Effects of prior hamstring injuries

Previous hamstring injury is associated with altered biceps femoris associated muscle activity and potentially injurious kinematics.

“Previously injured athletes demonstrated significantly reduced biceps femoris muscle activation ratios with respect to ipsilateral gluteus maximus, ipsilateral erector spinae, ipsilateral external oblique, and contralateral rectus femoris in the late swing phase. We also detected sagittal asymmetry in hip flexion, pelvic tilt, and medial rotation of the knee effectively putting the hamstrings in a lengthened position just before heel strike." 

The biomechanics of running in athletes with previous hamstring injury: A case-control study. C. Daly1, U. McCarthy Persson2, R. Twycross-Lewis1, R. C. Woledge1,† andD. Morrissey1,

“Neural circuits linking activity in anatomically segregated populations of neurons in subcortical structures and the neocortex throughout the human brain regulate complex behaviors such as walking, talking, language comprehension, and other cognitive functions associated with frontal lobes.” 1

We also found this interesting quote from Science Daily on this topic of complex sensory motor behaviors and on the varying information on central pattern generators.

ScienceDaily (June 3, 2012) — “A new finding that motor cortex is a dynamic pattern generator upends existing theory with broad implications for neuroscience.”

“Maybe it is actually easier to understand than we thought. A new paper presents some compelling evidence that the motor cortex, rather than being command central, is more like a part of the machine, sending rhythmic signals down the spinal cord to orchestrate movement.”

"The electrical signal that drives a given movement is therefore an amalgam — a summation — of the rhythms of all the motor neurons firing at a given moment.” This is of course monitored (and modified) by one of our best friends, the cerebellum. 2

The cortex is where movement begins and where it ends; from areas 4, 4s and 6 in the precentral gyrus of the brain’s frontal lobe, down the spinal cord and out to the muscle through the peripheral nerve.   It is also where the information from the body’s receptors feed back,  to give updates on where the body parts are in space (proprioception) and how they are doing functionally (comparing information about length, tension, etc).  It is about sensory and motor function.  Motor function is based on sensory input.  Good motor function is based on good sensory information. It is a subtle, beautiful, intricate symphony.  And when one part goes wrong, the whole system can be thrown off.  

Here is an example we sometimes use in our lectures and with our patients to make this point clear.  Imagine an orchestra playing Beethoven’s beautiful Ode to Joy, a choral symphony for orchestra.  Now imagine one of the musicians begins to play off key. In time, the musicians sitting around that musician who are most locally influenced by that off tune musician, soon become irritated and have troubles playing “in tune”. In time, if not rectified, the whole orchestra could be corrupted and being to take that lead as well.  Hard to believe, but it makes the point that all it takes is one piece not playing well to change the outcome. Similar analogy, all it takes is one weak muscle or one painful joint and the outcome is skewed away from the optimal outcome and in time local dysfunction and compensation becomes an all encompassing compensation. The body’s function and operation, when proper, is an orchestra and orchestration with each piece doing a local job with a more global contribution to the bigger job. When all pieces come together appropriately it creates a symphony of flawless, effortless movement as seen in the video above.

Shawn and Ivo, the gait guys


1. Front Syst Neurosci. 2014 Feb 13;8:16. eCollection 2014. Cognitive motor interactions of the basal ganglia in development .  Leisman G1, Braun-Benjamin O2, Melillo R3.

Do you know your stuff? Would you correct this child’s gait ? Give them orthotics, exercises, force correction, leave them alone ? 

Is he Internal Tibial torsioned ? Is he “pigeon toed” ,if that is the only lingo one knows, 😦  Does he have femoral torsion ?  A pronation problem locally at the foot or an internal spin problem through the entire limb ? Or a combination of the above ? 

What’s your solution?

It MUST be based on the knowledge necessary to fix it, not the limits of YOUR knowledge. You can never know what to do for this lad from his gait evaluation, no matter how expensive your digital, multi-sensor, 3D multi-angle, heat sensor, joint angle measuring, beer can opening, gait analysis set up is. You can never know what to do for this lad if you do not know normal gait, normal neuro-developmental windows, normal biomechanics, know about torsions (femoral, tibial, talar etc), foot types etc.  It is a long list.  You cannot know what to do for this kid if you do not know how to accurately and logically examine them. 

Rule number 1. First do no harm.

If your knowledge base is not broad enough, then rule number one can be easily broken ! Hell, if you do not know all of the parameters to check off and evaluate, you might not even know you are breaking rule number one !  If everything looks like a weak muscle, every solution will be to “activate” and strengthen and not look to find the source of that weakness.  Muscles do not “shut down” or become inhibited because it is 10 minutes before practice or because it is the 3rd Monday of the month. You are doing your client a huge disservice if you think  you are smarter than their brain and activate muscles that their brain has inhibited for a reason. What if it were to prevent joint loading because of a deeper problem ?  If every foot looks flat and hyper pronated, and all you know is orthotics or surgery or shoe fit, guess what that client is prescribed ? If all you see is torsions, that is all you will look to treat. If all you see is sloppy “running form” and all you know is “proper running form” forcing your client into that “round peg-square hole” can also lead to injury and stacking of compensation patterns.  

One’s lack of awareness and knowledge, are one’s greatest enemies. If you don’t know something exists, because you’ve never studied or learned it, how can you be aware of it ? If you’re not spending enough time examining a client, you might not be aware of an issue even though you may be knowledgeable about the issue.
One must have both awareness and knowledge. One must also be aware that compensations are the way of the body. What you see is not your client’s problem. It is their strategy to cope.

Are you helping your client ? Hurting them ?  Adding risk to their activity ? Are you stepping beyond your skill set ?  

Rule Number 1: First do no harm. 

Shawn and Ivo

PS: we will get to this case another time, we just wanted to make a point today about the bigger problems out in the world.

the gait guys

Human gait is cyclical. For the most part, when one limb is engaged on the ground (stance phase), the other is in swing phase. Before we continue, you should recall that there is a brief double limb support phase in walking gait, that which is absent in running gait. Also, we wish to remind you of our time hammered principle that when the foot is on the ground the glutes are heavily in charge, and when the foot is in the air, the abdominals are heavily in charge.  

For us to move cleanly and efficiently one would assume that the best way to do that would be to ensure that the lower 2 limbs are capable of doing the exact same things, with the same timing, same skill, same endurance and same strength. This goes for the upper 2 limbs as well, and then of course the synchronizing of the 4 in a cohesive effort. For this clean seamless motor function to occur, one must assume that there would be no injuries that had left a remnant mark on one limb thus encouraging a necessary compensation pattern in that limb (and one that would then have to be negotiated with the opposite limb as well as the contralateral upper or lower limb).  For example, when right ankle rocker (dorsiflexion) is impaired, early heel departure will occur and hip extension will be limited. An alteration in right glute function will most likely follow.  One could theorize that the left step length (the length of measure from right heel strike through to left heel strike) would thus be shortened. This would cause a premature load onto the left limb, and could very well force the left frontal plane to be more engaged than is desirable. This could lead to left core and hip frontal plane weakness and compensation patterns to be generated (ie. right arm abduction. One can see all of these components in the photo above, and in this case here). It could also lead to a pelvic distortion pattern which would further throw off the anti-phasic nature of symmetrical and efficient gait.  To complicate the cyclical scenario, the time usually used to move sagittally will be partially used to move into, and back out of, the left frontal plane. This will necessitate some abbreviations in the left stance phase timely mechanical events. Some biomechanical events will have to be abbreviated or sped through and then the right limb will have to adapt to those changes. These are simple gait problems we have talked about over and over again here on the gait guys blog. (Search “arm swing” on our blog and you will find 45 articles around this topic.) These compensation patterns will include expressed weaknesses in various parts of the human frame as part of the pattern, and merely fixing those weaknesses does not address the right ankle rocker problem. Fixing said weaknesses merely encourages the brain to possibly continue to perpetuate necessary tightnesses in other muscles and engrain the compensations (challenges to mobility and stability) further or more complexly.  It is easy to find something weak, it takes a sharp brain to find the sometimes silent sparking event. Are you able to find the problem in this never ending loop of compensations and find a way to unwrinkle the system one logical piece at a time, or will you just chose to strengthen the wrinkled system and hope that the new strength on top of the compensations is adequate for you our your client ? One should not be forever sentenced to daily or weekly rehabilitative sessions/ homework to negate and alleviate symptoms, this is a far more durable machine than that. Fix the problem.

Now, lets add another wrinkle to the system.  What if there were problems before any injuries ?  Meaning, what if there were problems during the timely maturation and suppression of the primitive reflexes ? Or problems in the timely appearance or maturation of postural reflexes? A problem in these areas may very well result in a central or peripheral nervous system malfunction and a representation of such in one’s movement and gait.  That is a larger discussion for another time.

There is a reason that in our practices we often assess and treat contralateral upper and lower limbs as well as to address remnants from old injuries whether they are symptomatic or not. This is a really tough puzzle and game you are playing. For example, when there is insufficient hip internal rotation unilaterally you can regain some of the loss through increased foot pronation unilaterally, but at a consequence to both the local and global pictures.  Remember, most of the time you are trying to walk in a straight line from A to B and if the parts are not symmetrical you have many options to compensate. 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”. It is often not as simple as finding an impaired Rolling Pattern and driving it back to symmetry, in doing so, you may have just added strength and skill to a compensation.  Merely addressing things locally can be 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, lateral flexion and hinging as well as core mobility and stability.  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.  So, those need assessed and addressed as well.  

Or, if this is too much thinking for you, … you can just train harder and get stronger . .  . in all your compensation patterns, after all, it is easier than figuring out why and how that right ankle started the whole mess, if in fact that is even the first piece of the puzzle.

Welcome to the matrix.

shawn and ivo, the gait guys

How injury and pain reorganize the brain.

Gait, Arm Swing and Reorganizing the Brain

When we injure a body part there is a price to pay, how expensive it will be is entirely up to you. Upon injury, the brain takes note and typically dives into a backup plan of neurologic inhibition, neuro-protective tightness and alteration of motor patterns to protect that injured area and allow it to heal. Moderating and altering the forces and demands upon said tissues is the goal to enable healing, if we as humans, don’t get in the way first (“I have to get that run in, I am behind in my training with all these injuries !” or “Ah, its still not that bad, the pain wasn’t worse on Tuesday’s run, I will be ok.”). The bigger question for most folks is, will you listen to what your body is asking of you? Heed the warnings and messages, and your injury will come and go in a timely manner, ignore the messages and welcome to a chronic festering problem.

These protective mechanisms need to be in place, we just have to listen to them.  Failure to heed their warnings to dial things back and rest, recover and heal, the brain will make alternative changes out of necessity.

In the medpage today article in the references below, the authors discuss several important things.

“Getting a cast or splint causes the brain to rapidly shift its resources to make righties function better as lefties, researchers found.
Right-handed individuals whose dominant arm had to be immobilized after an injury showed a drop in (brain) cortical thickness in the area that controls primary motor and sensory areas for the hand, Nicolas Langer, MSc, of the University of Zurich in Switzerland, and colleagues reported.
Over the same two-week period, white and gray matter increased in the areas that controlled the uninjured left hand, suggesting “skill transfer from the right to the left hand,” the group reported in the Jan. 17 issue of Neurology.
The findings highlight the plasticity of the brain in rapidly adapting to changing demands, but also hold implications for clinical practice, they noted.”

This article highlights the rapid changes in motor programs that occur. It does not take long for the body to begin to develop not only functional adaptations but neurologic changes at the brain level within days and certainly less than 2 weeks.

So how long have you been in this pain ? If someone has to ask you this question, the process has already begun.

We tell our patients, if pain does not go away fairly quickly, that we need to get on top of the injury quickly. That is not to say you need to reach for the phone every time you have pain but you need to heighten your awareness of the injury’s status and  you need to make sure you are not driving session after session of training into a festering injury. If you do not let something heal and recover, the brain will find a way around it.  And it will imprint that new motor pattern into hard wiring, and into the hard wiring of other patterns, if you do not heed the warning signs.  This new wiring is a compensation pattern. And the longer it is there the more the neurologic pattern becomes embedded by layerings of myelin coating.  Which means that in the future, if you fatigue or injury another local tissue, this old compensation pattern is waiting in the shadows looking for an opening to rear its ugly head for old times sake.

Furthermore, on the topic of asymmetry, the above concept holds strongly true. In our clinics, we recognize asymmetry as a strong clinical finding. Despite the  Lathrop-Lambach study below, mentioning that they feel a 10% baseline asymmetry is the norm, if you do not rehab and correct both an injury and its new neurologic hardwiring changes, you have enabled and welcomed asymmetry. We feel, as many others do, that asymmetry can be a major component and predictor to injury. Logically, restoring as much symmetry as possible, both biomechanically and neurologically, is restorative and protective.

Don’t be a stoic knucklehead. Get your stuff fixed by someone who knows what they are doing. And remember, watching your gait on a treadmill or through some high tech gait analysis software and making recommendations from that information is just plain idiotic. Go see someone smart who can correlated it to examination findings. 

This article pertains to athletes and non-athletes of all walks of life. From 5 to 105 years of age, we are all susceptible to the brain’s overriding mechanisms. 

Shawn and Ivo


1. Broken arm can reorganize the brain.


Gait Posture. 2014 Jul 1. pii: S0966-6362(14)00610-9. doi: 10.1016/j.gaitpost.2014.06.010. [Epub ahead of print]
Evidence for joint moment asymmetry in  healthy populations during gait.
“We found a high amount of asymmetry between the limbs in healthy populations. More than half of our overall population exceeded 10% asymmetry in peak hip and knee flexion and adduction moments. Group medians exceeded 10% asymmetry for all variables in all populations. This may have important implications on gait evaluations, particularly clinical evaluations or research studies where asymmetry is used as an outcome. Additional research is necessary to determine acceptable levels of joint moment asymmetry during gait and to determine whether asymmetrical joint moments influence the development of symptomatic pathology or success of lower extremity rehabilitation.”

“Action Expresses Priorities”- Gandhi

“Action expresses priorities.” -Mahatma Gandhi
So much truth to this statement.  It pertains to gait analysis perfectly.  
For years now you have heard us say, “What you see is NOT what is wrong with someones gait, rather you see their COMPENSATION STRATEGY around what IS wrong.” 
The body is always strategizing to negotiate around pain, instability (functional or anatomic) or immobility.  What you see in gait are those strategies. You may not see their immobility for example, you see how they move when increasing mobility in one or multiple areas to cope with immobility in another. 
*Translation= The gait action strategy you see expresses the body’s compensation priority to make gait possible around the underlying problems that are preventing the clean, optimal and primary gait motor pattern from surfacing.
Thanks to Gray Cook for unearthing this Gandhi quote on his twitter.

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 ?”

shawn and ivo