“For every action there is an equal and opposite reaction” =  Newtons 3rd Law of Motion



If we take Newtons 3rd law of motion and apply it to walking (aka gait) then we can begin to understand how our body must absorb a force equivalent to our own body weight each time we take a step.  This ground reaction force is the reason why the phase of gait known as the “heel strike” is so important.  It sets the table to disperse forces throughout the body with every step, as nature intended.


During initial contact between our foot and the ground it is important that the lateral aspect of the calcaneus (heel bone) make initial contact.  As we look at the anatomy of the calcaneus below we see how it has evolved to strike laterally and roll medially to absorb ground reaction force.  This sets the stage for efficient pronation during suspension phase, which sets the stage for efficient supination during propulsion.  The importance of these phases will be covered in my next blog when I vent about the overprescription of orthotics.



Posterior view of the calcaneus of a right foot


During heel strike what is know as our deep longitudinal subsystem (DLS) concentrically contracts after being eccentrically loaded during the swing phase of gait.  This subsystem is extremely important in the efficient distribution of ground reaction forces during heel strike.  What happens if there is an inefficiency within this subsystem?  One can bet that weight bearing joints within the system are going to be forced to deal with increased forces and loads.  Hips, knees, low back, maybe even as high as the neck!  How this presents as a clinical pain presentation can vary quite a bit.  Allow me to share an interesting case that recently came into my office…




A 17 year old girl presented with right lower quadrant abdominal pain of one year duration.  Blood tests and imaging were all negative for the usual suspects so her MD referred her to me thinking her pain must be musculoskeletal in nature.  This particular patient was in excellent shape as she had been a dancer prior to a concussion she suffered a couple years back.  It is my assumption that the concussion contributed to rigidity throughout her system which affected the way her body absorbed the ground reaction forces created with each step she took.  I made this assumption because her lumbo-pelvic-hip rotation was restricted and her pain was aggravated by walking ONLY.  To be specific, you guessed it, during heel strike.


Using Anatomy in Motion (AiM) we explored her heel strike in 3 dimensions and found her lumbar spine to be eccentrically loading during this phase, completely bypassing her deep longitudinal subsystem.  My NKT® assessment complimented this finding as her erector spinae/thoracolumbar fascia was compensating for her hamstrings.  Why this dysfunction presented as lower right quadrant abdominal pain is something I cannot explain.  What I can tell you is that as her body became comfortable exploring heel strike with AiM, she began to feel her  DLS eccentrically load.  This created immediate pain relief while walking and within a week of doing her exercises the pain had gone from 6/10 with every single step to a 1/10.  All by retraining the DLS during heel strike.


Aside from this patient I have seen a variety of pain presentations that were all corrected or at least helped significantly by retraining the DLS during heel strike.  Low back pain, hip pain and even neck pain.  Sometimes manual therapy is required to allow the body to access efficient use of this subsystem, sometimes a little body awareness is all it takes.  Either way, once you show the body an efficient alternative to its painful movement pattern it tends to reward you by choosing that option over the dysfunctional one.  It’s almost like the body is hard wired to walk efficiently until old injuries and repetitive tasks screw everything up and create compensation city.  The good news is the body is phenomenal at adapting.  Provide it with the correct sensory input and it will respond with the optimal motor output.  


If your pain is only temporarily improved with treatment (Chiro, Physio, Massage, etc.) then you might be unraveling changes made during treatment in your gait patterns.  It might be time to change the way you move.