Stacking of the joints, and something that can go wrong when they don’t stack well.
Here is a short, sweet and simple case to open up some thoughts. We have read on several occasions of people making changes to arm swing as a solitary independent issue. Arm swing, when aberrant, is quite often a compensatory change to something else. It is quite often a problem in the opposite lower extremity. We will be doing a 1 hour teleseminar in 2 weeks on www.onlinece.com on the topic of arm swing. Why don’t you come and join us ?
This photo proves our point. It is clear to anyone that the right arm is far too abducted , yet it should make one question as to whether it is a product of the “failure to stack” the left lower limb. One should easily see that the right hip has drifted beyond the perpendicular line of the left foot and that we are witnessing somewhat of a Trendelenberg presentation. The left hip should be over the left foot. We classify what we see here however, as “stance phase” frontal plane sway. It is a POSSIBLE product of many things, but remember that what you see is a compensation around a functional or ablative problem, and not the actual problem most of the time. One could easily hypothesize that the left gluteus medius is weak or that the left abdominals are frontal plane weak but these are only the two major assumptions most people make. Remember one of our cardinal rules, when the foot is on the ground the glutes are in charge, and when the foot is in the air, the abdominals are in charge. So, do not forget to look at the right sided abdominal component here as well. How about foot and ankle stability ? Something is causing her frontal plane drift. It is your job to find it and correct it, not the arm swing (unless you determine it as the cause). But it is not your job to guess !
Is it luck or predictable fact that the left pelvis is left frontal plane deviating and that the right arm is right frontal plane deviating ? Not in our opinion, she is trying to maintain balance and symmetry during power production. Balance maintenance comes from many areas.
Because of the neurologically embedded crossed extensor reflex and cross crawl response that permeates all human locomotion, anything that changes one of the limbs, whether it be a direct limb issue or something to do with the stabilization of the limb can impair and change locomotion, motor pattern choices and programming.
So, be careful where you make your demanded changes in your clients and your athletes. If you are guessing you are playing with fire and potential injury. The patterns are centrally generated and not by conscious choice, and hence they should not be completely remedies by the athletes conscious choice. According to Zehr, “Although the strength of coupling between the legs is stronger than that between the arms, arm and leg movements are similarly regulated by CPG activity and sensory feedback (e.g., reflex control) during locomotion.” (Neuroscientist. 2004 Aug;10(4):347-61. Regulation of arm and leg movement during human locomotion.Zehr EP, Duysens J. Rehabilitation Neuroscience Laboratory, University of Victoria, BC)
There is alot more to this topic, but you will just have to join us in two weeks on www.onlinece.com. Third Wednesday of every month, 7pm central time, that is where you will find us !
shawn and ivo,
the gait guys