Re: Pistorius - a considerable advantage?

[Guest guest]

Relevant to previous discussions on the list:

http://www.iaaf.org/aboutiaaf/news/newsid=44917.html

Monte-Carlo - The IAAF is pleased to announce that the Court of

Arbitration for Sport ( " CAS " ) this afternoon has declared that

Pistorius (RSA) is eligible to compete in competitions under IAAF

Rules.

The decision is a culmination of a process in which Mr Pistorius and

the IAAF have co-operated together to resolve the issue of whether

the " Cheetah " prostheses Mr Pistorius wears give him an advantage in

competition. While the IAAF has been keen to give Mr Pistorius every

opportunity to participate in its events, it had to deal with some

concerns that he may be gaining an unfair advantage.

As a result, in November 2007, Mr Pistorius and the IAAF voluntarily

engaged in a process of testing under the auspices of Professor

Brüggemann at the Sportshochschule in Cologne. Professor Brüggemann

provided his report in December 2007. Following this report, the

IAAF Council took the decision that, because Professor Brüggemann had

found that the prostheses gave Mr Pistorius an advantage, he was not

eligible to compete.

Mr Pistorius referred the matter to CAS where further expert advice

was obtained and reviewed. The hearing before CAS was conducted in

an open, constructive and co-operative fashion with all parties keen

to establish the truth.

The CAS Panel has today delivered its decision. It has decided that,

at the moment, not enough is known scientifically to be able to prove

that Mr Pistorius obtains an advantage from the use of the

prostheses. Consequently, it has cleared him to run.

President Lamine Diack has made the following comment:

" The IAAF accepts the decision of CAS and will be welcomed

wherever he competes this summer. He is an inspirational man and we

look forward to admiring his achievements in the future. "

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

Carruthers

Wakefield, UK

> The below was recently published on the IAAF website:

>

> Pistorius - Independent Scientific study concludes that

cheetah

> prosthetics offer clear mechanical advantages

> Monday 14 January 2008

>

> Monte Carlo - The IAAF has received the results of an independent

> scientific study carried out by Professor Brüggemann at the

> German Sport University in Cologne. This study made a biomechanical

> and physiological analysis of long sprint running by a double

> transtibial amputee athlete Pistorius (RSA) using " cheetah "

> prosthetics, and also compared this athlete with five able-bodied

> athletes who are capable of similar levels of performance at 400m.

>

> The tests, which took place on Monday 12 and Tuesday 13 November in

> the Institute of Biomechanics and Orthopaedics, were initiated by

the

> IAAF with the approval and participation of in order to see

> whether the prosthetics used by him should be considered as

technical

> aids which give him an advantage over other athletes not using them,

> in contravention of IAAF competition rule 144.2.*

>

> The objective results of this study are that:

>

> - Pistorius was able to run with his prosthetic blades at the same

> speed as the able-bodied sprinters with about 25% less energy

> expenditure. As soon as a given speed is reached, running with the

> prosthetics needs less additional energy than running with natural

> limbs.

>

> - Once the physiological potential of Pistorius and the able-

> bodied control athletes had been estimated, using three different

> methods, it is clear that Pistorius' potential was not higher than

> that of the controls, even though their performance results were

> similar.

>

> - The biomechanical analysis demonstrated major differences in the

> sprint mechanics used by a below-knee amputee using prosthetics when

> compared to athletes with natural legs. The maximum vertical ground

> reaction forces and the vertical impulses are different in a highly

> significant way and the amount of energy return of the prosthetic

> blade have never been reported for a human muscle driven ankle joint

> in sprint running.

>

> - The positive work, or returned energy, from the prosthetic blade

is

> close to three times higher than with the human ankle joint in

> maximum sprinting.

>

> - The energy loss in the prosthetic blade was measured at 9.3%

during

> the stance phase while the average energy loss in the ankle joint of

> the able bodied control athletes was measured at 41.4%. This means

> that the mechanical advantage of the blade in relation to the

healthy

> ankle joint of an able bodied athlete is higher than 30%.

>

> It is evident that an athlete using the Cheetah prosthetic is able

to

> run at the same speed as able bodied athletes with lower energy

> consumption. Running with prosthetic blades leads to less vertical

> motion combined with less mechanical work for lifting the body. As

> well as this, the energy loss in the blade is significantly lower

> than in the human ankle joints in sprinting at maximum speed. An

> athlete using this prosthetic blade has a demonstrable mechanical

> advantage (more than 30%) when compared to someone not using the

> blade.

>

> IAAF Council has been able to review the full report and has decided

> that the prosthetic blades known as " cheetahs " should be considered

> as technical aids in clear contravention of IAAF Rule 144.2. As a

> result, Pistorius is not eligible to compete in competitions

> organised under IAAF Rules.

>

> Note for editors concerning test procedures and parameters:

>

> - Analysis was carried out by a team of more than 10 scientists,

> including staff from the physiology laboratory of Professor J.

Mester

> (Institute of Training Science and Sport Informatics).

>

> - 12 high speed cameras (250 frames per second) were used to record

> 3D kinematics, with another 4 highspeed cameras to observe sagittal

> plane motion

>

> - Force platforms were used to record ground reaction forces and

> point of force application

>

> - Athletes ran the 400m test with a K4 mask to record max VO2. VO2

> testing was also carried out in the laboratory (Wingate and Ramp

> Test) on static bicycles. Blood lactate records were taken regularly

>

> - A 3D scanner was used to record body mass and anthropometric

> measures of all the control athletes

>

> - The prosthetics were also subjected to material testing

>

> * IAAF Rule 144.2 extract

>

> Relates to the use of " technical aids " during competition

>

> =============================

> Carruthers

> Wakefield, UK

>

[Guest guest]

Ken Jakalski kindly sent me the below article:

http://www.rice.edu/nationalmedia/news051608oscar.shtml

Houston, TX -- (May 16, 2008) -- A world-renowned team of experts in

biomechanics and physiology from six universities, led by Professor

Hugh Herr of the Massachusetts Institute of Technology's Media Lab,

refutes scientific claims that the prostheses worn by

Pistorius, a 21-year-old South African bilateral amputee track

athlete, provide him with an unfair advantage in the 400-meter race.

Their conclusions were based on data collected at the Rice University

Locomotion Laboratory, under the direction of Professor Weyand.

Pistorius hopes to run in the 400-meter race at the Beijing Olympics

this summer.

Based on the team's findings, the Court of Arbitration for Sport

(CAS) in Lausanne, Switzerland, has ruled that Pistorius is eligible

to participate in International Association of Athletics Federations

(IAAF) sanctioned competitions. If he qualifies for the 2008 Beijing

games, Pistorius would be the first disabled athlete ever to run

against able-bodied athletes in an Olympic event.

The team's findings were presented to the CAS April 29-30 by Herr and

Professor Rodger Kram of the University of Colorado at Boulder, and

provided the foundation for Pistorius' appeal to overturn the IAAF

decision that previously banned him from running against able-bodied

athletes in races that are governed by IAAF rules. The team's

findings were presented at the CAS, where Pistorius was represented

by the international law firm of Dewey & LeBoeuf on a pro-bono basis.

In addition to Herr, Weyand and Kram, the panel of experts included

Professor Bundle from the University of Wyoming, an expert in

the energetics and mechanics of sprinting performance; Craig McGowan,

from the University of

Texas at Austin, a leading authority on muscle, tendon and joint

mechanics;

Alena Grabowski, from the Massachusetts Institute of Technology, an

expert in human locomotor energetics and biomechanics; and Jean-

Benoît Morin from the University of Saint-Etienne, an expert in the

mechanics of human running performance.

None received compensation for their research or participation in the

hearing. The authors plan to submit the study to a peer-reviewed

journal now that the legal case has been settled.

The scientific team was asked to evaluate the IAAF's initial claim

that the Cheetah Flex-Foot prostheses (J-shaped, high-performance

prostheses used for running) worn by Pistorius give him an advantage

over able-bodied runners. The team concluded that the scientific

evidence put forth by the IAAF investigation to ban Pistorius was

fundamentally flawed. " While an athlete's performance in sprints of

very short duration is determined almost entirely by mechanical

factors, in races of longer duration, such as the 400m, performance

depends on both mechanical and metabolic factors, " said Herr, a

bilateral amputee who heads the MIT Media Lab's Biomechatronics

research group.

Based on this performance link, the scientists refuted the IAAF

findings on two major points: the speed-duration relationship and

rates of metabolic energy expenditure.

Specifically, the scientists concluded that:

• Pistorius' ability to maintain speed over the course of longer

sprints--his speed-duration relationship--is essentially identical to

that of able-bodied runners, indicating that he fatigues in the same

manner as able-bodied sprinters.

• Pistorius' rates of metabolic energy expenditure do not differ

from elite non-amputee runners. In particular, he has nearly the same

running economy, or rate of oxygen consumption at submaximal speeds,

and a similar maximal rate of oxygen consumption as elite non-amputee

runners.

" Based on the data collected at Rice, the blades do not confer an

enhanced ability to hold speed over a 400m race, " Weyand said. " Nor

does our research support the IAAF's claims of how the blades provide

some sort of mechanical advantage for sprinting. "

" The study commissioned by the IAAF claimed that Pistorius has a 25

percent energetic advantage at 400m race speeds. That claim is

specious because anaerobic energy supply cannot be quantified, " Kram

said.

In summary, the team of experts unanimously concluded that the IAAF

allegations were not scientifically valid.

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

Carruthers

Wakefield, UK

[Guest guest]

Hi !

I'm sure an op-ed appearing on a university website is not the way any of

these researchers would like to have their findings presented to the general

public. In fairness, this may have been an issue with the Cologne group's

initial findings as well.

I think it's best to wait for all specifics of the study, which I'm sure

will submitted for publication.

Regarding fatigue as an issue: I'm only conjecturing here, but it seems as

if the thrust from some of the initial reports centered on the notion that

Pistorius was running 'negative' splits in the 400, and that this suggested his

Cheetahs were in some way (weight, design, or whatever) reducing his

metabolic cost.

So how to explain these 'negative' splits? Pistorius's carbon fiber

Cheetahs can mimic muscle-tendon function once up to speed, but acceleration

is an

entirely different matter. When Tony Volpentest ran here in Lisle back in

'97, what struck me is that he was a surprisingly poor starter. In the 100

meter dash, he was beaten by three runners from a Masters field I had

assembled to race against him. However, in the 200, the situation was

completely

different. Once he was up to speed, he caught the field, blew past them, and

ended up with a 22.94, which at that time was an 'unofficial' world paralympic

record at that distance.

The problem, and this has been noted by other researchers not directly

involved in the testing, is that these carbon fiber blades are not 'adjustable'

to

the demands of acceleration. The blades can't 'mimic' the mechanics of

acceleration, and with no ankle and calf, these below-the-knee amputees can't

" push-off, " and this means less acceleration of their center of mass.

Ken Jakalski

Lisle High School

Lisle, Illinois USA

[Guest guest]

> Really? The blades are NOT more elastic and therefore do NOT

store energy

> more efficiently leading to more economic energy expenditure?

How does that

> relate to the construction and properties of the blades? Even more

> interesting; how does that reflect on DR Weyand's hypothesis and

proofs of elastic

> rebound facilitation of RFD in high speed running.

>

> Without (admittedly) reading the entire test data and analysis,

these

> conclusions seem " specious " to me on their face value regarding

application to the

> question and contradictory to previous assertions by the scientists

in related

> issues of locomotion.

****

Here are some of the previous statements regarding this topic:

http://au.news.yahoo.com/070717/2/13zgn.html

" " The prosthetic legs that double-amputee sprinter Pistorius

races with provide less air resistance than normal legs, the IAAF has

said.

Davies said the initial research also showed that the way Pistorius

distributed energy was virtually the opposite to able-bodied runners.

And unlike able-bodied runners, Pistorius was faster at the end of

the race instead of the beginning.

Pistorius was able to run with his prosthetic blades at the same

speed as the able-bodied sprinters with about 25 percent less energy

expenditure, " the report concluded.

FURTHER TESTS

The report said the returned energy from the prosthetic blades, known

as " cheetahs " , was close to three times higher than the ankle joint.

" The mechanical advantage of the blade in relation to the healthy

ankle joint of an able-bodied athlete is higher than 30 percent, " it

added.

" It is evident that an athlete using the Cheetah prosthetic is able

to run at the same speed as able bodied athletes with lower energy

consumption. "

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

Carruthers

Wakefield, UK

[Guest guest]

On a personal note, I am very pleased for , its not just his Olympic

performance that is at stake, but also his participation in all IAAF events

including the South African national competitions and other IAAF events, so

good luck to . Practically has not qualified to run in the 400m

event yet and would only go to Beijing as a relay alternate, unless he

qualifies shortly.

I'd love also to read the evidence presented in full, until then I will with

hold my thoughts.

Best Regards

Nick Tatalias

Johannesburg

South Africa

2008/5/17 Casler :

> Ken Jakalski kindly sent me the below article:

>

> The scientific team was asked to evaluate the IAAF's initial claim

> that the Cheetah Flex-Foot prostheses (J-shaped, high-performance

> prostheses used for running) worn by Pistorius give him an advantage

> over able-bodied runners. The team concluded that the scientific

> evidence put forth by the IAAF investigation to ban Pistorius was

> fundamentally flawed. " While an athlete's performance in sprints of

> very short duration is determined almost entirely by mechanical

> factors, in races of longer duration, such as the 400m, performance

> depends on both mechanical and metabolic factors, " said Herr, a

> bilateral amputee who heads the MIT Media Lab's Biomechatronics

> research group.

>

> Based on this performance link, the scientists refuted the IAAF

> findings on two major points: the speed-duration relationship and

> rates of metabolic energy expenditure.

>

> Specifically, the scientists concluded that:

>

> . Pistorius' ability to maintain speed over the course of longer

> sprints--his speed-duration relationship--is essentially identical to

> that of able-bodied runners, indicating that he fatigues in the same

> manner as able-bodied sprinters.

>

> . Pistorius' rates of metabolic energy expenditure do not differ

> from elite non-amputee runners. In particular, he has nearly the same

> running economy, or rate of oxygen consumption at submaximal speeds,

> and a similar maximal rate of oxygen consumption as elite non-amputee

> runners.

>

> Casler writes:

>

> While I am not informed enough to have an opinion on the " equality " over

> all

> competitors, I might wonder or question the assertion of " metabolic "

> advantage.

>

> I, for over 20 years have used " stair climbing " as a great Cardio

> Stimulating activity, and regularly do so.

>

> During this period I have explored many climbing and descending experiments

>

> to compete with myself and become faster.

>

> It didn't take too long for me to find that climbing on my " toes " caused a

> greater blood flow to my calves. This then when viewed logically suggested

> several things:

>

> 1) The blood flow to the calves was significant.

> 2) The distance the blood was pumped was far greater from the heart, and

> surely offered greater stress

> 3) The circulatory efficiency of supplying blood both TO and FROM the

> calves

> was a greater stress due to the " Cul de Sac " system.

>

> In light of this, I adjusted my form to step deep into the step itself and

> land on the heel, reducing calf involvement. This then reduced blood

> requirement for the area. Additionally I pushed off with the heel, causing

> even greater hip and ham involvement.

>

> The proximity of the glutes and hams to the heart to both supply and return

>

> blood was far less stressful and my times steadily improved.

>

> Now while this certainly doesn't suggest that metabolic requirements are

> small, it does offer an interesting question as to if the shorter and more

> direct blood flow can offer metabolic advantage.

>

> While I might suggest it " does " , I might also say that I can see no viable

> method of establishing the scope of the advantage, considering the

> disadvantages contained in the disability itself.

>

> However, it is interesting none the less.

>

> I think this will be one " large story " of the upcoming OLYMPICS. Good or

> Bad, the Press will love this.

>

> Regards,

>

> Casler

> TRI-VECTOR 3-D Force Systems

> Century City, CA

>

>

>

[Guest guest]

<getting up on the soap box>

Just my uneducated opinions here.... I take a simplistic view of this.

I find this whole activity of measuring the blade's mechanical

advantage interesting but pointless. Measurements mechanical and

metabolic advantage should not come into the equation. It should not

be about how good the prosthetic is.

Our thinking has become clouded by our desire to be sensitive to

" non-traditionally-abled " athletes.

At what point in the advanced design of prosthetic devices would an

athlete be disqualified from competing against athletes with more

typical anatomies? How much 'spring' off the block would disqualify

the prosthetic? When there is a 2% advantage? Measured how? Compared

to what - my leg and foot or yours or the 'average' leg and foot? When

the prosthetic catapults the sprinter over the finish line without

having taken a step?

It's almost like having stock cars and formula one's in the same auto

race. " Oh - but they both have the same tires, engines and power

ratings. " Well - sorry - that is not the point. One's a stock car and

ones a formula one. End of discussion.

Pistorius is an amazing athlete. Inspring. But he should compete

against others in his own class of race.

Perhaps we could have several different classes of sprinting

competition (somewhat tongue in check):

" Natural " (no HGH/steroids/drugs/prosthetics)

" Juiced " (any drug you like, no prosthetics)

" Assisted Natural " (no drugs, prosthetics only)

" Natural Open " (no drugs, prosthetics optional)

" Wide Open) (anything goes, HGH, steroids, prosthetics, stilts...)

<descending from soap box>

Jim Lorenz

Los Altos, USA

>

> Relevant to previous discussions on the list:

>

> http://www.iaaf.org/aboutiaaf/news/newsid=44917.html

>

> Monte-Carlo - The IAAF is pleased to announce that the Court of

> Arbitration for Sport ( " CAS " ) this afternoon has declared that

> Pistorius (RSA) is eligible to compete in competitions under IAAF

> Rules.

>

[Guest guest]

Jim,

Nicely written and I agree. Unfortunately this issue is far too

similar to the endless arguments generated when discussing values.

Usually these arguments can never be resolved to everyone's

satisfaction and often not to anyone's. My position is based on

Ockham's razor, " The simplest solution is the best. " , that solution

being that only intact (or prosthesis free) humans compete against

each other. Also simplistic but it does avoid the inevitable debate as

to when does the prosthetic provide an advantage. To me it is obvious

that they're trying to compare as you say, " stock cars and formula

one's in the same auto race. "

I particularly like your athlete classes, except maybe they should be

expanded to include most sports, not just sprinting.

I have tremendous compassion for Pistorious and admiration for what he

has accomplished, but I consider it unreasonable for him to compete

with intact Olympic athletes.

W.G.

Ubermensch Sports Consultancy

San Deigo, CA

> >

> > Relevant to previous discussions on the list:

> >

> > http://www.iaaf.org/aboutiaaf/news/newsid=44917.html

> >

> > Monte-Carlo - The IAAF is pleased to announce that the Court of

> > Arbitration for Sport ( " CAS " ) this afternoon has declared that

> > Pistorius (RSA) is eligible to compete in competitions under IAAF

> > Rules.

> >

>

[Guest guest]

Regarding the recent Pistorius discussions:

This is something paralympic sprinter Tony Volptentest said to reporters

when he ran here in Lisle back in '97. Keep in mind that Tony also is a double

below the knee amputee like Pistorius.

When asked about his 'disability,' Tony noted that poor eyesight might have

once been considered a disability, but glasses and contacts restore

individuals to good vision. He felt his Flex Feet were simply a means for

coming close

to restoring what he did not have, lower legs and feet.

The question both research groups (Cologne and now Rice) have been

considering is whether or not this kind of 'restorative' process goes one step

beyond

in giving the paralympian an unfair competitive advantage over able-bodied

runners. And this has become an issue perhaps because the first reports from

the initial study was that the Cheetah blades were allegedly far more efficient

than a human lower limb.

Again, I ask all interested parties to withhold judgment until the research

team has published its findings. And recent press releases have made it

clear that publishing was the primary reason the research team did the testing

pro bono.

In the meantime, forum members might wish to visit the Rice website to see

some videos of the testing.

_http://www.rice.edu/nationalmedia/news051608oscar.shtml_

(http://www.rice.edu/nationalmedia/news051608oscar.shtml)

Ken Jakalski

Lisle HS

Lisle, Illinois USA

[Guest guest]

I've read everyone else's thoughts- here's my 2 cents for what it's worth:

What percentage of running propulsion comes from the gastrocs and foot? And

how much fatigue in those muscles over the course of 400M is considered normal?

There will never be fatigue in the prostheses, which, all else being equal,

gives him an advantage. I think that his stride length would be less affected

by fatigue(somewhat less, his quads hams and hip musculature are still affected

like any other runner, but less) than an able bodied runner.

And are there engineers out there right now trying to put more bounce into the

next generation of prosthetic in order to better compete. At what point does

the prosthetic provide a " considerable advantage "

Hopefully I'm not out in left field on this- it's an interesting discussion-

Mark , MS, ATC, CSCS

Syracuse, NY, USA

[Guest guest]

Ton van den Bogert, Biomch-L co-moderator recently wrote on the

Biomch-L:

Kirtley wrote:

> However, I also have a feeling that the prostheses are the

> thin end of the wedge that began with Speedo swimsuits. It

> seems to me difficult to block any future device or appliance

> once one is admitted. It is conceptually similar to the use

> of drugs in sport.

Some relevant excerpts from the May 17 article in the NY Times

(www.nytimes.com):

" It's not just about me, " Pistorius said in a telephone interview from

Milan. " It's about the extra opportunity for amputee athletes. "

But on the other hand, it was reported that:

" ...the wording of the ruling appeared to caution against

extrapolation,

clearly stating that it " has absolutely no application to any other

athlete, or other type of prosthetic limb. Each case must be

considered

by the I.A.A.F. on its own merits. " "

So they have been careful and no extra opportunity has really been

created. It may well be that they allowed Pistorius to compete

because

he he is not expected to qualify for the Olympics. The hard decision

has (unfortunately) been avoided but the problem will certainly

return.

Maybe the IAAF hopes for a more clear evidence of technological

advantage in the next case, or a better consensus among scientists by

that time.

Hugh Herr stated: " People have always thought the human body is the

ideal. It's not. " I agree. High Herr testified on behalf of

Pistorius but it sounds like he may eventually present the opposite

viewpoint.

I fully expect that it will only be a matter of time before users of

prosthetic feet will no longer be allowed to compete with able-bodied

runners, just like wheelchair users.

> The " scientific " evaluation seems to me nothing more than the

> philosophical opinions of two camps: the Bruggemann-led

> purists (who I side with, but not for the scientific reasons

> they put forward) versus the Herr-led prosthetists. I really

> cannot see how this arguement can be settled by scientific

> data - although like many of you I am immensely excited by the

debate!

I side with the purists also, but like for theoretical reasons

and not because of any data I have seen.

Unlike however, I think we will eventually see convincing data.

If we, as biomechanists, can't study this and agree on a conclusion,

our

field of science does not make a good impression. We are all at risk

of

not being taken seriously. Will the public now start questioning the

validity of gait analysis methodology? Will they question our ability

to contribute to the development of prostheses and quantify how good

they are? Yes, I know that sprinting is much harder to analyze than

gait, but this distinction may be lost on the general public (and some

grant reviewers, perhaps).

It is technically challenging, but let's rise to the challenge. Here

is

a real world problem that actually matters, not an academic problem

where different opinions can happily co-exist.

A good scientific discussion is hardly possible at this time, because

none of the data have been published yet. If after publication and

discussion, there is still no consensus, we should at least agree on

how

the next study should be done and how the hypothesis should be tested.

I have asked Rodger Kram if he can post anything to Biomch-L, but no

answer yet. I suspect that both research teams prefer not to discuss

prior to publication.

--

Carruthers

Wakefield, UK

[Guest guest]

In a message dated 5/19/2008 1:15:22 PM Central Daylight Time,

boogatc02@... writes:

There will never be fatigue in the prostheses, which, all else being equal,

gives him an advantage.

***

Perhaps these researchers were going back to some foundational principles

involving limb mass and metabolic cost. Weighing and reduced gravity research

that goes back to 1980 supported the conclusion that the metabolic importance

of swinging limbs is small. If the kinetic energy required to swing limbs was

responsible for a significant portion of the metabolic energy expended, then

by unloading a person (or animal) by a percentage of body weight, (like a

light prosthetic instead of a human foot), this should alter the cost by some

lesser factor. However, it doesn't. At least this is the conclusion that

Dick reached back in the 70's. In testing animals of the same weight

but different distributions of that weight between the limbs and the torso

(like goats, cheetahs, and gazelles), one would expect to find that the

energetic cost would be different. A more massive leg should increase

metabolic

cost, but it doesn't. The cost is identical. found this to be true

despite vast differences in the amount of work necessary for a gazelle to swing

its slighter limbs compared to a cheetah, who has much sturdier limbs. If the

work of swinging the limb demanded metabolic energy, we would expect that the

cheetah would incur a higher metabolic cost. Again, this is not the case.

Ken Jakalski

Lisle High School

Lisle, IL USA

[Guest guest]

> A more massive leg should increase metabolic

> cost, but it doesn't. The cost is identical. found this to be true

> despite vast differences in the amount of work necessary for a gazelle to

> swing

> its slighter limbs compared to a cheetah, who has much sturdier limbs. If

> the

> work of swinging the limb demanded metabolic energy, we would expect that

> the

> cheetah would incur a higher metabolic cost. Again, this is not the case.

>

>

There can be no doubt about: " vast differences in the amount of work

necessary for a gazelle to swing its slighter limbs compared to a cheetah, who

has

much sturdier limbs. "

So if the energy, that also must be vastly different to accomplish these

differing amounts of work, does not arise from metabolism during the run; pray

tell from whence it comes?

Is it merely recycled through the " stretch-reflex " system between strides

once it has been generated during acceleration in the sprint up to speed; if

so, then are the gazelle's and the cheetah's systems equally efficient at

potential energy storage and return as kinetic? Are man's systems equivalently

efficient? If the the answers are " yes! " ; how is it that highly elastic

prothesis material isn't better than nature at conserving energy through the

cycle?

Or is there some (coincidently) equally offsetting inefficiency in the

utilization of the prothesis?

Still very curious,

Boardman

Chicago, USA

[Guest guest]

In a message dated 5/20/2008 1:57:29 PM Central Daylight Time,

A206@... writes:

how is it that highly elastic

prothesis material isn't better than nature at conserving energy through the

cycle?

Or is there some (coincidently) equally offsetting inefficiency in the

utilization of the prothesis?

***

The point in presenting the Dick research was to suggest that the

metabolic importance of swinging limbs is small, and that is in response to the

those who felt the lighter weight of the Cheetah--relative to the return of

the swinging limb--might be what is conferring an advantage for Pistorius.

Again, this is only conjecture until we see what tests the research team

actually performed.

Regarding the elasticity of the Cheetah providing an advantage in the return

of the free swinging limb, that would mean that limb repositioning would

have to be a key factor in determining how athletes achieve faster speeds, and

that is not true for able-bodied runners (JAP 2000) If you are suggesting

that the Cheetah is imparting greater elastic recoil via greater ground support

forces, I should think that the team would have looked very closely at

Pistorius's contact time at top speed.

Again, fun to discuss, but until we see the specifics of their testing

(which may be sooner than later) we really don't know why seven top locomotion

guys signed off on the report.

Ken Jakalski

Lisle HS

Lisle, IL USA

[Guest guest]

> the elasticity of the Cheetah providing an advantage in the return

> of the free swinging limb,

**

No, that's not what I suggested; not at all.

>>If you are suggesting

that the Cheetah is imparting greater elastic recoil via greater ground

support

forces, I should think that the team would have looked very closely at<<

**

Not exactly, but close to what I am asking about. Not " greater ground

support " in absolute terms but in efficiency of return relative to original

input.

And, yes, I would have thought that the team would look very closely at

that and not focus on metabolic cost of swinging the legs; especially since

maintaining ground force production is the concept that goes to the heart of the

Weyand hypothesis for running mechanics conducive to higher velocities (as it

has been explained to me and I understand it.)

This " report " (as yet unpublished) seems to be contrary to the very basis of

the Weyand hypothesis unless there are mitigating circumstances specific to

the prosthesis.

Best regards,

Boardman

Chicago, USA

[Guest guest]

Below is a summary of replies from the Biomch-L:

Dear all,

As a member of the team conducting the first biomechanical tests

with

Pistorius in Cologne last November, I am posting this in

behalf

of our group.

With large interest we followed the conversation in this community

before and after our tests. The discussion about possible test

regimes last summer helped us a lot to design our protocol after the

IAAF asked us to analyse Pistorius' sprinting mechanics in the

phase of maximal sprinting velocity.

Due to reasons of confidentiality we decided not to participate in

the online discussion. We felt it was not appropriate to publish

data

before a final decision was made (data, which has been made

accessible for public was neither published by us nor was the

publication authorized by our institute). We are very pleased to see

the large interest in the community. A short version of the study is

submitted for publication in the Journal of Sports Technology. We

are

currently working on the reviewer comments. The article will

probably

be published this summer. We are planning to publish a more

elaborate

article later.

Thank you very much for participating in this discussion and for

sharing thoughts and ideas!

Wolfgang Potthast

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

We, the scientific group that has refuted the claims of the IAAF,

believe that it is relevant to make the following points based on

recent commentary from the Biomch-L list regarding the CAS's ruling

to overturn the IAAF's decision that banned Pistorius from

international able-bodied competition:

1. The work conducted by our group was done pro bono. None of us

received compensation for our research or participation in the

hearing. The legal team selected our group from many other willing

scientists. All of us were screened and cleared for any potential

conflicts of interest by the lawyers. In addition, Rodger Kram and

Hugh Herr were judged to not have any conflict of interest by the

CAS

court.

2. Our group of scientists was asked to evaluate the scientific

claims made by the IAAF that resulted in the banning of

Pistorius.

3. We evaluated the claims by using data from the literature, as

well

as our own data collected at Rice University.

4. As Ton has stated, this ruling applies only to and to the

Cheetah prosthetics, thus any new prosthetic running technology will

have to be re-evaluated before being allowed in IAAF competition.

5. We plan to publish the data that we have collected in a peer-

reviewed journal as soon as possible.

6. We hope that the interest in the Pistorius case will result

in a number of further studies into questions regarding the

biomechanical and energetic effects of prosthetics on human walking

and running.

Our group includes Drs. Hugh Herr, Weyand, Rodger Kram,

Bundle, Craig McGowan, and Alena Grabowski.

Alena Grabowski, PhD

Postdoctoral Associate

_____________________________________

Dr. Wolfgang Potthast

German Sport University Cologne

Institute of Biomechanics and Orthopaedics

This is an very interesting discussion. I am also eager to see the

data

used as the evidence to support Pistorius. What we need to

demonstrate in this case is whether Pistorius has advantages

over

himself with an able-body, instead of whether he has advantages over

other able-bodied athletes. Could we scientifically demonstrate that

for sure now? If we could not, then I just don't think he should be

allowed to compete with able-bodied athletes.

Bing Yu, PhD

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

Dear All,

Following up on the thoughts of Dr. Willems and others, the

prosthetic

limbs that Pistorius puts to successful use are purpose-built.

They are wonderfully effective at running, but may not fair so well

at

dancing, jumping, skipping, stair climbing, driving an automobile,

pushing a stroller, taking an autumn stroll through the falling

leaves, fishing in a stream, shoveling snow, etc. As humanists we

all

marvel at 's strengths, of character, and of athleticism. As

biomechanists, we may also marvel at the ability to optimize

sophisticated materials for a single-purpose. But as biomechanists,

we

must acknowledge, how far away we really are from duplicating the

marvels of function of the human body. Most athletes train to excel

at

a relatively finite number of events... just like Mr. Pistorius.

However, those that are able-bodied, routinely retain the ability to

accomplish activities of daily living. Perhaps the concept of

defining

success in building a " replacement of an original part of the body

which is absent " is the biomechanical question.

Thanks,

A. Ball PhD

Assistant Professor

University of Hartford

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

I agree with and Ton that the issues here are not

biomechanical. They

are about what constitutes fair competition and hence the issues are

about

the ethics of sport.

Can I remind readers of the e-mail sent to the list last year

http://flyingjumper.com/homeflash.html. Here are a pair of devices

that are

not all that dissimilar from modern energy returning prostheses but

designed

to be worn by an able bodied person. How would the IAAF react to an

able

bodied athlete turning up for competition wearing these? From the

video

there is a distinct suggestion that high jump records might be at

stake (or

maybe not if you subtract the height of the device from the height of

the

jump).

To my mind if you want to introduce aids whether they be prostheses or

wheelchairs into sport you have a different competition (not

necessarily

superior or inferior, just different). The simplest example of this

is that

if you allow a crutch during a high jump competition then you will

end up

with the pole vault.

Which brings us back to the new Speedo swimwear - should all athletes

be

required to perform naked?

Baker PhD CEng CSci

Director Gait CCRE/Gait Analysis Service manager

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

Carruthers

Wakefield, UK

[Guest guest]

I would have thought that the team would look very closely at

that and not focus on metabolic cost of swinging the legs

Hi !

I don't know if Dr. Herr's research team ever pursued the metabolic cost of

swinging limbs. This was simply my conjecture based upon the initial reports

relative to the Cologne study that focused on the weight of the Cheetahs

yielding a reduced metabolic cost. If this was indeed the path the Cologne group

was following, that would surprise me because it would indeed be counter to the

swing data from JAP 2000. Maybe this is just an example of the Cologne position

being misinterpreted.

Ken Jakalski

Lisle HS

Lisle, IL USA

[Guest guest]

Ton van den Bogert wrote on the Biomch-L:

The full decision of the Court of Arbitration for Sport (CAS) can be

found here:

http://www.tas-cas.org/recent-decision (click on Pistorius v. IAAF)

It is interesting to read, and I found it encouraging that the

scientific experts of both parties were largely in agreement. The

conclusion was that no evidence exists for an overall advantage due to

the prosthesis. Key words are " no evidence " and " overall " . There may

be some advantages but also some disadvantages which cancel out in the

overall performance. There may be even an overall advantage (or

disadvantage) but so far the data are not conclusive.

---------------

Carruthers

Wakefield, UK

[Guest guest]

I agree and this is what I've been saying all along. Though the

prosthetics may be advantageous in certain respects, it's unlikely

that he has a net advantage. He should be allowed to run.

Gates

Gig Harbor, WA

>

> Ton van den Bogert wrote on the Biomch-L:

>

> The full decision of the Court of Arbitration for Sport (CAS) can

be

> found here:

>

> http://www.tas-cas.org/recent-decision (click on Pistorius v. IAAF)

>

> It is interesting to read, and I found it encouraging that the

> scientific experts of both parties were largely in agreement. The

> conclusion was that no evidence exists for an overall advantage

due to

> the prosthesis. Key words are " no evidence " and " overall " . There

may

> be some advantages but also some disadvantages which cancel out in

the

> overall performance. There may be even an overall advantage (or

> disadvantage) but so far the data are not conclusive.

>

> ---------------