Posture = sum total of bodily experience over time
I like to redefine or contemplate posture as the sum total of movements you make over a given period of time, whether that be an hour, a day, a year, a career, or a lifetime. Our posture is certainly different in yoga or running than in a couch, and so this wider perspective can help us to see which movements we are making and not making, and how much time we are spanning in these different patterns of movement. We even have some movement systems such as Continuum that are exploring unpatterned movement, moving as a liquid, in a creative exploratory state.
To recognize that there are some movements you likely haven’t made in a long time is useful in many ways. Generally, if we stop making certain movements, such as a deep back bend, or strong core activation, then our body will eventually lose or weaken (or never attain) the capacity to make those movements. Our body is so responsive to our movement habits, if we tell it we don’t need to back bend, or side bend, or twist our spines deeply, or do a pull-up or plank or whatever, then over time it literally structures itself in terms of nervous system patterning and connective tissue/muscular set length and/or strength to inhibit that possibility. In terms of fitness, strength and mobility, we tend to lose what we don’t use.
We have a spectrum of “postures” we make while using a computer or phone, and when people spend a lot of time within this narrow spectrum, their body will generally start to adapt itself around this narrow range of inputs. The now classic head forward posture which has become so prevalent in postmodern times, is a chronic postural form that many bodies adopt. Considering how much more weight the “postural” muscles must support for each mm or inch the head moves forward out of the gravity line where the weight is supported by the structural relationship to gravity, into zones where the weight is more and more supported by muscular, nervous system, and fascial effort. (Physiotherapy research shows for every inch you move your head forward the relative weight of your head will increase by average of 10lbs)
In yoga, asanas are literally translated as shapes or postures, even a pushup is a posture in this regard. The human body is great at specialization, but not always to its own benefit. To keep a generalist perspective in terms of variety of movement, and even as a way of contemplating antidotal movement to our habitual tendencies is relevant here.
For instance in my clinical practice I see folks with desk jobs, sitting 40 hours a week at work, then sitting for another 20 hours to eat and relax, and then getting on a bike for their workout, generally build up so much tension in the hip flexors (and elsewhere) that symptoms of back pain are relatively common. Spanning time in a split squat, prolonged quadriceps stretches, and sphinx or upward dog can generally be nourishing input that, over time can lend more balance to the structure and function of the body, reducing the symptoms of over use. Intelligently analyzing each individuals structure from this perspective can bring about big changes in internal perception and symptom dissipation.
We could layer in a more psycho-spiritual perspective as well, considering the various emotional, sensorial and somatic states that arise in the consciousness of the individual, and how these perpetuate or expand beyond the palate of habitual tendencies, but I will save that for another discussion.