Most of us suffer from back pain at one time or another at some point in our lives. But what causes it and what can you do about it? Before we go any further, it is important to state that this column is not a substitute for seeing your doctor. If any of the following are true for you, you must see a physician or chiropractor.

• You are under 20 years or over 55 years
• You suffer sciatica: numbness or weakness in the legs
• Over-the-counter painkillers for back pain fail to control your pain within two or three days
• You need to use over-the-counter painkillers for back pain for more than two weeks
• You suffer from osteoporosis, or a bone scan suggests you have weak bones
• You've suffered from cancer or another serious disease in the past
• You're in constant pain or the pain is getting worse
• You're taking other drugs
• You experience bowel or bladder problems
• You develop back pain during pregnancy
• You develop other symptoms, such as fever or cough

There are many causes for back pain. The most common cause of minor back pain is being out of shape and having poor posture. There are three natural curves of the spine. When a person has poor posture all three of these curves are emphasized. The bones of the spine are held upright and in place by a system of soft tissue which includes muscles, tendons and ligaments. Since the curvature of the spine is increased by poor posture, it stretches these ligaments and tendons, making them less effective at holding the spine together and creating more work for the muscles of the back. Your muscles are the only one of these structures that can contract, and by shortening themselves, hold things in place more effectively.

Being overweight or out of shape can also cause back pain. The abdominal muscles support the back, and when they are weak or overtaxed due to additional weight, it means more work for the muscles of the back. If the back muscles are overstressed they cannot do the additional work required. Back pain is the result.

Here are some exercises you can do to improve your posture and reduce back pain. Consult your physician before starting this or any exercise program.

1. Back against the wall. Stand against a wall and tilt your pelvis until your back is flat against the wall. Do not worry if your feet are away from the wall. Place your hand next to your back, where the curve of the small of your back should be. Keeping your back flat against the wall (so that you cannot fit your hand between your back and the wall) walk your feet toward the wall slowly. Keep going until your back comes away from the wall and you are able to slip your hand between your back and the wall. Do 5 pelvic tilts trying to flatten your back against the wall.

2. Double knees to chest Lying on your back, lift both knees to your chest. Hold for 30 seconds. Repeat 5 times. Gradually increase repetitions.

3. Crunches Lying on your back, fold your arms across your chest and tilt your pelvis to flatten your back against the floor. Tuck your chin into your chest. Tighten your abdominal muscles while raising your head and shoulders from the floor. Hold for 10 seconds and release. Repeat 5 times, or as many times as you are able up to 5. Gradually increase your repetitions.

4. Trunk rotation and stretch Lying on your back, bend your knees. Holding your knees together, slowly lower them to the side until they touch the floor. Hold 30 seconds. Repeat on other side. Do this 5 times on each side. Gradually increase your repetitions.

5. Partial push ups On your hands and knees, arch your back like a cat. Now sit back on your heels slowly lowering your body as you until your buttocks touch the back of your calves, or heels. Slowly reverse the motion so that you are now in the starting position. Repeat 5 times. Gradually increase your repetitions.

6. Lying leg extensions Lying on your stomach, fold your arms, resting your chin on them. Keeping your pelvis flat on the floor, point one foot and lock the corresponding knee. Lift that leg 4-6 inches off the ground. Repeat 5 times with each leg. Gradually increase your repetitions.

7. Alternate leg and arm extensions On your hands and knees, raise left arm and right leg. Do not arch your neck. Keep your back flat; do not arch it. Hold for 10 seconds and release. Do your right arm and left leg. Repeat 5 times on each arm-leg pair. Gradually increase your repetitions.

8. Lumbar Extension Lie on your stomach and place your hands on the floor near the sides of your head. Slowly push your upper body off the floor by straightening your arms, but keep your hips on the floor. Hold for 20 seconds, then relax your arms, moving back to the floor. Repeat 5 times. Gradually increase repetitions.

Leslie Hope has been licensed, certified massage therapist since 1988 when she graduated from the Massage Institute of New England. She is the owner of the Healing Hands of Hope in Boston, MA.