More on the scourge of Flip Flops. Riding the inside edge of the sandal. Mystery hunting with Dr. Allen.

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Tis the season upon us. Riding the inside edge of the sandal.
You can see it in the photo, the heel is a third of the way off the sandal.

You either have it or have seen it. It is frustrating as hell if you have it. Your heel rides on only half of your flip flop or summer sandals. You do not notice it in shoes, only in sandals, typically ones without a back or back strap. This is because the heel has no controlling factors to keep it confined on the rear of the sandal sole. There is no heel counter on open backed shoes and sandals, the counter keeps the heel central on the back of the footwear. There is a reason this inside edge riding happens to some, but not everyone. It is best you read on, this isn’t as simple as it might seem.

These clients may have restricted ankle rocker (dorsiflexion), restricted hip extension and/or adductor twist (if your reference is the direction the heel is moving towards). I could even make a biomechanical case that a hallux limitus could result in the same scenario. So what happens is that as the heel lifts and adducts it does not rise directly vertically off the sandal, it spins off medially from the “adductor twist” event. This event is largely from a torque effect on the limb from the impaired sagittal mechanics as described above, manifesting at the moment of premature heel rise resulting in an slightly externally rotating limb (adducting heel). The sandal eventually departs the ground after the heel has risen, but the sandal will rise posturing slightly more laterally ( you can clearly see this on the swing leg foot in the air, the sandal remains laterally postured). Thus, on the very next step, the sandal is not entirely reoriented with its rear foot under the heel, and the event repeats itself. The sandal is slightly more lateral at the rear foot, but to the wearer, we believe it is our heel that is more medial because that is the way it appears on the rear of the sandal or flip flop. Optical illusion, kind of… . . a resultant biomechanical illusion is more like it.

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You will also see this one all over the map during the winter months in teenagers who swear by their Uggs and other similar footwear, as you can see in the 2nd photo above. This is not an Ugg or flip flop problem though, this is often a biomechanical foot challenge that is not met by a supportive heel counter and may be a product of excessive rear foot eversion as well. This does not translate to a “stable” enough shoe or boot, that is not what this is about. This is about a rearfoot that moves to its biomechanical happy place as a result of poor or unclean limb and foot biomechanics and because the foot wear does not have a firm stable and controlling heel counter. This is not about too much pronation, so do not make that mistake. And orthotic is not the answer. A heel counter is the answer. The heel counter has several functions, it grabs the heel during heel rise so that the shoe goes with the foot, it give the everting rearfoot/heel something to press against, and as we have suggested today, it helps to keep the rearfoot centered over the shoe platform. To be clear however, the necessary overuse and gripping of the long toe flexors to keep flip flops and backless sandals on our feet during the late stance and swing phases of gait, clearly magnifies these biomechanical aberrations that bring on the “half heel on, half heel off” syndrome.

There you have it. Another solution to a mystery in life that plagues millions of folks.

Shawn Allen, the other gait guy

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Riding the inside edge of the sandal. Mystery hunting with Dr. Allen.

You can see it in the photo above, the heel is a third of the way off the sandal. (there are 2 photos provided today, find the arrow and tab to see both)

You either have it or have seen it. It is frustrating as hell if you have it. Your heel rides on only half of your flip flop or summer sandals. You do not notice it in shoes, only in sandals, typically ones without a back or back strap.  This is because the heel has no controlling factors to keep it confined on the rear of the  sandal sole. But there is a reason this happens to some, but not everyone. It is best you read on, this isn’t as simple as it might seem. 

These clients have restricted ankle rocker (dorsiflexion), restricted hip extension and/or adductor twist (if your reference is the direction the heel is moving towards). I could even make a biomechanical case that a hallux limitus could result in the same scenario. So what happens is that as the heel lifts and adducts it does not rise directly vertically off the sandal, it spins off medially from the “adductor twist” event. This event is largely from a torque effect on the limb from the impaired sagittal mechanics as described above, manifesting  at the moment of premature heel rise resulting in an slightly externally rotating limb (adducting heel). The sandal eventually departs the ground after the heel has risen, but the sandal will rise posturing slightly more laterally ( you can clearly see this on the swing leg foot in the air, the sandal remains laterally postured). Thus, on the very next step, the sandal is not entirely reoriented with its rear foot under the heel, and the event repeats itself. The sandal is slightly more lateral at the rear foot, but to the wearer, we believe it is our heel that is more medial because that is the way it appears on the rear of the sandal or flip flop.  Optical illusion, kind of… . . a resultant biomechanical illusion is more like it.

You will also see this one all over the map during the winter months in teenagers who swear by their Uggs and other similar footwear, as you can see in the 2nd photo above. This is not an Ugg or flip flop problem though, this is often a biomechanical foot challenge that is not met by a supportive heel counter and may be a product of excessive rear foot eversion as well.  This does not translate to a “stable” enough shoe or boot, that is not what this is about. This is about a rearfoot that moves to its biomechanical happy place as a result of poor or unclean limb and foot biomechanics and because the foot wear does not have a firm stable and controlling heel counter.  The heel counter has several functions, it grabs the heel during heel rise so that the shoe goes with the foot, it give the everting rearfoot/heel something to press against, and as we have suggested today, it helps to keep the rearfoot centered over the shoe platform.  To be clear however, the necessary overuse and gripping of the long toe flexors to keep flip flops and backless sandals on our feet during the late stance and swing phases of gait, clearly magnifies these biomechanical aberrations that bring on the “half heel on, half heel off” syndrome.

There you have it. Another solution to a mystery in life that plagues millions of folks. 

Dr. Shawn Allen, mystery hunter, and one of the gait guys.

If you work in a shoe store, you better understand the real problem behind this frequent shoe breakdown. You have seen it, but do you truly understand it ?  
    Stripping of the heel counter: a naughty problem. (note the foam break down at the inside heel of the shoe in this photo of an almost new pair of shoes)    
 Has the inside of the heel counter of your shoe ever looked like this? 
 Do you know why ? We will tell you why !   * #4 is the lightbulb moment for most people,.   
 1. you may be lazy and not tie your shoes and try to slip  your foot into/out of your shoe without unlacing and re-lacing. This will often fold the top of the counter over upon its self and start some breakdown. Kids are lazy, but so are some adults. 
 2. your laces may be laced to loosely and your heel is excessively slipping/riding up and down on the heel counter foam/material.   
 3.  you have a nasty Halglunds deformity that is just so big it is creating too much friction. 
 4. However, there is often a better and more logical reason and it just so happens that it is the one that no one thinks of or understands.   Loss of ankle rocker (AKA loss of ankle dorsiflexion.   You see, the heel counters job is to gently create counter pressure against the back of the heel/calcaneus so that when the person moves into terminal stance phase of gait (when the heel begins to rise) the heel rise will pull the heel of the shoe up AT THE SAME TIME !  If there is a differential in this time stamp event, then the heel will rise abruptly against a shoe that has not had time to finish forefoot rockering at toe-off through the normal forefoot siping on the outsole.  In other words, if ankle rocker/dorsiflexion is less than sufficient the restricted range will necessitate that the  heel rise BEFORE it is technically supposed to do so, AND thus, before the shoe will reach its build in rocker that enables the heel rise. The two events  have to occur at the same time ! When a person has impaired ankle rocker and thus goes into premature heel rise, the shoe will essentially still be attempting to get to the forefoot rocker built into the shoe (which will lift the heel of the shoe passively). So, if the heel rise is premature, before the shoe gets to the forefoot rocker, the heel will abruptly, yet subtly, slide up the heel counter and shear the foam on the inside of the heel counter. Keep in  mind that once the heel slide and the shoe heel counter engage together the shoe will be suddenly thrust into its (the shoe’s) forefoot rocker. But, you should understand that this is premature forefoot loading response, and it has a host of clinical problems that go along with it (ie. metatarsal stress fractures, premature or excessive forefoot pronation, toe clenching etc).  
   * clinical pearl: this problem often presents with the runner having dorsal foot pain across the top of the foot. The runner will naturally think it is the tightly tied shoes, so the natural solution is to lace the shoes looser and looser (or skip lace) until the point they no longer stay on the foot because of the heel counter sliding. Neither one fixes the dorsal foot pain, because the lacing is not the issue. The astute shoe fitter will realize that this dorsal foot pain is directly related to the loss of ankle rocker, but that is a blog post for another time.    
 It is natural for runners to try to tie their shoes tighter to stop the feeling of the heel slip but this is not the solution.  Ankle strangling is not the solution. 
 Either the shoe is: 
 1. not fit properly matching the person’s natural forefoot rocker phase to the shoe’s natural rocker or 
 2. they have a narrow heel (and thus also need a more appropriately fit shoe) 
 3. need to learn to lace the shoes properly (this does not mean strangle the ankle, any shoe that needs to be tied that tightly to prevent this phenomenon is not the correctly fitted shoe).  Shoe tie tension should be modest, comfortable and not constrictive…… ie hardly noticeable. 
 OR:   
 the person needs more ankle rocker !  Which does not necessarily mean more calf stretching. It means EARNING posterior length through anterior strength. Watch one of our  solution exercises here   .  Earn the changes you need, no one wants to have to performs stretches before every run for the rest of their lives.  Who has that kinda time ?!  
 Better yet, why not take our National Shoe Fit Certification Program and learn the truths about shoe fit and clean biomechanics.  Or, you can leave the pathology alone and support your friendly neighborhood shoe store and local running injury guru more frequently than usual or than is necessary.  Its your money and your time. 
 Links to the National Shoe Fit certification program: 
  Gait Guys online /download store (National Shoe Fit Certification and more !) :  
  http://store.payloadz.com/results/results.aspx?m=80204  
  other web based Gait Guys lectures:  

  www.onlinece.com     type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”  

  Shawn and Ivo, The gait guys  
 Sharing the secrets of gait and walking/running biomechanics that you are not taught elsewhere.

If you work in a shoe store, you better understand the real problem behind this frequent shoe breakdown. You have seen it, but do you truly understand it ?

Stripping of the heel counter: a naughty problem. (note the foam break down at the inside heel of the shoe in this photo of an almost new pair of shoes)

Has the inside of the heel counter of your shoe ever looked like this?

Do you know why ? We will tell you why !  * #4 is the lightbulb moment for most people,. 

1. you may be lazy and not tie your shoes and try to slip  your foot into/out of your shoe without unlacing and re-lacing. This will often fold the top of the counter over upon its self and start some breakdown. Kids are lazy, but so are some adults.

2. your laces may be laced to loosely and your heel is excessively slipping/riding up and down on the heel counter foam/material.  

3.  you have a nasty Halglunds deformity that is just so big it is creating too much friction.

4. However, there is often a better and more logical reason and it just so happens that it is the one that no one thinks of or understands.  Loss of ankle rocker (AKA loss of ankle dorsiflexion.  You see, the heel counters job is to gently create counter pressure against the back of the heel/calcaneus so that when the person moves into terminal stance phase of gait (when the heel begins to rise) the heel rise will pull the heel of the shoe up AT THE SAME TIME !  If there is a differential in this time stamp event, then the heel will rise abruptly against a shoe that has not had time to finish forefoot rockering at toe-off through the normal forefoot siping on the outsole.  In other words, if ankle rocker/dorsiflexion is less than sufficient the restricted range will necessitate that the  heel rise BEFORE it is technically supposed to do so, AND thus, before the shoe will reach its build in rocker that enables the heel rise. The two events  have to occur at the same time ! When a person has impaired ankle rocker and thus goes into premature heel rise, the shoe will essentially still be attempting to get to the forefoot rocker built into the shoe (which will lift the heel of the shoe passively). So, if the heel rise is premature, before the shoe gets to the forefoot rocker, the heel will abruptly, yet subtly, slide up the heel counter and shear the foam on the inside of the heel counter. Keep in  mind that once the heel slide and the shoe heel counter engage together the shoe will be suddenly thrust into its (the shoe’s) forefoot rocker. But, you should understand that this is premature forefoot loading response, and it has a host of clinical problems that go along with it (ie. metatarsal stress fractures, premature or excessive forefoot pronation, toe clenching etc). 

* clinical pearl: this problem often presents with the runner having dorsal foot pain across the top of the foot. The runner will naturally think it is the tightly tied shoes, so the natural solution is to lace the shoes looser and looser (or skip lace) until the point they no longer stay on the foot because of the heel counter sliding. Neither one fixes the dorsal foot pain, because the lacing is not the issue. The astute shoe fitter will realize that this dorsal foot pain is directly related to the loss of ankle rocker, but that is a blog post for another time. 

It is natural for runners to try to tie their shoes tighter to stop the feeling of the heel slip but this is not the solution.  Ankle strangling is not the solution.

Either the shoe is:

1. not fit properly matching the person’s natural forefoot rocker phase to the shoe’s natural rocker or

2. they have a narrow heel (and thus also need a more appropriately fit shoe)

3. need to learn to lace the shoes properly (this does not mean strangle the ankle, any shoe that needs to be tied that tightly to prevent this phenomenon is not the correctly fitted shoe).  Shoe tie tension should be modest, comfortable and not constrictive…… ie hardly noticeable.

OR:  

the person needs more ankle rocker !  Which does not necessarily mean more calf stretching. It means EARNING posterior length through anterior strength. Watch one of our solution exercises here  .  Earn the changes you need, no one wants to have to performs stretches before every run for the rest of their lives.  Who has that kinda time ?! 

Better yet, why not take our National Shoe Fit Certification Program and learn the truths about shoe fit and clean biomechanics.  Or, you can leave the pathology alone and support your friendly neighborhood shoe store and local running injury guru more frequently than usual or than is necessary.  Its your money and your time.

Links to the National Shoe Fit certification program:

Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”

Shawn and Ivo, The gait guys

Sharing the secrets of gait and walking/running biomechanics that you are not taught elsewhere.

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Retail Focus Thursday: The Heel Counter/ Heel box

Let’s differentiate between the heel counter and a lateral flare of the out sole.

The heel counter refers to the back part of the upper of a shoe that actually holds the heel in place (see left above).

The lateral flare is part of the outsole, where it is enlarged laterally, to create stability to a shoe. (see right above). It does this at the expense of speeding up pronation (we usually strike on the outside of the heel, creating a greater sidtance to travel in the same amount of time; again, another post for another time). Good idea for one problem, but often creates another.

The heel counter is necessary, because as the foot pronates from its initial contact with the ground through midstance, the calcaneus moves laterally (or as shoe pro’s say “it everts”).  If the calcaneus does not encounter something to abut up against (like the heel counter), to stop rearfoot pronation at the appropriate time, it will continue to evert and the medial arch will collapse.

“So what” you say? Excessive rearfoot motion, like this can not only cause prolonged midfoot pronation (remember it pronates to absorb shock to midstance, then supinates to create a rigid lever to push off of. Click here if you need a pronation review), but is a common cause of heel blisters. How many times do you remove a clients shoe (hopefully you are removing their shoes and looking at their feet before selling them some shoes) and you notice a “bump” (and sometimes a blister) on the back of the heel (see above) and the outer portion of the heel box is worn on the inside of the shoe? Hmm, sounds like too much room in the heel box.

What causes too much room in a heel box? Narrow heels (or calcaneii , as we like to say) or literally, too much room. The “too much room” scenario often happens when you put a woman’s heel (usually narrow) in a men’s shoe (often wide)

A little lost? Have no fear;  the complete shoe fit program (with IFGEC certification if desired) is coming in the next few months. Watch here, on Facebook or Twitter for the announcement.

The Gait Guys…Shoe afficianado’s. Bringing you the facts so you can make better decisions….

heel counter image from: www.hughston.com

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Shoe Anatomy 101:

If you are truly to be a shoe geek, then you must be familiar with some “shoe anatomy.” Simply put, there is the sole ( the part that contacts the ground), the midsole (the part right between the sole and the last), the shank (the stiff rear part of the midsole), the last (the part on top of the midsole and where the insert or orthotic will sit), the insole (the removable insert), the upper (the part above the last that has the sides, laces, etc)the heel counter (the part that holds the heel in place), and the toe box.

Lets discuss each in turn

 

The Sole (also called the outsole)

This is the part of the shoe that comes in contact with the ground. It is usually made of rubber and provides for some degree of shock absorption and traction. For running shoes, it is usually cemented to the midsole.

Remember that the heel strikes the ground at approximately a 16° angle lateral from the center of the heel  (in a heel strike gait, no we aren’t condoning this, this is how shoes are designed).  The force is then transmitted from the sole of the shoe, up the lateral column of the foot and across to the first metatarsal for propulsion.  This can be assisted by a “rocker” which is a “drop” put into the front portion of some stiffer trail shoes, to ease walking and assist in toe off.  (This is good for people with Morton’s toes or hallux rigidus).

A flare to the sole of the shoe, particularly lateral can be important for stability on uneven surfaces.  A lateral flare provides extra stability upon heel strike, but it speeds up the rate of pronation.  This may be a bad thing, depending on your feet. This flare must extend the length of the sole, otherwise injury can occur at the mid tarsal joint as the foot comes through mid stance. A medial flare can help to prevent overpronation, as the foot comes through mid stance. Again, it must run the length of the shoe.

Look at the lugs on the sole. Are they beveled or straight? A straight lug or cleat will hold on to mud, whereas a beveled one will shed it. This is an important consideration if running off road. How about the cleat pattern (front vs. back and side to side)? Are they symmetrical or opposing? Opposing patterns will enable you to ascend and descend easier at the expense of a slight amount of speed.

The Midsole (sandwiched between the sole and upper)

Midsole material is very important, as it will accommodate to the load imposed on it from the person and their body weight. It serves as the intermediary for load transfer between the ground and the person.  Softer density material in the heel of the shoe softens the forces acting at heel strike and is good for impact and shock absorption. The stiffer the material, the more motion control.  Air is an excellent shock absorber, however it does not deform, it displaces. This creates and unstable surface for the foot, promoting ankle injuries. Foam and gel are much better as they transduce the force and dissipate it. Often midsoles are made with something called “dual density”.  This means that the midsole is softer on its lateral aspect, to absorb force and decrease the velocity of pronation during heel strike and midstance, with a firmer material medially that protects against overpronation as you come through mid stance and go through toe off.

The Shank (this can be within the midsole)

The shank is the stiff area of the shoe between the heel to the transverse tarsal joint. It corresponds to the medial longitudinal arch of the foot, provides torsional rigidity to this shoe and helps to limit the amount of pronation and motion at the subtalar and mid tarsal joints.

The Last (the part between the midsole and insole)

The last (look inside the shoe on top of the shank) is the surface that the insole of the shoe lays on, where the sole and upper are attached).    Shoes are board lasted, slip lasted or combination lasted. A board lasted shoe is very stiff and has a piece of cardboard or fiber overlying the shank and sole (sometimes the shank is incorporated into the midsole or last) .  It is very effective for motion control (pronation) but can be uncomfortable for somebody who does not have this problem.  A slip lasted shoe is made like a slipper and is sewn up the middle.  It allows great amounts of flexibility, which is better for people with more rigid feet.  A combination lasted shoe has a board lasted heel and slip lasted front portion, giving you the best of both worlds.

When evaluating a shoe, you want to look at the shape of the last (or sole).   Bisecting the heel and drawing an imaginary line along the sole of the shoe determines the last shape.  This line should pass between the second and third metatarsal.  Drawing this imaginary line, you are looking for equal amounts of shoe to be on either side of this line. Shoes have either a straight or curved last.  The original idea of a curved last (banana shaped shoe) was to help with pronation.  A curved last puts more motion into the foot and may force the foot through mechanics that is not accustomed to. Most people should have a straight last shoe. 

The Upper (the sides and top of the shoe)

This is the part above the midsole that holds your foot on the sole. It is usually made of nylon, Gore-Tex or some other man made material. Pick something light and breathable.

The Heel Counter (the back of the upper)

This is part of the upper. A strong, deep heel counter with medial and lateral support is also important for motion control; lateral support especially for people who invert a great deal or when you’re going to place an orthotic in the shoe which inverts the foot a great deal.  The lateral counter provides the foot something to give resistance against.  This needs to extend at least to the base of the fifth metatarsal, otherwise it can affect the foot during propulsion. A deep heel pocket helps to limit the motion of the calcaneus and will also allow space for an orthotic. The heel counter should grip right above the calcaneus, hugging the Achilles tendon.

The Toe Box

The toe box should be generous enough to prevent crowding and pressure on the metatarsal heads.  The widest portion of the shoe should parallel a line bisecting the metatarsal heads.  Excessive pressure can result in bunions and/or hammertoes.  The shoe may soften and break down laterally, but it will not increase in length.

When measuring feet and determining shoe sizes, do it both sitting and standing, because the laxity of ligaments can become very evident, especially when the foot is weight bearing or you have the weight of a pack on your back.  If the person has greater than one size of splaying in both length and width when going from one position to the other, go for the bigger size.  Always use ball length rather than sole length. People usually buy smaller shoes because when you pronate, there is less volume in the mid foot and a smaller size shoe will feel better.

The Insole (the removable inner footbed)

This is the part of the shoe that most people remove to put in an orthotic. They have come a long way in construction and make a big difference in shoe fit. They are usually made of some type of foam or EVA material. Some of the newer ones are even dual density foam.

Well, if you made it through this, you are officially as nerdy as us. We’ll see you in the shoe isle…..

 We remain, The Gait guys….