This is a series on low back pain. If you missed the summary of causes, go back to Part 1.

“Sit up straight!” your mother would correct you. It wasn’t only because you looked bad slumped over, she knew that it was bad for your back, probably because she suffered from back pain herself.
The two most common postural causes of low back pain are slumping and carrying too much weight in front. Both the rounded back and the sway back positions cause the muscle strain and weakness that leads to low back pain.

The primary postural stress is a slumped posture. Unfortunately, this is our popular casual American look. It is the equalizer, keeping you looking cool and relaxed, not standing out in the crowd. Sitting back on the base of your spine between your butt bones (sacrum and coccyx) rounds the lumbar vertebrae in the lowest part of your back outward toward the chair. These five chunky vertebrae are slightly wedge-shaped and are meant to stack up in a curve. In architecture, the arch is the strongest form of support. In the low back, this foundation structure supports the weight of the torso. When the curve is reversed as in this posture, it disrupts the strength of the arch and forces the back to work harder to maintain the curve. Eventually the muscles get weak and vulnerable from the mild overuse, causing low back pain. The other detriment to the rounded back is that the chest and abdominal muscles shorten and tighten, rounding the shoulders and causing a head-forward posture that leads to upper back and neck pain.

The easy correction is to change the position of your lumbar spine to reestablish the natural curve, that strong architectural arch. To do that, rock your pelvis forward until you are positioned just in front of the highest part of the bones you sit on. When you do that, just like stacking kids blocks, the opposing curves of the mid-back and neck will naturally correct and you’ll be sitting straighter with your head back and balanced on top of your spine. It takes no effort to make this change, but your muscles will tire since they have become weak, returning you to the slumped position. Strengthening the core muscles will help you maintain this comfortable posture and significantly reduce back pain.
The second postural stress is caused by the imbalance of a heavy belly. The added weight in front either from pregnancy or from the “beer belly” shape puts a strain on the muscles of the low back as they try to hold the spine steady and upright. Pain is caused either by overuse of the muscles or compression of the spine from the “sway back.” When muscles become strained to their limit, the ligaments stiffen reflexively and protectively, compressing the joints at the base of the spine (lumbosacral and sacroiliac). The compression stimulates the nerves in the joints, and there you have your low back pain.

Positional stress is caused by any position that must be held for a while, like sitting at a computer or standing over a counter or a workbench. If there is a weight involved like holding the arms forward on the keyboard, controlling a tool or carrying a child the stress load is increased. The muscles work harder, the blood flow slows down with the tension, nutrients and oxygen don’t get delivered, waste products build up and you’ve got pain!

Posture and positional stress factors are evaluated in patients presenting with any back pain at my Neuromuscular Therapy center near Boston.