The Barefoot running round-table discussion from UKSEM: Thoughts from "inside"

Thoughts from the Barefoot running round-table discussion at UKSEM: An inside view

Many of you will probably know by now that at the recent UKSEM conference in London, I chaired a session called "Natural Running – advantages and disadvantages. A Round Table Discussion".

The protagonists in the debate were:

• Prof Daniel Howell, an anatomy professor from Liberty (USA), known as the "barefoot professor"
• Simon Barthold, who formerly worked as a podiatrist but who now works in biomechanics and is Asics global research consultant
• Prof Benno Nigg, one of the world's leading biomechanists
• Dr Mathias Marquard, a clinician and running coach (who would go on to become the voice of reason in many of the more hostile aspects of the debate, as I'll describe!)
• Prof Daniel Lieberman, evolutionary biologist from Harvard, who as you may know, recently published the Nature studies looking at how habitually shod and barefoot runners differ, and who wrote a key paper on how humans are adapted (skeletally and physiologically) to run long distances

The debate concept

That's a pretty high-profile "cast", including some of the world leaders in their fields.  Then there was me, chairing a debate which everyone knew could easily become an argument!  To begin with, academics don't enjoy this method of getting theories out.  I know this because three of the five on the panel said as much before and after, and I suspect it's mostly because scientists like to work according to a linear 'template' that says you first introduce the question, then you describe the gaps in the literature, then you systematically plug those gaps using your experiments, then you present data and move towards understanding.

A debate, however, is not linear, but circular, or more like a "vortex", in that different threads are whirling around together, and I think it can be an uncomfortable way to discuss data.  The risk is always that every statement made by one person contradicts another's views, and they want to respond to it, so we would basically get sucked down and never move forward.  

I can appreciate this, but I think it's also an excellent way to accelerate understanding for the audience (but then you'll have to tell me this if you were there), because it super-condenses a big topic into a discussion and for that reason, I think it works rather well.

Controlling it, however, was a nerve-jangling prospect.  Before the debate, Asics (who sponsored the UKSEM conference, which included naming rights to this debate, which is commendable) had worked with PR teams to try to manage it, because they were understandably concerned about excessive hostilities (lively debate is good, outright hostility is not!) and also about one or two of the members dominating the discussion.  "Everyone must get a say".  So I had to ensure that neither happened, and with this being such a polarized topic, and knowing that there were pro- and against- academics on stage, I confess to being quite anxious about it.  My approach to this of course is to joke and try to entertain (why be dull when you can liven it up?), but that didn't stop me from almost forgetting the names of the first two speakers as I introduced them!  

Buy or sell?  The first provocative question

Nevertheless, I got past that first little hurdle, and then the debate kicked off with a simple question, based on the media portrayal of the barefoot debate.  The question was: "If a runner picks up a magazine or newspaper, they are seeing the following statement: 'Shoes are evil.  They do not help, they may even cause injury.  Barefoot running is natural, and will help prevent injury, and therefore everyone should be encouraged to run barefoot'.  Do you buy or sell this concept?"

That's a very provocative question, and as mentioned, I hate how this issue has been polarized.  In fact, if there's anything you take out of this website, it's that when people polarize a debate into one of two extremes, they're both wrong.  In science, there's always middle-ground, and a significant "but", whether it's related to barefoot vs shod running, training vs talent, dehydration vs overhydration, doping control, carbs vs fat in diet.  But an extreme question was necessary to get the ball rolling.

So from my vantage point, this is what I saw from the five responses:

Only Daniel Howell outright bought the concept.  He explained that he has been LIVING barefoot for 6 years, spending 95% of his time without shoes.  He is an advocate not only for barefoot running, but for barefoot living.  His main argument, which I'll get to shortly, is that barefoot running is the "natural state"

All the other speakers were relatively non-committal.  Prof Benno Nigg was most neutral, saying that every year, he asks his students this question in a final exam: "Does barefoot running prevent injuries?", and the only answer he accepts for a good grade is "I don't know because we don't know".  

It became clear right away that Prof Nigg was not about opinions.  At all.  He is perhaps the world's leading biomechanist, and has had in excess of 300 publications on the subject, plus dozens of books, and is really all about the evidence.  Which is a bit of a problem in a round-table discussion, but his absolutely neutral answer did two things a) it highlighted that this is a debate that really does lack evidence, and b) that he was going to be the "go to guy" for scientific fact, not opinion!  If I wanted to kill the debate, ask Prof Nigg for his opinion!  

Professor Daniel Lieberman said the same thing - we don't have the evidence yet, but there is enough theory there, as well as the 'birth' of a line of evidence that may begin to steer us towards it.  At this point, they mostly agreed with one another.

"Buy, but keep the receipt for a refund"

Let me digress and state my view on that question, since I didn't get to state it at UKSEM!  I believe that EVERYONE can benefit from some barefoot running.  That is, I think that barefoot running is, at worst, a good training modality that may have benefit for running performance, even when wearing shoes.  We know from research and simple experience that there are significant differences in muscle activation and loading patterns when running barefoot, and these are all potentially favourable, even if barefoot running is used only as a training method.  In fact, I'd go so far as to encourage all runners to try barefoot running, even if it is only during a warm-up or cool-down, or once a week for a short time.

For some people, I do believe that barefoot running may be the answer to their injury problems.  I think there is enough there to suggest that some individuals who struggle in shoes will fare much better without them.  However, here's the catch - we don't fully know who they are, and more importantly, why they benefit.  We can surmise that it has to do with the change in loading on different joints (as shown by Lieberman and countless others), the proprioception, the strengthening of joints, and so forth.  But we simply don't know.

By extension then, there may well be people who simply cannot adapt to barefoot running.  In fact, I'm certain this will be the case.  They break down and get new injuries, usually of the ankle, calf, Achilles tendon or foot.  And these individuals may never take fully to barefoot running.  I still think that the fact that they do pick up these injuries indicates the 'stress' and if the body adapts positively to stress, then they too can benefit from barefoot training, if not fully immersing themselves in it.  However, for them, it must be recognized that shoes may be the only thing enabling them to run (regardless of whether it is "natural" or not). 

And the one thing I would implore the "barefoot evangelists" to recognize is that just because it works for them, does NOT mean it will work for everyone, and so don't make the same mistake we often  accuse shoe companies of making when they gave everyone motion-control and stability devices.

The key thing, I believe, is that barefoot running allows us to study shod running better.  It invites the realization that perhaps it is running form/technique that is crucial, and by comparing and contrasting the two, we might understand why people run the way they do, and where the risks may originate.

So in short, my answer to that question is "Buy barefoot running as a concept, try it out as a training modality, but keep the receipt so that you can return it if you don't find the "fit" right for you.  At worst, you'll discover a new muscle activation pattern, a new and effective training method, and potentially, changes to running form that will help you run better, in shoes"

Back to the debate...

The tale of two Daniels, and confusing a hypothesis with evidence

The first real point of disagreement in the debate came with a theoretical discussion of "natural running".  That's a vague, all-encompassing term, and we could have debated it for an hour, all by itself.

But let's just go with it at a superficial level, for now!

Prof Daniel Howell, the barefoot professor, was asked to elaborate on the evidence for barefoot running.  Remember, the panel had all agreed that evidence was lacking, so the next question I put is "what evidence do you need, and what do you have?"

Howell's response was that "barefoot running is natural".  We are not born with shoes, our ancestors did not run in shoes, and it is therefore natural for us to run barefoot too. To live barefoot, in fact.  What is not always as clear is that somewhere along this logic, "natural" becomes a synonym for "better".  Howell at one point challenged Simon Barthold, asking him to justify why he said that people need shoes (I agree with Barthold on this one, by the way.  At least for some people). 

Howell believes that we don't, because it's natural to be barefoot, and that this must be better.  I'm paraphrasing of course (I'm sure I'm open to criticism about context here, but that's basically his position, as anyone who heard it will say, I'm sure).

There are fundamental problems with this idea.  First, he makes a big error of confusing the hypothesis with the evidence.  All he has at this early stage is a theory that can lead to a hypothesis.  Prof Lieberman (the other Daniel in the discussion) has a better understanding of this.  I had a long lunch with Lieberman the day before, and we discussed the entire debate, and this came up.  My point is that we didn't have anti-biotics until recently either, and the result was that many people died as a result of "natural" causes, and the invention of these medicines was clearly a positive step.  To equate "natural" with "better" is a very basic mistake to make.

Second, the problem that I think Howell has is that he has not recognized that being barefoot as a runner exists in a larger context, and that context includes about 100 things that make us different from our ancestors.  For example, we sit at desks for 8 hours a day, we sleep on comfortable mattresses, we drive, and we "hunt" our food in supermarkets and not in bushlands, we play in shoes (when we're not playing on computer games), and we grow up in them and then at 30, we are faced with a possible change (as a result of this debate).  Not one of those things happened before, but every one of them COULD be a contributing factor to injury risk.  In other words, weakness of supporting muscles and tendons as a result of years of disuse and TV-watching might mean that being "natural" is a more risky option that being in shoes.  There is a real possibility, as stated earlier, that some people need shoes in order to run.  The notion that being barefoot works for everyone today because it may have worked for everyone a long time ago is a leap of faith.

Lieberman recognizes this, and it means that he can appreciate that the anthropological finding about what we had on our feet many years ago is not proof of what we should wear today, it's only a starting point for a hypothesis that can be tested.

The skill aspect of running

The consequences of making the over-simplification of "natural = better" are significant.  For example, I presented on barefoot running last week, and suggested that barefoot running is a skill that has to be learned.  If, like Howell, you believe that natural barefoot running is better, then you don't need to recognize the skill aspect of running.  In fact, we know this because he called this skill idea "bull" in a Twitter post recently.  The problem is this: The scientific evidence produced by Lieberman shows very clearly that people who have run in shoes for many years do NOT run barefoot the same way as people who have been barefoot for a long period.  Thus, there is some learning, some adaptation that takes place, and whether we can all achieve this adaptation remains to be seen.

That is, take the shoes off and you get a pretty dire picture - these individuals continue to heel-strike, at least for a short time, which predisposes them to very high ground reaction forces and a huge vertical loading rate, both of which are surmised to be linked to injury risk.  Also, the muscles and tendons are unconditioned for barefoot running, and are then suddenly loaded differently, which further increases the injury risk.

Anecdotally, and from my own coaching (and Lieberman's observations which he shared with me over lunch), new barefoot runners make some fundamental errors because they don't adopt what seems to be the optimal barefoot running gait right away.

If they are running "naturally", however, and we buy into the theory that it's how it was intended by nature, then I fear that we're missing a huge piece of the puzzle, because it is quite clear that not all barefoot running is equal either.  And so when people "fail" when barefoot and are surprised, it's probably (this is opinion at this stage - evidence will come) because of faults in the gait, the most obvious of which seems to be over-striding and deliberately forcing a forefoot landing by plantar-flexing at the ankle (pointing the toe down).

This is a recipe for disaster, since it loads the ankle joint on a contracted muscle, and probably led to so many Pose runners breaking down when we monitored a group who'd just learned this technique.  I suspect the same risk exists for barefoot running, but it happens "naturally" and if you adopt the historical hypothesis as "proof", then you are blind to this possibility.  On the whole, I think that Howell does a disservice to his own advocacy by being blind to the evidence.

But very importantly, if making the transition to barefoot running should be viewed as a skill that has to be learned, then why not view all running as a skill?  This is an interesting question and kind of leads into where this debate will go in the future, I think, but more on this later.

The cushioning debate

The biggest point of difference came around a discussion on cushioning and impact forces.  Lieberman had the day before presented his Nature study findings, where the impact transient was absent when running barefoot with a forefoot landing, and explained this using an effective mass model.  Basically, what he is saying is that when you run in this way, and land forefoot, a lower effective mass decelerates on ground contact, than when you land on the heel.  To illustrate this, he used the analogy of a pen falling vertically to the ground compared to a pen falling at an angle of 45 degrees.  A greater effective mass "stops" when the pen lands vertically.

This is sound logic, of course.  But it led to an argument, because I think Simon Berthold misunderstood the point of the analogy.  He had printed off Lieberman's website explaining barefoot running and adamantly criticised Lieberman's explanation.  I think it's fairly clear what the analogy was meant to illustrate, and I think there is no doubt that landing on the heel does involve a significantly higher impact transient (just look at the difference in magnitude - it's 700% higher for heel-striking than forefoot landing).

There are some very theoretical questions about the use of this model, and Benno Nigg commented on this, but overall, this was an argument that didn't help the debate, because it obscured the point about impact forces.  I think an analogy was mistaken for a literal explanation and Lieberman's website became the focus of argument when we might have been discussing the mechanics a little better.  I eventually had to dismiss this discussion and move on, because nothing good was going to come out of it, because Berthold had pursued it down a blind alley to a point where Lieberman couldn't defend the analogy anymore, and Lieberman was getting flustered as a result.  End of discussion.

There was some disagreement over cushioning as well.  Lieberman's "model" is that part of the benefit of being barefoot is that it reduces the loading rate and effectively removes the impact transient.  For this to be beneficial, as opposed to having purely academic value, it has to be shown that these forces on landing are linked to injury. There is some evidence of this from Irene Davis' work, and Lieberman mentioned in the debate that the higher impact forces and loading rates have been linked to injuries like shin-splints and potentially knee problems.  

Benno Nigg was of the opinion that it wasn't the impact forces, but rather the forces in mid-stance that were more important.  His work suggests that the active forces may be more important, and these are very similar for shod vs barefoot running.  One of his big lines of evidence, of course, is to show that the degree of cushioning in the shoe (or running surface) actually doesn't change the impact forces.  His explanation for this was perhaps a little rushed, but has to do with the idea that muscle can be "tuned" by activation levels to make it optimal for a given surface.  The end result is that whether you run on hard or soft surfaces, the impact is relatively "benign".  This became a fairly high-brow biomechanical discussion, which definitely doesn't work in a round-table debate, and so wasn't explored as well as it perhaps needed to be.

Voice of reason: What do shoes really need?

The voice of reason in this debate, as I mentioned, was Mathias Marquard.  A highly acclaimed German author of running/coaching books, and a clinician, he adopted a very neutral and sensible view in the debate.  His experiences as a runner and a coach had brought him full circle, from going fully barefoot 15 years ago, to now recognizing the value of barefoot running, but not prescribing it.  He seems to have found the practical balance, and complemented the scientific discussion very well.  He made this point very eloquently on many occasions, and as a result, when I felt the debate was getting off track, he was the "go to guy" to bring it back with pragmatic viewpoint.  He was very valuable, mostly because of his pragmatism (and humour!)

It was Marquard who brought up a really interesting question when he said that we need to ask very seriously what shoes actually need to have for running?  Do they need massive cushioning?  Do they need stability devices?  Do they need motion control gadgets and built-up medial arch supports?  Do they need rigidity?  The answer to all these questions, in his opinion, was "No", and that was one of the most important points to come out of the discussion.  It was a point that the whole panel agreed on. There is a perception of needing all these aspects, but no evidence for them, and a real possibility that we're better off without them.

On the cushioning, Nigg and Lieberman both agreed, for their different reasons, and I think on the side of massive motion-control, it's become increasingly clear that we don't need all the devices that used to be common.  The shoe industry has already picked up on this, incidentally, and the number of heavy, bulky shoes available has, at least in my estimation, come down enormously compared to a decade ago.

The practical approach

The final point of debate was the practical approach to transitioning barefoot.  It was a thread throughout the debate, and right upfront, Simon Barthold asked me the question "If I were to design an experiment to test barefoot running, where a group of runners will do 45 minutes of barefoot running, would my University's Ethics Committee approve that research?".

The answer of course, is no, unless they didn't know any better, because we know that 45 minutes of barefoot running in a population of shod runners is guaranteed to cause injury!   This was put forward to Barthold, presumably to illustrate the risks of barefoot running, which is quite true.  However, it doesn't say anything about whether barefoot running is good or bad - that's a separate question.  For example, if I wrote a proposal saying that I would be putting a group of overweight heart-attack victims on exercise programmes consisting of 30 min a day, that study would also be rejected, but we know that exercise is excellent and even prescribed for this group!

So the point is that it's not bad just because it's risky.  It's that it's risky.  Simple as that.  There is risk and reward, and the practical implication of this is "How do I make the transition?"

This is where, once again, I believe it's vital to recognize the skill aspect, or at least the learning process, and to understand that we don't all learn the same way (and nor should we).  Daniel Howell was of the impression that going barefoot first is the best approach.  Others, like Barthold, would advocate that you run in minimalist shoes first, lightweight trainers perhaps, then racing flats, to manage the transition.  There is really no right or wrong answer here.  I think it can work either way, as long as one is very cautious.  

You could, for example, build up to say 40 minutes over 3 months, but basically viewing yourself as a beginner runner, starting out with something as basic as 1 min run, 1 min walk for 10 minutes.  And then systematically increase as you adapt.  Or, like Lieberman did, you can do your normal run, but within sight of home, just take off your shoes and finish the last few minutes barefoot.  Do this every second run, each time from slightly further out, and you'll be up to a full run in about the same time.

Change management and running form

I think the key is that while there is no prescribed way, there is a concept, and the concept is that you have to manage the change as though you were doing a training regime for the very first time.  It's almost impossible to tell a guy who is running 70km a week to go back down to 10km for a few weeks.  He won't do it - he might try, but he'll still err on the high side, and then I think many runners will become injured as a result.  So again, it takes recognition that barefoot running is not the solution simply because it's natural, but rather that it has to be learned and adapted to, and then not to simply run barefoot because it's natural and assume that it'll work itself out.

For example, I think it's important to condition the calf muscles before even running.  I also think you have to be aware of over-striding and avoid the temptation to actively force the landing onto the forefoot.  Let gravity handle the landing.  In fact, I think the worst thing to do is to cognitively tinker with running technique, particularly how the foot strikes the ground.  I think incremental change will work for most people, whereas wholesale changes that work at a cognitive level equal disaster for most (which is the problem I have with Pose).

There are many other points about running form, and this is probably where this debate will go in future.  Nobody knows what "perfect running form" is just yet, and the problem is that it may be individualized based on a set of say 50 different inputs.  So what is perfect for me is unlikely to work for you, and this is the reason that some runners are injury free and others are not, I suspect.  A runner with glut. medius weakness for example, might succeed with one form, but will fail using "perfect" or better running form, and so on.  Injuries are multi-factorial (flexiblity, imbalances, strength etc) and so running form to prevent them will certainly be multi-factorial too.

However, I do think it is wise to at least consider HOW you run.  As mentioned, barefoot running is not by itself the answer.  It's a means to discover the answer, perhaps, and for some people, it may go on to become the solution.  But for most, it's a good way to accelerate the discovery of better running, to strengthen and condition differently, and then to benefit from that later on.

Conclusion - evidence to fill the space between what is known and needs to be known

To wrap up the debate, I said something along the lines of that at that moment, there is a great debate going on, but with many gaps.  There is a space between what we know and what we hypothesize, and that gap will be filled by future research.  Some of that is on the go already - my lunch with Lieberman was heavily focused on research that he is now doing, and the research that I will soon be doing to get to the bottom of the 'skill' aspect of barefoot running (and thus running as a whole) and also on the long-term injury prospects of barefoot running.  That research is coming!

In the meantime, this kind of debate is very valuable, if anyone was there and has some feedback or comments, I'd welcome them.  I'm sure my perspective from the round-table will differ from yours in the audience.  So as always, thoughts welcome!

UKSEM wrap

The next thing to do is to discuss UKSEM Day 2, which is the day that featured some of the highlights of the conference.  Prof Yorck Olaf Schumacher presented on the biological passport, Daniel Coyle presented on better ways to practice and learn, and so I need to summarize those.  And of course, there was David Millar's excellent talk on his doping.

But that will come in due course!

Ross

For those not yet saturated by the barefoot topic (which I'll leave alone for now!), check out the following articles from this site:

• A presentation on barefoot running, given at the Sports Science Institute of SA recently

• A detailed article on the mechanics of barefoot running and the concepts behind it

• MOST RECENT:  I hosted a Q & A on the Sports Science Institute of South Africa's Facebook page this morning, taking questions on barefoot running from the public.  You can read the whole exchange here.  

This is actually quite a cool concept, the Facebook Q & A, so look out for more of those in the future!

Ross

Triglycerides, VLDL, and industrial carbohydrate-rich foods

Below are the coefficients of association calculated by HealthCorrelator for Excel (HCE) for user John Doe. The coefficients of association are calculated as linear correlations in HCE (). The focus here is on the associations between fasting triglycerides and various other variables. Take a look at the coefficient of association at the top, with VLDL cholesterol, indicated with a red arrow. It is a very high 0.999.

Whoa! What is this – 0.999! Is John Doe a unique case? No, this strong association between fasting triglycerides and VLDL cholesterol is a very common pattern among HCE users. The reason is simple. VLDL cholesterol is not normally measured directly, but typically calculated based on fasting triglycerides, by dividing the fasting triglycerides measurement by 5. And there is an underlying reason for that - fasting triglycerides and VLDL cholesterol are actually very highly correlated, based on direct measurements of these two variables.

But if VLDL cholesterol is calculated based on fasting triglycerides (VLDL cholesterol  = fasting triglycerides / 5), how come the correlation is 0.999, and not a perfect 1? The reason is the rounding error in the measurements. Whenever you see a correlation this high (i.e., 0.999), it is reasonable to suspect that the source is an underlying linear relationship disturbed by rounding error.

Fasting triglycerides are probably the most useful measures on standard lipid panels. For example, fasting triglycerides below 70 mg/dl suggest a pattern of LDL particles that is predominantly of large and buoyant particles. This pattern is associated with a low incidence of cardiovascular disease (). Also, chronically high fasting triglycerides are a well known marker of the metabolic syndrome, and a harbinger of type 2 diabetes.

Where do large and buoyant LDL particles come from? They frequently start as "big" (relatively speaking) blobs of fat, which are actually VLDL particles. The photo is from the excellent book by Elliott & Elliott (); it shows, on the same scale: (a) VLDL particles, (b) chylomicrons, (c) LDL particles, and (d) HDL particles. The dark bar at the bottom of each shot is 1000 A in length, or 100 nm (A = angstrom; nm = nanometer; 1 nm = 10 A).

If you consume an excessive amount of carbohydrates, my theory is that your liver will produce an abnormally large number of small VLDL particles (also shown on the photo above), a proportion of which will end up as small and dense LDL particles. The liver will do that relatively quickly, probably as a short-term compensatory mechanism to avoid glucose toxicity. It will essentially turn excess glucose, from excess carbohydrates, into fat. The VLDL particles carrying that fat in the form of triglycerides will be small because the liver will be in a hurry to clear the excess glucose in circulation, and will have no time to produce large particles, which take longer to produce individually.

This will end up leading to excess triglycerides hanging around in circulation, long after they should have been used as sources of energy. High fasting triglycerides will be a reflection of that. The graphs below, also generated by HCE for John Doe, show how fasting triglycerides and VLDL cholesterol vary in relation to refined carbohydrate consumption. Again, the graphs are not identical in shape because of rounding error; the shapes are almost identical.

Small and dense LDL particles, in the presence of other factors such as systemic inflammation, will contribute to the formation of atherosclerotic plaques. Again, the main source of these particles would be an excessive amount of carbohydrates. What is an excessive amount of carbohydrates? Generally speaking, it is an amount beyond your liver’s capacity to convert the resulting digestion byproducts, fructose and glucose, into liver glycogen. This may come from spaced consumption throughout the day, or acute consumption in an unnatural form (a can of regular coke), or both.

Liver glycogen is sugar stored in the liver. This is the main source of sugar for your brain. If your blood sugar levels become too low, your brain will get angry. Eventually it will go from angry to dead, and you will finally find out what awaits you in the afterlife.

Should you be a healthy athlete who severely depletes liver glycogen stores on a regular basis, you will probably have an above average liver glycogen storage and production capacity. That will be a result of long-term compensatory adaptation to glycogen depleting exercise (). As such, you may be able to consume large amounts of carbohydrates, and you will still not have high fasting triglycerides. You will not carry a lot of body fat either, because the carbohydrates will not be converted to fat and sent into circulation in VLDL particles. They will be used to make liver glycogen.

In fact, if you are a healthy athlete who severely depletes liver glycogen stores on a regular basis, excess calories will be just about the only thing that will contribute to body fat gain. Your threshold for “excess” carbohydrates will be so high that you will feel like the whole low carbohydrate community is not only misguided but also part of a conspiracy against people like you. If you are also an aggressive blog writer, you may feel compelled to tell the world something like this: “Here, I can eat 300 g of carbohydrates per day and maintain single-digit body fat levels! Take that you low carbohydrate idiots!”

Let us say you do not consume an excessive amount of carbohydrates; again, what is excessive or not varies, probably dramatically, from individual to individual. In this case your liver will produce a relatively small number of fat VLDL particles, which will end up as large and buoyant LDL particles. The fat in these large VLDL particles will likely not come primarily from conversion of glucose and/or fructose into fat (i.e., de novo lipogenesis), but from dietary sources of fat.

How do you avoid consuming excess carbohydrates? A good way of achieving that is to avoid man-made carbohydrate-rich foods. Another is adopting a low carbohydrate diet. Yet another is to become a healthy athlete who severely depletes liver glycogen stores on a regular basis; then you can eat a lot of bread, pasta, doughnuts and so on, and keep your fingers crossed for the future.

Either way, fasting triglycerides will be strongly correlated with VLDL cholesterol, because VLDL particles contain both triglycerides (“encapsulated” fat, not to be confused with “free” fatty acids) and cholesterol. If a large number of VLDL particles are produced by one’s liver, the person’s fasting triglycerides reading will be high. If a small number of VLDL particles are produced, even if they are fat particles, the fasting triglycerides reading will be relatively low. Neither VLDL cholesterol nor fasting triglycerides will be zero though.

Now, you may be wondering, how come a small number of fat VLDL particles will eventually lead to low fasting triglycerides? After all, they are fat particles, even though they occur in fewer numbers. My hypothesis is that having a large number of small-dense VLDL particles in circulation is an abnormal, unnatural state, and that our body is not well designed to deal with that state. Use of lipoprotein-bound fat as a source of energy in this state becomes somewhat less efficient, leading to high triglycerides in circulation; and also to hunger, as our mitochondria like fat.

This hypothesis, and the theory outlined above, fit well with the numbers I have been seeing for quite some time from HCE users. Note that it is a bit different from the more popular theory, particularly among low carbohydrate writers, that fat is force-stored in adipocytes (fat cells) by insulin and not released for use as energy, also leading to hunger. What I am saying here, which is compatible with this more popular theory, is that lipoproteins, like adipocytes, also end up holding more fat than they should if you consume excess carbohydrates, and for longer.

Want to improve your health? Consider replacing things like bread and cereal with butter and eggs in your diet (). And also go see you doctor (); if he disagrees with this recommendation, ask him to read this post and explain why he disagrees.

Sports Science 2011: Talent vs training and Oscar P

Sports science in the media in 2011: Training, talent, doping and Oscar Pistorius

So yesterday was Day 1 of the fantastic UKSEM conference in London.  I gave a presentation on Sports Science in 2011, and that presentation is embedded in the post below.  I am a terrible judge of my own presentations, so I'll just say that mine went OK and hope that it did.  I always know instantly all the things I haven't explained clearly, when I was clumsy, when I repeated myself and when the point I was trying to make didn't quite come off!  But hopefully you can read quietly what I spoke about and it is better than the "live performance"!

I covered some of the more topical stories of the year, but given that I only had 30 minutes, I had to pick three, and they were:

1. The Kenyan dominance of the marathon, which provided a nice lead in to the training vs talent debate
2. Doping in cycling, in the context of how doping control changes doping behaviour
3. Oscar Pistorius, and the scientific cover-up and hatchet job he and his band of "scientists" got away with

The presentation again lacks my voice-over - I may at some stage do a "voice-over" when I have more time, but for now, it should suffice as a read through.  Below, I elaborate on part of the talk (the talent vs training part.  I may, in the future, do the same for the Pistorius section).

Email subscribers click here to be taken to site to view presentation. All others, click on the grey button, wait for loading, then hover over "More" and click "Fullscreen"

Sports Science in 2011 UKSEM on Prezi

The 10,000 hour concept

The biggest talking point, at least in the discussion I had with delegates afterwards, was the Training vs Talent debate (the first part of the talk).  Here, the only reason I included this was because I saw that Matthew Syed who wrote the book "Bounce" was on the programme after me, and his talk was called "The Science of Success".  So I decided that it would be good to have a little bit of science on the topic, because he doesn't provide it in support of his "training-sufficiency" position.

Effectively, Syed's thesis is this:  Genes and talent are over-rated, and great performers, whether they are sportsmen, doctors, musicians or businessmen, achieve expert performance not because of genetic factors or "talent", but because they accumulate enormous volumes of deliberate practice.  He has a few examples of this, and makes a compelling case, at least on the surface.

But when you really interrogate what he is saying, then you realise that the reality is that he is saying that in order to succeed at something at the highest level, to become an expert performer, you need to practice.  OK then... nobody should be surprised at this, and nor would they be.  The problem is that his (and Gladwell's) position seems to exist outside of a world where genetic factors also have an influence, and it's this exclusivity in his thinking that forces a closer look.

Unnecessarily polarizing the complexity of performance by ignoring genes and talent

So the issue is not that they advocate hard work and a lot of training, it is that they downplay the importance of talent or innate ability.  I emphasized this in my own talk, but it bears repeating - if Syed is correct, and the secret to success is training and accumulating many years and hours of practice, then Talent ID is a waste of time and money.  We should rather spend that money on getting 100 more children to train, because they should all (or most) become champions, provided they get through the required hours.

Note that this also completely overlooks the fact that children tend to do what they are good at, and that simply running a child through a "10,000 hour factory" is an imagined concept only.  I guess the real question is why are some children good at something almost within the first moments that they start it, thereby encouraging them to do it more?  It seems to me that this could be an innate difference too...

In a competitive sport, training is obviously a crucial determinant of success

But the theory that practice is important is so obvious it doesn't need emphasis.  As soon as you have competition, then within a narrow range of individuals (the top 10 tennis players, or the Olympic finalists, for example), training will become a crucial determinant of who wins and loses.

In "a small pond", where there is no competition, it's possible to succeed with talent alone.  Just think back to school level athletics, when there's no competition, a young athlete can show up on the day and dominate to win.  But the higher the level, the better the competition, the more important training becomes.  And those individuals who get attempt to by on talent alone are washed away in this more competitive landscape.  Syed made this point, and of course he's correct.  But the key is that the athlete who succeeds all the way to the Olympic podium is the one who dominated without training (that is, he's talented or genetically gifted), but then also trained incredibly hard to stay a champion as the competition intensified.  In otherwords, he has BOTH talent and training. 

In fact, I challenged him on this after his talk, and basically made the point that if he had walked into that venue today, with 200 people in the audience, and asked them to please raise their hands if they thought that sporting success was ENTIRELY genetic, he would have been the only person with his hand in the air.  He may have been laughed out the room had he tried to propose that the current belief is that success is all genetic.  Everyone knows that it is not.

Yet he seems to have arrived at this belief that someone out there believes that expert performance is achieved solely on the basis of genes and natural talent. Now, maybe I missed this in my studies, but I have not once heard this theory.  The established theory in sports science is that many, many years of training are required to hone and refine skills and physiology in order to become a world or Olympic champion.  The reality is that sports science does NOT believe that it's ALL in the genes, and nor do they believe that it's all about training.  So the first problem with the 10,000 hour concept is that it attacks a straw man that need not exist.

To polarize the debate the way that he (and others, most notably Malcolm Gladwell) have done is unnecessary, and it has quite important financial and policy implications for where money should be spent by sports federations and coaches to help improve performance.  Their books and emphasis are not without merit, certainly - they have emphasized how important it is that we recognize that not all young aspirant athletes develop equally, and that we may need to consider how coaching is provided to more children to prevent some from falling through the cracks.  But sports science already knew this.  What these books have done is spawn a theory that now says that practice is sufficient for expert performance, which it clearly is not.

The work of Elferink-Gemser, who presented today after Syed, confirmed this, because she has been studying the progress of young sportspeople for 10 years, and has found large differences between children in terms of how they respond to training sessions and coaching.  But more important, she finds that it is possible to predict which children will become professional within the first few years of them entering the sports academy.  In other words, by the time children are 15 or 16, there are already differences between those who will become "great" and those who are merely "good".  It has little to do with accumulating the "magical 10,000 hours".   The mere fact that these young athletes have such different responses to training tells you that you can't generalize potential performance to a group, and that the outcome of training will also differ between individuals.

The three 'failings' of the 10,000 hour, "practice is sufficient" model

I think there are three key points about this 10,000 hour concept:

Firstly, if you can find ONE case of an exception, then you have disproved the "rule".  That is, if you can find a guy who trains 10,000 hours but doesn't succeed, then you have shown that it's not sufficient.  Or, if you can find a guy who trains only 5,000 hours, but who does succeed, then you have shown that it is not necessary.

And the truth is that both of these cases exist, everywhere.  Baker has shown it in triathlon, it has been found in chess (so it's not only "physiological" sports where innate ability seems to matter), and it has been found in football, wrestling, field hockey, skeleton.  Every single sport has examples of athletes who have shot to the top within a few years of starting the sport, and it is littered with athletes who fail despite doing 20,000 hours.  Today I spoke with a woman whose husband taught music for a school for gifted musicians in New York, and they discover children who within months of starting are playing at near-professional expert levels.  Now, unless those children have managed to get 10,000 hours of training in in one hour (by discovering how to slow down time), they have achieved expertise well before the theoretical minimum.

There's no question that talent, or innate ability, or genetics, play a role.

The second point is that there is no good evidence at all to suggest that 10,000 hours is required for expert performance.  The study that is always cited is a violin study, which found that expert violinists had accumulated an AVERAGE of 10,000 hours by the time they went to music school, whereas those who were merely good had done 8,000 hours.  Two problems.  First, you can't infer cause from this kind of retrospective study.  Who is to say that the talented, genetically gifted violinists didn't train more BECAUSE they had more talent from the age of 8?  Perhaps their innate ability was the catalyst to get them more practice (mom sends them for lessons, and they enjoy it).  And secondly, the study showed absolutely no indication of ranges or variance.  So we don't know whether there are some people who became experts with less training, and nor do we know whether some failed despite doing their 10,000 hours, because the author did not show that data.  I hope I don't have to emphasize that if either of these people exist, then the theory is wrong.

Which brings me to the third point about this theory - it is entirely unfalsifiable.  To the "evangelists" who proclaim that anyone can become an expert if they just practice enough, it's too easy and too convenient to simply dismiss the exceptions because they clearly didn't practice in the right way.  So if someone has done 25,000 hours and has not succeeded, then they simply say "He obviously didn't practice the right way".  Or if someone becomes an expert in only 3,000 hours (which happens, all the time), they say "He must have compressed his 10,000 hours into a third of the time".

So it's a completely unfalsifiable theory.  It cannot be proven, and it cannot be disproven.  Therefore, it does not belong in science.

What the science does say - "responders" and "non-responders"

What does belong in science are studies that look at how different individuals have been shown to adapt to training.  And sure enough, those studies exist, though Gladwell and Syed would never admit to them.  The Heritage study, for example, took hundreds of unrelated people and gave them standardized training programmes, and then measured the responses.

The result?  A complete spectrum, ranging from those who show absolutely no response to training, all the way to those who improve by more than 40% as a result of training.  And as expected by the scientific theory, the difference between these people can very reliably be linked to genetic factors.  Specifically, there are Single Nucleotide Polymorphisms (SNPs) which account for half this training resopnse.  Individuals who have 9 or fewer of the identified 21 SNPs are the "low-responders", whereas people who have 19 or more of these SNPs are "high responders".

The answer therefore is that it's not about having different genes, it could also be about having different variants of the same gene, the result being that you and I show completely different responses to training.  And you have to ask yourself, if you are a coach, would you rather have an individual who is a "high responder" or a "low responder"?  And more importantly, if you have $100,000 to invest in a sport, where do you spend it to find a champion?  On talent ID, to find those "high responders", or do you believe that anyone can succeed if you just spend the money to help them all do 10,000 hours of training?  In terms of policy, it's clear that the science, at least for this physiological variable, points you in the direction of finding the right people to spend the money on.  And that means understanding the value of genetic factors to performance.

And just to dispel the idea that skill-based activities benefit more from training, when you look at studies in chess, you find that there is a massive difference in the time taken to reach Master level - some do it in 3,000 hours, some have been at it for 25,000 hours and counting.  In darts, 15 years of practice (almost 15,000 hours) only accounts for 28% of the variability in performance.  In otherwords, 72% of the difference in performance between two players cannot be explained by the hours spent training.  In darts...

In sport, countless studies show that elite athletes get to the top within 6,000 hours of starting their sport, and the success of Talent ID programmes proves that talent transfer (something that is impossible if the 10,000 hour theory is correct) exists. 

Conclusion - training is the realization of genetic potential

The bottom line is that a theory of deliberate practice gives us one important message - if you want to succeed, practice.  Coaches around the world breathe a sigh of relief, you're not redundant.  But this is so obvious, I guess the reminder is always good though.

But the application of this theory, and the dismissal of genes that it somehow seems associated with, is a huge oversimplication and wrong, at least for sports.  Syed today argued about school performance, and about how teachers should downplay the idea that some children are more "talented" with numbers or better at mathematics than others.  And that's fine, because whatever helps people improve is great.  But if we're in the business of finding Olympic champions, then this theory has no place in its polarized form.

Not only this, but it could be extremely damaging.  If you take it literally, and you buy into a 10,000 hour concept, then you'll be obliged to start training a child at the age of about 10, because you need them to become world-class in their early-20s.  All good and well, except the evidence shows quite clearly that the earlier you start intensive training, the LESS likely you are to succeed.  And so there are all kinds of implications for how we manage children's sport participation.

The ultimate conclusion, in my opinion (and as always, I welcome your views), is that training is nothing more than the realization of genetic potential.  Without both, you will not become an Olympic champion (in a competitive sport, that is).  Training will improve everyone, and so everyone should be encouraged to train.  But genetic factors determine where we start, how we respond to training (trainability), how much training we can tolerate before burnout or injury (because let's face it, chess players rarely get injuries that force 6-week layoffs, like stress fractures), and finally, where the "performance ceiling" exists.

Training will get you to your ceiling, you'll realize your genetic potential.  But will it win you a medal?  Only if you chose your parents right!

Ross

P.S.  For a more detailed discussion of these issues, please do read the previous two articles I wrote on the subject:

1. A look at the 10,000 hour concept.  What does it say, and why it fails to pass the test of validity
2. The evidence for how genes influence elite sporting performance

Barefoot running: An overview

Barefoot running presentation: Overview of the science 

So last night, at the Sports Science Institute of South Africa where I'm based, I gave a presentation on barefoot running, aimed at the public.  A big topic, obviously, always guaranteed to pull a good crowd and generate lively debate.  Which it did.

It's a topic I've covered in great detail before on this site, with approaches ranging from a look at the evidence for shoes, to the findings of the latest barefoot running research.  I fly to London tonight for the UKSEM conference, where I'll be chairing a debate on running injuries (among other talks), and which will probably be one of the highlights of the meeting, since it includes Daniel Lieberman and Benno Nigg, both of whom have done research on this subject.  So there'll be more to come from that, no doubt.

But for today, I just wanted to share with you the presentation that I did last night.  It will lack the sound and my explanations, of course, but most of it should be fairly self-explanatory.  For those who want to read through a more detailed description, you can read the article I wrote after the ACSM meeting earlier this year - most of the concepts covered in the presentation below are also described in that article.

I would say that the three key points about this whole debate are:

Evidence linking the mechanics to the injury outcome still lacking

There is as yet no conclusive evidence that either proves or disproves the benefits of shoes or barefoot running, or links the mechanical characteristics of barefoot running to a reduced risk of injury.  That is, for all the work showing how impact forces and loading rates are reduced when barefoot, it remains to be proven that this leads to lower injury rates.  I began last night's talk by saying that this was the first time a "scientific" presentation would be given with so little conclusive scientific evidence!  There are plenty of theories, of course, and some are sound, but we await the real evidence for the injury and performance side of the debate, which will come from long-term, prospective studies.

Recognize that running barefoot may be a skill and that people acquire skills at different rates (or not at all)

The evidence so far suggests that barefoot running produces some potentially beneficial changes, mostly related to how running form and kinetics are altered without shoes.  However, it also points to a potentially large group of people who, when running barefoot, may have increased risk of injury, especially early on - these are the people who continue to heel-strike when barefoot, and who may "force" a forefoot landing, leading to huge strain on the calf muscle and Achilles tendons.

The key point is that barefoot running (and thus running in general) should be recognized as a SKILL, and it is clear that we do not all have the ability to acquire skills equally.  Those who do not may be substantially worse off, and require much longer to make the adjustments.  Whether they should even try is a good question.

The issue however is not necessarily whether barefoot running is "good for you", but rather whether barefoot running helps us understand anything about how we run that might help us reduce injury risk.  If barefoot running provides these answers for a given runner, then of course it would be enormously beneficial.  But it may be that simply learning about barefoot running helps runners in shoes just as much!

It's also vital to recognize that huge differences may exist between individuals:  some adapt very quickly to minimalist shoes or barefoot running - these people are the "responders" and they tend to go on to become "evangelists" who tell everyone to throw away their shoes!  At the other extreme, however, are non-responders, who, for reasons unknown, will battle to run without "traditional shoes".  In both cases, we have to be careful about generalizing the "extreme" observation to the general population.  That's the mistake shoe companies made when telling everyone they needed all manner of gadgets in their shoe, and it's a mistake that people now make when advocating barefoot running.

We do not fully understand why some people adapt faster than others.  The studies required in the future need to assess how biomechanical and neuromuscular changes are learned and relearned when running barefoot, and then to establish whether this impacts on injury risk.  Those will come, in time.

Worth a try, or inclusion into training. But respect the length of the investment: Change management

In terms of advocacy, I believe that barefoot running will help most runners.  It may be as part of a training programme where barefoot running helps with adaptation because it loads the joints differently, activates muscles in different patterns and therefore provides a good training impulse. For some, barefoot running (or minimalist shoes) will go on to become the "only way".  For others, it will remain a training technique, and that's fine too.  But I'd certainly look at incorporating it, just for the training adaptations it provides.

The key, as mentioned in #2 above, is to recognize that going from shoes to either minimalist shoes or barefoot is a skill and involves a significant change.  Therefore, it's essential to respect the time that it will take to fully adapt to the different loading stresses associated with running either barefoot or in minimalist shoes.  I've given an illustration of a programme in the presentation, where I've 'budgeted' 12 weeks to build up to 40 minutes of solid running (plus 2 to 4 weeks of preparation).  Some people may take even longer than this - the question that has to be asked then is whether it's worth it?  Is a 6-month intervention worth the benefit, when the benefit hasn't yet been clearly established?  I doubt it.

Nevertheless, if you're sold on the idea of giving it a try, recognize that you're making a long-term investment, and that if you simply continue your normal training barefoot, you're pretty much guaranteed to get injured!

More to come in the future, I am sure.  Looking forward to meeting Lieberman for a few runs along the Thames, and we will be discussing the future research that needs to be done!

Until then, enjoy the presentation below!  Again, click the grey arrow, hover over "More" and click "Fullscreen".  Email subscribers click here to visit the site to view presentation

Ross

Barefoot running on Prezi

Read the previous article on barefoot running with more detailed explanations of the topics covered in the presentation

My transformation: How I looked 10 years ago next to a thin man called Royce Gracie

The photos below were taken about 10 years ago. The first is at a restaurant near Torrance, California. (As you can see, the restaurant was about to close; we were the last customers.) I am standing next to Royce Grace, who had by then become a sensation (). He became a sensation by easily defeating nearly every champion fighter that was placed in front of him. In case you are wondering, Royce is 6’1” and I am 5’8”. The second photo also has Royce’s manager in it – that is his wife. Their children’s names both start with the letter “K”. I wonder how big they are right now.

I think that at the time these photos were taken I weighed around 200-210 lbs. Even though I am much shorter than Royce, I outweighed him by around 40 lbs. Now I weigh 150 lbs, at about 11 percent body fat, and look like the photo on the top-right area of this blog - essentially like a thin guy who does some manual labor for a living, I guess. A post is available discussing the "how" part of this transformation (). I only put a shirtless photo here after several readers told me that my previous photo looked out of place in this blog.

My day job is not even remotely related to fitness instruction. I am a college professor, and like to think of myself as a scholar. I don’t care much about my personal appearance; never did. At least in my mind, putting up shirtless photos on the web should not be done gratuitously. If you are a fitness instructor, or an athlete, that is fine. In my case, it is acceptable in the context of telling people that a few minutes of mid-day sun exposure, avoiding sunburn, yields 10,000 IU of skin-produced vitamin D, which is about 20 times more than one can get through most "fortified" industrial foods.

Royce is such a nice guy that, after much insistence, he paid for the dinner, and then we drove to his house and talked until about midnight. He had told me of a flight the next morning to Chicago, so I ended the interview and thanked him for the wonderful time we had spent together. I had to talk him out of driving ahead of me to I-405; he wanted to make sure I was not going to get lost at that time of the night. This was someone who was considered a demigod at the time in some circles. A humble, wonderful person.

Royce helped launch what is today the mega-successful Ultimate Fighting Championship franchise (), which was then still a no holders barred mixed martial arts tournament. At the time the photos were taken I was interviewing him for my book Compensatory Adaptation, which came out in print soon after (). The book has a full chapter on the famous Gracie Family, including his father Helio and his brother Rickson.

I talked before about the notion of compensatory adaptation and how it applies to our understanding of how we respond to diet and lifestyle changes (). In this context, I believe that the compensatory adaptation notion is far superior to that of hormesis (), which I think is interesting but overused and overrated.

The notion of compensatory adaptation has been picked up in the field of information systems, my main field of academic research. In this field, which deals with how people respond to technologies, it is part of a broader theory called media naturalness theory (). There are already several people who have received doctorates by testing this theory from novel angles. There are also several people today who call themselves experts in compensatory adaptation and media naturalness theory.

The above creates an odd situation, and something funny that happened with me a few times already. I do some new empirical research on compensatory adaptation, looking at it from a new angle, write an academic paper about it (often with one or more co-authors who helped me collect empirical data), and submit it to a selective refereed journal. Then an "expert" reviewer, who does not know who the authors of the paper are (this is called a "blind" review), recommends rejection of the paper because “the authors of this paper clearly do not understand the notion of compensatory adaptation”. Sometimes something like this is added: “the authors should read the literature on compensatory adaptation more carefully, particularly Kock (2004)” - an article that has a good number of citations to it ().

Oh well, the beauty of the academic refereeing process …

UCT Research in 2011: Wrap-up

Wrapping up the 2011 academic year: UCT/ESSM research cocktail party conversation topics

Such a busy time recently, hence the big gap between posts!  I am off to London tomorrow for the UKSEM Conference, where I will be presenting three talks.  The first is on Sports Science in the media in 2011, where I'll tackle the topical stories of the year (Oscar Pistorius, doping in cycling and the Kenyan marathon dominance and the genetics vs training debate).

The second is on the fallacy and oversimplification of the 10,000 hour concept, because I saw from the conference programme that Matthew Syed of "Bounce" fame would be presenting a talk called "The Science of Success", and I feel it's important to at least counter this with some science....

That is, to present the proper scientific view of the role of genes in performance, because unlike Syed has said, genes do not play little to no role in performance, and it is definitely not "all about the training" (for more on this, you can read the posts I wrote back in August this year).

And then the third talk will be on doping and the limits to performance.  I guess it's topical again now, with the "sub-2 hour marathon debate" once again opening up, albeit very prematurely.  If you followed the Tour de France coverage on site these last few years, you'll also be aware of the idea that there is a physiologically believable performance limit, and that's the topic of the third talk at UKSEM.

Then I'm also going to chair a round-table discussion on running injuries, which features Daniel Lieberman (of barefoot running fame) and Benno Nigg (biomechanics guru), among others.  As a matter of fact, I'm giving a presentation tonight at the Sports Science Institute of SA on barefoot running, which I'll share with you as soon as it is done.

So all in all, UKSEM should provide plenty of fodder for the site in weeks to come.  Assuming I can find the time to post!

ESSM 2011: The academic year ends

But for today, I just wanted to do a recap of the year in research at the University of Cape Town, where I am jointly employed.  The unit is the Exercise Science and Sports Medicine research unit (ESSM for short), and last week, we held our annual year-end function.  This is a function where all those eager and interested "guinea-pigs" who have volunteered to be studied as part of our research get to come for a finger-dinner and listen to a few presentations on our research.  It's just feedback and information, mostly to say thank you for their time (and blood, sweat, tears and occasional muscle sample), but also to get sports science out, to translate it in a way that makes it more accessible.

My mission from the evening has always been to give each person one item of "cocktail party conversation".  That is, next time they're at a social event, whatever it is, they need to be able to say "Hey, I heard about this really interesting stuff being studied at Sports Science, where they're looking at..."

So my presentation on the evening was to summarize what the ESSM Unit had been doing in 2011.  Consider that we have about 40 people involved in research at a time, and that's no easy task - it means effectively trying to summarize 40 years of research, assuming each person has had a productive year, into a 30 min presentation!

But below is that presentation.  I created a mock-up newspaper, with "articles" featuring some of the research areas, and then I did a short interview with the relevant scientist responsible.  Each "interview" was 2 to 3 minutes long, where they elaborated on their work, a few questions, and then moved on as I took the audience through the "newspaper".

There's no sound, unfortunately, so the detail is absent.  But this is really just a filler and to showcase some fo the work that the unit is responsible for.  It doesn't get nearly enough air-time, in most instances.

Enjoy, and speak to you again from London!

Ross

P.S. Presentation may take a while to load.  Just click the grey "play" arrow, hover your cursor over "More" and click "Full-screen".


Oh, and if you get this in an email, please CLICK HERE to be taken to the site where you can watch the presentation

ESSM feedback 2011 on Prezi

The China Study II: How gender takes us to the elusive and deadly factor X

The graph below shows the mortality in the 35-69 and 70-79 age ranges for men and women for the China Study II dataset. I discussed other results in my two previous posts () (), all taking us to this post. The full data for the China Study II study is publicly available (). The mortality numbers are actually averages of male and female deaths by 1,000 people in each of several counties, in each of the two age ranges.

Men do tend to die earlier than women, but the difference above is too large.

Generally speaking, when you look at a set time period that is long enough for a good number of deaths (not to be confused with “a number of good deaths”) to be observed, you tend to see around 5-10 percent more deaths among men than among women. This is when other variables are controlled for, or when men and women do not adopt dramatically different diets and lifestyles. One of many examples is a study in Finland (); you have to go beyond the abstract on this one.

As you can see from the graph above, in the China Study II dataset this difference in deaths is around 50 percent!

This huge difference could be caused by there being significantly more men than women per county included the dataset. But if you take a careful look at the description of the data collection methods employed (), this does not seem to be the case. In fact, the methodology descriptions suggest that the researchers tried to have approximately the same number of women and men studied in each county. The numbers reported also support this assumption.

As I said before, this is a well executed research project, for which Dr. Campbell and his collaborators should be commended. I may not agree with all of their conclusions, but this does not detract even a bit from the quality of the data they have compiled and made available to us all.

So there must be another factor X causing this enormous difference in mortality (and thus longevity) among men and women in the China Study II dataset.

What could be this factor X?

This situation helps me illustrate a point that I have made here before, mostly in the comments under other posts. Sometimes a variable, and its effects on other variables, are mostly a reflection of another unmeasured variable. Gender is a variable that is often involved in this type of situation. Frequently men and women do things very differently in a given population due to cultural reasons (as opposed to biological reasons), and those things can have a major effect on their health.

So, the search for our factor X is essentially a search for a health-relevant variable that is reflected by gender but that is not strictly due to the biological aspects that make men and women different (these can explain only a 5-10 percent difference in mortality). That is, we are looking for a variable that shows a lot of variation between men and women, that is behavioral, and that has a clear impact on health. Moreover, as it should be clear from my last post, we are looking for a variable that is unrelated to wheat flour and animal protein consumption.

As it turns out, the best candidate for the factor X is smoking, particularly cigarette smoking.

The second best candidate for factor X is alcohol abuse. Alcohol abuse can be just as bad for one’s health as smoking is, if not worse, but it may not be as good a candidate for factor X because the difference in prevalence between men and women does not appear to be just as large in China (). But it is still large enough for us to consider it a close second as a candidate for factor X, or a component of a more complex factor X – a composite of smoking, alcohol abuse and a few other coexisting factors that may be reflected by gender.

I have had some discussions about this with a few colleagues and doctoral students who are Chinese (thanks William and Wei), and they mentioned stress to me, based on anecdotal evidence. Moreover, they pointed out that stressful lifestyles, smoking, and alcohol abuse tend to happen together - with a much higher prevalence among men than women.

What an anti-climax for this series of posts eh?

With all the talk on the Internetz about safe and unsafe starches, animal protein, wheat bellies, and whatnot! C’mon Ned, give me a break! What about insulin!? What about leucine deficiency … or iron overload!? What about choline!? What about something truly mysterious, related to an obscure or emerging biochemistry topic; a hormone du jour like leptin perhaps? Whatever, something cool!

Smoking and alcohol abuse!? These are way too obvious. This is NOT cool at all!

Well, reality is often less mysterious than we want to believe it is.

Let me focus on smoking from here on, since it is the top candidate for factor X, although much of the following applies to alcohol abuse and a combination of the two as well.

One gets different statistics on cigarette smoking in China depending on the time period studied, but one thing seems to be a common denominator in these statistics. Men tend to smoke in much, much higher numbers than women in China. And this is not a recent phenomenon.

For example, a study conducted in 1996 () states that “smoking continues to be prevalent among more men (63%) than women (3.8%)”, and notes that these results are very similar to those in 1984, around the time when the China Study II data was collected.

A 1995 study () reports similar percentages: “A total of 2279 males (67%) but only 72 females (2%) smoke”. Another study () notes that in 1976 “56% of the men and 12% of the women were ever-smokers”, which together with other results suggest that the gap increased significantly in the 1980s, with many more men than women smoking. And, most importantly, smoking industrial cigarettes.

So we are possibly talking about a gigantic difference here; the prevalence of industrial cigarette smoking among men may have been over 30 times the prevalence among women in the China Study II dataset.

Given the above, it is reasonable to conclude that the variable “SexM1F2” reflects very strongly the variable “Smoking”, related to industrial cigarette smoking, and in an inverse way. I did something that, grossly speaking, made the mysterious factor X explicit in the WarpPLS model discussed in my previous post. I replaced the variable “SexM1F2” in the model with the variable “Smoking” by using a reverse scale (i.e., 1 and 2, but reversing the codes used for “SexM1F2”). The results of the new WarpPLS analysis are shown on the graph below. This is of course far from ideal, but gives a better picture to readers of what is going on than sticking with the variable “SexM1F2”.

With this revised model, the associations of smoking with mortality in the 35-69 and 70-79 age ranges are a lot stronger than those of animal protein and wheat flour consumption. The R-squared coefficients for mortality in both ranges are higher than 20 percent, which is a sign that this model has decent explanatory power. Animal protein and wheat flour consumption are still significantly associated with mortality, even after we control for smoking; animal protein seems protective and wheat flour detrimental. And smoking’s association with the amount of animal protein and wheat flour consumed is practically zero.

Replacing “SexM1F2” with “Smoking” would be particularly far from ideal if we were analyzing this data at the individual level. It could lead to some outlier-induced errors; for example, due to the possible existence of a minority of female chain smokers. But this variable replacement is not as harmful when we look at county-level data, as we are doing here.

In fact, this is as good and parsimonious model of mortality based on the China Study II data as I’ve ever seen based on county level data.

Now, here is an interesting thing. Does the original China Study II analysis of univariate correlations show smoking as a major problem in terms of mortality? Not really.

The table below, from the China Study II report (), shows ALL of the statistically significant (P<0.05) univariate correlations with mortality in 70-79 age range. I highlighted the only measure that is directly related to smoking; that is “dSMOKAGEm”, listed as “questionnaire AGE MALE SMOKERS STARTED SMOKING (years)”.

The high positive correlation with “dSMOKAGEm” does not even make a lot of sense, as one would expect a negative correlation here – i.e., the earlier in life folks start smoking, the higher should be the mortality. But this reverse-signed correlation may be due to smokers who get an early start dying in disproportionally high numbers before they reach age 70, and thus being captured by another age range mortality variable. The fact that other smoking-related variables are not showing up on the table above is likely due to distortions caused by inter-correlations, as well as measurement problems like the one just mentioned.

As one looks at these univariate correlations, most of them make sense, although several can be and probably are distorted by correlations with other variables, even unmeasured variables. And some unmeasured variables may turn out to be critical. Remember what I said in my previous post – the variable “SexM1F2” was introduced by me; it was not in the original dataset. “Smoking” is this variable, but reversed, to account for the fact that men are heavy smokers and women are not.

Univariate correlations are calculated without adjustments or control. To correct this problem one can adjust a variable based on other variables; as in “adjusting for age”. This is not such a good technique, in my opinion; it tends to be time-consuming to implement, and prone to errors. One can alternatively control for the effects of other variables; a better technique, employed in multivariate statistical analyses. This latter technique is the one employed in WarpPLS analyses ().

Why don’t more smoking-related variables show up on the univariate correlations table above? The reason is that the table summarizes associations calculated based on data for both sexes. Since the women in the dataset smoked very little, including them in the analysis together with men lowers the strength of smoking-related associations, which would probably be much stronger if only men were included. It lowers the strength of the associations to the point that their P values become higher than 0.05, leading to their exclusion from tables like the one above. This is where the aggregation process that may lead to ecological fallacy shows its ugly head.

No one can blame Dr. Campbell for not issuing warnings about smoking, even as they came mixed with warnings about animal food consumption (). The former warnings, about smoking, make a lot of sense based on the results of the analyses in this and the last two posts.

The latter warnings, about animal food consumption, seem increasingly ill-advised. Animal food consumption may actually be protective in regards to the factor X, as it seems to be protective in terms of wheat flour consumption ().