Alignement vs Posture – A basic difference

“It has been believed, at least since the time of Galileo Galilei (1564-1642), that mechanical factors strongly influence biological form and function. Indeed, the general concept that mechanics influence biology was articulated clearly over a year ago by J. Wolff (1835-1902), who suggested that the trabecular architecture of bone is dictated primarily by directions of maximum tension that arise in response to external loading. Nevertheless, it has been much more recent that we have learned that mechanics influences biology down to the level of altered gene expression which in many cases appears to contribute to a mechanical homeostasis at multiple length and time scales [1].”

It occurs to me that I owe you a more robust explanation of alignment as I see it used regularly interchanged with the word posture. Let me start by swiping some definitions off

Posture: The way in which your body is positioned when you are sitting or standing.

Explaining posture a bit further, posture is the orientation of parts. You quantify posture by measuring how parts are positioned relative to each other as well as how they’re positioned relative to the ground. Or maybe it’s easier to think of the body on a grid where you can plot the parts on this graph.

Now, to alignment’s definition:

Alignment: The proper positioning or state of adjustment of parts (as of a mechanical or electronic device) in relation to each other.

Both posture and alignment have to do with positioning, but they differ in that alignment’s definition includes the word proper. It is this idea of “proper” that sets the two apart. Now before we assume that proper means “best” or “superior” or assign it a term with implied condescension, let us look at the definition.

Proper is defined as “of the required type; suitable or appropriate.”

If you drive a car you’ve probably had to have your wheel alignment (not wheel posture) adjusted at some point. In this case your mechanic is not finding the most attractive position for a wheel. In fact, wheel alignment is not about static positioning at all but how, once moving, the interaction of a system–the road, the wheels, the tire, suspension components, and other stuff that I know nothing about–doesn’t inflict excessive damage on any single part making up the system.

To find optimal wheel alignment the mechanic must consider the material fatigue points, the forces created by the speed, terrain (does your vehicle go off-road?), tire pressure, etc. In short, alignment includes the consideration of FORCES. Or said another way, posture is the visible orientation of parts and alignment encompasses the invisible forces created by particular movements.

Many of you are working on your alignment, which is not to say that you are not working on your posture. You are, by definition, working on postural adjustments. But you are working on these postural adjustments for better alignment–to change the way you create forces that become loads experienced by your tissues.

The term “proper” begs the question “are there requirements when it comes to the machine in question (read: the human body).” And the answer is, of course there are. Just as there is a physiological homeostasis for the body, there is a mechanical homeostasis as well.

Research into the nuances of each load-induced disease will start to come now that mechanical loads and cellular responses (mechanotransduction) is understood a bit more. As for musculoskeletal issues, much of our current rationale for various exercises and postural adjustments stems from load research. (Although it’s interesting to note that mechanotherapy researcher K.M. Khan found that mechanotransduction is not currently presented in physical therapy curicula. ” Our informal ‘‘results’’ (unpublished data) suggested that mechanotransduction was not being taught as an important biological principle in physical therapy programmes [2].”)

I don’t think there will come a time when we’ve exhausted the discovery of what a body needs (we’re nowhere close to assessing movement in a nuanced way and after 50 years are still working with 30 joint axis out of of 300) but until then, know that it is not a “perfect position” you are after, but a set of forces that allows your system to function best as a whole.

1. Vascular Adaptation and Mechanical Homeostasis at Tissue, Cellular, and Sub-cellular Levels. Cell Biochemistry and Biophysics February 2008, Volume 50, Issue 2, pp 53-78

2. KH Khan, A Scott Br J Sports Med 2009;43:247-252doi:10.1136/bjsm.2008.054239 Mechanotherapy: how physical therapists’ prescription of exercise promotes tissue repair.