Start with the ball resting on the floor. Your stomach and lats should be braced and ready to fire but still in a static position. Get everything tight and fire the ball into the wall as hard and fast as you can. Try to make the ball explode. The object is to go from a static position( no movement) to dynamic (explosive movement) as fast as possible. This is sports. All too often we train the stretch reflex but not the static to dynamic contractions that are often seen in sports. Yes, the stretch reflex is important but it is not the dominant type of contraction in all sporting events!