Podcast 114: Pooping your pants

This podcast is big on the neurology of  motor control and movement, plus more on glutes and quads, runners diarrhea and lots of other good stuff.  Join us today !

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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).
 
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_______________________________________
Show Notes:
Motor control and the immune system.
http://www.thegaitguys.com/thedailyblog/2016/9/12/motor-control-and-the-immune-system

The Exercise Drug is on its way.
http://qz.com/783958/scientists-have-created-a-drug-that-replicates-the-health-benefits-of-exercise/

http://www.cell.com/cell-reports/pdf/S2211-1247(16)31051-8.pdf
 
Glutes and Achilles.
http://www.thegaitguys.com/thedailyblog/2016/9/28/david-and-goliath-the-calf-and-the-glute

https://www.ncbi.nlm.nih.gov/pubmed/24121244

More glutes and quads
 http://www.thegaitguys.com/thedailyblog/2016/10/5/who-rules-the-glutes-or-the-quads-well-it-is-complicated

Runners Diarrhea. What's up with that ?
Am Fam Physician. 1993 Sep 15;48(4):623-7.
Runner's diarrhea and other intestinal problems of athletes. Butcher JD1.

gut and zonulin full text link     https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4589170/

2012 article here: http://www.karger.com/Article/Abstract/342169

Case: Forefoot pain from achilles repair.

Gentleman came in, several month history of left forefoot pain and plantar foot cramping after long walks and long bikes or sessions on the indoor bike trainer.  Typically clipped in.  Notable, left calf atrophy (see pic) from a 30 year old achilles repair.  Terminal Heel rise is impaired and weak and challenged calf endurance.  Left calf is also short, obviously.

Exam found notable over recruitment of the long toe flexors (also off that posterior compartment) -- afterall, someone in that posterior compartment has to be creating propulsion and heel rise (even that is a long shot of a strategy for the long toe flexors).  

Long toe flexor overactivity causes toe hammering, inhibition of the short toe flexors, distal migration of the metatarsal fat pad and inhibition of the lumbricals.  

Translation: overburden of the forefoot in loading, both from fat pad migration, lumbrical inhibition and premature heel rise (from short calf-achilles and atrophy, and altered heel rise strategy as noted above). 

The metatarsals are small bones -- they don't mind loading but it has to be clean appropriate loading to repetitively endure it without problem. Forefoot loading can be a challenge when the mechanics are off. The lumbricals are part of this scenario -- if they are weak or inhibited proper posturing of the forefoot during forefoot loading is compromised and the ability to stabilize the toe is flawed (this is a common problem in hammer toes (functional or anatomical)).

One has to get to the root of the problem on this one . . . . the old achilles trauma and weak calf. Its been 30  years.  Time to dig in on this one, start with the basics, and look at a long calendar for change.

Just some quick thoughts on this case that walked in today.  Forefoot pain -- it can be complicated. 

Oh, and guess what else was off ?  Yup, hip extension and gluteal-hip stability. Duh.

- Dr. Shawn Allen, the other gait guy

Failure to Adduct the hip in symptomatic runners with iliotibial band syndrome.

This is an interesting finding. They took symptomatic iliotibial band runners and looked at the hip adduction as they fatigued. When they found was not what one might initially expect, meaning more hip adduction because of the fatigue. Instead, they found was that when exerted, the female subjects independently modify their running gait to decrease hip adduction, potentially as a result of pain....... they compensated to protect. Not earth shattering, but support for the neuroprotective biomechanical mechanisms. This is how we all find a way to keep going, we find away around the problem. The problem here is that by the time they come to see us for care, we may be hearing of the next level of compensatory break down, and not the primary issue.

https://www.ncbi.nlm.nih.gov/pubmed/27718393

And then there is # 245....

Look at the position of his knee with respect to his foot. Both are pointing outward into external rotation. They are in the same plane so a torsion is unlikely, but he is probably trying to gain some stability as his center of gravity moves across his body.

Now look at his pelvis and see how it is tilted (or dropped) down on the left. We would definitely want to check his right gluteus medius and his left quadratus lumborum.

And what about that arm swing? Is he creating more space on the left (ie abducting his left arm) from his body lean to the right? More than likely, this is to make up for his hip muscle problem. we say this because his head tilt is to the left. Remember that your body will always try to make your visual fields parallel with the ground, so as his body goes to the right, his head will go to the left. There must be a great deal of body rotation going on, as his entire jersey has moved to his right!

Whoa # 2

And what about # 260?

Things are certainly different for this chap compared to # 172. His take off from his right foot looks pretty good. His left foot looks like it is going to cross over with some medial knee fall as it descends to hit the ground. Just before it hits the ground, it should be supinated in some degree of dorsiflexion (he is sprinting, so we expect some plantar flexion because he is sprinting), inversion and adduction. His pelvis is nice and level. His arm swing looks pretty good with only a slight cross over on the right as it is coming through. With form this good, no wonder he is out front!

Whoa!

Whoa! What's wrong with #172?

 Where do we start? Look at all of that tibial and genu varum! Notice how his knee is outside the sagittal plane? This means that he also has internal tibial torsionand he is rotating his foot out to create the requisite 4-6° internal rotation needed to move forward. It also looks like he has limited internal rotation of the thighby the positioning of his body.  This could be due to femoral retroversion as this commonly occurs with internal tibial torsion. Check out the interesting hand posturing bilaterally. Notice the extended thumb and wrist on the left? He may be trying to fire into his extensor pool to help gain more hip extension.  I sure wish we had a Sideview. Thankfully his pelvis is relatively level, isn't it? No, it actually isn't. That's just his shirt. Look closely at the tops of the iliac crests and you will see what I am talking about. Did you catch the slight head tiltto the right? With that much tibial and genu varum his center of gravity is moving to the left and he needs to tilt his head to the right to equalize things out.  What about the posterior rotation of the left shoulder? Again probably this is due to a lack of or failure to use internal rotation of the left hip.

Lots to talk about on this picture and we will do some more next time.

What internal tibial torsion and tibial varum looks like in a world champ.

You can be an effective athlete with internal tibial torsion and tibial varum.

The video of world champ Mirinda Carfrae shows it beautifully on the right side during loading. The question is always, "how durable is your given anatomy ?". 

How durable is your compensation ? And is there a cost when your endurance runs outor when the load gets too high ?  Those are the big questions you have to ask.

In this video, stop the play at 34-37 seconds, keep playing that loop over and over again until you can clearly lock this in your head -- internal tibial torsion and tibial varum.  See how far laterally she appears in initial weight bearing ? See the appearance of her apparent "in-toe"?  You cannot correct this. You would be a fool to tell them to toe out more -- this would take her knee outside the sagittal plane. You leave this one alone. You make your athlete durable, giving them frontal plane and rotational-axial plane work to control those torsional forces during loading and unloading.  The difference been you and her, is she has done this loading a trillion times, safely and built durability on the entire chain from foot to spine so the tissues can tolerate it. The question is, will there be a limit for her ? Will there be a point where the bone and soft tissues say they have had enough ?  This is the golden question. 

Some folks with this can be assisted by more step width separation, getting away from a Cross Over gait but Mirinda has a beautiful running form.  However, in this particular video so does show some cross over gait, very narrow foot separation, and this magnified what you are seeing during her foot strike.  In many other videos she does not cross over if you have studied her running form elsewhere.

As she says in her video, being a world champ is all about the details, details like we pointed out here today.

Know your anatomical variances. Know how they play out, and how they fail.

Shawn and Ivo, the gait guys

Podcast 113: The Hip-Ankle "Z" angle, It is all you need to know.

Plus:  Bringing together hip extension, ankle dorsiflexion, looking at the 6 locomotion compensations to strategize around impaired ankle dorsiflexion during gait/running.

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, Soundcloud, and just about every other podcast harbor site, just google "the gait guys podcast", you will find us.

Here are our local server links:

http://traffic.libsyn.com/thegaitguys/pod_113f.mp3

http://thegaitguys.libsyn.com/podcast-113-the-hip-ankle-z-angle-gait-compensations

Show links:
Exercise releases hormone that helps shed, prevent fat

https://www.sciencedaily.com/releases/2016/10/161004130812.htm

Lifelong strength training mitigates the age-related decline in efferent drive.

Unhjem R, et al. J Appl Physiol (1985). 2016.
http://www.ncbi.nlm.nih.gov/m/pubmed/27339181/

Telemeres and aging
http://well.blogs.nytimes.com/2015/10/28/does-exercise-slow-the-aging-process/?_r=0&module=ArrowsNav&contentCollection=Health&action=keypress&region=FixedLeft&pgtype=Blogs

Using Virtual Reality in Paraplegics:
https://www.theguardian.com/science/2016/aug/11/brain-training-technique-restores-feeling-and-movement-to-paraplegics-virtual-reality

Above ankle brace:
https://www.edgemobilitysystem.com/products/brace2play-above-the-joint-ankle-brace?variant=21314299587

Weak toe grip strength
https://www.researchgate.net/publication/304271421_Weak_TGS_Correlates_with_Hallux_Valgus_in_10_12_Year_Old_Girls_A_Cross-_Sectional_Study

Altra Lone Peak 3.0
https://www.altrarunning.com/men/lone-peak-3-neoshell-mid

3 points to use with ankle instability

In this study they stimulated 3 points: ST41, BL60 and GB40. Take a look at their locations (above). ST41 is at the base of the long extensor tendons; gee, we never emphasize long extensor function, do we? GB 40 is at the lateral malleolus between the peroneus longus/brevis and peroneus tertius; how important are these for coronal plane stability, not to mention the ability to descend the 1st ray. BL60 is just anterior to the lateral malleolus, right by the peroneus longus and brevis (again). Could they have included K6, under the medial malleolus and near the long flexors? Sure. How about SP4 or 4, in the substance of the flexor hallucis brevis and anterior to the extensor hallucis longus. Of course. You can probably think of other points to include as well.

Do you think it was by accident that their muscle selection included dorsiflexors (excepting the peroneus longus) and everters? How about a muscle that would help descend the 1st ray and complete the medial tripod? Hmmm... There is always a reason and a rationale....

"CONCLUSION: Electroacupuncture can effectively improve the proprioception of athletes with FAI and achieves a superior efficacy as compared with the conventional physiotherapy."...or in this case, low level e stim to the medial and lateral malleolus.

How about adding these points, no matter how you would like to stimulate them, to your CAI toolkit?

Zhu Y, Qiu ML, Ding Y, Qiang Y, Qin BY. [Effects of electroacupuncture on the proprioception of athletes with functional ankle instability]. Zhongguo Zhen Jiu. 2012 Jun;32(6):503-6.

History shows...Keep it Simple... Even with those foot exercises

Being a foot nerd, certain things have a tendency to provide entertainment for me. One such thing was a recent article that was published in Foot and Ankle Surgery about the history of military flat foot care. Review of this appeared in one of my favorite journals: lower extremity review.

There was nothing earthshaking in the article other than the emphasis on function was made throughout the article. Exercises were emphasized (though I really don't like the toe flexion ones). And that was an interesting quote from the article

"Far more emphasis should be placed on the functioning of the foot, during the activities that need to be undertaken rather than the height of the arches alone".

They go on to describe a simple exercise where during a march is (is that were often required to do during WW1) people were instructed to keep their toes pointed straight ahead and shift the knees out words to offload the weight laterally. In that particular study, 75%of the people return to their groups and 54% were able to go back to full duty. All with some simple, straightforward instruction.

The lower extremity review article emphasizes intrinsic muscle strengthening for condition such as plantar fasciitis, Hallux valgus and lesser toe deformities. I would have to say that I couldn't agree more :-)

So goes the life of a foot nerd…

Nearly MT J Foot Ankle Surg. 2016 May-Jun;55(3):675-81. doi: 10.1053/j.jfas.2016.01.028. Epub 2016 Mar 12.

Music to my ears....and steps to my cadence

image credit: http://www.holabirdsports.com/blog/which-type-of-music-is-best-for-running/

This piece is a little different. More of an essay or narrative. We hope you enjoy it...

It was 12° when I woke up. It was mid October and fall is in full swing with the leaves still turning and left on many trees. I looked at the thermometer and it read 12°. When I looked outside I could see that 2 to 3 inches of fresh snow had fallen. Electing not to ride my bike because of the slipperiness of the snow on the roads, I donned my Altra’s and headed out for a run. I grabbed my iPod on my way out the door and queued up Nickelback's "All the Right Reasons".

It's amazing how much music can influence your work out. "Follow You Home" came on came on just as I approached the first hill. The song has a relatively strong beat which made me work harder to get up. This made me think of how much cadence can be influenced by music (1-3) and a few pieces we wrote on music therapy. 

Faster cadences have been associated with shorter step length and decreased vertical impact loading rates, in other words less force and theoretically at least, less injuries (4,5) . 

The snow was soft and forgiving beneath my feet and despite wearing tights and two layers on top, I was quite comfortable. “ Fight for All the right reasons" came on as I started my first set of lunges. I could feel my pace again matching the music.

I was making "first tracks of the season" in the snow. That brought a smile to my face. It was quiet and peaceful (except for my music through the headphones of course) and it was feeling like the beginning of a great run. I begin my ascent of the second large hail and “Photograph” came on which made me think about all things high school and brought a smile to my face. I wondered about some of the people I dated as well as a few that I probably should have dated and those that I definitely should not have dated :-)

My run continued, quite well I might add, with some quick intervals of lunges and squats throughout. “Next Contestant” finished up by brief workout as I came down the home stretch. Another smile came to my face as I know what my next blog piece would be about : )

If you just want the bullet, then here it is: “The applicable contribution of these novel findings is that music tempo could serve as an unprompted means to impact running cadence. As increases in step rate may prove beneficial in the prevention and treatment of common running-related injuries, this finding could be especially relevant for treatment purposes, such as exercise prescription and gait retraining.

• Music tempo can spontaneously impact running cadence.
• A basin for unsolicited entrainment of running cadence to music tempo was discovered.
• The effect of music tempo on running cadence proves to be stronger for women than for men.”

1. Van Dyck E, Moens B, Buhmann J, et al. Spontaneous Entrainment of Running Cadence to Music Tempo. Sports Medicine - Open. 2015;1:15. doi:10.1186/s40798-015-0025-9. link to full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4526248/

2. Lima-Silva AE, Silva-Cavalcante MD, Pires FO, Bertuzzi R, Oliveira RS, Bishop D.  Listening to music in the first, but not the last, 1.5 km of a 5-km running trial alters pacing strategy and improves performance. Int J Sports Med. 2012 Oct;33(10):813-8. Epub 2012 May 16.

3. Bacon CJ, Myers TR, Karageorghis CI. Effect of music-movement synchrony on exercise oxygen consumption. J Sports Med Phys Fitness. 2012 Aug;52(4):359-65.

4. Baggaley M, Willy RW, Meardon S. Primary and secondary effects of real-time feedback to reduce vertical loading rate during running Scand J Med Sci Sports. 2016 Mar 19. doi: 10.1111/sms.12670. [Epub ahead of print].

5. Lyght M, Nockerts M, Kernozek TW, Ragan R. Effects of Foot Strike and Step Frequency on Achilles Tendon Stress During Running. J Appl Biomech. 2016 Aug;32(4):365-72. doi: 10.1123/jab.2015-0183. Epub 2016 Mar 8.

Step rate to change foot strike?

Do you do gait retraining? Have you thought about manipulating step rate to change foot strike? If not, you may want to check this out. 

"The intent of our study was to determine whether step-rate manipulation alone was enough to change foot-strike pattern in shod recreational distance runners. We found increasing step rate above the runner’s preferred rate by 10% was successful in changing foot-strike pattern from a heel-strike to a midfoot- or forefoot-strike pattern in 17.5% of the runners, while increasing step rate by 15% changed foot strike pattern in 30%. These results suggest step-rate manipulation alone may be an effective way to change foot-strike pattern in a small percentage of shod distance runners."

http://lermagazine.com/…/step-rate-manipulation-and-foot-st…

Cadence?

More on cadence and running. Increasing it as little as 5% seems to decrease vertical loading rates in the achilles tendon. How can you do that? How about some music or a metronome?

"Rearfoot strike patterns had less peak AT stress (P < .001), strain (P < .001), and strain rate (P < .001) compared with the forefoot strike pattern. A reduction in peak AT stress and strain were exhibited with a +5% preferred step frequency relative to the preferred condition using a rearfoot (P < .001) and forefoot (P=.005) strike pattern. "

Lyght M, Nockerts M, Kernozek TW, Ragan R. Effects of Foot Strike and Step Frequency on Achilles Tendon Stress During Running. J Appl Biomech. 2016 Aug;32(4):365-72. doi: 10.1123/jab.2015-0183. Epub 2016 Mar 8.

Bend-AR 30 Hour Adventure Race

One of our clients, is a badass. He just completed, and successfully we might add, right behind the world's best we are told, just finished this mind boggling race. 

This 30-hour race is now in its sixth year, BEND-AR is quickly becoming a “must do” race and has drawn teams from as far away as the east coast, central Canada and SoCal.  Though the exact course is kept secret up until right before the race date, the event is held near Bend, Oregon. It is touted as being “the must-do race for the Pacific Northwest”.

Disciplines: Mountain biking, whitewater paddling, trekking, and navigation.

That is a long day's work. Congrats to you Luis and to your sponsors !

A unique version of the circumducting gait.

It is Rewind Friday:
Chef and general overall badass Anthony Bourdain's gait.
A unique variation on the Circumducting Gait. You will see this one is many people, if you look for it.

https://thegaitguys.tumblr.com/post/21713480315/the-chef-another-abnormal-gait-pattern-in

The Chef: Another abnormal gait pattern in celebrity chef and The Travel Channel’s Anthony Bourdain.

It was just a few nights ago after a 13hour day with patients that I got home and climbed into bed, looking forward to flipping through channels to find something to alter my brainwave state. I needed to find something that would allow me to dial down into a slumber.  Much to my happiness I found one of my favorite shows, “No Reservations” with my favorite chef.  I get a real kick out of Tony. This is one smart dude. He is pretty slick with the english language.  Did you ever get to read his New
York Times best seller “Kitchen Confidential”?  What a killer book. We recommend the audio book read by the author himself.  It turned the restaurant scene upside down.  Has anyone ever told you not to order fish Monday through Thursday ? It is all in the book.  Why else do I love Bourdain?  His command of the english language is exceptional, and creative.  For example, he once said, “what would it be like to be a meat-filled Pinata at a Pit Bull convention?”.  Things like that stick with you.

Anyhow, so there I am lying in bed dozing off, listening to Bourdain talk about Mozambique and there he is in all his slender glory walking down the street with his sidekick Samir.  “Red Alert, Red Alert ! "  The clinical brain snaps back on.  Dammit !  Knowing very well I had to rewind the cable box to see it again, but knowing I was slowly descending into deeper brainwaves, I quickly rewind and grab my iphone to record the gait you see above.  You see, when you are a gait nerd like us, nothing escapes you when it is this obviously wrong. It is a disease; trust us.  We cannot go anywhere anymore without noticing pathologic gait.  It appears we cannot even watch a cooking show. And since we live on a planet where everyone walks, it must be a penance for something we must have done in another life.

Onto Bourdain’s gait. 

Look at Tony’s circumducting feet compared to Samirs (on the right).  Samir clearly engages pelvis lift on the swing leg side which is typically brought on by engagement of the hip abductors (g. medius) on the stance leg side. This lift on the swing side allows the swing leg to have ample room to pendulum through without having to prostitute the knee or foot posturing.  The knee and foot simply sagittally hinge through, this is economical gait.

Bourdain on the other hand shows little if any swing side pelvis lift driven by stance leg hip gluteus medius engagement.  This creates a clearance problem for the pendulum swing leg.  So now the problem becomes how to get the leg to swing through without catching the toes and foot. You must create clearance. Clearance can be obtained by:

generating oppositehip abduction forcing the swing leg hemi-pelvis to lift
increasing hip flexion which will initiate a steppage gait. This will be combined with increased knee flexion. This is productive and necessary if you are climbing stairs or trying to unload a painful turf toe near the end of stance phase push off.  When seen in normal walking gait it may represent neurologic pathology.  But folks with hip problems or weakness will use it to get around to avoid tripping.
circumduct the swing leg hip. The act of swinging the leg outward and around will eat up the leg length.
circumduct the foot.

Bourdain is doing #4. It is a pretty lazy gait strategy, you can see it is lazy. It probably requires very little energy to flip the foot outside the normal ankle dorsiflexion foot swing progression.  What must be the cost to activating the peronei and the lateral toe extensors to flip that foot around like that ? Sure you can see that the knees are for a moment carried outside the sagittal plane but who cares, right ? 

There are a couple of concerns. One is that failure on a single step to generate sufficient foot/ankle circumduction will result in a foot catch and a fall.  Another is the trouble in always getting that circumducting foot to land precisely in the near sagittal plane. When you move the foot on an arc you really only have a narrow target to land the foot within the 5-15degree landing zone. Circumduct too far and the foot is in-toed and more rigid due to it being supinated during midstance, circumduct too little and the foot is more out-toed and increased pronation risk increases.  This goes for running as well.

Go back and watch Samir’s walk. Clean and done right, the swing leg is a passive pendulum. Tony’s is obviously different. Who knows, maybe he has bad hips ? Maybe it was always a struggle to walk normally. He is 6'4” so we cannot blame it on excessive height unless he lives in a house that has 6 foot ceilings, because then his strategy would be our gait of choice. It would be the only one that would effectively work !  Maybe that is it. Maybe he lives in Smallville ?

We don’t think so.  The only for sure way to know would be to get him on our exam table and see what parts he is not using. We would put big money on weak gluteus medius, bilaterally.  It is the one we see most often in this abnormal gait pattern.

Shawn and Ivo, tortured gait observers in a world of ambulatory pathology.

Welcome to our hell.

Another way to alter loading rates and potentially reduce injuries?

How about providing something a simple as visual and auditory cues?

In his particular study they cued people to either
1. Forefoot strike
2. Decrease average vertical loading by 15% or
3.Decrease step length by 7-1/2 per cent (ie increase step frequency)

All 3 decreased eccentric knee joint work; but increased ankle joint work. Forefoot strike as well as cues to decrease average vertical loading (which would cause you to forefoot strike) increased ankle joint work. I guess that if you steal from Peter you need to pay Paul! Decreasing step length had no adverse effects.

What are you trying to accomplish? If it is decreased knee joint loading, such as in patients with patellofemoral problems, then this could be a very good thing. If you have a patient with a raging achilles tendinitis, then perhaps not.

Having someone decrease their step length (effectively increasing their cadence) can be one of the safest ways to decrease vertical loading rates.

Baggaley M, Willy RW, Meardon S. Primary and secondary effects of real-time feedback to reduce vertical loading rate during running Scand J Med Sci Sports. 2016 Mar 19. doi: 10.1111/sms.12670. [Epub ahead of print].

A Metabolic Cost to the Cross over gait.

Here is what we know, when we put our foot on the ground, we, as humans who sit too much and tend to get into sagittal plane activities too often, things like swimming, biking, walking, running -- and do not challenge the frontal/lateral plane enough earn our way into functional problems:  "Walking appears to be passively unstable in the lateral direction, requiring active feedback control for stability. The central nervous system may control stability by adjusting medio-lateral foot placement, but potentially with a metabolic cost. This cost increases with narrow steps and may affect the preferred step width." -Donelan study

For well over 6 years now I have been working on solidifying my thoughts and theories on the cross over gait. I did our 3 part video series back in 2011 and Ivo and I have built our theories to deepen the roots on this concept since then. Since then, the more research I come across continues to serve these initial theories well and help me to hone them for my clients and runners. Some still dismiss the concept because "many professional runners have a very narrow step width and they are fine" -- that is not the point, it is deeper than that. More recently I have found it more helpful to explain it as, "a narrow step width, like all things off of the mechanical norm, have a place and some value when the environment requires it. However, it comes down to a challenge between the two issues of Economy and Liability, perhaps better put, Economy vs Stability. A  narrow step width may be more economical for moving through the sagittal plane in many ways, if they have sufficient lateral (frontal plane) endurance, but if one goes too far or for too long, that economy can become a liability and injury risk can build as one begins to tease that lateral plane."  I will ask my athletes, "how long can you be in this running economical place before you run out of gas and liabilities start to mount into the more metabolically demanding frontal plane?".  Endurance and strength are the major factors, built on skillful movement. The question remains for many athletes, "how long can you run with a narrower step width, with your present lateral hip-pelvis-core endurance and stability, before you exhaust the endurance of your protective mechanisms and expose the liabilities of those more risky frontal plane mechanics ?"

Again, from the Donelan study:
"Walking appears to be passively unstable in the lateral direction, requiring active feedback control for stability. The central nervous system may control stability by adjusting medio-lateral foot placement, but potentially with a metabolic cost. This cost increases with narrow steps and may affect the preferred step width. 
These results suggest that (a). human walking requires active lateral stabilization, (b). body lateral motion is partially stabilized via medio-lateral foot placement, (c). active stabilization exacts a modest metabolic cost, and (d). humans avoid narrow step widths because they are less stable."

- Dr. Shawn Allen, one of the gait guys

J Biomech. 2004 Jun;37(6):827-35.  Mechanical and metabolic requirements for active lateral stabilization in human walking.  Donelan JM1, Shipman DW, Kram R, Kuo AD.
 

Welcome to the posterolateral corner (PLC) of the knee: The Dark Sleepy Hollow of post ACL knees.

Although perhaps more commonly thought to be found in PCL injuries, i personally cannot tell you how many cases of ACL repair I have seen over the years that turned into a failed surgical response because damage and laxity in the posterolateral corner of the knee was missed. 
 I have sent enough knees back to surgeons with detailed explanations of a discovered PLRI (posterolateral rotatory instability), some impressed that it was found, others dismissing it (and eventually surgery by another doctor). These are frustrating cases and they cannot be missed.  One must not just assess for the ACL tear, post event tear is an optimal time to determine if there is BOTH a positive drawer phenomenon and a pivot shift. The majority of PLC injuries do not occur in isolation and are part of a more complex injury pattern that typically involves other vital supporting structures. Do not dismiss the restraining capabilities of the capsular and non-capsular secondary restraints in this far corner of the knee. Finding the pivot shift after the ACL reconstruction is just too late, you must catch it before it heads to surgery and make sure the surgeon knows that the posterolateral corner restraints were also trashed. They likely need repaired as well. otherwise the client will have a great tight drawer test post surgery but will have rotational instability, which is arguably worse if you ask me.  If you find PLRI on the exam make a strong note of it on the MRI request, be sure the radiologist has the clinical functional info in mind when they get the static images coming up on the screen.
Too many clinicians do not know how to assess this area, and the pivot shift phenomenon is also overlooked and misunderstood. If you have never likely had someone walk you through what a positive pivot shift feels like on a ACL knee you will not know what it feels like in a post ACL reconstruction that is failing rehab.
"Although rare, posterolateral corner (PLC) injuries can result in sustained instability and failed cruciate ligament reconstruction if they are not diagnosed. The anatomy of the PLC was once thought to be perplexing and esoteric-in part because of the varying nomenclature applied to this region in the literature, which added unnecessary complexity. "- Rosas
"More recently, three major structures have been described as the primary stabilizers of the PLC on the basis of biomechanical study findings: the lateral collateral ligament, popliteus tendon, and popliteofibular ligament. " 

Do not miss this one gang. Know how to test and feel for PLRI, you will find it if you start looking for it. And, you will likely fail in rehabilitating these knees, it usually need surgical correction of that corner.

- Dr. Shawn Allen, one of the gait guys

Radiographics. 2016 Oct;36(6):1776-1791. Unraveling the Posterolateral Corner of the Knee. Rosas HG1.
 

Acute tendon changes in intense CrossFit workouts

Study: Acute tendon changes in intense CrossFit workout

Habitually overloaded tendons often thicken and increase the tendonopathy risks -- nothing new here.
However as this study points out "it remains unknown whether acute overload caused by strenuous, high-intensity exercise will exert changes in tendons and if these changes can be detected and described by ultrasonography."

This study (note: Achilles, and plantaris tendon ultrasounds were performed before and after a specific workout in 34 healthy subjects)
. . . .noted "a significant increase in the thickness of the patellar and Achilles tendons" in response to strenuous, highly intense CrossFit exercises. Cross fit is not the culprit here, it is the load and load rate. None the less, it is good to know that an aggressive workout can leave us more vulnerable. This is why adequate rest and recovery must be part of your regular weekly workouts. One cannot keep fully stomping on the gas pedal over and over, workout after workout, and not expect problems to creep in if adequate recovery time has not been afforded to the working parts. This study showed changes after just one workout. No rocket science here today, we should see changes, load was applied. This is just good old fashioned "well duh, that makes sense". Here is the problem, we don't always listen to logic, nor do our clients who have goals and timeframes. We live in the "more is better" world now, so stay vigilant on logic gang. Dial your foolish clients in a little, save them some grief.  Yes, this goes for runners and all other venues of activity, there is a reason why we see problems in people with speed workouts more frequently than base miles.

Acute tendon changes in intense CrossFit workout: an observational cohort study. F. Y. Fisker et al
http://onlinelibrary.wiley.com/doi/10.1111/sms.12781/full

More foot exercise studies to confuse you.

Don't necessarily believe all that you read. Please to not take away from this study that these 4 exercises: short-foot exercise, toes spread out, first-toe extension, second- to fifth-toes extension are golden goose exercises to rehab your athlete. On first glance if one is not thinking, that could be a mistake in translation.

"The intrinsic foot muscles maintain the medial longitudinal arch and aid in force distribution and postural control during gait."  That is a pretty bold statement by the study's authors. We would argue that a far less misleading statement would be that "the intrinsic foot muscles are a piece of the puzzle, just a piece, and to dismiss the powerhouse tibialis anterior, tibialis posterior, long and short toe flexors and particularly the extensors is a glaring oversight".  Yes, I know, the authors just wanted to study the intrinsics, I get it, -- one just has to be careful of the conclusions made when the study is so microscopic compared to the global perspective at hand.  Please, read on.

This study tried to correlate the effects of these 4 exercises: short-foot exercise, toes spread out, first-toe extension, second- to fifth-toes extension on activation of the foot intrinsics muscles they chose to observe (abductor hallucis, flexor digitorum brevis, abductor digiti minimi, quadratus plantae, flexor digiti minimi, adductor hallucis oblique, flexor hallucis brevis, the interossei, and lumbricals).

They looked at the activation before and after exercise in just 8 athletes. They did not look at non-athletes and yes, this is a terribly small N sampling and the study only used T2 weighted MRI to make these conclusions.

The study's conclusion was "Each of the 4 exercises was associated with increased activation in all of the plantar intrinsic foot muscles evaluated.".  

Here is my concern*. 
Did they consider the various foot typings ? (*Caveat, I have not read the entire study, I am trying to get it). There are many variables to consider including arch integrity, forefoot type, rearfoot type, foot flexibility, step width, step length, client weight amongst other things. Yes, that makes for a near impossible study, I get it. And, it does not appear they had a control study that looked at what happened right after walking. Wouldn't it be fair, and wise,  to see what the study showed after barefoot walking for 1-2 minutes ? I bet many of these muscles show significant activation there as well, after all, they were weight bearing and stepping down on the foot which requires the muscles to be activated and utilized.  So, does that then mean these 4 exercises are any better than walking ? Does that mean they will suffice for homework for your client ? Does that mean they will strengthen these muscles ? And, does activation mean proper pattern utilization of these muscles, meaning, is there functional translation over to functional use ? Yes, that is not what the study was looking at, but for darn sure that would have been nice info to know. Just take the study for what it found, and do not step beyond those tiny boundaries. We hope that is what they will go for in the next stage of study.  To be fair, they also concluded, "These results MAY have clinical implications for the prescription of specific exercises to target individual intrinsic foot muscles."  Safe words. Yes, I capitalized the word MAY.

- Dr. Shawn Allen, one of the gait guys.

Thomas M. Gooding, Mark A. Feger, Joseph M. Hart, and Jay Hertel (2016) Intrinsic Foot Muscle Activation During Specific Exercises: A T2 Time Magnetic Resonance Imaging Study. Journal of Athletic Training In-Press. 
http://natajournals.com/doi/abs/10.4085/1062-6050-51.10.07
http://dx.doi.org/10.4085/1062-6050-51.10.07