Pod 144: Grounded running, Glute fatigue & Stress Fractures

Topics: Grounded running, Glute fatigue, Stress Fractures, Duty Factor, Ankle stiffness & Gait and Concussions

Keywords: gait, gait analysis, gait problems, running, ankle, band, concussions, fatigue, fracture, gait, glutes, grounded, gait guys, glute medius, problems, stiffness, stress, syndrome, time under tension

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

Our Websites:
www.thegaitguys.com
Find Exclusive content at: https://www.patreon.com/thegaitguys
doctorallen.co
summitchiroandrehab.com
shawnallen.net

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:
https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138?mt=2

Google Play:
https://play.google.com/music/m/Icdfyphojzy3drj2tsxaxuadiue?t=The_Gait_Guys_Podcast

Direct download URL: http://traffic.libsyn.com/thegaitguys/pod_147_raw_-_21619_11.08_AM.mp3

Permalink URL: http://thegaitguys.libsyn.com/pod-144-grounded-running-glute-fatigue-stress-fractures

Libsyn Directory URL: http://directory.libsyn.com/episode/index/id/8666903

Show notes:

Hip muscle response to a fatiguing run in females with iliotibial band syndrome.
Brown AM1, Zifchock RA2, Lenhoff M3, Song J4, Hillstrom HJ3.
Hum Mov Sci. 2019 Feb 8;64:181-190. doi: 10.1016/j.humov.2019.02.002. [Epub ahead of print]

Balance and Gait Alternations Observed More than 2 Weeks after Concussion: A Systematic Review and Meta-analysis.
Wood TA1, Hsieh KL1, An R1, Ballard RA2, Sonoff JJ1.
Am J Phys Med Rehabil. 2019 Feb 5. doi: 10.1097/PHM.0000000000001152. [Epub ahead of print]

Does Running Faster Put You at Greater Risk of a Stress Fracture?
New research finds that speed might not cause as much strain on the shins as we thought
By Hailey Middlebrook
Feb 12, 2019
https://www.runnersworld.com/health-injuries/a26221848/stress-fracture-speed-study/

Fast Running Does Not Contribute More to Cumulative Load than Slow Running\
Hunter, Jessica G.1; Garcia, Gina L.1; Shim, Jae Kun1,2,3; Miller, Ross H.1,2
Medicine & Science in Sports & Exercise: January 25, 2019

https://journals.lww.com/acsm-msse/Pages/articleviewer.aspx?year=9000&issue=00000&article=96699&type=Abstract


Grounded running Reduces Musculoskeletal Loading.
https://www.ncbi.nlm.nih.gov/pubmed/30480615
Med Sci Sports Exerc. 2018 Nov 21
Bonnaerens S1, Fiers P1, Galle S1, Aerts P1,2, Frederick EC3, Kaneko Y4, Derave W1, De Clercq D1.

Duty factor:
duty-factor. The duration of a gait cycle where each foot is on the ground
https://www.researchgate.net/figure/Illustration-of-the-duty-factor-The-duration-of-a-gait-cycle-where-each-foot-is-on-the_fig2_221908232

Ankle intrinsic stiffness changes with postural sway
PouyaAmiri, Robert E.Kearney
https://www.sciencedirect.com/science/article/pii/S0021929019300387


COM (center of mass) between the feet (inside step width?)

Center of Mass between the feet . . .

The coordinated movement of the spine and pelvis during running. Preece SJ1, Mason D2, Bramah C3.
Hum Mov Sci. 2016 Feb;45:110-8. doi: 10.1016/j.humov.2015.11.014. Epub 2015 Nov 24.

"There appeared to be an anti-phase relationship in the frontal plane between thorax and pelvic motion (Fig. 1b and h)
during stance. Specifically the thorax was laterally flexed towards the stance limb during early stance AND THEN MOVED
TOWARDS A NEUTRAL position during the latter half of stance, as the pelvis became elevated on the contralateral side. The coordination analysis classified the frontal plane pelvis–thorax motion as either anti-phase or pelvis-only during stance (Fig. 4b). This latter classification resulted from the increased motion of the pelvis compared to the thorax which resulted in a more
vertically aligned coupling vector (Seay et al., 2011b) and therefore a coupling angle which was classified as pelvis-only
motion."

This study supports our well founded beliefs that the COM moves within the confines of the step width, it moves TOWARDS, but not over the foot in the early stance phase, and then moves back towards a neutral position during the latter half of stance. One must fully understand the implications of the antiphasic nature in the planes of motion of the body during running (and walking) to understand what the COM is truly doing, what it is not doing, and what it should not be doing.

This study concluded,
"This is the first study to provide an underlying biomechanical rationale for the coordination pattern between the pelvis
and thorax during running in all three body planes. The data showed an anti-phase relationship between these two segments in the sagittal and frontal planes and we suggest that this in a consequence of the requirement to minimise accelerations of the CoM in the AP and ML directions."

The coordinated movement of the spine and pelvis during running. Preece SJ1, Mason D2, Bramah C3.
Hum Mov Sci. 2016 Feb;45:110-8. doi: 10.1016/j.humov.2015.11.014. Epub 2015 Nov 24.

Step width: Head over foot ?

Step width, "head over foot"?

There has been some decent debate on "head over foot" running biomechanics. We postulate from our years of reading research and studying people's gait (coupled with physical examination, a neuromuscular assessment, not just a visual assumption) that the head should remain within the limits of the step width. This theory falls apart if someone is a crossover gait runner or walker (search our blog for this "cross over gait" idea). IF one is a narrow step width (cross over gait, not a literal cross over of course) then the head must basically be over the foot on each step. But this is a gait with severe limitations and lots of risks and biomechanical problems as we have written about many times, though one can say is has some economical aspects which we have proposed many times.
But, if the head is outside the step width, one is leaning and this resembles a pathologic Trendelenburg gait. Can we definitively then say that when the head is outside the foot contact (beyond the limits of a person's step width) that it is problematic? No, but it is likely pathologic and clearly uneconomical.

So the fence seems to be the head over the foot.
If you are outside that fence even a little, you may be (we strongly believe) on the wrong side of the fence. Look at a CP gait (photo below) for example, point made. So, would you rather be on the other side of the fence? We would, we want to be inside the step width and we are fine going right up against the fence (the head foot) but not over top of it. One cannot just say that the head over the foot is better. What about hip and pelvis stability ? If the hips-pelvis are drifting into the frontal plane, this will put the head over the foot as a default. So does this validate the head over foot theory as good in this client ? No, we see this as a problematic gait all the time, lots of hip and spinal stability issues in these clients. One cannot stand and preach on head over foot alone. We just made the case that in a frontal plane drift pelvis client, this is a compensatory default, but it doesn't make it a good thing, far from it.

For now, we will stay put that, with all other faulty mechanics not present, a more sound head position is to be found between the limits of the step width. Yes, right up to the fence of "head over the foot", but not over top as a sound pattern to play with. Why risk falling over the fence on some steps, Try this, stand on one foot, put your head over the foot. In this position, you had to drift the pelvis laterally into the frontal plane. Now try to effectively engage your glute. Enough said, for now. So why would we promote this as an effective running form? More to come we are certain, but we are open to debate, and to being schooled wrong. If you wish, go into our blog (link below) and read up on the effects of step width on gait, and all of the risks/problems that a narrow step width promotes (ie. head over foot).

https://www.google.com/search?q=the+gait+guys+step+width&ie=utf-8&oe=utf-8&client=firefox-b-1-ab

Dominance of the lumbosacral girdle over the cervicothoracic is probably preserved in humans

. . . dominance of the lumbosacral girdle over the cervicothoracic is probably preserved in humans
This suggests that arm swing is, to a notable degree, subservient to leg swing.

Research thus far has strongly suggested two pieces to arm swing, a passive and an active swing component. Without muscle activity, passive swing amplitude and relative phase decrease significantly. As phase decreases, it is referred to as in-phase swing pattern of the arms. The Goudriaan et al paper referenced below concluded that "muscle activity is needed to increase arm swing amplitude and modify relative phase during human walking to obtain an out-phase movement relative to the legs."
But it is more complicated that this . . . .

Research continues to suggest that interlimb coordination is achieved at the brainstem and cortical level, which this study suggests as to why we can dual task and walk with something in our hands, carry objects and even walk and run with said objects and changes in our gait . . . . because, the program is running off a top down neurologic mediated process with predictable, economically CPGs(central pattern generator) in place.
"The coordination of arm and leg movements takes the form of an in-phase relationship between diagonal limbs [64]. The dominance of the lumbosacral girdle over the cervicothoracic is probably preserved in humans as well. For example, Sakamoto et al. [65] showed that during combined arm and leg cycling, the cadence of the arms was significantly altered when leg cycling cadence was changed. The opposite, however, was not true, i.e. the arms did not affect the leg cadence."-Preece et al.

Human Movement Science 45 (2016) 110–118
The coordinated movement of the spine and pelvis during
running
Stephen J. Preece, Duncan Mason, Christopher Bramah
School of Health Sciences, University of Salford, Salford, Manchester M6 6PU, United Kingdom

Gait Posture. 2014 Jun;40(2):321-6. doi: 10.1016/j.gaitpost.2014.04.204. Epub 2014 May 6.
Arm swing in human walking: what is their drive? Goudriaan M1, Jonkers I2, van Dieen JH3, Bruijn SM4.

Pod 136: Part 2: Head over Foot? Where should we put our COM (center of mass)?


This podcast (135) and its soon to launch follow up podcast (136), as the intro explains, comes at the tail end of a series of thought debates between Shawn and Ivo with some folks who have a different view point.  While the debate is unsettled because there is not sufficient research to support one side, we feel the research leans towards our side of things.  However, as the debates went on, it became clear to us that both parties were approaching the debate from a different metric to gauge each party's beliefs.  We outline this in the introduction and then more forward into our dialogue.  We hope you find this a productive thought experiment.

Key words: cross over gait, head over foot, HOF, gait, gait analysis, COM, COP, center of mass, center of pressure, step width, sprinting, symmetry, running injuries

Links to find the podcast:

iTunes page: https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138?mt=2

Direct Download: http://traffic.libsyn.com/thegaitguys/pod_136final.mp3

Permalink URL: http://thegaitguys.libsyn.com/pod-136-part-2-head-over-foot-where-should-we-put-our-com-center-of-mass

Libsyn URL:http://directory.libsyn.com/episode/index/id/6586622


Our Websites:
www.thegaitguys.com

summitchiroandrehab.com doctorallen.co shawnallen.net

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.

You won't read this. So send it to a colleague who will.

Screen Shot 2018-03-08 at 9.28.02 AM.png

Beating a point to near-death. Consider this our Thursday Rant.

Yes, we won't let this go, and, you should not either.

We highlight the word ADAPTIVE below, because it is the key to all of this.

"The observed postural responses could be viewed as an ADAPTIVE process to cope with an unilateral alteration in the hip neuromuscular function induced by the fatiguing exercise for controlling bipedal stance. The increase in CoP displacements observed under the non-fatigued leg in the fatigue condition could reflect enhanced exploratory "testing of the ground" movements with sensors of the non-fatigued leg's feet, providing supplementary somatosensory inputs to the central nervous system to preserve/facilitate postural control in condition of altered neuromuscular function of the dominant leg's hip abductors induced by the fatiguing exercise."-*Vuillerme N1, Sporbert C, Pinsault N.

When one prescribes or chooses a corrective exercise for a client, one based sheerly on what is visualized as an "apparently" faulty movement pattern or aberrant screen, one is making many assumptions. Assumptions that are likely not entirely correct (we are being kind, most assumptions made based on partial fragmented information are incorrect to a high degree).

Here is comes again, . . . . what you SEE and TEST in your client's movement is not what is wrong with them most of the time. What you see is how your client is ADAPTING to the variables they can engage, avoiding the ones that are painful or perceived as unstable, or finding ways around immobility and as the article as quote above suggests. This was a basic tenet of Karel Lewit's and Janda's work to not focusing on the area of pain, rather to seek out the root cause, we are just saying it in a different manner.

Continuing, we also adapt around fatigue which can take place even in everyday tasks and how we move around our world, yes, even in our gait. Yes, you are seeing a client's best attempts, ones that are likely deeply rooted and now their new norm, their baseline to base all other patterns off of. Their attempts can be based off of immobility, instability (true or functional), lack of skill, proprioceptive deficits, fatigue (lack of baseline endurance), lack of strength or power. For some clients, forget challenging screens that really test them, heck, we find some athletes do not even have the requisite baseline endurance or strength in a few primary fundamental patterns of which they have built more robust patterns atop of. We all to often read about "robustness" of a skill and pattern and interpret it as a good thing. Robustness can also be build atop of a bad pattern of movement, atop of poor stability patterns.

Thus, asking a client to change that ADAPTIVE norm, based off of what you visualize, based on the working parts available to them, without rooting out the cause, is asking them to compensate around their new norm base of compensation. When done this way, we are merely giving our client armor to their dysfunction, faulty robustness if you will. We are in fact moving further from the remedy. To correctly play this multi-layered game of helping people, one has to examine the client, not just put them through screens and assessments that show us (and them) what they can and cannot do.

There is an awful lot of armchair doctoring going on out there, thankfully it all comes from a good place in the heart's of many good folk. We have so many people come in to see us who have problems and a list of corrective exercises that have been prescribed to them, exercises that clearly have been based off of correcting what is seen in their screens and movements. We discuss their workout patterns, their activities, and hear about how they are attempting to build up their bodies for the apparent good. But all to often, with a client in front of us in pain, we hear the clues that the problem is being exercised around. Meaning, building robustness on top of a dysfunctional base somewhere in their system. Many of these people have been given these exercises as part of their corrective work and strengthening programs at their place (gym, box, trainer, coach etc). Many times there was no in depth hands on examination coupled with screens and gait to root out the cause of why they are moving the aberrant way that they are. We all must commit ourselves to a complete process for our clients. Screens and tests and exercises are not enough. Please read yesterdays post if you have not already, we make our point once again in a video case.

Screen Shot 2018-03-08 at 9.34.29 AM.png

To close this post, we fully acknowledge regularly that we are on the same bus to the same temple of higher wisdom as everyone else that reads these kinds of posts. We write to share, but we write to learn, to dive deeper into our thoughts, to challenge our biases and rooted assumptions through thought experiments, challenging thoughts and old ways that get us into troubled automated patterns of approaching all things. Again, we write to learn. And, part of that learning is accepting our limitations and hearing from others who are wiser in other areas than us, so, please comment and add insight below if you wish. Debates are good, for us all.  Pull up a chair, grab a pint, join us around the hearth for some gab.

Shawn Allen, . . .  the other gait guy.    www.doctorallen.co    &    www.shawnallen.net

"One of the few ways I can almost be certain I'll understand something is by sitting down and writing about it. Because by forcing yourself to write about it and putting it down in words, you can't avoid having to come to grips with it. You might be wrong, but you have to think about it very intensely to write about it. So I use writing as a learning tool. " - Hunter S. Thompson

*Postural adaptation to unilateral hip muscle fatigue during human bipedal standing.

Gait Posture. 2009 Jul;30(1):122-5. doi: 10.1016/j.gaitpost.2009.03.004. Epub 2009 Apr 28.

Vuillerme N1, Sporbert C, Pinsault N.

Pod 135: Part 1: Head over Foot? Where should we put our COM (center of mass)?

Key words: cross over gait, head over foot, HOF, gait, gait analysis, COM, COP, center of mass, center of pressure, step width, sprinting, symmetry, running injuries

This podcast (135) and its soon to launch follow up podcast (136), as the intro explains, comes at the tail end of a series of thought debates between Shawn and Ivo with some folks who have a different view point.  While the debate is unsettled because there is not sufficient research to support one side, we feel the research leans towards our side of things.  However, as the debates went on, it became clear to us that both parties were approaching the debate from a different metric to gauge each party's beliefs.  We outline this in the introduction and then more forward into our dialogue.  We hope you find this a productive thought experiment.
 

Links to find the podcast:

iTunes page: https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138?mt=2

Direct Download: http://traffic.libsyn.com/thegaitguys/pod_135final.mp3

Permalink URL: http://thegaitguys.libsyn.com/pod-135-part-1-head-over-foot-where-should-we-put-our-com-center-of-mass

Libsyn URL: http://directory.libsyn.com/episode/index/id/6309104


Our Websites:
www.thegaitguys.com

summitchiroandrehab.com doctorallen.co shawnallen.net

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.

Do you really need your 5th "pinky" toe ?

This little piggy went to market  . . . . .  as the nursery rhyme goes.

rewind blog post for your enjoyment

Do I Really Need My Pinky Toe?

Just the other day we saw this article in Popular Science written by Sally Zhang.  Sally obviously does not read our blog, but she got a lot of stuff right.

“If you’re born without a pinky toe or have an accident and it’s removed, you can completely do everything you wanted to do,” Dr. Anne Holly Johnson, instructor in orthopaedic surgery at Harvard Medical School, says.

Above you will see a photo of one of the gait guy’s feet.  It is quite clear from the photo that competent use of the pinky toe is not necessary for adequate, and possibly exceptionally skilled, foot function.  Here, check out this video of our foot in these 2 videos (here and here) for some advanced foot function (sans pinky toe). As you can see in the photo above, this 5th toe has likely never felt the ground, this is a fixed deformity.  Flexor and extensor function of the toe are intact, but it does not reach the ground and so assistance in gaining adequate purchase of the 5th metatarsal on the ground is absent. 

This brings us to a deeper question, what about the 5th metatarsal then? Is it necessary ?  Our answer even without deeper research is a solid “yes”. The foot tripod is severely compromised without the 5th metatarsal. The lateral stability of the foot is impaired without the 5th MET.  The natural locking of the calcaneocuboid joint mechanism will be impaired, the peroneal muscles that provide such critical lateral ankle and foot stability will have fascial planes and tendon attachments disengaged, the natural walking gait lateral to medial foot progression would be impaired, propulsion would be impaired and the list goes on and on. And, not even on the local foot/ankle level. Because, if you take out the function and stability of the lateral foot the hip is very likely to suffer lateral (frontal plane) stability deficits. Meaning, the gluteus medius and abdominal obliques will have more difficulty guarding frontal plane drift when in stance phase rendering all of the “cross over gait” risks (link) highly probable.  

So, not much exciting stuff here today. The presence of a functioning pinky toe does not appear to be critical but don’t take away its big brother neighbor, the 5th Metatarsal or trouble is just around the corner. Don’t believe us? Just ask anyone with a non-union fracture (Jones fracture) of the 5th metatarsal.

The answer goes back to the evolutionary history of humans, explains Dr. Anish Kadakia, assistant professor in orthopaedic surgery at Northwestern University. "Primates use their feet to grab, claw, to climb trees, but humans, we don’t need that function anymore,“ Kadakia says. "Clearly we’re not jumping up and down trees and using our feet to grab. We have toes embryologically, evolutionary for that particular reason because we descended from apes, but we don’t need them as people.”

The gait guys, working with 4 toes on each foot, one step ahead of evolution it seems.

Shawn and Ivo,

The gait guys

reference:

http://www.popsci.com/science/article/2013-05/fyi-do-i-really-need-my-pinky-toe?dom=tw&src=SOC



https://thegaitguys.tumblr.com/post/96538178584/do-i-really-need-my-pinky-toe-just-the-other
 

How the CNS adapts. Exploratory testing of the ground.

Screen Shot 2018-02-16 at 8.33.03 AM.png

What is happening at the 150 meter mark in a 200m sprint when that glute starts to fatigue ? What is happening at the 12th mile in a half marathon when stabilzation around that knee starts to falter?
In this article below, the authors discuss postural adaptations to unilateral hip muscle fatigue. This study merely looks at the effects during standing, so imagine what happens during locomotion when things start to fatigue.

Anyone who has sprained an ankle or banged up a knee knows what it is like to have an automated limping gait. The CNS is trying to reduce and shorten the loading response (and time) on the affected limb. This scenario goes on for awhile, days, maybe weeks, until it becomes somewhat more automated.
We just saw a client in the office just yesterday who had a subtle limp from a foot fracture 6 months ago. I mentioned it in passing, "isn't it amazing that your CNS can still be generating that limping adaptive gait even after 6 months, even now that the pain is no longer present?" His response, "What ? I am still limping? No I'm not ! Am I? Really?" I showed him the video, he was shocked. Things get automated, the CNS adapts, and it often doesn't know when to let go of an adaptive pattern even when it is no longer warrented. It is amazing to think that the brain often cannot logically process the incoming data and revert back to the sensory-motor program that was engaged pre-injury. Amazingly, perhaps the brain still knows better, perhaps it knows that things might seem fine, but lurking beneath the surface the sensory receptors are still sending soft warning signs that things still are not kosher.
We say something like this often to our clients, "The CNS makes momentary adaptive choices, but it has no way of foreseeing the consequences of an adaptive measure which is necessary in the moment. It makes these choices based on perceived stability, necessary mobility, economy, and pain avoidance, most of the time. But, it has no way of seeing into the future to see whether its choices have ramifications, it just chooses what makes the most sense in that moment." This is one of the reasons why we get so cranky about people who offer training and corrective exercise queues to people without deep thought, examination, and consideration. There can be ramifications down the road, that, in the present, are unseen and unknown. For example, just because you are running faster because you altered or augmented a client's arm swing, doesn't mean that newly trained pattern, that might even have the positive performance outcomes, won't have consequences that need to be walked back in the future. This is one of the premises of our recent arguments with the HOF (Head over Foot) crowd, who explicitly convey they only care about the clock and a client's speed, not about their well being down the road. There is no free lunch, the piper always gets paid, but just because we are not there to see the payment, it doesn't mean the day of reckoning isn't coming. We have been playing this human mechanic game now collectively for about 50 years, we know the payback is real, we see it often, eventually the tab for that free lunch shows up.

In this article below, the authors discuss postural adaptations to unilateral hip muscle fatigue. We are again looking for that Piper, he wants to get paid, so what is the consequence to the fatigue ? This study merely looks at standing, so imagine what happens during locomotion when things start to fatigue.

"The purpose of the present experiment was designed to address this issue by assessing the effect of unilateral muscle fatigue induced on the hip's abductors of the dominant leg on bipedal standing."

"Results of the experimental group showed that unilateral muscle fatigue induced on the hip's abductors of the dominant leg had different effects on the plantar CoP displacements (1) under the non-fatigued and fatigued legs, yielding larger displacements under the non-fatigued leg only, and (2) in the anteroposterior and mediolateral axes, yielding larger displacements along the mediolateral axis only. These observations could not be accounted for by any asymmetrical distribution of the body weight on both legs which were similar for both pre- and post-fatigue conditions. The observed postural responses could be viewed as an adaptive process to cope with an unilateral alteration in the hip neuromuscular function induced by the fatiguing exercise for controlling bipedal stance. The increase in CoP displacements observed under the non-fatigued leg in the fatigue condition could reflect enhanced exploratory "testing of the ground" movements with sensors of the non-fatigued leg's feet, providing supplementary somatosensory inputs to the central nervous system to preserve/facilitate postural control in condition of altered neuromuscular function of the dominant leg's hip abductors induced by the fatiguing exercise." - Vuillerme et at, 2009

We have discussed arm swing many dozens of times over the 9 years of blogging research on the web. You can search our blog for "arm swing" and go down the deep rabbit hole we have dug if you wish to learn how arm swing is not only necessary, but highly adaptive ballasts to help maintain balance and effective and adaptive locomotion. They can be used for improving or changing locomotion of all types. They can be looked at as prime movers or passive followers of the higher order leg swing. They can be coached right and wrong. The have a huge impact on COM (center of mass) and COP (center of pressure). And as a tangential comment of the article above, when the adaptive postural responses of the body are activated from a given fatigue in the body, COM and COP must change and adapt to keep us upright in the gravitational plane. These COM and COP changes are exploratory postural compensations, of which altered arm swing is often one adaptive and assistive measure. In this articles discussions, these compensations provide supplemental somatosensory inputs to the central nervous system to "preserve/facilitate postural control in conditions of altered neuromuscular function" when fatigue sets in somewhere. Bringing this all full circle, changing someone's arm swing, because you do not like how it looks (ie asymmetry, cadence, direction, etc), is foolish. The brain is doing it, because it likely has to do it to help adapt to a problem elsewhere that is altering the brain's perception of a safe COP and COM. Your job is to find out why and correct it, not to teach them a new way, which is very likely a new compensation to their already employed adaptive compensation.
-Shawn Allen, the other gait guy

Postural adaptation to unilateral hip muscle fatigue during human bipedal standing. Vuillerme N1, Sporbert C, Pinsault N. Gait Posture. 2009 Jul;30(1):122-5. doi: 10.1016/j.gaitpost.2009.03.004. Epub 2009 Apr 28.

Your gait analysis is lying to you more than you think. The more difficult motor program your client is running occurs before the gait analysis even begins.

Screen Shot 2018-01-30 at 7.32.33 AM.png

Even before you client walks back to your treatment room, there are several things that we may not be aware of. Gait initiation is a different and more complex motor program than the simple gait motor program.

Here is a little something we do in our clinics, all the time. When the session room is open for the next client, we greet our client in the lobby. We do not have our staff send them back to the room to change and wait for us. We watch them closely, but without them knowing. How does the client stand up? How do they initiate their gait cycle ? How is their balance? How do they carry their bags, purse, backpack ?
We ask them to head back to the session room to get changed, letting them think we are grabbing a drink of water. And then, in a sneaky manner, we watch them stand, initiate gait, and walk back to the room.
We do this, because, gait initiation is separate motor program. It requires several component parts, a squat, weight shift, double support balance acquisition, COP (center of pressure acquisition), step length precalculations, step width precalculation, foot strike targeting, weight shift again, initial weight transition, and then the gait cycle. And gait initiation is different and asymmetrical in people with pain, we know this for a fact in clients with painful osteoarthritis. These clients develop adaptive posturomotor strategies that shorten the monopodal phase on the affected leg.*
For many gait disorders, these are the component parts that will first show up if there is a problem in the system. Gait initiation is more difficult than gait perpetuation. Besides, how we walk when we do not think we are being watched, when we are carrying our things (purse, phone, bottle of water, backpack, etc) is how we typically walk. Clients will show all the goodies we need to see: the turned out foot, the hiked shoulder, the limps, the staggers, stumbles, speed, step width, and the like. We also get to see how they move in the shoes they live in, the heeled ones, the broken down ones, the work shoes.

So, when your client is having a formal treadmill gait analysis, what are you seeing? Their best behavior, or the truth ? One thing is for sure, you do not see the most important program the precedes their treadmill analysis, namely, how they get out of the chair and up onto the treadmill. This stuff matters.
There are clues everywhere, grab all of them, in as natural a manner as possible.

The Gait Guys

*Arch Phys Med Rehabil. 2000 Feb;81(2):194-200.
Asymmetry of gait initiation in patients with unilateral knee arthritis.
Viton JM1, Timsit M, Mesure S, Massion J, Franceschi JP, Delarque A.

The Pelvis and COM in locomotion.

"Biomechanics of unobstructed locomotion consists of synchronized complex movements of the pelvis, torso, and lower limbs. These movement patterns become more complex as individuals encounter obstacles or negotiate uneven terrain."

This data was taken on 10 healthy young adult individuals investigation specifically the mechanics of the pelvis, torso, and lower limb segments and how they relate to obstacle negotiation of varying sized objects combined with temporal constraints to perform the task.

The data "revealed a significant increase in sagittal (posterior tilt) and frontal (ipsilateral hike) plane pelvic angular displacement and higher sagittal plane posterior torso lean angular displacement with increased obstacle height. Furthermore, both sagittal plane hip and knee maximum joint flexion were significantly higher with increasing heights of the obstacles during negotiation."

https://www.ncbi.nlm.nih.gov/pubmed/28297177