800m: Caster Semenya & Robby Andrews

800 m musings - Caster Semenya, Robby Andrews and contrasting pacing strategies

Thanks all for the huge response to the previous post on barefoot running.  I can think of only one other topic that has produced the kind of discussion we've seen in the last few days, and those were our posts on Caster Semenya, who I discuss a little more below.

Some of the comments and discussion on the barefoot running issue were extremely enlightening and if you're eager to learn even more, then going through that discussion is as enlightening as any article, so thanks again and do take time to browse the discussion if you haven't already - we'll outsource it as a post all by itself!

800m - Caster Semenya's performances under the spotlight

Today though, I wanted to discuss the 800m event, specifically to highlight two really great talking points in the last week or so, beginning with Caster Semenya.

Semenya was always going to be one of the most scrutinized athletes in the world, her return to competition after a gender controversy bringing human interest, athletic interest, and scientific interest angles.

Ours is all three, but primarily the scientific and athletic, and so we've been watching closely to see how she performs now that she's had a full off-season to prepare and build to competitive shape.  Her comeback was actually in 2010, and she even won a few races in Europe, but that season was hampered by sporadic training caused by injury and the doubts over whether she would be able to compete.  The same can't be said now - she's known since this time last year that she would be eligible to run.

So her 2011 performances were always going to be the subject of discussion.  This situation became inevitable when Semenya, her lawyers and the IAAF decided that no public announcement of what happened in the aftermath of Berlin would be made.  The result was that the whole world knew there was a question mark, but it was followed by speculation and assumption, rather than an answer, even a basic one.

Speculation no matter what the result - the catch-22 for Semenya

As a result, every race for Semenya would be followed by one of two responses.  Either she would win convincingly, and the world's athletics followers would say "She has an unfair advantage, they obviously didn't change anything, and now thanks to her lawyers, no other women can even compete".  Or, if she didn't win her races, the world would say "This proves that she must have had surgery or treatment".   A catch-22 for Semenya.

But now a third response has appeared - she doesn't win, and everyone says she is losing on purpose.  And that's been the case after her first two races - the came second in Eugene a week ago, and third in Oslo on Thursday, and the talk on athletics websites is that she is deliberately losing races so as to avoid attention and further discrimination. 

No matter how you look at it, it's an impossible situation to be in.  And from the observer point of view, it's similarly difficult.  It would be great to just leave it alone and let her run, but the way things unfolded, that is basically impossible, because people want to know that they are watching a fair race, a competitive event.

So the current speculation was inevitable and this was exactly the reason we argued many times that she (through her lawyers) needed to make some kind of statement to at least assure people that something had changed.  Not the full medical details, those are hers and should be confidential.  But something along the lines of "I have worked with the IAAF and a team of medical professionals over the last six months, and all parties are satisfied with the resolution and progress, and that I can now compete fairly as a female.  I look forward to running and and competing again".

The IAAF could have made a similar statement, supporting that their experts were confident that she no longer had an unfair advantage, and perhaps some of the speculation would have been dealt with.  It would not have removed doubt or controversy, but at least there wouldn't be a shadow hanging over every performance, doubt that she's cheating by running too SLOWLY when she could dominate the event.  And if you think this is an isolated opinion, it's not, I suspect many people are wondering "why is that athlete wearing red trying NOT to win?"

I don't know the answer to this - I would find it difficult to believe that any athlete would deliberately finish second when they could win by a small margin (in a relatively slow time of 1:58.xx too - it's not as though she'd be running 1:54 to win every race).  And to finish third when they could finish second?  I find it difficult to believe, so I'd almost want to give her the benefit of the doubt.  Also, I'm not sure she or her team is that calculating, but perhaps I'm naive.  She is currently 4 seconds off her best, around 3.5%, which is a big distance off your best.  But that could mean one of three things - training hasn't gone well, she's running slowly on purpose, or she had treatment and the 1:54 from 2009 is now never going to be possible.

Also, I've seen her race BEFORE the controversy, and she looked pretty much the same as she does now, even when losing.  For example, in her World Junior Championships in Poland in 2008, she finished 7th in her heat, and looked much the same as she does now.  It may be that she just looks like that, that she never seems to be straining - short, chopped stride, no major upper body rotation - it would easily look like someone wasn't working hard enough.

But, then I see her race in Eugene and Oslo, and I can appreciate what people are saying - she led for 700m in Oslo and then in the final straight, just seemed to coast through to a third place finish.

But, you can see for yourselves if you haven't already.

First, here is the race in Oslo:




And here is the race in Poland, 2008.  As an aside, note the difference in her physical development from 2008 to when she won the World Title in 2009 in Berlin.  Truth is, if it hadn't been for controversies about gender, there'd have been a lot of people speculation about doping, such is the cynical age of elite sport we live in.



Your thoughts?  No matter what one believe, it's a difficult situation - the more I've written about this, and spoken about it, the more I've realized the problem of intersex conditions in sport is basically insoluble - there's no solution to satisfy everyone.  Of course, Semenya's case was handled so poorly and unfairly for her, and her response to it has been admirable.  But for the sport, the questions have to be asked.

Robby Andrews - great finish, interesting contrast in pacing

On a more racing-specific note, here is a fantastic men's 800m from the NCAA championships over the weekend.  It's fast, and competitive, one of the better finishes you'll see in an 800m race.  Watch the clip before reading on, spoilers to follow!



So the interesting thing for me is the pacing strategy - I'm biased, but I read quite a bit into it!  And the guy who ends up second, Charles Jock, runs a first 400m in 49.85s.  Super quick, and followed by a second lap in 54.90s.

Now that's a huge positive split - 5 seconds, which I don't believe is optimal.  Robby Andrews, who catches him, runs the first lap in a low 51s, which means his second lap is around 53.5 seconds.  That's a far more reasonable balance to the race, much more in line with how the best 800m performances have been recorded.

But the point I'd make is that Robby Andrews' super quick finish (which is amazing, don't get me wrong) only appears that fast because the rest of the field was far too fast early on.  To give you more numbers, Jock was recorded at 1:17.1 at 600m.  That means after a first lap of 49.85s, his next 200m took 27.3s. And his final 200m took 29.65s - he was getting progressively slower.

So was Andrews, to be honest, and it's a safe bet that Andrews was a little quicker than 27s to the 600m mark.  But then Andrews finishes with a final 200m of about 26.5 seconds (assuming he's ± 1 second down on Jock at 600m), compared to Jock's final 200m of around 27.65 seconds.

In other words, Andrews just slowed down the least, and that one second gap which looked so enormous at 200m to go, was overcome as a result of a better overall pacing strategy, combined with a huge slow down for the rest of the field.

Pacing strategy is not a precise science, at least with the knowledge we currently have.  But a + 5 second differential in an 800m suggests to me too fast a first lap, whereas the + 2 for Andrews is a much more controlled, and probably closer to optimal, performance.

But a great race, nevertheless.  Can Andrews go faster?  Probably.  Can Charles Jock?  Definitely, because he should have a big improvement there if he gets the pace right!

But more on pacing in the series coming up when I'll share the video of my presentation on the subject from the recent ACSM!

Enjoy the Diamond League!
Ross

Early vs Late Specialization: When should children specialize in sport?

Early vs Late Specialization: When should children specialize in sport?

There is no single pathway to success in sport.  If there were, we wouldn't be able to compare the stories of Chrissie Wellington, who discovered her remarkable talent late in life but went on to dominate IronMan Triathlon within a few years, to that of another endurance athlete, say Floyd Landis, who began cycling at school, with a single minded focus that took him to the professional level many years later.

There are countless cases of both examples, not only in endurance sport, but in skill-based sports - cricket or rugby players who "arrive" in their 20s, compared to the "prodigies" who are ear-marked for success from their early teenage years, or even earlier.  I am sure that in your own country, you can instantly think of one example of each.

If it took starting at the age of 4, with a parent driving a child to train for hours a day (think Agassi, Woods), then we wouldn't have cases like Roger Federer, who showed exceptional tennis ability very young, but did play other sports (on this note, Federer is reported to have begun at 6, but played football and tennis until he focused on tennis at 12 - this is still young, as we'll see later, but it's not nearly as early as other cases of tennis players.  Compare Agassi, who spent hours a day practicing at 6 years old, and who even played a match for money at the age of 9, at his father's "request")

But is there an optimal time to begin specialization in a particular sport?  This is such a loaded question that I can't possibly answer it, or even begin to cover it in one post.  So with that question begins a series of articles where I'll look at some of the evidence for whether young athletes who specialize very early on are more or less likely to succeed than athletes who delay high training volumes, competition and specialization in sport.

Without wanting to be too prescriptive, I think the following sub-headings needs to be addressed in a series:

1. What do elite athletes do?  Is there evidence to say whether early or late specialization is better?
   
2. What does science (that is, me...!) make of the 10,000 hour concept that that it takes 10,000 hours of deliberate practice to become an 'expert'? 
   
   Really, what this gets at is whether there is such a thing as "talent" or whether hard work and practice allows anyone to succeed.  It's the Coyle, Syed and Gladwell argument in Talent Code, Bounce and Outliers.  But what does physiology make of it?
   
3. What is the concept of Long-Term Athlete Development (LTAD)?  Where are its strengths, and where are its shortcomings, both practically and physiologically?
   
4. What are the implications of all this for coaches, parents, and young athletes?

So with that in mind, let's get started towards trying to answer that question.

Early and Late specialization:  Introducing the concepts

So we begin by looking at some evidence for what elite athletes do, and for that, I'll focus on a specific research paper called Late specialization: the key to success in centimeters, grams, or seconds (cgs) sports. (I linked to this paper on our Twitter feed on Monday, and I'll do a similar "article of the week" every Monday, so if you haven't yet followed us on Twitter, you can do so now!)

The title of the paper kind of gives away its conclusion, but don't worry, there is a lot more to it, including my conclusion that the paper does NOT in fact make this discovery, and there's something much more complex going on.

Here is a systematic breakdown of the paper, looking at the main research question, the rationale behind the research, its findings and how they might be interpreted.

The research question and rationale

The paper aimed to sort out which of two models for developing elite athletes was most effective in producing elite performances.  Those two models are summarized in the diagram below.  But before we begin, we have to define specialization.  In the paper, it has a rather clumsy definition, where it's a hybrid of being defined as a focus on a specific sport, as well as being measured in hours of practice in that sport.

In many cases, specialization and training volume will be related - the more you focus/specialize, the more time you have for that sport.  For example, a 15-year old with 2 hours a day to train will train more for Sport A if they are specialized than if they split the 2 hours between Sport A and Sport B.  However, this is not always the case - the same 15-year old can be "diversified" and do both sports, but still do more training in each than the specialist if they sum their time - A + B might equal four hours a day, not necessarily two.

To me, specialization should be measured as the number of hours spent training for Sport A relative to the time spent practicing for Sports B, C and D.  Someone who only practices tennis for one hour a day is more specialized than someone who trains tennis for two hours, but also plays football for an hour a day.  In the literature, however, there seems to be confusion around this, and specialization is not only "single focus", but also training time.  In other words, it's "specialization plus time practicing", and in the paper, I feel this is confused, and impacts on the conclusion.  Bear this in mind, because it will come up later...

So on your left is this model of "early specialization", where an early focus on a sport is recommended.  This is motivated largely by the framework that it takes so many practice hours to become proficient, and so you have to start young, and focus young, in order to accumulate them.  This is the Ericsson argument, and if you've read Bounce or Outliers, you'll know of Ericsson - he did a study on violinists in Berlin and found that the outstanding violinists had practiced for almost 10,000 hours, compared to only 8,000 hours for the "good" and 4,000 hours for the "normal" violinists (the ability of the violinists was assessed by the professors and teachers, in case you were wondering).

That study led to this 10,000 hours concept, which has since been applied to all kinds of skills, including sport.  There is an inherent problem with this, because sport is not the same as playing a violin in that there are without doubt physical attributes that training cannot change but which determine one's "ceiling of ability" in most sports.

The most obvious (bordering on ridiculously, in fact) example is that if you stand 1.50m tall, you'll never be a basketball star, even if you accumulate 20,000 hours of practice.  Your genetic make-up eliminates some of your options, it determines your ceiling especially when physiological characteristics are so significant to success, and then training helps to optimize how close you get to reaching your ceiling.  That's why no one succeeds without some training, but without question, some have more "talent" for a specific sport than others....  Whether the same is true of a skill-sport like tennis is debatable.  This is a great topic, but not one for today - that's why I'll set it aside for a future post as part of this series.  Let's leave this as saying that this kind of thinking drives the early specialization model.

On the negative side, there is also evidence of higher attrition rates with early specialization, and also potential negative health outcomes.  The issue is whether a young athlete who specializes at 9 or 10 is likely to continue with the sport beyond say 18, and there is some evidence that the answer is no.

On the right, the contrasting model is Early Diversification.  Here, children play a number of sports, the theory being that they develop a diverse range of skills, which are transferred across sports.  The proposed upside is that it promotes intrinsic motivation (let the child choose for themselves) and balance through increased exposure, and also ensures longevity.  The downside is that it may be too late, and by the time the person reaches adulthood, they may never overcome a potential late focus on training for a specific sport.

The only way to differentiate is to ask the question of elites, and that's exactly what the study did.

The method and findings

This kind of study is usually done by looking backwards in what is called a retrospective design.  Athletes are given questionnaires asking them to recall how much time they spent training each year.  Your alarm bells might be ringing, and rightly so, because this is a fundamental problem of this kind of research - it's reliant on memory and we all know that this is not infallible - can you remember how many hours a week you spent training in 2003?  The authors of the paper acknowledge this and they use some methods to confirm the memory of the athletes they interview, and conclude that the recall is reasonably good, given the limitation.  What will really help is a 20-year prospective longitudinal study, which I'm sure is on the way at some stage in the future.

The athletes interviewed in the study were high-level Danish athletes who were split into two groups, Elite and Near-Elite.  Elite athletes were those who had achieved Top 10 placings in World and Olympic competition or podium finish in European competitions, which is pretty impressive.  I'm looking at repeating this study here in South Africa, and if we set the standard at Top 10 globally, we'd be lucky to get 20 athletes!  The Danish got 148.  In the Near-Elite group were 95 athletes who hadn't met those criteria, but who were still on the Danish sports programme.

The athletes were then given a questionnaire looking mainly at how many hours a week they practiced, from the age of 9 up to the age of 21.  They also had to report what other sports they did and when they reached certain "milestones" in the sport, such as first international competitions, when they began intense training and when they reached the elite level.

The other very important thing to point out is that they only sampled athletes in what are called CGS sports - these are the sports measured in Centimeters, Grams and Seconds.  Think Rowing, swimming, athletics, kayaking, weightlifting, sailing, triathlon, cycling.  This is vital, because this study is NOT going to allow us to answer whether a tennis player or a golfer should start younger.  It also looks at sports that are typically more favoured by later specialization, because in general, peak performance age in these sports is in the mid to late 20s.  Sports like diving and gymnastics, on the other hand, are characterized by a peak in the late teens, early 20s, and that's a significant point to make.

Below is a summary of the main findings regarding cumulative training time, with a short explanation beneath it (it's fairly self-explanatory)

So four major findings.

• The first is that the Near-Elite group had actually gotten an earlier start than those who would go on to be elite - by the age of 9, they're 160 hours of practice time AHEAD.  
• That difference persists up to the age of 18, by which time there is no difference between the Elite and Near-Elite athletes.  
• Then, at the age of 21, the Elite athletes have pulled well clear, with about 1,100 hours MORE training than the Near-elites at that age.  
• And finally, there was no difference in the number of months spent on other sports - 63 months for the elites, 62 for the Near-Elites.  In other words, during the 12 year period of sampling, both groups spent just over 5 years in total practicing in other sports.  What is not reported is how those sports were spread out - were they done predominantly from 12 to 15, were they done for 7 months a year or all at once?

The practice trajectory:  When should the training volume be ramped up?

The above table (and the main table of results in the paper) are however incomplete.  What is really of interest is to track the practice time per year in these athletes.  For some reason that wasn't presented in the paper, but it's easy enough to do given the results, and so below is my re-analysis of their data, looking at what I would call a "practice trajectory":

So this plots the average number of practice hours PER week over time in the two groups.  Elites are shown in the beige, the Near-Elites in blue.  Quite clearly, they follow different trajectories.

• Up to the age of 9, as we said, the athletes who will go on to be Near-Elites do more than twice as much practice - it's an artificially low number, of course, because there's probably zero training up to maybe 5 or 6 on average, but it had to start somewhere!
• From 9 to 12, Near-elites do 2 hours a week more than athletes who will go on to be Elite
• From 12 to 15, Near-elites remain ahead, and the result is that by 15, they'd accumulated about 850 hours more practice than the Elite group had done
• Then from 15 to 18, it changes.  Here, the Near-Elites began to practice less, while the Elite group continued, increasing to almost 2 hours a day on average.  That shift is what causes the cumulative practice time at 18 to be equal between the groups, as we showed in the previous figure
• From 18 to 21, more of the same - the Elite group continues to spend 14 hours a week in practice, while the athletes who will go on to be Near-Elite drop down to just under 7 hours a week

So quite clearly, they follow very different pathways, and end up in different locations - one group goes on to be in the Top 10 globally or Top 3 in Europe, the other doesn't quite make that level.  They may yet, of course, the study was simply a retrospective look of a sample.

The authors then made five major conclusions. 

1. Elite athletes specialize later in their career.
2. Near-elite athletes pass through “milestones” sooner than elite athletes (I didn't go into this data, but the summary is that the athletes who go on to be Near-elite begin sport younger, train hard sooner and enter international competition around 2 years earlier than athletes going on to be Elite)
3. Elite athletes enter international competition older (as for above)
4. There is no difference in the time spent on other sports (remember, 62 months vs 63 months over the recall period)
5. "There is no delay in the athletic development that cannot be made up later with late specialization"

Some arguable conclusions, and what the study REALLY shows

Read that last conclusion again, for it is perhaps the most important one in the paper:  "There is no delay in the athletic development that cannot be made up later with late specialization".  I actually disagree subtly with this conclusion.

To me, the primary finding of the study is that success and performance in these CGS sports is NOT determined by how much TIME is spent training as a child, and that increasing the training volume later (after 15) is more than able to make up for time NOT spent training when even younger.   

As for the issue of specialization, that's a conclusion not supported by the results!  The time spent on other sports was the same - it may have followed a different pattern, but this wasn't reported.  All we know is that both groups did around 62 - 63 months of training in other sports over this period.  Specialization, defined as a single-focus on a sport, has nothing to do with ultimate performance, then.  It's more about time spent at different ages, and that "practice trajectory" I showed in the above graph.

However, in the interests of your time, and mine, I'm going to leave it overnight, and pick up this discussion again. Let's just say that this study was much more focused on training time in the final chosen sport, and it makes quite a nice case for delaying high training volumes until the mid to late teenage years.  Effectively, you need to replace "specialization" with "high training volumes" and then you have the real finding of the study!

And that's where the discussion will resume tomorrow!  That, and also we'll look at some of the reasons why that graph of practice time would look like it does - it may not be what you think!

I'm sure there will be comments and feedback, and as always, it's most welcome!  Join us tomorrow for more on this paper, and the issue of specialization vs training volume.

Ross

Biological passport: Effective fight or futile failure?

The Biological Passport Part 2: Effective fight or futile failure?

So last week I had a first look at some of the science of the biological passport, and specifically the legal aspects of how that science is interpreted.  Thanks for the great discussion to that post, and especially from those who "dropped by" to share some insights from the passport team itself!  As is often the case (always, maybe), your discussion is twice as good as the original post!

Also, I'm unashamed to admit that on this particular topic, I can't even deliver satisfactory answers to many of your questions!  It's clearly a mighty complex topic, and one that discussion will help grow understanding of.

So today, we forge ahead with what I ended off on, and that it is the question of whether the passport is worth the effort, or whether the cyclists are able to "dodge" it so effectively that it's just another attempt by the doping control to catch the dopers from behind.

The origin of this debate come from many sources.  There is certainly a perception, or a swell of opinion, that because the passport sets such stringent limits, it "misses" or fails to detect when doping has occurred.  People point to the lack of convictions as proof of its ineffectiveness.  Hopefully, in that last post, I was able to explain or introduce why this very strict probability limit is applied.  Before we can continue, I must recap very briefly (I won't repeat that mammoth post, don't panic!):

The Biological Passport concept in a flash

• The passport concept is that regular measurements of certain blood variables, like the percentage of reticulocytes, hemoglobin, and a calculated score called the Off-score, can point towards blood doping
• The principle is that it is possible to detect the effects of doping without ever having to find the drug.  To gather the evidence, so to speak, rather than having to find the smoking gun in the hand of the accused!
• Each rider is measured throughout the season, and their values set what you might call "basal levels" because we know that when it comes to blood, there is only so much variability from one test to the next.  That is, you don't go from a Hb concentration of 160 g/L to 190 g/L without suspicion.  
• So a trace of a rider's values that is developed longitudinally (over time) should NOT resemble a mountain range with huge peaks and valleys!  The key point here is that each rider's values then set a range of probabilities for what a subsequent reading should be - the athlete is his own reference.  
• The key point, legally, is that because of biological variation that is NOT due to doping (pathologies, for example) and because of analytical errors (they do happen), there are multiple layers of security built in.  They include:
• A probability limit of 99.9% which means that a value outside of these boundaries (an upper and lower boundary) is correct 999 times out of 1000.  Put differently, the chance of finding a "strike" or suspicious result in someone who is NOT doping is 1 in 1000 samples.
• An expert panel who review the results from the ABP (Athlete's Biological Passport) software, and only initiate further discussion if multiple variables are over the limit
• Once initiated, no case is opened until the expert panel requests an explanation from the athlete.  If this is still deemed inadequate by the panel, then they go to an official enquiry.  At this stage, a disciplinary procedure against the athlete could be initiated based on the presumption that a prohibited substance or method had been used - the cases of Pellizotti and Caucchioli represent CAS verdicts on this process, and they were positive

To illustrate, below are two actual samples off the Biological Passport software.  The top one shows a clean, non-doped athlete, the bottom shows doping, with an athlete who has a total of 7 "strikes" against him (1 for Hb, 3 for the Off-hr score and 3 for Ret %).  For more explanation of these strikes and the upper and lower probability limits you can see, refer to my previous post

Source: Zorzoli & Rossi, 2010             

Too "conservative"?

So that's it in a nutshell - the issue now is whether those "security levels" render the passport ineffective.  Is it doomed to be another control that clever athletes dodge with ease or has it had an impact?  For example, if the probability limit was set at 99%, then far more samples would be classified as "strikes".  It would also mean a 1 in 100 chance of false positives, the downside. 

I wrote last time that I feel the answer is that it very definitely HAS had an impact on the sport, and I'll describe why I believe that below...

An effective deterrent - the absence of convictions is not a symptom of ineffectiveness

Allow me an analogy.  Say you have a stretch of road that is known to be a high accident zone as a result of speeding - guys hit 100 mph in the 70 mph zone.  Authorities might decide to install cameras to catch people speeding.  They might estimate that in a given week, an average of 500 cars speed through this section - it's impossible to know the precise number, because it can't be documented.  Having installed cameras, they review the statistics and find that they are now catching 2 speeding cars per week.  A failure? Are they looking in the wrong place? Not necessarily, for the obvious reason that as soon as drivers know that the risk has increased (provided they also believe that the punishment will be enforced if they offend, of course), they modify their behaviour accordingly.

This is an obvious and simple example that just because the passport is not catching doping cyclists, it may actually still be exerting an effect on the professional peloton as a result of what I would crudely describe as "fear" that this new system can catch dopers.  Doping behaviour would thus be modified as a result of awareness, and the end result is that authorities might catch FEWER transgressors, but should still feel content that they're getting a problem under control. 

Will people still speed?  Of course.  But will they speed less severely, and try to speed only when not being observed?  Yes, and the end result is positive.  Similarly, cyclists will dope, there is no doubt of this.  But they will be more careful, and that has positive consequences.

Evidence of effectiveness - a fascinating graph

But, you are not going to just take my word for it (nor would I expect this!), so let's look for some evidence.  If the cyclist is changing their behaviour in response to the increased chance they will be caught, then you can expect to see changes in the markers that reveal the EFFECTS of doping.  In other words, you apply the Biological Passport concept, and investigate whether things are changing.

So here is a graph that gives me great confidence and hopefully some cause for optimism (thanks to Dr Mario Zorzoli via Prof Yorck Schumacher for steering me in the direction of this graph and allowing me to use it - the reference for the paper is at the end of the post for those who want it)

It shows the percentage of blood samples measured in professional cycling that had UNUSUAL reticulocyte percentages.  You might recall from my last post that:

• a LOW reticulocyte percentage indicates that there are fewer immature red blood cells because red blood cell production has been switched off - this happens after the infusion of RBC, or blood doping
• a HIGH reticulocyte percentage indicates that there are more immature RBC, and this happens because of removal of blood or the use of EPO, which both stimulate RBC formation
• a 'normal' or physiological range for reticulocyte percent is 0.5% to 1.5%.  Anything outside these is suggestive of doping

Source: Zorzoli & Rossi, 2010; Zorzoli 2011           

So, what are you looking at?

The green blocks show abnormal samples where reticulocyte percentage is HIGHER than normal - either 2 to 2.4% (light green) or above 2.4 to 5% (dark green).  Remember that a higher reticulocyte % means more immature blood cells, suggesting EPO use or blood removal.  So quite clearly, in 2001 and 2002, you had a high percentage of samples that suggest EPO use - between 9% and 11% of all samples, and 80 to 90% of suspicious samples.  No surprise there.

Then comes the introduction of the urine test for EPO in 2002, which I've shown with a blue line.  Suddenly, things change - now, you have much larger pink bars.  The pink represents LOWER than normal reticulocyte percentage - either 0 to 0.2% (dark) or 0.2 to 0.4% (light)

So clearly, the EPO test changed things - from 2003 to 2007, between 6% and 10% of samples had low reticulocyte %, and these tests make up 80 to 90% of the abnormal test results.  Remember, this suggests blood doping, and a shift in practice after the EPO test was introduced!

Introduction of the Passport and another change

Then comes the Biological Passport, shown by the red line in 2008 and a substantial drop in the total number of tests with abnormal reticulocyte %.  This is clearly a good finding, because only 4% of all tests have unusual reticulocyte percentages, a drop from 14% in 2001.  That's an enormous impact, and while it does not prove that doping is reduced, it does suggest that the Biological Passport has had a measurable and expected impact on the sport.

And there is the "elegant" timing where the introduction of a test first shifts the trend from high ret % (EPO use driving RBC formation) to low ret % (blood doping which suppresses RBC formation) and then seems to bring it right down.  This strongly suggests that professional cycling has adjusted its behaviour in order to avoid detection, not once but twice - the first was a change, the second a reduction.  The threat has therefore induced change.  But there is more to this - it's linked to performance, and that's something I will pick up below.

But first, an important question.  Does this prove that doping is not happening?  Of course not - riders are smart, they micro-dose, they mask doping by using EPO to switch RBC formation back on when infusion would normally switch it off.  There is still corruption, and no science, however powerful will be 100% effective if there is any hint of cover-up.  Going back to my speeding analogy, people will always speed, but instead of hitting 100 miles an hour, they pull back to 80 miles an hour, and they "select" when to speed.  Traffic officials will still accept bribes, officials will cover up some cases, but the overall trend would still be positive.

I would propose that a similar thing has happened for cycling.  There is almost certainly doping, and I will remain a skeptic, but I'm also optimistic that this new method, which will continue to be developed and improved, is having an effect by forcing more caution, and smaller dosages.

That optimism comes in part from this graph, from testimonies within cycling (I honestly believe that cyclists are "nervous" of the science behind the Passport), and of course, performance, which I'll end off with now.

The performance decline in the Tour, and its link to doping control and the Passport

You may also recall the great discussion we had during last year's Tour de France, where I proposed that the Tour of 2010 was one of the slowest in many years, based on power output measurements from top riders and estimates from previous years.

That all began with the hypothesis that the power output achievable without doping was limited and could be predicted based on physiology, and that any cyclist who went above this on a long finishing climb in the Tour was probably doing so with the benefit of doping!  That "limit", I suggested, was about 6.2 W/kg, a climbing power output that was very common in the 1990s and early 2000s, but which has NOT been seen since about 2006.

The graphs below show the power output in the mountains, year by year.  I haven't yet added the 2009 and 2010 figures, but it illustrates a point.  And from our analysis in 2010, the highest power output achieved on a given mountain was ± 6W/kg, while the average is in the range of 5.7 W/kg to 6 W/kg.  Much slower than preceding years.

The top graph shows average power output of the winner of the mountain stages, and the bottom shows the highest power output on a given mountain stage for the race winners.  Again, read back to our discussion of the "limit" and you'll get a picture for how the sport is slowing down.  It all builds a picture.

Wrap up

Eradicating it?  No, not at all.  And cases like those of Alberto Contador don't inspire confidence in the judicial process.  Nor do riders like Ricardo Ricco, or Patrick Sinkewitz, or any number like them.  The historical problems will not disappear overnight, particularly while many who were involved in creating the sport's doping culture either deny or continue to benefit from it.

But performance changes, and the initial results from the ABP do give cause for some optimism.  Obviously, the novel methods must be further improved - if doping control stands still, it will fall behind, because the incentive to cheat (and find new, clever ways of cheating) exists.  And you can be assured that this is happening - research to improve confidence limits, to tighten security and allow more certain limits to be set, to understand the physiology and pathology of blood values will help in future.

But for now, I hope I've given cause to suggest that the Biological Passport is not a failure by virtue of "catching" few riders.  It's strength is in its longitudinal programme, and the science, and the fact that some smart people are tightening the boundaries.

Thoughts welcome!
Ross

P.S.  As an addendum, the reference used for those ABP profiles in the post as well as the reticulocyte graph is as follows:

Implementation of the biological passport: The experience of the International Cycling Union.  Drug Testing and Analysis, (www.drugtestinganalysis.com) DOI 10.1002/dta.173.  Mario Zorzoli & Francesca Rossi.  I might add that it's a great paper to read to find out about the ABP.  It has details on how testing is done, quality-control, how many samples have been done and how they have impacted the sport.  It's likely that a lot of questions will be sent to that paper for an answer!


And once again a huge thank you to Prof Yorck Olaf Schumacher, Prof Mario Zorzoli and also to Torben Potgiesser for their input.  I don't know if any of you realized, but some of the comments in the discussion to the previous post were from them, and that is a rare privilege, to hear straight from those at the "front line" of the issue at hand.  I am especially indebted to Prof Schumacher for steering me to publications on this topic.

The Central Governor and the Athlete's Clock: Pacing and performance

Pacing, the governor and the athlete's clock: A brief interview on a fascinating concept

Jonathan came across the video below earlier today.  Now, I must confess that I had never heard of the speaker, a Dr Thomas Rowland.  Nor have I had the opportunity to read the book about which he speaks in this interview, called "The Athlete's Clock".  But the concept grabbed my attention immediately, because as you may know, this whole aspect of the brain and the regulation of exercise performance was the subject for which I obtained my PhD.

So naturally, when the very first seconds of an interview present the question "Briefly describe the Central Governor theory and where you are in adhering to it?", my curiosity is raised.  And pleasantly, I have to say that the admittedly short summary that Rowland provides about it is a pretty good version of what has been developed and proposed (by Prof Tim Noakes, and all those who have developed this theory over the last decade or so, including, in my PhD and its research, me!).

Here's the interview, with more comments below:

In a nutshell

What Rowland describes accurately is that your ability to pace yourself during exercise is the result of an "anticipatory calculation" that is made by the brain during a race/training session, and whose purpose is to prevent you from causing physiological damage to your body.

He talks about how the brain prevents you from "over-exerting" (± 40 sec in the clip) and controls the pace you can select in order to do this.  He goes on to talk about these "dangers", and mentions the examples of "breaking bones", "shredding muscles" and causing a lack of coronary blood flow to the heart, all of which are possible but never occur.

Here's where it's a little more complex than the interview allows for (understandably), and what Rowland has not mentioned is maybe the most obvious and clear-cut illustration of how pace must be regulated to protect physiology, and that is during exercise in the heat.  When we exercise in hot conditions, our pace is regulated very early on in order to reduce the rate of heat storage.  Why?  Because if we didn't slow down, we'd soon be the "victims" of a potentially harmful rise in our core temperatures.  There's quite a lot of evidence that beyond about 40 degrees celsius (maybe 41 in a highly motivated athlete), exercise is basically impossible and we lose cognitive and motor function.  Above 41 degrees, things get risky - heat stroke and the eventual risk of death are a good reason to stay below this threshold!

But happily, that rarely happens, because our brain, and this "governor", is in control and it reduces our level of muscle activation in order to prevent us from achieving these rates of heat storage and high body temperature.  Quite literally, your brain does not allow you to activate the same amount of muscle, and thus forces you to slow down.  The end result is that we slow down BEFORE becoming too hot, and not because of it. 

That this happens is intuitively obvious, but was never really allowed for in studies where athletes were made to exercise to exhaustion - that kind of model gave us the theory that we "fail" at a certain point (high temperature, in this case).  And while this is true, it is incomplete, because during self-paced exercise, which is pretty much 99% of what we do, we have this option to slow down.  How this is achieved is a fascinating physiological question.

True in every situation

The same is true in every situation - at altitude, it's not the body temperature or rate of heat storage, but the degree of oxygenation (perhaps to the brain, according to latest work) that is regulated.  In other situations, energy supply, blood glucose and glycogen levels are defended.  In others, plasma osmolality - there are innumerable different "homeostats", all of which are monitored and regulated by the brain, and then controlled by changes in exercise intensity.  And that, in a nutshell, is the Central Governor theory.

A contentious theory

Of course, no theory fits into a nutshell, and there's a lot more to it than this, including some contentious issues.  Perhaps the most common one is that the "central governor" is not a distinct location - there is no little "black box" in the brain that is doing this calculation.  It is a concept, and therefore, allows for multiple areas to regulate performance.

This too is actually obvious, because if you think about it, in order for the brain to monitor the physiological status of so many different systems must mean it is done in multiple systems or brain areas too.  So afferent (or sensory) information must be interpreted in many different areas of the brain, each with its own function (like the anterior hypothalamus for increasing temperature, for example), and these different areas all produce this conceptual response. 

There was even a time, during the period when I actually wrote my PhD thesis in 2005/6, where we tried to move away from this term "central governor", because so many people seemed to miss the point that it was not a distinct location or brain structure that had not yet been discovered.  Rather it was the function, during exercise, of existing areas, which performed the role described by Rowland in the interview above.  However, people failed to appreciate this, mostly, I suspect, because many stopped reading the early work of Prof Noakes because it "offended" their paradigm.

The result was that the theory evolved steadily, but the knowledge of what was being proposed did not, at least among those who were opposed to it.   I remember attending conferences in the USA and Europe as a young PhD student in 2004 and 2005, and feeling enormous frustration that those who argued loudest seemed often to be the ones who had stopped reading in about 1999, and were therefore pouring enormous energy into criticizing concepts that had evolved by six years while they were looking behind them.

It was as if they expected a theory to be complete in its first iteration - that version 1.0 would be the final one, no improvements allowed (of course, if this were true in other areas, can you imagine what cell phones would look like?).  Had they spent time and energy reading the latest research, I dare say many would have agreed with much of it.  This sadly will never change, but happily, new researchers are debating the issue rather than its ancestors (and their ancestors, in this case...).  Interestingly, those who argued loudest early on have still failed to acknowledge the research, but are now producing papers were they are effectively claiming "We knew the brain was involved all along" - this is typical of the evolution of knowledge.  More on this in a future post...

Conscious vs unconscious, and the rating of perceived exertion

Another fascinating area of the debate is whether this regulation is "unconscious" or not.  Do we make a conscious decision to slow down, based on cognitive processes and experience, or does the physiological process happen unconsciously, with us becoming aware of it later?  That's open to debate, but my feeling was always that it was unconscious - it had to be, because conscious motivation can be as high as you want, but if you overheat/run out of glucose/become hypoxic, you slow down. 

Also, athletes slow down with the same perception of effort, which said to me that something in the brain was upregulating their degree of discomfort even while reducing their muscle activation and pace.  If a conscious decision was responsible, you'd see a rise in RPE either before they slowed down (in which case the RPE would be the cause - a conscious model), or you would see a fall in RPE afterwards (if RPE was the effect of a conscious decision).  The fact that it is neither, I reckon, says that the RPE is part of the regulation, which is therefore unconscious.  This is somewhat philosophical, of course.

Then related to this is the issue of "failed" pacing strategies.  What happens when athletes get it wrong, and go out too hard, and do actually overheat early?  What happens in sprinters who tie up before the finish line?  I'm actually embarking on some studies to look at this question right now, using cerebral palsy as a model.

In the end, I proposed (in my PhD) a model where the subjective rating of perception of exertion (RPE) was the "integrator" of all these different physiological cues.  Your RPE is the means by which all these different brain regions integrate those multiple signals - how hot you are, how much oxygen the tissues and brain have, how much energy is available, the mechanical strain on tendons, ligaments and muscles, and so on. 

The RPE then plays the crucial "fulcrum" role, because it is generated as a result of the sensory inputs to the brain, but is also a mediator of the reduction in muscle activation and pace, specifically to make sure that the RPE does not exceed an acceptable level - after all, the reason you slowed down in your last 10km was because you felt terrible at the pace you were running!  What was happening physiologically was responsible for this, and it changed thanks to your brain slowing you down, but you didn't know that status at the time!

For those wishing to read more, I hate to reference myself, but it seems the most distinct place to start from to learn about about pacing, and these are the two reviews of the literature that arose out of the PhD:

• The physiological basis for pacing strategies during exercise:  Why we pace the way we do
• Anticipatory regulation of exercise:  The proposal of a perception-based model based on RPE

As for the book Rowland has written, "The Athlete's Clock", I can't vouch for the rest of it.  Hopefully, I will grab a copy at some stage, and then I can post properly on it!  But it's great to see a book reaching a wider audience on this topic (but then I'm biased!).  It also makes me think I should have written this book first!

Upcoming attractions

So I confess that this was supposed to a short "filler" post, just to keep the fire burning until the next big post.  I guess doing a "short filler" post on a topic as large as this, especially one to which I devoted years of research, was always impossible!  Apologies!

When that next post comes (hopefully later this week), it will be on the biological passport, which received a huge boost recently when the Court of Arbitration for Sport (CAS) ruled in favour of the passport by suspending two riders for "suspicious blood values".

The bio-passport has come under fire lately, because of what is perceived to be an inability to catch riders who cheat using all kinds of clever methods like micro-dosing and masking.  I think it's important to keep in mind that it's early days, and that researchers are slowly developing the tool.  I believe it has already had enormous positive effects on the sport, and I'll explain some of its limitations and why they don't necessarily destroy its value.

So I'll look at this in more detail, combined with some great inside information on the passport from one of its experts, and where it might be headed, as well as some of the legal issues it may face.

Also, stay tuned for some exciting news from Jonathan's life, and what it may mean for us here at The Science of Sport!

Until then, pace yourselves!
Ross

The limit of human performance: How much faster?

Swifter, higher, stronger...up to a point?  Or beyond?  The limit of human performance

Today we revisit a topic that seems to run like carousel, popping up once every few months on the site - how much faster can human beings run?  How close to a "ceiling" in performance are we?

The latest discussion is inspired by a few articles, and a recent round-table discussion between some of the all-time greats of 800m running, and the new world record holder, David Rudisha.  For those who haven't heard, Rudisha was appropriately named the IAAF Male Athlete of the Year for his two world records in 2010.

But preceding that announcement was a panel discussion between Alberto Juantorena, Sebastian Coe, Wilson Kipketer And Rudisha in Monaco.  To watch the discussion and read some commentary on it, check out Letsrun.com here.

One of the topics that came up was how much faster the record would still go.  Rudisha came agonizingly close (1/100th of a second) to dipping under 1:41.00, so it's safe to assume that barrier is in reach.  But how much lower?  Here are three quotes attributed to those legends:

"This record belongs to the future - 1:41.01." and "You never know the limit of a human being." - Alberto Juantorena

"I don't think we're anywhere near them (the limits of the event) ..." - Seb Coe

"In 800 it is possible to run under 1:40. It is still coming." - Wilson Kipketer

Then, an interesting piece by the Guardian discussed the same issues around whether we are near the limits, with the conclusion that it will take many years before we know the answer to this question.  I will point out that saying this is not quite the same thing as saying that we are not near the limit, but rather that we just do not know where it is.  There is a ceiling somewhere above us, but we don't know when we will hit our head!  You can read that piece here.

The physiological basis for "limits"

In trying to evaluate these arguments, I think it's important to understand a little bit about the physiological basis for why there may be a limit to performance.  And here, the most important thing to recognize is that we don't fully know what that basis might be.  It certainly varies by event, and is more complex than I want to go into now, but those keen for more might consider reading our series on Fatigue and Performance

For example, in 100m sprinting, some limits are the metabolic changes in the muscle, which affect its force-producing capacity, combined with mechanical factors such as muscle-tendon elasticity, ability to apply force to the ground, the force and torque on joints, and limits to how quickly neural signals can reach the muscle from the brain.

Some really interesting work by a colleague at my university has confirmed that the rate of force production and muscle relaxation drops over time during maximal exercise, even when the electrical signal to activate the muscle doesn't change.  In other words, there is a drop in the force that the muscle can produce, and that's why even events as short as 10 seconds show signs of pacing - if you go too hard early, you fall away at the end.  But, the peripheral factors, like acidosis in the muscle, depletion of ATP, accumulation of calcium and phosphate are only part of the problem, and the Guardian article talks more of the mechanics of sprinting, which affect the force production on the ground.

As you move up in distance, other factors play more of a role.  The rate of energy supply becomes a factor in middle-distance events, oxygen availability is a potential limiter (though whether it is to skeletel muscle or to the brain (more likely) is a debate).  So too, chemical changes such as a drop in pH may be regulated or responsible for a decline in performance.  Then, as you reach marathon distances, fuel availability becomes important (hitting the wall being the obvious sign of not getting this right), and the ability to burn fat to preserve glycogen is part of the elite athlete make-up.  Heat storage is another limiting factor, because fatigue occurs when the body temperature reaches what has been called a critical level of hyperthermia.

The point is that performances are not limited by one thing only, but rather a complex interaction between all the physiological systems, whose weighting depends on the type of event, and the external conditions for the event on the day.

Those interested in a more academic discussion of the topic might consider the following review articles:

Distribution of cycling power output: Impact and mechanisms

Physiological regulation of pacing strategies (and hence exercise performance)

Model for performance regulation by the brain

Applying this to performance limits

In any event, you may be wondering what this has to with a debate over whether an athlete can run under 1:40 for 800m, sub 9.40s for 100m, or break the 2-hour barrier in the marathon?

Well, in my view, knowing that performance is limited by physiological changes in the muscle, lungs, heart, brain, body temperature, there is an obvious "barrier" that cannot be broken without causing harm to the athlete.  We cannot simply head out and run or cycle ourselves to the limit - our brain controls the degree of muscle activation so that we are protected against, quite literally, exercising ourselves to death.  So the brain will, for example, detect the rate of heat storage early on and then reduce the exercise workrate through adjustments in muscle activation, the result of which is a slowing in pace, but also a drop in heat storage and avoidance of that limiting body temperature.  The same presumably happens with oxygen availability, glucose supply (probably both to the brain), blood flow, cardiac output, osmolality - any number of "homeostats" that have to be defended in order for us to survive

This is the reason, incidentally, that it is possible to predict the maximal sustainable power output by a cyclist during a mountain climb in the Tour de France.  We did this in July during the Tour, to some criticism, but I'm confident in saying that the physiological basis is sound, and so too is the prediction that power outputs of 6.1 W/kg to 6.3 W/kg represent a maximal power output that is possible given human physiology.

In other words, exercise performance is limited by a capacity in oxygen delivery, a capacity in heat storage and body temperature, a capacity in the rate of ATP supply, a capacity in the total energy availability.  Short of finding a human being who exceeds everything we know of physiology, or finding that individual who possesses the maximal combination of every single physiological attribute (this individual doesn't exist except in theory), the records will not "leap" forward, they will inch forward incrementally, and I do believe that we are quite close to the limit, when world records will become more and more infrequent, and eventually no longer be broken, unless we start measuring down to the nearest thousandth of a second.

The sub-2 hour marathon as an example

Let's look at the sub-2 hour marathon as an example.  This came up last week again, when Ed Coyle suggested that he was "confident" it could happen and predicted a 1:58 as the limit.  It won't be in my lifetime, that's for sure, but I'll get onto that shortly.

The 1:58 prediction, incidentally, is based around this paper, which applied much the same process as we did to cycling in the Tour to suggest the 6.2W/kg limit.  It works on the premise that performance in the marathon is limited (I would rather say regulated, but that's debated in our fatigue series) by oxygen delivery, lactate threshold and running economy.  It concludes that 1:57:58 is possible for "a hypothetical subject with a VO2max of 84 ml/kg/min, a lactate threshold of 85% of VO2max, and exceptional running economy".

The word "hypothetical" is important, because performance is not hypothetical.  That study was done in 1991, and knowledge of the limiting factors has evolved a little.  The role of the brain has become recognized, as have the mechanical factors such as energy storage and return in the tendons.  The key for me is that the athlete with a VO2max that high never has an exceptional running economy, so it is much like trying to find a motor vehicle with a 6 liter engine that also gets you 80 miles to the gallon (and those are the kind of unrealistic figures we're talking in combination) 

Another key point is that performance is determined by more than just the VO2 max and lactate threshold.  Athletes regularly "under-perform" given their physiological stats - perhaps it is because they lack racing nous or desire, they don't have the discipline to train, they are too big and thus heat storage becomes a factor for them.  Perhaps they are injury prone and so despite having the highest VO2max and economy in the history of sports science, they can't run 40km a week before breaking down.  The point is that for this "hypothetical athlete" to have a shot at a sub-2 hour marathon, there have to be hundreds of them, because the set of characteristics needed is not limited to three, and is extremely rare.

However, I would be surprised if there was even one such athlete,  let alone hundreds, because he would have been found by now.  An arguable point, certainly, but I believe that kind of physiology to be so rare that this person would stand out instantly and therefore, given the "free-market" that is sport, they would have been seen already. 

The performance spectrum - why one performance doesn't exist in isolation

The other reason the sub-2 hour marathon is, in my opinion, unlikely, is because it has implications for what happens at shorter distances.  I've described this before and would encourage you to read this post if you're interested, but the summary of it is that in order for a marathon to be run in under 2 hours, that athlete must possess a half marathon that lies closer to 57 minutes, and more tellingly, a 10,000m in closer to 25 minutes.  This once again comes back to the issue that all performances in these complementary events are limited by similar physiological "regulators", so that the physiology of a great 10,000m runners is often easily transferred up to the marathon (Haile Gebrselassie, Paul Tergat and Sammy Wanjiru are exhibits A, B and C).

So don't ask whether a sub 2 hour marathon is possible, rather ask whether a 25-xx minute 10km is possible.  Improvements in the 10,000m world record have declined in recent years, to the point that even a sub-26 minute time seems unlikely for a long, long time.  Therefore, even though mathematical predictions for the marathon have suggested that if performance continues to improve at the same rate, we'll see the 2 hour marathon in 2021, it seems unlikely given how improvements in the 10,000m event have dropped off recently.

Also, there are less "scientific" reasons why it will take much longer than predicted, and one is the lack of courses where a 2:03 time is possible, combined with commercial interests.  Right now, only Dubai, Berlin and possibly Chicago have the kind of course and money to drive a world record attempt.  Then it requires perfect conditions - 1 or 2 degrees too hot, a slight headwind, too cold, wet, and the record possibility disappears.  So unlike Ed Coyle, I'm not at all "confident" we'll see a sub-2 hour marathon.  Certainly not in our life-times, if at all.

The sub-4 minute mile response

So the question that comes up many times in response to this kind of opinion is that back in 1953, people suggested that the mile world record was at its limit and that the 4-minute mile would not be broken.  History clearly proves that to have been foolish, as the record is now 17 seconds faster, and many high-school athletes are breaking the barrier.  So therefore, is there not a chance that the same applies to the 2-hour marathon?

Of course there is.  But, there are some fundamental differences between that situation and the current one.  What we know of physiology now says that the 4- minute mile was always going to happen.  So if in 50 years, athletes are running under 2-hours in the marathon, then it will be because we have missed something in our understanding of the physiology today.  What are the chance of that?  Pretty high, of course, it would be arrogant to say that we know everything, we simply cannot.

However, I don't believe there are fundamental physiological principles that have not yet been discovered.  Performance is limited by the physiological regulators, and things like VO2max, running economy, threshhold running pace and thermoregulation are known to be regulators.  So we're either wrong, or we're still waiting for that one-of-a-kind human being who possesses physiological stats never seen before.  That wasn't the case in the 1950s - they were good athletes with exceptional but expected physiology, and it was lack of professionalism and training/diet, along with "vision" of what might be possible that limited them

Today, with money to be made, advancements in training, globalization of the sport (back then, Kenyans may have been running 3:50 for the mile, who knows?  They weren't competing enough), and a shifting of the horizon in terms of limits, we know much more what is possible.  We know what kind of physiological specimens exist, and I believe, we know what doesn't exist.  Genetic engineering may change that, but I really do believe we're approaching those limits.

In the 100m, Bolt came along and blew away the record books, but he hasn't done anything that mathematical models suggested would be impossible - they have the record limit at 9.48s, based on hundreds of years of data.  He just took us closer to it long before anyone thought it might happen.

Similarly, in the 800m, Rudisha has edged us towards 1:40 (only by 1/10th of a second, compared to Kipketer), and it does seem possible that this record will be improved again.  In the marathon, we have to find four minutes, from the same populations we're working with now, with limited opportunities for the record to be broken.  Physiologically, hypothetically, 1:58 is possible, but I don't share the confidence, and I don't believe that the hypothetical athlete exists, and I'd be very surprised if the record dips below 2:03 in the next fifteen years, and perhaps then we'll have a better idea of where the ceiling is, if we haven't hit our heads against it by then!

Ross

More detailed reading for those interested:


The Sub-2 hour marathon:  The link between 10,000m times and marathon times, and why it'll take longer than expected to crack 2 hours


The physiology of a sub-2 hour marathon runner

Cycling performance: What is possible?

The limit to cycling performance: Can physiology flag doping?

Yesterday I posted on the upcoming Tour de France, and made mention of a topic that I feel is:
a) Really interesting as a means to add value to watching the sport, and
b) Potentially interesting as a means to flag suspicious performances.

And rather than wait until the Tour begins, I thought I'd take advantage of a rest day in the FIFA World Cup to get some thoughts going, since I left yesterday hanging somewhat (deliberately, but still...)

And so here are some thoughts on the ability of performance to predict physiology.

Estimation and assumption

Perhaps right up front, I have to talk briefly about estimation and assumption vs measurement.  Of course, the ideal would be to get accurate SRM data on the power output on the climbs.  Of course, it would be wonderful to know with precision what the power output was, but as I hope to illustrate, the errors in these kinds of calculations can both be minimized and controlled so that you end up with a 'best case scenario".

This is much the same situation you would find yourself in if, for example, you wanted to open a coffee shop and had to do prepare a business model.  You don't know how many cups of coffee you'll sell, you don't know how many biscuits to bake.  But if you know your market, and its people (your future customers, you hope), then you can control your assumptions and go a long way to making a conclusion.  That is, if you make "best-case" assumptions and still your coffee shop is running at a loss, then it clearly is not a viable business.  If your "worst-case scenario" (few customers, few sales) still makes a profit, then the business works.  Realistic and sensible assumptions are the key to ensuring that your conclusion is accurate, even in the absence of a crystal ball!  Similarly, for these physiological calculations, you can make "best-case" assumptions and if the picture still doesn't fit, then you have a good case for a problem.

So over the next few weeks, I think we must acknowledge right away that these are always estimations - of power output, of body mass, of bike mass, of wind speeds and directions - all these factors will affect the eventual physiological calculation, but for two reasons, their effect is not as large as you might think:

1. We're not proving anything here - only suggesting physiology for the purposes of increasing enjoyment and stimulating discussion, and 
2. The physiological implications are so large that even errors don't affect the conclusion.

So let's say it now, one last time - this is not proof, but an interesting exercise nonetheless, and I believe a compelling way to approach the problem.  Ultimately, people will believe what they wish to, even when presented with a 'creaking and ugly edifice'.

So let's get cracking...

An extreme case - the physiological implications of 8 W/kg for 40 minutes

Let's take a rider who produces 8 W/kg.  Assume his mass is 70kg, which means an absolute power output of 560W.  Clearly, very high.

In order to work out the physiological implication, by which I mean the oxygen cost, there are two potential methods.

The first involves the use of a published paper called "Peak power output predicts maximal oxygen uptake and performance time in trained cyclists".  This study looked at 100 trained cyclists and established the following relationship between oxygen consumption (VO2) and power output.  The relationship is:

VO2 (L/min) = (0.01141 x Power output) + 0.435

Therefore, if you take the power output of 560W, and you apply this equation, you will calculate an oxygen consumption of 6.82 L/min.  Relative to body mass, this is equal to 97.49 ml/kg/min.

The second method, just for comparison's sake, requires that you do three things:

1. You calculate the real energy cost of producing that power, by taking advantage of the fact that cyclists are not perfectly efficient.  In fact, elite cyclists are only about 23% efficient.  What this means is that a cyclist who is riding at 560W is in fact producing 2435 W.  Clearly, we now have our first assumption - the efficiency.  Lance Armstrong's efficiency was measured as 23.12%.  Other studies find values that range between 21% and 27%, though values over 25% are hotly debated, and basically dismissed as an artefact of testing and equipment.  This is a controversial issue, but most elite cyclists seem to be around this 23% value, and since Armstrong's was measured there, I'll use it for the remainder of this calculation.
   
   
2. The total energy can now be used to work out an oxygen consumption.  This requires that you have knowledge of the contribution of various energy stores to the physiology.  We know that every liter of oxygen used produces between 4.69 kCal and 5.05 kCal, depending on whether fat is being used, or carbohydrates.  So, this is our next assumption - which end of this spectrum do we use, the 4.69 or the 5.05kCal?  The answer is the further right extreme, for two reasons.  One is that it's physiologically reasonable - a cyclist producing maximum effort is going to be near maximally using carbohydrates.  Second, this is the "conservative" or "best-case" assumption, as explained earlier.  So we'll run with 5.05 kCal/L O2.
   
   
3. We can now work out the oxygen consumption for a given power output at a given efficiency.

In our example, 560 W produces an oxygen consumption of 6.91 L/min, or 98.71 ml/kg/min.

You'll note that this is similar to the value of 97.91 ml/kg/min that we calculated using Method 1.  This suggests that the above assumptions of efficiency 23% and energy use per liter of oxygen are correct.  I must point out that we haven't yet considered the contribution of non-oxygen dependent pathways (the so-called anaerobic contribution) to energy.  This is of course important, but I would also point out that we are talking about a cyclist who is producing this power output for 40 minutes at the end of a 5-hour cycling day, and so the assumption on energy demand, given the length of exercise, is still valid (in my opinion).

Now, what do you make of that oxygen consumption of 97.9 ml/kg/min?  If I measured it in the lab, I'd be checking my equipment...clearly, something is wrong.  And if a cyclist were able to produce that power output (8 W/kg) for 40 minutes, with that physiological implication, then you'd be calling him out (or you'd be looking for the electric motor in his pedals).

If you assume, for example, that a cyclist can maintain 90% of their maximal level for 40 minutes, then this oxygen use of 97.9 ml/kg/min corresponds to a VO2max of 110 ml/kg/min.  The red flag is clearly waving.

So when is it possible for a cyclist to ride at 8W/kg, assuming they have a VO2max of 80 ml/kg/min?  Well, their cycling efficiency would have to be around 32% - many percent higher than anything ever measured before.  9 W/kg, which I throw out only because it was suggested is possible on a chat forum, would require that a cyclist with a VO2max of 80 ml/kg/min is 35% efficient.  Either that, or a cyclist with an efficiency of 23% would have to have a VO2max of 123 ml/kg/min.  It simply doesn't happen, and therefore, neither do 8W or 9W/kg for 40 minutes.

Now, let's look at a much more conservative assumption - the decent level cyclist...

The "low end" - 4 W/kg for 40 minutes

Most trained cyclists would be able to produce this power output.  In our lab, we test the range of beginners to elites, and this what you would expect of a decent level cyclist.  And we know that a decent cyclist will produce a VO2max of around 60 ml/kg/min.

Using the same method as before, we can estimate that the oxygen consumption associated with this performance of 280 W is equal to 51.9 ml/kg/min.  If you prefer method 2, using an efficiency of 23%, then you'll calculate 49.4 ml/kg/min.  The reason this is lower, incidentally, is because this person is unlikely to have an efficiency of 23%, but one that is lower than this.  If we use 22%, for example, we calculate 51.6 ml/kg/min.  Again, this shows that 23% is a pretty safe "best case" estimation.

Again, if you assume that a rider such as this is maintaining 90% of max, then the inferred VO2max would be equal to 57.6 ml/kg/min.  That's a perfectly reasonable value.  If anything, it's on the low side, which I again point out shows that the assumptions I'm making for all these calculations are "conservative".

The key assumption in this regard is the 90% of maximum assumption.  In reality, a good level cyclist will ride at 85% of maximum, which means our inferred VO2max suddenly rises to 61 ml/kg/min.  I also maintain that a Tour rider, on the final climb of the day, will be closer to 85% than 90%, given that they've been riding for five hours.  However, this assumption is debatable.  My point is, if the physiology is still unrealistic with these safe assumptions, then you know you have a problem.

So now, we've looked at two extremes - the high, which simply doesn't exist, and the low, which is safe and clear and maybe even a little conservative.  There is a point in between, where elite Tour riders exist, where the really interesting questions begin.  So let's look at a Tour rider...

Bjarne Riis - 6.8 W/kg for 35 min on Hautacam.  Or Armstrong - 6.6 W/kg for 38 min on Alp d'Huez

Bjarne Riis is estimated to have produced 6.8W/kg (480W) on Hautacam when he won the Tour in 1996.  Armstrong's estimated power output on Alp d'Huez was 6.6 W/kg (465W).  This is Vayer and Portoleau's estimation, and I believe it to be accurate.  I actually saw a PhD student from Texas present a similar analysis at the ACSM conference in 2005, and he had worked out 495W (7 W/kg), taking into account the gradient every 100m as well as wind speeds.  If anything this is more accurate.  But as I mentioned, we'll be "conservative" in our calculations, so let's take the lower option and see what it means, physiologically.

We again assume 23% efficiency (in Armstrong's case, this is not an assumption - it was measured by Coyle), and we can calculate that the oxygen cost of producing 465 W is equal to 81.96 ml/kg/min.  Using method 1, the equation from the published literature, we find oxygen use of 82.00 ml/kg/min, pretty much identical.

Now, is it possible to ride at 81.96 ml/kg/min for almost 40 minutes?  If you are at 90% of maximum, then it means that the VO2max must be equal to 91.07 ml/kg/min.  If you are at 85% of maximum, then the maximum must be 96.42 ml/kg/min.  Given that by the time these performances happen, the cyclist has been in the saddle for five hours, not to mention about 2 weeks before, I feel pretty safe in saying that you're projecting a VO2max that lies somewhere between 91 and 96 ml/kg/min, probably closer to 96 ml/kg/min.

Another example comes from Armstrong's own words.  In this interview, he says "I also cranked out 495 watts for more than 30 minutes".  495 W is about 7W/kg, and applying the same equations as I've done throughout this post, you can work out that it requires oxygen consumption of 87 ml/kg/min, and a VO2max of 97 ml/kg/min (and that's at 90% of maximum.  If you go with 85%, you get 103 ml/kg/min...).  

Is that realistic?  I suspect that your answer to that question depends not on what you know, but rather on what you want to believe.  I don't believe that it is possible, because the combination of high efficiency (and 23% is high) and high VO2max doesn't seem to exist.  In fact, Lucia et al showed that there was an inverse relationship, so that those with the best efficiency had the lowest VO2max. So the problem is that if you suggest that we increase the efficiency to make the predicted VO2max come down, you're chasing the pot of gold at the end of the rainbow, because the possible VO2max is coming down anyway!

However, people will draw their own conclusions.  I am of the opinion, like Prof Aldo Sassi, that a value above 6.2 W/kg is indicative of doping.  And in the coming weeks, I will post more on this, including graphs that hopefully illustrate this point even more clearly.  But, as always, there is likely to be debate.

Next up - the Quarterfinals

That's it for cycling for now - during the course of the Tour de France, we'll return to this kind of approach and look at some of the performances, and compare them to historical numbers.  As always, the discussion is welcome.

The cycling now gets put on hold for a few days while the Football World Cup Quarter Finals take place!  I am sitting on piles and piles of data about how far players run at different altitudes, and even how goalscoring seems to be affected by the altitude.  But perhaps for two days, I will be a fan, and then resume the analysis next week!

Oh, and there's Wimbledon!  And the start of the Tour!  Enjoy it, and we'll be back soon!

Ross