Reader Question #3

Question: "I read somewhere that tall people are more like to have bad knees and backs because they're over-nourished. That is, our bodies are over-engineered for height, and the fact that we eat well enough to grow so tall means that our size over-reaches our joints. Any thoughts?"
Answer: While there is a connection between the release of growth hormone and nourishment, I do not believe that over-nourishment will cause a person to out-grow their joints (not due to height anyway). It is true, however, that over nourishment can cause a person to grow to heavy for their joints, which can be a serious problem.

While there are some conditions which cause people to be very tall and have joint problems (i.e. Marfan's Syndrome, a genetic defect in collagen production)the back and knee problems experienced by taller people are most likely a result of musculoskeletal (somatic) dysfunction. Simply stated, taller people are required to bend down more than shorter people. This will initially cause problems in the spine. Normal physiologic motion of the spine includes three types of movement: Neutral movement(in which the spine is either flexed or extended with no side-bending), Type I movement(in which the spine is sidebent one direction and rotated the opposite), and type II movement(in which the spine is sidebent one direction and rotated in the same direction). Type II movement occurs at the extremes of physiologic range of motion, i.e. the farther you bend over the more likely you are to induce type II motion. Type II motions can lead to type II somatic dysfunctions, in which the spine gets "stuck" in a position which is flexed/extended, sidebent, and rotated relative to neutral. Type II somatic dysfunctions tend to be more damaging/painful than type I or neutral dysfunctions(Caused by Type I motion and Neutral motion respectively). Once a dysfunction is induced, this causes the person to adopt a shifted neutral standing position (often this shift is imperceptible to the person). The rest of the body will then undergo a compensatory shift, thus putting abnormal strains on other joints, specifically the knees, sacroiliac joints, and inominates(pelvis).

While I can't guarantee this is perfect (and I know its not the only possible explanation), this is what I believe to be the most likely cause of taller people being more likely to have joint problems than shorter people.

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