posted May-28-2007 01:42 AM               

This is another good paper by Dr. Farley and her students.

Fundamentally her finding is that the runner’s mechanics is independent of surface stiffness.

“However, the total vertical displacement of the runner's centre of mass during ground contact remained the same (mean ‹ 5.3 cm) on all of the surfaces (p ‹ 0.8189; Figure 3b). … and kept the total vertical displacement of the centre of mass the same on all of the surfaces.”

I thought magnitude of the numbers was interesting. These subjects ran at 5 m/s or 26.82/5 = 5:14 min/mile. That’s pretty fast. And the softest surface was ~15KN/m, which is close to the actual leg stiffness. That gave a surface that depresses about 7 cm or 3 inches with each step. I can’t imagine what kind of surface that would represent in the real world. Just an interesting thought.

There’s a good picture of a subject in an experiment on her website for the Locomotion Lab in Colorado.

http://www.colorado.edu/kines/Lab/Locomotion.html

It looks like the tread is pretty narrow. I bet that’s how they get the runner’s feet to consistently land on the force plate under the tread. I ordered a used force plate ($165 from Venier.com). It’s only 12” wide. Looking at their set up, I can see how I might bury it in the middle of the tread board and confine my steps to the plate. I’ll do some testing before I cut a hole in my machine for a silly experiment.

I came across a paper that she wrote with a grad student at an ASB conference. “Is the Leg Most Spring-Like at the Preferred Hopping and Running Frequencies?”

It’s at:

http://www.asbweb.org/conferences/2006/pdfs/319.pdf

I wrote to Mr. Moholkar. Maybe they have some data on the issue I mentioned above.

Ted

[This message has been edited by TedAndresen (edited May-28-2007).]

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posted May-28-2007 02:42 AM               

Thanks. This is interesting. The Moholkar and Farley study shows that the spring effect increases with step freqency. This is some rational for the conventional-wisdom recommendation to developing runners to increase their cadence. The quote you posted backs up the results of the Ferris report I found - running biomechanics (including COM movement) remain constant over a remarkably wide range of surface stiffnesses.

What are you thinking of measuring with your equipment?

-b

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posted May-28-2007 10:27 AM               

Something I read in the Ferris study made me wonder if would be possible to get quite far without measuring force at all.

I have not thought this through, just floating random ideas right now but...

It would be nice to do some studies that were not constrained to a runner passing over a plate or other short and restricted apparatus - this might be doable if it were not necessary to record force.

I am thinking of a normal athletics track. The data recorded is:
(i) COM vertical movement and timing - I guess this could be does with an accelerometer strapped to the runners waist. Can these things report at 200Hz?
(ii) Running speed.
(iii) Ground contact period and timing - I think a high-speed video camera was used in the Ferris (200 frames/sec) to examine the amount of the shoe in contact with the running surface. I am not sure if they used this to measure contact time.
(iv) Step rate

Anyway, with these data I guess it is possible to calculate leg compression. If the airtime is known, then the impulse supplied by the leg can also be known.

It would be interesting to see what happens when the same runner (a) runs at different speeds and (b) trains to run with a difference step rate.

BTW, when the Nike/Polar thing came out I was wondering if the next phase would be a whole slew of biometric data coming back from the shoes. If a shoe can be fitted with a device to measure ground contact time. If a HR monitor strap can be fitted with an accelerometer to measure vertical COM movement. Add some processing power... Such gadgetry could perhaps give a continuous readout of approximate running economy.

-b

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posted May-29-2007 05:02 AM               

The Moholkar and Farley study shows that the spring effect increases with step freqency. This is some rational for the conventional-wisdom recommendation to developing runners to increase their cadence.

I think that some recommend higher step rates because they see elite runners competing with higher step rates and conclude that that will make any runner faster. I ASSuME that elite runners are competing at their PSF's’when the run fast. I don't’believe that they are trying to run with step frequencies higher than their PSF’s at that speed. Elite runners may be faster because of other factors, such as, O2 consumption per mass and the relative mass of their body segments compared to their total body mass. (Their lower limbs my be slightly less massive, similar to the double-amputee, Oscar Petorius who can run at very high speeds.)

I think that the Moholkar and Farley study found that the legs were more spring-like a higher speeds and step frequencies. The model and experiment had closer agreement for CM displacement at higher step frequencies. That may not imply that it is better to run with a higher step frequency, just that the model tracks it more closely. It does say that the O2 consumption is a minimum at the PSF but it doesn’t say that it would be more efficient to run with a higher step frequency than the PSF.

“Surprisingly, the body coordinates the actions of many muscle-tendon units to make the overall stance leg behave like a spring at the PSF and higher frequencies. It is likely that the energetic cost of running is minimized at the PSF due to an optimal combination of high elastic energy storage/return and a low cost of generating force.”

I did some model fitting to a dataset I got from the University of Jena, Germany.

http://members.aol.com/EasyExperiments/SM_Graphs.gif

I had also had trouble fitting the CM displacement data. I was off by about 15% and I don’t know why. There seems to be something missing in the model. It’s not obvious to me.

The quote you posted backs up the results of the Ferris report I found - running biomechanics (including COM movement) remain constant over a remarkably wide range of surface stiffnesses.

I totally agree.

What are you thinking of measuring with your equipment?

There are two areas. The spring mass model predicts the vertical Ground Reaction Force (vGRF). If I stand on the force plate the vGRF would be my body weight (BW). If I run in place on the plate and one foot is always in contact with the ground (no aerial phase), the maximum vGRF should be less than 2 BW. If I leave the ground and have an aerial phase while running in place, the maximum vGRF should be greater than 2 BW. I want to see that experimentally.

If I drop a basketball on the force plate the shape of the vGRF curve should be a symmetric sort of bell-shaped curve. I want to see that.

If I drop a 2x4 with a coiled spring on the end of it on the force plate the shape of the vGRF curve should be a symmetric and have a contact time that the spring mass model can predict. I want to test that.

If the plate passes those tests I can run in place on it and find the force versus compression curve for a leg. If the leg acts like a spring, the curve should be a straight line. If it is not a straight line, I want to see what type curve it is; concave up or convex up. That would possibly explain some of the shortcomings in assuming that the legs acts as linear springs. Of course, I’ll have to hyjack some other runners to test any findings.

If this checks out I would mount the plate in my dreadmill and see if the predicted vGRF versus speed agrees with the measured vGRF.

Something I read in the Ferris study made me wonder if would be possible to get quite far without measuring force at all.

I have not thought this through, just floating random ideas right now but...

It would be nice to do some studies that were not constrained to a runner passing over a plate or other short and restricted apparatus - this might be doable if it were not necessary to record force.

I have done a tremendous amount of work on my treadmill with a video recorder. I painted a calibration stripe on the tread and measured my step rate at different speeds. From that I was able to construct a step-frequency versus speed curve for myself. From my running in place step frequency I was able to calculate my leg stiffness (15.700 KN/m) and use that to generate a step-frequency versus speed from the spring mass model.

I am thinking of a normal athletics track. The data recorded is:

(i) COM vertical movement and timing - I guess this could be does with an accelerometer strapped to the runners waist. Can these things report at 200Hz?

Yes, but you could do that on a treadmill. I got an iMEM’s 3-axis accel from Analog.com.

http://www.analog.com/en/subCat/0,2879,764%255F800%255F0%255F%255F0%255F,00.html

It worked great. It needs to be packaged but I can see using it to check the CM displacement generated from the vGRF method.

(ii) Running speed.

I would think that it would be difficult to control the speed on a track unless you had a pacing cart that also carried the instrumentation.

(iii) Ground contact period and timing - I think a high-speed video camera was used in the Ferris (200 frames/sec) to examine the amount of the shoe in contact with the running surface. I am not sure if they used this to measure contact time.

I read that they have a good deal of trouble with that measurement because the uncertainty in determining the touch-down and toe-off times. The contact and separation events are not abrupt. I believe that the traditional approach is to use the leading and trailing sides of the vGRF curve to estimate the timing.

(iv) Step rate

This very easy with to do from a video.

It would be interesting to see what happens when the same runner (a) runs at different speeds and (b) trains to run with a difference step rate.

That is the kind of data that I will be looking for if I can get the swing leg model to work out.

Incidentally, the one measure that is difficult to capture on a treadmill is the horizontal Ground Reaction Force. That’s why some researchers prefer to have the subject run across a fixed plate. There must be 2-axes force plates.

BTW, when the Nike/Polar thing came out I was wondering if the next phase would be a whole slew of biometric data coming back from the shoes. If a shoe can be fitted with a device to measure ground contact time. If a HR monitor strap can be fitted with an accelerometer to measure vertical COM movement. Add some processing power... Such gadgetry could perhaps give a continuous readout of approximate running economy.

I had the same expectation, but now I don’t think that the market is ready to pay for or correctly use that level of technology.

Ted

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posted May-29-2007 09:33 PM               

There are shoe wearable inserts as force plates on the market, so individuality is easily measured.

First is the idea of spring stiffness of the muscles. One factor ignored so far is that for every mm of material between the bottom of your feet and the surface you run on, measurable alters your running biomechanics. The sensitivity for nerve ending interpretation simply through such a filter limits range of motion and thus slows a runner down.

Every shoe manufacturer knows statistically that the more money you spend on shoes, the slower you run and the more likely you are to injure yourself.

Landing biomechanics in runners are unique and measurably different to each different shoe product an individual wears. So elasticity is a variable to the equation, but every different shoe out there influences that running factor in negative ways. Thus separate elements of muscular elasticity are limited in broad-brush description.

I prefer purity of heart rate. No matter what a runner believes, if they change the way they move, it will only be in one of two directions, less efficient, or more efficient.

What’s unique to me is how the brain is fooled into believing a more comfortable way to run in their mind translates into a faster way to run.

And if it any biomechanic change is made, it’s done in only one of two ways. More efficient, then heart rate measurement will drop in beat count. Less efficient, then increase in beat count will prove the relative economy of any change one makes.

In the end, changes in biomechanics are simple in measure. A heart rate monitor tells all. The only relative aspect of relative economy, is that its unique to each individual. So the only common measurement a runner can make is if his oxygen, and thus energy, consumption decreases with any alteration they make. And that measurement is through one's heart rate.

What I learned is that the longer stride I took, my heart rate decreased in measurement compared with increasing any turnover rate.

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posted May-30-2007 09:51 AM               

Sounds like you are well kitted out with the essentials. It would be good to see the shape of the curves you get in your experiments with the force plate. Please don't keep them to yourself!

Two points about preferred step frequency:

People say elite runners all have similar PSF. This may not be a justification for slower runners to mimic this parameter since they are running more slowly. On the other hand, there might be a good argument for runners to train above their PSF, even though this is less efficient. This could be because it is stressful to run at a higher SF than you are used to. So, in races, when runners are moving faster a runner who had already trained at a higher SF (albeit at lower speeds) would have an advantage. This is the kind of logic I am using in my training. I am running all my runs easy right now, but trying to run with higher cadence since I feel it is easier to increase stride length than increase leg turnover.

The other point is that there are many variations of running style, espacially in slower runners. There is a wide range of PSF in hobby runners. There is no particular reason to believe that they are all running at the most efficient one for them. Or, if there is a structural reason (strength, leg weight, muscle tone, running form) it would be good to know it.
-b

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posted May-30-2007 10:10 AM               

quote:

---

Originally posted by sport jester:

There are shoe wearable inserts as force plates on the market, so individuality is easily measured.

---

quote:

---

First is the idea of spring stiffness of the muscles. One factor ignored so far is that for every mm of material between the bottom of your feet and the surface you run on, measurable alters your running biomechanics. The sensitivity for nerve ending interpretation simply through such a filter limits range of motion and thus slows a runner down.

---

quote:

---

And if it any biomechanic change is made, it’s done in only one of two ways. More efficient, then heart rate measurement will drop in beat count. Less efficient, then increase in beat count will prove the relative economy of any change one makes.

---

quote:

---

What I learned is that the longer stride I took, my heart rate decreased in measurement compared with increasing any turnover rate.

---

I have learned something a bit different. Changes in turnover can cause an exaggerated increase in HR until the system adapts. But when the system adapts higher turnover can be more efficient in terms of HR. Furthermore, the running form itself may have to be adapted to an increase in cadence. There are ways to run where is it hard to increase turnover, and increasing stride length is the only productive way to go faster.

[This message has been edited by brianfie (edited May-30-2007).]

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posted May-31-2007 12:25 PM               

Here’s an interesting link to the patents of a shoe wearable force plate…
http://www.patentstorm.us/patents/6122846-description.html

A company link is:
http://www.diashoe.com/generalinfo/conews-2003.htm

And to your point that people run the same when the surface underneath them changes is simply not true. Go spend a day walking or running on the beach and then step directly on concrete and your gait change will become blatantly obvious in adaptation.

There are also multiple studies to demonstrate running on a treadmill is biomechanically different than running on the street or track. Its one reason elite runners hate treadmill training, not to mention explains the social joke as to why treadmills become expensive clothes hangers in six months.

You make an interesting comment to my adaption comments of turnover rates. To that point I can tell you that in teaching runners, I can teach you to run 20% faster in about an hour and a half worth of time and I do it through increasing your stride length biomechanics.

For same speed comparison, I average a 20 beat per minute decrease in heart rate for given speed or even incline rates up to 7% incline in treadmill tests for Nike.

The body’s natural desire to cheat is what drives the turnover rate issue in my mind. Yes it makes for a more comfortable way to run, which I feel is what cons runners into thinking their running more efficiently. But the research shows it’s no improvement.

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posted May-31-2007 12:59 PM               

quote:

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Originally posted by sport jester:

---

That's a very interesting website. Good lead.

There are also multiple studies to demonstrate running on a treadmill is biomechanically different than running on the street or track.

Do you have any research links to back this up? I've seen a lot of unsubstantiated statements in the running media concerning this issue, but I've never found any legitimate research on this topic.

Do you know of any peer-reviewed journal studies on this topic?

[This message has been edited by TedAndresen (edited May-31-2007).]

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posted May-31-2007 02:00 PM               

One can start to imagine interesting ways to use such realtime readout of data.

What about a realtime feedback on degree of pronation. It would be interesting to see if people could train themselves to be neutral runners.

-b

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posted May-31-2007 03:06 PM            

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posted May-31-2007 09:39 PM               

Here’s one link. One I was truly looking to find wasn’t found on the biomechanic magazines archive search….

http://www.journals.elsevierhealth.com/periodicals/jclb/article/PIIS0268003301000614/abstract

Treadmills eliminate forward momentum for runners and your body has to compensate for that fact. Why do you think treadmills become expensive clothes hangers in about six months anyway if they didn't alter your biomechanics. As a runner you can utilize that fact to a training benefit.

I tell runners that no skill learned on a track or street training program will help you become a better treadmill runner. However learning the balance skills necessary to be a good treadmill runner will help you become a better street and track runner.

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posted May-31-2007 09:46 PM               

quote:

---

Originally posted by MichiganFlyer:
I was never under the impression that Pose made you a racer. From reading material on Pose it seems that it is an easier way to run. Gravity does the work and makes you fall forward but it doesn't make you faster. It seems to be a lazy way to run. If you are an occasional runner you may like to try out this form of running but I don't think many elites run this way if any.

---

Yes, yes, yes. I totally agree. That is the response I got from the POSE Institute when I queried them on a similar issue. Thank you for bring that point to the forefront.

Ted

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posted May-31-2007 10:49 PM               

Yes, they say its a more comfortable and not faster way to run. However in working with track athletes, the shoes they wear demand a forefoot landing no different than the Pose philosophy.

So if it isn't faster, then doesn't logic extrapolate to think that top sprinters can run faster?

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posted Jun-02-2007 04:16 AM               

quote:

---

Originally posted by sport jester:

---

This is a study if hip dynamics, not performance. In the concluding remarks they comment “it does not significantly alter the performance of the evaluated activity ".

"In order for the treadmill to be accepted as a useful research and/or clinical assessment instrument, it must be demonstrated that it does not significantly alter the performance of the evaluated activity. In this respect, a treadmill with minimal intra-stride belt speed variability and similar surface stiffness to the relevant overground condition is likely to be capable of being used to obtain a representation of the typical human running action for well accommodated subjects."

Treadmills eliminate forward momentum for runners and your body has to compensate for that fact.

It is a uniformly moving reference frame. Newtonian physics is the same in all uniformly moving reference frames. It is like some one running on the train platform to keep up with the train and someone running on the train running towards the back of a moving train so they are keeping up with the platform. They are both running under the same rules of physics.

Ted

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posted Jun-10-2007 11:47 PM               

The question is why treadmills become expensive clothes hangars in six months on average after purchasing. If they didn’t alter your walking or running biomechanics, then people wouldn’t stop using them.

There are three components isolated. First is measured by vision scientists as to the connection between what you see and how you walk. The intrinsic need of a human to view movement while it physically moves is a disconnect that effects your running efficiency.

http://www.journalofvision.org/1/3/4/

How your brain compensates for running on a moving field is also measurable different than running on a normal surface. The rearward travel of a treadmill’s belt completely alters the biomechanics of how you land which is the article I was seeking.

Momentum is a constant as you state, but it’s also a force which effects your natural weight transfer efficiency. It takes a greater amount of energy to remain upright and stable on a treadmill than our natural reliance to the forward momentum of firm surface running.

I’ve always stated, that no outdoor or track running will make you a better treadmill runner, however in learning the balance skills necessary to run on a treadmill will easily make you a better outdoor runner.

The less efficient your weight transfer skills, they become much easier to isolate on a treadmill than outdoors with ease.

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posted Jun-11-2007 11:52 AM            

The question is why treadmills become expensive clothes hangars in six months on average after purchasing. If they didn’t alter your walking or running biomechanics, then people wouldn’t stop using them.

They don't, you idiot. I sell high end exercise equipment for a living and a very high percentage of people who buy from us continue to use and get desired results from their treadmills for years. Plenty of serious runners do a majority of their training on treadmills. People who do not make the required comittment will see their treadmills become clothes hangers, not for any other reason.

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posted Jun-12-2007 05:22 AM               

quote:

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Originally posted by laker:
They don't ... I sell high end exercise equipment for a living and a very high percentage of people who buy from us continue to use and get desired results from their treadmills for years. Plenty of serious runners do a majority of their training on treadmills. People who do not make the required comittment will see their treadmills become clothes hangers, not for any other reason.

---

Laker,

Thank you for your comments. I agree with you.

Ted

[This message has been edited by TedAndresen (edited Jun-12-2007).]

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posted Jun-13-2007 02:54 PM               

A little bit of background for you and Ted; I’ve been in sports research for 15 years. My personal client list is up to and including NBA coaches as consultant in player physical development.

And besides humans, what other species of athlete have you trained?

As a surgical rehabilitation specialist of both racehorses and humans, my world is a little more broad based. In holding the reins of a thoroughbred, I can tell you that as an animal who lives to run, and bred to run, they’re scared to death of treadmills.

I’ve also worked in both entry level and high end sales of fitness products setting company sales records doing so in multi-state retail operations as well as for global sales for sports equipment manufacturers.

Oh, and not forgotten is conducting research work under the umbrella of Nike‘s Innovation Kitchen. Does the lead designer of every Air Jordan product and manager of their sports research lab accept your phone calls?

Simply selling treadmills doesn’t impress me… Your training is more from marketing departments, not science unless you can state otherwise…

What I can tell you is that running on a treadmill is radically different than hard surface running. Your foot landing biomechanics is measurably altered because you’re adjusting to the rearward motion of the belt upon impact. Just because you don’t understand that fact, doesn’t mean it doesn’t exist.

It may seem off the wall to yourself, but I’ve never lived in a world exclusive to humans. If everything humans believe were true, then like all theories, they should uphold for any athlete regardless of species. If running on a treadmill were truly identical to hard surface running, then a horse should have no problem with the transition as you so put forth as they run no different than humans do in locomotion (regardless of having four legs to our two).

Minor detail for you; horses on a treadmill panic. Humans are simply less aware of the differences in treadmill running biomechanics that a horse picks up immediately. Humans adjust easily to the difference, while I have to teach a horse how to do it.

They recognize the difference within their first few steps. Controlling a 125lb runner on a belt may seem easy to you, but calming a 1,200lb athlete with the ability to put a hoof through your face is a real struggle. If there truly were no difference, then a horse should have no problem with the surface transition since all they want to do is run.

It takes a lot of TLC to get a horse onto a treadmill and about two weeks until they become comfortable with the idea of even walking on the belt, let alone running on it. That fear and panic is my window of trust to introduce them to treadmill training and allow me to adjust their biomechanics.

Sure high end users can use a treadmill effectively, but the vast majority use it as a pacifier, not a training tool. For those who are purchasing a treadmill to get in shape, the balance alteration of using them as a novice will lead to strain on the hips, lower spine, and the anterior cruciate ligament no different than a racehorse.

No treadmill company is going to teach a salesperson the drawbacks to treadmill training, so your perspective is understandable.

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posted Jun-13-2007 05:21 PM            

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posted Jun-14-2007 05:52 AM               

There are also multiple studies to demonstrate running on a treadmill is biomechanically different than running on the street or track.

QUOTE]

this I don't doubt..I always think to myelf after a good hard run on a treadmill that it works the legs differently. I can't yet pinpoint how. But I swear their is SOMETTHING different going on.

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posted Jun-14-2007 02:28 PM               

I appreciated your addition to this discussion about treadmill sensitivity. Since a treadmill is a moving surface, and a street or track is fixed the math to say they‘re the same simply doesn‘t exist. Different surfaces require different push off and landing biomechanics.

The subtleties of difference is in one’s downward compression upon landing. On the street that motion is fluid as your body tightens to absorb your bodyweight and redirect it upwards for your next push off.

On a treadmill, the efficiency of weight transfer is altered because you have to compensate and fight the surface underneath you while it pulls your foot backwards. The foot adapts by reaching and landing slightly ahead of your natural footfall to allow for the increased and unnatural distance and time the foot will travel on the belt per step. On a fixed surface that transition is fluid while on a belt stability is much more complex.

To stop the rearward pull of the belt, your quads have to expend greater amounts of energy in balance transition with your bodyweight impact forces upon impact. As your bodyweight transfers over the foot to the push off phase, your calf muscles not only have to push you forward, but compensate for the rearward motion of the belt at the same time which increases the firing time of the muscle.

You obviously have racehorse sensitivity to how your body works.

Laker,

I’ll start with the fact that I was invited into Nike’s sports research lab to have my work analyzed by their top people. Not to mention spending last winter teaching my technique through their Niketown store’s running club.

I just finished a full track season with a young man who races for a small private college locally and running the 400 meter primarily. In comparison with teammates, as well as consistent opponents, his times improved in greater range running as I teach than with the time improvements of the control group averaged out over the season. Not to mention a full three seconds faster than his last season PR

Oh and he also ran 20% faster within a month of our meeting. Racing 20% faster was impacted because his coach refused to allow him to train properly, which Nike takes into account.

This fall, I’m working with an NCAA Big Sky Conference football program and one of my primary students and most eager to learn from me of the team already has one Heisman Trophy in his family.

I encounter a lot of people who think I’m full of it, and I’ll tell you that it’s gold plated…

To be honest, I really don’t care what hopper or anyone thinks, because the vast majority of people run for ego, not competition. So I only accept the opinions of people who I’ve taught personally, since they’re far more qualified to judge my work than any trailer porch self proclaimed “expert” in running. Yea, experts also said the world was flat…

In my studies With Nike, my technique was proven to average a 20 beat per minute decrease in heart rate compared with a traditional running technique for identical running speeds. The summary from their lab is that my running technique is a more efficient use of the hamstrings, calf muscles, and removes all lateral pressures to the ACL.

That’s Nike’s opinion, not mine, and obviously not hoppers. Let’s look….. Nike’s top biomechanic or Hopper… who would you bet knows more about running???

And for someone elses opinion, here’s a summary from one racing student from Niketown and written for the lab of his perspective of what I teach.

“Hello my name is Josh Cleary. I am 14. I run for Oregon Cross Country. I went to the regional meet for cross country but did not qualify for nationals. I have been running since 3rd grade. My PR in the 4k is 15:25. I train with Marcus Henry who was 3rd in the nation last year in the 3k at nationals. When tried running the way Robert showed me I felt a lot of strain come off my feet. They had a lot less impact with the ground. I felt like I was using less energy to do the same amount of work. My calf's were a little more tired
after running three miles Robert's way but otherwise the rest of my body felt like I could go on forever. I noticed I didn't have to breath as hard. I did feel like my calf's were being worked more than usual. I had only a tiny slight
bounce to my run compared to my usual constant up and down. I used my arms a lot less. I would recommend this way to Olympic Runners because they could
save a lot more energy by pretty much taking out arm movement and not bouncing up and down. The form is hard for me right now still because it is going against everything I was taught on how to run and what I run like naturally.
Once I do get it I think my times will dramatically improve."

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posted Jun-14-2007 11:13 PM               

Can you cite any scientific peer-reviewed research in any journals or a scientific publications to back up your assertions?

Ted

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posted Jun-15-2007 03:18 AM               

Back on topic of this thread. I am kind of accordance with the pose method as far as shoes go. I am running in racing flats for training along with some barefoot and I feel like it is making me stronger and improving form

quote:

---

Originally posted by sport jester:
Superburtm,

I appreciated your addition to this discussion about treadmill sensitivity. Since a treadmill is a moving surface, and a street or track is fixed the math to say they‘re the same simply doesn‘t exist. Different surfaces require different push off and landing biomechanics.

The subtleties of difference is in one’s downward compression upon landing. On the street that motion is fluid as your body tightens to absorb your bodyweight and redirect it upwards for your next push off.

On a treadmill, the efficiency of weight transfer is altered because you have to compensate and fight the surface underneath you while it pulls your foot backwards. The foot adapts by reaching and landing slightly ahead of your natural footfall to allow for the increased and unnatural distance and time the foot will travel on the belt per step. On a fixed surface that transition is fluid while on a belt stability is much more complex.

To stop the rearward pull of the belt, your quads have to expend greater amounts of energy in balance transition with your bodyweight impact forces upon impact. As your bodyweight transfers over the foot to the push off phase, your calf muscles not only have to push you forward, but compensate for the rearward motion of the belt at the same time which increases the firing time of the muscle.

You obviously have racehorse sensitivity to how your body works.

---

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posted Jun-15-2007 02:36 PM               

Which assertion, my running technique or the treadmill landing summary? If you recall, I noted trying to find the foot landing study and failing. I’m still hunting it…

Superburtm,

What you’re experiencing is a slight case of over striding. The tendons of the quads go through the kneecap and with landing impact forces your knee is getting pulled out of alignment.

IP: Logged