While "good posture" is considered a sign of good movement health, there are true and false teachings about how to achieve it.
The popular view of good posture is that it is something you have to maintain; it's a "good" holding pattern. The concepts, "neutral spine position" and "alignment", fall into this category. "Shoulders back, chest up, stomach in" are typical instructions for maintaining good posture.
The popular view and the typical instructions I have described constitutes a false teaching about good posture -- and by false, I mean detrimental.
Here's why: It adds strain to an already strained muscular system and unnaturally restrains movement.
The common teaching about good posture assumes that good posture is not the natural or free condition and that one must therefore do something to maintain it. This view may seem reasonable and inevitable; "If you don't do something to maintain good posture, you're left with the poor posture you had, already."
But an unrecognized truth underlies this assumption: Most people are beset by habitual muscular tension patterns that drag them down from good posture, tension patterns of which they are unaware because they are so used to them, tension patterns formed at the time of injuries or of emotional stress (i.e., nervous tension).
In actuality, good posture is the easiest condition to maintain -- if you are free of habitual tension patterns. If not, then you must do something to counteract those tension patterns, to restore good posture. That's the condition most people are in.
This assertion may be hard to accept until you have experienced the reality of what happens when you get free of your habitual tension state.
Massage and bodywork typically seek to alleviate habitual tension, but with rare exception, they do not alter a person's postural set because to do so would require a second step: to develop better coordination.
Coordination is the basis of good movement, good posture, good alignment.
Posture, viewed another way, results from moving into a certain shape and holding it. It's a function of movement.
Most movements are developed by learning. So is posture.
The difference is that injuries and stress change movement patterns in lasting ways that are commonly beyond the ability of people to change; these movement patterns persist on automatic. That's why teachings about posture recommend counter-actions to those movement patterns.
So, what's the answer? Are we forever destined to poor and worsening posture as we grow older?
The answer is, no. But what is needed is a way to undo habitual muscular tensions formed by injuries and stress, not to counteract them (either through "good posture" disciplines or through strengthening of muscles).
Such a way exists. The discipline of clinical somatic education teaches and employs exactly such a way.
All animals with a backbone do a certain action instinctually upon arising from rest, as they become active. This action, commonly mistaken for stretching, involves a strong muscular contraction followed by a leisurely relaxation; different animals have different patterns, but all do it in some form. This action pattern called, "pandiculation", refreshes the brain's body image and purges accumulated tension. Birds do it by shrugging their wings back, reaching their legs back, one at a time, and then flapping their wings; cats and dogs do it by first bowing, arching their back, and then shaking. Humans do it in the natural "yawn and morning stretch" (different in performance from the calf or hamstring stretches athletes do).
Clinical somatic education uses techniques that activate this genetically-present action behavior methodically and in a magnified way to free people from the grip of tension patterns formed by injury and stress. In the case of clinical somatic education, we apply the contraction/relaxation behavior to places where the person holds tension; with injuries and stress, these tensions always exist in patterns, so it's not a matter of "releasing muscles", but of releasing entire patterns of tension. The result is a lasting release of muscular tension. Then, we teach movement patterns that link muscle groups together in certain inherently well-organized patterns of coordination, to replace less well-organized pathological patterns. It's a lower-effort, easier, more efficient condition of living.
No longer is the person dragged down from good posture by habitual muscular tension. (S)he is free to stand and move at her or his full stature and in the easy balance that free and well-coordinated movement permits.
The results of pandiculation distinguish the good posture of freedom from tension from the 'good posture' maintained by pitting one muscle group (used to maintain good posture) from other muscle groups (held tight by the lingering effects of injury and stress).
Easy balance is the natural state, whether at rest or in movement. Good posture isn't something you maintain; it's nearly effortless, the product of good balance and good coordination.
Read a research article on pandiculation.
To see and hear how we apply pandiculation to back trouble, view Back Exercises for Lower Back Pain. See other examples of pandiculation instruction in the somatic exercises shown on YouTube channel "Lawrence9Gold".
Read articles on movement health conditions, such as sciatica, stress conditions, such as headaches, and on postural distortions, such as unequal leg length, at Somatics on the Web