4 Cool Core Exercises

Supine trunk curl on stability ball

Total reps: 5-15. Lie back down on a stability ball or Resist-A-Ball. Keep your arms X-crossed at your chest. Curl your abdominals toward the hips, keeping your head and neck aligned with spinal column. Do not jut head forward. Keep feet planted on floor; do not move them. Most importantly, make sure the ball does not roll as you crunch!

Easier variation: Keep your arms extended out in front. Harder variation: Curl up as high as possible and hold the crunch for three seconds. Never let the ball or your feet move.

Stability ball leg lifts

Total reps: 5-15. Sit on the floor, legs straight out (but don't lock out knees) and cradle the ball between ankles. Make sure half of the ball is above your feet and half of it is below, so that it doesn't pop out. Keep hands off floor at all times. With legs straight, raise the ball 6-12 or more inches off the floor, keeping your back upright. Hold for one second, then lower to floor. Always keep your legs straight. Harder variation: Don't let the ball touch the floor between reps. Bonus: Adductors (inner thigh muscles) get targeted.

V crunches the right way

Total reps: 5-15. Sit on a bench, with your thighs parallel to its length, and most of the bench behind you. Keep hands off the bench at all times. Extend your legs straight over the bench and keep them together. Lift feet 6-30 inches from the bench, then bend knees toward torso. Legs must stay together; do not flare out your thighs. Bring the knees tightly into chest and hold this position for two seconds. Then extend your legs to straight again and hold the extension for one second. Do not let legs touch bench.

BOSU board back extensions

Total reps: 20. Lie tummy down on a BOSU board so that the board acts as a balancing point. BOSU stands for both sides up. BOSU boards look like half a sphere, or half a stability ball. They have a soft rounded side, and the other side is flat. So when you lie tummy down, make sure that you are lying on the soft, rounded side, not the flat, hard side.