This exercise provided courtesy of Billy Polson, founder and co-owner of DIAKADI Body, which was voted best personal training gym in San Francisco by CitySearch in 2006.
Knee tucks are more than an abs cruncher. The use of the stability ball trains your abs to have a greater degree of stability and control, while also improving your shoulder stability and endurance.
Start in a plank-style pushup position so that your shoelaces are on the stability ball and your hands are on the floor. Keep your toes pointed to avoid perching on the ball with your toes. Start with your spine in a perfect 'S' curve, with a slight curve in your lower back, your shoulder blades back and chest front with your neck and head in line with your spine. The goal is to keep this spinal alignment and to keep you lower abs contracted throughout the movement (see Photo 1).
- Tuck your knees down towards the floor as you roll the ball towards your head.
- When you have brought the ball in as close as you can without allowing your spine to change, reverse the motion and extend your legs back out to the starting plank position. Control the movement throughout. It is crucial that you not push so far that your hips drop. From your full extension, slowly bend your knees again and repeat the entire movement from the starting position.