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Re: Live Updates from the Footwear Biomechanics Symposium
We finally got to Tübingen after the 3 harrowing days doing things like queuing up for 90 minutes as the Arena'ettes wanted a photo with Rapunzel @ Paris Disneyland; its a tuff life, but someone has to do it, especially the 8 hr drive and tying to entertain 2x4yr olds!; following the Biomechanics Summer School in Manchester.
Its a big mtg; 250 participants (up from the usual 100 or so of many in the past ISB footwear mtg); 19% from North America and 5% from Australia and NZ (...me, Simon, Chris, Julie, Alex, Karen, Paul, Jason, Kathryn ... )
Daniel Lieberman was first up on Evolution and barefoot running -- I got lost of notes and comments on that and will post later.
160 papers submitted with 42 oral presentations accepted; 50 posters accepted; 8 invited and 2 keynotes (Lieberman today and Nigg tomorrow).
__________________ Craig Payne
__________________________________________________ ___________________________________ Follow me on Twitter | Run Junkie God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The Following User Says Thank You to Craig Payne For This Useful Post:
Re: Live Updates from the Footwear Biomechanics Symposium
Daniel Lieberman – Evolution of the Human Foot and Barefoot Running Here are my notes from his presentation; some of the notes are direct quotes; some are me paraphrasing what he said and my own comments are in italics
“Applying evolutionary theory to feet and shoes”
“Nothing in biology makes sense outside the light of evolution” - quote from Theodosius Dobzhansky
4 key principle of evolutionary medicine:
1. We evolved for very different conditions experienced today (we live lives that our bodies were not meant for)
2. Many symptoms are actually adaptations
3. Null hypothesis: Natural selection is a better engineer than any engineer
4. You, your patients, your clients, subjects etc are not actually normal
“Chimps heel strike” (!!!!!!!)
“No longitudinal arch in chimps”
In last 10-15 yrs, early hominid fossils discovered to give a lot more information on foot evolution
Ardis foot – had cuboid extension that thought t be due to a more rotated position of STJ axis; it was an ape foot that had the characteristics of a biped hominid foot
Knuckle walking (chimps) is a costly inefficient way to walk.
Hypothesis:
Early hominids hunted by running long distances; hunted by chasing prey over long distances to drive the prey into hyperthermia; endurance athleticism explains many of the homo erectus features (he published on this: http://www.fas.harvard.edu/~skeleton/pdfs/2004e.pdf (Pdf file)
Shoes evolved <50 000 years ago; they were minimalist shoes; non-minimalist shoes have only been around for the last 2 generations of human evolution
How shoes changed feet:
1. Foot muscles atrophy
2. Less stable (less proprioception; change lever arms)
3. Change foot strike
Barefoot heel strike hurts
Forefoot striking more compliant (less damping); like jumping and landing on your heel vs ball of the foot
Anecdotal evidence of those who benefit from barefoot running
Anecdotal evidence of those who have been injured from barefoot running
(he was very critical of the barefoot running zealots; kind of interesting given he is such hero to them!)
(he really pushed the lack of data on this topic issue)
How you run is more important than whats on your feet
What is on your feet affects the way you run
There is nothing abnormal about barefoot running – been doing it for millions of years; relentless heel strike is abnormal
Many problems are caused by a mismatch between modern life and the conditions for which we evolved.
Publication under review: rearfoot strikers from a university track team had 2.3x more injuries than the forefoot strikers
Publication under review: 3-4% more economical to run barefoot than in shoes
Barefoot running is:
- Normal
- A useful coach
- Provides info on natural running
If you run with poor form, you are better off in shoes that protect you.
Shoes are fine, but an evolutionary medicine hypothesis is that minimal shoes may have advantages.
__________________ Craig Payne
__________________________________________________ ___________________________________ Follow me on Twitter | Run Junkie God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The Following User Says Thank You to Craig Payne For This Useful Post:
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by Craig Payne
[
Forefoot striking more compliant (less damping);
Compliance and damping are two different things. Compliance relates to leg stiffness or spring constant (K), damping relates to energy lost from the system due to heat and sound etc. I should have thought that there was greater potential for damping in the more compliant running style. The greater the joint excursion, the greater potential for energy loss through friction???? But I should be interested to hear the reasoning here. Studies of running on more compliant surfaces indicate an increase in leg stiffness and lower metabolic cost, suggesting less energy loss when running with stiffer legs. I'll reference if required.
Craig, if you get a chance to talk with him, ask him about this for me.
Re: Live Updates from the Footwear Biomechanics Symposium
If running barefoot is "normal" as Dan Lieberman says, then so is:
1. Not going to the grocery store to buy food but, instead, you must kill animals yourself for food, or go pick fruits and berries from the forest
2. Don't wear clothes...being naked is normal....tell that one to your child's grade school teacher.
3. Don't ride a bicycle, ride in or drive a car, or fly in a airplane or jet. These aren't normal either. You must walk barefoot every you go anywhere since this is normal mode of transportatation. Shoes aren't normal.
4. When you or a loved one gets an infection, you shouldn't take antibiotics, since this isn't normal. Rather you should let nature run its course and let your wife, husband, son or daughter possibly die of the infection since synthetic antibiotics aren't normal.
I'm running out of time, anyone want to continue the list....the native from the village next door who ran over to me naked and with no shoes (i.e. natural), and just shouted at me to get back to hunting and gathering....
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Re: Live Updates from the Footwear Biomechanics Symposium
P.s. How are they measuring damping? I know how to measure leg stiffness, I know how to measure body stiffness, I even have a clue how to measure foot stiffness. But how are they measuring damping? Intrigued.
Re: Live Updates from the Footwear Biomechanics Symposium
Hi Simon ,hope you are well, am i being thick?when you talk of "Stiffness" you mean in a physics definition?In any sport i played you were trying to relax not be tense not to have muscles in high tone, running with stiff legs cant be much fun
Tim
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by timharmey
Hi Simon ,hope you are well, am i being thick?when you talk of "Stiffness" you mean in a physics definition?In any sport i played you were trying to relax not be tense not to have muscles in high tone, running with stiff legs cant be much fun
Tim
Tim, in running the body is modelled as a spring mass oscillator, when we talk of leg stiffness we are talking about the spring constant (K) of the leg within the model. The body modulates this principally through knee and hip flexion and ankle too.
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by Simon Spooner
Compliance and damping are two different things. Compliance relates to leg stiffness or spring constant (K), damping relates to energy lost from the system due to heat and sound etc. I should have thought that there was greater potential for damping in the more compliant running style. The greater the joint excursion, the greater potential for energy loss through friction???? But I should be interested to hear the reasoning here. Studies of running on more compliant surfaces indicate an increase in leg stiffness and lower metabolic cost, suggesting less energy loss when running with stiffer legs. I'll reference if required.
Craig, if you get a chance to talk with him, ask him about this for me.
Will do; surprisingly he made that statement to a room full of biomechanists!
I have lots to report on; but we still have two days to go and the Arena'ettes are also demanding attention.
__________________ Craig Payne
__________________________________________________ ___________________________________ Follow me on Twitter | Run Junkie God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by Simon Spooner
Compliance and damping are two different things. Compliance relates to leg stiffness or spring constant (K), damping relates to energy lost from the system due to heat and sound etc. I should have thought that there was greater potential for damping in the more compliant running style. The greater the joint excursion, the greater potential for energy loss through friction???? But I should be interested to hear the reasoning here. Studies of running on more compliant surfaces indicate an increase in leg stiffness and lower metabolic cost, suggesting less energy loss when running with stiffer legs. I'll reference if required.
Craig, if you get a chance to talk with him, ask him about this for me.
I guess you could argue that the amplitude of the oscillation is lower with stiff legs therefore the oscillation is damped compared to compliant leg running.Or is it that the oscillation is amplified in compliant running?
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by Kevin Kirby
If running barefoot is "normal" as Dan Lieberman says, then so is:
1. Not going to the grocery store to buy food but, instead, you must kill animals yourself for food, or go pick fruits and berries from the forest
2. Don't wear clothes...being naked is normal....tell that one to your child's grade school teacher.
3. Don't ride a bicycle, ride in or drive a car, or fly in a airplane or jet. These aren't normal either. You must walk barefoot every you go anywhere since this is normal mode of transportatation. Shoes aren't normal.
4. When you or a loved one gets an infection, you shouldn't take antibiotics, since this isn't normal. Rather you should let nature run its course and let your wife, husband, son or daughter possibly die of the infection since synthetic antibiotics aren't normal.
I'm running out of time, anyone want to continue the list....the native from the village next door who ran over to me naked and with no shoes (i.e. natural), and just shouted at me to get back to hunting and gathering....
Agreed. The central thesis of Lieberman's hypothesis is that:
Quote:
Originally Posted by Craig Payne
We evolved for very different conditions experienced today (we live lives that our bodies were not meant for)
If any one was to blindly accept that hypothesis, then we would also have to give up everything else that has evolved in the last few generations (ie shoes).
I will reiterate what I said in some other threads many other times, I have nothing against barefoot running/minimalist running; its just the "selective" blind faith put in this hypothesis, albeit, a very interesting hypothesis; I have just taken the time to read this:
Quote:
Originally Posted by Craig Payne
Hypothesis:
Early hominids hunted by running long distances; hunted by chasing prey over long distances to drive the prey into hyperthermia; endurance athleticism explains many of the homo erectus features (he published on this: http://www.fas.harvard.edu/~skeleton/pdfs/2004e.pdf (Pdf file)
I will have to admit, that he has sparked my interest in 'evolutionary medicine' and I have been doing some reading up on it while the Arena'ettes sleep!
__________________ Craig Payne
__________________________________________________ ___________________________________ Follow me on Twitter | Run Junkie God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by Simon Spooner
I guess you could argue that the amplitude of the oscillation is lower with stiff legs therefore the oscillation is damped compared to compliant leg running.Or is it that the oscillation is amplified in compliant running?
The amplitude of the oscillation will be determined in part by the leg stiffness though, so to say it is damped in stiffer legs is a bit of a strange one. Driving me mad this one- ask him please Craig.
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by Simon Spooner
Driving me mad this one- ask him please Craig.
Sorry, I did not see him today; he may have left. We have one more day to go and I have lots to report on. Off now for a boat ride down the Neckar river. See this photo: http://www.flickr.com/photos/27840777@N06/2593838449/
__________________ Craig Payne
__________________________________________________ ___________________________________ Follow me on Twitter | Run Junkie God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by Craig Payne
Sorry, I did not see him today; he may have left. We have one more day to go and I have lots to report on. Off now for a boat ride down the Neckar river. See this photo: http://www.flickr.com/photos/27840777@N06/2593838449/
No worries. Keep those twins away from the sides of the boat!
Question to all and anyone: what determines the natural frequency and the amplitude of oscillation of an undamped spring (harmonic) oscillator?
Re: Live Updates from the Footwear Biomechanics Symposium
Quote:
Originally Posted by timharmey
The frequency is equal to the elasticity of the spring over the mass, and the amplitude depends on the initial displacement
And the initial displacement is dependent upon the load and spring stiffness. So, given that the body modulates the leg stiffness (K) we cannot draw the conclusion that there is less damping in the more compliant leg during forefoot strike running just because the amplitude of the oscillation is greater during forefoot strike running, merely that the leg stiffness is greater during heel strike running. Like I said before, stiffer legs have been shown to be more metabolically efficient, enhance performance and reduce the risk of injury. All yours, Lieberman....
However, we must also be mindful that too stiff probably equals injury in the same way that too compliant probably equals injury. Hence a zone of of optimal leg stiffness (ZOOLS) exists.
Working with a patient at the moment with a history of tibial stress fracture, trying to retrain gait to forefoot strike and minimalist shoes... I'll keep you updated.
Re: Live Updates from the Footwear Biomechanics Symposium
So much more to report on from this conference, will have to get to it over the next few days...
Lower Extremity Segment Co-ordination During Barefoot Running
Alison Gruber, Julia Freedman & Joseph Hamil
Quote:
The reduction in foot eversion with barefoot running was greater than reported values for shod forefoot running. Additionally, increased leg internal rotation with barefoot running is likely due to the alteration in footfall pattern toward the forefoot. Therefore the differences in foot eversion, but not leg internal rotation are due to running unshod and not only due to a change in footfall pattern. Barefoot running did not affect foot-leg co-ordination suggesting barefoot running may not improve or worsen knee stress.
Foot eversion during the stance phase of running is a necessary segmental movement due to the anatomy of the subtalar joint. Maintaining an inverted position throughout stance, like that of barefoot running in the present study, may place increased stress on the inverter muscles and the subtalar joint complex. Additionally, foot eversion provide active shock attenuation during impact. Therefore, barefoot running may remove the shock attenuation provided by foot eversion and cause an increased reliance on other tissues to provide adequate shock attenuation.
__________________ Craig Payne
__________________________________________________ ___________________________________ Follow me on Twitter | Run Junkie God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
Live Updates from the Footwear Biomechanics Symposium
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