Some more really subtle things...How sharp are YOUR eyes?

As I study this video more and more (yep, we just keep looking at things because we are that nerdy and that paranoid that we missed something) I saw at least 3 very subtle findings. 

Watch the video of this right handed physical therapist who had L knee reconstruction (MCL/ACL with hamstring allograft) a few (hundred) times and see what you come up with, then come back and read this. We lie to slow things down and even frame by frame it with the slow motion feature or space bar to stop it. As background to the clinical exam, he has limited hip and knee extension on the left, 4/5 weakness of the quadratus femoris. His popliteus tests strong and 5/5. He has right sided back pain with L sided knee pain at the joint line and just inferior and medial. the treadmill is at a 2% grade at 2 mph.

Notice how he has a pelvic drift to the right during stance phase on that side. Why do you think? Remember, he has had a left sided knee surgery that left him with limited knee extension on that side. This creates a functional short leg on that side (the left), so he needs to get the longer (right) leg around. We don’t always see lateral movement of the pelvis on the longer leg side, but our guess is he is trying to “shorten” the longer leg side; lateral translation in the coronal plane is one strategy to accomplish that.

Now look at the left side. Can you see the subtle hip hike to clear the right leg? How about the small amount of circumduction? Sometimes folks will employ more than one strategy to get around a long leg, but ususally one will predominate, but not in this case. 

Did you catch the abductory twist of the right heel? The longer leg side needs to go through a greater range of motion of ankle dorsiflexion which will store more potential energy in the tricep surae as well as long flexors of the toes, that energy needs to go somewhere!

Now think about step length. It will often be shortened on the shorter leg side. He still needs to move forward the same amount, so he uses the right arm to help propel his center of mass forward. Do you see the increased arm swing? 

And why does he abduct his right arm so much? Where is his center of mass at left foot strike? It is all the way to the right, because of the “short leg”, correct? How can you counterbalance that? Abducting the arm would certainly accomplish that. Why does it go across the body? It is no longer needed to be that lateral during stance phase on the right, but he still needs to use it to propel himself forward with the shortened step length we talked about before. 

Mental gymnastics, running through what runs through our minds and why things may appear the way that they do. A great lesson in knowing what is supposed to happen and when in the gait cycle

Dr Ivo Waerlop, one of The Gait Guys

#kneepain #lowbackpain #gaitanalysis #thegaitguys #visualgaitanalysis

Support for visual gait analysis... with respect to leg length discrepancies

image credit:

image credit:

We talk about leg length discrepancies all the time here on the blog and sometimes, how small discrepancies cause changes in peoples biomechanics. The gold standard for measuring a leg length difference is full length lower extremity X ray, but this presents a problem due to the ionizing radiation, accessibility as well as impracticality of X rays every person with a suspected difference.

We have talked about different compensations as to how to get around a leg length discrepancies. Last week we actually did a tell a seminar on this entire subject. Your patient or client needs to “create clearance” for the longer leg side. This can be accomplished in many ways.

The 5 most common strategies (keep in mind there are many more) are:

  • lean the torso to the short leg side (essentially hip adduction of the longer side)

  • hike the torso on the long leg side

  • circumduct the longer lower extremity

  • increase plantar flexion of the calf of the short leg side

  • increase hip and knee flexion on the longer leg side

And that is exactly what this study found. They looked at kinematics in people with anatomical leg length discrepancies and found that hip adduction as well as increased hip and knee flexion were 2 variables that were consistent in folks with anatomical differences and suggest these variables are a useful screening tool.

Paying attention to how people move and looking for asymmetries. In our opinion, that’s the name of the game : )

Dr Ivo Waerlop, on of The Gait Guys

Zeitoune GNadal JBatista LAMetsavaht LMoraes APLeporace G.Prediction of mild anatomical leg length discrepancy based on gait kinematics and linear regression model. Gait Posture. 2019 Jan;67:117-121. doi: 10.1016/j.gaitpost.2018.09.027. Epub 2018 Sep 29.

#LLD #leglengthdifference #leglengthinequality #visualgaitanalysis #thegaitguys #gaitanalysis

Where do you do YOUR gait retraining?

It may seem like we are stating the obvious, but visual contrast seems to matter more than visual acuity. When we look at light contrast in lower frequencies (red ranges), we start to see some decomposition of gait with regards to step length, but not necessarily cadence or speed in this study of over 4,000 folks over 50 (hey, that’s us!). What are your patients wearing on their feet? What color is your floor? How about the walls?

Do your gait retraining in a well lit area with lots of contrast between the floor and your patients shoes, as well as the surroundings.


Duggan E, Donoghue O, Kenny RA, Cronin H, Loughman J, Finucane C. Time to Refocus Assessment of Vision in Older Adults? Contrast Sensitivity but Not Visual Acuity Is Associated With Gait in Older Adults. J Gerontol A Biol Sci Med Sci. 2017 Feb 28. doi: 10.1093/gerona/glx021. [Epub ahead of print]


Podcast #31: Walking Straight, Mastalgia & Shoes

podcast link:

iTunes link:

Gait Guys online /download store:

other web based Gait Guys lectures:   type in Dr. Waerlop or Dr. Allen  Biomechanics

Today’s show notes:

1. Neuroscience Piece:

Today we have a neuroscience piece on “turning”, in a matter of speaking. So why, when blindfolded, can’t we walk straight?

These “Turning” field studies appear in Chris McManus’ book, Right Hand, Left Hand, The Origins of Asymmetry in Brains, Bodies, Atoms and Cultures (Phoenix, 2002). 

NPR Story Produced by Jessica Goldstein, Maggie Starbard.

2. neuroscience 2 at the end of the show.
The myth of the 8 hour sleep
3. Blog reader asks:
Any shoe recommendations for an uncompensated forefoot varus?

4. and another from the Blog:
Hi The Gait Guys, what can I do to regain medial tripod? I have a forefoot varus and when I am standing it compensates and my rearfoot everts and gets valgus. I have been having some pain lately and it is annoying me a lot. Please help. Thank you.

5. FACEBOOK readers asks:

Bringing the Foot Back To Life: Restoring the Extensor Hallucis Brevis Muscle.

Foot loading patterns can be changed by deliberately walking with in-toeing or out-toeing gait modifications.

Gait Posture. 2013 Apr 25. pii: S0966-6362(13)00190-2.

7. The Gait Guys are always talking about ankle rocker, dorsiflexion strength and the importance of the anterior compartment of the lower leg. Here is another study to add fuel to our fire.

Ankle dorsiflexor strength relates to the ability to restore balance during a backward support surface translation

Gait & Posture

8. Shoes:

NB new Minimus 10V2

The Minimus 10 is back - and better than ever. The MR10v2 is the latest version of the previous Minimus Road 10,


Study: One-Third of Female Marathoners Report Breast Pain

10. Painkiller meds taken before marathons

from the British Medical Journal

11. The myth of the 8 hour sleep
By Stephanie Hegarty BBC World Service

The funny problem with the stairs at Brooklyn’s 36th Street subway. Why we trip..

  At Brooklyn’s 36th Street subway stop, one of the steps is slightly higher than the others. Stairs have a standardized Rise and Run and when this is altered, specifically the Rise, funny things happen. Filmmaker Dean Peterson set up his camera to capture the stumbles and the video can be seen here and above on our blog.

The dangerous step, it turns out (which has since this video been repaired), is apparently a half-inch higher than the others. Stairway design guidelines vary within a small range.  Guidelines call for risers to be a minimum of 6 inches and a maximum of 7 ¾ inches. The allowable variance between steps is 3/8 of an inch depending on the source you seek.

(The general rule (in the US) is 7-11 (a 7 inch rise and 11 inch run). More exactly, 7 ¾ rise and an 11 ½ inch run, although some people will use a run of as little as 9 inches.)

This is a perfect example of how sensitive and predictive the human body is with all of its amazing joint position sense receptors.  But there is more to it than a simple step height differential. Read on.

There are multiple demands that stairs place on the neuro-musculoskeletal system. There are needs for input from the somatosensory, visual, and vestibular systems at various stages in the task. Some of these collaborating systems deteriorate with the aging process making the failure of stair negotiation a legitimate risk for the elderly or those that are handicapped in one of the 3 primary systems noted above. Studies (see references below) strongly link impairments in the visual system to safe stair  negotiations.  The Buckley study found that the mediolateral balance during stepping up and down stairs (single limb support stability) was significantly reduced (especially stepping down) by blurred vision highlighting the critical necessity of vision in stepping dynamics.  Hence, one must be aware of people traffic on steps, if a stairway is dense with traffic the ability to gain the visual cues of the successive stairs is paramount. The next time you are in a school or subway stairwell notice the undercurrent of your discomfort may be from the inability to see enough steps in front of you.  Letting the person ahead of you clear some distance is a must, especially if you are vision impaired, elderly, wearing dark tinted glasses or are without the ability to use other cues such as railings (ie. adding a tactile feedback system to satisfy the impairment of visual cues). 

There are other user created impairments that we may be unaware of consciously. In the Miyasike-daSilva study it was determined that as participants approached and walked stairs, gaze was within 4 steps ahead of their location indicating that individuals often rely on spatial cues from prior experience or from other visual cues to obtain the necessary information from the environment.  Thus, one must be careful carrying something such as a baby, groceries or laundry basket in front of you thus impairing the lower visual field. We have all carried something up or especially downstairs and either thought we were on the last step or found we had one more to go and found ourselves either stumbling forward or hyperextending our knee as we lurch down onto the unexpected step.  In the video you will see a great example of this forward catch as one of the ladies is carrying a baby in front of her, luckily she makes the correct saving motor choice.  Being able to plan/control landing mechanics are significantly different when the visual system is locked out or impaired from stepping tasks. Timmis found that the contribution of information from the lower visual field of gaze in controlling the landing strategy occurs predominantly prior to or during movement initiation of the foot and limb and that ‘online’ or immediate vision is used only in the latter portion of the descent phase to fine tune the step landing. Buckley found that under visual impairments subjects used the cautious strategy of keeping their weight back on the trail limb longer making weight transfer noncommittal affording the time necessary for the lead limb to fish around for the next step.

There is so much involved in negotiating stairs and steps, even level ground walking. There are many cues we have learned to subconsciously glean information from. Sadly, when we begin to age and lose proprioceptive or visual information things begin to fall apart. The system is so sensitive and intuitive. This is why when someone changes the ground level, or the height of a step as in this video, the system fails even the best of us who have all of our faculties about us. And, we learn more about gravity at that moment than we wish to learn.

Shawn and Ivo, The Gait Guys


1. J Am Geriatr Soc. 2000 May;48(5):567-80. Startzell JK,Owens DA , Mulfinger LMCavanagh PR .Stair negotiation in older people: a review.

2. Gait Posture. 2005 Oct;22(2):146-53.Buckley JG,Heasley K,Scally A,Elliott DB.The effects of blurring vision on medio-lateral balance during stepping up or down to a new level in the elderly.

3. Exp Brain Res. 2009 May;195(2):219-27. Epub 2009 Mar 31.Timmis MA,Bennett SJ,Buckley JG .Visuomotor control of step descent: evidence of specialised role of the lower visual field.

4. Exp Brain Res. 2008 Jan;184(2):223-32. Epub 2007 Aug 29.Buckley JG,MacLellan MJ,Tucker MW,Scally AJ,Bennett SJ.Visual guidance of landing behaviour when stepping down to a new level.

5. Exp Brain Res.2012 Sep 22. [Epub ahead of print]Shinya M,Popescu A,Marchak C,Maraj B,Pearson K.Enhancing memory of stair height by the motor experience of stepping.

6. Exp Brain Res. 2011 Mar;209(1):73-83. Epub 2010 Dec 25.Miyasike-daSilva V,Allard F,McIlroy WE .Where do we look when we walk on stairs? Gaze behaviour on stairs, transitions, and handrails.

7. PLoS One.2012;7(9):e44722. Epub 2012 Sep 6.Does it really matter where you look when walking on stairs? Insights from a dual-task study. V,McIlroy WE.PMID:22970297[PubMed - in process] PMCID:PMC3435292 Free PMC Article