Swiss-Ball Jackknife with Pushup

START: Assume a pushup position with your arms completely straight. Position your hands slightly wider than and in line with your shoulders. Rest your shins on a Swiss ball. Your body should form a straight line from your head to your ankles.

MOVEMENT: Without changing your lower-back posture, roll the Swiss ball toward your chest by pulling it forward with your feet. Pause, then return the ball to the starting position by rolling the ball backward. Keeping your shins on the Swiss ball and your body straight, lower your body until your chest nearly touches the floor into a pushup. Pause at the bottom, and then push yourself back to the starting position as quickly as possible. That is one repetition.