Train your core muscles with this simple yet highly effective exercise. It's easy to include in your daily abdominal routine, and you will notice how tight and flat your abs feel after just a few times.
1. Sit upright on a padded, level mat with your feet flat on the floor and your knees bent. Place a small inflatable ball (or firm pillow) behind your lower back for support. Lean back against the support, and move your arms away from your body on the floor. Without using your arms, maintain your balance on the ball while pressing your navel down toward your spine to keep your abdominals flat.
2. Concentrate on maintaining even pressure on the ball to hold your balance, and keep your hips and shoulders facing squarely to the front. Exhale and bring both arms straight out in front of you, above chest level. Simultaneously contract the muscle in the front of your right thigh (quadriceps) and straighten your right knee, raising it off the floor. Pause with your fists reaching toward your right foot and remember to keep your abdominals flat. Inhale and lower your right foot and both arms to the floor. Repeat, but this time on the exhale raise your left foot and both arms up. Continue to alternate legs until you have done 16 to 24 reps.
Voight is the creator of a line of fitness DVDs, including "Full Body Stretch" and "Ballet BodySculpt."