This exercise strengthens your back and abdomen muscles.

1. Positioned on hands and knees, place your hands directly under your shoulders and straighten your arms.
2. Tighten your belly muscles by pulling in your belly button toward your spine. Be sure you continue to breathe normally, and do not hold your breath.
3. Lift your left knee and bring it toward your elbow.
4. Slowly extend your leg behind you without completely straightening it. Be careful not to let your hip drop down. Avoid arching your back.
5. Hold your leg behind you for about 6 seconds.
6. Return to your starting position.
7. Do the same exercise with your other leg.

Repeat 8 to 12 times for each leg.