So the online discussion following the UKSEM 'Barefoot Running' Roundtable continues.
Here is a sample of the responses to Ross Tucker's blog after his hosting of the debate (see yesterday's SPACE Blog for details on blogs from some of the protagonists Barefoot Running Blogs ) & a video clip demonstrating barefoot and minimalist-shod runners at the NYC Barefoot Run.
Filmed at 300 frames per second, note on the video the variation in foot strike patterns demonstrating that there are not necessarily consistent styles of running when exercising barefoot or with shoes.
Simon Bartold has commented on the Ross Tucker Blog:
Hi Ross.. nice precis of the debate. If I might just make a few comments that I think may have been missed. The first is that it was not ASICS that were concerned so much about hostilities, although of course they knew this had to be managed, but rather the conference management, and in particular Lieberman. I was actually told 12 hours before the debate that he had insisted on including a 6th speaker, his friend and barefoot coach Lee Saxby, because he was concerned the barefoot argument had been highjacked by ASICS. Given the composition of the panel and your own presence, this seemed highly inappropriate, and smacked of insecurities of his own "theories". If you are going to work in the kitchen, at some point one has to take the heat.
You made the comment " But it led to an argument, because I think Simon Berthold misunderstood the point of the analogy. He had printed off Lieberman's website explaining barefoot running and adamantly criticised Lieberman's explanation. "
I think that is a pity, because I understand the analogy exactly. The point I was making is that Lieberman says in his webpage that the" foot and leg come to a dead stop". It is there for all to read. Sorry, at heal strike the foot and leg do not come to a dead stop, and the problem I have with this is that people read his site and naturally assume that if he says it it is gospel, (a little like the Nature article, but that is another debate). What he says is taking a rigid model of the foot and leg and failing to understand he is applying it to a dynamic system. At the very worst, this is a very clumbsy description. At the most distal link in the kinetic chain, how can the foot and leg come to a dead stop during heel striking? (remember, these are his words, on his website, for all to see and misunderstand) Does he clarify anywhere the duration in ms of this static configuration?. It just is not logical or indeed correct. Furthermore, using the 'effective mass" theory, a thoery that as Benno Nigg pointed out he, Benno, develpoed int he mid 90's, is applying a static theory to real dynamic function, and is making no recognition that the magnitude of GRF's is multifactorial, and 'effective mass" does not seem to be a major contributing factor. Benno stated this in the course of the debate. What Lieberman needs to be talking about are 1. torque/moments of each joint. It is simple - the torque/moment at the knee joint drops a bit when the forefoot is loaded, but the torque/moment at the ankle increases a lot 2. shock at the tibia.. previous studies, including one by Irene Davis herself, have shown that people who FF strike have INCREASED tibial shock. This is thought to be because of a couple of mechanisms, including increased knee stiffness ( the knee angle does not change as much when FF striking) and an increase in GRF. Here is an excerpt directly from one of Irene's papers
“The greater peak acceleration in the FFS (forefoot strike) may also be related to peak forces. On average, the FFS pattern resulted in greater vertical GRF (ground reaction force) peaks by 16% of body weight, or an average force difference of 104 Newtons. Previous studies have also reported greater peak vertical GRFs with an FFS pattern (McClay & Manal, 1995b; Oakley & Pratt, 1988). This difference was significant and most likely contributed to the greater amount of tibial acceleration in the FFS pattern. Finally, it is important to note that the heel pad of the foot provides an additional mechanism of shock attenuation in the RFS vs. the FFS. The smaller peak acceleration values of the RFS (rearfoot strike) and greater vertical GRF force peaks in the FFS pattern may be due, in part, to the ability of the heel pad to absorb a substantial amount of energy (Valiant & Cavanagh, 1985).
Liebermans website also states 'the change in the velocity of the effective mass does not differ significantly between a heel strike and a forefoot strike" .. this is using an overly simplistic undergraduate physics to explain an extremely complex biomechanical phenomenon. How can the change in velocity be equal?? The different landing patterns will enable different amounts of motion at impact. Therefore, subsequent kinematics will be different. I undersatnd his website should not include complex biomechanical theory, but he is using it to justify his own views on barefoot running and forefoot strike, and these veiw are not accurate. I also challenge the importance and relevance of this focus on the primary impact transient Fz1. Shorten (2011) has publish a paper entitled (and concluding), the "heel impact' force peak is neither "heel' nor 'impact' and does not quantify shoe cushioning effects (Footwear Science, 3,1:41-58). This paper implies the 'impact transient' is not actually measuring impact. it is far too contaminated by low frequency forces which have nothing to do with the accelerations occuring in response to ground contact.
This is why Irene Davis found that tibial accelerations ( a DIRECT measurement of impact transients/forces), was INCREASED when forefoot striking. Lieberman's core argument for saying barefoot running is superior (impact forces) is fatally flawed, and in actuality is the opposite. Impact forces are INCREASED when running with a forefoot strike!
I hope this does not sound like a winge, but I believe I do have a rudimentary grasp of the issues at hand, and my only concern is that if someone, especially someone with the influence of Daniel Lieberman, is going to go into print on a website people will read and beleive, he need to report the issues accurately and not make them fit his own personal theory.
Pete Larson is a College Professor who has run 5 marathons.
He blogs intelligently on Runblogger.com & also contributed to the debate thus:
I've just published a paper on foot strike patterns in marathoners. This was a mostly recreational population, but approximately 90% contact first on the heel (this was filmed at 300fps, so quite fast), and heel striking frequency increases from mile 6 to mile 20. Almost all were wearing traditional shoes (it was 2009, before minimalist really took off).
Obviously we don't have data on center of pressure or loading since it was a road race, but when looking just at contact I cannot imagine that anything even approaching 80% forefoot strikers is possible unless maybe you are looking at an elite track race. Nobody has published numbers like that. Now in my video from the NYC barefoot run, I'd say 80% midfoot or forefoot is a reasonable estimate, but have not tallied the data yet.
Filmed at 300 frames per second, note on the video the variation in foot strike patterns demonstrating that there are not necessarily consistent styles of running when exercising barefoot or with shoes.
Simon Bartold has commented on the Ross Tucker Blog:
Hi Ross.. nice precis of the debate. If I might just make a few comments that I think may have been missed. The first is that it was not ASICS that were concerned so much about hostilities, although of course they knew this had to be managed, but rather the conference management, and in particular Lieberman. I was actually told 12 hours before the debate that he had insisted on including a 6th speaker, his friend and barefoot coach Lee Saxby, because he was concerned the barefoot argument had been highjacked by ASICS. Given the composition of the panel and your own presence, this seemed highly inappropriate, and smacked of insecurities of his own "theories". If you are going to work in the kitchen, at some point one has to take the heat.
You made the comment " But it led to an argument, because I think Simon Berthold misunderstood the point of the analogy. He had printed off Lieberman's website explaining barefoot running and adamantly criticised Lieberman's explanation. "
I think that is a pity, because I understand the analogy exactly. The point I was making is that Lieberman says in his webpage that the" foot and leg come to a dead stop". It is there for all to read. Sorry, at heal strike the foot and leg do not come to a dead stop, and the problem I have with this is that people read his site and naturally assume that if he says it it is gospel, (a little like the Nature article, but that is another debate). What he says is taking a rigid model of the foot and leg and failing to understand he is applying it to a dynamic system. At the very worst, this is a very clumbsy description. At the most distal link in the kinetic chain, how can the foot and leg come to a dead stop during heel striking? (remember, these are his words, on his website, for all to see and misunderstand) Does he clarify anywhere the duration in ms of this static configuration?. It just is not logical or indeed correct. Furthermore, using the 'effective mass" theory, a thoery that as Benno Nigg pointed out he, Benno, develpoed int he mid 90's, is applying a static theory to real dynamic function, and is making no recognition that the magnitude of GRF's is multifactorial, and 'effective mass" does not seem to be a major contributing factor. Benno stated this in the course of the debate. What Lieberman needs to be talking about are 1. torque/moments of each joint. It is simple - the torque/moment at the knee joint drops a bit when the forefoot is loaded, but the torque/moment at the ankle increases a lot 2. shock at the tibia.. previous studies, including one by Irene Davis herself, have shown that people who FF strike have INCREASED tibial shock. This is thought to be because of a couple of mechanisms, including increased knee stiffness ( the knee angle does not change as much when FF striking) and an increase in GRF. Here is an excerpt directly from one of Irene's papers
“The greater peak acceleration in the FFS (forefoot strike) may also be related to peak forces. On average, the FFS pattern resulted in greater vertical GRF (ground reaction force) peaks by 16% of body weight, or an average force difference of 104 Newtons. Previous studies have also reported greater peak vertical GRFs with an FFS pattern (McClay & Manal, 1995b; Oakley & Pratt, 1988). This difference was significant and most likely contributed to the greater amount of tibial acceleration in the FFS pattern. Finally, it is important to note that the heel pad of the foot provides an additional mechanism of shock attenuation in the RFS vs. the FFS. The smaller peak acceleration values of the RFS (rearfoot strike) and greater vertical GRF force peaks in the FFS pattern may be due, in part, to the ability of the heel pad to absorb a substantial amount of energy (Valiant & Cavanagh, 1985).
Liebermans website also states 'the change in the velocity of the effective mass does not differ significantly between a heel strike and a forefoot strike" .. this is using an overly simplistic undergraduate physics to explain an extremely complex biomechanical phenomenon. How can the change in velocity be equal?? The different landing patterns will enable different amounts of motion at impact. Therefore, subsequent kinematics will be different. I undersatnd his website should not include complex biomechanical theory, but he is using it to justify his own views on barefoot running and forefoot strike, and these veiw are not accurate. I also challenge the importance and relevance of this focus on the primary impact transient Fz1. Shorten (2011) has publish a paper entitled (and concluding), the "heel impact' force peak is neither "heel' nor 'impact' and does not quantify shoe cushioning effects (Footwear Science, 3,1:41-58). This paper implies the 'impact transient' is not actually measuring impact. it is far too contaminated by low frequency forces which have nothing to do with the accelerations occuring in response to ground contact.
This is why Irene Davis found that tibial accelerations ( a DIRECT measurement of impact transients/forces), was INCREASED when forefoot striking. Lieberman's core argument for saying barefoot running is superior (impact forces) is fatally flawed, and in actuality is the opposite. Impact forces are INCREASED when running with a forefoot strike!
I hope this does not sound like a winge, but I believe I do have a rudimentary grasp of the issues at hand, and my only concern is that if someone, especially someone with the influence of Daniel Lieberman, is going to go into print on a website people will read and beleive, he need to report the issues accurately and not make them fit his own personal theory.
Pete Larson is a College Professor who has run 5 marathons.
He blogs intelligently on Runblogger.com & also contributed to the debate thus:
I've just published a paper on foot strike patterns in marathoners. This was a mostly recreational population, but approximately 90% contact first on the heel (this was filmed at 300fps, so quite fast), and heel striking frequency increases from mile 6 to mile 20. Almost all were wearing traditional shoes (it was 2009, before minimalist really took off).
 |
| From NYC Barefoot Run |
Obviously we don't have data on center of pressure or loading since it was a road race, but when looking just at contact I cannot imagine that anything even approaching 80% forefoot strikers is possible unless maybe you are looking at an elite track race. Nobody has published numbers like that. Now in my video from the NYC barefoot run, I'd say 80% midfoot or forefoot is a reasonable estimate, but have not tallied the data yet.
Remember, more of this topic to come
with the precis of the UKSEM debate coming soon on this blog!
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