* Important: (this is a continuation of yesterday’s post, December 7th. You must read Part 1 from yesterday to have any chance to make sense to today’s post.)
So, we are back to looking at limb swing again. It is important for you to realize, as put forth in
Huang et al in the Eur Spine Journal, 2011 Mar 20(3) “Gait Adaptations in low back pain patients with lumbar disc herniation: trunk coordination and arm swing.”
that as spine pain presents, the shoulder and pelvic girdle anti-phase (as in drawing above) begins to move into a more “in-phase” favor. Meaning that, the differential between the upper torso twist and pelvic twist is reduced (in the drawing above the lines will laterally converge). IF this anti-phase is reduced then arm swing should be reduced (half truth, this is a topic for anther time). The central processing mechanisms do this to reduce spinal twisting, because reduced twist means reduced spinal motor unit compression and this hopefully leads to less pain. This also means reduced thoracic mobility unfortunately (think about this the next time a shoulder assessment test directs you to the thoracic spine and rib cage mobility). The consequence to this reduced spinal rotation is reduced limb swing. Think about this next time you see someone, a runner patient or athlete, with reduced arm swing especially on one side. Furthermore, according to
Collins et al Proc Biol Sci, 2009, Oct 22
“Dynamic arm swinging in human walking.”
normal arm swinging requires minimal shoulder torque, while volitionally holding the arms motionless requires 12 % more metabolic energy, proving that there are both active and passive components to arm swing. Collins also discovered that among measures of gait mechanics, vertical ground reactive moments are most affected by arm swinging and increased by 63% without it. Wow, 63% !
So, it is all about efficiency and protection. Efficiency comes with fluid unrestricted movements and energy conservation but protection has the cost of wasting energy and reduced mobility through a limb(s) and spine.
Now, digest all of this and we will talk about primitive and modern day man next time…….. think about it…. carrying spears and briefcases, or runners carrying a water bottle for that matter. There is more to this arm swing thing than we are letting on here, but you have to digest this first. Please, take the time to re-read this and yesterday’s post and really “get it” because this is going to likely get a bit complicated. But if you take the time to digest this you will never look at an athlete or patient the same again. Your patient assessments will grow deeper and have more clarity.
There is a reason that in our practices we often assess and treat contralateral upper and lower limbs. If you are paying attention, these in combination with the unilateral loss of spinal rotation or lateral flexion are the things that need attention. And for those out there that do not think that the foot is important (we can think of at least one industry guru who thinks it is a “non-factor”), think about this: When there is insufficient hip rotation unilaterally you can regain some of the loss through increased foot pronation unilaterally. The problem with this is that you compromise the swing phase on the contralateral side when you do that and quire often create an abductory foot twist on the hyperpronated side (due to firing of the medial head of the gastroc to invert the foot and assist in supination). However, if you are trying to walk in a straight line from A to B, you also have yet another option, a subconscious option of putting a axial spin through the whole body, some call this pelvic distortion patterning or pelvic obliquity.
OK, that should keep your heads swimming for awhile until the next post on arm swing. It is not as simple as telling your athlete to swing one arm more, or to stop pulling it across their body; they need to do those things, it is called a “compensation”. Merely addressing that locally is such a crime. If you are seeing an arm swing change, you would be foolish not to look at the opposite lower limb and foot at the very least, and of course assess spinal rotation, thoracic extension and lateral bend, …..all spinal functions for that matter. For your neuro nerds, remember the receptors from the central spine and core fire into the midline vermis of the cerebellum (one of the oldest parts of our brain, called the paleo cerebellum); and these pathways, along with other cerebellar efferents, fire our axial extensor muscles that keep us upright in the gravitational plane and provide balance or homeostasis which the ancient Chinese called Yin and Yang.
Simple log-rolling type patterns on the floor or the spine assessment pattern of your preference will likely show a difficulty or asymmetry unilaterally. Think of the neurological implications of long term unilateral asymmetry, altering neuronal plasticity, and altering our movement patterns (and thus our compensations). Make sure to couple this with specific muscle testing to be as clear as you can. Too many folks rely solely on movement assessments but that can catch you in a lie quite often because you could be seeing a compensation.
Yup, we are The Gait Guys….. we have been paying attention to this stuff long before the functional movement assessment programs became popular. If you just know gait well enough, one of the single most primitive patterns other than crawling and breathing and the like, you will understand why you see altered squats, hip hinges, shoulder ROM screens etc. You must have a deep rooted fundamental knowledge of the gait central processing and gait parameters. If you do not, every other screen that you put your athlete or patient through might have limited or false leading meaning.
Shawn and Ivo … combining almost 40 years of orthopedics, neurology, biomechanics and gait studies to get to the bottom of things.
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