Why we have a problem with web-based gait analysis recommendations. What is Visual Parallax and how does it affect gait analysis?

Screen Shot 2019-04-04 at 1.30.29 PM.png

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 and 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 below which we wrote 6 years 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. Does that make sense ?“

Read on . . . .

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 ?

Have you ever watched someone’s gait, only to reach for your camera to capture a gait deficit digitally, and then later re-watch the video and have a difficult time seeing the same deficit? There is a logical answer.

Vision exists with both eyes open (binocular), or with only one open eye (monocular). Our visual system uses all available depth cues to determine distances between objects, called physiological cues (actual or perceived differences), and psychological cues (experiential; or derived from past experience, or logical deduction).

Our 2 eyes see the world from slightly different locations (or different lines of sight), so the images transmitted to the visual cortex (in the occipital lobe) by the eyes are slightly different (see left picture above, compliments of Wikipedia). This difference in the perceived images is called binocular parallax. The amount or angle can be measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek parallaxis, meaning “alteration”.

Our visual system is very sensitive to these “differences”, and binocular parallax is the most important depth cue for medium viewing distances (see right picture above, compliments of www.cns.nyu.edu). The sense of depth can be achieved using binocular parallax even if all other depth cues are removed.

Nearby objects have a larger parallax than more distant objects when observed from different positions, so parallax can be used to determine distances. Usually video provides us with confirmation of we are actually seeing in 3D. Beware, visual parallax may be playing tricks with you, as there is a discrepancy when translating 3D to 2D (cameras have one lens and are therefor monocular). Yes, binocular effect is lost in video; there is little depth perception with 2D and everything on the web, at this point, is 2D. A different vantage point (ie multiple camera angles: front, back and side) often offer a different perspective which is why we always suggest 3 views, but that too, is having 3 videos which are all 2D !

So this is why when you watch someone’s gait, even when LIVE on Skype or FACETIME, you have a difficult time seeing the same deficit that you might have seen had you been there in person enabling the components of binocular and parallax to come into play. Trust us, we are astonished all the time when we see something in a client's gait, and we reach for our phone or ipad, only to have it be barely present on the video because of the 2D capture limitations.

Remember, what you see (actually or on video) IS their compensation, NOT the problem, but it can often lead you to the problem. Pelvic drift to right during stance often means weak Gluteus medius on that side. Is that the problem? Maybe. However, “Why” is the bigger question. Is it from the foot? The Knee? the hip? Or maybe central and involving the vestibular apparatus? We examine, try to make a change, and see if it sticks.

So, in the future, keep in mind some of these limitations of what you are diagnosing off of video analysis because what you are seeing is a monocular interpretation of the real thing. Some information has been lost in the process of monocular motion capture. We are sure that in time video analysis will reach the 3D realm, and solve this problem.

Binocular Parallax. 2 different views of the same thing. Kind of like us…The Gait Guys…Ivo and Shawn

Things seem to come in 3's...

Things tend to occur in threes. This includes congenital abnormalities. Take a look this gentleman who came in to see us with lower back pain.

Highlights with pictures below:

  • bilateral femoral retrotorsion

  • bilateral internal tibial torsion

  • forefoot (metatarsus) adductus

So why LBP? Our theory is the lack of internal rotation of the lower extremities forces that motion to occur somewhere; the next mobile area just north is the lumbar spine, where there is limited rotation available, usually about 5 degrees.

Dr Ivo Waerlop, one of The Gait Guys.

#tibialtorsion #femoraltorsion #femoralretrotorsion #lowbackpain #thegaitguys #gaitproblem

this is his left hip in full internal rotation. note that he does go past zero.

this is his left hip in full internal rotation. note that he does go past zero.

full internal rotation of the right hip; note he does not go past zero

full internal rotation of the right hip; note he does not go past zero

note the internal tibial torsion. a line dropped from the tibial tuberosity should go through the 2nd metatarsal or between the 2nd and 3rd.

note the internal tibial torsion. a line dropped from the tibial tuberosity should go through the 2nd metatarsal or between the 2nd and 3rd.

ditto for the keft

ditto for the keft

a line bisecting the calcaneus should pass between the 2nd and 3rd metatarsal shafts. If talar tosion was present, the rearfoot would appear more adducted

a line bisecting the calcaneus should pass between the 2nd and 3rd metatarsal shafts. If talar tosion was present, the rearfoot would appear more adducted

less adductus but still present

less adductus but still present

look at that long flexor response in compensation. What can you say about the quadratus plantae? NO bueno…

look at that long flexor response in compensation. What can you say about the quadratus plantae? NO bueno…



The smell of napalm in the morning: Your gait and trouser coughs, a clinical entity no one talks about.

Written by Dr. Shawn Allen

This is our very last gait guys blog post. Yes, all good things come to an end, even this trusted blog.
But, keeping in good faith, we will finish on a strong note ……. One of gardenia and lavender. Thanks for the last 10 years our dear gait brethren, is has been a great ride. Shawn and Ivo
The technical title of this blog post should have been, “The reactive influence of non-normopressure bowel distention and spontaneous high vapor dissipation on bipedal locomotion.” but no one but true gait nerds would have read it had we stuck with this pubmed-type title. Yes, we are talking about farts and gait here today folks, buckle up.

One biomechanical principle we will link to this entity of “off-gassing“ is that excessive or sustained ankle plantarflexion could inhibit dorsiflexion and certainly, at the very least, works against it. We have talked about this often here on the blog and how the lack of ample ankle dorsiflexion can impair many of the biomechanical events higher up into the human frame. So, how can someone’s bowel gas translate into gait problems ?

Think about this … to squeeze out a right “cheek sneak” (fart) with optimal crowd pleasing pitch and peak vibrato, some elevation and relaxation of the lower and middle gluteus maximus divisions (coccygeal and sacral) seems imperative to optimally control off-gassing . Seemingly, to do this, a significant degree of right ankle plantarflexion may be necessary to lift the right hemipelvis driving a subsequent intentional clockwise pelvic distortion assisting in the relaxation of these gluteal divisions. This consciously driven right side of the body “lift” via the right ankle plantarflexion can also be met and assisted via ipsitlateral abdominal and contralateral gluteus medius contraction to further enable the optimal right hemipelvis elevation. Go ahead, stand up and mimic the posture and note these biomechanical pieces. Recall our mantra,

“when the foot is on the ground, the glutes are in charge, when the foot is in the air, the abdominals are in charge”.

These coordinated motor patterns might be considered dual/multi tasking. This honed series of biomechanical events is one often perfected in frat houses and basement gaming rooms. But make no mistake, there is a biomechanical danger lurking here if this becomes a habitual compensation pattern, one common in large volume legume consumers (beware vegans). Habituation of this motor task, or demonstrating poor technique over time can render right quadratus lumborum shortening and weak lower abdominals rendering an anterior pelvic tilt. This tilt may lead to gluteal inhibition/weakness (because it is difficult to contract the gluteals in an anterior pelvic tilt, go ahead stand up again and try it) which over time can impair stance phase gait mechanics. However, relating to the off-gassing, this physical posturing might optimize low frequency gluteal vibrations that can optimize vibrato during gas dissipation if pressurization is in fact optimal for an “audible”. It is important to note that conscious variable control of the tonus of the muscular anal sphincter complex plays a big part in the pitch and vibrato. There is always a drawback it seems, it does truly come down to motor control it seems, doesn’t it always ?

This is not to say that avoiding “audibles” through holding “one” in doesn’t have consequences. The exotic gas (nitrogen, carbon dioxide, hydrogen, methane, oxygen) induced gut distention that could only make your collage roommate proud can inhibit the abdominal wall and thus the lower thoracic canister and disable normal breathing mechanics. This could be a serious complication to the coupled events of respiration and thoracic mobility. So, holding that big one in for your friends rather than engaging the compensatory Trendeleburg-type off-gassing posture as described above is also fraught with problems. We know that functional disconnection of the thoracic canister from the pelvic core can disrupt the normal anti-phasic mechanics of the contralateral upper and lower limbs as well as possibly impair the normal spinal cord mediated central pattern generators.

Farts…..Call them what you want, those ear pleasing, nose hair curling, trouser coughs that only a teenage boy can truly relish and recognize as a function of boyhood success. All joking aside, they truly should be your biggest concern in your gait analysis evaluation, bar none. Ask your patients about their bowels and off-gassing, it should be part of your clinical history intake. Maybe even consider taking out the discomfort of open dialogue, and put it on your intake forms. We found that a stick figure diagram in a good biomechanical squat posture with a mushroom cloud formation hanging overhead eases dialogue tension about this sensitive topic. We even give the young children crayons to they can color the cloud. What fun !

Dare us to write a part two on this topic. “Blue Angels” (unfamiliar with this clinical phenomenon? look it up). Go ahead, dare us for a part 2.

By now, if you haven’t realized that The Gait Guys just punked you (happy April Fools day) , then you likely haven’t had your cup of morning coffee. Yes, we have no clue what we were talking about on this blog post, well, ok maybe, after all we do have that y-chromosome. Yes, we are NOT ending the blog either :)

Are you now considering us juvenile ? Ok maybe we are a little, but don’t deny it, you thought about some unique and honest body biomechanics for a moment here and it is these mental gymnastics that will take your creative thinking about gait to the next level. If you are upset, so be it. There will be no apologies here in this growing PC world. "Off-gassing" is a human thing, we all do it. We have been writing serious stuff daily for 5 years here on The Gait Guys. It was time for us to write something a little lighter. We can only hope that you will think of us and the complexities of the gait cycle the next time you sneak one out while having dinner at the in-laws or before you blame the dog for any "something wicked this way comes" gaseous event. Try not to giggle when you do, but for certain, think about your body mechanics when you do, we can’t be responsible for off-gassing injuries.

Think of us, 2 juveniles at times, when the world needs us the most.

Shawn and Ivo, remaining here, for the duration.

disclaimer: we cannot be responsible for injuries that might be sustained by improper off-gassing events. Keep your work area a no smoking or vaping zone please when off-gasing. We also do not recommend attempts at performing Blue Angels, this is a potentially dangerous activity and could cause great bodily harm (seriously). :)

Running paths and the cross over gait and narrow step width.

Screen Shot 2018-11-16 at 5.39.57 PM.png

This is a walking/running path. Do the runners on this path only have one foot? No, of course not, they are running on a line. Yes, we cannot get away from this cross over gait, a terribly narrow based gait pattern.
Is it economical? Likely.
Risky ? Possibly.
Do we know that this angled attack of the foot towards the mid-line asks more from the frontal plane stabililzers in the hip and core ? Yes, research has shown this.
Do we know that the gluteus medius helps with foot targeting? Yes, research again shows this, and thus a weak gluteus medius will enable a more medial targeting. Lesson: the gluteus medius helps with foot targeting on the swing leg, and hip stability on the stance leg.
With a Cross Over gait, Do we know that we need better control of internal spin of the limb, better foot pronation durability and many other durable abilities that we might not need so much of if we were better stacking the joint? Again, yes.

We confirmed with the reader who sent the photo that this is not a bike path (at this location this path is for walking folks, the bike path is adjacent to the parking lot).
The reader (Terry B. (thank you Terry)) astutely mentioned that people are walking on a line. If they had some spacing, step width, there would be 2 trails and a tiny patch of grass between them.

But, now, this line, the line is a queue for others to "walk the line" and join the cross-over nation.
We have written gobs of articles on this cross over topic, the few benefits, the teeter-totter "risk / reward" factor, the drawbacks and injury susceptibility factor and we have spoken about it on our podcast probably 100x. IF you wish to entertain that rabbit hole of knowledge, just goto our website and type it into the "search" box. "cross over gait"

Increased unilateral foot pronation and its effects upward into the chain.

Increased unilateral foot pronation affects lower limbs and pelvic biomechanics during walking. Nothing earth shaking here, we should all know this as fact. When a foot pronates more excessively, the arch can flatten more, and this can accentuate a leg length differential between the 2 legs. But it is important to note that when pronation is more excessive, it usually carries with it more splay of the medial tripod as the talus also excessively plantarflexes, adducts and medially rotates. This action carries with it a plantar-ward drive of the navicular, medial cuneiforms and medial metatarsals (translation, flattening of the longitudinal arch). These actions force the distal tibia to follow that medially spinning and adducting talus and thus forces the hip to accommodate to these movements. And, where the hip goes, the pelvis must follow . . . . and so much adaptive compensations.
So could a person say that sometimes a temporary therapeutic orthotic might only be warranted on just one foot ? Yes, of course, one could easily reason that out.
-Shawn Allen, one of The Gait Guys

#gait, #gaitanalysis, #gaitproblems, #thegaitguys, #LLD, #leglength, #pronation, #archcollapse, #orthotics, #gaitcompensations, #hippain, #hipbiomechanics

Gait Posture. 2015 Feb;41(2):395-401. doi: 10.1016/j.gaitpost.2014.10.025. Epub 2014 Nov 3.
Increased unilateral foot pronation affects lower limbs and pelvic biomechanics during walking.
Resende RA1, Deluzio KJ2, Kirkwood RN3, Hassan EA4, Fonseca ST5.

Low Back Pain? Check for Femoral Retrotorsion on the Same Side

note the right sided leg length discrepancy

note the right sided leg length discrepancy

right tibia is anatomically shorter

right tibia is anatomically shorter

more internal rotation available on the left side at the hip. Note the internal tibial torsion as well

more internal rotation available on the left side at the hip. Note the internal tibial torsion as well

very little internal rotation available at the right hip

very little internal rotation available at the right hip

This right handed concrete worker presented to our office with right-sided lower back pain. He was lifting a bag of concrete moving from left to right which she estimates weighing between 60 and 80 pounds. He did this repetitively throughout the day and subsequently developed right sided lower back pain. The pain is in the suprailiac region and is described as dull, achey. Is exacerbated by right rotation and right lateral bending.

His exam found him to have a right sided anatomical leg length discrepancy, tibial left (see above) and femoral retro torsion on the right with no internal rotation of the hip past 0 degrees (see picture of full internal rotation of the right hip and cmpare it with the left); left side had approximately 10 degrees internal rotation. He also has bilateral internal tibial torsion, R > L. Palpation findings revealed tightness in the lumbar multifidus and quadratus lumborum with a loss of lateral bending to the right at L2 through L4 and a loss of flexion about the right sacroiliac joint. Lower extremity reflexes were 2+ with bilateral symmetry; sensation to vibration was intact at the distal phalanges; motor strength was strong and graded as 5/5.

Think about the implications of his right-sided leg length discrepancy first. This places his foot and a relative supinated posture compared to the left. Remember that supination is plantar flexion, inversion and adduction.

His femoral retro torsion on the right limits his internal rotation at the hip. When his foot planted with a diminished progression angle secondary to the internal tibial torsion, and he has to rotate from left to right, very little, if any motion, can occur at the right hip and therefore must occur in the lumbar spine. Remember the lumbar spine has very limited range of motion begin with with most of that occurring at the L5-S1 junction, depending upon its anatomy. Now superimpose a long lever load and rotary force. Back pain!

We instructed him on proper lifting technique and also talked about keeping the shoulders and hips in the same plane when lifting or load. If he does need to lift a load and spin unilateral on his right lower extremity, we asked him to externally rotate the right lower extremity. He was treated with manipulation and neuromuscular acupuncture.

If you have somebody with unilateral lower back pain, think about the implications if they have any femoral torsion or version present

Dr. Ivo Waerlop, one of The Gait Guys.

#lowbackpain #LBP #femoralretrotorsion #femoral #torsion #gait #gaitanalysis #thegaituys

Motion control Shoes + Internal Tibial Torsion = Knee Pain

Thinking about putting a motion control shoe under that foot to control pronation? You had better make sure you make friends with the knee, as it will often (depending on the compensation) be placed OUTSIDE the SAGGITAL PLANE. Like Dr Allen has said many times before , the knee is basically a hinge joint placed between 2 ball and socket joints, and it is usually the one to start grumbling...

Learn more as Dr Ivo Waerlop of The Gait Guys explains in this brief video

#gait #Gaitanalysis #gaitguys #thegaitguys #kneepain #motioncontrolshoes #internaltibialtorsion


Low back tightness in runners. Spinal muscle fatigue.

Do you as a runner, or a helper of runners, ever experience low back tightness on a run, particularly a long run ? These muscles can fatigue just like any other muscle; we just generally do not think of them in this manner. Be sure to endurance/fatigue test your runner's lumbar erector muscles. Sure, we need a strong durable core, but in an endeavor like running, where there are constant acceleration/deceleration as well as impact loading forces over long distances, we need these muscles to be just as durable as any other.
And, do not forget that we have to control the constant anterior and posterior pelvis oscillations in the sagittal plane (APT and PPT) that correspond to the acceleration and deceleration phases of gait.

"Previous EMG studies of running have shown the lumbar extensor muscles to be active at foot contact and during early stance (Thorstensson, Carlson, Zomlefer, & Nilsson, 1982). This early activation of the back extensors will act to limit forward flexion of the trunk as energy is absorbed in the lower limbs and the CoM decelerates. During this deceleration phase, the thorax moves into forward flexion and there is a small corresponding posterior tilt of the pelvis as gluteus maximus acts to extend the hip."
S.J. Preece et al. / Human Movement Science 45 (2016) 110–118

When you run Do you kick or scrape the inside of your ankle with the other foot ?

Do you kick or scrape the inside of your ankle with the other foot ?

Runner's pathologies creep in as the miles go up, fatigue can be a variable in biomechanical breakdown. Some of you who have been with us for years have seen this picture. This young runner had these scuff marks on the inside of the right lower leg and ankle after a cross country meet. So what is going on here and what does it tell you ?

Screen Shot 2019-01-06 at 10.57.30 AM.png

Some runners notice that they repeatedly will scuff in the inside ankle or inner calf with the opposite shoe when running. This can happen on both sides but it is more often present unilaterally than bilaterally.

This problem, typically, but not always represents one of two things:

1- cross over gait (if you are new to our blog in the SEARCH box type in “cross over” and “cross over gait” and be sure to see our 3 part video on the cross over on our youtube channel found here).

2- negative foot progression angle which may or may not be combined with a degree of internal tibial torsion. Said easier, the runner is “in-toed” or “pigeon toed” but if you have been here with us awhile on The Gait Guys we expect a diagnosis of a higher order so use the former terms, please.

Lets discuss both.

1- Cross over. When the runner is standing on the right leg, right stance phase of gait, the frontal plane is not properly engaged and the pelvis can drift further over the right foot. This drift to the right will drop the pelvis on the left side. This will alter the pendulum movement of the left leg. Since the global pelvis is moving to the right the left swing leg pendulum moves to the right as well and as it swings past the stance leg it strikes a glancing blow to the inside of the right ankle or calf. This is simple biomechanics and physics. To fix this problem, which is clearly inefficient, one has to determine what is causing the right pelvis drift (there are many causes, the most often thought of cause is a weak gluteus medius on the right but if you have been here with us awhile you will know there are other causes) and then fix the drift. Do not assume it is the gluteus medius all the time, for if it is not, and you employ more glute medius exercises you could be ignoring the source and building a deeper compensation pattern. Fix the problem, not what you see.

2- Negative foot progression angle and/or internal tibial torsion. In order to fix this you have to know first if you are dealing with a fixed/rigid anatomic tibial or femoral torsion issue which cannot be fixed or if you are dealing with a flexible progression angle issue. Often, “in-toeing” is accompanied with internal tibial torsion, this is because the knee has to progress forward to keep its tracking mechanics clean, if you correct someone’s foot progression back to neutral and they have internal tibial torsion then you have dragged the patellar tracking outside the normal sagittal progression angle, knee pain will ensue. In fact, the foot progression on the ankle is normal, but the tibia or femur are merely torsioned in a manner that drags the foot inwards with the long bone orientation, again, this is driven by a higher order/demand, to normally track the patella sagittally (forward). However, if this is a pre-puberty individual you have time because the long bone derotation process is still occuring. Give homework to encourage a good foot tripod and work to strengthen the external hip rotators and encourage sagittal knee tracking mechanics. This is a delicate balancing act, but it can be done, but it is a monster of a project for a blog post because each case is different, variable and always changing depending on the client progress. Remember, you can only encourage more appropriate mechanics and hope that the body will embrace some of the change and encourage some of the de-rotation process to occur from the long bone growth plates.

The “inside scuff”, to identify its solution you have to know the cause. After all, if it was as easy a fix as “stop doing that” no one would be doing it and we would be out of a job.

Shawn and Ivo …… The Gait Guys

#gait, #gaitanalysis, #gaitproblems, #thegaitguys, #gaitcompensations, #hippain, #hipbiomechanics, #crossovergait, #narrowstepwidth, #calfscuff

Loading protocols for achilles tendinopathy.

We all know now that the smartest way out of a chronic tendinopathy is painfree, progressive loading. We, as many others have found, that isometrics serve the initial process well because there is no movement through a painful arc, the isometrics can help reduce the neurologic pain loop, and we can more easily find positions where there is no pain in the tendon. This allows us to load the affected tendon, without adding insult to the tendon portion that is injured. It them prepares us for the weeks to months of eccentric and concentric loading that is often necessary to restore function. Keep in mind that some of the literature indicates that some tendons never fully heal, but we replace things with a better functioning of the remaining competent tendon.

This study found that there was an improvement in pain and function as early as 2 weeks. You might find this interesting because on imaging tendon structure does not change within 2 weeks and muscular hypertrophy is not seen for at least 4 weeks following inception of a loading protocol (Murphy). Thus, we all need to continue our education and understanding of central pain mechanisms. Meaning, that these initial early changes, are in part, and maybe a huge part, are neurologic.

Sports Med. 2018 May 15. doi: 10.1007/s40279-018-0932-2. [Epub ahead of print]
Rate of Improvement of Pain and Function in Mid-Portion Achilles Tendinopathy with Loading Protocols: A Systematic Review and Longitudinal Meta-Analysis.
Murphy M1,2,3, Travers M4,5, Gibson W4, Chivers P6,7, Debenham J4, Docking S8, Rio E8,9.

When the Windlass is lost.

When the Windlass is lost.
Here, this case again (hallux amputation), when the Windlass is lost or at the very least, impaired, what holds up the arch?
Without the winding of the plantar fascia through hallux dorsiflexion (toe extension) and without the FHL (flexor hallucis longus) we lose major engineering advantages to lift/support the arch and control pronation variables.
So what is left ?
Tibialis posterior, tibialis anterior, peroneus longus, mostly, are what is left. So when these guys are suffering (ie, tendinopathy etc) it could be due to the other previously mentioned engineering marvels being impaired.

It is a team effort to keep the foot healthy and functioning without expressible pathology.

*note the heavy flexion attempts of the 2nd toe, the next soldier in line, no surprise there.
Now you should realize why you see this 2nd toe over-flexion attempts when even an existing, yet incompetent, hallux is present.

This slide is part of a new presentation, one we will be doing a WEBEX on that you can all join in on, and it will be a new presentation for our onlineCE Wednesday night seminars.

Now, go read this dudes blog, inspirational journey through big toe cancer. Thanks for sharing your story Kevin, and your case photos. (PS: presentation is almost done, so i will be in touch soon so we can go over it and collaborate).

#gait, #gaitanalysis, #gaitproblems, #thegaitguys, #gaitcompensations, #halluxamputation, #windlassmechanism, #halluxdorsiflexion, #pronation, #FHB, #FHL, #hammertoes, #theagecoach

Podcast 145: Tendons, Heel Drop and their impacts on the posterior chain,

Heel lifts, Sole lifts and their impact on the EMG of the posterior chain.

Keywords: gait, gait analysis, gait problems, running, ankle, tendinopathy, heel lifts, sole lifts, EMG, paraspinal activity, gluteal inhibition, posterior chain, anterior pelvic tilt, tight quads, diagnostic ultrasound

Links to find the podcast:
Look for us on iTunes, Google Play, Podbean, PlayerFM and more.
Just Google "the gait guys podcast".

Our Websites:
Find Exclusive content at: https://www.patreon.com/thegaitguys

Our website is all you need to remember. Everything you want, need and wish for is right there on the site.
Interested in our stuff ? Want to buy some of our lectures or our National Shoe Fit program? Click here (thegaitguys.com or thegaitguys.tumblr.com) and you will come to our websites. In the tabs, you will find tabs for STORE, SEMINARS, BOOK etc. We also lecture every 3rd Wednesday of the month on onlineCE.com. We have an extensive catalogued library of our courses there, you can take them any time for a nominal fee (~$20).

Our podcast is on iTunes and just about every other podcast harbor site, just google "the gait guys podcast", you will find us.

Where to find us, the podcast Links:

iTunes page:

Google Play:

Direct download URL: http://traffic.libsyn.com/thegaitguys/pod_149raw_-_31619.mp3

Permalink URL: http://thegaitguys.libsyn.com/podcast-tendons-heel-drop-and-their-impacts-on-the-posterior-chain

Libsyn Directory URL: http://directory.libsyn.com/episode/index/id/9027890

Show notes:

Current trends in tendinopathy management
Tanusha B.Cardosoa, TaniaPizzarib, RitaKinsellab, DanielleHopec, Jill L.Cook


Insightful paper on how tendon adapts to loading and unloading. Discusses a lack of evidence supporting eccentric training as the treatment of choice for injury and notes that tendon response to loading is not normalized until ~6-12 months after injury
The impact of loading, unloading, ageing and injury on the human tendon
S. Peter Magnusson, Michael Kjaer

Effects of heel lifts on lower limb biomechanics and muscle function: A systematic review
Chantel L.Rabusinac, Hylton B.MenzacJodie A.McClellandbcJade M.TanacGlen A.WhittakeracAngela M.EvansaShannon E.Munteanuac

The influence of high and low heeled shoes on EMG timing characteristics of the lumbar and hip extensor complex during trunk forward flexion and return task
AnnaMikaa, Brian C.ClarkbcŁukaszOleksy

The effect of heel lifts on trunk muscle activation during gait: A study of young healthy females
Christian J.Bartonac, Julia A.CoyleaPaulTinley

A Systematic Review and Meta-Analysis of Crossover Studies Comparing Physiological, Perceptual and Performance Measures Between Treadmill and Overground Running

Plantarflexor strength and endurance deficits associated with mid-portion Achilles tendinopathy: The role of soleus - ScienceDirect

1st MTP Pain? The Biomechanics of the Big Toe...

Remember the rockers? We have done a series on this in the past. Remember there are three: heel, ankle and forefoot. We are going to concentrate on the forefoot today.

As a reminder, forefoot rocker occurs at the 1st metatarsal phalangeal joint (big toe knuckle) as the tibia progresses over the forefoot during forward movement. You NEED 50 degrees to do this competently; you SHOULD have 65 degrees. When you don’t, you have a condition called hallux limitus. This could be from a number of reasons, from overpronation in the mid foot, to a bunion, to faulty firing patterns of the muscles which help to descend the 1st ray (the extensor hallucinations brevis, the peroneus longs and the short flexors off the toes). Pretty much, ANYTHING that causes a dorsal and posterior shift of the 1st MTP axis will cause limited forefoot rocker.

So, the question is, “Do you know where 1st 1st MTP pain may be coming from? How familiar are you with the mechanics of that joint?”

Take a few minutes to review it in this video with Dr Ivo Waerlop of The Gait Guys.

#gait, #gaitanalysis, #1stmtp, #forefootrocker, #thegaitguys,

NO hip internal rotation? Forget the glutes, have you looked at the femur?

Screen Shot 2019-02-14 at 3.13.23 PM.png

Some developmental versions involve the femur. The degree of version is the angle between an imaginary line drawn through the condyles of the femur and an imaginary line drawn through the head and neck of the femur. This is often referred to as the femoral neck angle or FNA.

Beginning about the 3rd month of embryological development (Lanz and Mayet 1953) and reaches about 40 degrees (with an average of 30-60 degrees) at birth. It then decreases 25-30 degrees by adulthood to 8-20 degrees with males being at the lower and females at the upper end of the range.

The FNA angle, therefore, diminishes about 1.5 degrees a year until about 15 years of age. Femoral neck anteversion angle is typically symmetrical from the left side to the right side.

What causes torsion in the first place? By the sixth month in utero, the lumbar spine and hips of the fetus are fully flexed, so perhaps it is positional. Other sources say it coincides with the degree of osteogenesis. There is a growing consensus that muscular forces are responsible, particularly the iliopsoas  or possibly the medial and lateral hip rotators.

Additional changes can occur after birth, particularly with sitting postures. “W” sitting or “cross legged” sitting have been associated with altering the available range of motion and thus the FNA, with the range increased in the direction the hip was held in; W sitting causing increased internal rotation and antetorsion and cross legged causing external rotation and retro torsion.

There are at least 3 reasons we need to understand torsions and versions, They can alter the progression angle of gait, they usually affect the available ranges of motion of the limb and they can alter the coronal plane orientation of the limb.

1. fermoral torsions often alter the progression angle of gait.  In femoral antetorsion torsion, the knees often face inward, resulting in an intoed gait and a decreased progression angle of the foot. This can be differentiated from internal tibial torsion (ITT) by looking at the tibia and studying the position of the tibial tuberosity with respect to the foot, particularly the 2nd metatarsal. In ITT, the foot points inward while the tibial tuberosity points straight ahead. In an individual with no torsion, the tibial tuberosity lines up with the 2nd metatarsal. If the tibial tuerosity and 2nd met are lined up,  and the knees still point inward, the individual probably has femoral ante torsion. Remember that a decreased progression angle is often associated with a decreased step width whereas an increased angle is often associated with an increased step width. See the person with external tibial torsion in the above picture?

2. Femoral torsions affect available ranges of motion of the limb. We remember that the thigh leg needs to internally rotate the requisite 4-6 degrees from initial contact to midstance (most folks have 40 degrees) If it is already fully internally rotated (as it may be with femoral retro torsion), that range of motion must be created or compensated for elsewhere. This, much like internal tibial torsion, can result in external rotation of the affected lower limb to create the range of motion needed.

Femoral retro torsion results in less internal rotation of the limb, and increased external rotation.

Femoral ante torsion results in less external rotation of the limb, and increased internal rotation.

3. femoral torsions usually do not effect the coronal plane orientation of the lower limb, since the “spin” is in the transverse or horizontal plane.

The take home message here about femoral torsions is that no matter what the cause:

  •  FNA values that exist one to two standard deviations outside the range are considered “torsions”

  • Decreased values (ie, less than 8 degrees) are called “retro torsion” and increased values (greater than 20 degrees) are called “ante torsion”

  • Retro torsion causes a limitation of available internal rotation of the hip and an increase in external rotation

  • Ante torsion causes an increase in available internal rotation  of the hip and decrease in external rotation

  • Femoral ante torsion will be perpetuated by “W” sitting (sitting on knees with the feet outside the thighs, promoting internal rotation of the femur)

  • Femoral antetorsion will be perpetuated by sitting cross legged, which forces the thigh into external rotation.

Dr Ivo Waerlop, one of The Gait Guys

#gait, gait analysis, #thegaitguys, #femoraltorsion, #antetorsion, #retrotorsion

Crawling patterns and the Bird Dog look alike, but they are clearly not. Do you understand this ?

Screen Shot 2019-02-24 at 9.48.00 AM.png

Crawling and Bird Dog, a subtle but important difference.

Can you see it ?
When we crawl, as in the photo, we use the following pattern:
- the right shoulder is in extension (but it is fixed on the ground, it is the body that is moving forward/extending over this fixated point, it is approximating the flexing right hip as the knee moves up towards the hand)
- the left hip is in extension, pairing appropriately with the right shoulder extension.
- similarly, the left shoulder is in flexion (it is over head in this photo, just like in the other photo of the runner similarly doing the same patterning but standing up, meanwhile the right hip is in flexion.
* take the photo of the runner in the green shirt, and put him in a quadruped crawling pattern as you will see that it is the same pattern as the one of me in the crawling posture.
* This is not bird dog, as seen in the photo, do not confuse them.

Screen Shot 2019-02-24 at 9.44.31 AM.png

The Bird Dog exercise is not neurologically correct for the reason of training the proper crossed patterning from a neuro perspective. Note that in the 2nd photo, the bird dog, the same left arm is in flexion, but his left leg is in EXTENSION ! If you want to use the bird dog to teach core engagement, that is one thing, but do not think you are coordinating normal gait patterns or the proper crossed response. This is why we do not use the Bird Dog with our patients, it goes against training fundamental gait patterns.

Screen Shot 2019-02-24 at 9.44.19 AM.png

This first photo of me in the black shirt is normal, natural, neurologically correct, cross crawling. Don't believe us ? Get on the floor and crawl like an infant, it is no where near the bird dog exercise, in crawling the coupled crossed extension and flexion responses are NOT conflicting. So, just because the Bird Dog "sort of looks like crawling" do not get it confused with crawling, because it is not. It is a mere balance exercise, some use it for the core stability, but it is one based on UN-fundamental neurologic patterning we use every day.......something called gait, and running, things we do in our sports. So understand what message you are sending to the CNS.
We are not saying the Bird Dog does not have value, not at all, but if you are not thinking about what it actually is doing, you might be driving patterns you do not want.

An often overlooked culprit...In hip and hamstring insertional pain

The "Deep 6". In order from proximal to distal; the piriformis, obturator internus, gemelli superior, obturator externus, gemelli inferior and quadratus femoris. They are primarily external rotators but have a small footprint and act primarily as stabilizers. Here is what we think and what we have to say about them...

Dr Ivo Waerlop, one of The Gait Guys

#deepsix, #gait, #thegaitguys, #hipexternalrotators, #hipstabilizers, #running

The Bird Dog rehab exercise is neurologically incorrect. Know what you are asking your client to do, and why..

Screen Shot 2019-02-24 at 9.44.19 AM.png

Runners, athletes . . . Even in your drills, do it correctly !
Is this Bird Dog standing up? No, look more closely.

Photo #1: pull that right swing leg outwards with your abductors/external rotators. Do not let the knee drift inwards, it will lead to that foot targeting the midline. Plus, because of the neurologic links, it will encourage the left arm to cross the mid line (see yesterdays FB blog post). The upper limb movement can shape lower limb movement. An aggressively narrow cross over gait is undesirable in many aspects, it might be more economical, but it has a wallet full of potential liabilities.
IF you train your machine in a lazy manner, it is not unlikely it will perform as such. Get that knee under the shoulder, not under your head.

Aside from that, this is a good drill. It is neurologically correct. Note that:
- the right arm is in extension and the left hip is in extension
- the left arm is in flexion and the left knee is in flexion.
This is neurologically correct cross crawling.

Screen Shot 2019-02-24 at 9.44.31 AM.png

* VERY important point:
the Bird Dog exercise is not neurologically correct for the reason of training the proper crossed patterning from a neuro perspective. Note that in the 2nd photo, the bird dog, the same left arm is in flexion, but his left leg is in EXTENSION ! If you want to use the bird dog to teach core engagement, that is one thing, but do not think you are coordinating normal gait patterns or the proper crossed response. This is why we do not use the Bird Dog with our patients, it goes against training fundamental gait patterns.
When we crawl, we use the following pattern:
- the right arm is in extension and the left hip is in extension
- the left arm is in flexion and the left knee is in flexion.

This is neurologically correct cross crawling. Don't believe us ? Get on the floor and crawl like an infant, it is no where near the bird dog exercise, in crawling the coupled crossed extension and flexion responses are NOT conflicting. So, just because the Bird Dog "sort of looks like crawling" do not get it confused with crawling, because it is not. It is a mere balance exercise, some use it for the core stability, but it is one based on UN-fundamental neurologic patterning we use every day.......something called gait, and running, things we do in our sports. So understand what message you are sending to the CNS.
We are not saying the Bird Dog does not have value, not at all, but if you are not thinking about what it actually is doing, you might be driving patterns you do not want.

Arm swing, cross over, head over foot?

Screen Shot 2018-11-16 at 5.16.36 PM.png

Here is a Birdseye view of someone in full stride gait. The left leg and the right arm are into flexion and external rotation.
The right leg and left arm are into extension and internal rotation.
We discussed this in depth on our lecture on wednesday night.
These counter movements drive,and are driven by, the anti-phasic properties of normal gait.
Now, lets posture some thoughts with the head-over-foot mentality (which we do not subscribe to(listen to podcasts 135-136)). . . . You can see the clear relationships here of coupled motions of the limbs. Now imagine that you forced a cross over arm swing, pumping arm Swing across your body. This is shoulder/arm adduction. So what do you think is likely going to happen in the lower limb? Yes step width narrowing, i.e. crossover gate/Leg adduction. By forcing the arms to cross the midline you are strongly encouraging the legs to do the same thing. As we have discussed many times previously, the arms can shape the movement of the lower limbs even though the lower limbs run the primary patterns of which the arms are driven from. So if you want a crossover gait , which we have for years documented research showing biomechanical challenges, and something we see many injuries driven from, go ahead and coach and train your arm swing across the body.

When runner do you want to be? 2 photos

Screen Shot 2019-02-24 at 9.29.56 AM.png
Screen Shot 2019-02-24 at 9.29.44 AM.png

Who do you want to be ? The guy loading his head over his foot
(narrow step width), or the gal loading the head and COM inside the foot (less narrow step width) ?

It is not hard to suspect who is gonna be faster and more powerful from these photos. This however does not mean on is more durable, more or less injured, more or less efficient but logical debates and thought experiments can be made here.

The lady is stacking the knee over the foot, the hip over the knee and stabilizing the hip and pelvis sufficiently and durably to keep the pelvis level for the next powerful loading step, and the other is flexion collapsing into the stance phase knee, insufficiently loading the hip and thus dropping the opposite side pelvis. He is not stacking the joints, there is a pending cross over (look at the swing leg knee approaching midline with barely any knee spacing, thus guaranteeing a cross over step or at the very least a very narrow step width.)
Sure, some one is going to say one is a distance runner and the other is a sprinter. Yes, and our point is that the sprinter is not head-over-foot, the one with all the highly suspect flaws is head over foot ! Wider step width means more glutes. Go ahead, walk around right now with a very narrow step width and see how little efficient glute contraction you get, then walk with a notably wider step width, and you will see wider means more glutes. Keep your COM moving forward, not oscillating back and forth sideways over each stance foot, that is a power leak.

The distance runner appears to be demonstrating less optimal in technique, appears is the key word here. Say what you want, but a decent argument might be made as to one of these runners being weak and very likely at greater risk for injury, the other is suspect to be strong and durable, and likely at less risk for injury.
If you ask us, but what do we know . . . . it is all a thought experiment, but based on some pretty decent ideas.
So, again, was ask . . . . which one do you want to be ?

The hip flexors do not cause initial hip flexion.

The hip flexors are not responsible for pulling/flexing the swing leg forward in gait or running. The psoas is a mere swing phase perpetuator, not an initiator.
For about 2 decades we have been saying in our lectures, posts and podcasts that it is the reduction of the obliquity of the pelvis during gait from various other tissues and biomechanical events that causes leg swing, meaning the trail leg is brought forward in swing largely by the abdominal muscle linkage to the pelvis (and other loaded tissues) that is responsible for forward swing of the leg. It is not the hip flexor group that does this hip flexion action. Thus it could be considered foolish to train the hip flexors to be the primary swing drivers. Here is another supporting piece of research.

"These experiments also showed that the trailing leg is brought forward during the swing phase without activity in the flexor muscles about the hip joint. This was verified by the absence of EMG activity in the iliacus muscle measured by intramuscular wire electrodes. Instead the strong ligaments restricting hip joint extension are stretched during the first half of the swing phase thereby storing elastic energy, which is released during the last half of the stance phase and accelerating the leg into the swing phase. This is considered an important energy conserving feature of human walking. "

Dan Med J. 2014 Apr;61(4):B4823.
Contributions to the understanding of gait control.
Simonsen EB1.