Main Muscle Worked: Abdominals
Other Muscles Worked: None
Equipment: Exercise Ball
Mechanics Type: Compound 

Tips: Works more of the lower abs. Start in a push-up position and place your lower shins on top of the exercise ball. While keeping your back completely straight, pull your knees in towards your chest, allowing the ball to roll forward under your ankles. Squeeze your abs and then straighten your legs, rolling the ball back to the starting position.