shorten the ROM of the D-ball by slamming to one or two stacked bumper plates. Wall Ball can be attacked with partial squats (push-ball) and gradually progressed to 90* knee flexion. Check out the article Scale This! for more.