While facing the floor, support your extended body off of the ground with only your elbows and toes. Your elbows should be on the floor directly below your shoulders and your feet should be close together.
Keep your body as straight as you can from head to toe. This exercise will use your abdominal muscles to keep your body from sagging toward the floor. Keep your abs tight and solid.
TIP: To intensify the plank exercise, move your elbows further ahead so that there is more distance between your elbows and toes.