Living and balancing on just two legs is a miraculous skill we never think about. In truth, it's amazing we don't fall over every time we sneeze or lift a gallon of milk from the refrigerator. Our healthy existence depends upon our marvelous ability to keep our relatively tall and slender column safely upright even while we thoughtlessly move, work, play and change positions. That we can instantaneously adapt to almost any position or any activity without toppling over is a scientific mystery, and yet most of us take our vertical brilliance for granted.
As with any physical structure that dares defy gravity, such as a tower, imbalance is dangerous and threatens to bring it (and us) crashing down. It also loads one side of its structure and foundation more than the rest, which challenges structural integrity, fostering fatigue, and resulting in premature failure. The famous Leaning Tower of Pisa had to be closed when its imbalance reached six degrees of lean. The tower's foundation showed evidence of damage and engineers feared it would soon fall. It was eventually re-opened but not until its foundation had been significantly increased to handle the existing lean and to prevent further decline.
Your body is no different than the Leaning Tower of Pisa. Living with a chronic lean damages your skeletal structure. It overloads and deforms joints and works muscles to exhaustion. Since your body has a much greater height to base ratio than Pisa's Tower, a six degree lean for you has a much greater impact upon your spine, hips, knees, and feet than the tower inflicts upon its base of support.
We measured the lean of 700 high school students and found the average value was six degrees at one school, where they rarely carried a backpack, and TWELVE degrees at another school where students carried all of their books in their backpacks. Since research has found that the spine's base experiences three times as much loading for every degree of lean, it's no wonder 65% of the backpack-carrying students reported back discomfort every day.
The first of four non-negotiable goals for repairing and maintaining a healthy spine is to sit, stand, walk, work and play correctly upright, with head over shoulders over hips and feet. Your mom was right after all!