Many gym rats know this movement from the awkward facedown weight machine. It’s not only uncomfortable because of the stiff and ungainly positioned calf supports, but also, with too much weight, it can cause lower back and hamstring injuries. By subbing in the Swiss ball, the stability quotient is increased because of the uneven workout surface, resulting in better balance. It helps build powerful strides, since the hamstring is the key muscle that lifts the heel. And because it works in tandem with the ACL, which stabilizes the knee, it helps keep this leg joint in shape—the bane of runners everywhere.
Lie face up on the floor with arms flat at the side (palms down). Place calves on top of the Swiss ball, bringing hips up and straight in line with lower back and shoulders and upper back flat on the floor. This is the starting position.
Keeping abs tight, roll the ball along the heels of the feet toward the butt, lifting the knees and hips up at the same time. Roll the ball until feet are flat on it. Pause then push ball back until legs are straight and back into the starting position.
Do 10-12 reps. For a harder workout, straighten one leg up and off the ball and do the same motion on the opposite leg. Then switch legs and repeat.
Demonstrated by Mike Lynch, a personal trainer with 20 years experience and the owner of lynchfit.com.