Abdominal exercises may be difficult if you have back problems. Low-impact abdominal exercises that support the back are beneficial for many people, not just those with lower back problems. Seniors and women who recently gave birth may also be told to try gentle exercises lying on their back in a supportive, low-impact position, though everyone may benefit from these exercises. Work the abs two to three days a week unless told to do more by your physician. Only do as many reps as you can do with good form.
The pelvic tilt exercise is performed lying face up on the floor to stabilize the back. The exercise is subtle, but effective for teaching someone how to contract their abs and find their neutral spine position. This ability to pull in the abs is necessary to perform many other abdominal exercises correctly and safely. Start by lying on your back with your knees bent and the feet on the floor. Cross your arms on your chest chest or relax them on the ground. Your lower back should be arched slightly. Once the abs are engaged, press the lower back into the floor. The longer you can hold your back pressed down, the better.
Heel slides build off of the pelvic tilt exercise by adding leg movement to challenge the abs ability to keep the back flat. The starting position for the exercise is the same as the pelvic tilt. From a lying position with the back flat, slide one heel along the floor until your leg is straight and the toes are pointing toward the ceiling. Keep the pelvis tilted to work the abs. If the back comes off the floor, the abs are not working--so only straighten your leg as much as you can be without your back arching up. Bend your leg back to the starting position, then slide your other leg along the floor.
The marching abdominal exercise is different than marching in place or marching standing up, though the movements of the legs are similar to those of the bicycle maneuver that involves "pedaling" your legs while lying down. Lie on your back with your knees bent, with feet on the floor about hip-width apart. Push your lower back pushed into the floor by pulling in the abs. Lift one leg and move it toward the chest. Keep your knee bent at a 90-degree angle and keep the back pressed into the floor. Return to the starting position and repeat for the other leg.