Random thoughts on gait (and other) motor patterns …….
It is quite possible and reasonable to assume that a motor pattern is a natural mechanism for joint and multi-joint protection. Consciously trying to alter a motor pattern is likely to drive an improper pattern or one that is deemed unstable by the brain.
Scenario: client has right foot spun externally into the frontal plane by 15 degrees more than the opposite side.
In this scenario, this could be the reason why merely attempting to turn inwards a right foot that has drifted its way in time outwards does not hold even though it is clearly a deviation from symmetry. It is likely the fact that the brain, in such a scenario, has calculated that there is not sufficient stability in a more neutral symmetrical foot progression angle and thus has found the necessary stability in a more turned out position. As we have always said, subconsciously turning the foot outwards helps to cheat into the frontal plane, likely because that plane is less stable with a neutral foot and with the foot “kickstand” turned out, stability is achieved. Thus, engaging the foot better in that plane gives the brain and body the perceived and actual stability that it feels it needs to more naturally provide joint or multi-joint stability. That is not say this is optimal biomechanically for best-case function, but in this picture with all the parts assembled in their present functional ability, this is the optimal pattern. It is however fraught with risks and probable consequences, and these are what may play out in time to develop into an injury. It is safe to say that the central nervous system (brain etc) will only allow one to place the body and its limbs into positions of perceived stability. We say “perceived” because there are parameters that can fool the brain. For example, the peripheral neuropathy numbness and loss of proprioception from advancing diabetes can lead to faulty input from the peripheral sensory receptors thus procuring a miscalculated decending motor pattern, and possible placement of the limb in a less than optimal position. Do not be mistaken, the brain thinks this is an optimal limb placement, but it does not know it did so on faulty sensory information. The brain assumes that the information is accurate. This is why you see such horrible fragmented unstable and waivering gait in advancing diabetics. Their feet can get so numb that there is simply insufficient sensory information to develop any semblance of a clean gait motor pattern. The same goes with an ACL deficient knee. The ACL is a major proprioceptor, a major driver of joint position sense. It is not nearly as detrimental to the motor pattern as advanced peripheral neuropathies but it has a similar effect, just muted. And in many cases this can be worse. In a high level athlete, this possible lack of obvious awareness of key proprioception / joint position sense can let the athlete get into a potentially dangerous loading position where the joint is at higher risk. Where as a full blown neuropathy patient knows that such a task is impossible.
Just some random thoughts…….. internal cortical ramblings of gait crazed madness.
Happy Thanksgiving everyone !
Shawn and Ivo