Do this exercise slowly. Try to keep your body straight at all times.

1. Start on the floor, on your hands and knees.
2. Tighten your belly muscles by pulling your belly button in toward your spine. Be sure you continue to breathe normally and do not hold your breath.
3. Raise one arm off the floor, and hold it straight out in front of you. Be careful not to let your shoulder drop down, because that will twist your trunk.
4. Hold for about 6 seconds, then lower your arm and switch to your other arm.
5. Repeat 8 to 12 times with each arm.
6. When you can do this exercise with ease and no pain, try it with one leg raised off the floor. Hold your leg straight out behind you. Be careful not to let your hip drop down, because that will twist your trunk.
7. When holding your leg straight out becomes easier, try raising your opposite arm at the same time. Repeat steps 1 through 5.