Incorrect posture is a major cause of back pain. The muscles that maintain the body's posture and support the body against gravity are called postural muscles or tonic muscles. Other muscles that move the body are called phasic or movement muscles. Examples of phasic muscles are the gluteals and abdominals. Postural muscles include the erector spinae muscles that run down the spine, the hamstrings running down the back of the legs and the chest muscles or pectorals. Postural muscles, which have great endurance, can support the body for lengthy periods. However, if they become tight, posture will become distorted over time and back pain will result. Muscles also work together and compensate for each other. So if the postural muscles are weak or tight, the phasic muscles will have to carry additional load and will tire easily.

Because the spine has a natural S shape, if we look at the profile of someone with good posture, we will see the S shape in the back. Inflexible or tight chest muscles will tend to pull on the shoulders, which will round the shoulders and upper back and cause upper back pain. If the hamstring muscles are tight, they will tend to pull on the pelvis (because the hamstrings are attached to the pelvis), causing a rounding of the lower back. This will cause lower back pain as time goes by. Just because you are flexible in one muscle doesn't necessarily mean that your other muscles are flexible. All of the main postural muscles need to be stretched regularly to prevent tightening. If your postural muscles are naturally flexible, they will allow the spine to retain its natural S shape. This will greatly lessen your chances of experiencing back pain.

Our lifestyles involve prolonged sitting and minimal exercise. This inactive lifestyle is not how the body evolved to work; a few thousand years ago we spent most of our time walking, hunting, gathering water and so on. We need to make the effort to counteract the effects of the traffic-desk-TV couch lifestyle.

The back postural muscles include the erector spinae muscles and the upper trapezius. Here is a simple yoga stretch, the Upward Facing Dog. Lie on your stomach, with your legs together. Place your hands underneath your shoulders, flat on the floor. Straighten your arms, pushing up. Look up. Keep your weight on your toes. Don't bend too far backwards-just stretch gently as far as you can.

Another set of important postural muscles run down the back of our legs-the hamstrings. This is a basic hamstring stretch: Sit on the floor and extend the right leg straight in front of you. Bring the left foot to your right knee. Relax the left leg. Reach forward with your right hand and hold on to your right ankle. If possible, hold your toes. Hold this stretch for 5-10 seconds. Repeat with the left leg.

The front postural muscles include the pectoral muscles. A simple chest stretch: Stand in front of a door frame. Reach back and hold the door with your right hand. Straighten your right arm and push your chest slightly forwards, being careful not to strain your shoulders. You should feel a stretch in your right chest. Hold for a few seconds. Repeat on the left side.