Could we have evolved traits that are detrimental to our survival?

Let us assume that we collected data on the presence or absence of a trait (e.g., propensity toward risky behavior) in a population of individuals, as well as on intermediate effects of the trait, downstream effects on mating and survival success, and ultimately on reproductive success (a.k.a. “fitness”, in evolutionary biology).

The data would have been collected over several generations. Let us also assume that we conducted a multivariate analysis on this data, of the same type as the analyses employing WarpPLS that were discussed here in previous posts (). The results are summarized through the graph below.



Each of the numbers next to the arrows in the graph below represents the strength of a cause-effect relationship. The number .244 linking “a” and “y” means that a one standard deviation variation in “a” causes a .244 standard deviation increase in “y”. It also means that a one standard deviation variation in “a” causes a 24.4 percent increase in “y” considering the average “y” as the baseline.

This type of mathematical view of evolution may look simplistic. This is an illusion. It is very general, and encompasses evolution in all living organisms, including humans. It also applies to theoretical organisms where multiple (e.g., 5, 6 etc.) sexes could exist. It even applies to non-biological organisms, as long as these organisms replicate - e.g., replicating robots.

So the trait measured by “a” has a positive effect on the intermediate effect “y”. This variable, “y” in turn has a negative effect on survival success (“s”), and a strong one at that: -.518. Examples: “a” = propensity toward risky behavior, measured as 0 (low) and 1 (high); and “y” = hunting success, measured in the same way. (That is, “a” and “y” are correlated, but “a”=1 does not always mean “y”=1.) Here the trait “a” has a negative effect on survival via its intermediate effect on “y”. If I calculate the total effect of “a” on “w” via the 9 paths that connect these two variables, I will find that it is .161.

The total effect on reproductive success is positive, which means that the trait will tend to spread in the population. In other words, the trait will evolve in the population, even though it has a negative effect on survival. This type of trait is what has been referred to as a “costly” trait ().

Say what? Do you mean to say that we have evolved traits that are unhealthy for us? Yes, I mean exactly that. Is this a “death to paleo” post? No, it is not. I discussed this topic here before, several years ago (). But the existence of costly traits is one of the main reasons why I don’t think that mimicking our evolutionary past is necessarily healthy. For example, many of our male ancestors were warriors, and they died early because of that.

What type of trait will present this evolutionary pattern – i.e., be a costly trait? One answer is: a trait that is found to be attractive by members of the other sex, and that is not very healthy. For example, a behavior that is perceived as “sexy”, but that is also associated with increased mortality. This would likely be a behavior prominently displayed by males, since in most species, including humans, sexual selection pressure is much more strongly applied by females than by males.

Examples would be aggressiveness and propensity toward risky behavior, especially in high-stress situations such as hunting and intergroup conflict (e.g., a war between two tribes) where being aggressive is likely to benefit an individual’s group. In warrior societies, both aggressiveness and propensity toward risky behavior are associated with higher social status and a greater ability to procure mates. These traits are usually seen as male traits in these societies.

Here is something interesting. Judging from our knowledge of various warrior societies, including American plains Indians societies, the main currency of warrior societies were counts of risky acts, not battle effectiveness. Slapping a fierce enemy warrior on the face and living to tell the story would be more valuable, in terms of “counting coup”, than killing a few inexperienced enemy warriors in an ambush.

Greater propensity toward risky behavior among men is widespread and well documented, and is very likely the result of evolutionary forces, operating on costly traits. Genetic traits evolved primarily by pressure on one sex are often present in the other (e.g., men have nipples). There are different grades of risky behavior today. At the high end of the scale would be things that can kill suddenly like race car driving and free solo climbing (, ). (If you'd like to know the source of the awesome background song of the second video linked, here it is: Radical Face's "Welcome Home".)

One interesting link between risky behavior and diet refers to the consumption of omega-6 and omega-3 fats. Risky behavior may be connected with aggressive behavior, which may in turn be encouraged by greater consumption of foods rich in omega-6 fats and avoidance of foods rich in omega-3 fats (, ). This may be behind our apparent preference for foods rich in omega-6 fats, even though tipping the balance toward more foods rich in omega-3 fats would be beneficial for survival. We would be "calmer" though - not a high priority among most men, particularly young men.

This evolved preference may also be behind the appeal of industrial foods that are very rich in omega-6 fats. These foods seem to be particularly bad for us in the long term. But when the sources of omega-6 fats are unprocessed foods, the negative effects seem to become "invisible" to statistical tests.

We share an ancestor who probably lived no more than 640 years ago

This post is a revised version of a previous post. The original post has been or will be deleted, with the comments preserved. Typically this is done with posts that attract many visits at the time they are published, and whose topics become particularly relevant or need to be re-addressed at a later date.

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We all evolved from one single-celled organism that lived billions of years ago. I don’t see why this is so hard for some people to believe, given that all of us also developed from a single fertilized cell in just 9 months.

However, our most recent common ancestor is not that first single-celled organism, nor is it the first Homo sapiens, or even the first Cro-Magnon.

The majority of the people who read this blog probably share a common ancestor who lived no more than 640 years ago. Genealogical records often reveal interesting connections - the figure below has been cropped from a larger one from Pinterest.

You and I, whoever you are, have each two parents. Each of our parents have (or had) two parents, who themselves had two parents. And so on.

If we keep going back in time, and assume that you and I do not share a common ancestor, there will be a point where the theoretical world population would have to be impossibly large.

Assuming a new generation coming up every 20 years, and going backwards in time, we get a theoretical population chart like the one below. The theoretical population grows in an exponential, or geometric, fashion.

As we move back in time the bars go up in size. Beyond a certain point their sizes go up so fast that you have to segment the chart. Otherwise the bars on the left side of the chart disappear in comparison to the ones on the right side (as several did on the chart above). Below is the section of the chart going back to the year 1371.

The year 1371 is a mere 640 years ago. And what is the theoretical population in that year if we assume that you and I have no common ancestors? The answer is: more than 8.5 billion people. We know that is not true.

Admittedly this is a somewhat simplistic view of this phenomenon, used here primarily to make a point. For example, it is possible that a population of humans became isolated 15 thousand years ago, remained isolated to the present day, and that one of their descendants just happened to be around reading this blog today.

Perhaps the most widely cited article discussing this idea is this one by Joseph T. Chang, published in the journal Advances in Applied Probability. For a more accessible introduction to the idea, see this article by Joe Kissell.

Estimates vary based on the portion of the population considered. There are also assumptions that have to be made based on migration and mating patterns, as well as the time for each generation to emerge and the stability of that number over time.

Still, most people alive today share a common ancestor who lived a lot more recently than they think. In most cases that common ancestor probably lived less than 640 years ago.

And who was that common ancestor? That person was probably a man who, due to a high perceived social status, had many consorts, who gave birth to many children. Someone like Genghis Khan.

Bolt vs Farah at 600m. The extremes meet, who wins?

Bolt vs Farah over 600m: The extremes meet in the middle (kind of, physiologically...)

For athletics fans, the prospect of Usain Bolt vs Mo Farah over 600m offers an enthralling spectacle where the most dominant athletes at the extremes of track running test themselves with one foot in the other’s domain.  I suspect it is highly unlikely to happen, but it's a great platform for some debate around performance physiology.

Predicting the winner is a fun exercise in stats, performance analysis and physiology (performance analysis - it's not an exact science, remember!).  

The fascinating question for this one is where do the physiologies of these two “extreme” athletes cross?  Of course, bear in mind that there are athletes in the middle who would arguably beat both Farah and Bolt over 600m, and by a long way.  When David Rudisha broke the 800m WR in London last year, his 600m split time was 1:14.3, and that's about as fast as I suspect Farah or Bolt could run in a straight 600m.  

Rudisha's 1:40.91 predicts something under 1:12 for 600m (the world record is 1:12.81, and that's from Johnny Gray, who was 1.6 seconds slower than Rudisha at his best), so he would certainly win a 600m were he in it.  In fact, so would just about the entire men's 800m Olympic final field, and a good few 400m, 400m hurdlers and 1500m runners (the 800m/1500m combo guys) too - this 600m is not about finding the best athlete, but about some fun and publicity!

Physiology at the 'extremes'

Physiologically, making the prediction invites some discussion over the origin and capacity of the energy pathways used by each, and what it means for fatigue. 

It boils down to different questions for each man.  For Bolt, it’s whether he can withstand the fatigue of going three times further than his normal race distance, and how much he would need to slow down to avoid complete failure to even finish the distance?

For Farah, it’s whether his top speed is high enough to pressurize Bolt into that premature fatigue? 

A quick physiological lesson will explain:  When you see athletes tying up and slowing down dramatically at the end of a sprint race, what you are witnessing is the combination of a "failure" of energy production (the supply can't meet the demand), a build up of metabolic by-products in the muscle and the central and peripheral responses to these changes.  Nobody knows the full explanation for this, and it’s likely more complex than any current theory can explain, but the result is a reduction in muscle contractility with sub-maximal muscle recruitment.  

Studies have shown, for instance, that at the end of a 400m race, drop-jump performance declines by 39% and that muscle activation increases, which shows the cumulative effects of fatigue on muscle function - more recruitment needed for less force/power.  Other studies show that this happens despite pacing, and the presence of some muscle unit reserve, which implies that fatigue occurs partly in the brain, partly in the muscle.

The source of energy is crucial to both fatigue processes, because it affects the biochemical changes occurring in the muscle.  Bolt and Farah rely on different pathways for their energy.  Bolt has a highly developed pathway that produces the energy needed for muscle contraction very rapidly, but not for very long.  His energy comes primarily from what are known as oxygen independent (or anaerobic, though this word is avoided by many) pathways.  They are all about the speed of energy supply, and the consequence – a build up of metabolites, is an accepted downside because he doesn’t need more than 20 seconds of explosive power. 

Farah, on the other hand, can produce energy for hours, but more slowly, using primarily oxygen dependent, or aerobic pathways.  The upside is less peripheral accumulation (though glycogen depletion is, eventually, a theoretical 'limit'), the downside is the rate of supply.  This difference accounts for the clear differences in the optimal pacing strategy between short duration and long-duration events, something I summarized in this review article for BJSM.

There is always an overlap, with some contribution from both pathways, no matter the distance, but for shorter, high intensity exercise like sprinting, the oxygen-independent pathways are more heavily relied upon (in the 200m event, for instance, the split is around 70%-30% in favor of energy production without oxygen.  By 1500m, it is reversed to 30%-70%). 

So, as much as Bolt and Farah lie at the opposite ends of the performance spectrum, they are also extremes of biochemistry.  Muscle histology and function also differ – Bolt’s are more contractile, able to contract rapidly and forcefully, but they also fatigue more rapidly.  

The prediction

Over the nominated distance of 600m, Farah would be forced to find a force and speed of muscle contraction and energy production that he is unfamiliar with, while Bolt will be asking his biochemistry to withstand an accumulation of metabolites and resultant fatigue that he is also unaccustomed to.

As for a prediction, the biochemical odds are slightly tilted in Farah’s favor at 600m.  A number of people have attempted to model where the perfect distance is, and using the above-mentioned energy pathway models, have estimated that the perfect distance, with equal performances, lies somewhere between 500m and 550m.   

Those additional 50m, seemingly trivial, probably just give Farah the edge and represent 50m too far for Bolt’s physiology.  Farah’s famous finishing kick, as well as his recent 1500m performance, a European record of 3:28, have shown that he has extra-ordinary sustained speed for a distance runner, so the biochemical “jump” to a 600m may not be as large as the step up from 200m to 600m for Bolt. 

On that performance note, Farah's 600m performance is easier to predict and is more familiar to him - it's something he'd do regularly in training, whereas Bolt would very rarely approach even sub-maximal efforts for this duration.  

Performance-wise, Farah's 3:28 suggests that his 800m performance would be in the range of 1:45 to 1:46.  That would optimally be achieved with a 51-52s first lap, and a 53-54s second lap.  That in turn suggests that a very fast 400m of 49s would be possible.  Then it becomes a question of limiting the slow down, and finishing with a time around 1:14-1:15.  It's about starting fast enough to take advantage of sustainable speed and attenuated slowing down at the end.

Bolt, on the other hand, has to worry about the opposite problem - not starting too fast.  He has run 400m in under 46s almost every year since 2007, including a PB of 45.28s six years ago, and a 45.35s at the age of only 17.  So he may have the natural ability, if he judges the pace well, to edge Farah.  However, six years is a long time, and those low 45s are probably less relevant now, particularly since he has probably gained mass since 2007.  Mass hurts over longer distances, so Bolt has this to deal with as well.  If Bolt does go out in 48s, gaining an advantage of around a second over Farah, he'd need to hold on to around 27s for the final 200m, and I suspect that would be a little too much to ask.

With a month of dedicated training for the 600m distance, my money would be split.  In my opinion, it would be a coin toss - Bolt would be able to change the training enough to adapt just enough to make it incredibly close.  But, if the race were to happen straight after their specialized seasons, Farah has the edge.  I'd pick Farah by about half a second to a second.  Over 550m, maybe it comes down to the lean.  It would be a fascinating meeting of two extremes.  It would sure be fun to watch, and discuss - that happens over on Twitter and Facebook!

Ross

Could grain-fed beef liver be particularly nutritious?

There is a pervasive belief today that grain-fed beef is unhealthy, a belief that I addressed before in this blog () and that I think is exaggerated. This general belief seems to also apply to a related meat, one that is widely acknowledged as a major micronutrient “powerhouse”, namely grain-fed beef liver.

Regarding grain-fed beef liver, the idea is that cattle that are grain-fed tend to develop a mild form of fatty liver disease. This I am inclined to agree with.

However, I am not convinced that this is such a bad thing for those who eat grain-fed beef liver.

In most animals, including Homo sapiens, fatty liver disease seems to be associated with extra load being put on the liver. Possible reasons for this are accelerated growth, abnormally high levels of body fat, and ingestion of toxins beyond a certain hormetic threshold (e.g., alcohol).

In these cases, what would one expect to see as a body response? The extra load is associated with high oxidative stress and rate of metabolic work. In response, the body should shuttle more antioxidants and metabolism catalysts to the organ being overloaded. Fat-soluble vitamins can act as antioxidants and catalysts in various metabolic processes, among other important functions. They require fat to be stored, and can then be released over time, which is a major advantage over water-soluble vitamins; fat-soluble vitamins are longer-acting.

So you would expect an overloaded liver to have more fat in it, and also a greater concentration of fat-soluble vitamins. This would include vitamin A, which would give the liver an unnatural color, toward the orange-yellow range of the spectrum.

Grain-fed beef liver, like the muscle meat of grain-fed cattle, tends to have more fat than that of grass-fed animals. One function of this extra fat could be to store fat-soluble vitamins. This extra fat appears to have a higher omega-6 fat content as well. Still, beef liver is a fairly lean meat; with about 5 g of fat per 100 g of weight, and only 20 mg or so of omega-6 fat. Clearly consumption of beef liver in moderation is unlikely to lead to a significant increase in omega-6 fat content in one’s diet (). By consumption in moderation I mean approximately once a week.

The photo below, from Wikipedia, is of a dish prepared with foie gras. That is essentially the liver of a duck or goose that has been fattened through force-feeding, until the animal develops fatty liver disease. This “diseased” liver is particularly rich in fat-soluble vitamins; e.g., it is the best known source of the all-important vitamin K2.



Could the same happen, although to a lesser extent, with grain-fed beef liver? I don’t think it is unreasonable to speculate that it could.

Alan Oliveira runs 10.57s. Leg length or something else? Over to the IPC and IAAF

Alan Oliveira runs 10.57s: Is it leg length, or something else? Over to the IPC/IAAF

Hot on the heels of a 20.66s World Record for double-amputees in Lyon a week ago, Alan Oliveira of Brazil, the fastest double amputee in the world, today destroyed his own 100m World Record with a performance of 10.57s in the London Olympic stadium.

I wrote about his emergence as the heir to Oscar Pistorius last week, describing the implications of his incredible improvements in 2013.  He last week won the 100m, 200m and 400m titles in the IPC World Championships, and is now a staggering 0.44s faster than the next fastest in history at 100m (Pistorius).  The improvement has come within the last two months, because prior to that, Oliveira's best 100m time was 11.33s.

The leg length - in play, but a red herring

Of course, the current debate is all about his legs, and more specifically, their length.  That is a red herring.  While partly true, there are many reasons to suggest that what Oliveira has achieved in 2013 is not the result of excessively long legs, but some other factor, which has already been proven to exist by scientific research.  Unfortunately, the IPC seem intent on pursuing length as the critical one, with new rules controlling length to be announced soon.

It's unclear what this will mean for Oliveira in the short term, but the problem is that they won't solve the larger problem, and the next athlete to come along with once again push the sport into the same dilemma.

Let's look at the leg length issue in a bit more detail.

London 2012 flashback 

When he defeated Pistorius in the London 2012 200m final last year, the accusation made by Pistorius was that he "couldn't compete with Alan's (long) stride length".  An easy explanation to test, because all it took was counting the strides, and it turned out that Oliveira's stride was not all that long.  In fact, Pistorius took fewer strides than Oliveira, and thus had the longer stride - 92 steps vs 98 steps, for a step length of 2.2 m vs 2.0 m for Pistorius and Oliveira, respectively (remember that a stride is two steps - I counted steps, but report strides later in the discussion).  And the final 100m showed the same pattern - Pistorius' average step length was 2.3 m, compared to 2.2 m for Oliveira.

So, stride length, at least at a superficial level, is not where the advantage came from back then, and it's not the sole explanation now either.

That said, it would be incomplete and false to suggest that Oliveira's leg length should not be the subject of some scrutiny.  In the week leading up to that 200m final, Oliveira revealed in an interview that he had recently increased his blade length by 4cm, taking him from a racing height of 1.77m to 1.81m, and he was clearly relatively taller than his rivals.

To understand what all that means, let's consider how the IPC set the maximum allowable leg length for double amputees.  First of all, it's not an easy task to do - there is no such thing as a "normal height", and when someone does not have legs, then trying to be specific about how tall they would have been is a complex exercise in dealing with ranges.  That's because we don't all share the same limb proportions.

There is an average ratio of say, arms to height, and a similarly average ratio of femur length to total leg length, but these averages don't often apply to elite athletes.  One example is Michael Phelps, the world's greatest swimmer, who stands 1.93m tall and remarkably, wears the same length pants as Hicham el Guerrouj, the world record holder in the mile, who stands only 1.75m tall!

That is, a difference of 18cm in height, with the same leg length.  Such are the variations between people.  One is a swimmer, one is a runner, and they are arguably born to excel in their specific events by virtue of completely different leg to total height ratios.  For pages and pages of similarly mind-blowing stats, I would highly recommended David Epstein's book, "The Sports Gene", which is due out this week.

But for now, let's leave it at the fact that the IPC cannot simply say "You should be X cm tall based on your arm length".

Instead, what they have done is establish a maximum allowable height for each double amputee.  The image below, which was released in the aftermath of the London 2012 controversy, shows the height limits for the key players in this debate.  It invites four thoughts:

Thought # 1 - taller is not necessarily better, and that has important implications

First, notice that Oliveira is allowed race at 185.4 cm, whereas Pistorius was able to go to 193.5 cm.  Presumably, that's a limit based on arm length, modified and improved by femur length to give a total height, which is the absolute maximum for someone who has exceptionally long legs relative to their body (like el Guerrouj).  We know that in London, Oliveira was 181cm, so he was 4cm short of the limit.  He was thus perfectly legal, as I'm sure he is now.  The issue is thus not cheating, but perhaps whether the limits are 'fair'.  

To address that, it's interesting to wonder about why he would stop at 181 cm?  If you're going up from 177 cm as he did, and if longer legs mean better performances (as people somewhat simply suggest), then go to the limit of 185.4 cm. More length, more speed?

The answer to that question is that at some point, going longer becomes counter-productive.  That's because the start becomes so severely compromised (as we saw with Oliveira in London), as well as balance around the bend, that the overall performance gets slower.  Top end speed may be greater, but the net result of longer limbs is less balance and therefore slower times.  Thus, there exists a "sweet spot", an optimal length for each athlete, and that's why none of the top double amputees are competing at their maximum allowable height.  Pistorius, for instance, races at 186 cm.

Thought # 2 - athletes discover the sweet spot by testing, so everyone is "optimized"

The implication of Thought # 1 is that the elite athlete have discovered their optimal sweet spot, because if they didn't, they go maximum length to find more top end speed.  We know from the PR around Pistorius that testing on blades is extensive - he traveled to Iceland often, and representatives of these carbon fiber manufacturers visit athletes for field testing regularly.

Part of the process is discovering how far below the limit the athlete should stop.  So for instance, we should be asking how Oliveira knew to stop at 181 cm prior to London, and why Pistorius was at 186 cm in the first place when he could have gone to 193 cm?  Why not 189 cm?  They had room to play with, but decided not to use it.  The answer is that they're optimized at those 'sub-max' heights.

For Oliveira, however, that may have changed since 2012.  It's conceivable that since his breakthrough (remember that he was just 19 in London last year) he has had more time and more technological support, and thus more opportunity to work out his ideal racing height.  

One source at the IPC reported to me earlier this year that Oliveira had in fact gone shorter, and thus discovered a much faster start and bend performance, driving his times down.  Others are saying he is now even longer - perhaps right up to his 185.4 cm limit.  A curve ball in this debate is that between 19 and 20, he may have grown, and so his upper limit of 184.5 cm from London may have increased, allow him more to play with.  

His 100m performance improvements suggest shorter, because his start is so much better, unless he has improved his balance and co-ordination spectacularly in the last 12 months.  However, we don't know what height he has raced at.  The IPC will, unless they have been grossly negligent in getting the blades measured, and that is surely inconceivable given the obvious focus on them.  They'll have to consider this information as they decide what to do next.  Which leads me on to point 3...

Thought # 3 - the IPC have to change the rule, but how effective will it be, and what do they base the change on?

It's clear that if the current progression continues, the IPC and the IAAF will have to reassess the situation of double-amputees racing in the able-bodied events.  Oliveira won the 400m title at the World Champs this weekend, but with a less than stellar time.  He said after that he doesn't train for the longer distance.  With an Olympic Games coming up in his own country, and with 3 years of preparation, maturity and strength to gain, it's almost inconceivable that he won't at least attempt to run in both Olympic and Paralympic competitions, emulating Pistorius.  Perhaps he will focus on the 200m - another half a second improvement on his 20.66s WR puts him into a final there, with possibilities of a medal should three years produce similar improvements to 2013.  Given that he is only 20, and clearly still in a period of rapid improvement, such an improvement is well within the realms of possibility. 

If he does jump up to the 400m, his chances are even better - the time lost at the start can be recovered over the final 350m, and his top-end speed, which must surely be comparable to Usain Bolt's, as well as remarkable sustained speed in the second half, should see him go considerably faster still.

So, what are the IPC and IAAF to do?  Refer again to the table above, and remember that those maximum height allowances are based on data collected from hundreds if not thousands of people to establish a range of human "norms".  If the IAAF and IPC decide to change them to make Oliveira race at a shorter height, they would have to justify it by saying something along the lines of "We are now adopting mean or average height rather than allowing for extreme individuals within the normal population".  That is, they would have to pretend that extremes like Phelps or el Guerrouj don't exist, and I can't see how that is legally or scientifically defendable.  You have to allow for cases at the extreme end of "normal", which is why the answer to that apparently simple question "What is a normal height?" is so very complex.

Alternatively, they could modify the guidelines slightly, perhaps to 1SD above means, and reduce Alan Oliveira's maximum allowable height subtly.  If it meant he was forced to drop to say, 181cm, he'd be at the same height he was at in London, and that means more of the same debate and performances. 

The point is this:  Because none of the athletes are at the maximum allowable height (see Thought #2), any change in the policy will have to be drastic, or it won't affect them anyway.  And drastic changes mean re-writing the understanding of human anthropometry, possibly discriminating against individuals who are normal but 'extreme', and may thus be impossible to implement.  All in all, very sticky for the IPC.

Thought 4: Leg length possibilities for Oliveira

And then finally, as I return to where I began, this discussion of length may be something of a red herring.  Again, there is no doubt that as the legs get longer relative to total height, the person is more likely to be a successful runner.

However, Oliveira has achieved almost a second of improvement in the 100m within one year.  His 200m performance trajectory is similar.  That invites three possibilities:

1. He is still racing on the same length blades as London (height 181cm).  In this case, his improvement is solely due to training, co-ordination and normal development.  One can still say he has an advantage, but his improvement is distinct from it.
   
   
2. He has changed up, and gone to longer legs, then I find it hard to believe that 3 to 4cm (he only has this to play with, it's not as though he can race at 195cm - see table above) can contribute to that kind of performance.  This is particularly true given that any increased length must surely compromise the start and bend, and so the effect is even larger.  Simply put, it cannot be solely due to running "taller" in 2013
   
   
3. He has changed down, and found a better "sweetspot" that gives him a better start and bend performance, faster overall, with some accepted reduction in top speed.  If this is the case, and he's running at say 179cm, then it's even more of a problem for the IPC and IAAF because whatever they plan to change in their guidelines would need to be even more drastic.

What if stride length is not the factor at all?

But what if it is not in the length at all?  What if that simple exercise of counting his strides, and comparing them to Oscar Pistorius' in London 2012 actually hints at the solution?

Remember, that night, Pistorius took 49 steps on the bend and 43 steps in the home straight.  That is a step length of 2.0 and 2.3 m respectively.  Oliveira, on the other hand, had average step lengths of 1.92 m on the bend and 2.2 m on the straight.  In a race of absolute stride lengths, Oliveira is second-best.

The key, however, is the stride length relative to body height - someone who has excessively and disproportionately long legs will have a longer stride relative to their height, so you can partially test this 'accusation' by comparing stride length to total length.

So, running that logic for 2012, if Pistorius, at 186 cm, takes 230 cm steps, his step length to height ratio is 1.24.  Oliveira, at 181 cm with 220 cm steps, is at 1.22, and so in fact, Pistorius' steps are actually longer, not only in absolute terms, but also relative to his height.  This is the primary reason that I wasn't convinced that Oliveira's advantage was stride length back in 2012, and I'm not convinced now (though I will allow for the possibility that he has since increased his length - see Thought # 4).

The answer is more likely stride speed, not length. And that closes the loop

The ratio is however significant, because it says that Oliveira's advantage, which is now even greater than it was in London 2012, comes not from stride length, but the other important factor - stride speed.  It is the turnover of his limbs that separates Oliveira from the rest of the world, and which has made him a realistic medal chance in able-bodied competitions.

And why is that important?  Well, it closes the loop, bringing us full circle, because the scientific research on Oscar Pistorius showed that the advantage of double-amputee athletes, as a result of super-lightweight carbon fiber blades, is that his limb repositioning speed was "off the biological charts".  Those words were written by Prof Peter Weyand, who tested Pistorius and suggested a 10-12 seconds advantage because of limb reposition times he had never seen before, even in 100m Olympic champions.

Simply, the double-amputee was able to move his limbs so fast that he could then afford to spend more time on the ground, and generate significantly lower forces than able-bodied runners who were going the same speed as him.  The "athletic limit" to sprinting, according to Weyand, a world leader in sprint mechanics, is the ability to apply huge force to the ground.  Pistorius was able to run world class speeds without that limit existing, because his ultra-lightweight limbs allowed him be break another limit - the speed with which the legs could be moved.

Alan Oliveira has taken that to a new level.  When a man is running a 200m race and his strides are about 10% shorter than his rival's, then the only way to run faster than the rival is to have stride speeds that are 10% or more faster.  That's the Oliveira advantage - extra-ordinary speed of leg movement.  He is able to capitalize on the technology more effectively than any runner before him, and may also be able to generate force more rapidly than his predecessors.  The result is less time on the ground, less time in the air to reposition the limbs, and 20.66s and 10.57s performances.

Oliveria - validating the theory, vindicating the research, with no end in sight

Oliveira is, simply put, the validation of scientific theory, and he vindicates the predictions made about what would happen when the pool of athletes with access to carbon fiber blades expanded to include superior athletes.  This was inevitable - it's a rapidly growing sports category, and this is a great thing.  If only they'd kept them separate based on objective evidence, rather than the emotion of the Pistorius case.

Oliveira will one day be beaten by the next generation of double amputee, who will be even faster, and will then re-ignite the same debate.  The problem for the IPC and IAAF now is that they will have to reassess their guidelines in order to slow the runner down.  In other words, Oliveira is too fast, so we have to rewrite the rules.

Effectively, what they would be doing is setting a bar, at say 20.50 s for a 200m and 45 s for a 400m, and saying 'We welcome your participation, but just don't be too fast, or we'll have to change our rules to make you slower'.  It is analogous to putting weights on the bicycles of the top men of the Tour de France, to make the race more competitive, or make Djokovic and Murray play with wooden rackets to slow their dominance of tennis.

Well, the end is not in sight, because just as Pistorius was not going to be the pinnacle of athleticism on prosthetics, why should Oliveira be?  This is progress.  It's human progress.  A normal progression of ability as better athletes emerge.  The IPC and IAAF are looking at the technology, when they should be looking at how the heck they managed to duff the case against carbon fiber blades in the first place. 

Final word - a lot of the above discussion revolves around the very basic analysis of the London 2012 200m final, where I counted the strides for Pistorius and Oliveira.  What should happen is a similar discussion, in even more detail, now that Oliveira is rewriting the record books.

However, that won't happen, because the powers that be don't seem to recognize the importance of gathering the data to inform this kind of discussion.  I can appreciate that they have bigger issues, and may not have the resources to do it themselves.  Certainly, they are custodians over more than just one category and three of its events.  

However, in the build up to the Lyon IPC World Championships, I tried to approach the IPC for permission to analyse Oliveira's 100m and 200m races.  I wanted split times at 10m intervals, so that we could discover just how much time he lost at the start, when he hit top speed and how that top speed compared to Usain Bolt's (I suspect it is the same, or faster).  However, the IPC were not as enthusiastic, and so the study concept was never approved.

What a pity, because now we have to guess - we don't know his leg length, or the limit, or just how he put those world records together.  In time, maybe this debate will force those facts into the open, and that will be a good thing.  But until the evidence emerges, we talk about average stride lengths and stride speeds, which suggest that it's not solely about longer legs (as the public and even some rivals are still proclaiming), but about stride speed.

The evidence is out there, waiting to be found.  For Pistorius, the evidence was found - it showed clearly what was happening.  Why is it paid no attention?

In time, perhaps it will be.  Today, in 10.57s, Oliveira guaranteed that it would be.  There's much still to learn.

Ross

On performance analysis: Common sense, guided

Performance analysis in sport: The guidance of common sense

With the Tour de France now disappearing in the rear-view mirror, I've been weighing up a post on the value of performance analysis as a predictive tool in sport, particularly given the criticism of our (Doc at the Veloclinic, Ammatti, Fred Grappe and Antoine Vayer) recent analysis of the Tour de France.

Throughout the process, I encouraged the use of insight and circumspection when looking at performance metrics, but however strongly the message was emphasized that performance does not constitute proof of doping, there is always a convenient and 'lazy' way to dismiss it as 'pseudoscience' (which is the new "never failed a test" defence, incidentally).  That particular stick (pseudoscience) has been wielded in the context of Pistorius, Armstrong, hydration, barefoot running, running technique and fatigue, but not previously with the extremism seen during the Tour.

So here are some thoughts on the method, and an attempt to create some context around the value of trying to understand the world with imperfect methods (which we all admit they are).

Acceptable uncertainty - performance analysis is never exact

In my work with the SA Sevens Rugby team, we analyse performances.  We analyse opposition patterns, we study their options and tendencies in various phases of the game.  The purpose is to better understand, and thus predict, what they are likely to do.  We can tell our players to expect Samoa to play a certain pattern, whereas Fiji will do the opposite.  The players run onto the field knowing with a reasonable degree of certainty where a lineout throw will go, how the opponent will defend rucks, what they'll attempt on kick-offs and how they are likely to run at us from broken play.

This is the same concept applied to sports the world over.  In the NFL, it exists at perhaps its highest level, where expert analysts break down seemingly random patterns and discover 'tells' and methods to pre-empt opposition plays.

However, everyone involved recognizes that it is not formulaic.  There is uncertainty, and this is accepted.  Performance analysis, regardless of the sport, is always an exercise in probability because it happens in uncontrollable conditions, and so it adds value by adding insight rather than by conclusively and accurately predicting what will happen.  I can't give you the error bars on this kind of analysis, because sport is fluid and contextual, and so even the 'safest' bets are vulnerable to unique and specific situations.  The smaller the data set, the greater the error, but it's hard to assign a value to it.

The result is that a player cannot run onto the field with a text-book in their mind and then fail to use common sense, as well as all their other senses, to assess a given situation.  Playing off memory, stats and data is a disaster, when you have eyes, ears and insight.  Just because the pre-match analysis said that the opponent would do X does not mean options Y and Z are off the table, and so a 'smart' player is needed to discern the actual event from the performance analysis predictions.  On that note, we've had players who can't seem to grasp this, and who take to the field with only one option in their minds.  They prove to be inflexible and are probably better off with less information.  For most, however, the guidance is beneficial, if interpreted sensibly.

If I tell Novak Djokovic that Andy Murray is likely to serve down the T on points where he is leading but out wide when behind on the scoreboard (for instance, this may happen on 75% of points, with an error), Djokovic would be foolish to leap wide during the ball-toss, but he'd also be foolish to discard the information because there's "uncertainty".  Inch, don't leap.

In cycling, there seems to have been far tooo much "leaping", in the sense that people seem to have either blindly embraced or discarded the concept of performance analysis, whether it be for the metric time up a mountain, estimated power output, or the physiological implications of that performance, without recognizing the necessary nuance.

Keep the other senses

So performance analysis in rugby, football, tennis, American football and basketball may be quite different from performance analysis is cycling and running in many respects, but it is similar in one important aspect - it does not replace common sense or give permission to disengage every other sense in order to rigidly accept a black and white version of the world of sport, which is clearly nuanced and everyone recognizes this.  For this reason, it never constitutes proof.

Why people would want to accept such extremism is beyond me.  That inflexibility fosters blindness and prevents insight.  In effect, people who dismiss performance metrics and their implications as "worthless" because we are estimating power output are analogous to a blind man, offered 40% vision, but who refuses it because he only wants 100% sight.  It's 20/20 or nothing, and I believe that's a flawed and narrow understanding of the world.  It would be the same as a head coach saying to his analysts "If you can't guarantee with 100% certainty what my opposition are going to do, I don't want to know it at all".

Before I'm seen to be proclaiming that say, 40% is "good enough", I will say once again that we all recognize that it's not.   We want 90%, 100%.  That's why the process began with a call for the data, biological and performance.  That's because the "blurred" image offered by 40% vision, similar to the "performance pixellation" I wrote about after many stages in the 2013 Tour de France, may well lead a person into many blind alleys and unseen obstacles.

However, what seems overlooked is that people still have other senses - they have small, hearing and touch.  And they should also have some common sense.  So 40% vision added to other senses makes anyone better off than they were in total blindness.  Unless, of course, said blind man decides that with his new-found 40%, he is going to ignore every other sense.  This would be equally foolish in the opposite direction.

So if we can gain any insight at all, and combine it with our other senses, then just like our SA 7s rugby players, or the NFL footballers or a basketball player, we can run onto the field or court with more confidence, provided we retain the ability to interpret every situation as it develops for what it is.

As applied to the 2013 Tour de France

Therefore, when Chris Froome rides away from a field on the first week of the Tour at a power output that is higher than benchmarked, and produces a time that puts him in the company of known dopers, we should ask questions of that performance.  But we cannot conclusively use it to prove that he is doping.  That would be extremism, and it would be wrong.  It's for this reason that I have written, and still believe, that Vayer is too far to the extreme when he declares performances 'mutant'.  They are not - they're still within the realms of physiological plausibility, though on the high side.  That's what Fred Grappe concluded when provided access to Froome's data, and it is the conservative and correct approach.

Similarly, Rodriguez or Quintana should be regarded with some 'wonder' for getting progressively better, and eventually exceeding historical benchmarks during the race.  Quintana, incidentally, produced the best performance of the entire Tour on its very final climb of Semnoz, benchmarked against historical norms using the pVAM method (pVAM, while I'm discussing it, is just that - a benchmarking method that for the first time, makes Semnoz comparable to Alp d'Huez even though it had never been done in the Tour.  And that's progress - for all the criticism of the pVAM method, it opens that possibility.  Now it needs evolution)

A process, and evolution with uncertainty

Without the analysis of pVAM and the estimates of power output, plotting those power outputs against duration, and historical reference points, these performances have no context.  Therefore, performance analysis asks questions, it does not answer them.  In time, those answers may emerge, and performance analysis can help us to evaluate those answers as realistic or false.  But with an eyes tightly shut approach, we are guessing.  For instance, is it normal to show higher power outputs in week 3?  We don't know.  Had we gathered data for 20 years, we'd have a pretty good idea.

The point is, this is all a process.  It's never going to be perfect, but if we halt evolution based on imperfect then we'll never move forward.  If Henry Ford and others had decided not to proceed with mass produced cars because he had in mind the perfect luxury vehicle, then we'd still be sitting on horse-drawn carriages.  I think that Doc, Ammatti and even Vayer (despite some differences in the interpretation) are doing cycling a favour by calling for transparency and starting a discussion.  I honestly believe that performance analysis is making progress in cycling as a result of their efforts.  Again, it's not perfect.  There is uncertainty. But then, progress dies of boredom when there is certainty.

It doesn't deserve outright dismissal, and it doesn't warrant embracing as conclusive proof of anything (nor does it ever ask to be seen this way).  So I'd thank all those for participating in the discussion.  I hope it advances insight and enjoyment of the sport (it certainly does for me).  I applaud people for wanting accuracy, I think that is always good.  And if I have ever drawn a conclusion that goes beyond what the error of the estimates does not allow, I'd expect to be called out on it.  Run me out of town i I say that a performance is proof of doping without recognizing its context or explaining that kind of extreme statement.

But equally, I'd hope that people read the articles (yeah, I know, they're long) and then consider my interpretation of the numbers, and the explanation, the nuances, and then avoid the extremism reaction.  We all have other senses, after all, so we can accept uncertainty and navigate with only partial vision, provided we engage those senses, most of all common sense.

Two final parting thoughts

That said, two final thoughts on the 2013 Tour, from a performance analysis perspective:

1.  These are the SRM data for five Tour performances, compared to our estimates using two methods.  One is the method of Ferrari, using pVAM, the other is the CPL method, which pretty closely approximates Vayer's method.  Once again, they're from Ammatti Pyoraily's vast bank of performances:

Perfect? No.  But not nearly as unusable as some have suggested.  You can decide for yourself whether those estimates are worthless or not.  I'd point out that the estimations are just as likely to underestimate power than overestimate it (3 vs 2 for CPL), so sometimes estimation gives benefits to the cyclist.  Collectively, if we wish to avoid performance pixellation, the average error for these five performances is 0.6%.

The timing of climbs was criticized because it's based on TV observations.  An error of a few seconds, far smaller than any of the other errors, so it's a bizarre criticism that emerged in the Tour.  If we were hand-timing Usain Bolt in a 10-sec sprint, it'd be different, but not over 30 minutes or more.  Wind?  Of course.  When you're going in a straight line with tailwind for 90% of the race route, like Boston Marathon runners experienced in 2010, wind blows the whole thing out the water.  I dare say it's a lot less significant, based on SRM data, in the variable Tour geography.

Is it acceptable to be within 1-3% per climb?  That depends what one wishes to conclude.  If the pursuit is proof of doping, then of course it isn't, but even exact SRM data wouldn't "prove" anything anyway.  We can always do better - you'll notice that Ferrari's method tends to overestimate power, and that's because for lighter riders and faster speeds, the formula he developed doesn't account fully for drag.  That's why Doc at the Veloclinic has been trying to develop a better method for performance prediction, taking into account the components - all part of the process of getting better, and that's the evolution that will make 2014 better than 2013.

But I think on the whole (and again, the above table shows only five 2013 comparisons, but we've pooled this with other data from Sorensen and the 2010 Tour de France where Horner provided his SRM data) the error is consistently in that 1 - 3% range, and I'd argue that the method is not as poor as some have suggested.

More to the point, the exact data wouldn't allow conclusive proof of doping or non-doping anyway, so given that the interpretation is subject to nuance and context, the error in the estimate can be accepted at this level.  It's an acceptable level of uncertainty.  That's the performance uncertainty aspect I wrote of earlier - we may not have 100% vision, but we have senses.  We just need to use them fully as we add to them, uncertainty and all.

2.  This whole performance analysis concept became heated and controversial because it seems that many in the English speaking world had a vested interest in the success of specific riders.  Much like the most aggressive defence during the Lance Armstrong era was coming from the USA, some of the most vocal defense of Froome was, understandably, coming from the UK.  And even British media.  There is nothing inherently wrong with this.

By the end of the Tour, Quintana and Rodriguez were at the same level as Froome on Ax-3-Domaines, and Quintana even surpassed it on Semnoz to produce the best climb of the race, statistically speaking.  Even accepting the constraints of "performance pixellation", the trend was quite clear.

And in some parallel universe, hypothetically speaking, I wonder how the numbers and estimates would have been perceived if Quintana and Rodriguez started the Tour in that condition?  What if Contador had joined them at speeds as fast as Armstrong and Ullrich a decade before?  I dare say that had it been Quintana and Rodriguez accelerating clear on Ventoux and Ax-3-Domaines, the whole process of our performance analysis would have found a different story from the very first mountain.  A new script, certainly one in which we'd be doing less defensive explanation than we've done.  Would those performances have attracted a similar skepticism from the UK press as Froome did from the French media (by all accounts)?  Certainly, and that's the key - the performance warrants questions, not accusation, and measuring it, imperfection and all, can only be helpful.

Ultimately, though, the final word on the 2013 Tour is that we shouldn't be accusing, just wondering.  And given cycling's history, and the fact that those entrusted with running the sport have shown themselves to be unable to clean it up, we cannot simply believe (blindly) in miracles this time around.  So we wonder, reasonably, and use some kind of performance metric to gain some insight.  Proof, no.  But equally, not worthless.

On that note, crank punk nails the problem facing cycling's appeals for trust.  There've been scandals in the past, and as sure as anything, there will be doping scandals in the future.  Paul Kimmage also recently gave this interview - he's over on the cynical extreme, but his thoughts are eloquent and with some caution, well worth listening to. Jump to the 10:00 mark.

On that note, thanks for reading the Tour coverage, let's do it again in a year.  Next up, the IAAF World Championships in Moscow.

Ross

Oliveira 20.66s: A double amputee will soon medal in able-bodied Olympics

Double amputee sprinters version 2.0: Alan Oliveria runs 20.66s 200m 

The next generation of double-amputee sprinters have arrived, sooner than expected. Alan Oliveira of Brazil today won the 200m world title in 20.66s, improving the previous world record for double-amputees by 0.64s.

Oliveira, who shot to prominence after defeating Pistorius amidst blade controversies at the London's Paralympics, added the 200m WR to his 100m WR set a month ago (10.77s, 0.16s faster than previous).

So, we now see the successor to Pistorius, running 0.14s and 0.64s faster than Pistorius over 100m and 200m, respectively.  How much faster will he be over 400m?  The answer is "substantially".  Even if he does not continue increasing that advantage over the previous benchmark as distance increases, he will run ± 44.3 s.  Chances are, it grows even larger.  If you saw the race today, and the final 100m, you'll appreciate why.

So, a prediction, and you heard it here first (actually, if you've been following this debate about carbon fibre blades, you'll have heard it here years ago):

If he desires to run against able-bodied athletes, Alan Oliveira will win a medal in the 400m at the 2016 Olympic Games.  He is still only 20, with much strength to gain, but his recent improvements are staggering - 0.56s in the 100m and 0.80s in the 200m since the London Paralympics.  That suggests much more to come, and it suggests a medal in the able-bodied Olympics in 2016.  Of course, he may not wish to, which would be interesting.  If it is not him, it may be the next athlete, but it will happen.

This is not a criticism of Alan Oliveira, who deserves credit for his performances in the Paralympic events.  He will become the best amputee sprinter in history, if he is not already.  This is however an issue of the cross-over of amputee and able-bodied competitions, and the implications of this kind of progress for that decision.

The decision to allow Pistorius his wish to compete in able-bodied events was always going to have predictable repercussions in the future.  These were unfortunately obscured by marketing, emotion and the incomplete (dishonest?) presentation of science.  Allied to this was the media's almost total inability and lack of will to challenge the PR campaigns and to ask the difficult questions while they fell over themselves to tell the heart-warming, popular story.  (I hope that this section of the media will tell the same story for Oliveira or his successor when they run sub-43 seconds for 400m.)

The repercussions come more clearly into view today, because the evolution of a young sport means that better athletes will emerge, and times will continue to plummet. No doubt the authorities will scramble to look at the technology, but they'd be wasting their time - this is not an issue of technology changing - it's too soon for that to have happened significantly, and I'd hazard that Oliveira has had less R&D support than Pistorius so is likely still on technologically inferior equipment - he's just better at using them.  It's the athletes improving, because that's how a young sport evolves.

By allowing the cross-over to happen, the authorities and media, who were so starstruck by Pistorius that they couldn't see this, made the incorrect starting assumption that Pistorius belonged, physiologically, at the highest level of able-bodied sprinting.  The science was however clear - this assumption was wrong and Pistorius was getting between 5 and 10 seconds advantage in a 400m race, but the decision was made regardless.

It was thus inevitable that Pistorius' performance would soon be beaten, even with the same technology.  Oliveira today revealed just how much further we may still have to go - a 0.64s improvement in a single 200m race is astonishing, and it puts into context the true capacity of Pistorius and his performances.  And of course, on top of this, we know that technology progresses.  The dual combination of technology and a better athlete pool creates a situation almost impossible for authorities to control - they can be grateful we are only talking about one athlete at a time.  For now - in time, depth will be added to the dilemma.

So, do we now see a reassessment of the decision because an athlete may suddenly be "too fast"?  How can a decision be reversed based on the weak reason of "technology" when that technology was not even understood to begin with?  How far backwards can the IAAF bend on this?  And what happens when the next generation emerges, even faster than Oliveira?  Do we repeat the back-tracking again, in which case the entry requirement for participation in able-bodied events becomes that "you're just not quite fast enough?"  A theoretically farcical situation, but not all that far off, judging from 20.66s of sprinting today.

The issues around the performance advantages of carbon fiber blades was always going to be confirmed by the clock.  It's ticking a little more quickly than many might have thought.  Is anyone listening?

Ross