In my ongoing discussions with others regarding gait, the extensor paradox has been repeatedly used as "evidence" to support various claims. Essentially there's little activity as measured by EMG from the quadriceps once the body passes over the support foot. This has been used as evidence that there's no "pushing off' occurring because the knee isn't extending via quad contraction.
Two problems: First, the typical heel strike/overstriding gait uses a different muscle pattern than "natural" running gait. The original research was done around 1990. Odds are great that the subjects ran with the former.
Second, wouldn't the pushoff come more from hip extension versus knee extension? In other words, the quads shouldn't be especially active at that point because the glutes are doing most of the work.
Thoughts? Am I missing something obvious? I want to get some more feedback and discussion before writing a blog post about the topic.
Hopefully Pete will chime in. I remember that he talked about the shortcomings of their measurement technique maybe a year or two ago. IIRC, you can't really tell what muscles are activating without implanted electrodes. Ouch. Anyway, I'm probably remembering it wrong, so I'll shut up. I'd expect the glutes to be primary if you have good form. The quads and calves should provide elastic storage and rebound.
Anytime you have a paradox, it means that you don't understand what's going on. Sounds to me like some Posers have you in a corner and are taking turns beating on you. Good luck. LOL
On Friday, November 9, 2012 7:30:25 AM UTC-7, Jason Robillard wrote:
> In my ongoing discussions with others regarding gait, the extensor paradox > has been repeatedly used as "evidence" to support various claims. > Essentially there's little activity as measured by EMG from the quadriceps > once the body passes over the support foot. This has been used as evidence > that there's no "pushing off' occurring because the knee isn't extending > via quad contraction.
> Two problems: First, the typical heel strike/overstriding gait uses a > different muscle pattern than "natural" running gait. The original research > was done around 1990. Odds are great that the subjects ran with the former.
> Second, wouldn't the pushoff come more from hip extension versus knee > extension? In other words, the quads shouldn't be especially active at that > point because the glutes are doing most of the work.
> Thoughts? Am I missing something obvious? I want to get some more feedback > and discussion before writing a blog post about the topic.
> In my ongoing discussions with others regarding gait, the extensor paradox
> has been repeatedly used as "evidence" to support various claims.
> Essentially there's little activity as measured by EMG from the quadriceps
> once the body passes over the support foot. This has been used as evidence
> that there's no "pushing off' occurring because the knee isn't extending
> via quad contraction.
> Two problems: First, the typical heel strike/overstriding gait uses a
> different muscle pattern than "natural" running gait. The original research
> was done around 1990. Odds are great that the subjects ran with the former.
> Second, wouldn't the pushoff come more from hip extension versus knee
> extension? In other words, the quads shouldn't be especially active at that
> point because the glutes are doing most of the work.
> Thoughts? Am I missing something obvious? I want to get some more feedback
> and discussion before writing a blog post about the topic.
Something has to happan to get the body airborne.
Possible contributors:
Hip extensors
Quads
Muscles which control pelvic position (don't know what they're
called).
Tiny contribution from calves.
Question: How do I know that any EMG tests done in the past were done
correctly?
This is a topic of my current blog post... how can we rely on any running research given the incredible variability of individual differences in gait, thus differences in muscle activation, stress, etc.
And Gordo- I didn't want to turn this into another "what's wrong with Pose" thread, but the issue was brought up by a Pose proponent as evidence of the effects of gravity on locomotion. That brought up the wider issue of the paradox- namely whether it was even a paradox at all.
On Friday, November 9, 2012 2:42:15 PM UTC, Dan Mozell wrote:
> On Nov 9, 9:30 am, Jason Robillard <robilla...@gmail.com> wrote: > > In my ongoing discussions with others regarding gait, the extensor > paradox > > has been repeatedly used as "evidence" to support various claims. > > Essentially there's little activity as measured by EMG from the > quadriceps > > once the body passes over the support foot. This has been used as > evidence > > that there's no "pushing off' occurring because the knee isn't extending > > via quad contraction.
> > Two problems: First, the typical heel strike/overstriding gait uses a > > different muscle pattern than "natural" running gait. The original > research > > was done around 1990. Odds are great that the subjects ran with the > former.
> > Second, wouldn't the pushoff come more from hip extension versus knee > > extension? In other words, the quads shouldn't be especially active at > that > > point because the glutes are doing most of the work.
> > Thoughts? Am I missing something obvious? I want to get some more > feedback > > and discussion before writing a blog post about the topic.
> Something has to happan to get the body airborne. > Possible contributors: > Hip extensors > Quads > Muscles which control pelvic position (don't know what they're > called). > Tiny contribution from calves.
> Question: How do I know that any EMG tests done in the past were done > correctly?
I agree. Use the EMG on some East Africans and then maybe come to some conclusions. Just finishing "Anatomy for Runners" and he puts a lot of emphasis on improving hip flexor flexibility and hip extensor (glute max) strength. Seems like there is a whole lot more forward propulsion from hip extension going on during running than the hip flexion and knee extension the quads provide. I know when I'm sore I really just feel the quads screaming as they absorb impact until like Jason said, the leg begins to pass under me.
On Friday, November 9, 2012 9:01:03 AM UTC-6, Jason Robillard wrote:
> This is a topic of my current blog post... how can we rely on any running > research given the incredible variability of individual differences in > gait, thus differences in muscle activation, stress, etc.
> And Gordo- I didn't want to turn this into another "what's wrong with > Pose" thread, but the issue was brought up by a Pose proponent as evidence > of the effects of gravity on locomotion. That brought up the wider issue of > the paradox- namely whether it was even a paradox at all.
> On Friday, November 9, 2012 2:42:15 PM UTC, Dan Mozell wrote:
>> On Nov 9, 9:30 am, Jason Robillard <robilla...@gmail.com> wrote: >> > In my ongoing discussions with others regarding gait, the extensor >> paradox >> > has been repeatedly used as "evidence" to support various claims. >> > Essentially there's little activity as measured by EMG from the >> quadriceps >> > once the body passes over the support foot. This has been used as >> evidence >> > that there's no "pushing off' occurring because the knee isn't >> extending >> > via quad contraction.
>> > Two problems: First, the typical heel strike/overstriding gait uses a >> > different muscle pattern than "natural" running gait. The original >> research >> > was done around 1990. Odds are great that the subjects ran with the >> former.
>> > Second, wouldn't the pushoff come more from hip extension versus knee >> > extension? In other words, the quads shouldn't be especially active at >> that >> > point because the glutes are doing most of the work.
>> > Thoughts? Am I missing something obvious? I want to get some more >> feedback >> > and discussion before writing a blog post about the topic.
>> Something has to happan to get the body airborne. >> Possible contributors: >> Hip extensors >> Quads >> Muscles which control pelvic position (don't know what they're >> called). >> Tiny contribution from calves.
>> Question: How do I know that any EMG tests done in the past were done >> correctly?
> This is a topic of my current blog post... how can we rely on any running
> research given the incredible variability of individual differences in
> gait, thus differences in muscle activation, stress, etc.
> And Gordo- I didn't want to turn this into another "what's wrong with
> Pose" thread, but the issue was brought up by a Pose proponent as evidence
> of the effects of gravity on locomotion. That brought up the wider issue of
> the paradox- namely whether it was even a paradox at all.
> On Friday, November 9, 2012 2:42:15 PM UTC, Dan Mozell wrote:
>> On Nov 9, 9:30 am, Jason Robillard <robilla...@gmail.com> wrote:
>> > In my ongoing discussions with others regarding gait, the extensor
>> paradox
>> > has been repeatedly used as "evidence" to support various claims.
>> > Essentially there's little activity as measured by EMG from the
>> quadriceps
>> > once the body passes over the support foot. This has been used as
>> evidence
>> > that there's no "pushing off' occurring because the knee isn't
>> extending
>> > via quad contraction.
>> > Two problems: First, the typical heel strike/overstriding gait uses a
>> > different muscle pattern than "natural" running gait. The original
>> research
>> > was done around 1990. Odds are great that the subjects ran with the
>> former.
>> > Second, wouldn't the pushoff come more from hip extension versus knee
>> > extension? In other words, the quads shouldn't be especially active at
>> that
>> > point because the glutes are doing most of the work.
>> > Thoughts? Am I missing something obvious? I want to get some more
>> feedback
>> > and discussion before writing a blog post about the topic.
>> Something has to happan to get the body airborne.
>> Possible contributors:
>> Hip extensors
>> Quads
>> Muscles which control pelvic position (don't know what they're
>> called).
>> Tiny contribution from calves.
>> Question: How do I know that any EMG tests done in the past were done
>> correctly?
Well, I wouldn't expect a LOT of quad input during pushoff. Pushing the lowers leg forward would provide a braking action in addition to the downward force. I would expect the hip extensors and calves to provide the most push, and maybe the hamstrings, since those are some of the only muscles in the chain that provide a downward or backward force component. Braking force right before lift off seems very counterproductive. Even if most of the quads effort could be directed downward, it would be by counteraction from other muscles, so it still seems counterproductive. I'm not saying I doubt they fire, only that I wouldn't be surprised if they didn't.
As a kid, I assumed the quads were the most important muscle for running, so I always wondered why football players and sprinters seemed to pull their hamstrings. ;)
On Friday, November 9, 2012 6:40:47 AM UTC-8, gordo wrote:
> Hopefully Pete will chime in. I remember that he talked about the > shortcomings of their measurement technique maybe a year or two ago. IIRC, > you can't really tell what muscles are activating without implanted > electrodes. Ouch. Anyway, I'm probably remembering it wrong, so I'll shut > up. I'd expect the glutes to be primary if you have good form. The quads > and calves should provide elastic storage and rebound.
> Anytime you have a paradox, it means that you don't understand what's > going on. Sounds to me like some Posers have you in a corner and are taking > turns beating on you. Good luck. LOL
> Gordo
> On Friday, November 9, 2012 7:30:25 AM UTC-7, Jason Robillard wrote:
>> In my ongoing discussions with others regarding gait, the extensor >> paradox has been repeatedly used as "evidence" to support various claims. >> Essentially there's little activity as measured by EMG from the quadriceps >> once the body passes over the support foot. This has been used as evidence >> that there's no "pushing off' occurring because the knee isn't extending >> via quad contraction.
>> Two problems: First, the typical heel strike/overstriding gait uses a >> different muscle pattern than "natural" running gait. The original research >> was done around 1990. Odds are great that the subjects ran with the former.
>> Second, wouldn't the pushoff come more from hip extension versus knee >> extension? In other words, the quads shouldn't be especially active at that >> point because the glutes are doing most of the work.
>> Thoughts? Am I missing something obvious? I want to get some more >> feedback and discussion before writing a blog post about the topic.
> In my ongoing discussions with others regarding gait, the extensor paradox
> has been repeatedly used as "evidence" to support various claims.
> Essentially there's little activity as measured by EMG from the quadriceps
> once the body passes over the support foot. This has been used as evidence
> that there's no "pushing off' occurring because the knee isn't extending
> via quad contraction.
> Two problems: First, the typical heel strike/overstriding gait uses a
> different muscle pattern than "natural" running gait. The original research
> was done around 1990. Odds are great that the subjects ran with the former.
> Second, wouldn't the pushoff come more from hip extension versus knee
> extension? In other words, the quads shouldn't be especially active at that
> point because the glutes are doing most of the work.
> Thoughts? Am I missing something obvious? I want to get some more feedback
> and discussion before writing a blog post about the topic.
Correct, it is only a paradox if the running model is based on active push-off. The muscles go 'silent' automatically when there is no or disappearing body weight. Not talking about Pose, just how muscles work, muscles need a point of support.
On Friday, November 9, 2012 8:14:31 AM UTC-7, Tuck wrote:
> Generally if you find a paradox it means there's something wrong with your > theory...
That's so consistently right that I might just have to add it to my list of (tentatively)universal truths. Now I've got a list. Before, I only had one entry, and it's hard to call that a list. ;)
On Friday, November 9, 2012 8:51:39 AM UTC-7, Jay Fox wrote:
> I would expect the hip extensors and calves to provide the most push, and > maybe the hamstrings, since those are some of the only muscles in the > chain that provide a downward or backward force component.
The hamstrings are too small and weak for this to be likely. Because they cross two joints, they will be most efficient at pulling the lower leg backward when your hip goes into flexion. In running that would serve to bring the foot back under the body and reduce the forward speed of the foot to zero at touchdown. Seems reasonable to me.
On Fri, Nov 9, 2012 at 11:52 AM, gordo <gaj...@gmail.com> wrote:
> On Friday, November 9, 2012 8:14:31 AM UTC-7, Tuck wrote:
>> Generally if you find a paradox it means there's something wrong with
>> your theory...
> That's so consistently right that I might just have to add it to my list
> of (tentatively)universal truths. Now I've got a list. Before, I only had
> one entry, and it's hard to call that a list. ;)
On Friday, November 9, 2012 9:47:27 AM UTC-7, JasonH wrote:
> Correct, it is only a paradox if the running model is based on active > push-off. The muscles go 'silent' automatically when there is no or > disappearing body weight. Not talking about Pose, just how muscles work, > muscles need a point of support.
Technically, only the support muscles would go silent. If, for example, you were pulling with your hamstring after the foot left the ground, then it would be active. Other muscles are very much active during the airborne phase, there's a lot going on.
I've always though Descartes was a little off.... "Sentio" fits better with my world view. And that's about as close to religion or philosophy that I'll dare to get on this list.
:-)
/Sean
On Nov 9, 2012, at 12:02 PM, gordo <gaj...@gmail.com> wrote:
The "generally" there is important, because the exception you could drive a
horse (or a galaxy) through is the black hole. The singularity (black
hole) was understood originally to be a flaw Einstein's General Relativity,
because "everyone knew" that such a thing couldn't exist.
On Fri, Nov 9, 2012 at 11:52 AM, gordo <gaj...@gmail.com> wrote:
> On Friday, November 9, 2012 8:14:31 AM UTC-7, Tuck wrote:
>> Generally if you find a paradox it means there's something wrong with
>> your theory...
> That's so consistently right that I might just have to add it to my list
> of (tentatively)universal truths. Now I've got a list. Before, I only had
> one entry, and it's hard to call that a list. ;)
'Second, wouldn't the pushoff come more from hip extension versus knee extension? In other words, the quads shouldn't be especially active at that point because the glutes are doing most of the work.'
Yes, the gluteus does most part of the work, they are the bigger. But I think that it's true that those muscles (gluteus and quads) doesn't need to work too much once the body mass passes the support point. Once you are at speed, the only need for horizontal forces (like the generated by pushing off after body passes support) is to counteract the opposing forces. This opposing forces are air friction (null if you run on treadmill) and your own generated friction (which can be minimized a lot via a proper technique, like the one you learn by running barefoot). This horizontal forces are low enough to be generated during the first phase of contact (mild paw back). If you generate greater horizontal forces than friction forces, you accelerate, and if you push off aggressively on every step, you will accelerate at every step... unless you also brake on every step (by striking your feet too forward), which is very inefficient.
So my theory is that gluteus (mainly) and quads are used only for vertical pushing. The horizontal forces are minimal compared to vertical and are generated via mild paw back. Maybe a minimal part of this (also minimal) horizontal forces is generated by leg extension, but I think that this is residual and inefficient, as this kind of push off requires that you keep your foot on the ground, which is tremendously inefficient. For fast acceleration, I think that we use an aggressive paw back combined with push off, but changing the whole posture of the body (when accelerating fast, you lean forward a lot).
Of course, these are only my thoughts, that coincide with what I feel when running with barefoot technique and that also fits in the 'extensor paradox'. For the little I still remember, I think that this was a whole distinct picture when I was a heel striker...
On Friday, 9 November 2012 15:30:25 UTC+1, Jason Robillard wrote:
> In my ongoing discussions with others regarding gait, the extensor paradox > has been repeatedly used as "evidence" to support various claims. > Essentially there's little activity as measured by EMG from the quadriceps > once the body passes over the support foot. This has been used as evidence > that there's no "pushing off' occurring because the knee isn't extending > via quad contraction.
> Two problems: First, the typical heel strike/overstriding gait uses a > different muscle pattern than "natural" running gait. The original research > was done around 1990. Odds are great that the subjects ran with the former.
> Second, wouldn't the pushoff come more from hip extension versus knee > extension? In other words, the quads shouldn't be especially active at that > point because the glutes are doing most of the work.
> Thoughts? Am I missing something obvious? I want to get some more feedback > and discussion before writing a blog post about the topic.
Quads are active in absorption - they prevent the knee from collapsing at landing. You don't want continued strong activity of the quads through midstance or you prematurely straighten the leg and get excessive vertical movement. What goes up must come down, and gravity is not our friend in running, so excessive vertical movement would be very inefficient. So the fact that the quads are not active past midstance isn't much of a paradox, it's simply how humans should run.
If you look at EMG studies that we have, the only muscles (ignoring those involved in mediolateral stabilization) that show much activity past midstance are the gastrocnemius, hamstrings, and toe flexors (the glute max does trail off a bit more slowly than the quads). Here's a cool figure showing activity for a bunch of muscles in walking and running: http://jn.physiology.org/content/95/6/3426/F3.large.jpg
On Friday, November 9, 2012 9:30:25 AM UTC-5, Jason Robillard wrote:
> In my ongoing discussions with others regarding gait, the extensor paradox > has been repeatedly used as "evidence" to support various claims. > Essentially there's little activity as measured by EMG from the quadriceps > once the body passes over the support foot. This has been used as evidence > that there's no "pushing off' occurring because the knee isn't extending > via quad contraction.
> Two problems: First, the typical heel strike/overstriding gait uses a > different muscle pattern than "natural" running gait. The original research > was done around 1990. Odds are great that the subjects ran with the former.
> Second, wouldn't the pushoff come more from hip extension versus knee > extension? In other words, the quads shouldn't be especially active at that > point because the glutes are doing most of the work.
> Thoughts? Am I missing something obvious? I want to get some more feedback > and discussion before writing a blog post about the topic.
On Saturday, November 10, 2012 3:40:00 PM UTC-5, Oblinkin wrote:
> Quads are active in absorption - they prevent the knee from collapsing at > landing. You don't want continued strong activity of the quads through > midstance or you prematurely straighten the leg and get excessive vertical > movement. What goes up must come down, and gravity is not our friend in > running, so excessive vertical movement would be very inefficient. So the > fact that the quads are not active past midstance isn't much of a paradox, > it's simply how humans should run.
> If you look at EMG studies that we have, the only muscles (ignoring those > involved in mediolateral stabilization) that show much activity past > midstance are the gastrocnemius, hamstrings, and toe flexors (the glute max > does trail off a bit more slowly than the quads). Here's a cool figure > showing activity for a bunch of muscles in walking and running: > http://jn.physiology.org/content/95/6/3426/F3.large.jpg
> On Friday, November 9, 2012 9:30:25 AM UTC-5, Jason Robillard wrote:
>> In my ongoing discussions with others regarding gait, the extensor >> paradox has been repeatedly used as "evidence" to support various claims. >> Essentially there's little activity as measured by EMG from the quadriceps >> once the body passes over the support foot. This has been used as evidence >> that there's no "pushing off' occurring because the knee isn't extending >> via quad contraction.
>> Two problems: First, the typical heel strike/overstriding gait uses a >> different muscle pattern than "natural" running gait. The original research >> was done around 1990. Odds are great that the subjects ran with the former.
>> Second, wouldn't the pushoff come more from hip extension versus knee >> extension? In other words, the quads shouldn't be especially active at that >> point because the glutes are doing most of the work.
>> Thoughts? Am I missing something obvious? I want to get some more >> feedback and discussion before writing a blog post about the topic.
On Saturday, November 10, 2012 3:41:45 PM UTC-5, Oblinkin wrote:
> Should have said gastroc/soleus, not just gastroc.
> On Saturday, November 10, 2012 3:40:00 PM UTC-5, Oblinkin wrote:
>> Quads are active in absorption - they prevent the knee from collapsing at >> landing. You don't want continued strong activity of the quads through >> midstance or you prematurely straighten the leg and get excessive vertical >> movement. What goes up must come down, and gravity is not our friend in >> running, so excessive vertical movement would be very inefficient. So the >> fact that the quads are not active past midstance isn't much of a paradox, >> it's simply how humans should run.
>> If you look at EMG studies that we have, the only muscles (ignoring those >> involved in mediolateral stabilization) that show much activity past >> midstance are the gastrocnemius, hamstrings, and toe flexors (the glute max >> does trail off a bit more slowly than the quads). Here's a cool figure >> showing activity for a bunch of muscles in walking and running: >> http://jn.physiology.org/content/95/6/3426/F3.large.jpg
>> On Friday, November 9, 2012 9:30:25 AM UTC-5, Jason Robillard wrote:
>>> In my ongoing discussions with others regarding gait, the extensor >>> paradox has been repeatedly used as "evidence" to support various claims. >>> Essentially there's little activity as measured by EMG from the quadriceps >>> once the body passes over the support foot. This has been used as evidence >>> that there's no "pushing off' occurring because the knee isn't extending >>> via quad contraction.
>>> Two problems: First, the typical heel strike/overstriding gait uses a >>> different muscle pattern than "natural" running gait. The original research >>> was done around 1990. Odds are great that the subjects ran with the former.
>>> Second, wouldn't the pushoff come more from hip extension versus knee >>> extension? In other words, the quads shouldn't be especially active at that >>> point because the glutes are doing most of the work.
>>> Thoughts? Am I missing something obvious? I want to get some more >>> feedback and discussion before writing a blog post about the topic.
