The supine leg raise is often used to target the lower abs. However, when the legs are elevated from a supine position, the hip flexors become the prime movers, not the abs. Leg raises can put stress on the lumbar spine. Thus, alternative exercises are recommended. It is also important to note that the midsection is not divided into lower and upper halves. The rectus abdominis is one muscle.

Start by lying in the supine position (on your back) on a workout mat. The legs should be straight and the palms should be face down under the buttocks. This will assist the pelvis with leverage as you initiate the leg raise. Next, with the feet together, lift the legs approximately 15 to 20 inches off the ground. Slowly lower the legs to the starting position and repeat the exercise. You should breathe out as the legs go up.