It is my distinct impression (after many decades of practicing Physical Medicine) that most people do not appreciate the profound influence and consequences that different postures have on their musculo-skeletal system and on their general health and well-being.
I shall attempt to define elements of posture that are pertinent to human structure and function, which generally involves better understanding our "upright stance", and how departures from upright stance can affect development and function of the vertical spine. The critical role of activity--or lack of it--will be reviewed (see also: Blog 2-Exercise).
One basic fact that needs to be acknowledged is that we humans differ fundamentally from the other animals in this world in that our spines--during most of our daily and meaningful activities-- are oriented vertically and not horizontally. This particular orientation of our spines with respect to a major, ever-present force (gravity) induces a bio-mechanical compensation involving paraspinal muscle function that osteopathic medicine chooses to define as the well-compensated spine.
The well-compensated spine is best exemplified in the lower back/lumbar + sacro-iliac areas, where the pelvis (a group of seven bones in a relatively rigid configuration), supported upright and horizontally by lower extremities, transitions into a relatively mobile and vertical lumbar spine. Any unlevelness of the pelvis and sacrum generally exposes the lumbar spine to side-bending stress, for which most healthy lumbar spines easily compensate thru segmental side-bending and rotation, to maintain the (relatively large and less mobile) torso/upper body balanced above the pelvis. An exam of an individual's lumbo-sacral (LS) spine at rest, lying prone, will generally reveal patterns of LS segment rotation that will infer whether that person's spine is well-compensated/functional, or dysfunctional.
The high prevalence of pelvic unlevelness constitutes an underappreciated contributor to postural side-bending stress, especially in the LS spine. Given the general adequacy of the lower spine to compensate (manifesting as mild scoliosis), there are questions as to the relevancy of treating this. However, greater degrees of sacral unlevelness (on the order of 9-10 mm =3/8") result in greater degrees of compensatory spinal work (to maintain erect posture against gravity), which also involves rotational stress. Such postural stress of compensatory side-bending of the LS spine results in cumulative micro-trauma, which can result in "disc" disorders (disc incompetency) that commonly have no distinct identifiable initiating event. Orthotic regimens can address pelvic unlevelness and reduce compensatory sidebending, reducing an obstacle to recovery in certain disc syndromes.
Where there is a palpable departure from well-compensated functional geometry, there is a high likelihood of dysfunction and at least mild pain. Depending on the pattern of this dysfunctional geometry, a doctor or therapist may perform specific manual treatments, or recommend specific stretches, to reduce pain and improve function by facilitating return of normal mechanics.
Proper development and functioning of the lumbo-pelvic region is critically linked to dynamic movement, which basically is upright posture while moving on two legs, where the weight-bearing pelvis and lower spine routinely work to support and adjust for minor (but not uncommonly, more) unlevelness of the supporting pelvic structure. We start this process once we begin to walk as toddlers, and routinely develop a neuro-muscular and bio-mechanical balance within a very short time.
It is truly unfortunate that our modern lifestyles have resulted in such widespread reduction of dynamic movement in our lives (see also Bog 2--Exercise). The negative effects of decreased activity have coincided with longer periods of (static) postures involving Flexion stress (i.e., sitting for 8-14 hours/day). Flexed postures --prolonged and repeated--can result in peculiar stress and even injury to discs and ligaments that control or affect movement.
Low-level pain and/or injury can result in variable degrees of para-spinal muscle tightness, which can fundamentally interfere with, or at least alter, an otherwise well-compensated lumbo-pelvis, and become an obstacle to healing or resolution. Instead of "ease" of weight-bearing movement, there occurs "dis-ease" of some sort, for what can be a very long period of time.
Sustained static postures can also result in muscle group tightness in other regions of the body, such as painful conditions of the upper back, arms, and neck (see also Blog 4.2: "Tech. Neck").
So, if your work and/or lifestyle involves extended periods of sitting (flexion stress), I strongly recommend you take measures to reduce this potentially injurious posture. Awareness is one key element. Diligence with incorporating exercise and/or stretch sessions that involve extension (backward bending)into your daily and weekly routines can be very helpful. If you already have symptoms of low back pain, various extension stretches many times a day would be necessary to counteract / address the accumulated and deleterious effects of flexion stress on your body and posture (see also Gen.Info: Therapeutic Postures- Extension). The longer you have had back pain, the longer it will be necessary to do extension stretches for you to benefit in any way.
I'm busy working on my blog posts. Watch this space!