Does sports science research influence practice?

[Guest guest]

If the clinic directors didn't see a practical application to the

Weyand/Bundle research, they wouldn't have invited them to speak. This was a

coaching

seminar and not a biomechanics symposium. coordinated the

program. There were several Olympic medal winners who attended.

If you're looking for specifics as to how we are applying the research, go

to Barry Ross's site. All is free, with the exception of the speed tables,

which we are not allowed to release because the algorithm is property of Rice

University. We are in the process of negotiating with Rice for rights to make

the tables available to the public.

Ken Jakalski

Lisle High School

Lisle, IL

[Guest guest]

Barry wrote:

<<Hi Dr. Yessis,

Here are my matching responses, as you requested,to your questions:

(1) Yes, limb speeds can be the same. You can see this in action by

going to www.bearpowered.com/resources, then clicking on The Saga of

2 Runners. What you will see is that both runners are landing at the

same time, stride after stride, yet in a 100m race the faster of the

two is faster by 1 meter per second faster. If you watch the grounded

foot of each runner, you will see that the faster one's foot leaves

the ground increasingly earlier than the other. This allows more air

time to reposition his leg for the next stride. Weyand's study

mentions precisely what you see in the video, " Faster runners applied

greater forces during briefer contact periods, whereas slower runners

applied lesser ground forces during longer contact periods. "

The faster runner needs no more time to reposition limbs then slower

runner uses.

Interestingly, stride frequency does increase ( " The large

sensitivity of top speeds to small differences in the mass-specific

support forces applied to the running surface resulted from the

positive effect of support forces on maximal stride frequencies. "

Weyand, et al.). What is the cause of the faster stride frequency?

" Stride time (measured in s) was defined in accordance with Heglund

et al. as the time between consecutive footfalls of the same foot "

and " Stride frequency was determined from the inverse of the total

stride time (1/total stride time). "

Stride frequency, as determined above, improved because of the

shorter contact time of the faster runner. All of this is driven by

mass specific support force.

In answer to your question regarding distance covered, yes the faster

runner is covering more ground as he easily pulls away, but he

doesn't have to move limbs faster to do so. It's not individual limb

speed that's critical, it the speed of the body that must be

considered.

(2) You are correct in saying that force equals mass times

acceleration.

Where the problem lies for most is in recognizing that gravity pulls

the runner back to the ground and would continue accelerate the

runners mass until it hits terminal velocity (which won't happen to a

sprinter, so it's not really in issue here). In other words, the

airborne runner is now no different than any falling, accelerating

mass.

The opposite side of the amount of force created by the accelerating

mass of the runner striking the ground is what ground reaction force

plates measure. Newton's 3rd Law states that this measured force must

be equal to the force the runner hits the ground with. That force is

equal to 3 times bodyweight or more. The runner did not create this

force through chemical muscle power, but instead by merely hitting

the ground as a falling, accelerating mass. That is pure,

unadulterated physics.

Ground support force is the amount of force the runner must apply to

the ground so as not to collapse from the impact (support) and to

take maximum advantage of the force that will be returned by the

ground (Newton's 3rd law). This force applied by the runner is

derived primarily isometrically, so there is minimal change in muscle

length as well as minimal limb movement in creating force.

How does this equate to greater strength and less mass?

Let's assume that our runner is 150 lbs and hits the ground with 450

lbs of force against the mass of the earth. The earth is going to

return 450 lbs of force against the runner's mass. The runner's force

is not going to move the earth's mass but the earth's force is

certainly going to move the runner's mass since it is 3 times greater

than the mass of the runner. Now, up the ante with an elite sprinter

creating force equal to 5 x bodyweight and that sprinter is going to

be moving a lot further down the track. How can we know this? Because

Weyand's study showed that, " Average support forces of runners

applied to the running surface at top speed were systematically

higher for faster runners. "

(3) After digesting the above, it should be clear that strength

doesn't create ground reaction force, but rather accelerating mass

does. Ground reaction is just that, reaction to the force hitting it.

Since support force is largely isometric, joint actions are not the

prime points of focus for improvement. In addition, it should be very

clear from watching the video of the 2 runners that knee flexion is

minimal and therefore could not create the massive forces measured by

GRF plates. This goes back to the " test " I proposed to the members of

this forum.

(4) The deadlift is not better than its closest neighbor, the squat,

as far as maximizing strength, but it has some essential factors that

make it more efficient and effective for the training required. I'm

not

going to go into all those reasons. That being said, specific joint

action is not where strength is displayed for all of the reasons

stated above. Specificity of training for running is not centered

around joint movement but on increasing isometric strength, bone

density, muscle density, tendons etc. for increasing support force to

offset gravity. All of these are necessary as support and not the

creators of force. Ballistic lifts don't cut it here either.

(5) While the Pose method at least mentions gravity as relevant, it

barely touches on the importance of it. The system also relies on

training elements of running by means that simply don't work. I

passed on the Pose long ago.

It's quite simple to explain how vertical and horizontal influences

work together in sprinting (Interesting how that question is always

framed as how vertical can be responsible for horizontal. How about

we reverse the question: How does one get in the air by pure

horizontal forces?). The beginning of a run must be dominated by the

horizontal because it is necessary to use chemical muscle mechanical

work to overcome inertia by pushing the mass forward rather than

upward. As speed increases, the runner begins to elevate in order to

allow gravity to begin the work described above, that is, using the

force of gravity to create ground reaction force as well as creating

and storing elastic energy used for impulse in the vertical

direction. The vertical direction doesn't mean straight up, it means

that the runner will use a vector that allows them to trade the high

metabolic cost of chemical muscle mechanical work for the lower cost

of ground reaction force and effective impulse from elastic energy.

The horizontal force at take off is equal to the braking force at

touchdown, assuming no wind. This is true because of Newton's 3rd

law. The braking action is critical in maintaining the horizontal

portion of the vector. Here's why: The runner is traveling at a high

rate of speed while in air. At toe down, mass is just behind the

grounded foot. The foot stops moving forward at that point, but the

torso keeps moving horizontally, especially since the majority of the

mass is around hip height which creates a catapult-like effect. If

one drives a car at 25 miles per hour, but foolishly forgets to put

on a seat belt, what happens if the car hits a wall? The seatbeltless

person continues to move horizontally at the same speed the car was

moving until they hit something solid.

As mass crosses over the grounded foot, ground reaction force and

impulse from the elastic energy created from eccentric contraction

puts the runner back into their running vector. Ultimately, the

runner slows down as muscles tire from the isometric work and can no

longer create and release sufficient elastic energy.

(6) Your statement here was: " In relation to ground reaction forces,

you state that they are greatest halfway through the support stance

time and mostly gone after two-thirds of this time. "

In all due respect Dr. Yessis, this is what the measurements show and

there is no way to get around it. In fact, if you go back to

www.bearpowered.com/resources and click on Force Plate Fellow (circa

1970's or so and found on the internet), you will clearly see that a

ground reaction force plate only shows a measurement of force when

force is applied to it. It is also clear that merely crouching down

for the counter motion jump creates force because the body is

accelerating towards the plate (mass x acceleration=force). When the

man begins to move upward, force begins to disappear because he is no

longer accelerating downward. At the moment just before he lifts off

the ground, how much force is being applied to the ground? Virtually

no force is measured so there is virtually no force applied to the

ground when the jumper jumps. Isn't this where peak push off forces

should show if they exist?

In contrast, look at the 1 sec point where he begins toe down.

Within .2 seconds of toe down, force peaks, then starts to drop. This

is exactly what I described in (3) above. The answer to your

question, " How does this leave any force for the push-off? " is clear:

It doesn't leave any force for push off because there is no force

applied to the ground at push off. It also means that you're were

absolutely right when you say, " If this is true there is no need for

ankle extension. "

What you're seeing as ankle extension is caused by the reaction of

the previously grounded foot to the eccentric contraction of the calf

muscles and Achilles tendon as the man moves up from the counter

motion. The same reaction can be observed by pulling one forefinger

back as far as possible with the other forefinger, then releasing

it. It isn't chemical muscle power that snaps the just-released

finger forward, just as it isn't chemical muscle power that extends

the ankle at toe off. Pictures aren't proof of push off either

because they don't show force.

Proof that force is created at push off must be shown clearly on GRF

plates if that concept is to viable for training. Until that

proof is made available, exercises claiming to help create force at

push off should be set aside.

(7) I did not mean to imply that knee extension is the key factor in

supplying the speed in running. A small bend in the knee is necessary

to activate the spring part of the spring-mass model. A straight leg

would not allow for an effective spring action. It is the spring-like

action and GRF that supplies the speed in running.

Weyand truly understands running, as would his peers attest along

would the multiple citations of his work in the research papers of

others. Not one locomotion scientist has come forward to contend

against the research paper in the 6 years since publication of the

paper we've been discussing. Weyand's paper is ground breaking in its

analysis of running speed, mass-specific force, the effects of force

application, and much more.

And finally, there is always a danger in using pre-suppositional

thinking in order to review the merits of a " new " proposition. All of

us should be aware of that when we examine anything new, since we've

all been guilty of relying on something we thought to be true as the

bench mark for looking at the efficaciousness of a new approach. It

took 3 years for me to get through the fog of my pre-suppositions

regarding sprinting and sprint training before I could fully

understand the vast amount of research regarding the spring-mass

model and a strength training routine that fits within in the

trainable aspects of the model.>>>

***

Hello Barry

I've been out of town and apoloogize for the delay in responding.

Early in this discussion I mentioned the need to connect the dots

between the Weyand study and how it is applied. I'm sorry but I

must ask it again because your responses state many truths but not

how they fit into the discussion.

For example, in RE #1 there's nothing new here --- the information

is accurate but not the conclusion. More importantly it does not

address limb speed Speed of the body is dependant on limb speed and

the push-off. Simply compare a marathoner to a sprinter. Leg (limb)

speed is much different. This is pure physics, not opinion. The

formula for speed gives you the answer. Speed (more accurately

velocity) equals distance divided by time.

You go to great lengths talking about stride length and frequency

which are related to speed but not to the question asked. This only

clouds the issue.

RE #3 This is where a major problem exists. Yes a runner's body is

subject to gravity, but has little to do with it's speed. It plays

a minor role in comparison to the forces produced by the body.

For example, the vertical displacement of the CG in a sprinter is about 4

cm --about 1 inch. A free falling body dropping 1 inch cannot

generate the forces produced.

Your introduction of isometric force production is new and quite

intriguing as it may disprove what you have been saying. Do you mean

to say that when the foot hits the ground the limb muscles undergo

isometric " contraction " ? What happened to the eccentric and

concentric forces that are responsible for the spring model that you

previously espoused? Also note that the foot is in contact with the

ground for about one hundredth of a second, --certainly not enough

time to generate much isometric force.

Later on you state it is the support force that is isometric. This

is partially true but does it also provide the push-off force to

which you alluded earlier?

Your use of Newton's reaction law is also quite limited. By the way

you should know that I taught biomechanics for about 40 years and

am quite familiar with the laws and their application. Your

application of this law is flawed because you only consider the

vertical forces.

In # 6 you admit there are horizontal forces. Before it was only vertical, thus

my question on how it is converted to horizontal. These forces interact and

produce a reultant force, not two separate forces as you imply. And it can ONLY

be applied at push-off if Newton's law is to be in effect. But then you say it

is non-existent at pushoff since there are no vertical (I guess) forces at this

time. You still have not answered how the vertical is converted to horizontal

or if it is, how it is generated. This is the crux of this discussion and is

what must be addressed.

I need an explanation of the way you use braking force. How can it

be equal to horizontal force at take off? Sprinters minimize

braking forces as much as possible. Zero force is the best.

Also important at this time is to consider how the leg gets under

the body. Or since, in your view, what the legs do while airborne

is inconsequential why not have the runners land on the heel well in

front of the body, as many sprinters and even more marathoners do?

If we are to believe you, this would create even higher braking

forces which would then produce a stronger push-off.

Your last sentence in # 5 shows how you are erroneously concluding

the information that you have been presenting. We read that " ...the isometric

work (and) can no longer create and release elastic energy " . What happened to

the tendon-muscle complex and the spring model based on the eccentric-concentric

" contraction " ?

This is what I mean about sticking with the issues and not grabbing

bits of correct information and then trying to work them into a

seemingly scientific explanation.

RE # 6 I never challenged the force plate readings. I challenge the

way the data was interpreted and used by you or perhaps I should say

Weyand because you learned this from him. What has been lacking in

all the discussions is the horizontal component which most force

plate platforms do not record. But yet everything in your

discussion was explained by the vertical forces. This is what I

challenged and if someone truly understands running it should be

obvious that horizontal forces are much more important than the

vertical. And I don't refer to your use of horizontal when coming

out of the blocks. This has nothing to do with the issue at hand.

Being a track coach I'm surprised that you would not strongly

question the obvious lack of explanation for horizontal speed.

Simply asking yourself why sprinters use spikes should raise your

doubts about using this study and the many erroneous conclusions

that have been drawn from it.

You state (in # 6) that there is no force applied to the ground at

push off. This shows you do not believe--or understand-- that there

must be horizontal (with a vertical component) forces at takeoff.

If what you say is true you probably have the sprinters run without

spikes. Also I did not say ankle extension is not needed. As you may some day

learn it is a key force producing action.

I am not surprised that no one has challenged the results of Weyands

study. It takes a strong understanding of what constitutes running

from a biomechanical and kinesiological perspective,-- something

that to date I have not seen. As I mentioned earlier, you should

read my book, Explosive Running, for a full understanding -- at

least based on the latest sound, and not partial, information that

has been discussed.

You keep stating how Weyand truly understands running and how his

peers would attest. If this is so why do we not read some simple,

accurate, factual explanations of what occurs in the running stride?

Regards,

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

[Guest guest]

Have either of you (Dr Yessis/Barry) and used this information to

coach sprinters on the track and/or in the gym, and if so, how is

your information applied? I'm curious as to the application of the

technicalities brought forth in this debate.

[Mod: Do search the archives as both members have offered some wonderful

insights in the past. Additionally, it may be worth searching both respective

websites www.bearpowered.com and www.dryessis.com - much of the information is

available for free]

Cowell

Raleigh, NC

[Guest guest]

1. " Speed of the body is dependant on limb speed and

the push-off. …This is pure physics, not opinion. "

2. " You still have not answered how the vertical is

converted to horizontal or if it is, how it is

generated. This is the crux of this discussion and is

what must be addressed. "

3 " …if someone truly understands running it should be

obvious that horizontal forces are much more important

than the vertical. "

The preceding 3 statements by Dr. Yessis reflect his

continued rejection of the findings of the Weyand

study (statement 1) and the spring mass model used by

locomotion scientists worldwide (statements 2 and 3).

He is certainly free to express his opinion, but he

offers no independent scientific studies to support

it. He does cite his own book without reference to

any particular statement in the book. The book itself

contains no references to outside authorities or to

his own published studies. Instead, in his response

in this thread opinions are offered in the form of

statements like:

" Being a track coach I'm surprised that you would not

strongly question the obvious lack of explanation for

horizontal speed. "

There has been an explanation for horizontal speed,

Dr. Yessis just does not accept it. It is misleading

to continually assert that there is a lack of an

explanation when what is lacking is an acceptance of

the explanation. The spring mass model was beat to

death the last time around on this topic. Do we

really need to do this again?

Likewise, statements like, " If this is so why do we

not read some simple, accurate, factual explanations

of what occurs in the running stride? " are also

disingenuous. Factual explanations have been given.

Those who have disagreed have their own explanations,

but they have not produced independent studies backing

up their positions. They also generally ignore (or

reject) the models used by scientists to explain how

humans walk and run.

Finally, the statement " I am not surprised that no one

has challenged the results of Weyands study. It takes

a strong understanding of what constitutes running

from a biomechanical and kinesiological perspective,

-- something that to date I have not seen, " reflects

a rejection of contemporary locomotion studies and the

scientists who conducted them.

Now that we have established that Dr. Yessis disagrees

with Weyand and the other published locomotion

scientists and studies, can we move on? Further

discussion is not going to change anything.

Jon Haddan

Irvine, CA

[Guest guest]

> Hello Barry

>

> I've been out of town and apoloogize for the delay in responding.

>

> Early in this discussion I mentioned the need to connect the dots

> between the Weyand study and how it is applied. I'm sorry but I

> must ask it again because your responses state many truths but not

> how they fit into the discussion.

>

> Regards,

> ~~~~~~~~~~~~~~~~~~~~~~

> Yessis, Ph.D

> President, Sports Training, Inc.

> www.dryessis.com

>

> PO Box 460429

> Escondido, CA 92046

> ~~~~~~~~~~~~~~~~~~~

>

***

Thank you for your response, Dr. Yessis.

First, it's clear from your response that your analysis is based

primarily on kinematic study which, by its definition, does not

include any application of force (kinematics is defined as (1) the

branch of classical mechanics concerned with describing the motions

of objects without considering the factors that cause or affect the

motion or (2) a branch of physics that deals with the motion of a

body or system without reference to force and mass)

Among other things in your response to RE #1, you mention limb speed,

push-off, the formula for speed, and opinion. As I've mentioned

before, many of your responses are based upon pre-suppositional

analysis, which is quite common when it comes to speed training.

If we start with opinion, we must first note the title of Weyand's

study:

" Faster top running speeds are achieved with greater ground forces

not more rapid leg movements "

Obviously, the study was designed to address the very issue you've

presupposed; limb speed drives sprint speed. Weyand's study showed

that limb speed was not the main factor driving speed (although

presupposed by the majority) but instead, speed increase was derived

from increasing stride length at lower speeds and stride frequency at

higher speeds. Stride frequencies at higher speeds came from shorter

ground contact time and shorter swing time (time a given foot was not

on the ground). In fact measurements showed that swing times for

runners of varying speeds are similar. In the Weyand study the

difference in swing time between an 11m/s runner and a 6m/s runner

was 0.03 seconds.

It is your merely your opinion that Dr. Weyand's study has flaw,

creates misconceptions, or is not ground breaking.

Weyand's study is ground breaking as the first to test the validity

of limb speed as the cause of faster running. One can choose to

ignore the results and analysis, but this is not the case with

locomotion experts. Presuppositional belief, absent research data, is

an insufficient argument against the study.

You also presuppose the existence of push-off, based solely on

kinematic analysis, and the importance of the vertical. You state in

RE #3 that the sprinter only elevates 4 cm, but if the athlete

elevates at all, then one must assume the concept of push-off must

include a vertical element, and by extension, should show measurable

force at the point the push-off occurs. Since no force is measured

where push-off is alleged to occur, then one must assume one of the

following: (1) There is no vertical elevation by the runner; (2) The

amount of force is too small to be measured; (3) there is no push-off

and the vertical is caused by something else. You've admitted that

the athlete elevates, so #1 is eliminated. #2 would require enough

force against the ground to move the athlete's mass vertically. In my

previous post, I suggested that you look at Force Plate Fellow on my

website. It is clear from that video that force plates are able to

measure force when a person merely goes from an upright position to a

squat because their mass is accelerating downward. Certainly, if a

push against the plate was powerful enough to move the runners mass

upward (as you've stated that is does), it should register that force

application. Yet there is no force measured at the point of " push-

off. " Therefore, the only remaining option is #3 – there is no " push-

off " as you understand it.

Your response to RE #3 is inaccurate. To create the amount

of peak force measured is likely beyond human capability. As a

strength trainer since 1968, I know when the limits of human strength

approach, and clearly, that strength limit is far below peak forces

obtained by force plate measurements. Your response is inadequate as

well, because it is based on several fallacious assumptions:

First, measurements peak at 3 times bodyweight, or more, for

sprinters. The time frame from beginning to end of measured forces is

less than .04 seconds, beginning after the first 3rd of ground

contact time and ending prior to the first half of contact time.

Unless you have data provided by research to prove an alternative

time or duration, the question is how the measured amount of force

can be generated by human volition in such a short time frame. In my

38 years on the strength training side, I've never seen anyone

capable of moving that much weight that quickly in the weight room,

let alone over and over again while running. Of course my experience

is certainly anecdotal, but I've asked the question many times on many

forums, discussions, workshops, etc, without a single individual

stepping forward to say that it is possible to do move that amount of

weight one time let alone the number of times it would take to run

50m.

On another post on this site, Boardman stated, " …The

forces " generated " by pliometric impacts and running footfalls at top

speeds arise out of the energy conservation principles we have been

invoking in our simplified calculations. Impact forces compress or

extend (flex) the elastic tissues in question, the tissues compress

or elongate storing the energy in their electromagnetic force fields

and then they " reflex " ; returning the energy through a resistive

(restorative) force as they return to original position (dimension).

This is NOT a volitionally contractile procedure. (Emphasis by

Boardman) "

Despite Mr. Boardman's comments to the contrary, kinematic based

coaches continue to claim that the runner uses chemical muscle

mechanical force (volitional) to create the amount of force measured.

Second, you state, " …a runner's body is subject to gravity, but has

little to do with it's speed. For example, the vertical displacement

of the CG in a sprinter is about 4 cm --about 1 inch. A free falling

body dropping 1 inch cannot generate the forces produced. " There are

several possible deductions that could be made from your statement

including the following: (1) push-off exceeds the measured amount of

force occurring prior to mid-stance; (2) push-off occurs prior to mid-

stance; (3) force plate measurements are inaccurate; (4) the body is

not accelerating fast enough to produce the amount of force measured

(Force = M x A) from a 4 cm drop.

For the reason I stated earlier, it is not likely that, by human

volition, one would be able to move the amount of weight measured by

force plates within the time allotted. Therefore #1, in assuming an

even greater amount of force then what appears on force plates, is

not a viable deduction. # 2 is irrational according to the definition

of when push-off occurs. #3 is ludicrous. #4 has a few problems;

primary among them is that it's an inaccurate measurement. In

addition, it errantly presupposes that there is not enough time (in a

drop of 4 cm) to accelerate fast enough to create the amount of force

measured. This of course, ignores the top speed of a runner (which

could exceed 25 mph) contributing to the acceleration side of the

equation.

As a side note, our measurements, using software analysis, show that

a runner elevates more than 10cm (greater than 4 inches) rather than

your estimate of vertical displacement (4 cm or 1.5 inches (not the 1

in. you stated). This may not seem significant at first, but when

viewed in conjunction with rate of acceleration at high speed, it's

very significant

Regarding isometric contraction, there is no conflict with the spring-

mass model and eccentric contraction, since the eccentric contraction

is " forced " by the effect of the body landing at a high level of

force and that the stretch is increased as mass moves over the

grounded foot. There is only a conflict if one believes that the

force is chemically produced.

Dr. Yessis: clearly, your own statement in this section, " Also note

that the foot is in contact with the ground for about one hundredth

of a second, --certainly not enough time to generate much isometric

force, " disproves your own contention that measured force, or indeed

any force, is derived by chemical muscle mechanical force.

If isometric contractions, which create force significantly faster

than concentric contractions, are too short to generate much force in

the time you suggest, 0.01 seconds, how could the amount of measured

force be generated by concentric contractions within the time frame

you suggest?

In any case, the actual measured ground contact times are longer than

your conjecture, approximate 0.10s instead of 0.01s, still far short

of the time necessary to create force chemically.

I believe you misunderstood me, based upon this question, " Later on

you state it is the support force that is isometric. This is

partially true but does it also provide the push-off force to which

you alluded earlier? " since I did not allude to push-off as supplying

any force.

Finally, as pertains to RE #3 you believe that the application of

Newton's law in the research is flawed and that your knowledge of

biomechanics makes you familiar with its application. Just to set the

record straight, and without making a specific judgment towards you,

we both know that biomechanics is a core part of kinesiology, which

is the scientific study of human movement. This does not necessarily

provide expertise in all facets and applications of Newtonian

physics.

In RE # 5, you state that, " We read that " ...the isometric work (and)

can no longer create and release elastic energy " . What happened to

the tendon-muscle complex and the spring model based on the eccentric-

concentric " contraction " ? " The answer should be self evident since we

know that muscle don't run out of fuel when sprinting, as stated in

an article out of Rice University: " These findings complement what

scientists studying muscle fibers and cells have noted for some time:

Furiously contracting fibers do not run out of chemical energy.

Rather, muscles develop progressively less force with successive

contractions when they rely on anaerobic metabolism for chemical

energy. " In other words the muscles are no longer able to provide

the contractile power to run at high speed.

In RE # 6, I answered fully and clearly what creates the horizontal

direction. I'll repost it, in part, here:

-- It's quite simple to explain how vertical and horizontal

influences work together in sprinting (Interesting how that question

is always framed as how vertical can be responsible for horizontal.

How about we reverse the question: How does one get in the air by

pure horizontal forces?). The beginning of a run must be dominated by

the horizontal because it is necessary to use chemical muscle

mechanical work to overcome inertia by pushing the mass forward

rather than upward. As speed increases, the runner begins to elevate

in order to allow gravity to begin the work described above, that is,

using the force of gravity to create ground reaction force as well as

creating and storing elastic energy used for impulse in the vertical

direction. The vertical direction doesn't mean straight up, it means

that the runner will use a vector that allows them to trade the high

metabolic cost of chemical muscle mechanical work for the lower cost

of ground reaction force and effective impulse from elastic energy.

The horizontal force at take off is equal to the braking force at

touchdown, assuming no wind. This is true because of Newton's 3rd

law. The braking action is critical in maintaining the horizontal

portion of the vector. Here's why: The runner is traveling at a high

rate of speed while in air. At toe down, mass is just behind the

grounded foot. The foot stops moving forward at that point, but the

torso keeps moving horizontally.--

Clearly, I stated that the horizontal and vertical work together at

the beginning of the statement, so there is no implication, as you've

suggested, of them being separate.

Your statement, " And it can ONLY be applied at push-off if Newton's

law is to be in effect. But then you say it is non-existent at

pushoff since there are no vertical (I guess) forces at this time, "

There is no guessing here. There is no force measured

where you believe it occurs, and presupposition is leading you to

state that force can only be applied at push-off if Newton's law is

in effect. Newton's law is in effect when the accelerating mass of

the runner hits the ground and the ground returns that force equally,

independent of push-off.

Another presupposition in your approach becomes apparent when you ask

about braking force. When looking purely in the horizontal direction,

we must consider frictional force (also subject to Newton's 3rd law).

Without getting into the specifics of the coefficient of friction or

static vs kinetic friction... at the start of a run, the amount of

force applied horizontally to the surface will be matched by a return

force of equal amount from the surface as long as the surface

material allows it. This force creates the initial forward velocity,

which must include horizontal. At touch down, the amount of force

applied horizontally to create the runners forward velocity must be

equally matched by the force the ground would apply to the runner in

opposition to the runner's velocity. This is true for constant speed

running, without wind. As speed increases, there could be a slight

change to the above. Regardless, one must not forget that the foot

comes to a complete stop – no forward velocity, at touchdown. The

major portion of the runners mass above the grounded foot is still

moving horizontally as it rotates over the grounded foot. It does so

through inertia, not chemical muscle work.

To further deny horizontal dominance, as you see it, researchers

Munro, , and Fuglevand, in their 1987 study of ground reaction

forces in running, state that peak vertical forces are 5-10 times

peak horizontal forces.

Your statement in regard to braking, " Zero force is the best " is,

again, based on your presupposition that, " Sprinters minimize braking

forces as much as possible. " That is what you teach, based upon your

view of sprinting. I've seen no studies that suggest what you say is

correct, but I've seen a significant amount of material by others in

agreement with what you state. However, in every case, they rely on

kinematic evidence that fails to provide complete understanding of

what affects running.

Several times you've either misapplied what I wrote. For instance, " Or since, in

your view, what the legs do while airborne is inconsequential why not have the

runners land on the heel well in front of the body, as many sprinters and even

more marathoners do? If we are to believe you, this would create even higher

braking forces which would then produce a stronger push-off " does not

necessarily follow from what I said. In fact, it's typical that those who

believe in " running form " as a necessary part of coaching fail to understand the

most prevalent cause of overstriding – the lack of air time to swing the leg

around to the point where is can land closer to the center of mass. This lack of

air time is caused by insufficient mass-specific force and/or insufficient

release of elastic energy. Both are easily corrected in the weight room without

spending any time on " form " .

Dr Yessis, you said, " What has been lacking in all the discussions is

the horizontal component which most force plate platforms do not

record. But yet everything in your discussion was explained by the

vertical forces. This is what I challenged and if someone truly

understands running it should be obvious that horizontal forces are

much more important than the vertical. And I don't refer to your use

of horizontal when coming out of the blocks. This has nothing to do

with the issue at hand. "

This is another error you've made, among the ones noted above.

You state that, " What has been lacking in all the discussions is the

horizontal component which most force plate platforms do not

record. " In fact, the ground reaction force plate used by Weyand was

similar to what was described by Kram, et al., in a research

paper out of U. C. Berkeley, in 1998.

The document was titled, " Force treadmill for measuring vertical and

horizontal ground reaction forces, (jap. Appl. Physiol. 85(2): 764–

769, 1998. " Contrary to your comment, the opening statement, " We

constructed a force treadmill to measure the vertical, horizontal and

lateral components of the ground-reaction forces (Fz, Fy, Fx,

respectively) and the ground-reaction force moments (Mz, My, Mx),

respectively exerted by walking and running humans, " assures the

reader that horizontal forces could, and were, considered where

applicable in the study.

What one truly needs to understand is vertical forces and how they

relate to running since the horizontal has minimal impact on running

speed. The " horizontal " aspect is the mantra of all those who've

developed their own brand of " form " training based solely and often,

errantly, on kinematic studies.

As a track coach, I'm surprised, at times, that anyone questions the

dominance of the vertical over the horizontal, but then I also

believed, previously, that sprinting was based primarily on the

horizontal and that it relied on chemical mechanical muscle work to

accomplish force production. Since then, I've come along far enough

not to read any materials that purport to instruct the reader on how

to run faster, or train others to run faster, without a clear and

true presentation of how measured ground reaction force are derived.

Finally, you have made numerous comments that intimate that my

associates and I are somehow misinformed, and therefore are below

your level of knowledge. If you find legitimate errors regarding

facts in what we present, then tell us so that we can either correct

our understanding or present what we believe to be correct in a

better way. As to what you believe on the different aspects of

running and training runners, I can assure you that we understand

your position completely; we simply don't agree with it because it

does not properly portray the effects of gravity and mass-specific

force in opposition to gravity.

Regards,

Barry Ross

Los Angeles, Ca.

[Guest guest]

<<<Have either of you (Dr Yessis/Barry) and used this information to

coach sprinters on the track and/or in the gym, and if so, how is

your information applied? I'm curious as to the application of the

technicalities brought forth in this debate.>>>

***

In regard to your questions the exercises and training program

described in Explosive Running have been used by runners on all

levels especially from high school through the Olympic and world

class level. Most significant is that the runners improve their

speed without doing additional running. In many cases, they

actually do less running. If you use the exewrcieses as described

you will find your runners improving significantly and constantly.

This occurs with or without a running coasch. The results are not

temporary, they are significant and improve every year.

Whichever program you decide to use, for verification I would

recommend that you be influenced mainly by proven results. They

should be substantiated as for example the differences from when

the athlete first starts and after 6 months, 1 year etc. Many

coaches take credit for athletes who were already great when they

got them but never improved. The coach takes credit for their

development when in reality he did no development.

I hope this helps.

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

[Guest guest]

> ***

> If you had read my book you would not say that I don't understand

or don't' agree with the spring model. You would find out that in my

books I use it to explain many of the actions that occur in jumping

and only partially in running which relies more on the stretch

reflex. There is a distinct difference between the two.

>

> In regard to the spring model or more importantly development of

> energy return and muscle reislancy, if you read the US track

> coaches journal you would see that I have defended this position

> against the medical profession and other coaches who believe that

> plyometrics and explosive training was highly dangerous.

>

> In fact, if you are well versed in the literature, you would have

> read many of my articles not only in sports related magazines but

> also in fitness magazines in which I describe the stretch reflex and

> its consequences and how it should be used in training.

>

> In addition, if you read some of my early articles in which I was

> introducing the works of Verkhoshansky and other Russan

> scientists/coaches you would have read many explanations of the

> spring model/stretch reflex. If you're familiar with Verkhoshansky's

> work with Soviet world record holders and Olympic champions you

> would see how I was a stauch supporter of getting this information

> (especially plyometrics which may well still have been a " secret " )

> out to US coaches.

>

> Its also interesting to note that in my book, Explosive Running the

> exercises that I created coincide and show great similarity to those

> outlined by Verkhoshansky in Specialized Strength Training for

> Coaches. This is not surprising since even he has stated that I am

> one of the few Americans that truly understands not only the Soviet

> system of training athletes but the bases for many of their

> exercises and training methods.

>

> The training methods in his book are far removed from any of the

> conclusions drawn by the Weyand study and its' supporters. To date

> no one has been able to state in specific terms how the findings

> from this study are applied. Perhaps you would be kind enough to do

> this for us. Also if you read my posts carefully you would know that

> I never questioned Weyand's findings. I have and still do question

> the interretations that have been drawn from the study. This is

> the core of the problem.

>

> Reading from you and others, the implication is that the Weyand

> study is a ground breaking study and one of the greatest things

> that ever happened in the advancement of running. It reminds me of

> Arthur when he discovered the key element involved in

> strength. He wasn't been able to identify it, but it took 20 ages

> or so to talk about its existance.

>

> You're correct in saying that this discussion is going no place

> because no one has answered my questions. Instead we have been

> treated to educational theses related to the topic but not

> answering the pertinent questions.

>

> One last thought. Since you seem so intrigued with references, its

> curious to me why you think a book written for coaches and serious

> runners should be judged by references. If you are a track coach I

> challenge you to name the most popular track books that have

> references for what they recommend. Do you not read these books?

***

I'm in agreement with both Jon Haddan and Ken Jakalski that

continuing this discussion with Dr. Yessis is not going to produce

much in the way of agreement between us.

I would like to make it clear however that a significant amount of

proof and explanation was provided for Dr. Yessis, and others

following this thread, to review.

Dr. Yessis, you certainly have the right to question the information

we've provided concerning high speed running and the training

protocols we've suggested to enhance running speed. You also have the

right to accept or reject answers you receive as either valid or

invalid.

As for Weyand, when adding the large body of locomotion experts who

agree with or cite Weyand's work in their own research papers to the

30 citations of other research papers (from dozens of different

researchers) which formed the foundatation of the Weyand paper we've

been discussing, it's easy to see why he should be accepted as an

expert in the field.

For the reasons above, you're book should neither stand as a primary,

scientifically based rebuttal to Weyand's research in particular, nor

to the larger body of locomotion experts who agree with or cite

Weyand's work.

We've made statements as to why we cannot accept much of the material

in your book. Specifically, why force plate measurements do not fit

within the parameters of what you suggest in your book and how the

amount of measured forces can be so much greater than any runner is

able to produce through chemical muscle mechanical work over the

duration of any sprint distance. Weyand's study offers rational

causes for both, while, so far, neither you nor your book has offered

any explantion at all. It's extremely difficult, if not impossible,

for us to ignore something that exists, is measurable and must have a

cause without a viable and rational explanation as to why it should

be ignored.

As a final point, it should be made crystal clear that we also

believed what you and your book and your articles promote. When we

failed to get answers from others to some of the questions we've

posed to you (also without answers), we were troubled, then we

searched.

Thanks to Weyand and his associates, we found scientifically based

answers to our questions, from which we could design workout

protocols that address specifically what needs to be trained.

With that, I'll sign off of this thread.

Barry Ross

Los Angeles, CA

[Guest guest]

" I stand by my comments regarding the mass-spring

model concept. What you [barry Ross]don't understand

that this model is used to explain what happens in

jumping . It is sometimes used to explain a very

small part of running. And then, only for a

comparison. "

**

That statement is inaccurate and your previous

statement that horizontal forces are much more

important than vertical forces in running simply does

not match up with the model that you now claim to

support. Perhaps you could actually quote from your

book where you state that the spring mass model is the

generally accepted explanation for how humans run.

I don't see the relationship between your having

introduced the works of Verkhoshansky or been an early

advocate of plyometrics and the topic at hand. I also

don't see what the similarity in exercises between

your book and his has to do with the topic or what it

is supposed to mean.

If, as you say, you are one of the few Americans that

truly understands the Soviet training system, fine.

What does that have to do with the Weyand study?

The fact that Verkhoshansky's training methods are

" far removed from any of the conclusions drawn by the

Weyand study and its' supporters " does not mean

anything except that the supporters of the Weyand

study do not follow such methods. But,

you keep stating that no one has been able to " state

in specific terms how the findings from this study are

applied. " Didn't you just imply that the supporters

must be using different training methods than

Vekhoshansky? How else do you conclude that his

methods are far removed from their conclusions? Or

are you suggesting that the supporters who have drawn

conclusions far removed from Verkhoshansky's training

methods are nonetheless still using those methods?

Could you please explain your statement " if you read

my posts carefully you would know that I never

questioned Weyand's findings " in light of your

statement " Speed of the body is dependant on limb

speed and the push-off. …This is pure physics, not

opinion " and the title to Weyand's study " Faster Top

Running Speeds are Achieved with Greater Ground Forces

not More Rapid Leg Movements "

If as you claim it is the interpretations not the

findings that you disagree with then what is it about

the interpretations of Weyand's study that you

actually disagree with?

You state, " Reading from you and others, the

implication is that the Weyand study is a ground

breaking study and one of the greatest things that

ever happened in the advancement of running. " I

certainly never made any such statements. However, if

you do not disagree with the study (as you say) and it

is not ground breaking, then it must be old news.

What about it is old news?

Your comparison of the Weyand study to Arthur is

off the mark. designed a product and came up

with studies to support its marketing. Weyand is a

research scientist. No similarities at all.

You know full well that certain people are applying

the findings (which you claim you agree with) by

limiting their lifting to one basic lift (far removed

from Verkhoshansky's training methods), and largely

ignoring issues of form (which is heavily emphasized

in your book).

I did not state that a book written for coaches and

runners (your characterization of your own book)

should necessarily be judged by a lack of references.

I was not judging your book in the context of its

originally intended audience, but in the manner in

which you have currently been using it. A book

without references is really just one person's

opinions. It should not be cited by the same person

who wrote it as the sole authority for rejecting a

published study or its interpretations. Having given

your opinion, which you are certainly free to do.

Since you asked about track books with references, let

me suggest to you Better Training for Distance

Runners " by E. Marin & N. Coe or

the Jess Jarver series. If you want a general

training book with references, how about

Supertraining. The Lore of Running is another book

heavily footnoted. s Running Formula is based

on a lot of research. My recollection is that Irv Ray

& Tony Benson's book cites the work of Jack s

and others. All of these books are well known by

people in track circles. Whether they are the most

popular I couldn't say. Barry Ross wrote a book that,

as I recall, references numerous studies.

Jon Haddan

Irvine, CA

[Guest guest]

>

> You're correct in saying that this discussion is going no place

> because no one has answered my questions.

***

Dear readers,

I really like to read the ST posts, since multiple experts are together

here. We have people with different opinions in this discussion. I

would really like that we continue the discussion and stop insult-type

like arguments, let's try to face the facts and give the opinion of the

other a chance.

Dr Yessis states that no one answered his questions yet. I have traced

back his questions from his post on 28/10. In total there were 7

questions. I tried to collect the responses of Mr Ross and placed them

under the questions of Dr Yessis of 28/10 (see below). I also added

some questions that might help the discussion.

I would like to invite Dr Yessis to state exactly for which questions

(i.e. numbers) he did not receive an answer. Then we can continue the

discussion on contents rather than emotion.

Many thanks in advance to Dr Yessis.

Stefan IJmker

Haarlem, the Netherlands

28/10 Questions Yessis

1) First, since limb speed TIME, is basically the same between

fast and slow runners, why do you say that SPEED of movement is not

important? Does not the faster runner cover more ground? If time

is the same, speed of movement must be faster to complete the same

limb movement. It appears to me this is simple physics.

Put another way, if one runner has a stride length of nine feet, and

another six feet, can limb speed be the same for both runners?

Ross(30/10): yes, if ground contact time is shorter.

Yessis (9/11): Speed of the body is dependant on limb speed and

the push-off. (Limb) Speed (more accurately velocity) equals distance

divided by time.

Ross (11/11): (referring to the Weyand study): speed increase was

derived

from increasing stride length at lower speeds and stride frequency at

higher speeds. Stride frequencies at higher speeds came from shorter

ground contact time and shorter swing time (time a given foot was not

on the ground). In fact measurements showed that swing times for

runners of varying speeds are similar.

Question to Dr Yessis: you state the faster runner covers more ground

and thus have higher limb speed. Is this distance component during

ground contact only or during (ground contact + air time)? Can limb

speed be the same if ground contact time is shorter and (therefore)

distance covered during ground contact is the same?

2) Second, your concept of mass-specific support force is

intriguing. In physics, mass times acceleration produces force.

This means that the more you increase either or both of these

qualities, the more you increase force. If the study found that

ground support force is the key to speed, how does this then equate

to greater strength and less mass? This is especially pertinent

when the trend in the last decade or so has been on heavier and

" bulkier " sprinters.

Ross(30/10): during running the direction of the falling body should be

reversed during ground contact. If the ratio between strength and mass

can be increased (more force per kg bodyweight) reverse the direction

of the body in vertical direction (transforming a negative vertical

acceleration to a positive vertical acceleration).

Question to Dr Yessis: If you get stronger and heavier in the same

ratio, i.e. relative strength stays the same, would you expect that you

will run faster (all other things being equal)?

3) If strength is the key how will the strength be used to create

ground reaction forces? Which joint action(s) are you trying to

improve so that they will create more support force?

Ross 30/10: ground reaction forces are a result of the falling body,

not of muscle strength.

Yessis (9/11): a free falling body during sprinting cannot generate the

forces produced.

Ross 11/11: The top speed of a runner (which

could exceed 25 mph) contributes to the acceleration side of the

equation.

Question to Dr. Yessis: What is your opinion of the cause of the ground

reaction forces?

4) Ken went to great lengths talking about the deadlift exercise

that you recommended. Why this exercise? What does it help to do

to create more force? How? As I believe you understand, strength

must be displayed in a specific joint action if it is to be used in

running. This is what specificity of training is all about.

Ross 30/10: specific joint action is not where strength is displayed

for all of the reasons

stated above. Specificity of training for running is not centered

around joint movement but on increasing isometric strength, bone

density, muscle density, tendons etc. for increasing support force to

offset gravity. The deadlift is supposed to do this.

5) In your book you state that the most important finding of the

Weyand study was that VERTICAL ground reaction forces were the most

important in running speed. Perhaps you can explain how vertical

forces are responsible for horizontal movement speed. You must

agree with the POSE people who state that they have found a way to

take vertical forces and convert them to horizontal. If you, too,

have found how to do this, you have found a way to revolutionize

sport.

Ross 30/10: horizontal and vertical forces work together. Release of

elastic energy is the driving force for vertical and horizontal

acceleration.

Yessis 9/11: does the isometric support force also provides the push-

off force?

Yessis 9/11: the resultant horizontal and vertical force can only be

applied at push-off if Newton's law is in effect. How is the vertical

force converted in the horizontal force? I need an explanation of the

way you use braking force. How can it be equal to to horizontal force

at take off?

Yessis 9/11: what happened to the tendon muscle-complex and the spring

model based on eccentric-concentric " contraction " ?

Ross (11/11): Regarding isometric contraction, there is no conflict

with the spring-

mass model and eccentric contraction, since the eccentric contraction

is " forced " by the effect of the body landing at a high level of

force and that the stretch is increased as mass moves over the

grounded foot. There is only a conflict if one believes that the

force is chemically produced….

The vertical direction doesn't mean straight up, it means

that the runner will use a vector that allows them to trade the high

metabolic cost of chemical muscle mechanical work for the lower cost

of ground reaction force and effective impulse from elastic energy….

one must not forget that the foot comes to a complete stop – no forward

velocity, at touchdown. The major portion of the runners mass above the

grounded foot is still moving horizontally as it rotates over the

grounded foot. It does so

through inertia, not chemical muscle work.

Question to Dr Yessis by Dr Ross 11/11: If isometric contractions,

which create force significantly faster than concentric contractions,

are too short to generate much force in the time you suggest, 0.01

seconds, how could the amount of measured force be generated by

concentric contractions within the time frame

you suggest?

Question to Dr Yessis: Is eccentric-concentric contracting happening

during running? How does this relate to muscle activation patterns and

ground reaction forces measured during constant speed running?

6) In relation to ground reaction forces, you state that they are

greatest halfway through the support stance time and mostly gone

after two-thirds of this time. How does this leave any force for

the push-off? If this is true there is no need for ankle extension.

Ross 30/10: There is no push-off through ankle extension, because

ground reaction force measurements do not relevant forces at toe-off.

Ankle extension is a result of the eccentric contraction during mid

stance.

Yessis 9/11: horizontal forces during running are far more important

than vertical forces. There must be horizontal (with a vertical

component) forces at takeoff (therefore spikes are needed). Ankle

extension is a key force producing action.

Ross 11/11: To further deny horizontal dominance, as you see it,

researchers

Munro, , and Fuglevand, in their 1987 study of ground reaction

forces in running, state that peak vertical forces are 5-10 times

peak horizontal forces…..

no force is measured (by ground force plate) where push-off is alleged

to occur…. (Vertical force) measurements peak at 3 times bodyweight, or

more, forsprinters. The time frame from beginning to end of measured

forces is

less than .04 seconds, beginning after the first 3rd of ground

contact time and ending prior to the first half of contact time.

Unless you have data provided by research to prove an alternative

time or duration, the question is how the measured amount of force

can be generated by human volition in such a short time frame…..

Question to Dr Yessis: Do you think that ankle extension is important,

and if so, what proof is available for this causing acceleration of the

body?

7) Tied into this, it should be noted that in your discussion of

strength exercises, you imply that knee extension is the key factor

supplying the speed in running. ( your #2). But if you look at the

sequence pictures in Explosive Running or of any sequence pictures

of high-level runners, you will see that the knee remains bent

during the push-off. It does not straighten. Thus, where does the

force for forward running speed come from?

Ross 30/10: Knee extension is not per se the main factor, spring like

behaviour (of muscles) and ground reaction force cause forward running

speed. A bent knee is needed for optimal storage and release of elastic

energy.

Question to Dr Yessis: In your opinion, is it possible that the release

of elastic energy can restore forward speed of the body [during

constant running speed]?

[Guest guest]

I did not read anything into your comments. I quoted

you directly, pointed out that you continually view

the spring mass model as a description of jumping, not

running, and asked you specific questions about your

own words.

Your constant reference to plyometrics and

Verkhoshansky's work simply misses the point as to

what the spring mass model is used to describe.

Familiarity with a Russian coach's training protocol

involving depth jumps or the history of the term

plyometrics is not necessary to be able to properly

label the spring mass model as the generally accepted

model used by locomotion experts today to describe how

humans RUN. Whatever your involvement was with Fred

Wit 31 years ago, it has little to do with the fact

that you continue to mischaracterize what the spring

mass model is used to describe today.

Your claim that you have never challenged the findings

of Weyand's study is not accurate. Previously, you

questioned the swing data claiming he had not taken

into account the limb speed. You did this apparently

not realizing the two are different. You state in

your latest post that if people understood the works

of Verkhoshansky then they would " understand why I

have criticised some of the conclusions by Weyand and

others. " Based on your response to my last set of

questions, I assume it is impossible for you to

explain what it is in Vekhoshansky's works that cause

you to criticize some of the conclusions by Weyand, or

to identify what conclusions you criticize.

Immediately following that sentence you state, " I must

also once again remind you and others that I never

challenged the findings of his study. " So you haven't

challenged the findings, just criticized the

conclusions. In the context of the discussions on

this topic, that is a very fine line indeed. The

finding that faster runners generate more power than

slower runners but recycle their legs at approximately

the same speed is acceptable, but the conclusion that

faster runners run faster by generating more power

than slower runners and not by recycling their legs

faster is not. Is that your position? Then what

accounts for their faster speed?

Like others before me, I am now finished with this

thread. The issues you have raised have been clearly

answered and /or refuted. If you choose to ignore the

evidence presented and stick with whatever belief

system you have that is your right. The rest of us

have moved on.

Jon Haddan

Irvine, CA

[Guest guest]

Stefan IJmker wrote:

<<<I really like to read the ST posts, since multiple experts are

together

here. We have people with different opinions in this discussion. I

would really like that we continue the discussion and stop insult-

type

like arguments, let's try to face the facts and give the opinion of

the

other a chance.

Dr Yessis states that no one answered his questions yet. I have

traced

back his questions from his post on 28/10. In total there were 7

questions. I tried to collect the responses of Mr Ross and placed

them

under the questions of Dr Yessis of 28/10 (see below). I also added

some questions that might help the discussion.

I would like to invite Dr Yessis to state exactly for which questions

(i.e. numbers) he did not receive an answer. Then we can continue the

discussion on contents rather than emotion.

Many thanks in advance to Dr Yessis.>>>

***

Stefan -- Yes I am willing to address your questions but only with

the stipulation that we stick with the issue at hand and not go

off on a tangent. This will become clearer as I respond. Also a

few comments to clarify some points and to set some ground rules.

First, I have no problem with, nor have I argued against the

findings of Weyand or other researchers. My concern has been with

the conclusions, interpretations, etc. Thus the discussion should

revolove around this latter point.

Second, I make a distinction between a response, which the

respondents have done, and an answer to a specific point. In my

opinion the responses only tended to confuse rather than enlighten

the isssue. This should be become clearer if we proceed.

Third, rather than answering all your questions or responding to all

your points at one time I believe it is necessary to examine only

one or two at one time. In the process it may answer other

questions. This will keep us better focused.

If this acceptable to all parties (who will have to again respond to

some of my questions or answers) I am willing to do as requested.

Once I hear back from you I will address the first point raised.

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

[Guest guest]

" I stand by my comments regarding the mass-spring

model concept. What you [barry Ross]don't understand

that this model is used to explain what happens in

jumping . It is sometimes used to explain a very

small part of running. And then, only for a

comparison. "

***

I do understand the spring-mass concept.

Your statement above, that the model is used to explain jumping and

that it is sometimes used to explain a very small part of running

provides significant proof as to why your analysis of running is

inaccurate.

The following is an appreviated number of research documents that

categorically deny your understanding of the spring-mass model being

primarily for jumping and little for running:

-- " Do muscles function as adaptable locomotor springs? "

Stan L. Lindstedt, Trude E. Reich, Keim and C. LaStayo

---This cyclic `stretch—shorten' use of muscles during locomotion

occurs at a predictable body-size-dependent frequency such that a

running animal behaves like a simple spring mass system (Farley et

al., 1993)---

-- " Running in the real world: adjusting leg stiffness for different

surfaces "

P. Ferris*, Micky Louie and T. Farley

---In fact, the simplest model of a running animal is a spring-mass

system consisting of a linear spring representing the stance limb

(i.e. the leg spring) and a point mass equivalent to body mass

(Blickhan 1989; McMahon & Cheng 1990)---

-- " The spring-mass model and the energy cost of treadmill running. "

Dalleau, G., A. Belli, M. Bourdin, and J.-R. Lacour. Eur. J. Appl.

Physiol. 77: 257–263, 1998.

-- " The effect of speed on leg stiffness and joint kinetics in human

running "

Adamantios Arampatzis*, Gert- BruK ggemann, Verena Metzler

Accepted 14 June 1999

---The goals of this study were to examine the following hypotheses:

(a) there is a difference between the theoretically calculated

(McMahon and Cheng, 1990) and the kinematically measured length

changes of the spring-mass model and ( the leg spring stiffness,

the ankle spring stiffness and the knee spring stiffness are

influenced by running speed.---

-- " Swing-leg retraction: a simple control model for stable running "

André Seyfarth, Hartmut Geyer and Hugh Herr

Boston, MA 02114, USA

Accepted 22 February 2003

---SINCE ITS FORMULATION, THE SPRING-MASS MODEL HAS SERVED AS THE

BASIS FOR THEORETICAL TRATMENTS FO THE ANIMAL AND HUMAN RUNNING, NOT

ONLY FOR THE STUDY OF RUNNING MECHANICS, BUT ALSO STABILITY.

The results of this study indicate that swing-leg retraction

significantly improves the stability of spring-mass running,

suggesting that swing-phase limb dynamics may play an important role

in the stabilization of running animals.

For the contact phase of symmetric running gaits, researchers have

described the dynamics of the center of mass with a spring-mass model

comprising a point mass attached to a massless, linear leg spring

(Blickhan, 1989; McMahon and Cheng, 1990).---

-- " A movement criterion for running "

Andre Seyfartha,b,*, Hartmut Geyera,b, G.unthera, Reinhard

Blickhana

---The adjustment of the leg during running was addressed using a

spring-mass model with a fixed landing angle of attack.---

-- " A collisional model of the energetic cost of support work

qualitatively explains leg sequencing in walking and galloping,

pseudo-elastic leg behavior in running and the walk-to-run transition "

Andy Ruina, E.A. Bertram, Manoj Srinivasan

This draft: March 24, 2005

---A popular observation is that human legs behave much like springs

while running (e.g, , 1990, Blickhan, 1989, Farley and

, 1996, McMahon, 1985). That is, a spring-mass model captures

much about the ground forces and center-of mass motion in running.---

-- " RUNNING SPRINGS: SPEED AND ANIMAL SIZE "

CLAIRE T. FARLEY, JAMES GLASHEEN AND THOMAS A. MCMAHON

Cambridge, MA 02138, USA

Accepted 20 July 1993

---We examine how the musculoskeletal spring system operates at

different speeds and in animals of different sizes. We model trotting

and hopping as a simple spring-mass system which consists of a leg

spring and a mass. " ---

Your questions regarding the horizontal direction of locomotion and

it's importance are also suspect.

A study published in 1999, THE INDEPENDENT EFFECTS OF GRAVITY AND

INERTIA ON RUNNING MECHANICS

YOUNG-HUI CHANG*, HSUAN-WEN CATHY HUANG, CHRIS M. HAMERSKI AND RODGER

KRAM

Accepted 15 October; published on 22 December 1999, states the

following:

Surprisingly, gravity also affected the horizontal impulses

generated against the ground to brake and accelerate the runner

with each step. With a 30 % increase in gravitational and

inertial force (+GF+IF), there was a 28 % increase in the

horizontal impulses generated against the ground. In contrast,

with a 30 % increase in inertial force (+IF) alone, there was

only an approximately 10 % increase in horizontal impulses.

By deduction, our data indicate that the difference in the

horizontal impulses between the two treatments (approximately 18 %)

is due solely to gravity. Furthermore, with a 75 % reduction in only

gravitational force (-GF), there was a 53 % decrease in horizontal

impulse. A related phenomenon was actually seen by W. O. Fenn as

early as 1930. Fenn (1930) observed a coupling between vertical and

horizontal forces with changes in forward running speed.

CONTRARY TO OUR ORIGINAL HYPOTHESIS AND INTUITION, these data

indicate that gravity affects not only the generation of active

vertical forces but also indirectly affects the generation of

horizontal forces. GRAVITY(rather than inertia) APPEARS TO EXERT THE

MAJOR INFLUENCE OVER BOTH VERTICAL AND HORIZONTAL FORCE GENERATION

DURING RUNNING. (emphasis is mine)

The sum of this, Dr. Yessis, is that hypothesis and intuition rather

then science and research continues to drive much of the

understanding of how we run, and by extension, training.

Show us research.

Barry Ross

Los Angeles, CA

[Guest guest]

> Hello Dr Yessis, yes this is acceptable and exactly what I would

> like. So no emotional argumenting, only facts, asking for

> clarification, showing research findings which contradict/support

the

> points raised. And last of all stick to the points raised. Let's go

> to them one by one.

>

> I will place the first one underneath:

>

>

> Yessis (28/10):

> 1) First, since limb speed TIME, is basically the same between

> fast and slow runners, why do you say that SPEED of movement is not

> important? Does not the faster runner cover more ground? If time

> is the same, speed of movement must be faster to complete the same

> limb movement. It appears to me this is simple physics.

>

> Put another way, if one runner has a stride length of nine feet,

and

> another six feet, can limb speed be the same for both runners?

>

> Ross(30/10): yes, if ground contact time is shorter.

>

> Yessis (9/11): Speed of the body is dependant on limb speed and

> the push-off. (Limb) Speed (more accurately velocity) equals

distance

> divided by time.

>

> Ross (11/11): (referring to the Weyand study): speed increase was

> derived

> from increasing stride length at lower speeds and stride frequency

at

> higher speeds. Stride frequencies at higher speeds came from

shorter

> ground contact time and shorter swing time (time a given foot was

not

> on the ground). In fact measurements showed that swing times for

> runners of varying speeds are similar.

>

> Question to Dr Yessis: you state the faster runner covers more

ground

> and thus have higher limb speed. Is this distance component during

> ground contact only or during (ground contact + air time)? Can limb

> speed be the same if ground contact time is shorter and (therefore)

> distance covered during ground contact is the same?

>

> Many thanks in advance for your response

****

My response

Perhaps my statements and question were not sufficiently clear but

they were related to limb speed, not running speed. As should be

well recognized, when dealing with a specific point the other

factors (variables) remain constant. If not we can never answer a

specific point. Thus my question is: if time of executiong the limb

movements is basically the same, but one runmner covers greater

distance with his limbs, can speed of limb movement be the same?

Once this question is answered we can discuss ground contact time,

or beter yet ground forces.

*******

Stefan

Were you able to get the data that I requested regarding ground

forces during the support phase?

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

[Guest guest]

>

>

> >if time of executiong the limb

> > movements is basically the same, but one runmner covers greater

> > distance with his limbs, can speed of limb movement be the same?

>

> Stefan's response

>

> In the example you stated, limb movement would be faster for the

> person covering greater distance with his limbs.

>

> This brings me to a question though: what does the above mean for

> sprinting/fast running? And possible for (technigue) training? My

> ideas are getting more and more clouded.

>

> In my opinion Weyand also states something relevant to this issue.

In

> my opinion greater distance traveled by the limbs should be

> accompanied by greater distance covered during ground contact

(please

> correct me If I am wrong in your opinion):

>

> We found little difference in the third mechanism

> that would enable faster runners to reach faster top

> speeds: increasing the forward distance traveled during

> the stance period or contact lengths. Our regression

> equation indicated that contact lengths were 1.10

> times greater for a runner with a top speed of 11.1 vs.

> 6.2 m/s. However, this resulted from a gender difference

> in top speed: our female subjects generally had

> shorter legs, shorter contact lengths, and slower top

> speeds. Within groups of male and female runners,

> contact lengths varied little or not at all in relation to

> top speed. Although elongated steps would provide a

> speed advantage by increasing the time available to

> apply ground force, runners do not exercise this option

> because unnaturally long steps compromise the ability

> of the active muscles to apply the ground force necessary

> to elevate the body for the ensuing step. By worsening

> the mechanical advantage and disrupting the

> natural spring-like behavior of the leg (8), unnaturally

> elongated steps increase the muscle forces and volumes

> that must be recruited per unit of force applied to the

> ground (22). Reductions in the ground force applied in

> relation to the muscle forces generated would directly

> reduce maximum ground forces and therefore also reduce

> top running speeds.

>

>

> > Stefan

> >

> > Were you able to get the data that I requested regarding ground

> > forces during the support phase?

> >

> Mr Yessis: to my knowledge this info is in the pictures I

uploaded,

> see the files section (ground reaction force pictures), take the

zip

> files (the newer ones). Foot position is marked as well as upper

body

> position. It is qualitative data at best, but I have no better

data

> at the moment.

>

> Please state which data you are missing (if any), then I can

search

> for them. In the literature very few data have been published on

> pictures relating body angles and vertical ground reaction force

> profile. Maybe ST readers can help if needed.

>

> Looking forward to your reply, thanks for putting effort in

> responding.

***

You are getting ahead of what I proposed -- one topic at a time.

The question of limb speed has not been answered by Barry and others

who maintsin that limb speed is not important or is the same in

better runners. We first need an answer from them to determine if

their conclusions are accurate or warranted by the Weyand study.

If I am going to continue in this discussion in which I stated and

will restate that their conclusions are incorrect they have to

answer my queries, not just reply to them.

(1)Thus I will not at this time address your question. When I do

however, we will need to define some terms. What do the authors

mean by overstriding? Has anyone ever seen this on live video with

an accomplished runner? ( I don't mean staged, I mean in a real

race) Is there any data to support the notion of overstriding in

sprinters? marathoners?

(2)In regard to distance traveled by the leg during support, have

you read my book Explosive Running? It may help you better

understand this and many other points being raised.

(3) In regard to ground forces, we need the actual forces (both

vertical and horizontal) experienced by sprinters throughout the

support (contact)phase if we are to bring this topic to a meaningful

conclusion. From what I have been able to gather, the conclusions

drawn from the Weyand study were based on forces generatd a one

point, not throughout contact. If I am wrong I would like to see

all the force data from touchdown to takeoff on a track, not

treadmill. Thus can you or anyone else supply this? From all the

comments made on this topic in the past few weeks I would think it

is readily available.

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

[Guest guest]

>

>

Dear Mr Yessis, many thanks for your response. Please find my answers

to your e-mail below.

You

> You are getting ahead of what I proposed -- one topic at a time.

Me:

Ok, you are right, we agreed to do just this. See the section below.

I would like to ask you to comment on that. In order to start a

discussion, I need some information from you. The viewpoints of Barry

and others are clear (they have repeated their arguments several

times). You do not seem to agree with their reasoning. To be able to

continue I would like to know your view on the topic at hand. For a

good discussion we need to know both viewing points. To my limited

knowledge the interpretation of the Weyand study by Barry and others

does not seem to be flawed. Please enlighten me to where the crux

lies in interpreting the data. Where do you disagree? This would

really improve my insight in the matter at hand.

> > >if time of executiong the limb

> > > movements is basically the same, but one runmner covers greater

> > > distance with his limbs, can speed of limb movement be the same?

> >

> > Stefan's response

> >

> > In the example you stated, limb movement would be faster for the

> > person covering greater distance with his limbs.

So, in keeping one topic at a time. You asked me the above question

and I responded. I would like to ask you if you could comment on the

above, what does it has do with limb speed and whether it is

important in better runners.

In the remainder of your response, you also address other topics

(like definition of overstriding, ground contact length, ground

reaction force). I would also like to ask you to discuss one topic at

a time. Let’s resume or discussion with your above stated question

and my answer. Please be so kind to explain why your question (and my

answer) is critical in the discussion of limb speed between faster

and slower runners.

Many thanks again for your willingness to participate in this

disussion. I am looking forward to your reply.

Best regards,

Stefan IJmker

Haarlem, the Netherlands

[Guest guest]

" The question of limb speed has not been answered by Barry and others

who maintsin that limb speed is not important or is the same in

better runners. We first need an answer from them to determine if

their conclusions are accurate or warranted by the Weyand study. "

Dr. Yessis, you say that you need an answer from me and others, then

proceed to state that " Barry and others maintain limb speed is not

important or is the same in better runners " . You've already decided

that is the answer. Now you need to prove whether that answer is

right or wrong, using independent research by locomotion experts.

Once again, you fail to provide any information and you

continue to ask others to provide it for you. We've already

determined that your information is incorrect on several issues in

previous posts.

" If I am going to continue in this discussion in which I stated and

will restate that their conclusions are incorrect they have to

answer my queries, not just reply to them. "

It is not enough to say we are incorrect, you need to show

independent proof that what we state is incorrect. So far you've been

unable to do so.

" What do the authors mean by overstriding? Has anyone ever seen

this on live video with an accomplished runner? ( I don't mean

staged, I mean in a real race) Is there any data to support the

notion of overstriding in sprinters? marathoners? "

Exactly where in the Weyand study is overstriding mentioned? I've

read that study more times than you can imagine and I don't

recall " overstriding " being mentioned. Do you mean elongated step?

That term is mentioned:

" Within groups of male and female runners, contact lengths varied

little or not at all in relation to top speed. Although elongated

steps would provide a speed advantage by increasing the time

available to apply ground force, runners do not exercise this option

because unnaturally long steps compromise the ability of the active

muscles to apply the ground force necessary to elevate the body for

the ensuing step. By worsening the mechanical advantage and

disrupting the natural spring-like behavior of the leg (8),

unnaturally elongated steps increase the muscle forces and volumes

that must be recruited per unit of force applied to the

ground (22). Reductions in the ground force applied in relation to

the muscle forces generated would directly reduce maximum ground

forces and therefore also reduce top running speeds. "

If you think that means overstriding you're wrong. Elongated steps

refer to time on the ground, not overstriding, where the foot lands

forward (generally on the heel) of the COM. You simply misunderstood

that portion of the study.

" In regard to ground forces, we need the actual forces (both

vertical and horizontal) experienced by sprinters throughout the

support (contact)phase if we are to bring this topic to a meaningful

conclusion. From what I have been able to gather, the conclusions

drawn from the Weyand study were based on forces generatd a one

point, not throughout contact. If I am wrong I would like to see

all the force data from touchdown to takeoff on a track, not

treadmill. Thus can you or anyone else supply this? From all the

comments made on this topic in the past few weeks I would think it

is readily available. "

Dr Yessis, this has been the modus operandi of your posts, this

expectation that we have to continually supply information for you to

decide whether or not you think it is right. Yet you never provide

data, other than purely anecdotal information, to support your

theories. If you have no data other than anecdotal then how can you

expect us to accept your theories as correct. What you ask of us, provide for us

in

return. We've given, you have not. Unless and until you can show

proof from independent research to verify your theories, you are

wrong Dr. Yessis.

If you disagree with the preceeding, provide information that you've

gathered from independent research to prove that you're theories are

correct.

" ...if we are to bring this topic to a meaningful conclusion "

Absent proof of your theories, the topic has come to a meaningful

conclusion.

Barry Ross

Los Angeles, Ca.

[Guest guest]

> You are getting ahead of what I proposed -- one topic at a time.

>

> The question of limb speed has not been answered by Barry and others

> who maintsin that limb speed is not important or is the same in

> better runners. We first need an answer from them to determine if

> their conclusions are accurate or warranted by the Weyand study.

>

> If I am going to continue in this discussion in which I stated and

> will restate that their conclusions are incorrect they have to

> answer my queries, not just reply to them.

>

> (1)Thus I will not at this time address your question. When I do

> however, we will need to define some terms. What do the authors

> mean by overstriding? Has anyone ever seen this on live video with

> an accomplished runner? ( I don't mean staged, I mean in a real

> race) Is there any data to support the notion of overstriding in

> sprinters? marathoners?

>

> (2)In regard to distance traveled by the leg during support, have

> you read my book Explosive Running? It may help you better

> understand this and many other points being raised.

>

> (3) In regard to ground forces, we need the actual forces (both

> vertical and horizontal) experienced by sprinters throughout the

> support (contact)phase if we are to bring this topic to a meaningful

> conclusion. From what I have been able to gather, the conclusions

> drawn from the Weyand study were based on forces generatd a one

> point, not throughout contact. If I am wrong I would like to see

> all the force data from touchdown to takeoff on a track, not

> treadmill. Thus can you or anyone else supply this? From all the

> comments made on this topic in the past few weeks I would think it

> is readily available.

****

Dr. Yessis,

I'm new to this discussion, but thought I could be of some assistance.

You requested force data from running on a track instead of a

treadmill so I will suggest you find the following article as it

includes clear graphs of vertical force, horizontal force, joint

moments and EMG. The maximum speed of the study subjects was between

9.23 and 10.26 meters per second. They ran at speeds of 70%, 80%, 90%

and 100% on a 10 m x 1.2 m force platform covered with tartan in an

indoor facility.

Kuitunen, S., Komi, P.V. & Kyröläinen, H. 2002. Knee and ankle joint

stiffness in sprint running. Medicine and Science in Sports and

Exercise 34(1), pp. 166-173.

Please see if the article provides what you were looking for.

Janne Alasalmi

Jyväskylä, Finland

[Guest guest]

Thank you for your assistance. I should have clarified that I am

not seeking this information for my edification. My problem is with

the conclusions drawn by Barry and others in regard to the Weyand

study. They state that there are no horizontal forces at push-off

and imply that vertical forces are the main forces involved in

running. What I'm asking for is substantiation or hard data to

support this view. If this is what they maintain, it is up to them

to substantiate their point.

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

> > You are getting ahead of what I proposed -- one topic at a time.

> >

> > The question of limb speed has not been answered by Barry and

others

> > who maintsin that limb speed is not important or is the same in

> > better runners. We first need an answer from them to determine

if

> > their conclusions are accurate or warranted by the Weyand study.

> >

> > If I am going to continue in this discussion in which I stated

and

> > will restate that their conclusions are incorrect they have to

> > answer my queries, not just reply to them.

> >

> > (1)Thus I will not at this time address your question. When I do

> > however, we will need to define some terms. What do the authors

> > mean by overstriding? Has anyone ever seen this on live video

with

> > an accomplished runner? ( I don't mean staged, I mean in a real

> > race) Is there any data to support the notion of overstriding in

> > sprinters? marathoners?

> >

> > (2)In regard to distance traveled by the leg during support, have

> > you read my book Explosive Running? It may help you better

> > understand this and many other points being raised.

> >

> > (3) In regard to ground forces, we need the actual forces (both

> > vertical and horizontal) experienced by sprinters throughout the

> > support (contact)phase if we are to bring this topic to a

meaningful

> > conclusion. From what I have been able to gather, the

conclusions

> > drawn from the Weyand study were based on forces generatd a one

> > point, not throughout contact. If I am wrong I would like to see

> > all the force data from touchdown to takeoff on a track, not

> > treadmill. Thus can you or anyone else supply this? From all the

> > comments made on this topic in the past few weeks I would think

it

> > is readily available.

>

> ****

>

> Dr. Yessis,

>

> I'm new to this discussion, but thought I could be of some

assistance.

> You requested force data from running on a track instead of a

> treadmill so I will suggest you find the following article as it

> includes clear graphs of vertical force, horizontal force, joint

> moments and EMG. The maximum speed of the study subjects was

between

> 9.23 and 10.26 meters per second. They ran at speeds of 70%, 80%,

90%

> and 100% on a 10 m x 1.2 m force platform covered with tartan in an

> indoor facility.

>

> Kuitunen, S., Komi, P.V. & Kyröläinen, H. 2002. Knee and ankle

joint

> stiffness in sprint running. Medicine and Science in Sports and

> Exercise 34(1), pp. 166-173.

>

> Please see if the article provides what you were looking for.

>

> Janne Alasalmi

> Jyväskylä, Finland

>

[Guest guest]

If the interpretations by Barry and others were clear, we would not

be having this discussion. For example, you agree that limb speed

must be faster if time of repositioning the legs is the same if

speed is to be greater. But yet, Barry and others do not agree with

this. This is where the problem is. They have shown no

substantiation for this disagreement. What then is clear?

My question was not directed to you only in regard to limb speed.

We need the response from the people who maintain that this is not

so. Barry refuses to answer whether he agrees with this formula from

physics and its application thus, giving my views at this time will

not serve any purpose. The crux of this whole discussion is to

determine whether the conclusions of the Weyand study are accurate

and can be applied in practice.

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

> >

> >

> Dear Mr Yessis, many thanks for your response. Please find my

answers

> to your e-mail below.

>

> You

> > You are getting ahead of what I proposed -- one topic at a time.

>

> Me:

> Ok, you are right, we agreed to do just this. See the section

below.

> I would like to ask you to comment on that. In order to start a

> discussion, I need some information from you. The viewpoints of

Barry

> and others are clear (they have repeated their arguments several

> times). You do not seem to agree with their reasoning. To be able

to

> continue I would like to know your view on the topic at hand. For

a

> good discussion we need to know both viewing points. To my limited

> knowledge the interpretation of the Weyand study by Barry and

others

> does not seem to be flawed. Please enlighten me to where the crux

> lies in interpreting the data. Where do you disagree? This would

> really improve my insight in the matter at hand.

>

> > > >if time of executiong the limb

> > > > movements is basically the same, but one runmner covers

greater

> > > > distance with his limbs, can speed of limb movement be the

same?

> > >

> > > Stefan's response

> > >

> > > In the example you stated, limb movement would be faster for

the

> > > person covering greater distance with his limbs.

>

> So, in keeping one topic at a time. You asked me the above

question

> and I responded. I would like to ask you if you could comment on

the

> above, what does it has do with limb speed and whether it is

> important in better runners.

>

> In the remainder of your response, you also address other topics

> (like definition of overstriding, ground contact length, ground

> reaction force). I would also like to ask you to discuss one topic

at

> a time. Let’s resume or discussion with your above stated

question

> and my answer. Please be so kind to explain why your question (and

my

> answer) is critical in the discussion of limb speed between faster

> and slower runners.

>

> Many thanks again for your willingness to participate in this

> disussion. I am looking forward to your reply.

>

> Best regards,

> Stefan IJmker

> Haarlem, the Netherlands

>

[Guest guest]

My apologies for using the term " overstriding " . I thought I had

read this but it certainly was not in what you stated.

Rather than discuss my modus operandi I keep asking questions for

you and others to answer to find out where your substantiation for

your information comes from. I'm not asking for additional

information, I'm asking for information to support your

interpretations. You maintain that you have supplied this

information, but when closely examined, you have not.

When I receive actual data from you substantiating your view, then

we may be able to proceed.

For example, you keep tossing the question of limb speed back and

not answering it. You stated that it was not important. Where is

your substantiation that it's not important?

You state that there are no horizontal forces at push-off. Where is

the data to substantiate this view?

You use the spring model as being synonymous with the stretch reflex

but yet when I have asked you if this is true you refused to answer

the question. Asking me to prove it usually implies that you do not

have proof for your statement. In the scientific community, the one

who is trying to prove a hypothesis has the burden of proof to

provide evidence.

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

>

>

> " The question of limb speed has not been answered by Barry and

others

> who maintsin that limb speed is not important or is the same in

> better runners. We first need an answer from them to determine if

> their conclusions are accurate or warranted by the Weyand study. "

>

>

> Dr. Yessis, you say that you need an answer from me and others,

then

> proceed to state that " Barry and others maintain limb speed is not

> important or is the same in better runners " . You've already decided

> that is the answer. Now you need to prove whether that answer is

> right or wrong, using independent research by locomotion experts.

> Once again, you fail to provide any information and you

> continue to ask others to provide it for you. We've already

> determined that your information is incorrect on several issues in

> previous posts.

>

> " If I am going to continue in this discussion in which I stated and

> will restate that their conclusions are incorrect they have to

> answer my queries, not just reply to them. "

>

> It is not enough to say we are incorrect, you need to show

> independent proof that what we state is incorrect. So far you've

been

> unable to do so.

>

> " What do the authors mean by overstriding? Has anyone ever seen

> this on live video with an accomplished runner? ( I don't mean

> staged, I mean in a real race) Is there any data to support the

> notion of overstriding in sprinters? marathoners? "

>

> Exactly where in the Weyand study is overstriding mentioned? I've

> read that study more times than you can imagine and I don't

> recall " overstriding " being mentioned. Do you mean elongated step?

> That term is mentioned:

>

> " Within groups of male and female runners, contact lengths varied

> little or not at all in relation to top speed. Although elongated

> steps would provide a speed advantage by increasing the time

> available to apply ground force, runners do not exercise this

option

> because unnaturally long steps compromise the ability of the active

> muscles to apply the ground force necessary to elevate the body for

> the ensuing step. By worsening the mechanical advantage and

> disrupting the natural spring-like behavior of the leg (8),

> unnaturally elongated steps increase the muscle forces and volumes

> that must be recruited per unit of force applied to the

> ground (22). Reductions in the ground force applied in relation to

> the muscle forces generated would directly reduce maximum ground

> forces and therefore also reduce top running speeds. "

>

> If you think that means overstriding you're wrong. Elongated steps

> refer to time on the ground, not overstriding, where the foot lands

> forward (generally on the heel) of the COM. You simply

misunderstood

> that portion of the study.

>

> " In regard to ground forces, we need the actual forces (both

> vertical and horizontal) experienced by sprinters throughout the

> support (contact)phase if we are to bring this topic to a

meaningful

> conclusion. From what I have been able to gather, the conclusions

> drawn from the Weyand study were based on forces generatd a one

> point, not throughout contact. If I am wrong I would like to see

> all the force data from touchdown to takeoff on a track, not

> treadmill. Thus can you or anyone else supply this? From all the

> comments made on this topic in the past few weeks I would think it

> is readily available. "

>

> Dr Yessis, this has been the modus operandi of your posts, this

> expectation that we have to continually supply information for you

to

> decide whether or not you think it is right. Yet you never provide

> data, other than purely anecdotal information, to support your

> theories. If you have no data other than anecdotal then how can you

> expect us to accept your theories as correct. What you ask of us,

provide for us in

> return. We've given, you have not. Unless and until you can show

> proof from independent research to verify your theories, you are

> wrong Dr. Yessis.

>

> If you disagree with the preceeding, provide information that

you've

> gathered from independent research to prove that you're theories

are

> correct.

>

> " ...if we are to bring this topic to a meaningful conclusion "

>

> Absent proof of your theories, the topic has come to a meaningful

> conclusion.

>

> Barry Ross

> Los Angeles, Ca.

>

[Guest guest]

For reasons I’ve mentioned in previous responses, I’ve vowed not to write

again on this topic, but I will consider this a ‘say less/learn more’ kind

of

post.

Since I’ve often noted that the problem with these Weyand/mechanics speed

threads has been the inability of both sides to understand what they are

arguing against and not just what they are arguing for, at this point it is

only

fair to take the time to determine exactly what your position is relative to

the mechanics of speed. Therefore, I’m posing five questions which should

help

me see your side of these issues:

1) Were you to conduct research which began with the premise that sprinting

was simply the product of stride frequency and stride length, what would be

the mechanical variables affecting stride length and stride frequency that you

would consider in your study? In other words, what are the mechanical

alternatives by which athletes could achieve faster top speeds? Again, I’d

emphasize the mechanical alternatives.

2) Could you explain what things are changing mechanically to cause a

sprinter to come to the end of acceleration? In other words, what would cause

net

propulsion to be zero at top speed?

3) Once an athlete is up to speed, what is happening to the athlete’s torso

during contact time? In other words, if the grounded foot results in

breaking action what is happening to the athlete’s center of mass?

4) What structure causes the horizontal propulsive forces you have observed

on toe-off? In other words, is the foot (and musculature of that foot) the

primary lever for these horizontal forces?

5) What do you believe is the mechanical limit or barrier to speed? In other

words, what mechanical constraints impact upon an athlete’s faster top end

speeds?

Please note that these were the same questions posed to me in my first round

of discussions with Dr. Weyand.

Ken Jakalski

Lisle HS

Lisle, IL

[Guest guest]

" If the interpretations by Barry and others were clear, we would not

be having this discussion. They have shown no substantiation for

this disagreement. "

" Asking me to prove it usually implies that you do not have proof for

your statement. "

" In the scientific community, the one who is trying to prove a

hypothesis has the burden of proof to provide evidence. "

Dr. Yessis, apparently there is a misconception in this discussion,

so rather than ignoring it, let's address it now:

Dr. Weyand and his associates, recognized experts in the field of

biped and quadruped locomotion, hypothesized that faster top running

speeds are achieved with greater ground forces not more rapid leg

movements and used that as the title of their subsequent study. They

provided ample evidence, including citations to 30 other studies, to

backup to their conclusions.

Among those conclusions is the following statement:

" In addition to advancing the understanding of human speed, our

results offer a more general and unexpected link between the

physiological features of swift runners and the mechanical basis of

their higher speeds. Certainly, top sprinters have faster muscle

fibers and greater muscular power available to reposition their limbs

yet do so little or no faster than average and slow human runners do.

From this result, we infer that faster fiber speeds do not allow legs

to be repositioned appreciably faster. Although the activation of the

flexor muscles and tendons that reposition the limb during the swing

period is considerable at high speeds, this activation likely occurs

to increase the storage and release of mechanical energy in the

oscillating limb rather than to generate mechanical power chemically

within these muscles. Similar patterns of flexor activation during

high-speed running in other species suggest that rapid limb

repositioning is achieved similarly and that minimum swing times

limit the top speeds of running animals. Accordingly, we suggest that

the mechanism by which faster muscle fibers confer faster top running

speeds in terrestrial cursors is not by decreasing minimum swing

times but by increasing the maximum rates at which force can be

applied to the ground. We conclude that human runners reach faster

top speeds not by repositioning their limbs more rapidly in the air

but by applying greater support forces to the ground. "

The basis of our statements on this site is found within the complete

body of the Weyand study. One needs to read the entire study (rather

than the abstract), which is readily available on the internet, to

see that our statements match the conclusions of the researchers. In

previous posts, you've stated that you did not disagree with the data

in the Weyand study but that you did disagree with the conclusion(s).

Any disagreement you have regarding accuracy (or lack thereof) of

those conclusion should be addressed to the researchers, not us. When

addressing the issues of contention, it is not sufficient to say that

one simply disagrees with the conclusion without giving a reason.

Hopefully, the reason for finding opposition to research is based

upon findings from other, equally well crafted research rather than

biased opinion or anecdotal evidence.

You stated, " My problem is with the conclusions drawn by Barry and

others in regard to the Weyand study. " You should not have a problem

with the conclusions we've drawn in regard to the Weyand study,

because in this particular case , we do have one advantage that most

others do not have when reviewing research data and conclusions;

we've spoken directly, and often, with the researcher, Weyand,

subsequent to the study's publication

For this reason, we have no misunderstanding about the data or

Weyand's conclusions of the study.

Misunderstanding of the Weyand study by others is not unusual because

terminology used among scientists might be used differently than the

way it is used by the lay person. For example, you stated, " My

apologies for using the term " overstriding. " I thought I had read

this but it certainly was not in what you stated. " The term you

misapplied was " elongated step " which referred to the length of time

of ground contact. An elongated step would fall under the term Step

Length.

Another term that is often misunderstood is Contact Length. Many

believe that the term refers to the length of time when the foot is

in contact with the ground, while the researcher uses it to describe

the forward distance the body moves during ground contact.

It's apparent that you've also misunderstood the term rapid

repositioning of the limbs, which the study addresses, " Despite the

widespread belief to the contrary, a more rapid repositioning of

limbs contributes little to the faster top speeds of swifter

runners. "

You stated, " Speed of the body is dependant on limb speed... "

Weyand's study concluded that this was not the case. Neither you nor

any other posters to this thread have provided opposing evidence from

other research, so readers of this thread should have a high level of

confidence that this is the case.

You've stated, " (Limb) Speed (more accurately velocity) equals

distance divided by time " and you've asked, " …if time of executing

the limb movements is basically the same, but one runner covers

greater distance with his limbs, can speed of limb movement be the

same? " You've asked why we've not answered this question. The reason

we've not answered is because question is not well phrased, making it

difficult to understand what you're asking. Using the definition of

speed you gave above to restate your question, we get the following:

if the time of executing the limb movements is basically the same,

but one runner covers greater distance with his limbs, can the

distance of the limb movement divided by time be the same as the time

of executing the limb movements. How can one compare the variable of

distance to the variable of time in the way your question is asked?

There are only two applications of the term " speed " regarding

running: Ground speed and speed of the limbs relative to ground speed.

We've seen that readers of the Weyand study often create confusion

when describing the forward speed of the limb and the time taken to

reposition the limb using the same term (i.e. the term " faster " ).

The forward speed of the runner (his legs, arms, and body) and the

time taken to reposition the limb are distinct variables. The first

is a forward speed or velocity (usually in meters per second).

The second is simply a time: seconds only. The statement

that " faster runners do not reposition their swing legs faster than

slow runners do " refers to the time taken to reposition the swing leg

and does not refer to the forward speed of the limb. In point of

fact, the authors of the Weyand study do not use the term " faster " to

describe the time taken to reposition the swing limb.

We have accepted the findings of the Weyand study and we have

provided training that fits the needs of our sprinters, distance

runners and athletes of other sports. We did not do so without doing

some analysis of our own. For example, we used Silicon Coach to

measure the speed of the retracting leg as it approaches toe-down

(you can see the results on my website, in the resources section).

Limb speed, measured from tracing the ankle, peaked at 0.25 m/s and

slowed to 0.09 m/s just prior to toe-down. The runner's forward speed

was in excess of 9 m/s. Many coaches, including you, instruct the

runner to accelerate the retracting leg down and backward to offset

braking at toe-down. Is the runner we measured using poor technique

by slowing the limb relative to the ground or is there some other

reason for reducing limb speed prior to toe-down?

In their 2003 study, " Swing-leg retraction: a simple control model

for stable running, " André Seyfarth et al, stated that reduction of

foot-velocity with respect to the ground was necessary to " improve

the stability of spring-mass running over a disturbances in the angle

of attack and leg stiffness. "

Rather than continuing to blindly accept the " instructions " from

promoters of " technique " training, we've turned to the information

provided by the researchers in the field of locomotion for

information. Then we tested, to the extent we were able, their

findings using OptoJump and Silicon Coach to see if it matched what

we should expect from what we read. It matched.

I've addressed the two statements you've previously posted: " Asking

me to prove it usually implies that you do not have proof for your

statement, " and " In the scientific community, the one who is trying

to prove a hypothesis has the burden of proof to provide evidence, "

that the proof of what we've stated is in the research documents

we've named and/or quoted from.

Since our proof is based on research conducted by independent

scientific study, the real issue is whether or not specific technique

training can survive the same standard of proof. We see no evidence

that the type of technique training,as offered by many coaches and

authors stands up to any scrutiny, let alone independent research.

Since " technique " training is so prevalent, I thought it would be

simple for a technique expert to provide scientific evidence

(not anecdotal) that what they do is both useful and necessary by

providing research that backs up their claims for specific technique

training. Apparently, I was wrong since none of the technique coaches

has been able to provide any. You certainly haven't provided any.

You and your colleagues hypothesise that technique training is

necessary. Prove it. Show the evidence.

You asked, " What then is clear? "

The answer: There is no justification for " technique " training.

Barry Ross

Los Angeles, CA

[Guest guest]

There is no doubt in my mind that this issue will not be resolved

by examining the separate facts as presented especially if my simple

question on limb speed is too complex.

Instead I will look at the Weyand study and the drawn conclusions as

a person who knows little about running but who knows science and

has an inquiring mind.

For example, the statement that " Dr. Weyand and his associates,

recognized experts in the field of biped and quadruped locomotion,

hypothesized that faster top running speeds are achieved with

greater ground forces not more rapid leg movements and used that as

the title of their subsequent study. They provided ample evidence,

including citations to 30 other studies, to backup to their

conclusions " .

If he and his associates had a strong understanding of running how

did they arrive at the conlusion that this topic was worthy of

research? Did he show the need for this study? Is there a conflict

in the literature as to the role of the legs and what produces the

force in push-off? Were studies addressing limb repositioning done

that showed the need for more study? If yes, what was the

prevailing evidence?

Since this study revolves around leg repositioning why was no role

given to this i.e., what role do the legs play? We are told that

leg action is not important nor is technique. If true, why do we

even have to reposition the legs? Why not just let them hang and

relax and land wherever?

In regard to conctact length why is the distance traveled during

contact so important? Is this the only time that the body moves

forward or is pushed forward (even though it is stated there are no

forces at push off)

That the limbs are repositioned via the release of elastic energy is

well established. What was not addressed in the study was what

role they play in running. Don't the legs create a forward force

when driven forward with great acceleration? Why was this ignored?

Does this action not contribute to forward speed? If you do this in

a standing position you will fall forward; isn't this a force? If

the limbs do not contribute, why do we swing our arms and legs up or

forward in jumping? Spring -mass studies show the importance of

these actions.

Great importance is given to ground reaction forces. From what can

be found in the discussion the ground reaction forces were measured

at touchdown where vertical foreces were greater than horizontal.

This is understandable. But how can vertical forces propel the body

forward? Why are there no ground forces at the the moment of

takeoff? How can this be especially in view of EMG studies done

showing the role of the Achilles tendon and calf muscles in

returning energy for the push off. Most studies done on return of

energy use ankle joint extension which (according to the

conclusions)is unimportant and plays no role in running.

As any good researcher will tell you it is necessary to explain

the results. If this is not possible more studies are called for.

Thus if ground reaction forces are the key to faster running speeds

we should be told how these forces are created and used. The role

of gravity in this case is overestimated. Were calculations done to

measure the force produced by gravity? If they were how could they

conclude that gravity is the main force to contend with? This does

not require rocket science. Simply calculate the force produced by

a free falling body over a distance of 1-2 inches and you will be

unable to produce up to 5 times bodyweight force.

Thus how is up to 5 times body weight force created? Does it exist

in the isometric contraction of the leg muscles as was postulated?

But how can this be when no to very little movement in the leg

joints takes place during the latter half of the contact phase?

If the vertical forces are so important in forward propulsion as we

are led to believe in the spring-mass model, why does the leg remain

bent in the knee at takeoff? This indicates a less than total

return of energy from a relatively small amount of ground force

created by gravity. Is this how the spring model is used to

describe running? Does it take into consideration horizontal

forces? If yes where is the data? If the spring-mass experts use

only vertical force data (which they must to describe spring action)

how do they reconcile this apparent discrepancy?

I can go on but I hope this is sufficient to show that the study

and its conclusions did little if anything to clarify and explain

what takes place in running.

But if you and others still believe in the apparent incorrect

conclusions I will leave you with the conclusion of the spring model

experts who describe running as " a ball bouncing down the track " .

To put this conclusion into practice have your runners practice

bouncing as they " run " . To create more force have them bounce

higher and higher to create more ground force and its resultant

speed.

If you prefer to think of running as " a spring bouncing down the

track " , have the runners practice with pogo sticks to get a better

feel for the spring action on each step. To cover more distance

have them strive for more height on each jump.

I apologize for being facetious but isn't this a logical conclusion

to draw from the experts?

~~~~~~~~~~~~~~~~~~~~~~

Yessis, Ph.D

President, Sports Training, Inc.

www.dryessis.com

PO Box 460429

Escondido, CA 92046

~~~~~~~~~~~~~~~~~~~

>

> " If the interpretations by Barry and others were clear, we would

not

> be having this discussion. They have shown no substantiation for

> this disagreement. "

> " Asking me to prove it usually implies that you do not have proof

for

> your statement. "

> " In the scientific community, the one who is trying to prove a

> hypothesis has the burden of proof to provide evidence. "

>

> Dr. Yessis, apparently there is a misconception in this

discussion,

> so rather than ignoring it, let's address it now:

>

> Dr. Weyand and his associates, recognized experts in the field of

> biped and quadruped locomotion, hypothesized that faster top

running

> speeds are achieved with greater ground forces not more rapid leg

> movements and used that as the title of their subsequent study.

They

> provided ample evidence, including citations to 30 other studies,

to

> backup to their conclusions.

>

> Among those conclusions is the following statement:

>

> " In addition to advancing the understanding of human speed, our

> results offer a more general and unexpected link between the

> physiological features of swift runners and the mechanical basis

of

> their higher speeds. Certainly, top sprinters have faster muscle

> fibers and greater muscular power available to reposition their

limbs

> yet do so little or no faster than average and slow human runners

do.

> From this result, we infer that faster fiber speeds do not allow

legs

> to be repositioned appreciably faster. Although the activation of

the

> flexor muscles and tendons that reposition the limb during the

swing

> period is considerable at high speeds, this activation likely

occurs

> to increase the storage and release of mechanical energy in the

> oscillating limb rather than to generate mechanical power

chemically

> within these muscles. Similar patterns of flexor activation during

> high-speed running in other species suggest that rapid limb

> repositioning is achieved similarly and that minimum swing times

> limit the top speeds of running animals. Accordingly, we suggest

that

> the mechanism by which faster muscle fibers confer faster top

running

> speeds in terrestrial cursors is not by decreasing minimum swing

> times but by increasing the maximum rates at which force can be

> applied to the ground. We conclude that human runners reach faster

> top speeds not by repositioning their limbs more rapidly in the

air

> but by applying greater support forces to the ground. "

>

> The basis of our statements on this site is found within the

complete

> body of the Weyand study. One needs to read the entire study

(rather

> than the abstract), which is readily available on the internet, to

> see that our statements match the conclusions of the researchers.

In

> previous posts, you've stated that you did not disagree with the

data

> in the Weyand study but that you did disagree with the conclusion

(s).

> Any disagreement you have regarding accuracy (or lack thereof) of

> those conclusion should be addressed to the researchers, not us.

When

> addressing the issues of contention, it is not sufficient to say

that

> one simply disagrees with the conclusion without giving a reason.

>

> Hopefully, the reason for finding opposition to research is based

> upon findings from other, equally well crafted research rather

than

> biased opinion or anecdotal evidence.

>

> You stated, " My problem is with the conclusions drawn by Barry and

> others in regard to the Weyand study. " You should not have a

problem

> with the conclusions we've drawn in regard to the Weyand study,

> because in this particular case , we do have one advantage that

most

> others do not have when reviewing research data and conclusions;

> we've spoken directly, and often, with the researcher,

Weyand,

> subsequent to the study's publication

>

> For this reason, we have no misunderstanding about the data or

> Weyand's conclusions of the study.

>

> Misunderstanding of the Weyand study by others is not unusual

because

> terminology used among scientists might be used differently than

the

> way it is used by the lay person. For example, you stated, " My

> apologies for using the term " overstriding. " I thought I had read

> this but it certainly was not in what you stated. " The term you

> misapplied was " elongated step " which referred to the length of

time

> of ground contact. An elongated step would fall under the term

Step

> Length.

>

> Another term that is often misunderstood is Contact Length. Many

> believe that the term refers to the length of time when the foot

is

> in contact with the ground, while the researcher uses it to

describe

> the forward distance the body moves during ground contact.

>

> It's apparent that you've also misunderstood the term rapid

> repositioning of the limbs, which the study addresses, " Despite

the

> widespread belief to the contrary, a more rapid repositioning of

> limbs contributes little to the faster top speeds of swifter

> runners. "

>

> You stated, " Speed of the body is dependant on limb speed... "

> Weyand's study concluded that this was not the case. Neither you

nor

> any other posters to this thread have provided opposing evidence

from

> other research, so readers of this thread should have a high level

of

> confidence that this is the case.

>

> You've stated, " (Limb) Speed (more accurately velocity) equals

> distance divided by time " and you've asked, " …if time of executing

> the limb movements is basically the same, but one runner covers

> greater distance with his limbs, can speed of limb movement be the

> same? " You've asked why we've not answered this question. The

reason

> we've not answered is because question is not well phrased, making

it

> difficult to understand what you're asking. Using the definition

of

> speed you gave above to restate your question, we get the

following:

> if the time of executing the limb movements is basically the same,

> but one runner covers greater distance with his limbs, can the

> distance of the limb movement divided by time be the same as the

time

> of executing the limb movements. How can one compare the variable

of

> distance to the variable of time in the way your question is

asked?

>

> There are only two applications of the term " speed " regarding

> running: Ground speed and speed of the limbs relative to ground

speed.

>

> We've seen that readers of the Weyand study often create confusion

> when describing the forward speed of the limb and the time taken

to

> reposition the limb using the same term (i.e. the term " faster " ).

>

> The forward speed of the runner (his legs, arms, and body) and the

> time taken to reposition the limb are distinct variables. The

first

> is a forward speed or velocity (usually in meters per second).

>

> The second is simply a time: seconds only. The statement

> that " faster runners do not reposition their swing legs faster

than

> slow runners do " refers to the time taken to reposition the swing

leg

> and does not refer to the forward speed of the limb. In point of

> fact, the authors of the Weyand study do not use the term " faster "

to

> describe the time taken to reposition the swing limb.

>

> We have accepted the findings of the Weyand study and we have

> provided training that fits the needs of our sprinters, distance

> runners and athletes of other sports. We did not do so without

doing

> some analysis of our own. For example, we used Silicon Coach to

> measure the speed of the retracting leg as it approaches toe-down

> (you can see the results on my website, in the resources section).

> Limb speed, measured from tracing the ankle, peaked at 0.25 m/s

and

> slowed to 0.09 m/s just prior to toe-down. The runner's forward

speed

> was in excess of 9 m/s. Many coaches, including you, instruct the

> runner to accelerate the retracting leg down and backward to

offset

> braking at toe-down. Is the runner we measured using poor

technique

> by slowing the limb relative to the ground or is there some other

> reason for reducing limb speed prior to toe-down?

>

> In their 2003 study, " Swing-leg retraction: a simple control model

> for stable running, " André Seyfarth et al, stated that reduction

of

> foot-velocity with respect to the ground was necessary to " improve

> the stability of spring-mass running over a disturbances in the

angle

> of attack and leg stiffness. "

>

> Rather than continuing to blindly accept the " instructions " from

> promoters of " technique " training, we've turned to the information

> provided by the researchers in the field of locomotion for

> information. Then we tested, to the extent we were able, their

> findings using OptoJump and Silicon Coach to see if it matched

what

> we should expect from what we read. It matched.

>

> I've addressed the two statements you've previously

posted: " Asking

> me to prove it usually implies that you do not have proof for your

> statement, " and " In the scientific community, the one who is

trying

> to prove a hypothesis has the burden of proof to provide

evidence, "

> that the proof of what we've stated is in the research documents

> we've named and/or quoted from.

>

> Since our proof is based on research conducted by independent

> scientific study, the real issue is whether or not specific

technique

> training can survive the same standard of proof. We see no

evidence

> that the type of technique training,as offered by many coaches and

> authors stands up to any scrutiny, let alone independent research.

>

> Since " technique " training is so prevalent, I thought it would be

> simple for a technique expert to provide scientific evidence

> (not anecdotal) that what they do is both useful and necessary by

> providing research that backs up their claims for specific

technique

> training. Apparently, I was wrong since none of the technique

coaches

> has been able to provide any. You certainly haven't provided any.

>

> You and your colleagues hypothesise that technique training is

> necessary. Prove it. Show the evidence.

>

> You asked, " What then is clear? "

>

> The answer: There is no justification for " technique " training.

>

> Barry Ross

> Los Angeles, CA

>