Barefoot influence on arch height

Barefoot influence on arch height

 

“Our aims were to establish the prevalence of flat foot in a population of schoolchildren in rural India and to determine whether this prevalence varied between shod and unshod children”

 

First, it is hard to translate this research over to an American population. Just because it is the prevalence in India, doesn’t mean that it will be the prevalence in other countries. Until I have other research though…this is all I have to work with.

 

Unshod means not wearing shoes. Therefore, shod means wearing shoes.

 

“…2300 children between the ages of four and 13…static footprints of both feet were obtained from all 2300 children”

 

This encompasses a large age span from the time prior to arch formation to post arch formation. I remember learning in school that the arch starts to take shape around the age of 8, but this may just be a tradition that has carried through the ages of PT students. Anyway, this is a large sample size to look at.

 

“The footprints were classified as normal, high-arched or flat. Some form of footwear was worn by 1555 children and 745 never used shoes.”

 

It’s still hard to believe that there were this many children that hadn’t used shoes. The children in the study were between the ages of 4 and 13. We sometimes take for granted all of the “needs” that we have here in the states. Anyway, here is a link to give an idea of what the arches would look like on a static footprint. One way to think of it is to get your foot wet and go walk on a wood floor or deck. You would have an imprint of your foot as follows: picture of arch height.

 

“…1551 were considered to have normal arches in both feet, 595 had a high arch in one or both feet and 154 had unilateral or bilateral flat foot. The prevalence of flat foot progressively decreased with increasing age.”

 

This last statement is what is taught in PT school. There are so many facts that are taught in PT school, but we don’t learn the research behind the facts. A majority of children go on to develop normal arch height. There needs to be a further breakdown of the children that go on to develop an “abnormal arch height”.

 

“There was a significantly higher prevalence in children who wore shoes (8.6%) than among the unshod (2.8%)”

 

There is a large difference between the two populations of children, but we also have to consider the small sample size of 154 children. I would love to see this study take it one step further and search for all children in a larger radius with flat feet and see if the same types of prevalence rates are present. If this is the case, then we can start to make some assumptions regarding footwear affecting arch height. There are so many other variables that are not accounted for that could also play a role in arch formation, so this study has to be taken with a grain of salt. It does though make a statement that kids wearing shoes may not develop a normal arch compared to those not wearing shoes. It literally states: “…shoe-wearing predisposes to flat foot”.

 

“It seems that closed-toe shoes inhibit the development of the arch of the foot more than do slippers or sandals. This may because intrinsic muscle activity is necessary to keep slippers from falling off.”

 

This is a good theory, but would have to be proven. As a PT, we tend to recommend against sandal or flip flops because of the same reason: we have to work differently to keep the shoes from falling off. There is something called the windlass mechanism that can be altered when wearing shoes that can easily fall off. Again, more research is needed in order to figure out which party is right.

 

Excerpts taken from:

 

Rao UD, Joseph B. The Influence of Footwear On the Prevalence Of Flat Foot. J Bone Joint Surg [Br]. 1992;74-B:525-527.

 

Link to article

 

 

 

 

Post 83: running mechanics

“Footwear such as sandals or moccasins were invented less than 50,000 yr ago, but the modern running shoe with a cushioned elevated heel, arch supports, and a stiffened midsole was created only in the 1970’s”
 
http://news.nationalgeographic.com/news/2010/06/100609-worlds-oldest-leather-shoe-armenia-science/
 
This is an article that I read a while back talking about the oldest shoe was built about 6,000 years ago. It is not too different from what we know to be a shoe. It covers the foot, has an ability to tighten to the foot and protects the foot from elements on the ground.
 
The standard shoes that we know today were created in the 1970’s. Prior to this, most shoes looked like the typical Keds shoes.
 
“More than 75% of today’s shod runners typically rearfoot strike (RFS, in which the heel first contacts the ground, but barefoot or minimally shod runners more often forefoot strike (FFS), with the ball of the foot landing before the heel, or they sometimes midfoot strike (MFS), with the heel and ball of the foot landing simultaneously”
 
When you run, something has to hit the ground first. This could be the heel, the ball of the foot or both could hit at the same time. This seems like a small point, but what if the type of shoe that you are wearing dictates your running pattern. There’s the old saying that form follows function, but what if the shoes form dictates our function?
 
“…FFS landing, unlike RFS landings, generate no impact peak…Elevated heels also encourage a runner to RFS, even when the foot is slightly plantar flexed, facilitating an longer stride and eliminating controlled dorsiflexion by the plantar flexors during landing”
 
A lot is said here. There is more impact to your body when you heel strike. There is less impact to your body when you forefoot strike. The next jump that is made by some is that an increased impact may lead to increased injury rate. We are not there yet.
 
Also, one loses the ability to control ankle motion when wearing heels. For instance, if you strike the ground with your toes first, the large muscles of the calf control your heel down to the ground. If you strike with your heel first, the smaller muscles on the front of the shin control your toes back to the ground. This is one of the hypotheses behind shin splints, in that the repeated lowering the toes to the ground causes the muscle to be overworked.
 
“…runners switched from an RFS gait in shoes to an MFS or FFS gait when barefoot or minimally shod”
This may be the smoking gun. When you wear standard shoes, you are more likely to strike your heel on the ground first and when you run barefoot, you are more likely to strike the ball of your foot. This is the concept behind people wearing the toe shoes for running (see vibram 5 fingers), as there is less impact on the body when wearing a minimalist shoe.
 
“At a given speed, the cost of transport during running increases approximately 1% for every 100g of added shoe mass”
 
This makes sense right? If the shoes are heavier, then it will require more energy in order to move your foot. This is another reason for lighter shoes during distance running. The lighter shoe will have less padding though. This will cause a change in the runner’s stride patterns. So far a lighter/minimalist shoe takes less energy to run and reduces impact on the body. Not seeing the negatives yet…they exist and will be covered at a later post.
 
“Although higher external dorsiflexion moments in FFS gaits cause higher triceps surae contractile costs, more controlled dorsiflexion during an FFS could perfmit more elastic energy storage and return because the heel descends substantially under controlled dorsiflexion, stretching the Achilles tendon while the triceps surae contracts eccentrically or isometrically”
 
First, the authors are from Harvard. This should explain all of the smartsy language used above. What this means is that when a person lands on the ball of the foot, the calf muscle has to take more of the work than the muscles on the front of the shin. When this happens, this could lead to a problem such as Achilles tendonitis. Also, by loading up the Achilles there could be more energy output from the stretching of the Achilles during the running cycle. Think of a spring. When you pull the spring apart, and then let go…what happens? Assuming you didn’t deform the spring, it bounced right back to its shortened position. Well, assuming your don’t tear the Achilles, it will bounce back to its shortened position, which when running will help to propel the runner forward (depending on the amount of forward lean of course, but this is a topic for another post or discussion).
 
“Another biomechanical difference between FFS an RFS running is knee flexion. RFS runners typically land with the foot in front of the knee, which is more extended and less complaint at strike but then flexes more during stance; in contrast, FFS runners land with an initially more flexed knee and have more knee flexion during impact but flex the knee less thereafter”.
 
I recommend watching videos by Brian Mackenzie or google Dr. Nicholas Romanov to learn more about the FFS style of running. In essence, when you land with a straight knee and a heel strike, you are effectively placing a braking force on your running, meaning that it is slowing you down slightly and you have to overcome the breaking force in order to propel yourself forward again. When you land with a flexed knee and the foot underneath you or better yet, slightly behind you, you are allowing for a propelling force instead of a breaking force. Also, landing on a less compliant knee is no good. If you jump and land on a locked out knee compared to landing on a slightly bent knee, which one will feel better? Please…go try it and come back.
 
“…running in minimal shoes is slightly less costly (on average, 2.41%-3.32%) than running in standard shoes after accounting for the effects of shoe mass, strike type, habitual footwear, and stride frequency.”
 
Essentially running in a minimalist shoe, which in this study was the Vibram 5 Fingers, requires less energy to run the same distance compared to wearing a standard shoe. Although this number seems small, over a long duration race or better yet, over the course of a running career, this could have a great impact.
 
This is a smaller study, so the results will need to be replicated in a larger group, but it is one of the first studies to directly assess the difference between running in a minimalist shoe compared to a standard shoe.
 
Excerpts taken from:
 
Perl DP, Daoud AI, Lieberman DE. Effects of Footwear and Strike Type on Running Economy. Med. Sci. Sports Exerc.2012;44(7):1335-1343.
 
 

Do you run loudly?

Shhhhhh…quiet. Tread lightly and land softly. May your joints forever feel young.

  1. “Several of these programs instruct participants to land softly in an attempt to teach proper landing technique and reduce impact forces. Mandelbaum et al reported an 88% decrease in anterior cruciate ligament injuries in 1041 female subjects using soft landing cues”

Are you thinking what I’m thinking? Seinfeld? Mandelbaum seriously?! This was the family of old guys in the hospital with Jerry that kept hurting themselves trying to lift the t.v. I thought it was funny.

What the above is saying is that the sound of your landing can directly indicate your injury risk. Don’t go jumping off buildings to test this theory! I won’t be held liable.

 

  1. “13% decrease in peak vGRF during a drop-landing task when 80 adult recreational athletes were instructed to listen to the sound of their landing…reduced by 24% in a stud in which 12 female recreational athletes were asked to land softly…”

What this means is that the softer you land the quieter you land. vGRF is vertical Ground Force Reaction (some people really hate it when I mix up the letters, but oh well…You know who you are!). This is it this way. For every action, there is an equal and opposite reactions. This means that if you land with a heavy load, the ground pushes back up at you with an equal load. If you absorb some of the load with your joints by bending, then the ground doesn’t push back as hard. Think of dropping a stick vertically from a specific height. The stick will actually bounce a little after it hits the ground, because the ground pushes back. Now do the same experiment with a wet noodle and you will get a totally different result. This may not be an exact science, but at least it makes sense to me. When you land quietly (wet noodle), you don’t get the jarring force from the ground as when you land loudly.

  1. “Initially, the participants were instructed to perform drop landings (with no instruction) to obtain a baseline, normal sound amplitude of landing…then instructed to …create a quieter or louder sound from this normal landing condition”

For those of you that perform high-intensity exercise of varying modes under time domains-based exercises, (I am unsure that if I use the word crossfit that I may be sued like those before me) such as box jumps, that this study will apply to you.

  1. “quiet-landing instruction results in significantly greater joint excursion at the ankle and knee when compared to a normal landing sound instruction”

Essentially, the quieter that you try to land, the more that you perform a squatting based movement on the land. The stiffer you land, the louder you are. The louder you are, the more force (think jarring) that your joints have to endure.

MORAL: Be quiet! Tread lightly!

Excerpts taken from: Wernli K, NG L, Phan X, et al. The Relationship Between Landing Sound, Vertical Ground REaction Force, and Kinematics of the Lower Limb During Drop Landings in Healthy Men. J Orthop Sports Phys Ther. 2016;46(3):1945-199.

If you would like a running assessment or are experiencing pain during running, come see me at:

Functional Therapy and Rehabilitation

(Now part of the Goodlife family)

903 N 129th Infantry Dr

Joliet IL

8154832440