All, I spent a pleasant afternoon with a colleague recently where we looked at in-shoe pressure measures. I heard terms like "early heel lift", "normal pressure distribution" etc. I bit my tongue for the sake of the meeting. So, let's go back to first principles- who says when the heel should lift off the ground in a given individual? Why shouldn't this timing be variable between individuals given that if the time of heel lift should be seen as a phenotype (P) and that P= Genotype + Environment + (Genotype x Environment)? Moreover, that any difference in such timing can just be seen as variation and not something that needs to be "controlled" nor "corrected"?... Can't believe that in this day and age, we should believe in some sort of artificial dichotomy which allows us to label an individuals pressure analyses as "normal" versus "abnormal" is it just me?
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The whole concept of the "normative database" I just don't get... can someone please explain to me why comparing an individual to the mean of lots of individuals is a valid approach.... I just don't get it.. given that P= G + E + (Gx E)...?
Your thoughts... because I'm honestly thinking of taking up a job in a supermarket that doesn't require for me to even think about this kind of bull**** any more.
So, starter for ten: who says when exactly the heel should lift during walking gait, and why should it lift at this time... let's hunt down the references and see what we are left with other than conjecture.... nothing.
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Lower limb alignment characteristics are not associated with running injuries in runners
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We can look at the high blood pressure model. Strokes....
So, taking the tissue stress approach to the time of heel off in gait. Those with an early heel off will be spending more time on their forefoot and with greater length of time with a greater bending moment on the midfoot. Agreed there is no research now, but it could easily become someones project with multiple parts. Is timing of heel off consistent over time? Is there a correlation with early heel off (1 or 2 standard deviations from the mean time of heel off?) with metatarsalgia?, with arch strain? Does a heel lift actually change the force time integral for the forefoot. It's plausible.
Tissue stress and STJ axis position. We need work here too. Can raters consistently sort axis position into groups of medial, avg. and lateral? Does a medial heel skive prevent pathology in feet with medially deviated STJ axes? etc.
Both of those are plausible, but we haven't done the studies. So, I think we can have some measures, eventually, that we can compare to. However, those measures should have a plausible biologic explanation of why they are useful. Sub talar joint neutral and vertical heels don't really have an explanation of why there should be any correlation with pathology.
Eric -
Then we may have someone spending more time on their forefoot, but with stiffer metatarsals... -
Daniel -
when you are in the supermarket a blind woman asks you to pick her out an apple you say what size big? small? she says normal
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To me the first thing to do would be to partition the variance in "time of heel lift"... So list all of the factors which might interact to determine when the heel lifts....
Thinking about it, you might need to first define why the heel lifts at all during gait? -
FWIW I have been having the similar issues my head hurts too much these days :bang: patients getting so much bs information -
I swore to myself that I would not get involved in this stuff again - too many slaggings from the nonsense department; The key words here are normal-atypical-abnormal. Where do the boundaries lie - well that is up to science, underpinned of course by clinical evaluations (which in itself is science). I guess one should be reminded of standard deviations each side of the norm, but then, those in the know, already have this information. If it was down to me, I would start at Cochran and work out.
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So, lets say we have a clinical method of measuring STJ axial position and a normative data set for STJ axial position the mean of which is 42:16, but no-one in that data set actually has that STJ axis position. We examine an individual and find that their STJ axial position is deviated markedly from this mean, should we be attempting to make this STJ axial position more like the mean? -
Hope your lectures at Biomechanics Summer School went well for you and all those involved. Looking forward to being there again next year.
In my opinion, the term "normal" has been "ruined" for generations of podiatrists by Merton Root and colleagues by using the term "normal" to mean "ideal". This seems to be unique to podiatry but not to other health professions which seem to have no problems using the term normal to mean a range of values seen within the human population to describe structure, function, lab values, x-ray values, etc.
I wrote a Precision Intricast newsletter on this very subject in September 2015, here it is, reprinted with permission:
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Eric -
Eric -
Ankle joint dorsiflexion stiffness, midfoot dorsiflexion stiffness, digital dorsiflexion stiffness... Foot length? Age? Gender? Walking velocity? etc. etc. -
We were taught in school that you assessed early heel off by where the swing leg was when heel off of the stance leg occurred. I still like this as it gives some indication of where the center of mass of the body is, in relation to the stance foot, when the heel lifts.
One of my goals in thinking about this is to have some objective data on when to add a heel lift to the orthotic or the the shoe. An aside We would still have to see if a heel being helpful is even related to the timing of heel off in gait.
Again thinking out loud,
Eric -
For this reason, I like Tim Harmey's throw away comment regarding the "normal" sized apple. Even if we take "normal" to mean the arithmetic mean, the mean size of apple will vary across the differing varieties of apple- they're all apples, but in order to know whether the apple we have before us is "normal" in size, we need more details- specifically in this example the variety of apple. If we compared our Cox apple to a database that includes large cooking apples such as the Bramley, it may appear smaller than average (normal) when in reality it is above average size for a Cox. Do we see racial variation in the timing of heel lift?
What if we compared an apple which has one month growth with apples that have been growing for 3 months...?
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Thanks,
Daniel -
What I was tring to get to that we are always looking for the "normal" as a point of referrence.I train boxers some kid showns up does a bit of moving around the other trainer asks what do you think of him, I think through my memeory bank and think is he good /bad/ execeptional .We are always looking for a point of reference when we describe anything. Glad I was making some useful contribution rather than just being a pain in the arse , or my normal self
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So, there are reasons we need to subdivide the data in plantar pressure measures, just as there is a reason we subdivide by weight in boxing... -
If the heel lifts off of the ground when the center of mass is directly above the foot, either the center of mass will be lifted, putting more strain on the arch, or there will have to be flexion of the hip and knee that will prevent raising of the center of mass. The increased flexion of the knee and hip could put more strain on both of those structures.
When the heel lifts when the center of mass is in front of the stance leg, the body will not necessarily have to be raised vertically. Also, the heel can lift without ankle plantar flexion as the body pivots, in the sagittal plane, over the metatarsal heads. So, there can be less arch strain than if the center of mass is lifted.
Eric -
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Have you ever seen the film Money ball some geek works out the best baseball players to buy based on stats and works magic( a true story)
I know nothing about basball but the stats were performance based , ( most bases stolen!?!), maybe we need away of linking things like heel lift to functional outcome measures -
Daniel
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Lower limb alignment characteristics are not associated with running injuries in runners
|
New Balance to launch 3D printed running shoes
>
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