Re: Mechanics of speed

[Guest guest]

Ken,

It was interesting to see that you are agreeing with me on a critical issue,

one that you never would explain previously. Your last quote from

says it all

" A large part of the ankle movement that we see while the runner's foot is

on the ground is due to stretching and recoil of the Achilles tendon. The

tendon stretches enough for its role as a spring to be very significant. "

In your previous statements you stated that the ankle did not play a role in

running. What the ankle did was immaterial as it had nothing to do with GRF

since there were zero forces at toe off. Are you now saying that ankle

joint extension plays a major role in running? are you now disagreeing with

Weyand and others who are in agreement with your previous position ?

But isn't the stretching of the Achilles' tendon and its subsequent

shortening (recoil) an example of a stretch reflex?

or as Verkhoshansky states it, the stretch-shorten principle?

Also a spring gets compressed it does not get stretched except if pulled

apart. Are we to believe that the spring is first stretched during a

landing? how is this possible? or is it best if we equate spring

compression to the loading of the muscles as I previously stated with a

return of the energy accumulated in the ankle joint (Achilles' tendon and

calf muscles) since they are the only structures that are active in the

pushoff.

You and others are very welcome to use the example of a person on a pogo

stick jumping up and down on the track. But I believe you will agree that if

you ask just about anyone regardless of whether they are a runner or

non-runner, to visualize a bouncing ball or a person on a pogo stick, they

will describe someone bouncing up and down not running horizontally with

only a small vertical component.

If you try to duplicate the takeoff and landing that occurs in running with

a person on a pogo stick you'll find that it will be impossible for them to

exhibit any kind of action that looks like running. It will be a series of

stops and starts if they didn't fall flat on their face or butt first.

In regard to the bouncing ball analogy not only as stated the ball

will start to rotate, but the angle of takeoff will change.

Yessis, PhD

Professor Emeritus, CSUF

President, Sports Training Inc.

www.DrYessis.com <http://www.dryessis.com/>

CA, USA

[Guest guest]

Barry

You ask many questions which have little if anything to what has been said.

You seem to agree that the leg is accelerated down and back in the pawback.

Previously I believe you said that there was no pawback -- ground reaction

forces were due to gravity only. Are we now in agreement?

You make a big deal of looking at pictures but yet you don't seem to

understand that if the pictures come from live digital film (as they do in

my book) they are the same as looking at video clips. When using

cinematograms you can see the entire stride or couple of strides without

having to go forwards and backwards on the video. So yes we do a lot of

analysis of technique via the pictures taken from live digital tape. We do

not do any measurements of horizontal or vertical force (this is best done

in well-equipped laboratories) but we do look at their display in the

runners technique.

In regard to air time you are confusing a few issues. Since you found that

air time for faster runners is longer than it is for slower runners then you

should also know that they have a longer stride length which accounts for

the major difference in their speed. But if you try to increase airtime you

will be slowing down because of air resistance. This is the point I was

trying to make but you somehow got it all confused.

Why are you so concerned with how much force is developed when the runner

hits the ground? I don't care about this. I am more concerned with where

his foot hits the ground and where his body is when his foot leaves the

ground. These are the critical elements.

I didn't know a website could tell you everything I do in training. It shows

how you jump to conclusions without even finding out the basic information

needed. Just so you don't brainwash other people with your comments I will

let you know that we do a tremendous amount of strength training but only in

GPP. In SPP we do mostly specialized -- dynamic correspondence-- strength

and explosive exercises together with speed training. These exercises

produce much greater and faster results than mere strength training during

SPP.

Because you seem to be be so big on strength training perhaps you can tell

us what in the Weyand study which you say you follow, indicates the need for

strength training except to gain greater mass. Since gravity is the only

force involved in producing GRF (according to Weyand, you and others) why

not just get heavier runners? and if you somehow came to the conclusion

that strength training is needed, how do you know which exercises to use? I

ask this question because technique is downplayed and is not important to

you and others.

Yessis, PhD

Professor Emeritus, CSUF

President, Sports Training Inc.

www.DrYessis.com <http://www.dryessis.com/>

CA, USA

[Guest guest]

> Hi

>

> Is what you are implying, that by increasing the total force you thus

> increase its vertical and horizontal components. The angle/

> direction as

> well as the magnitude of the applied force will thus effect the

> horizontal

> and vertical components.

>

> In the same way that a pogo stick jumper leans more forward to get

> more

> speed :-to a maximum after which insufficient height is achieved to

> allow

> more speed that is the pogo comes to ground to early to effectively

> use the

> propulsion force to its fullest and the spring is not loaded as much

> because

> of the attitude of the spring to the ground. If the analogy of pogo

> stick

> transfers to the runner in this way, which it seems to as the leg is

> best

> used to store and amortise the stored energy in the time frame that

> sprinters have ground contact. (it seems that little else could

> happen in

> that short time), then training the leg to behave more spring like

> might be

> the best training for maximising high speed running. But that the

> angle of

> the actual force (that we broke down into its components) is

> important to

> and possibly a technique issue that needs addressing.

" Yes, to paragraph one and " quite right " to par. 2. To be technical I

wouldn't say I " implied " anything tho,

I'm saying that that is what the laws of the physics of motion and

vector analysis of the forces, says. As far as I'm concerned there

isn't any doubt about this. How running technique, equipment, etc.

fits in is debatable, at great length, and is (and should be) the

subject of great experimentation and scientific analysis.

Fair winds and happy bytes,

Dave Flory,

Flower Mound, TX, U.S.A.

[Guest guest]

Hi Dr. Yessis!

In a response post to Barry, you noted the following:

“So yes we do a lot of analysis of technique via the pictures taken from

live digital tape. We do

not do any measurements of horizontal or vertical force (this is best done

in well-equipped laboratories) but we do look at their display in the runners

technique.â€

I fully understand that it seems as if I am endlessly harping on this notion

of video, but here again is my point of clarification, which might have

been getting lost in your responses as to why neither the pictures nor the

method they were taken is problematic relative to the purpose of your book.

My concern is not with the camera itself, and not that you shot images with

live digital tape, or that you didn't focus on horizontal and vertical force

(which is understandable) but that excellent software is available (like

Dartfish and SiliconCoach) which could have been used in your 2006 revision to

demonstrate exactly the mechanics you are teaching. And you really don’t

need a well equipped laboratory to get valuable data. You simply need the

software, and you need to shoot segments without the camera panning to follow

the

runners, as it does in Explosive Running, And you need to establish a

metric or English measuring point in the image in order to do the calculations.

I

should think that, even for any book in your series, such as Explosive Golf,

this kind of analysis would be extremely helpful, since you can do swing

overlays, track the speed of the head, etc. Shot put and discus coaches are

also using these kinds of programs, and any sport where data on movement would

better enlighten the coach and athlete would be served by this minor

investment in time and technology.

We have been discussing what things change relative to the swinging limb,

and where and how the foot should be taught to land in order to achieve faster

forward speeds. And you are offering techniques taught in isolation at

considerably slower speeds as the means to affect mechanics at top speed. For

me,

there’s the rub.

I would be more inclined to accept your position--or continue the same

technique strategies-- had I not in front of me hundreds of sprint analysis

stills

and video clips showing no evidence of the mechanics you are suggesting

(like the pawback). And these images are of fairly accomplished athletes (9.1

m/s

or greater) who were trained for their entire high school careers in the

pawback or ‘claw,’ technique. The limb tracings clearly show no evidence

of

athletes applying the paw technique.

When I send these images to coaches who insist on training to achieve

pawback, the responses I receive are most interesting. The images which

clearly

show athletes not pawing, and the foot slowing before landing (the software

can track speed), receive the following explanation: The athletes are not

pawing back because they are not dorsiflexing, or they are not pawing because

they are spending too much time in the residual swing phase via a high back

kick. And then we have JAP 2000, which provides clear and compelling evidence

that swing time is not the variable affecting top end speed. And that was the

title of the paper: Faster top running speeds are achieved with greater

ground forces not more rapid leg movements.

If this is contrary to your belief, it seems that more precise supports than

the images used in your text would be in order. And I will agree that

these supports shouldn’t be from studies. What I am doing via analysis

software

is exactly what you are doing via your picture analysis—using applied

practitioner skills. However, I am not seeing the same things you are when I

apply

the standard of biomechanics software.

You will counter by saying that your images clearly demonstrate athletes

revealing your techniques (or showing poor technique), and I will say, for the

reasons I noted above, they don’t. They are interpretations of technique

that you and others will claim, with a career’s worth of confidence, they are

analyzing appropriately. I wish I were that good—or that video analysis had

not proved me wrong.

I 'coached' the pawback for at least twelve years. But I have no evidence

that this technique was ever applied by the athletes I coached in the

technique. And if such techniques were not being applied, then I can conclude

that

either 1) my teaching method was flawed or 2) these are clearly not mechanical

variables that need to be applied in order for athletes to achieve faster

speeds.

I agree that pictures are indeed worth a thousand words, but when my

pictures aren’t showing the same things yours are—do we question the

pictures..or

the words…or both?

Ken Jakalski

Lisle High School

Lisle, IL USA

[Guest guest]

Dr. Yessis,

The questions I asked has much to do with what has been said. Whether or not

you agree with that is a different issue.

In all of these discussions, you have never offered anything other than what

you think you see and that is not enough. You demand answers to questions

you pose to others while you act as if you have immunity from answering

questions asked of you.

You don't have that immunity.

For the reasons that Ken wrote in his last post and from my own experience,

I certainly do not agree with pawback. As far as I'm concerned neither you

nor anyone else as offered anything more than an interpretation of a visual

event. Absent force data your pawback theory has no legitimate case and

therefore it should be regarded as nothing more than an untested theory.

When you are presented with answers gleaned from research, you either ignore

them or make snide remarks about them. Since you refuse to answer many

questions challenging your knowledge and methods while at the same time

showing no recent research based information as to their viability as a

training tool, it appears that you're merely guessing as to how and why you

get improved training results from your theories.

In fact, you have been unable to provide a single citation from any current

research/researcher justifying your theories.

While providing outside legitimate, research based documentation would

certainly legitimatize your theory, it's doubtful that we'll see any.

Lest any of the readers of this post think that any result is better than no

result, guessing as to a workout protocol does not insure best possible

performances and could (and often does) increase risk of injury from

excessive workloads.

I don't believe that I said ground reaction forces are from gravity only. In

fact, I posted earlier that horizontal force is 60% of vertical force on the

first step out of the blocks, dropping down to 40% at step 3 and ultimately

to 10%.

Clearly, this information is important because these early horizontal

forces, which are greater percentages of the vertical force at the early

stage of running (start of the run through the first few strides) create the

horizontal portion of the stride.

Pictures tell us very little regardless of how they are obtained. I cannot

think of any legitimate researcher looking at images and guessing where and

how much force is applied at toe-down through toe-off.

You've admitted that you don't measure force because you don't have the

proper equipment. You also show distain for current research which has been

offered in response to your question about horizontal force during high

speed running.

If you don't measure force yourself and you don't agree with the large body

of research that shows horizontal forces to be very low, how then can

you decide where, when and how much force is applied?

You can't, Dr. Yessis, so you guess. You must do so because you've

eliminated other possibilities on your own.

Offering another explanation of what you think you see is not sufficient,

but outside sources that can offer current and corroborative documentation

for your theories would serve you well. However, I doubt you will find any.

Your images do not show rate of speed decrement. Rate of speed decrement can

be reduced (when the cause is understood) by applying simple strength

training exercises.

Your images do not show HOW each runner's form adapted to overall training.

You look at a beginning stage, middle stage and end stage and assume that

your " technique " training was the cause of the changes. You also claim that

you've got trainees in the weightroom, on the field doing drills and perhaps

running repeats.

Which of these training methods are doing the most in changing technique?

Are they all contributing equally? How do you assess any differences between

methods?

It's possible that you don't really care which is working as long as there

are improvements.

That's sad for those who are subject to training-by-guessing only since they

are subject to either misapplied work or general overwork when neither is

necessary. This is the penalty for any coach that has an " I always do what

I've always done " mentality despite the wealth of current research

information-information that significantly reduces guessing and reduces

exposure to risk.

The fact that, by your own words, you don't care about force development

when the runner hits the ground shows little regard for science in general

and for running in particular. What you call " critical elements " are truly

so-- and they are highly dependent on forces that by your own admission, you

don't account for and you don't care.

Your website tells me much of what I need to know about your strength

training program and your comments in this recent post verify that you are

not aware of more current research that clearly show why your methods are

not fully meeting the needs of the runner.

I've been where you are and it's not the right place to be. It's just more

of the same old stuff.

If there is any brainwashing, Dr. Yessis, it's not coming from me.

I am big on strength training and for good reason. It's clear from your

comments about which Weyand study I use that " indicates the need for

strength training except to gain greater mass " you have not read the paper

carefully or you did not understand it. In either case you jumped to an

erroneous conclusion. This is not harmful for you, but, potentially, it is

for those you train.

In fact, Weyand's study suggests that minimizing mass is most important. The

study states that " Our regression relationship indicates that altering the

support force applied by only one tenth of one body weight is sufficient to

alter top speed by one full meter per second. " In other words, increasing

support force while minimizing increase in mass will increase running speed.

Despite your guessing as to our purpose (and methodology), we know which

exercise to use to increase sprint performance while minimizing mass. In

other words it's based on what current research suggests rather than

guessing or using a shot-gun approach.

What has also become apparent, with not only me but also Ken Jakalski and

other users of our strength training system worldwide, is that running

technique changes as the athletes increase strength. This includes heel

strikers.

To make this statement perfectly clear, running form is altered by strength

training and short, fast and targeted speed runs.

Our strength workout for sprinters uses only one lift and averages 10 reps

per session. All loads equal or exceed 85% 1RM.

We are not concerned with GPP of SPP because it is not necessary (been

there, done that). We don't do any explosive lifts (their value is mythical

at best for any sport that requires running) because of their dependency on

maximal lifts.

We have not been fooled into using any " technique " training because there is

simply no justifiable reason to spend time on it.

Because newer research shows better targets for training than what was

offered in the '70s and '80s , we can limit workouts by focusing on what is

important. For sprinters (or runners in most sports), it's rate of speed

decrement, not technique.

We can asses major causes of speed decrements for each of our trainees and

we can predict, with greater than 97% accuracy, how fast they can run

distances from a few meters (distance over time) up to 5 minutes of running

(time over distance). We use targeted strength training to improve speed by

focusing on the cause of speed decrements.

This cannot be said for much of your training theory because it fails to

recognize where force must be applied, and therefore has inherent weaknesses

and doubtful adaptations.

Increases in speed causes vector changes. Increases and decreases in wind

cause vector changes. On a windless day, an elite runner could hit speeds

in excess of 25 mph, creating drag force. How is it that they can adapt for

the wind effect (or the reverse--a powerful headwind) without facing the

same in training sessions?

How do you train them to make the necessary changes in fractions of a

second?

You can't. No coach can-but the runner can, and does, make the changes by

themselves. So does the majority of bipedal and quadripedal runners who

don't use your training theories.

We can see the physical changes as they adapt: elimination of heel strike,

forward lean when necessary, higher knees, etc, without ANY drills. We also

see large reductions in speed decrement without training runs longer than

50m. Throughout the season, our average training run for sprinters up to

400m is approximately 30m with an average of 5 runs per training session.

We do not run them at all in the pre-season. We build a base line aerobic

capacity through fast walking in a manner that creates inefficiency, thereby

causing increased metabolic work.

Until you can show a clear, rational and research based opposition to

mass-specific force, the spring-mass model and the elimination of redundant

training technique, your theories should not only be suspect, but should

fall victim to Ockhams razor: What can be done with fewer is done in vain

with more.

Barry Ross

Los Angeles, USA.

=======================================

From: Supertraining [mailto:Supertraining ]

On Behalf Of Dr. Yessis

Sent: Friday, March 20, 2009 5:25 PM

To: Supertraining

Subject: Re: Mechanics of speed

Barry

You ask many questions which have little if anything to what has been said.

You seem to agree that the leg is accelerated down and back in the pawback.

Previously I believe you said that there was no pawback -- ground reaction

forces were due to gravity only. Are we now in agreement?

You make a big deal of looking at pictures but yet you don't seem to

understand that if the pictures come from live digital film (as they do in

my book) they are the same as looking at video clips. When using

cinematograms you can see the entire stride or couple of strides without

having to go forwards and backwards on the video. So yes we do a lot of

analysis of technique via the pictures taken from live digital tape. We do

not do any measurements of horizontal or vertical force (this is best done

in well-equipped laboratories) but we do look at their display in the

runners technique.

In regard to air time you are confusing a few issues. Since you found that

air time for faster runners is longer than it is for slower runners then you

should also know that they have a longer stride length which accounts for

the major difference in their speed. But if you try to increase airtime you

will be slowing down because of air resistance. This is the point I was

trying to make but you somehow got it all confused.

Why are you so concerned with how much force is developed when the runner

hits the ground? I don't care about this. I am more concerned with where

his foot hits the ground and where his body is when his foot leaves the

ground. These are the critical elements.

I didn't know a website could tell you everything I do in training. It shows

how you jump to conclusions without even finding out the basic information

needed. Just so you don't brainwash other people with your comments I will

let you know that we do a tremendous amount of strength training but only in

GPP. In SPP we do mostly specialized -- dynamic correspondence-- strength

and explosive exercises together with speed training. These exercises

produce much greater and faster results than mere strength training during

SPP.

Because you seem to be be so big on strength training perhaps you can tell

us what in the Weyand study which you say you follow, indicates the need for

strength training except to gain greater mass. Since gravity is the only

force involved in producing GRF (according to Weyand, you and others) why

not just get heavier runners? and if you somehow came to the conclusion

that strength training is needed, how do you know which exercises to use? I

ask this question because technique is downplayed and is not important to

you and others.

============================

[Guest guest]

Reading the many recent posts on the mechanics of running/sprinting, I am

very surprised that our knowledge does not seem to have improved in the

last 50 years, and there is no concensus on the relatively simple

biomechanical principles of running.

In a beautiful book written on sprint (however in German language) the

German trackexpert Toni Nett (probably a name still remembered by some of

the older internationally oriented coaches, if it was only for his famous

high-speed filmseries in the German track journal Leichtathletik from

nineteensixties to eighties)in 1969 devoted one chapter on (translated:)

the foward pulling of the body by the foot. He discusses the " pawing " or

" clawing " movement of the leg and foot and if the sprinter should be

consciously doing this.

He cited the opinion of the Bulgarian track coach Batscharoff, 1963 and

the Polish coach Kruczalak in 1960. Kruczalac also wrote an article about

the sprint mechanics called: To scissor or not to scissor, in the Polish

track and field journal.

1960, yes, but in 2009 we are still throwing useless metaphors at each

other sprinting like pogo sticks, elastic balls, or " phrases like: running

is falling, (Romanov) " running is bouncing " , making us look like the 7

blind men and the elephant.

Henk Kraaijehof

Amstelveen

Holland

> Hi Dr. Yessis!

> In a response post to Barry, you noted the following:

> “So yes we do a lot of analysis of technique via the pictures taken

> from

> live digital tape. We do

> not do any measurements of horizontal or vertical force (this is best

> done

> in well-equipped laboratories) but we do look at their display in the

> runners

> technique.â€

> I fully understand that it seems as if I am endlessly harping on this

> notion

> of video, but here again is my point of clarification, which might have

> been getting lost in your responses as to why neither the pictures nor

> the

> method they were taken is problematic relative to the purpose of your

> book.

> My concern is not with the camera itself, and not that you shot images

> with

> live digital tape, or that you didn't focus on horizontal and vertical

> force

> (which is understandable) but that excellent software is available (l

[Guest guest]

Hello Ken and Dr. Yessis,

I have not used Dartfish in my training yet and have not used pictures / filming

of any sort. I have trained track athletes but the majority of my strength

coaching as it relates to speed training has been with non-track athletes. For

example the many baseball players I have worked with who had the pressure of

increasing there 60 yd dash every year for the scouts day, never improved with

technique training. As I evaluated my teaching I discovered that they just

needed to run more. The fastest guys I have worked with have all had difficulty

with technique drills. Pawback and toe up drills were completely confusing to

them and made them look silly. One of the players I am refering to plays for

the NY Yankees and was the third fastest 60yd dash in the draft three years ago,

he ran a 6.38 sixty. I have more examples just like this of other players

playing professionally that fit the same model. Of the players that were not as

fast naturally, I had some that were coordinated with pawback drills and toe up

cueing but I did not see improvements in there times. Obviously I am not

working with track athletes day in and out, but just from my experience with

other non-track athletes getting in enough sprint work over a consistent time

period and a limited amount of weight training that is specific to the

individuals needs is what has worked. Just my two cents. I would like to thank

both of you as well as others for these posts, it has gotten me thinking and

evaluating what I intuitively knew but didnt trust myself right away with.

Doug Fairbanks

Boston, MA

[Guest guest]

Regarding Henk’s recent comments:

The question for me is: what methods the great applied practitioners were

using fifty years ago to diagnose the pawback as a mechanical means by which

athletes could achieve faster speeds? Did they simply observe this in elite

runners? If so, how did they validate/confirm what they were seeing?

The following point is something we need to consider relative to any visual

or video analysis of the swinging limb’s motion before touchdown: 1) it's

velocity with respect to the track and 2) it's velocity with respect to the

body

or center of mass.

And this is something that is often overlooked in a typical analysis of

swing mechanics. For example, note the post I received from biomechanist Thor

Bessier on this issue. My question to Professor Bessier: Short of filming

athletes on a treadmill, is there a way to separate the two [noted above] in

order

to get true limb speed, or is there a way to determine true limb speed by

separating the forward speed of the runner?

Here was his response:

“As for the velocity question, to get the true limb velocity, you have to

really calculate the velocity of the foot with respect to the body of interest

( e.g. center of mass). This is tricky to do in [in biomechanics software] as

you don’t have one marker that represents the COM! But you could do as you

suggested...calculate the horizontal velocity of the body (assume the COM to

be somewhere on the trunk) and at the same time, calculate the horizontal

velocity of the foot. Subtract the two and you will have the velocity of the

foot

with respect to the COM. Unfortunately not an easy measure, but it will give

you a much closer approximation of the real foot velocity with respect to

the body, without the need to go into a full kinematic analysis.â€

So should we be measuring the speed of the foot relative to the ground or

relative to the body’s center of gravity to get a clear picture of whether or

not a volitional pawback or scissor is happening? Further, does this even

matter? Why should we concern ourselves with this issue? It's important

because

it may help to explain why Tom Tellez said that the pawing action is actually

an illusion resulting from rapid hip extension. In other words, what we see

in watching a runner is all parts of the body moving at the same speed

relative to the center of mass, but how these individual limbs are moving

relative

to the track requires far more than just visual acuity, especially if making

such determinations not all that easy using advanced software. So what was

available to the applied practitioner fifty years ago?

It seems to me that a fixed body (CM) with no variable other than limb

movement would be the best way to make this determination. And perhaps that’s

why

JAP 2000 was such an elegant study relative to the issue of what the limbs

are doing, and whether or not the speed of the limbs is a factor in explaining

why certain athletes achieve faster top end speeds.

From a locomotion perspective, the pawback has to result in a collisional

force on landing with no slowing of the limb. Were this indeed the case, which

research indicates isn’t happening, the timing of the loading of the tendons

elastically into the middle of the stance phase completely swamps out any

useful loading that might be accomplished via initial impact.

Points to consider with this technique:

The speed of retraction needs to consider the speed of the athlete's mass.

Can we truly determine the speed of the limb back to the track using visual

analysis techniques?

The value in treadmill based studies is that we can get a better idea of

exactly what the leg is doing relative to the center of mass

If retraction speed via pawback was an essential mechanical means that

athletes use to increase speed, then I would expect that a pawback trained

athlete

would reveal swing times faster than slower athletes (at their top speeds).

JAP 2000 indicates that swing time is not a variable affecting top speed.

Further, there seems to be an intrinsic limit to how rapidly the limb can be

repositioned during running.

Ken Jakalski

Lisle HS

Lisle, IL USA

[Guest guest]

and ,

Are you disputing the spring mass model as an accurate description of how humans

run (bounce) down the track, or are you just reminding us that in the discussion

of vertical forces, horizontal forces are at work as well?  I don’t think

anyone is disputing that the direction the force is applied determines the

direction the object moves, but running is not about just a single force or

motion.

,

Your description of vertical forces increasing friction to allow for greater

horizontal forces is appealing, but this " friction or push model " is not how the

locomotion folks describe running.  Can you reconcile their description with

yours?  The study cited that disagrees with Weyand’s findings shows

vertical force increasing only through a portion of the acceleration phase.  In

your " model " what accounts for the continued increase in horizontal force once

vertical force peaks?

Everyone else,

Every time this subject comes up, we seem to have one group that wants to accept

the spring mass model and go from there, and others who question either the

model itself, Weyand’s 2000 study, or both.  Until ’s reference to

the Finnish study, no one questioning Weyand’s study brought forth any

independent evidence to support their position. Instead, we get into these red

herring discussions about conversion of vertical force into horizontal speed. 

Despite earlier statements about his belief in the spring mass model, it is

clear Dr. Yessis does not believe it is an accurate description of running. 

Does anyone have a reference to a study that calls into question the spring mass

model as an accurate description of how humans run?  I am sure there are some

studies that show it is not a perfect description, but is the model being

seriously questioned by serious scientists?

It is good for people to remind each other of basic physics, but shouldn’t we

start with the assumption that the research scientists over the past 20 years

have at least as good a grasp of physics as board members.  When they proposed,

tested and then accepted the spring mass model, do people really think they, as

a group, did not know what they were doing?

I don't know if or dispute the model, Weyand's study or both, but

Dr. Yessis  clearly does. Shouldn't the burden be on those who dispute widely

held scientific beliefs to prove their case, rather than the other way around.

Jon Haddan

Irvine, CA

---

[Guest guest]

I’ll use an anecdote to put this mechanics debate in perspective. One of my

favorite films is Wayne’s, The Shootist. In that film, Wayne, playing

an aging gunfighter dying of cancer, gives a young Ronnie a 'shootin’

lesson.'

During the lesson, Wayne says to , “You keep your hammer on an empty

chamber for safety.†responds, “and if you’re going out to face

somebody?â€

Wayne's response: “Then load six if your insides tells ya to.â€

And that’s my attitude regarding this discussion of sprint technique and

mechanics. If you’ve taught the pawback your entire career, and clearly

believe that this is an essential technique to help athletes run faster, then

by

all means keep doing so—load six if your insides tell ya to.â€

I’ll keep resting the hammer over science because my ‘insides’ tells me

that doing so makes the most sense.

At one point in my career I ‘taught’ the paw, claw, dorsiflexion, and

reduction of residual swing with the same authority and conviction and

arrogance born of experience that many others still do I changed because I

was not

confident the old school stuff gave me the right answers, and when new

insights came out that did provide them, I changed my methods, as did several

of

my colleagues, who were also entertaining the possibility that we might have

been looking at these issues in the wrong way.

I’m glad that I re-assessed what I was doing. My kids run faster and have

more fun training, and though I will always defend the old school masters for

their great wisdom and insight, I continue to remain open to the possibility,

as Mel noted, that we just might pinpoint something that we may have missed.

I’ll refer to his closing insight once again: " If you think that you have

the perfect training program, this means that you are entirely closed to any

suggestions, so why bother to ask anything more.â€

Ken Jakalski

Lisle High School

Lisle, IL USA

[Guest guest]

Maybe the ability to observe and correct a sprinter's global, is what one

could call the " sprint coaches' eye " ?

Don't forget that in the e.g. 1960 coaches did not have a lot of

sophisticated equipment to analysze sprints, like force plates, electronic

timing devices or videocamera's. Also their possiblities like equipment in

the field of conditioning or strength, were very limited compared to the

current situation. They had to rely on what they observed and corret it

according to the biomechanical standpoints of that time.

Maybe this eye is what separated superb coaches liek Bertl Sumser, from

less succesful ones. They developed their " limited coaching-options " to

the maximum instead of relying on technology only and getting confused by

that.

I am pretty sure that yesterday's sprint coaches would still be more

succesful that their modern collegues.

Personally I am very fond of technological developments and will always be

one of the first to try and implement them, but it will never take away my

sense of what is necessary to make a sprinter run faster and win in

competitions. Never let technology or scientific " quackery " like presented

in the last posts about mechanics of sprint get in the way of common sense

and experience. Technology is just a tool and so is its use, not a means

to an end! I am just curious how many of the contributors on this post

have really worked with sprinters on a daily base for a few years.

Henk Kraaijenhof

Amstelveen

Holland

[Guest guest]

Ken

It's hard if not impossible to continue discussion on this topic since your

mind is closed to anything different from what you believe occurs. In

addition you keep changing your opinion of the importance of ankle joint

extension and other actions such as pawback and knee drive.

I will no longer be involved in this discussion because it is fruitless. I

will however leave a few bits of proven information

for readers who want to understand what happens in running. You will

disagree mainly I believe because you are too hung up on measurement of

forces rather than understanding how forces are generated, in which

direction the forces are produced and how we get a resultant force.

First the body does not act as a spring. We can use the analogy of a spring

but that is where it ends. We deal with the body so we can only deal with

muscles and limbs and how they function. Measurement of forces does not

tell you what the muscles and limbs are doing to produce the force and its

direction. This is why I focus on running technique. Running technique

does not happen automatically as you imply. If only running were that

simple!

Your assumption that speed is constant and does not require the application

of additional force is erroneous. In fact, studies of the finalists in a

Tokyo Olympics showed that speed changed every 10 m. there was a slowdown

and then speed up to produce what can be called constant speed.

If the ankle joint extension was not important the runner would not execute

this action. If we use your explanation then a rebounder in basketball

would automatically be going up for rebounds without ever stopping or

exerting any extra force. If we apply this spring model to his actions we

would see that major loading occurs in the knee joint and returned mainly

in the knee joint extension. Why doesn't this happen in running? Why is

the ankle joint the only one that gets loaded more than the other joints?

but now you admit that the ankle joint extension is important but you never

say why.

Do not bring paraolympians into the discussion; that is a separate

discussion

The biggest error that you commit is believing that there is 100% return and

that it is passive. This is impossible. The greatest return ever measured

was only about 90%. In running the best estimates say about 70%. Where

does the extra force come from to maintain this constant speed or is it now

variable speed ?

Yessis, PhD

Professor Emeritus, CSUF

President, Sports Training Inc.

www.DrYessis.com <http://www.dryessis.com/>

CA, USA

[Guest guest]

Barry:

There is no need to continue this discussion because your mind is already

made up and you already know everything that I do and why I do it and how I

do it. But yet you have never seen me in action and know nothing about me

If you look at past posts you will see that I answered many of your

questions but you never responded to my answers. This usually means that

you agree. But yet you come up with these falsehoods that I have immunity

from answering questions. Perhaps if you answered my questions with an

understanding of what occurred rather than reciting what some researcher

found that may and may not apply to the discussion at hand, things might

have been different. Citing studies is not a way of showing understanding.

It only shows accumulation of facts which must still be put in place.

Something you have not done..

It's obvious that you do not agree with many things as for example pawback.

But yet, the one exercise that you say is the main one -- the dead lift--

mainly strengthens the glutes and hamstrings. These muscles are involved in

hip extension which only occurs in what we call the pawback. You may not

believe it but you are in essence improving this action to make the runner

faster.

Your comment in regard to horizontal forces was inappropriate. Yet you mention

it in

the first step out of the blocks but where else do you use it?

You allude to the fact that I must do a lot of guessing in my work. It once

again shows how you draw false conclusions because once again you do not

understand what is being said.

I deal with the body of the runner, his muscles, limbs and joint actions.

These are the things that can be changed, improved, modified and so on. I

don't get hung up on how much force is produced on landing. I am more

interested in the return of the force to produce horizontal speed. So why

should I bother measuring forces all the time? I know how to produce more

force on the landing and this is what we work on.

If you are truly interested in measuring force as I presume you are from

your comments, why don't you also measure the force and/or speed of the arm

and leg actions in both forward and backward directions. These are the

forces I would like to know something about. I don't know of any system

out there that is capable of all of these measurements while running on the

track. Yet you presume I'm not interested in force.

There is no need to continue

Yessis, PhD

Professor Emeritus, CSUF

President, Sports Training Inc.

www.DrYessis.com <http://www.dryessis.com/>

CA, USA

[Guest guest]

Hi Doug!

In a message dated 3/26/2009 11:25:19 A.M. Central America Standard ,

dfairbanks92@... writes:

I do not sprint with this mindset anymore and have had no issues

Here are a few more references from the book that somehow got me back into

this debate in the first place: Charlie Francis noted the following in Key

Concepts: Elite Series

" So then what are the proper coaching cues for top-speed phase?

Just step over and step down. Don't over-lift and don't paw back- otherwise

your butt will be dragging. "

Charlie also notes the following:

" Like professional pianists, who simply know where the keys are, the great

sprinters are going too fast to dwell on technique. "

These observations appear to corroborate your own insights.

Ken Jakalski

Lisle High School

Lisle, IL USA

[Guest guest]

The following two statements by :

" If they understand the physics of motion then they never would publish such

conclusions. I know from life experience (I'm 71) that the great majority of

people haven't a clue as to the laws of physics " and " Candidly, I am quite

ignorant of the studies in this area "

Plus this statement by Henk,

" Never let technology or scientific " quackery " like presented in the last posts

about mechanics of sprint get in the way of common sense and experience "

and finally this statement by Dr. Yessis,

" Answering a question by citing a study is not answering the question. It only

adds more " facts " to the issue that tend to confuse the issue, not clarify it "

seem to summarize the analytical approach of one side to this discussion. I

prefer Ken’s approach.

Jon Haddan

Irvine, CA

[Guest guest]

Ken,

'Like professional pianists, who simply know where the keys are, the great

sprinters are going too fast to dwell on technique.' These observations appear

to corroborate your own insights. "

I find this a little hard to swallow. The great sprinters must dwell on

technique. In the book, " Death in the Locker Room " (I don't have the authorst

name because I'm at home and the book is at work) it was noted that 80% athletic

accomplishment came from skill development and acquisition. Whether or not a

person should focus on the paw back or just stepping over the calf isn't much of

my cocern; if a person improves their speed using either technique then it is a

success. But a top level sprinter must focus on technique utilzing the paw back

or not. Sprinting is a skill just like all other athletic movements. A top level

powerlifter, wrestler, thrower etc. must focus on skill or else they will not

reach their highest potential.

There are top level sprinters who use slightly different techniques while

sprinting. Some paw back while some focus on stepping over and driving. This can

be dependent on different areas of strength and power. The fact of the matter is

that teaching technique sans the paw back or not is incredibly important

througout an athete,s career and life.

Even top level sprinters still focus on technique.

Casey Gallagher CSCS

Snohomish, WA USA

>

> Hi Doug!

>

> In a message dated 3/26/2009 11:25:19 A.M. Central America Standard ,

> dfairbanks92@... writes:

>

> I do not sprint with this mindset anymore and have had no issues

>

> Here are a few more references from the book that somehow got me back into

> this debate in the first place: Charlie Francis noted the following in Key

> Concepts: Elite Series

>

>

> " So then what are the proper coaching cues for top-speed phase?

> Just step over and step down. Don't over-lift and don't paw back- otherwise

> your butt will be dragging. "

> Charlie also notes the following:

> " Like professional pianists, who simply know where the keys are, the great

> sprinters are going too fast to dwell on technique. "

> These observations appear to corroborate your own insights.

>

> Ken Jakalski

> Lisle High School

> Lisle, IL USA

>

[Guest guest]

Below a citation from Charlie Francis; but where is the scientific backup by

force platform or video analysis to conform these statements ?

Do we really need to call the weather station to see if the sun is out

today? Why complicate matters? I agree with Charlie: if you can think about

technique, you are running too slow..

Henk Kraaijenhof

Amstelveen

Holland

=====================

Here are a few more references from the book that somehow got me back into

this debate in the first place: Charlie Francis noted the following in Key

Concepts: Elite Series

" So then what are the proper coaching cues for top-speed phase?

Just step over and step down. Don't over-lift and don't paw back- otherwise

your butt will be dragging. "

Charlie also notes the following:

" Like professional pianists, who simply know where the keys are, the great

sprinters are going too fast to dwell on technique. "

These observations appear to corroborate your own insights.

Ken Jakalski

Lisle High School

Lisle, IL USA

[Guest guest]

Hi Casey!

Your response to the Charlie Francis quote: 'Like professional pianists, who

simply know where the keys are, the great sprinters are going too fast to

dwell on technique.'

>>I find this a little hard to swallow. The great sprinters must dwell on

technique.>>

Ken writes:

Define technique. If technique means something like correct recovery of

the swinging leg, that swing time must be in the range of 0.344, and if

technique is indeed somehow influencing that swing time, we'd be hard pressed

to

explain why athletes running at 11 m/s are recovering the leg just three

hundredths of a second faster than an athlete running at a meager 6.2 m/s. (JAP

2000)

>> In the book, " Death in the Locker Room " (I don't have the authors name

because I'm at home and the book is at work) it was noted that 80% athletic

accomplishment came from skill development and acquisition.>>

Ken writes:

No disagreement with the important of technique in specific events. The

extension of technique to high speed running is different.

>>Whether or not a person should focus on the paw back or just stepping over

the calf isn't much of my concern; if a person improves their speed using

either technique then it is a success.>>

Ken writes:

But how do we know that the improvement in speed was a result of any of

those techniques, especially in my case, where I've analyzed hundreds of high

school athletes who, after years of consistent practice in specific drills for

speed, improved performances yet revealed no evidence that they were actually

performing the skills that I taught (ie. pawback)? I suppose it’s not

necessary to assess the presence of what we've been training an athlete to do

as

long as his or her time improves, but what if I could determine with a high

level of confidence that the drills I was taking time teaching were not

necessary? I could then focus on other things. Further, what if I also had

evidence

that the drills for speed I was teaching were actually detrimental to speed

improvements?

For example, attempts to alter ‘form’ are especially bad to try during the

brief contact periods when forces are so high. Artificially trying to

shorten them (and I had drills to accomplish this) actually increases the

metabolic

power requirements at any given speed, and prolonging them is not possible

without messing up leg springs.

As was pointed out at our ’02 seminar: horses, big birds and virtually

anything that runs and has been studied conforms to general mechanical and

energetic patterns, and all the experiments implementing deviations from those

patterns indicate that function is compromised once we start messing with these

mechanics.

For example, Charlie Francis noted the following: " There is a significant

difference among athletes, but I have learned to take a very conservative

approach in deciding whether an idiosyncrasy should be changed or left alone.

In

some athletes, there will be differences in the way their leg musculature is

attached to the skeleton. This results in different lines of pull.

In absolute terms, each of your athletes has differences in body segment

lengths, location of muscle attachments, etc. If the athlete is running well,

you assume that the physical idiosyncrasy is not a factor.

If the athlete is able to run fast, smoothly and has no physical complaints,

I would leave the idiosyncrasy in tact. Ben ’s left knee carries out

to the side when he runs. So what? If an idiosyncrasy does not impact on

performance, don’t tamper with it. Olympic gold medalist Ashford

tilts

over to the left. That too, is not a limiting factor-—for her! "

And these observations confirm something Mel once said to me: “Does " form "

really impact on the skill of sprinting, or is a sprinter’s “form†simply

his or her unique way of interpreting the skill? What we perceive as

mechanical " flaws " might very well be ways the athlete is compensating for

asymmetries we simply can't identify.â€

And Owen reached a similar conclusion regarding the failure of

coaches to change the ‘form’ of the athletes they are training. “The

continued

flow of negative results does make one wonder whether the majority of runners

adopt running styles which - although they may look quite unusual - are

relatively efficient, given their anthropometric and physiological

constraints. "

We can look to the penguin research of Rodger Kram for further confirmation

of this concept. To the layman, the penguin’s waddle looks highly

inefficient, but that is not the case. For penguins, the percentage of energy

retained during one stride (recovery rate) is among the highest of any

terrestrial

animal. The rocking motion of penguins helps raise their center of mass.

Without this movement, the penguin’s muscles would have to make up that work.

In

other words, I believe Mel made an excellent point.

>>>But a top level sprinter must focus on technique utilizing the paw back or

not. Sprinting is a skill just like all other athletic movements. A top level

powerlifter, wrestler, thrower etc. must focus on skill or else they will

not reach their highest potential.>>>

Ken writes:

This is where I will disagree. High speed sprinting is not like all other

athletic movements.

>>There are top level sprinters who use slightly different techniques while

sprinting.>>

***

And do any of these techniques require coaching cues or drills taught in

isolation? I think Dan s offered one of the best perspectives on this

issue: “technique†means different things to different coaches. Dan

believes

that technique training equals specific training, and I agree. He goes on to

note that the more specific the training is to the event/task/skill, the

more technical is the training.

Dr. Mike Young noted the following: “Sprint drills do not in and of

themselves develop proper sprint mechanics and may in fact be detrimental.

Sprint

drills can however provide an opportunity to teach cues that can be used in

full speed sprinting, or create desired sensations which may carry over to full

speed sprinting. These benefits, however, are contingent on the manner in

which the sprint drills are performed. Sprint drills may also be used to

develop

certain physical capacities or warm up the athlete.â€

>>>Some paw back while some focus on stepping over and driving.>>

Ken writes:

Some might claim they are pawing back, but I've seen no evidence of its

existence in athletes that I've trained in the technique. And as I've noted

throughout the discussion, the pawback is at odds with the spring mass model.

So

maybe I was simply wasting time cueing a mechanic that was not occurring in

the first place.

>>This can be dependent on different areas of strength and power. The fact of

the matter is that teaching technique sans the paw back or not is incredibly

important througout an athete,s career and life.>>

Ken writes:

I very much agree--if we can come to agreement regarding the essential

'teachable' techniques for high speed running.

>>Even top level sprinters still focus on technique.>>

Ken writes:

Dan s also said the following: " I teach mechanics by having my

athletes run fast. " If that’s what we mean by technique, I agree. " But

that point

will continue to rub some colleagues the wrong way. Yet many elite coaches

appear to be taking a more conservative approach relative to the teaching of

technique.

Dr. Mike Young noted the following:

“I think technical development is fair game in almost all instances. Don't

take this to mean I over-coach sprint mechanics. In fact, most of my athletes

will complete a sprint workout and never hear a word about mechanics.

Others might be able to go the entire year without hearing anything. Those that

are running lazy or those who have come to me with what I perceive to be poor

mechanics, however, might get 2-3 feedback comments in a workout.â€

Again, on these issues, it's not that I've taken a different stance because

I'm trying to present a 'new' sprint mechanics paradigm. I'm selling nothing

and have no secret formula for success. I know what I used to do, and what I

now do. And I have ample data from 'both worlds " with which to formulate a

conclusion. For the majority of the first half of my coaching career, I

enthusiastically endorsed and practiced and championed the majority of drills,

cues, and interventions that many still consider essential technique. That's

changed for me as a result of the unique learning opportunities I've been

afforded since the paralympians came to Lisle and upset my comfortable

'mechanics

applecart' over ten years ago. And if you upset the apple cartupset my

comfortable 'mechanics applecart' over ten years ago.

Ken Jakalski

Lisle High School

Lisle, IL USA

[Guest guest]

Doug,

As someone who competed in powerlifting for over ten years (a motorcycle

accident and change in life philosophy cut my career short) and followed the

West Side philosophy, I would have to strongly disagree with you. During

conjugate days, technique is of primary focus. Weight is light and moved at a

different speed (faster) than during a competition but technique and motor

patterns are focused and developed. During max effort days, correct movement

patterns were still a focus. Louie himself has gone to great lengths discussing

his opinion on proper bar placement, foot placement and so on.

A lift might be different than a full range of motion competition lift but that

is to develop strength for different aspects of the lift. For example, rack

lockouts were used to aid in sticking points at the top part of a bench as well

as develop triceps strength in the function of the movement. Good mornings are

used to develop strength throughout the core, especially the spinal erectors and

hamstrings. This is good example of how a person can perform a particular skill

and still improve their motor patterns for another; utilizing good mornings in

order to develop squatting skill. Louie advocats rarely using the competition

lifts at maximum effort during training. For example, don't use a full range of

motion bench press in order to get stronger at the bench. Train the different

positions of the bench press, especially where a person is weakest.

I agree that in non-sprint sports athletes often won't use pure sprint

mechanics. However, certain mechanics can be utilized or adapted to help that

particular athlete for a particular sport - acceleration mechanics for a

basketball player and football player or slight alteration in max velocity

mechanics to simulate running in contact with another player for a soccer

(football) player.

The use of a baseball swing was an analogy to state that just performing the

skill will not, in general, does not develop proper movement patterns for that

skill. Sprinting is included in that skil development. We all know how to sprint

yet techniques and velocities differ from person to person. Why? Muscular power

and strength play a vital role in sprint times but so does technique. Comparing

bat swing mechanics and sprint mechanics is comparing apples to oranges but that

was not the intent of my post.

Casey Gallagher CSCS

Snohomish WA USA

>

> Casey,

>

> When I think of non-track athletes I think of them as skilled in there sport

and sprint speed is but a small and very small fraction of what improves there

performance. We know that so many of them dont ever reach top end speed in

there respected sports, like a football running back, baseball position player

as well as soccer players. Even if the soccer player midfielder gets to top

speed it is still pretty rare and with a constant anticipation of stopping and

decelrating occurring at any moment makes it awful difficult to get into top

speed body posture like a 100 meter sprinter.

>

> I agree with you that learning a new skill the athlete can look clumsy and

that it maybe adds some crosstraining benefit or dynamic warm up, but to say

that it will guarantee improvements in speed is hard for me to buy with my

experience with again non-track athletes. The limitations they have are not

enough sprint work and or training with too long of distances too often. What I

always need to remember is to have the athletes trust and confidence maintained

and if I can not prove to them that all this techinique work is improving there

speed by yesterday then I risk losing there confidence, so I stick to what I can

guarantee. The difference in your example of the baseball player focusing on

his batting is that sprinting has ground reaction forces from gravity and

swinging a bat doesnt, that makes for a bad comparison in my opinion.

>

> In response to your squatting and deadlifting comparison with sprinting I

would ask his question. For example Westside Barbell, as an outsider who has

not been there but has attended lectures and seen video, I feel that most of the

improvements made week in and week out with there system is on different

strength qualities, variations in exercises etc. They dont seem to be teaching

technique as a main focus and like you said different bodies display variations

in technique from what might be consideredd textbook form. Just my opinion,

thanks.

>

> Doug Fairbanks

> Boston,MA

[Guest guest]

The below seems relevant from Bud Charniga:

" " Famous Soviet era Biomechanist D. Donskoi wrote more than 50 years ago that an

athlete's attention to the details of an exercise or sport movement decrease as

technique improves. " Depending on the level of technical mastery many of the

features and details of a movement will no longer fall under volitional control

and management, but instead, become automated " (D. Donskoi, 1971)

Consider this comment from Tyson Gay after he ran a 9.69 100 meters; " Relaxation

is the key to success in track and field… (Saturday) I totally relaxed and let

the time come. " It is essentially impossible to relax, run at maximum speed, and

at the same time to focus on the " core " in order to " stabilize ankles, knees "

and other parts of the body. " "

=================

Carruthers

Wakefield, UK

[Guest guest]

Hi Doug!

You noted the following in your last post:

" I doubt that there is any way to 'reconcile' their description with my

statement of the laws of physics. If their observations lead to conclusions that

don't agree with the laws of physics, then I'd say they are incorrect in their

observation. This is more than likely due a lack of understanding of

physics. If they understand the physics of motion then they never would publish

such

conclusions. I know from life experience (I'm 71) that the great majority of

people haven't a clue as to the laws of physics. "

It's regrettable that there is still some confusion relative to the spring

mass model. Tom McMahon has long been held in the highest regard in the

locomotion community. For someone who has published as many scientific papers

in

peer reviewed journals as he has, I doubt that he is guilty of " incorrect

observations " or a " lack of understanding of physics. " The issue is still one

of misunderstanding over the spring mass model itself.

Check out the following website dedicated to Tom's body of work:

_http://www.thomasmcmahon.net/_ (http://www.thomasmcmahon.net/)

Ken Jakalski

Lisle High School

Lisle, IL USA

[Guest guest]

When we think of the importance of technique in sprinting as being similar to

other sports, we need to take a look at the results of technique changes. 

When Parry O’ came up with the glide, it revolutionized the shot put. 

The same is true for the Fosbury flop, the jump shot in basketball, and the

underwater dolphin kick in swimming.  These technique changes made big

differences in performance and were universally adopted.  The same simply

cannot be said for technique in sprinting.  Runners today look pretty much the

same as runners from generations ago. 

I can be an elite sprinting running toes in (Bob ),  toes out (

Gaitlin) or toes straight (Borzov), but I cannot be an elite shot putter with

pre-glide form and I can’t even play basketball with a set shot.   

As far as the need for the eagle eye of the skilled coach to detect minor

imperfections in sprint technique, it should be noted that all of the above

technique changes came about by individual athletes tinkering around and not by

elite coaches. 

This isn’t to say that the start doesn’t have to be taught or that some

people have such bad form that some technique work is necessary, but the promise

of speed improvement by an emphasis on technique seems misplaced.

The simple fact is that for all the talk about technique, I am not sure there is

much evidence that it is a big part of high school, collegiate or professional

training.  A few verbal cues and some basic warmup drills is about all I have

ever observed in Southern California.  I will concede that in Europe technique

seems to get much more emphasis. 

The only place I have seen a big emphasis on technique is the weekend training

of slow football players by the so-called speed gurus.  Every area has them,

they are very expensive, and they all allegedly can work wonders. I haven’t

seen it happen and I know a number of parents who sent their kids to these guys.

Jon Haddan

Irvine, CA

[Guest guest]

In a message dated 3/31/2009 4:28:08 A.M. Central America Standard T,

jon_haddan@... writes:

it should be noted that all of the above technique changes came about by

individual athletes tinkering around and not by elite coaches.

The above reminds me of a discussion I had with Dick Railsback a few years

back. Dick talked how the legendary pole vaulters, at the dawn of the

fiberglass poles, were constantly tinkering and learning as they went along, as

were

their coaches. I think it was the late American record holder Pennel

who mentioned to Dick about taping his top hand to the pole to keep it from

sliding down.

Ken Jakalski

Lisle HS

Lisle, IL USA

[Guest guest]

Hi

apologies for the delay in return on this email, but other factors have

intervened.

You say in the email

" Without actually measuring the vertical and horizontal force vectors, it

consistent with the laws of physics, that, at _constant_ speed the

horizontal vector would be small, and the vertical vector larger because the

body weight of even a light runner should dwarf the horizontal vector. "

1. In a number of post by Barry and Ken and in extracts posted from a number

of locomotion studies including the Weyand study these forces were measured

and the vertical force component does dwarf the horizontal force component

as you say this would be apparent from body weight of even a light athlete.

2. If the horizontal force component is small relative to the vertical, then

the law of diminishing returns would apply sooner to the horizontal force

component generation. Also in order to resist fatigue the runner needs to

be able to constantly hold and then amortise as much of this vertical

component force in spring like fashion as possible. Since this force is

quite large as it is applied very rapidly (ground contact times very small

less than 0.1 secs, means absorb and return the body mass accelerating due

to gravity in that time) the work of the muscles in a. holding the athlete

up and b. returning these forces in the vertical direction (or along the

line of the runners body) is where the training should focus. Strengthening

this ability seems to me to be a good part of the training. By training

this strength with low repetitions the athlete will keep muscular strength

high with hypertrophy to a minimum, as it would be apparent (to me at

least) that the less force that the athlete has to deal with the slower the

fatigue sets in and the greater the ability of the muscle system will be to

return spring energy to move the athlete faster.

The following quote from Barry Ross in an email to me sums up this ground

reaction force quite nicely

" Faster runners apply greater support force in shorter times then slower

runners. The effect on the faster runner is shorter ground contact times

than slower runners. Effective support force is force applied by the runner

that exceeds GRF. Effective support force, averaged over ground contact time

increases in direct proportion to running speed. "

In response to your question about height and the vertical versus horizontal

a comment again from Barry Ross is

" One item of note is that faster runners, generally, do not elevate as much

at top speeds as slower runners. Their effective force allows them to travel

at a higher rate of speed, thus stride length increases without need of

additional elevation. "

However in my opinion this does still not negate the relative force

components namely, big vertical and small horizontal but points to an

efficiency of running by faster athletes in returning the forces that result

from the very small ground contact times.

For me I'm sill more interested in the acceleration phase of runners as this

seems most applicable to a team sport like rugby where runners will very

rarely get more than 30m in a sprint with out having to change direction,

break through a tackle or similar. But what I am trying to understand is

how to best train players to develop this first 5 step acceleration. And

again I think that applying the force in line with the body will best

generate this force, how to train this I guess would be another debate.

Regards

Nick Tatalias

Johannesburg

South Africa.

[Guest guest]

> And

> again I think that applying the force in line with the body will best

> generate this force, how to train this I guess would be another

> debate.

If the body is leaning forward, yes, if not, then it will not produce

_any_ forward accelerative force because the force will be directed

straight downward accelerating the body vertically. This does not

happen, significantly, with rapid runners. I'm told the vertical

movement of fast runners is about 4 cm, average. This indicates very

little vertical force over the amount necessary to support the weight

of the runner's body. I say again, the _only_ force that can

accelerate the body forward is backward force at the foot contact

patch. This will cause the body to move forward.

A major problem with rapid acceleration is traction. When horizontal

force exceeds that allowed by the materials coefficient of friction,

the feet slip. This is why shoes are typically cleated to allow them

to physically dig into the playing surface. Thereby they exceed the

normal coefficient of friction for the materials involved and greater

acceleration is possible. Even with cleats, a powerful athlete

attempting maximum acceleration, can slip, digging out divots from the

playing surface.

Fair winds and happy bytes,

Dave Flory,

Flower Mound, TX, U.S.A.

--

Speak softly, study Aikido, & you won't need to carry a big stick!