By RealJock Staff

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.

Benefits
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.

Muscles Worked
Abdominals, Shoulders

Starting Position
Start in a plank style pushup position so that your shins and shoelaces are on the stability ball and your hands are on the floor. Your head and neck should be in line with your spine. Keep your toes pointed to avoid perching on the ball with your toes (see Photo 1).

Exercise

1. Keeping your hips and core stable throughout the movement, tuck your knees up towards your chest and shoulders so that the ball rolls towards your head, performing a posterior pelvic tilt so that your hips tuck up and under (see Photo 2).
2. When you have brought the ball in as close as you can, 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 back drops and arches (see Photo 3)
3. From your full extension, slowly bring your feet back toward you and repeat the entire movement from the starting position.

About Billy Polson: Billy Polson is the founder and co-owner of DIAKADI Body , which was voted the best personal training gym in San Francisco by CitySearch in 2006. A competitive swimmer and triathlete in his own right, Polson has over 15 years of experience working as a coach and trainer, and was recently named by Men's Journal (December 2005) as one of the Top 100 Trainers in America.