Strengthen your core with this simple yet challenging yoga pose. If you have tight hamstrings, you can keep your knees bent (as shown). But as you become more limber, try straightening your legs to a 45-degree angle as a final position. This will make the pose more advanced.

1 Sit on the floor with your knees bent and feet flat on the floor in front of you. Hold the back of your upper thighs and lift your chest up to straighten your spine. Rock onto your sitting bones and lift your feet off the ground. Firm your abdominal muscles, pulling your navel in toward your spine. Pause for two breaths.

2 Contract your abdominal muscles and raise your hips off the floor. Pause for two seconds. Keeping your hips up, raise your chest, shoulders and head off the floor as high as possible. Pause and hold this peak contraction for three to six seconds. Lower your hips and chest and repeat six to eight times. Be sure to let your head rest in your hands and to keep your elbows pointed to the sides.

This article originally appeared in the Los Angeles Times in the "Good Form" feature of the Health Section. "Good Form" is updated with a new Karen Voight article each Monday.