The purpose of this exercise is to strengthen and build the upper back, chest, shoulder and arm muscles while engaging the core muscles of the lower back, abdominal wall, the glutes and hamstring complex. This exercise challenges the whole body as well as working our stabilizers for balance. This is a moderate to advanced exercise but can be modified for beginners.
Mike RouillardSuperior Personal Fitness
Start with your hands on the ground, feet on the ball, in a plank position:
Bend arms so you move down into a push up
As you push up, bring your knees in so you get a little abdominal crunch
Push legs back out until you are back in a plank position, repeat!
Or, if you want more of a challenge, you can add a Bosu to this move: