This exercise provided courtesy of Mike Clausen, founder and co-owner of DIAKADI Body training gym, voted best personal training gym in San Francisco by CitySearch in 2006.
Many people overwork their upper abs while neglecting their lower abs, which are weaker and harder to target. Knee crunches work both together, developing your upper and lower abs in balance.
Abdominals (upper and lower)
Lie on your back on the floor with your knees bent so that your feet are resting lightly on the floor and your knees are folded toward the ceiling. Keep your pelvis in a neutral position. Bend your elbows straight out to the side as you place your fingertips just behind your ears. Be careful not to pull on your head; your hands are there to help you balance and stabilize your head, not to do any of the work (see Photo 1).
- From the starting position, engage your abdominal muscles, squeezing downward just below your belly button. As you do this, be careful not to tilt your pelvis upward or dig your feet into the floor. The abdominal squeeze will bring your shoulders just slightly off the floor and generate a slight curve through your center. At the same time, begin to bring your left foot off the floor, with the idea of taking your knee toward your chest. This motion should be generated from that same central abdominal contraction (see Photo 2).
- Keeping your right foot lightly on the floor, use that abdominal contraction to roll your upper body up off the floor as you bring the left knee toward your chest, until your shoulders come fully off the floor and your knee is as far in as it can come. Keep your neck neutral, so that your chin stays off your chest (you should have room to fit your balled fist between your chin and your chest), and try not to bring your elbows forward beyond a 45-degree angle (see Photos 3 and 4).
- Lower the left leg back to starting position as you return your shoulders to the floor (see Photo 5). Immediately repeat the knee tuck and crunch, again on the left side. After you have done a set of knee tucks with the left leg, repeat the exercise with the right leg.