Where your gait might break down.

Gait appears most robust to weakness of hip and knee extensors, which can tolerate weakness well and without a substantial increase in muscle stress. In contrast, gait is most sensitive to weakness of plantarflexors, hip abductors, and hip flexors. – van der Krogt

In the past few weeks I have shared my thoughts on some articles regarding low back paraspinal musculature fatigue and the subsequent effects on motorneuron pools, specifically excitability of the soleus and quadriceps. These shared thoughts are from recent papers in the literature (search the blog over the last week). These effects are suggested to indicate a postural response to preserve lower limb function. In other words, as paraspinal fatigue set in, lower extremity muscle compensation ramped up to sustain postural locomotion demands.  Obviously, one should think this a step further and translate it all into questions of assessment of ankle dorsiflexion (ankle rocker) and control of progressing knee and hip flexion when pertaining to these muscles. The issues of stability and mobility should heighten. The one big problem in these studies, and you have even likely had these thoughts during your clinical examinations, is that one cannot truly fatigue one muscle group alone especially during activity, nor can one assess a single muscle group during manual testing. Luckily we have EMG testing capabilities in this day and age and we can more easily look into the function and reaction of a muscle and its’ direct response reactions. 

Today I have an article by van der Krogt that we read long ago, but that which one of our readers brought back into our wheelhouse.  This is pretty amazing stuff.

“This study examines the extent to which lower limb muscles can be weakened before normal walking is affected. We developed muscle-driven simulations of normal walking and then progressively weakened all major muscle groups, one at the time and simultaneously, to evaluate how much weakness could be tolerated before execution of normal gait became impossible. We further examined the compensations that arose as a result of weakening muscles. Our simulations revealed that normal walking is remarkably robust to weakness of some muscles but sensitive to weakness of others. Gait appears most robust to weakness of hip and knee extensors, which can tolerate weakness well and without a substantial increase in muscle stress. In contrast, gait is most sensitive to weakness of plantarflexors, hip abductors, and hip flexors. Weakness of individual muscles results in increased activation of the weak muscle, and in compensatory activation of other muscles. These compensations are generally inefficient, and generate unbalanced joint moments that require compensatory activation in yet other muscles. As a result, total muscle activation increases with weakness as does the cost of walking.“-van der Krogt

So, if your client comes in with knee, hip or ankle pain and a history of low back pain, you might want to pull out these articles. You may want to consider which muscles are, according to this article, most robust and sensitive to weakness. Remember what I mentioned when i reviewed the soleus article ? I mentioned that the reduced ankle dorsiflexion range may be from a soleus muscle postural compensation reaction to low back pain. Today’s article seemed to confirm that this muscle group is sensitive to weakness. In today’s discussion, not only is the impairment of the hip ranges of motion or control of the knee (from quadriceps adaptive compensation) possibly related to low back pain, in this case, paraspinal fatigue but it may be a muscle group robust to weakness which is a darn good thing when the paraspinals go to nap.

Sometimes the problem is from the bottom up, sometimes it is from the top down. It is what makes this game so challenging and mind numbing at times. If this is all too much for you, in teasing out this quagmire of a system, just throw corrective exercises at your client and hope for the best. What is the worst that can happen if you get it wrong ? Stronger compensations on already present compensations … . . why not, it is good for return business (insert sarcasm emoticon).  But, lets be honest, if it was easy everyone would be doing it the right way. But the truth is that it is a long journey, and we are on the same bus of discovery with you all. 

Dr. Shawn Allen, one of the gait guys.

Reference:

Gait Posture. 2012 May;36(1):113-9. doi: 10.1016/j.gaitpost.2012.01.017. Epub 2012 Mar 3.How robust is human gait to muscle weakness?van der Krogt MM1, Delp SL, Schwartz MH.

The effect of lower extremity fatigue on shock attenuation during single-leg landing.

Thank goodness the body can compensate. Here is a perfect example of this discussed in this study.
“ … it has been shown that a fatigued muscle decreases the body’s ability to attenuate shock from running. The purpose of the study was to determine the effect of lower extremity fatigue on shock attenuation and joint mechanics during a single-leg drop landing.”
This study suggests that as one part fatigued, the joint and muscle strategies elsewhere in the limb made up for it.
“Hip and knee flexion increased and ankle plantarflexion decreased at touchdown with fatigue. Hip joint work increased and ankle work decreased.” The results suggested that the lower extremity is able to adapt to fatigue though altering kinematics at impact and redistributing work to larger proximal muscles.

The effect of lower extremity fatigue on shock attenuation during single-leg landing. Clin Biomech (Bristol, Avon). 2006 Dec;21(10):1090-7. Epub 2006 Sep 1.
Coventry E1, O’Connor KM, Hart BA, Earl JE, Ebersole KT.
http://www.ncbi.nlm.nih.gov/pubmed/16949185

Rewiring.

The peripheral and central nervous systems are functionally
integrated regarding the consequences of a nerve injury: a
peripheral nerve lesion always results in profound and long lasting
central modifications and reorganization. (Kaas, 1991)
Does there need to be a lesion though ? A functional lesion will force changes just like an ablative lesion. Altered gait that persists from a sprained ankle or a painful knee will force central modifications and reorganization. This is why resolution of pain and aberrant function is critical. If you rehab to 80% you leave 20% on the table and that gets rewired into the system as the new norm. Remember, the entire system is watching, learning, adapting and rewiring all the time. This is why you must have a team in place to resolve all, if possible, of your client’s deficits. If you leave 20% of a problem on the table, and add endurance and strength to the “80%resolved:20%remaining”, you reorganize the central nervous system with that as the assumed norm moving forward. From this point forward, this is the architecture that all new patterns and forms are built from.  This sets up for long term rewiring of all of the connected parts, from motor, sensory, visual, gait, proprioceptive, vestibular and the list goes on and on. If you have ever wondered how a client can have so many areas of pain and dysfunction you might want to go back into their history and ask them if there was a single injury or event that occurred after which all their new problems started to stack up. 

If you are a gait analysis junkie, remember this principle above. All of the things you see in a person’s gait are not unconnected in many cases.  Much of what you see is a compensation around their problems, not the actual problem. 

Remember this principle: the peripheral nervous system attempts to repair by regrowth, the central nervous system attempts to repair by re-routing and reorganizing.

Dr. Shawn Allen

Is the “normal foot” normal ?

IF one foot is not normal, the other one cannot be “normal” either.  This is a blog post about symmetry, sort of.

This article just sort of seemed silly to us.

Imagine having a stone in one shoe and walking around in that shoe. Obviously you are gonna alter weight bearing in that shoe to avoid the pain and pressure of the stone. That means that the normal gait cycle of that foot/leg will be distorted somehow, the timed events of the gait cycle will be distorted and even likely the duration of the stance phase, heck, even plantar pressures will be changed.  Thus, the apparently “normal” foot on the opposite side will have an altered loading response and challenge because it will be receiving anything but normal biomechanics from the “stoned” shoe/foot.  Adaptation and compensation will have to occur, and not just in the “normal” foot, the entire body. 

Take another example, a sprained ankle. The brain will abbreviate the painful stance phase and abrupty depart the foot and thus create premature loading on the healthy foot, likely into mid-midstance which is usually met by midfoot strike and catching the body load with the quad thanks to abrupt knee flexion rather than early midstance with glute control during the loading response.  

Thus, if one foot is abnormal, there is just no way the so-called “normal” foot will be unaffected.  As this study suggests, the normal foot will have altered pedobarographic measurements.  Maybe we are missing the point here, but we suppose the words “relatively normal” or an “expected normal” should have been used. Yes, we may be splitting hairs here and discussing a relatively moot point, but our purpose was to just describe that since the two limbs are attached to the same body, if one side is not normal, a compensation has to occur in the other limb.  There is no other option.  We talk more about this concept in podcast 75 which will launch next week.

Shawn and Ivo, the gait guys

The contralateral foot in children with unilateral clubfoot, is the unaffected side normal?

http://www.gaitposture.com/article/S0966-6362(14)00523-2/abstract

Highlights

  • Pedobarographic measurements of unilateral unaffected clubfoot are not same as normal controls.
  • The unaffected foot should not be referred to as normal, nor should it be used as a control.
  • Timings of initiation of stance differ significantly between normal and unaffected clubfeet.
  • Unaffected clubfoot accumulates differences from normal feet due to maturation of gait with age.

Abstract

“Significant differences were identified between the unaffected side and normal controls for the pressure distribution, order of initial contact and foot contact time. These differences evolved and changed with age. The pedobarographic measurements of patients with clubfoot are not normal for the unaffected foot. As such the unaffected foot should not be referred to as normal, nor should it be used as a control.”

What is Visual Parallax and how does it affect gait analysis? : Is your video gait analysis really telling you what you think it is telling you ?

We recently were asked by a student at a physical therapy school to help with a teaching case. They asked us to look at a gait video to assist in outlining some things in the case.  Here was our response.
“Hello Jane Doe

We are happy to look at the video for you so you and others can learn.

Just please know, as we say all the time here on the Gait Guys, that without an examination that what we are all seeing is not the problem rather the persons compensatory strategy around the dysfunctional parts.

Plus, video negates binocular parallax viewing so things that would stand out in in a exam where we are physically present will be masked quite a bit in/on video or on a computer screen. We try to minimize these visual losses by getting multiplanar gait video views (sagittal from front and back and coronal from left and right sides) but even these will not fill the visual gap from transferring data from 3D to 2D and then trying to interpret a 3D answer from the 2D.  But it is the best one can do with our technology today unless you use a body suit sensor system, and then you still have the limitations of “what you see is not the problem, its their compensation” so one still needs the physical exam to put the puzzle together.

Here…….. read this if you are wondering what we mean.

*This blog article (link below) which we wrote 18 month ago is the heart of what we wanted you to read today. Visual parallax and binocular vision both need to be understood so that you can better understand why what you see on your gait analysis video might not be what  you think you are seeing. Seeing is one thing, knowing what you are seeing is another, knowing the limitations and the “why” of what you are seeing is yet another.

So, we can tell you what we see………but without an exam we cannot tell you with great accuracy why you are seeing what we see.

that make sense ?”

best
shawn and ivo

What is Visual Parallax and how does it affect gait analysis? : Is your video gait analysis really telling you what you think it is telling you ?

We recently were asked by a student at a physical therapy school to help with a teaching case. They asked us to look at a gait video to assist in outlining some things in the case.  Here was our response.
“Hello Jane Doe

We are happy to look at the video for you so you and others can learn.

Just please know, as we say all the time here on the Gait Guys, that without an examination that what we are all seeing is not the problem rather the persons compensatory strategy around the dysfunctional parts.

Plus, video negates binocular parallax viewing so things that would stand out in in a exam where we are physically present will be masked quite a bit in/on video or on a computer screen. We try to minimize these visual losses by getting multiplanar gait video views (sagittal from front and back and coronal from left and right sides) but even these will not fill the visual gap from transferring data from 3D to 2D and then trying to interpret a 3D answer from the 2D.  But it is the best one can do with our technology today unless you use a body suit sensor system, and then you still have the limitations of “what you see is not the problem, its their compensation” so one still needs the physical exam to put the puzzle together.

Here…….. read this if you are wondering what we mean.

*This blog article (link below) which we wrote 18 month ago is the heart of what we wanted you to read today. Visual parallax and binocular vision both need to be understood so that you can better understand why what you see on your gait analysis video might not be what  you think you are seeing. Seeing is one thing, knowing what you are seeing is another, knowing the limitations and the “why” of what you are seeing is yet another.

So, we can tell you what we see………but without an exam we cannot tell you with great accuracy why you are seeing what we see.

that make sense ?”

best
shawn and ivo

Are you a Gait Troglodyte ? Are you sure ?

Are you a Gait Troglodyte ? Are you sure ? You might want to read on.

Most of us are all still in a cave and unacquainted with some of the affairs of the world. Some of us may find ourselves behind the times when it comes to GMO foods, social media, computers and the internet, smart phones while others may be behind on world issues and politics. Heck, some of us have never even seen “Ancient Aliens” on the History Channel !  It is hard to keep up with everything in this fast paced changing world. Something has to give for each of us and so we pick our poison and decide what it is that we are going to have to remain behind on when it comes to the learning curves of the world. And this is alright, but you have to first admit your “back of the pack” and “still living in a cave” type status on the issues and take some ribbing when acknowledging your limitations.  Failing to admit these inevitable shortcomings while pretending that you are still running with the pack can be a real problem. Not only are you faking yourself out but you may be deceiving those that you attempt to help.

Understanding gait, truly understanding it, is a monumental undertaking. This is why there are just no vast resources on it unlike other things in healthcare. Try going to PubMed and type in “arm swing”, you will see 318 articles. Try “pronation”, 2900 articles.  Now try “heart”, 1 million+ articles.  You get the point. Research is behind on gait, and thus our understanding of it is also poorly reflected in functional medicine and  human bodywork.  We are collectively gait troglodytes, living in stereotypical caveman times when it comes to gait.  Sure there are some good books like Perry’s text, or Michaud’s landmark work but there is a void on gait work and research. Human locomotion via gait (walking and running) is a small and poorly understood component by many. It is much the reason why we started The Gait Guys and began writing daily for over 600 days on gait issues. Little did we know that the door we had opened would continue to swing so wide and encompass so many other aspects that feed into human gait.

One of the aspects that worries us the most these days is the growing volume of “functional” work that is going on in the world of therapy and training.  There is a very important and critical place for this work and we fully admit that everyone needs to be on board with all of the great work that the leaders are teaching. What worries us is the apparent lack of integration of this work into gait assessment, gait therapy, and flawed gait neuro-biomechanics. Once again gait is not getting the pulpit it deserves. Yes, flaws in the functional screens and assessments need to be brought to light and remedied because they can impact bipedal locomotion but, the pendulum swings both ways. Gait can often be a cause of these functional problems that show up on the screens and assessments. If one fixes the functional pattern problems and the gait pattern is not restored then either the dysfunction will return or a new undesirable pattern will be generated. There needs to be more gait understanding and assessment from us all. Gait needs retraining as well, it is as much of a functional pattern as any other, if not more.  Gait deserves a pulpit as well.  Human assessment is clearly a two way street and it is not always clear who is the chicken and who is the egg. The problem may be that when gait does have its pulpit to speak from, who is the speaker ? A gait troglodyte or an expert ?

There will be folks who say we are over thinking this issue. There will be some who are offended. There will be some who cheer. There are some that will say “it will all come out in the wash” once the functional patterns are corrected elsewhere. They are wrong, it just is not that simple. Next to breathing, gait may be the second most compromised and corrupted functional pattern that humans express thousands of times daily. So, it is time to get busy.  It is time to peel off your Gait Troglodyte cloak and step into a 3 piece suit when it comes to understanding and interpreting gait.  If you are working in the world of human movement, locomotion, training, rehab and human biomechanics this is your next challenge.  Lets face it, we can either continue to walk around with our 10 year old flip phone understanding of gait or we can step up to a smart phone understanding of gait.  It is up to you, but know where you are and know your limitations. So be honest with yourself and your next client the next time you assess their gait. Be sure to ask yourself after seeing something that just doesn’t seem right in their gait, is what you see really what you are seeing ? Is that really what is wrong ? Or is it a compensation ? Do you know enough to see things for what they really are ?

Shawn and Ivo, The Gait Guys. 

We may not be Gait Troglodytes……. but some accuse us of living in a cave none the less.  However, if you have seen our cave, you will know it looks much like Bruce Wayne’s Batcave.  It isn’t your everyday cave.