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Tuesday, August 30, 2011

Bolt's false start and Blake's 'twitch' - the actual start block data explained

The official start data from the 100m final - Blake's twitch doesn't register

This is a final post on the Bolt false start controversy, since as you'll all know, there was some talk that Yohan Blake in Lane 6 (immediately to Bolt's right) might have "twitched" while in the "set" position, and that perhaps he should have received the false start, that he "pushed" Bolt into the false start.

So yesterday, I posted on this question about whether Blake's twitch might have constituted a false start, and wrote the following:
  • If you believe that Bolt was 'triggered' to jump by Blake's movement, then Bolt should NOT have been disqualified, but Blake should have been
  • If you believe that Bolt was unaffected by that movement, then BOTH should have been disqualified
  • And if you believe that Blake's movement was too small and not "irregular", then Bolt is the only athlete who should have been disqualified
So today, I can provide you with the actual data from the starting equipment during the race, courtesy a reader and journalist in Daegu (Thank you so much Remo!).

The image from Lanes 4, 5 and 6 is shown below, for clarity.  You'll recall that Walter Dix is the athlete in Lane 4, while Bolt is in 5 and Blake in 6.  The image should be fairly self-explanatory, but I've explained it briefly below (click to enlarge)

So the vertical grey lines show the firing of the gun, and the green lines immediately to the right of them are the 100ms limit for a false start.  The vertical red line is the point where the actual start of each athlete is registered.  As I wrote yesterday, a start that happens BEFORE this cut-off line shown in green is deemed a false start.

So, each of the sensors in the start blocks is sensitive to the pressure being applied by the athlete.  At some point, as the pressure increases as the athlete pushes off, and the blocks will register enough pressure to signal a start.  I have shown that as a start pressure threshold with the red arrows for all three athletes.  You'll see, for example, that Walter Dix in Lane 4 reaches the threshold soon after the green line, and the start is triggered 139 ms after the firing of the gun (grey line).  

Now look at Blake's graph, in Lane 6.  You'll see a small bump there BEFORE the gun, which I have circled in blue.  This is the twitch that was picked up in the slow motion replays, and which you can see in the video to my previous post on this subject.

If you look over to the right hand side in Blake's pressure graph, you'll see that when he did eventually start (153 ms after the gun), the pressure it took was slightly higher than the pressure registered during his twitch.  I have drawn a dashed green line across from the pressure threshold, and you can see that while the twitch came close to the required level, it was NOT sufficient to trigger the sensors.  Had that twitch been any larger, then Blake would have exceeded the limit, and it would have constituted either a false or faulty start.

This says to me that it would be a pretty tough call to say that Yohan Blake is guilty of a false start, given that the sensitive equipment could not detect it.  It would have been up to the recallers watching the athletes, and it was really a very small movement, only detected later in HD slow motion replays.  Of course, technically, he twitched, and that is, by definition, grounds for at least an aborted start.  But the data say the twitch was tiny, and let's be honest - if Blake was DQd for that, he might have been justifiably upset with the call himself!  So I would conclude that in the end, the right decision was made, even if the technically correct conclusion is that this twitch should have been picked up.  So I'll go with option three in that list above!

Just to add one last though - you can see Bolt's start on the graph above - it comes 104 ms BEFORE the gun even goes off (so it's 204ms before the legal limit), but then you didn't need data to tell you that!  What this graph doesn't say is whether it was Blake's twitch (however small) that caused Bolt to jump, or whether Bolt would have gone anyway.  That remains a point of discussion I guess.  Regardless, it's all just conjecture now, the race is in the books!  


P.S.  Let me take this chance to also correct an error in the post I did earlier today - I said that the bronze medal in the men's 400m was won by Jonathan Borlee.  It was in fact KEVIN Borlee who claimed third, while Jonathan was fifth!  The danger of identical twins!

Enjoy the rest day tomorrow!

IAAF World Champs - Rudisha delivers and Kirani James "arrives"

IAAF World Champs: Rudisha, James and Zaripova get gold

Day 3 of the IAAF World Championships brought more success for Kenya, in the form of David Rudisha's anticipated gold in the men's 800m.  It was their third gold of these championships, but may be tempered slightly by the result of the Women's steeple where they would have been hoping for another gold, but left instead with one bronze courtesy Milcah Cheywa, who was denied by Yuliya Zaripova of Russia.  Russia had a great day with two golds - Zaripova's and Chernova's in the heptathlon, where she denied Jessica Ennis a much anticipated gold medal.

Other golds on the day went to Germany (men's discus), Brazil (women's pole vault) and Grenada, with perhaps the race of the day coming in the men's 400m, where Kirani James, the exceptional 19 year old (or he will be on Thursday) beat LaShawn Merrit in a great final 100m to claim gold.  Having been identified as one for the future, James ushered the future in immediately by delivering on his promise, and setting up a great rivalry with Merritt ahead of London next year.

Short event summaries below.

Men's 800m - Rudisha delivers

The 800m event has traditionally been regarded as one of the most open and unpredictable in the World Championships.  As recently as 2009, there were probably a dozen men all capable of winning gold and if you ran the final five different times, there was a chance that you'd get five different winners!

That was then, this is now - David Rudisha, so disappointed to fail in 2009 when much was expected of him, has since matured into a world record holder and dominant world beater.  As a result,when he stands on the start line in any race on the global circuit, the thinking is usually how fast will he run, and competitively speaking, by what margin will he win?

The World Champs are a little different - the lack of pace-makers means that the race has to be won either tactically (which can see normally unheralded runners emerge in frantic final 200m sprints - watch the 1500m races to see this happen!), or it must be run from the front.  So the question ahead of today's 800m final was not only whether Rudisha would come through the test (most expected it), but how would he run in order to avoid the numerous tactical pitfalls of the event?

Those who "guaranteed" victory on the basis of Rudisha's superior times alone perhaps overlook the difficulty of running sub-1:43 as a solo effort from the front, and even with Rudisha's dominance in terms of his PB compared to other athlete's, the field is competitive enough that a race finishing in 1:43 would be close until at least the final 50m - tension or tightness would be punished.   So this was going to be an "anxious" race for the world record holder.  The general expectation was that he'd avoid the bunching and boxing of a slow race and lead from the front.

In the end, that's exactly what he did, and he ran the 800m final a lot like a middle distance race.  That is, he started fast (23.81s for the first 200m), got into the lead, then controlled the pace in the middle of the race (27.52s and 26.66s for the next two quarters) and then picked it up again with 25.92s over the final 200m (see figure right) to win gold going away from the chasing field.  This kind of pattern is what you usually see in 1500m and mile races, and that he did it so strongly in an 800m race (under pressure from behind) is testament to Rudisha's quality, and his obvious capacity to run faster when needed.

It was enough for a gun-to-tape victory, in a controlled manner that is possible only when you are completely in command of the event and the competition.  The time of 1:43.91 was made to look comfortable, and the way the race was constructed suggested that it was.  In second, a late charge by Abubaker Kaki (1:44.41) made good on the expectation that he would be Rudisha's biggest challenger, though in truth, he was never truly challenging.  Yuriy Borzakovskiy claimed bronze for Russia.

Rudisha delivered on the expectation and if he stays healthy, it's difficult to see an 800m gold medal going anywhere other than Kenya for the next few World Championship cycles.  The once-unpredictable event has become "routine" (but not quite a forgone conclusion), and that's a measure of the quality of David Rudisha.

Women's 3000m steeplechase - front-running championship record to Zaripova

Speaking of dominant front-running performances, gold in the women's steeplechase went to Yuliya Zaripova of Russia, in another gun to tape victory.  She hit the first hurdle in the lead and never surrendered it, reeling off a 3:00, then 3:04 and a final kilometer in 3:03 for a world-leading time and personal best.  In doing so, she went one better than in 2009, where she had been outkicked by Marta Dominguez of Spain (as Yuliya Zarudneva back then).

The challenge came initially from Kenya, but one by one they dropped off, and it would be Tunisia's  Habiba Ghribi who claimed silver with a strong final 800m.  The dominant athlete of the year so far, Milcah Cheywa on Kenya, who has basically wrapped up the Diamond League title for the event, would come third to claim consecutive bronze medals in World Championships.

It was, in one sense, a surprise, because Cheywa has dominated in 2011, going unbeaten until today.  In  another sense, perhaps it was not.  The Kenyans, for all their depth and complete dominance in the men's steeple, haven't quite managed to dominate the women's discipline.  Yet.  Rather, Russia have been the championship performers, and currently hold the championship record from 2007, the Olympic gold, and the world record (in the Beijing Olympics).  The steeple is clearly an event they have identified as a gold medal prospect.

Having watched Kenya's women in the 10,000m, and knowing the caliber of athlete they have over 5,000m, I suspect that it is only a matter of time before the same is true in the steeple.  For now, the event is perhaps more "open" as a result of its relative newness in athletics, and I expect that to change soon, once athletes of the caliber of Vivian Cheruiyot, Linet Masai and Sally Kipyego start to run in it as well. Once athletes with 14:30 5,000 caliber begin to turn to the steeple, I'd expect the performances to leap ten seconds forward and sub-9 clockings will become common.  Cheywa then, is the first great steepler from Kenya, but those who follow, I expect will surpass that level.  It will be interesting to see if the rest of the world "follows" or whether we see the same situation to develop as for men's steeplechase.

But right now, Russia lead the way, and Zaripova leads the world.

Men's 400m - Kirani James delivers on his promise in the race of the day

Kirani James of Grenada became a name to watch when he ran a world-leader a few weeks before the World Champs.  His talent was undisputed, and only two days short of his 19th birthday, everyone was saying that no matter what happened in Daegu, he was a name to watch in the future.  Well, that wasn't enough for Kirani James - he was ready for success now.  And so he won the gold in the 400m in a time of 44.60s, with a late charge to catch and pass LaShawn Merritt (44.63s, only 0.03s behind).  It was a race reminiscent of the great finish between Amantle Montsho and Allyson Felix yesterday, but with one difference - this time, the charging athlete did overhaul the leader to win.

For Merritt, it would have been a disappointment in the sense that he was 10m from defending his title, but he may be satisfied nonetheless.  A 21-month ban for a drug infringement (Extenze - improve your manhood) meant he was in Daegu as a wildcard, his drug ban ending so recently that he didn't even have the opportunity to race in the USA trials.  He leaves Daegu knowing there's work to do, but in possession of silver and the world lead from his first round heat.  Third went to Kevin Borlee of Belgium, one half of the identical Borlee twins, in 44.90s (Note - the initial post said Jonathan - my apologies! That's the trouble with identical twins! My mistake!)

James has a combination of power and relaxation, and today he came under pressure from Merritt with 180m to go.  Despite looking a little more ragged than he has in previous races, he responded without losing his form, and becomes the third youngest world champion in history (Ismael Kirui and Eliud Kipchoge were younger).  If he continues to improve, he's the man to beat for a long time to come.  At the very least, his rivalry with Merritt over the next few weeks and into London will mean the 400m is an event to watch.

Other events

In other events, Robert Harting won the men's discus.  The only reason I mention this is that in Berlin, this provided one of the highlights of the Championships, because Harting's celebrations involved picking up Berlino and spinning him around.  Berlino, the greatest mascot ever seen in athletics (and who should have been imported to Daegu for a week).  Ok, that was a little tongue in cheek, but Berlino was a highlight and added a bit to the entertainment value of the Berlin Champs.  There's a video at the bottom of this post.

Jessica Ennis did NOT win the heptathlon, which was a bit of a surprise. It had gone mostly to plan for the British athletics icon until the javelin, when a large underperformance saw Russia's Tatyana Chernova leap ahead and then defend her points lead in the 800m to claim gold.  Sebastian Coe was the invited dignitary for the medal ceremony, and he was no doubt expecting to hand gold to Ennis, who is one of Great Britain's stars in the build-up to the London 2012 Olympics.  A disappointment for Ennis then, and one wonders whether this increases or decreases the pressure on her.  She'll take heart knowing that it was really just one very weak event that cost her the points, and she has the opportunity to bounce back in a home Olympics.  It certainly adds intrigue to the event for London, and perhaps reduces the pressure on Ennis (though not by much).

The women's pole vault was won by Fabiana Murer of Brazil, with a 4.85m clearance for a South American record.  Silver and bronze went to Martina Strutz of Germany (4.80m, a national record) and Sveltana Feofanova of Russia, respectively.  Completely out of the medals was Yelena Isinbayeva in sixth.  Her comeback hasn't gone quite according to plan, though London will surely be the goal.  This result, as it has done in many events, perhaps asks more questions than it answers ahead of the Olympics.

Tomorrow is a rest day (bizarrely - I don't recall a rest day in an IAAF Championships before, so beats me why).  It sees the 20km walk. The next big track action comes on Thursday, and I can't understand why this rest day has been introduced.  If anyone knows, please let us know in the comments!


And lastly, here is Berlino.  The Daegu mascot is trying, but these are big shoes to fill!  Enjoy the athletics on Thursday!

Monday, August 29, 2011

The Blake-Bolt false start dispute

Did Blake flinch, and was Bolt unfairly disqualified?

So it may be a new day, but perhaps not surprisingly, the debate about the men's 100m final has continued. But with one unexpected twist.  Rather than talking about the "what if Bolt had not false started?", this morning I woke to the question of "Should Blake, and not Bolt, have been given the false start?".

The question was raised on Letsrun.com, but came via all-athletics.com, and basically, it has been noticed in slow-motion replays that Yohan Blake, who starts in Lane 6 to the immediate right of Usain Bolt, twitches very slightly in the "get set" position.  Below is a video, which is courtesy of Letsrun.com, showing the start.  The moment in question is at around 13 seconds, so you may need to play it back and forth a few times

You'll see Blake's left leg move on the block, and then Bolt jumps out.  It was very clearly a false start by Bolt, make no mistake.  The question is whether the twitch by Blake, that tiny movement, should have constituted a false start or not?  And if "yes", then should he have been disqualified along with Bolt, or were they two independent events?

It's important to explain the rules on this one. In terms of the starting, the rules say the following:
  1. From Rule 162.5. "On the command 'On your marks' or 'Set,' as the case may be, all athletes shall at once and without delay assume their full and final set position."
  2. From Rule 162.5. "After the command 'On your marks' or 'Set,' if an athlete disturbs other athletes in the race through sound or otherwise, the Starter shall abort the start."
  3. From Rule 162.8. "The Starter should warn or disqualify only such athlete or athletes who, in his opinion, were responsible for the false start."
Technically speaking, there is an aspect of each of the above rules that was contravened by Blake with that tiny movement.  Realistically, however, it's a little more tricky than this.

If you read the IAAF Starting Guidelines (kindly sent by JC, thanks!), you'll see point 5.2 say that following:
There is no perfect holding time in the set position. In reality, there must be a discernible hold to ensure all athletes are steady and in the correct starting position. The Starter must stop a race if:
  • An athlete, after assuming a full and final set position, commences his start before receiving the report of the gun (Rule 162.6).  
  • He receives a signal from the false start equipment. 
  • Any Recaller observes an irregularity with a start. 
In addition, not all movements in the “set” position are to be regarded as “commencing the start” and thereby potentially leading to a false start. Such instances should be dealt with either by standing the field up or in serious cases, invoking the disciplinary provisions.
So a couple of things about this clause:

First, the starter and a pair of Recallers are present to watch athletes and make what is basically a judgment call about any irregularities, such as those small movements.  They also have electronic timing equipment, in the form of pressure sensors in the blocks that pick up any movements prior to the gun.  In theory, if an athlete is found to have started (that is, applied pressure to blocks) while in the "set" position, or sooner than 0.100 s after the gun, it is deemed a false start because it is theoretically not possible to REACT this quickly. The equipment, combined with visual judgment, is supposed to detect unusual premature movement.

Importantly, note that it is not necessarily the case that all movements are deemed to lead to a false start - some instances can lead to an aborted start where the field stands up, and if serious, they can lead to disqualification, but it's not necessarily a given that it will be disqualification.

So, returning to the Blake/Bolt incident, that movement, as clear as it was in super slow-motion replays and HD, may not have been deemed sufficient to be called "irregular".  I suspect that such small movements are quite common, though the Blake movement is clear on the replay.  It's a judgment call as to whether it should have constituted, at best, an aborted start where the field stands up.  At worst, it was a false start of its own.  What we can almost certainly surmise that it didn't produce enough of a pressure change on the block to register on the equipment, and it clearly wasn't seen by the officials at the time.  The rest is likely subjective judgment, hence the controversy.

Next: Does this mean Bolt should NOT have been disqualified?

The next thing is that IF you assume that Blake did twitch, is it true that Bolt should not have been disqualified, or were the two false starts independent events?  This is important because again, if you read the rules, you see the following:
In theory, a Starter can award a false start to several athletes if it is indicated that their movement was more or less simultaneous. Otherwise, the false start must go to the athlete indicated as making the first movement (Point 5.3)  
In other words, if there are two false starts, then there is a call to be made about whether they are independent, or whether one influenced the other.  You may recall the case of Sally Pearson and Laura Turner in the Delhi Commonwealth Games last year - here, these two athletes false started 0.001 seconds apart.  Turner was first, and so she was disqualified, but raced under protest.  Pearson was initially not disqualified, but was later DQd on appeal, because it's clear that her false start was independent of Turner's - there's no way you react and produce a start 1/1000th of a second after the "instigator".  So in this case, both athletes were rightly disqualified for what are independent or simultaneous false starts.

So, back to Bolt and Blake...

  • If you believe that Bolt was 'triggered' to jump by Blake's movement, then Bolt should NOT have been disqualified, but Blake should have been.  
  • If you believe that Bolt was unaffected by that movement, then BOTH should have been disqualified.  
  • And if you believe that Blake's movement was too small and not "irregular", then Bolt is the only athlete who should have been disqualified.

A range of scenarios, and ultimately, it comes down to a mix of technicality, but needs a judgment call.  The way I see it, Blake's movement was small and slight enough that it wasn't seen by the recallers and wasn't detected by the equipment.  Therefore, I'd say an aborted start, not a false start is the fairest sanction.  After the fact, that helps nothing, of course.  As for Bolt reacting, he himself hasn't mentioned it, but the argument is that it may be sub-conscious.  In theory, they are close enough that it is possible.  But ultimately, seems a judgment call.  What would yours be?


Sunday, August 28, 2011

Day 2: False starts and flying finishes

False starts and flying finishes: Day 2 drama in Daegu

So if Day 1 produced dominance for Kenya, Day 2 produced drama.  It was, in the day's two track finals, a day full of drama.  It began with an incredible final lap sprint in the men's 10,000m final, and ended with the disqualification of Usain Bolt.

It was that disqualification that will hog the headlines tomorrow, and therein lies the first problem.  Bolt false started, there's no question.  His false start was so big that I would estimate that half the stadium realized it before the replay and before the official decision.  The air was let out of the stadium more dramatically than I can recall and the final went on to become one of the bigger anti-climaxes I can recall.  And that is in sport, let alone athletics.

And so spare a thought for Yohan Blake, who went on to win the title (at least keeping the medal and bragging rights in Jamaica) in 9.92s.  But the reality is that the media coverage will be split, and heavily in favour of Bolt's DQ.  And the thing is, there's no absolute guarantee that Bolt would have won the race anyway.  He was a massive favorite, yes, and he looked good in the heats and in his semi, but Blake also looked very strong and the 9.93s was into a 1.4m/s headwind.  That's probably worth a low 9.80s and that would certainly have extended Bolt.  I still would have made him an overwhelming favoirte, but at best, we were denied a really intriguing race, and Blake will be denied the coverage he perhaps deserves.  But, having said that, I can also appreciate where the focus will be placed!

The false start rule under the microscope

This zero-tolerance false start rule falls under the microscope (again) as a result.  Today we had some great posts on Twitter, and so I'd guess people are split roughly 50-50 on the issue.  Here's an article calling the rule either "cruel" or "inhumane", for example.

You may recall an era where every single athlete was given a warning.  The result was that you could have up to nine false starts in a race before you saw a disqualification.  For a few reasons, that rule was scrapped.  First, it means that races sometimes took 15 minutes to get underway!  Secondly, it enabled athletes to manipulate the race by deliberately false starting.

So it was a step forward in terms of time-management when the rule was changed to one false start for the field.  That happened in 2003, and meant that the first false start placed the entire field on a warning, the second would see an athlete disqualified.  That didn't deal with the gamesmanship aspect, and it probably didn't create a fair scenario because one athlete would get away with a jump, others would not.  If memory serves me, this happened to Bolt in Berlin in 2009, and as you'll know, he went on to run 9.58s as a result of the reprieve it provided.

Today, no such luck. The rule was changed in 2010, and suddenly, everyone was on a final warning, from the outset. Bolt made a massive false start - there was no controversy at least - and so he was gone.  The rule has been controversial, and it's not just today's race that has made it so.  There has been a growing sense that this kind of thing would happen soon, and may have a negative impact on the sport.  And Tyson Gay had raised his objections to it back in 2010 and he made a very pertinent points.  I think the key one is pointing out the inconsistencies between starters. He is quoted in the interview as saying:
"They need some sort of automatic sensor or automatic gun so that it goes off the same time every time. We have different blocks, we have different people holding the gun, it's ridiculous"

I can see how that would be an issue, though I can also see some of you reading this saying that's part of the sport, and the elite have to deal with it.  I think that given the severity of the punishment, a more 'secure' method at the start would be beneficial and even necessary, so I would agree with Gay.  I've seen some starters hold guys for an eternity, others not (though having said this, this is not what happened to Bolt).

Stepping back a little, there are a number of things to consider.  Swimming has a one false start rule, and it has been successful (that is, relatively uncontroversial) there.  I can't think of a big DQ in the last four or five major championships.  If I'm missing one, let me know.  However, I'd be cautious about making the direct comparison between the sports and saying that if it works there, it should work in athletics.  There are a few differences between the starts, and even the stadiums where the athletes race.  The starting position in running (in my personal opinion) places more of a premium on the start because it's a less steady position and you have a three-phase start (on your marks, get set, and bang) compared to two phases for swimming.

I can't think of any other sports that punish athletes as severely for making "errors" that are actually part of the purpose of the sport.  By that, I mean that in track, the entire objective is to get out of the blocks fast and get to the finish line as fast as possible.  The purpose thus encourages athletes to be at the limit for speed.  To me, the analogy is that in football (soccer, I mean), players have to win the ball, and are thus compelled to tackle.  Sometimes they mistime challenges.  We don't condone the mistake, but unless it's deliberate or very dangerous, they receive yellow cards - a warning, which is followed by dismissal for repeat offence.  Of course, the difference is that soccer unfolds over 90 minutes, come what may, whereas in track, the race would never start if every guy got a warning first!  As we can remember all too well...!  So I appreciate the implications of warnings.

But the downside of the rule was made clear today - the biggest name in the sport, its icon and probably one of the five most recognizable sportspeople in any sport was eliminated from the marquee event of his sport.  Again, the counter-point to this is that if we were on the warning rule, and say Kim Collins had jumped the gun, Bolt could well have done it second, and he'd also be DQ'd for his first offence - same situation as today, except it would have taken two minutes longer to happen!  So these scenarios can go any way you want them to, and so the more I think about it, the more I realise there's really no "right" way to do it!

For the IAAF, it's a sticky one because let's face it, athletics needs Bolt, and it needs to be able to leverage his success to expand the sport.  Athletics is a commodity, and so it competes with other sports, and other forms of entertainment, and so there's a big regret when something like a DQ happens on the biggest stage of all.

Think for a second of "moderate athletics fans", those who really only watch the massive events, and the massive athletes.  There is no more massive combination than Bolt in a World Championship 100m.  What are these moderates thinking tonight?  That they were denied a chance to see the greatest because of a rule they don't fully understand?  Are these people more or less likely to switch on to watch next week, when the Diamond League race is on in Zurich?  Not that this argues for a rule change, but it does hopefully make you realize the complexity of the problem.  This is not as simple as saying "rules are rules" or that the rule MUST be changed.

Also, I am not that I'm saying that certain people must be excused - if there is a rule, then it applies to all.  I just wonder though whether it might be worth accepting that in a race where hundredths of seconds matter, where so much hype and build-up goes into 10 seconds of running, a mistake should not be punished in the way that it currently is. Perhaps a possible sensible compromise comes from this really good piece by the Robert Johnson of Letsrun, where he makes the compelling point that in a major championship, the rule should stand, whereas if it were to happen in a Diamond League race, where organizers pay appearance fees to get athletes so that fans will spend their money specifically to see an athlete compete, it might be worth allowing the athlete to continue to race unofficially.  Let's not deny people "access" as easily as we are, in other words.

I think that may be the best compromise regarding disqualification and certainly for these events.  For the big championships, I'd still like to see a return to the one false start for the whole race rule, but that's my personal feeling.  And I realise it means that the second guy to jump the gun gets the red card, but at least this allows everyone that first "aggressive" attempt at getting away first.  After that, everyone has to sit back in the blocks, be a little more conservative.

But in all this, let's not get carried away and say that it's the IAAF or the rule's fault.  There have been a lot of people, including Bolt's manager saying things like "this false start rule, it's going to screw us all up", but that's kind of like blaming gravity for your death if you jumped off a high building.  It's clearly the fault of the athlete who false starts, not the rule - the issue is whether the fault is worthy of the severity of the sanction, at least the first time.

I don't have an answer, but I'd love to hear your thoughts.  Unfortunately, the result of all this is that from now on, Yohan Blake is world champion, but when people talk about it, most times they'll say "wasn't that the year that..."  A pity, but well done to Blake - he beat everyone.

Men's 10,000m - incredible final lap

OK, so honest answer, who picked Ibrahim Jeilan to win the gold?  Mo Farah was the big favourite for the gold, and the question was, would Kenenisa Bekele show up out of nowhere, for his first race in two years, and win a fifth title?  The answer was no, he actually stopped at about 6km, and the battle was then on between Farah and the Ethiopians (Kenya's men played second fiddle to the women big-time - they finished out of the medals, in contrast to the all conquering women last night, so a bit of a rebound for them!)

I think Tadese did much of the early work.  I say "think" because I have never sat through such dire coverage of a distance race before.  We saw the first two laps, and then cut to crowd shots.  A few long jump attempts were shown, with three replays on each one, and a healthy dose of more stadium and crowd shots between. Then it was about 15 seconds of the 10,000m race (the race was already at 4,000m) before we cut to the middle rounds of the discus final.  Middle rounds, not the medal deciding throws, mind you.  Again, crowd shots to keep us entertained between throws and more replays and eventually, with about 2km to go, we got uninterrupted coverage of the 10,000m.

I believe that in the UK, there was a better feed - count yourselves lucky, because the rest of the world saw probably 25% of the race, that's all.  It was, as one tweeter said, the equivalent of watching the first 5m and last 20m of the 100m final.  When you combine this kind of diabolical directorship with the general, non-athletics fraternity perception of the 100m final and Bolt's DQ, it wasn't a great day for athletics, all in all.  I honestly believe the IAAF should step in and control the broadcast because most athletics enthusiasts feel this way, some very strongly.  If you look at the "package" that is Formula 1, or NFL or basketball, it's slick, polished and adds to the value of the sport.  Athletics is lagging behind in a big way.  If you want to read a great insight into this, read this article, focused on the Women's Marathon, but it could just as well have been written about the shambolic coverage of the men's 10,000m final.

The end was spectacular though, when it came.  As mentioned, Mo Farah has dominated every race this year, and always with the same approach.  His finishing kick had seen off most runners in the race before this one, over 5,000m and 10,000m, and with the pace being relatively slow, it was looking more and more like his kind of race.  I made the error, with 1km to go, of saying that he really should win it from there, with the kick over the last 300m.

Then Farah went earlier than usual.  He hit the front with 600m to go and wound the pace up, the big surge coming in the home straight, approaching the bell.  The penultimate lap was done in about 60 seconds, and Farah charged through the bell, opening up five meters of Merga and Jeilan behind him.  Down the back straight, that lead grew and then held at about 8 to 10m.  It looked typical of Bekele and Gebrselassie, actually, in the days when they kicked early and then held, before kicking again.

But this time, Jeilan clawed it back, very slightly.  Farah covered the 200m from the bell in about 26.4 seconds, but Jeilan hung on.  With 200m to go, he was still in touch (just), edged back around the bend, and with 120m to go, it was clear that Farah would have to kick again to hold him off.  The final straight was a magnificent race, Jeilan having the speed to close it out.  A high 52 second lap compared to Farah's low 53 seconds was enough to give Ethiopia its fifth consecutive gold over 10,000m.

Did Farah go too early?  I don't know.  I do wonder whether a final 300m kick might have been better, but that's hindsight for you!  He certainly went earlier than most might have expected, but that's not the same thing as saying "too early".  He ran the final lap in a shade over 53 seconds, and that's normally good enough.  That he went from 450m doesn't change what Jeilan did, and to hang on, then claw back the deficit was a magnificent run.  I think the best conclusion is that Farah raced well, he did everything he could, but found Jeilan just that little bit faster in the end.  Farah will have another chance over 5,000m and I still wouldn't bet against him.

Jeilan for his part, was an unknown before this.  The Letsrun analysis of the race (which is worth a read) has some information on him - a 27:02 at the age of 17 says he had enormous talent, and he's spent the last few years honing that in Japan, and he's clearly a class act.  It will be interesting to see if he builds on this, and becomes a dominant distance runner like some of his illustrious predecessors.  He certainly entertained in the victory lap, a much more expressive champion, dancing, posturing, and he speaks good english, which I do think is a "value-add" for the media side of the sport.  His is a name most won't be unaware of ever again!

Other events

Speaking of talented 17-year olds from Ethiopia, Mohamed Aman sprung the surprise of the 800m semi-finals, when he beat Abubaker Kaki in heat one.  Kaki in fact finished third and with only the top 2 guaranteed a final spot, the Sudanese had a nervous wait during semi finals 2 and 3.  In the end, he was the fastest "loser", and in fact, his 1:44 time gave him the fourth fastest time, but his semi-final wouldn't have given him too much confidence.  He was super aggressive, running the first 200m in 23.8s, and hitting the bell in 50.19.  He continued to slow after that and with 120m to go, it was clear he was in for a real battle, with the field, some 10 m behind at the bell, now on his shoulder.

In the end, Aman won the race, Marcin Lewandowski was second and Kaki third.  The other semis were won by Nick Symmonds and the incomparable David Rudisha, who seemed to coast to a 1:44.20 in his. It means the "dream final" of Rudisha vs Kaki is on, and happens on Tuesday.  Rudisha is a huge favourite, but the slightest tightness or messed up pacing, and the field will be close enough to pounce.  Rudisha seems capable of a 1:43-low, and I'm not sure others are, so it will probably take a Rudisha "off day" to produce the surprise, but that can happen - this is the 800m after all!

The men's decathlon gold was also awarded tonight - it was solidly defended by Trey Hardee of the USA, but the excitement came in the form of Ashton Eaton, who entered the final event, the 1500m, in third place and needing about four seconds to overhaul Leonel Suarez of Cuba.  He did just that, running aggressively, but storing up for a huge kick on the final lap, that the Cuban was unable to match.  In the end, Eaton got just over 5 seconds, and the silver changed hands in the final 100m of the two-day event. Hardee was solid, helped by a PB in the javelin, but Eaton's "breakthrough" continued and the two should resume their battle with Suarez in London.

In other events, the men's 110m hurdles heads towards what may be the most closely contested race of the championships.  The big three - Robles, Liu Xiang and David Oliver - are all healthy and have PBs within 0.01 seconds of one another.  The race the semi and final tomorrow.  And LaShawn Merrit laid down a great marker for the 400m with a 44.35 in qualifying.  It's the fastest in the world this year, and given the state of men's 400m running, it's wide open enough that this kind of performance, if carried through, makes Merritt the one to watch.  The semis are tomorrow night.

Also tomorrow are the women's 400m and 100m finals.  Will the 400m give Botswana its first gold from Amantle Montsho. or will Allyson Felix take the first step towards a double gold?  It's a super deep race, and can realistically be won from Lanes 1 and 8 as well, but Montsho starts as slight favorite.  And can Carmelita Jeter be beaten by the Jamaicans?  After today's action, don't bet on anything!

Enjoy the morning heats (if you watch them) and the racing tomorrow!


Saturday, August 27, 2011

IAAF World Champs - Kenya's day

Day 1 belongs to Kenya...entirely.  As in all 100%, 6 out of 6

The day 1 medal table at the IAAF World Championships makes for extra-ordinary reading.  There's only one team on it - Kenya.  It a display of unparalleled dominance, Kenya took every single medal on offer.  It helps that the medals were available in the longest distance running events, the marathon and the 10,000m events for women.

But it was dominance like we haven't seen on a given day - first, second and third to kick off the day in the marathon, and then first, second, third and fourth to end it in the 10,000m.

Both races were testament to team dominance, but were punctuated by individual superstars, as first Edna Kiplagat re-inforced her emergence as a marathon star, and then Vivian Cheruiyot underlined her status as an all-time great in the making.  Both where also characterized by a battle between Kenya and Ethiopia.  In the end, it was no contest.  Kenya has always been a distance powerhouse, and in recent years, their women have begun to achieve the dominance we used to see from their men.

Today, they exceeded it, with arguably the most dominant day for any nation in the history of the sport.  Only six medals were on offer, of course, and there have been days where a nation has won more golds or more medals.  But six out of six, 100% success, is the kind of start to the championships that mean that even if they win nothing else (and with Rudisha in the 800, Chemos in the Steeplechase, the men's steeplechase, the men's 1500 and Vivian Cheruiyot in the 5,000 to come, this seems impossible), Kenya have already had a successful 2011.

Women's marathon - the biggest threat to Kenya was a Kenyan heel-clip!

The women's marathon was won by Edna Kiplagat in 2:28.43.  Priscah Jeptoo took second, while Sharon Cherop took bronze.

Cherop also nearly took her team-mate out of the race.  With about 15 minutes left to run, Cherop and Kiplagat cut across one another and they clipped legs.  In truth, it was nobody's fault, but Kiplagat went down fairly hard.  Cherop sportingly waited, and they helped Kiplagat back into a rhythm and she went on to win the day.

It was that kind of day for Kenya - the rest of the world was unable to keep up, and the biggest threat they faced turned out to be from within!  For a more detailed analysis of the race as well as press conference footage (and this will be the source of the best insight you get on all the events in these Championships), check out the Letsrun.com analysis of the marathon.

Women's 10,000m - another sweep, led by Cheruiyot

Then came the women's 10,000m.  This was a race billed as a clash between Vivian Cheruiyot and Mesert Defar, but it never materialized.  It was also expected to produce much drama, as track 10,000m races often do, particularly the 2009 title, where Meseret Defar tied up with 50m to go, then Melkamu looked to have won it and even began celebrating before Linet Masai pipped her for gold.

The drama was absent this time, but there was another "d" - Dominance.  Kenya utterly dominated this race, and would claim the top four places.  After the early pace was set by Shalane Flanagan, the Kenyans took over just before 4,000m in the form of defending champion Linet Masai who just maintained a steady pace of around 3:05/km.  The field was progressively cut down, and eventually, Defar was dropped with 2km to go.

That was a big surprise - her 5km season's best of 14:29 earlier this year would have suggested a better display than she produced, especially given that the first 5km of this final was run in 15:47.  Things must have turned for the worse since that performance, because with 8km to go, she was gapped and she would eventually not even finish the race.

At the front, only Meselech Melkamu resisted, the lone presence among four Kenyans.  Five reached the bell together, and then Cheruiyot went ahead and wound the pace up.  Only Sally Kipyego stayed in contact (not Masai as the commentary said until about 10 min after the race!), and Melkamu was in third, seemingly poised to break the Kenyan sweep.

But with 100m to go, Melkamu was reeled in and passed, first by Masai (who deserved a medal for her efforts - she led for almost the entire final 6,000m) and then by Priscah Cherono.  It meant Kenya went 1, 2, 3 and 4.

The pace in the end wasn't all that spectacular - Cheruiyot ran the final 400m in about 61 seconds, to clock 30:48.98 (second half is 15:01, which is quick).  Cheruiyot picked up a personal best, and her first gold of these championships.  Based on the form of the Ethiopians, few would bet against her winning the 5,000 later in the week.  We've seen faster races, and we've seen faster final laps, but we've rarely seen such complete dominance of a day and two events.

Kenya must be a happy place to be in the village tonight!

Other action - big guns on course, so far

In other action, the men's 800m went more or less to plan.  David Rudisha and Abubaker Kaki both completed comfortable front-running victories in their heats.  Their next stop is the semi-final, where it should be a lot tighter, but they look good bets to reach the anticipated head-to-head in Tuesday's final.

Usain Bolt rocketed out of the blocks in his 100m heat, and then "jogged" to a victory in 10.10s.  With Powell, Rodgers, Gay and Mullings all out (that's the four fastest men by time), Bolt was already the favourite, but as far as "routine" 10.10s performances go, Bolt made his look pretty spectacular.  The semi-final and final are tomorrow night.  Don't bet on a record, but don't bet against Bolt winning either.

Other events to look out for tomorrow are the men's 10,000m final, where there's a chance that the gold will NOT be going to Kenya or Ethiopia.  Mo Farah is a big favourite, but the big danger will be Kenenisa Bekele.  He hasn't raced in more than a year, and so no one really knows what to expect from him.  In one sense, you'd think it foolish to bet against a man who has actually never lost a competitive 10,000m.  But on the other, you'd be foolish to bet on a man who hasn't raced in so long!  Bekele is a big unknown, and that should be a fascinating race!

Follow us on Twitter for quick thoughts and updates

That's it for Day 1.  Please join us for coverage throughout - the action in Korea takes place at a really inconvenient time here in South Africa, as it happens right in the middle of the work day.  I'd wake up early to watch, but missing work might be a bit challenging...on some days, anyway!  So I may miss a few things live, but will try to bring you as much analysis and reporting as possible, even if it is delayed.

The twitter account will be active though, with regular thoughts and updates, and so if you want to stay abreast of the super-condensed Science of Sport analysis, follow us on Twitter!  It's already produced the debate that inspired the last post on Oscar Pistorius' performances!

For the rest, Letsrun.com are in Daegu, and their great post-race analysis and pre-race previews are highly recommended, so keep that page as a favorite for the next week!

Join us tomorrow!

Thursday, August 25, 2011

Pistorius: the "12 sec advantage" and mechanical superiority

Revealing the Pistorius science part 3: "We knew all along", as the debate turns to an argument
"We conclude that the moment in athletic history when engineered limbs outperform biological limbs has already passed"
That was the concluding statement from the first of a series of back-and-forth articles that were published in the Journal of Applied Physiolgy in November 2009.  It was written, remarkably, by two of the scientists who had in fact been involved in the research that was presented to the CAS when they made the decision to legalize Oscar Pistorius' carbon-fiber limbs 18 months earlier.  A research team of seven conducted the testing on Pistorius in Peter Weyand's laboratories in early 2008, and the fact that two of them would come out with a completely different conclusion after the hearing begs many questions - why did the difference in opinion not emerge sooner?  Was that difference deliberately snuffed out and 'hidden'?

Note that neither Weyand nor Bundle were present at the CAS hearing, and that begs a question or two itself.  Why did Weyand not attend the CAS hearing, or at the very least, Bundle, since they were of the differing opinion?  Was pressure applied to ensure that CAS did not hear a word of this possible advantage, and did they rule based on incomplete and 'manipulated' information?

This conclusion is the subject of this final piece in the full review of the Pistorius evidence.

The role of the lawyers, and the scientific integrity of the process

The paper emerged 18 months late, along with a Weyand saying: "From the instant we collected the gait-mechanics data and saw how short his swing times are, we said to the group [of scientists they were working with] that it's really clear he's got an advantage".

So to be clear - the evidence existed, and so did the interpretation that it provided an advantage.  But for whatever reason, this did not emerge until a year and a half later.  The "group" had clearly reached some agreement that this interpretation of an advantage would remain "hidden", because Hugh Herr and Roger Kram went to the CAS and presented a united front, saying that there was no scientific basis for an advantage based on the IAAF testing (if you read the CAS verdict, there is not a single mention of this possible interpretation).  Where were Weyand and Bundle in this process, you may be wondering?

Even if you accept that there are two interpretations of the data, you'd think that this one should at least have presented or discussed.  It was not.  And given that Weyand was convinced about it, you really do have to wonder what happened behind the scenes, especially when you consider that the research and the resultant published research paper was done as a result of a "deal" between the scientists and Oscar Pistorius' lawyers (in all this, don't underestimate the legal and PR machines in the background).  This is the main issue about the scientific process that I have questioned, along with what I explained in the previous post.

Too narrow a question and more selective omission

There is the argument that the CAS-proceeding determined a very narrow approach to the scientific question, which had really only one goal - to disprove the IAAF's findings.  In other words, the CAS process was not interested in the entire truth, but only in evaluating the evidence gathered by the IAAF.  And there's no question that the IAAF started off with a very narrow research question.

By extension, Pistorius' scientific team were interested only in the "truth" that would, among other things, eventually see them add distance runners to the control group until Pistorius looked similar to able-bodied athletes.  Effectively, the previous research had "set the bar" and they jumped over it, using the methods I explained yesterday.  A narrow finding got even narrower, and the whole truth did not emerge when it could have.  In all this, there was reason to suggest an advantage but the scientists did not make it known at the time, even if it was only for the purposes of debate.

Taking this into account, and adding in the fact that the research to clear Pistorius had very obvious omissions and false comparisons with distance runners when they knew what the sprinter-comparison would have revealed, you start to see that things really were not what they appeared to be with this "independent scientific process".  You may make up your own minds about what it means when scientists selectively leave out able-bodied sprinters and compare a sprinter to distance runners?  Or what it means when scientists recognize the possible advantage but fail to mention it at a hearing on advantages?  It strikes me as strange at best, manipulative bordering on dishonest at worst.

For a great read on the process and how twisted it seems to have been, David Epstein of Sports Illustrated provides the information, and I'd highly encourage you to read it here.  When you consider this, as well as the information we discussed yesterday on how the able-bodied group was manipulated to find

It then took 18 months, but when the paper was eventually published, it revealed a big split in the camp, and a group of seven was split into two - Weyand and Bundle on one side, arguing against Herr and co.  Eventually, it got to John McEnroe-like shouts of "you cannot be serious" in a scientific journal, and nothing came of it.  But it is this debate that I will end of with in this look at the science on Pistorius.  And then we can get on with enjoying the IAAF World Champs and on-track action.

The mechanical aspect of the debate

So far, we've seen that the IAAF testing found completely different mechanics and suggested less metabolic energy demand.  The Herr-Weyand study for the CAS hearing managed to find that Pistorius was "similar" to able-bodied elite and sub-elite distance runners.  Had they compared him to other sprinters, he was anything from 2 to 7 Standard Deviations different.

And then came this debate, which moves us from the metabolic to the mechanical - as I said in the first post, I believe the mechanical data provides the explanation for the metabolic and physiological findings of reduced VO2, and the implications for reduced metabolic demand.  And so that's the context of understanding this debate.

The "12-second advantage" - Weyand's calculation and the rationale behind it

Weyand and Bundle produced an article that explained the mechanical basis for an advantage, and concluded by estimating how much slower Pistorius would run if his carbon-fiber blades behaved like normal legs.  12 seconds was their answer, and that conclusion made their paper easy to dismiss for those who wanted to dismiss it.

So with hindsight, it may have been disingenuous to try to estimate the time advantage.  You can appreciate why they'd want to do it - it makes the debate more 'tangible', easier to conceptualize, but the problem is how it was done.  It took a few assumptions, and produced an advantage of 12 seconds, which was very easy for the likes of Herr to dismiss as too large to be realistic.  And that's fair enough.  But it shouldn't stop us from looking very closely at what Weyand is saying, how that number is estimated.  In order to understand where that number comes from, you first have to understand what it was that Weyand was arguing was the reason for the advantage, which is a good place to start.

A word on Weyand to begin with.  For all Pistorius' talk about how Herr and Kram and co were the best in the world, the truth is that Weyand is the world's leading biomechanist in sprint running.  Look him up on Pubmed and it's clear that he has done the seminal work on sprinting mechanics.  He is, you might say, an "F1 Driver" when it comes to mechanics...

And one of the key articles by Weyand is this one - a paper published in 2000 on how sprinters speed up, and it contributed the first key point in the debate.  Below is the key figure from that paper (sorry for not redrawing it - not enough time)

What you are looking at above are the swing times, in seconds, of able-bodied sprinters at a range of different speeds.  Swing time is the time spent by each foot in the air.  That is, it is the time taken from when the foot leaves the ground until when it next lands.

The runners are measured at a range of speeds, from 6m/s up to 11.1m/s.  Weyand adds Olympic runners measured on another occasion for comparison, but I'll disregard these three because there are questions about how accurately they are measured.  Besides, running at 40km/h is pretty much Olympic 200m level, and much faster than a 400m runner would run, anyway.  Pistorius ran at 10.8 m/s, so you don't need those Olympic athletes to make this case. 

The thing that should jump out is that there is no change in swing time as the runner speeds up.  Whether you are running at 6 m/s (21.6 km/h) or 11.1 ms (40 km/h), your swing time is pretty much the same. Even sprinting downhill, swing times don't get faster than this.

It's extremely tight, and that's crucial, because the key point about that is that in able-bodied runners, it is just not possible to swing the leg any faster than shown in the figure above, and so by the time we run 21km/hour, we are already at this "limit" for how quickly we can reposition our legs.  In Weyand's own words:
 "Clearly, with athletes with intact limbs, there's a lower limit to how fast they can reposition their limbs"
As a result, if you want to get faster, you have to do so by applying more force to the ground.  There's a downside to this - more force means more muscular work.  More muscular work means more metabolic energy cost, and two potential limits to how fast someone can run - first is the inability to generate that force, and second is the metabolic cost of doing the work, running at a given speed.  And that brings us to the theory of sprinting, and the Oscar Pistorius finding

Sprinting mechanics, and how Pistorius is "off the charts"

There are three things that limit the speed of a runner: 1) how quickly the limbs can be repositioned for the next step, 2) the distance traveled by the body while in contact with the ground and 3) the force applied to the ground in relation to body weight.

Above, I've shown that the evidence says that the ability to swing the leg is constrained regardless of running speed - 0.373 ± 0.03 seconds was the average ± SD.  Here's what Oscar Pistorius' mechanics look like compared to the able-bodied SPRINTERS when running at 10m/s in the CAS testing (about 400m pace):

So, longer contact times, shorter swing times, shorter aerial times, lower vertical force but not lower peak vertical force.  Using the statistical method that Herr and Weyand used for VO2, where anything more than 2SD different from able-bodied runners is different, it's clear that Pistorius is mechanically very, very different to able-bodied sprinters and crucially, these differences all provide significant sprinting advantages.

First, Pistorius has stride frequencies 16% faster than any athlete ever measured (and 9.3% faster than elite 100m sprinters - data not shown, and again, not worth including because of the measurement method).  It's a mass effect - the carbon fiber prosthetics weigh 3kg less than able bodied limbs below the knee, and so they can accelerate much faster, for less force.

The high stride frequency was the result of the speed of repositioning the limb.  That is, Pistorius' swing times are so much faster than any other runner measured, that Weyand described them as "off the charts".  At top speed, Pistorius has swing times of 0.284 s, which is 21% faster than sprinters - it's also 4 SD different from the other sprinters tested in this study, and 2.7 SD faster than the entire collection of sprinters tested in Weyand's lab in previous studies using the same methods.

Being able to reposition the limb so fast (11% faster than the fastest athlete in the group tested in the laboratory) has some major theoretical advantages.  In Weyand's own words:
"Oscar is off the charts. Clearly, with athletes with intact limbs, there's a lower limit to how fast they can reposition their limbs. With Oscar, if you make that lower limb twice as light, that moves that lower limit.  He repositions his limbs so fast that he doesn't need to get his body back up into the air so high like other sprinters, and that lowers the force he needs to generate.  The muscular forces he has to generate are less than half of what an intact sprinter has to generate to go the same speed." - quoted in SI article
Then there is contact time - Pistorius spends 14% longer in contact with the ground, which means the horizontal distance traveled during ground contact is higher (see the three factors limiting speed above), and it means that the force production required to run at a given speed is substantially reduced - it was 5.2 SD lower than the able-bodied controls in this study.  Interestingly, peak vertical force was lower, but not statistically (2SD) different from able-bodied controls.

How did he estimate 12 seconds?

So the next thing is to take the above measures and ask how did Weyand estimate a 12-second advantage?  There are a few assumptions that have to be made to do this, and as mentioned, I think Weyand did his own argument something of a disservice to not make a more "conservative" adjustment.  It's much the same as when I tried recently to explain how 6.2W/kg is a limit for cycling without doping.  You have to make assumptions, but if you make them sensibly, always making the assumption that goes AGAINST the thing you're trying to prove, then they're extremely valuable (I can elaborate on this more in the discussion if it comes up).

What Weyand did is move Pistorius' mechanics back into the able-bodied group.  That is, he looked at swing times and contact lengths and asked how Pistorius would run if those were "normal", or equal to the average of the able-bodied group.  So, the average swing time for the group was 0.359s so Weyand corrected Pistorius' swing times to that value. He also adjusted the contact length to 1.05m (to match the normal leg length-contact length ratio in able-bodied athletes) and average force produced during the stance phase.

The result was that he calculated that Pistorius' top speed would change from the measured 10.8 m/s to 8.3 m/s.  Next, using a similar method to that which Herr & Kram had used at the CAS to show that Pistorius DIDN'T have an advantage, Weyand estimated a 200m time of 27.3s and a 400m time of 61.7s, which was 12 seconds slower than his lab time-trial at the time of testing (49.8s)

Now there are two reasons why this 12-second estimate may be too high, and both relate to the inputs that estimate the performance.  The first is Pistorius' speed at VO2max.  During the testing, Pistorius' speed measured at VO2 max was 5 m/s (or 18 km/h, which is a sub-elite level), and this is factored into the prediction.  An elite sprinter would arguably reach a faster speed than this, and this increase (say to 6m/s, or 20% faster) would reduce the estimated time and thus the calculated advantage.  There is no question that Pistorius was less than in peak shape at the time of the testing - he fatigued at 15km/h after only 5 minutes, for example.

This has implications for both the findings of the study (Pistorius probably uses even less oxygen when highly trained than in the study, and that makes him even more different than was measured), and for the 12 second advantage.

The actual advantage - smaller than this, but nevertheless present

I think it's important to realize that the problem may be the INPUTS into Weyand's equation, and not the concept of the calculation.  If Pistorius had been 10% fitter, then those predicted times would drop, and the advantage predicted would be much smaller.  But given his state of training, it's actually not an unreasonable projection. 

The other issue is whether it's appropriate to correct Pistorius highly different mechanics to the average of the group.  It would perhaps have been better to correct them to say 2 SD from the average, so that he's still statistically similar, but at the extreme edge of the normal range.  If that had been done, then instead of adjusting his swing time to 0.359s, they would have made it 0.321s.  That calculation would produce estimates for performance that are closer to Pistorius' current times, but still faster.  I don't have the formula (or time) to make all these inputs now, but if the VO2max speed was 10% higher, and if the corrected mechanics were 10% lower, then the calculated advantage over 400m would drop considerably from 12 seconds.  And that is not nearly as easy to throw out as unreasonable.

Weyand didn't do this, and unfortunately the size of the advantage he did calculate gave ammunition to shoot the theory down.  That would wrong - the theory is correct, and the evidence based on mechanics is very strong, all that needed to change were the adjustments, the inputs to the equation.

So how large then might the advantage be?  Obviously, it's impossible to say, unless there is more testing.  That's not going to happen because Pistorius would never agree to it now - the science was only important until it cleared the blades for use.

I'd suggest another method that would give a good indication, using Pistorius' 400m and 200m race times, and then comparing them to other 200-400m athletes.  This works because the performance at one distance is a great predictor of performance at the other, and so when you look at this, compared with pacing, you get a good idea of how much he GAINS overall in a 400m race.  That is is, net loss would be canceled by net gain.  But not to leave you hanging, but I'll save this for another occasion, in the interests of time (it's a lengthy explanation of pacing strategy).

The rebuttal

Herr and the rest of the intial group produced a counter-point, and there were two main "points of attack".  One was video footage of other runners, to show that Pistorius was not really as different as Weyand claimed.  The problem is, you can't use normal video footage to make this case, the resolution is just too low to be accurate - that's the reason why I wouldn't include the Olympic or World Champion level runners in the control group.  Weyand did this in his subsequent response to Herr, and it saw the debate get a little side-tracked - the truth is that every finding in Weyand's initial report, and what I've summarized above, was produced in the laboratory, with very high resolution cameras, whereas Herr's rebuttal was based on inaccurate video footage.

Then Herr also reveals the hypocrisy of the statistical method used when it suited the desired finding earlier in the CAS process.  He writes:  
"Pistorius’ leg swing time of 0.284 s at 10.8 m/s is nearly 3 SD faster than that mean (It's actually 4 SD from the mean, but who's counting?).  However, leg swing times as low as 0.31 s for Olympic 100-m medalists at top speed have been reported"

So firstly, the Olympic runners were measured with low-resolution video, and Weyand responds to this with the example of the same athlete measured in the lab and on TV, and the TV times are 16% faster than the accurate lab times.  Clearly, you can't base an argument on TV footage.  The case I've made in the post above doesn't use TV footage, and is very compelling.

But more than this, having set up the 2SD requirement for difference, Herr now disregards it, and instead wants to compare Pistorius to the minimum value in the control group.   Even here, though, the difference is enormous.  The top graph in the post above shows some of the athletes who can be validly compared to Pistorius - yes, one athlete has swing times of 0.315s at top speed.  But Pistorius was 0.284s, and that is fully 11% faster than the next fastest swing-time ever measured - it's a whole 1 SD between the fastest swing-time and the next fastest. Weyand was quite correct in his response to say that "the double-artificial-limb value is not simply an outlier; it is quite literally off the biological charts".

The force production - advantage or disadvantage, cause or consequence?

The second big point of contention is the importance of the ground forces.  To repeat, Pistorius' average force production is 23% lower (5SD) than that of able-bodied athletes.  Hugh Herr argues that this reduced force production is a disadvantage, whereas to Weyand, it is a huge advantage (See quote above).

In trying to sort out this issue, the important point is that Pistorius' reduced force is present and measured during running at the same speed as the able-bodied runners.  That is, they're all going at 10 m/s when these huge differences are measured (see the graph above), and they persist at top speeds.  When you have fixed the speed, then the ability to increase the force is irrelevant.  In Bruggemann's correct words: "If we look at subjects running at different speeds, it’s logical to say that the higher the force, the higher the speed. But with all subjects running at a given speed, lower force is an advantage.”

On top of this, Herr looked at it 180 degrees backwards.  The 2000 finding by Weyand showed pretty clearly that the first limiting factor to sprinting was the ability to swing the leg faster.  This is "maxed out" fairly early, and then the ability to produce force separates those who can achieve Olympic-like speeds and those who cannot.  So there is an order - first you exceed the limits of moving the limbs faster, and then you have to apply more force to get faster.  And so when you have the ability to move the limb that fast - fully 11% faster than the next fastest person measured, and 33% faster than average), then the changes in force are the result.

As a result, the lower force production measured in Pistorius is the consequence of the reduced swing times.  The muscle force production requirement is thus lower - "half" according to Weyand, and that has some obvious benefits.  Add to this the higher energy return, the fact that less mass is being carried, and that carbon fiber does not fatigue during a 400m race, and you have explained why Pistorius uses much less energy at all speeds than other sprinters.

Advances in technology - have the blades really stayed the same?

The final point, before we get on to the IAAF World champs and leave this for now, is the issue of technological progress.  In a recent interview, Pistorius said the following:  
"My prosthetic legs have stayed the same for seven years, down to the bolts and the lining"

Hugh Herr, meanwhile was interviewed in a piece where he says that the "Cheetah blades have been available to athletes in their current form for 15 years, and that Pistorius has run on the same blades for the last seven years." 

Now, if you do believe that a company like Ossur, which operates five R&D departments, files more than 300 patents per year, and spends millions of dollars every year on product development (6% of total sales in 2007 was spent on R&D) would not change the blades over more than a decade, then you are more gullible than the Pistorius PR team would even have dreamed.

The reality is that technology evolves all the time - and in this particular segment, prototypes are produced, and tested by athletes who then have them customized.  Take the following, from an article where the journalist actually accompanies Pistorius (with his permission) to Reykjavik to test the latest prototypes in 2007:
"But last September [in 2007], Pistorius and Brauckmann went to Reykjavik to test prototypes designed for double amputees. The new ones, which Pistorius hasn’t debuted at a major race yet, make just one smooth curve, an arc of pure engineering.  Ossur’s R&D team met them at the company’s workshop and unveiled the prototypes. Brauckmann attached the blades to the sockets, and Pistorius walked around on them, testing the design".
So, in 2007, a prototype or two was tested.  Read further and you discover that each blade is customized for the athlete.  Add to this that these companies (and there are a few) regularly send their engineers to the athletes to 'test-drive' limbs that have a different stiffness, and you realize that the technology is not as stagnant as you may be led to believe.

Finally, I also know that a simple thing like changing the stiffness of the blade makes a big difference to  performance.  One case - a single-leg amputee tries out a range of different blades.  They are the same product, but with subtle differences in stiffness, curve etc.  The result is a variation in performance that is not hundredths or even tenths of seconds, but seconds.  That's a bigger effect than a year of training, than nutrition, I dare say, even doping will provide.  The simple reality is that the technology IS evolving, and there's no way to police it.

And to say, like Herr and Pistorius are both saying, that the blades are unchanged over 7 years is to say that the BMW that is driven by a friend of mine, a 2004 model, is the same as the 2011 BMW that he would like to upgrade to!  They're both BMWs, they both have four wheels, an engine and a steering wheel, but they're nothing like the same car.  So sure, the blades are the same.  But they're a world apart.

And the implication of this is that performance improvements, so coveted at the elite level, are now accessible through acts of engineering, subtle changes like stiffness, where there are many options within the same product.  Remember that a 0.1 second improvement is valuable in a 400m race.  0.5 seconds can be the difference between being fifth in your own country and top 10 in the world.  The margins are so small that it is unnecessary to talk about revolution - all that is needed is progression and prototypes provide this.  The CAS verdict applied to the blades that were used, but how is that even enforceable when you have subtle changes that can produce

Conclusion: Skillful but with an advantage

One final quote, again from the Wired article:
"To give me a sense of how they feel, Ossur’s engineers bolt a pair of Cheetahs to the back of two rigid plastic-and-leather motorcycle boots. I clamp in and trot across the room a few times. The Cheetahs seem to bounce of their own accord. It’s impossible to stand still on them, and difficult to move slowly. Once they get going, Cheetahs are extremely hard to control."
Legs that "bounce of their own accord" supports the conclusion of a "bouncing locomotion" made by Bruggemann in his research.  They must be very difficult to control and let me emphasize this point - Pistorius' unique performance is the result of his skill levels in using that equipment.  In the way that Roger Federer, Rafa Nadal or Novak Djokovic are elite because of their ability to use their equipment, or in the way that Sebastian Vettel is a superstar because of his skill with his equipment, Oscar Pistorius is skillful.

But every line of evidence - the metabolic, the mechanical, the physiological, the pacing - points to one thing - substantial advantage.  Of course, there is so much that has gone unanswered as a result of the narrow questions asked first by the IAAF and then by the Herr/Weyand research.  Would it not have been great to look at things like how much time may be lost at the start, whether running the bend is a disadvantage (I have data showing that Pistorius runs the bend faster than the straight)?  To test whether increasing the mass of the limb removes these mechanical advantages?  The narrowness of the research means we'll never know and there won't be more testing unless the IAAF demands it, because Pistorius has nothing to gain from discovering the truth, whatever it may be.

But the Weyand research, where Pistorius is off the charts, and the metabolic finding (which is explained by the Weyand conclusion, thus supporting it further) all say advantage.  Again, remember that this begins with the hypothesis that there is an advantage as a result of energy return and mass.  That hypothesis was confirmed by the metabolic measurements, and then explained by the mechanical differences.  It's difficult to see it any other way, as I read it.

Next up:  IAAF World Champs

And on that note, I leave this and look forward to the action on the track - IAAF World Championships start this weekend and there are countless stories that will add to the drama.  There is Semenya in the 800m, returning to World Champs after the 2009 saga.  There is Rudisha.  Bolt vs Powell.  Bekele vs Farah and Kenya. Galen Rupp and the possibility that either Kenya or Ethiopia might not get a medal.  There is Allyson Felix attempting a double.  There are dozens of great match-ups and stories and we'll cover them all in the next few weeks!


P.S.  A final point on the Herr-Weyand research, which I put as an Appendix of sorts because it's of interest but peripheral to the evidence...

Why was it not peer-reviewed?

One of the most common retorts to the Weyand argument about advantage is that it was not peer-reviewed.  That has come from both Herr and Pistorius, who dismiss it because of this failure to get it peer-reviewed.  The problem is, that research will never be peer-reviewed, because it belongs to BOTH Weyand and Herr.  They collected the data together, and so any research paper that gets written has to have all seven of the scientists agreement in order to be published.

Quite clearly, that was not going to happen - Herr was not going to put his name to a paper he so clearly disagrees with.  And therefore, it is not possible to be peer-reviewed.  That is the reason why the debate took place the way it did, as a point-counterpoint.  The irony then is that Herr (and thus Pistorius) are the very reason it isn't peer-reviewed.

Wednesday, August 24, 2011

The scientific evidence for an advantage for Oscar Pistorius

The second research study - what it really found about Oscar Pistorius

We may as well jump straight in with the continuation of the scientific summary of the research done on 400m sprinter Oscar Pistorius.  Yesterday, I described how the first round of testing, done at the request of the IAAF in Germany, found that Pistorius used 25% less oxygen during a simulated sprint, and that his running mechanics were vastly different to those seen in able-bodied runners.

That study led the IAAF to ban him from competing, and resulted in the appeal to the Court of Arbitration for Sport.  That brings us to the second research study, led by Hugh Herr, and, at the time, Peter Weyand.  Below follows an explanation of a key part of the paper they produced a few months AFTER the CAS hearing - the oxygen uptake question, which I introduced as being important in yesterday's post.  The timing is important because one of the first key points about the CAS-process is that the research was not peer-reviewed until after the decision was made, which contrasts with claims that the decision was based on peer-reviewed research.

With respect to the CAS hearing, there were without doubt procedural errors in the IAAF process of the scientific testing in Germany.  These are legal issues, pertaining to things like the timing of making documents available, inaccurate reporting of data in an IAAF summary, and dictating testing conditions.  This procedural dispute led the CAS to declare that "the manner in which the IAAF handled the situation of Mr Pistorius...fell short of the high standards that the international sporting community is entitled to expect from a federation such as the IAAF".  Unfortunately, it wouldn't be the first time that this has happened for a major sporting federation...

However, this is a look at the science, following on from yesterday, where I explained the specific scientific issues that were taken to the CAS panel, along with responses by Bruggemann and a few quotes from other biomechanists, as well as my views and interpretation of those points.

Today, I move on to the Herr research, which I believe is equally flawed.  But I'll go through it systematically, building up the main findings and figures, and then allow you to draw conclusions about what was done to come up with this overall finding: "We conclude that running on modern, lower-limb sprinting prostheses appears to be physiologically similar but mechanically different from running with intact limbs." (Weyand et al, 2008)

The metabolic cost of running - similar?

To begin with, one of the key points challenged at the CAS hearing was the measured reduction in oxygen use during a simulated sprint (figure shown to the right).  The problem is that during a sprint, metabolic energy is provided by a combination of oxygen dependent and independent sources, so Bruggemann provided only half the picture.

You would not be surprised to learn that in the CAS hearing, the IAAF focused on the biomechanical aspects of their research, and downplayed this particular finding, because their conclusion based on the measurement of oxygen use in a sprint was always going to be challenged very strongly.

And challenged it was - it would also not surprise you to learn that the response from Pistorius' research was to repeat the above test, but this time to measure oxygen use at sub-maximal speeds, because this provides a better indication of the metabolic cost of running.  And so this is what they did - Pistorius ran on a treadmill at a range of SLOWER running speeds.

The method used was to have Pistorius run for 5 to 7 minutes at a range of speeds, with 3- to 5-minute rest periods.  The starting speed was 9km/h (a very slow jog) and Pistorius reached exhaustion (unable to complete 5 minutes) at 15km/h (which is very slow, tellingly - Pistorius did this testing at a time when he publicly announced that he was untrained and unfit.  That this impacts on the results you'll see below is important).

Using measurements of oxygen use from Pistorius during these runs, they were able to calculate what is called running economy, or the volume of oxygen used per kilogram per kilometer. Think of this as fuel use in a car - the less oxygen you use per kilometer, the more economical you are.  Remember that the hypothesis based on one interpretation of the theoretical knowledge at the time would be that Pistorius would use less oxygen, and hence less energy, at a given speed because of the reduced mass and the increased energy return of the carbon fiber limb (see yesterday's post for the explanations).

(By the way, if you adopted the exactly opposite position based on the theory, then you might hypothesize that Pistorius would use MORE oxygen and more metabolic energy because of the demand for balance and the increased work required to control the limbs - this is what his coach, Ampie Louw, explained in a TV interview in 2007 for a UK news insert.  The point is that either theoretical claim can be tested by measuring oxygen use - it is a barometer for energy use, and will either be similar, in which case the theory is disproven, or will be different, in which case one of the theories will be proven, the other disproven.)

There are a few pertinent considerations here.  First, the Cheetah blades are built for speed (the manufacturer's own claim), not slower running, and so I would argue that testing them at these slow jogging speeds (9km/h is very slow) will provide a false picture, skewed in favour of finding a higher oxygen use.  However, even without that potential confounder, the data still provide some really interesting insight.

What is more crucial, for reasons that will emerge as we progress, is the vital question of who do you compare Pistorius' data to?  The answer must surely be able-bodied sprinters of similar performance levels.  That's because the literature shows that sprinters use more oxygen (or are less economical) than distance runners.  So the "control" group would have to be able-bodied SPRINTERS.  And this is where I begin, with four able-bodied sprinters compared to Pistorius (note - the development of the graphs below (which is Figure 2B in the research paper) does not necessarily follow the timeline of the testing, but it builds the argument and highlights the key issue)

The first graph, shown below, reveals the first finding - Pistorius compared to able-bodied sprinters at the same performance level:

So, Pistorius uses 17% less oxygen than the able-bodied controls, or 2.7 Standard Deviations less.  Without going into the stats, that's a big difference - generally, anything more than 2 SD is considered an "outlier", very different.  And so on the basis of this finding, Pistorius is very different to able-bodied sprinters.  This is not different to the 25% difference that Bruggemann found during sprinting, and it's not inconceivable that the 17% would be higher (approaching 25%, maybe?) at sprinting speeds, where the Cheetah blades are more effective, doing what they were built to do.  This first finding confirms the Bruggemann research.

Yet the paper concluded, you'll recall, that Pistorius is physiologically similar, and Hugh Herr was recently quoted as saying "It is not true that Oscar uses less oxygen than a person with two biological legs, although he is very economical".

The addition of the distance runners

So how do you get to that conclusion?  Answer - you add distance runners to the able-bodied population. Herr and co decided that in order to increase the size of the control group, the next group that should be compared to Pistorius was not more sprinters, but rather a group of sub-elite and elite DISTANCE runners, who had been measured in a study in 1995, thirteen years earlier in a completely different laboratory.

Once these distance runners are added, the following graph can be drawn:

So, with the addition of the distance runners to the control group, the gap between the sprinter Pistorius and the able-bodied runners is coming down - presumably this is a "good finding" if you're involved in this research and "want" to disprove the earlier IAAF study finding.

The difference in oxygen use between Pistorius and sub-elite distance runners was 6.7%, while Pistorius uses 3.8% LESS oxygen than elite distance runners.  However, statistically speaking, the differences are 0.8 SD and 1.3 SD to those groups, respectively, and so it can now be concluded that Pistorius is, in fact, not different to able-bodied runners.  Provided those able-bodied runners are elite distance runners, that is.

For good measure, they also add John Ngugi and Zersenay Tadese to the sample, and the graph is now complete, as found in the research paper (Figure 2B on Page 906):

Just a word on the Tadese value shown above: this is a study that I actually wrote quite a bit about back in 2007, and the main reason was because Tadese was the most economical runner in history, but there was something not quite right with that running economy value.  His economy, measured at 150 ml/kg/km has some bizarre implications - it means that running at world record pace for the marathon (2:56/km), Tadese would be using only 51 ml/kg/min of oxygen.  Take it from me, that's just not possible, especially when you consider that Tadese's VO2max was supposedly 83 ml/kg/min - his marathon world record pace would be an easy jog!  My point is - something didn't add up, and I'd be very cautious about accepting that Tadese value.  And this illustrates just why you should not take data from other labs and use it as part of your data set as was done - you simply cannot guarantee the validity of that data.

To do this, to borrow from other research, where methods are different, equipment is different, and athletes are different, is to violate a key concept in the control of science.  It's the same thing as if I want to test the effects of something like compression socks on muscle pain after running, and I make a few runners do a trial, and then compare them to a study done in a different lab with different methods.  Certainly, you will use other studies to explain your data and provide context in the discussion, but to borrow data like this is extra-ordinary.

Having said this, I can appreciate why it was done - the time was limited, and the research had to be done for the CAS panel.  The control group was small initially, and had to be increased in size.  So given the time constraint, I can appreciate that this would be an exceptional circumstance.  But the question is this:  Why compare a sprinter to a distance runner in one of the key variables (running economy) that is known to be very different between them, when data on sprinters exist for a more valid comparison?  At the very least, show BOTH distance runners and sprinters...

Why compare to distance runners, when data for sprinters is available?

The question is so important, I repeat it - why would Herr and co have chosen to compare Pistorius to elite and sub-elite DISTANCE runners, when the data exist for sprinters' running economy?  It's not as though we don't have the data for sprinters - it exists.  But the research chose to ignore these data, and instead focus on distance runners, both elite and sub-elite.  Why?  I hope it's becoming clear in your minds as you read this.

But before continuing, take a look at this sentence from the research article, in the discussion (pg 909):
"However, his values were 17% (2.7 SD) lower than those of the intact-limb 400-m specialists tested here and two or more SDs below the means reported for four other groups of subelite male sprinters"
In other words, the authors are aware of FOUR studies on sprinters that could have been used to expand on the subject numbers used in the very first graph I showed above.  Four studies that would have increased the size of the able-bodied control group and allowed a VALID comparison of a sprinter (Pistorius) to other sprinters, rather than elite distance runners.

One acknowledged consideration is that the sprinters in these studies are not elite, but then neither are most of those in the distance group used in their place.  The sprint data could, at worst, have been included in the analysis.  But instead, they chose to ignore the sprint data on athletes who were, at the time, at more or less the same performance level as Pistorius.  Rather, they presented the distance data, which conveniently supported the ultimate finding of physiological similarity.  Perhaps the comparison with other sprinters produces a finding that you'd rather not show...

The graph that compares sprinters to Pistorius - the real finding and comparison

So I went and found the four studies in question, and I've redrawn the graph, this time showing the oxygen use of Pistorius compared to other sprinters and middle-distance runners, rather than elite distance runners:

So, that graph looks a little different to the one shown above, the one that was eventually published in the research paper (Fig 2B), comparing the sprinter Pistorius to the elite and sub-elite distance runners.  Here, when you compare Pistorius to sub-elite sprinters, you get a very different picture.  I've shown in red below each bar the difference in percent between Pistorius and these sprinters, and in black, the difference in Standard Deviations.

So 17% or 2.7SD is the Weyand et al finding (comparing Pistorius to performance matched sprinters).  13% or 7.2SD is the difference to 400m sprinters (performance time 50s). It's 3.2 SD to 800m runners, 5.1 SD to 1500m runners, and overall, Pistorius uses 14% less oxygen than able-bodied sprinters and middle-distance runners.  That's 2.3 SD and a difference that, according to the definition set out by Herr, would have led to the conclusion that "Pistorius is physiologically different"  And importantly, it's a difference that strongly supports the hypothesis of advantage.

Again, these are sub-elite athletes (50sec 400m time, for example), but they do include middle distance runners who would be expected to have better economy than sprinters (remember, Pistorius is a 200m-400m sprinter), and they are close to the performance level achieved by Pistorius in the actual testing protocols (they actually exceed his level - remember, he hits a peak sustained speed of 15km/hour - some of the above runners were measured at 20 km/hour).

Conclusion - look at what is included as well as what is not

So the point in all this, I would hope, is obvious.  The selective addition of distance runners to the able-bodied group allowed the physiological differences to disappear (statistically speaking).  Meanwhile, selective omission was happening - there were at least four studies on sprinters that would have confirmed the Bruggemann finding, and even the Weyand 2008 finding that Pistorius has significantly different physiology and metabolic cost compared to other sprinters.  This would go a long way to confirming the initial hypothesis, and so it's not a trivial matter at all - it is in fact the crux of the issue.  The question is why make this selective addition and omission?

One answer may provided by the background to the research.  Pistorius has the Bruggemann research, he knows the methods and the results, and knows why he has been banned.  He now has to cast doubt on the Bruggemann research, showing the CAS that there is insufficient scientific evidence to ban him.

The first point to challenge for the CAS hearing, arguably the "weakest point" in the IAAF case, was the issue of energy use, or metabolic cost of running.  So the researchers Pistorius works with, one of whom is a big recipient of funding from Ossur, who make Pistorius' blades, are tasked with disproving the Bruggemann findings.  That means one thing - show that Pistorius uses similar volumes of oxygen compared to able-bodied runners.

Unfortunately, he doesn't.  At least not compared to sprinters, who train like he does, who share the genetic make-up of being a sprinter rather than a distance runner - he's 17% different despite everything being in his favour - he's untrained, he's running at slow speeds on equipment designed for higher speeds.  I dare say that three months of training would reduce Pistorius' values even further.

But when distance runners are added, the control group changes sufficiently so that even though Pistorius uses less oxygen and energy than them, he is statistically similar, and it is concluded that he is physiologically similar.

CAS accepted this (which defies belief, but anyway), and so the key barometer in the debate, the key variable that allows one to evaluate whether the theory is correct regarding the reduced energy cost of running on the carbon fiber blades, suddenly appears questionable.

Go right back to the hypothesis - either Pistorius has a metabolic advantage because of the reduced mass and the elastic energy return, or he doesn't.  Measure the oxygen used, and it will decide for you - the measurements of oxygen used confirm the metabolic advantage - across a range of speeds, from barely a jog to a 400m race, Pistorius uses significantly less oxygen than able-bodied sprinters.  Even dipping into previously published literature confirms this.  My take - hypothesis proven.

The mechanical debate and the "10 second advantage"

There is still the issue of mechanical advantage.  But it's late here in SA, and that is an issue for another day, when I'll look at the split that occurred between Pistorius' own scientific team, leading Weyand to publish a letter to JAP suggesting a 10-second advantage.  That is the final piece of the puzzle.

Thanks for the comments to yesterday's piece, it's good to inspire debate and as mentioned, in all this, there's allowance for disagreement.  I mean, we can't even agree on something as basic as whether dehydration causes heatstroke, I don't expect consensus on this.  But I've seen more ambiguous data, that's for sure - this is, I suggest, pretty clear cut.