Barefoot running, shoes, and born to run

The barefoot running debate: Born to run, shoes & injury: the latest thinking

One of the more interesting, and certainly topical presentations at the recent meeting of the American College of Sports Medicine in Denver was a symposium on barefoot running.  It was led by Irene Davis and Daniel Lieberman, both advocates for barefoot running and top scientists in this field.  Lieberman in particular is something of a 'legend' in the field, and two years ago, he gave the prestigious keynote address at the ACSM meeting.

Since then, the area has moved on, thankfully.  Most recently, Lieberman's group did some fascinating work on the barefoot running concept in runners accustomed to shoes or running barefoot, and that's the focus of this post, along with some thoughts on the concepts underlying barefoot running.  A lot of the time, I'll play devil's advocate, because I believe in Lieberman's findings, and the theory behind barefoot running is sound.  But there are some "loopholes", and I'll end with those.

Not just a fad, and certainly not only for the niche

There are more than a few people who have dismissed barefoot running as a fad.  And many will have labeled it a niche concept, practiced by a very small percentage of runners.  That's only partly true.  If you think that barefoot running has nothing to do with you, think again.  You may not have discarded your shoes, but the truth is the the shoes you are running in have already been influenced by the concepts that drive the barefoot running movement.

That is, the last decade, which has seen more and more evidence come out AGAINST shoes, has also seen a shift in the shoe industry.  Gone are the heavy, bulky motion-control shoes, replaced by shoes that are now marketed to simulate barefoot running.  Nike were apparently the first to do this, though I remember Adidas bringing out "feet you wear" in the 1990s.  But it was the Nike Free that was the first "barefoot shoe", and Irene Davis, in her ACSM presentation, told the story that a famous college coach in the USA was responsible for this because he told a Nike rep who had come to watch his team train that his runners were more comfortable being barefoot. 

The rep rushed back to HQ, reported on the athlete's preference, and it heralded the shift.  Now, almost all the companies are focusing on the 'minimalist concept' of shoes.  There are even new companies (Vibram, Newton).  Of course, there are a few stubborn survivors, but the whole market has shifted, there is no doubt about it.  Why?  Because of the current thinking around running, and the role of footstrike, and our feet, in injury risk during running.  So we're all affected, even if we run in shoes, and here's the theory.

The Born to Run theory - our survival was dependent on being endurance running champs

Barefoot running is fascinating because it has made such a big impact in the mainstream.  And a big part of that is the book "Born to Run", by Christopher MacDougall.  It traces the story of the Tarahumara Indians, and contains chapters dealing with the work on barefoot running - Irene Davis and Lieberman have starring roles.

The fundamental premise behind barefoot running is the theory that we are designed for distance.  Lieberman's first big impact on sports science was his research called "Endurance running and the evolution of homo", where he presented the anatomical evidence that humans are the world's best distance runners.  Let's face it, as sprinters, we're pretty lousy.  Even the super fast Usain Bolt runs half the speed of most big mammals for about a quarter of the duration!  Therefore, if our survival as hunter-gatherers depended on our ability to chase and catch prey, we were pretty much doomed by our lack of speed.  That comes about as a result of many factors (I have a colleague doing research into the muscle and metabolic differences between humans and other animals), but that's for another day.

Compounding this is that we didn't have projectile weapons until fairly recently, so we had to catch our prey up close.   But fortunately, our survival didn't depend on our sprinting ability.  What it did require was endurance ability, and that's where we are the champions.

Thermoregulation, endurance success and persistence hunting

Some of the most important reasons we are so good at endurance relate to thermoregulation.  We are bipedal (which makes us slow), but the linearity is good in terms of helping us lose heat and absorb less from solar radiation.  We are small, we have less hair, and most importantly, we can sweat.  This allows us to exercise at fairly high workrates without reaching what is now known to be a critical body temperature that would force fatigue on us.  This is true, incidentally, of animals, who also stop exercise at a very narrow range of temperature.  And animals can't really lose heat WHILE running - they have to pant, which is not possible during exercise.  So running at the same speed, we have a big thermal advantage.

All of this combined leads to the theory of persistence hunting, where humans are able to hunt by outrunning the intended prey over hours, rather than seconds.  There are a few good videos showing this - the hunter selects to hunt at the hottest part of the day, and then identifies the biggest animal and runs after it.  Over seconds, it's a no contest, but the hunter just continues to run, driving the animal out of the shade and into the sun.  This continues for hours, but eventually, physiology wins the day and the animal reaches that critical temperature.  If you have ever seen what happens at this point, you'll know the scene - the animal staggers as if drunk, losing motor control and eventually, it just stops completely, lying down for the hunter to make the kill.

What's the relevance of all of this, you may be wondering?  Well, this leads to the theory of barefoot running, because Lieberman and others argue that humans are designed for distance - it was essential and the "normal" state.  By extension, wearing shoes is "abnormal", and so we must return to what we were intended for - long distance running WITHOUT shoes.  And that's where the evidence comes in!

Shoes and injury

One of the main lines of evidence is actually a lack of evidence.  That is, there is not a single study that has shown that shoes reduce the risk of injury.  In fact, there is now evidence that the risk of injury is unchanged, maybe even higher in the expensive shoes.  Injury rates haven't come down even a little bit since the 1970s, the period which has seen the explosion in the running shoe industry - back in the 70s, the shoes resemble today's minimalist shoes, but about 70% of runners were getting injured, the same rate as today.

There are studies showing that runners who run in the more expensive shoes are more likely to get injured, even when you correct for distance and previous injury history.  There is also evidence that prescribing shoes according to the shape of the foot (high arch gets a neutral shoe, flat foot gets a motion-control shoe) does nothing to the risk of injury in a sample of 2,000 in the military.

So all in all, it doesn't look great for shoes.  There are a couple of confounders in this line of thinking, which I'll address at the end, but the lack of evidence for shoes doesn't hurt the idea that maybe the foot is best, and we should be discarding the shoes and trusting our feet.

The evidence for barefoot running

But what the theory needs is evidence.  And some of that has come from Lieberman, and was published in Nature last year.  He looked at barefoot and shod running with the important realization that familiarity (which may determine "skill") would have an important effect on how their mechanics (and hence impact forces) might be altered. He therefore tested two groups, one which was habitually shod, and another that was accustomed to running barefoot.

Below are some graphs showing the key concepts, and this is really the best evidence for what Lieberman and Davis are saying, so it’s worth explaining carefully (these graphs came up in all three presentations, it is really the only research so far, but it's very compelling).

So the first graph (above) shows the force measured during a single ground contact period in a person who is barefoot and heel-striking. I’ve highlighted the key point on the graph – the impact transient, a spike in the force up to around 2.5 times body weight within the first 50ms of ground contact. That impact transient represents a sudden increase of force, and the rate at which it is applied (which is basically the slope of the line from contact to that peak) as well as the size of that force are associated with injury, in particular stress injuries of the tibia (Irene Davis spoke of this at length in her presentation).

Shoes - spreading the load

The concept of shoes is that they spread that impact out, absorbing some of the force and reducing both the size of the impact transient and also the rate of loading. That’s what the graph below shows. The top panel is the barefoot situation where you land on the heel, as shown above, and the bottom panel shows what shoes do.   I’ll show more data shortly.

 Forefoot running - the body's cushion, removing the transient

The barefoot condition in someone who is forefoot striking is shown next.  Here, the impact transient has disappeared – the forefoot landing allows the impact peak to be absorbed by the calf, ankle and Achilles tendon and the result is a smoother profile, and significantly reduced loading rates and forces.

 The problem - not all barefoot running is equal, and the consequences are extreme

So that’s great news, right? It says that barefoot running is the way to go? In theory. The problem is that making that transition from wearing shoes to running barefoot involves significant risk, and Lieberman's research shows why.  And if you’re not careful, then you actually end up INCREASING the loading rate and the impact force, because you run “badly” without the protective elastic shoe dissipating that force as was shown in that middle graph above.

So below are the two key graphs. First, a graph of impact force in three conditions. Start in the middle – the yellow bar is the impact force running in shoes, while heel-striking, which is what most people do.  In fact, Lieberman found that 100% of people who were accustomed to shoes would land on the heel when they had to run in shoes.  

Now move right – that green bar is the force for people who run barefoot, but who are “good at it”, and have become accustomed to it.  Lieberman found that in this group, the regular barefoot runners, about 90% land either on the forefoot or midfoot.  As explained, their impact forces are significantly lower. 

But those who are not accustomed to running barefoot are the key group, shown in blue.  83% of runners who usually run in shoes would land on their heel even when running barefoot, at least at first.  And shown by the blue bar, their impact force is very slightly higher.

But that’s not the major difference. That comes when you look at the impact transient and the initial rate of loading, shown below.

Now you see that if you run barefoot and are NOT ACCUSTOMED to it, you land on the heel, as shown by the blue bar (again, 83% of his normally shod runners did this).  And the result is an impact loading rate that is SEVEN times greater than running in shoes with the same landing.  If the theory is that this impact transient, and the rate of loading, is related to injury risk, then what this is showing is that people who are accustomed to shoes who then run barefoot (perhaps following unqualified advice in a magazine) are exposing themselves to higher risk of injury as a result of massively increased loading rates.

So that’s the first problem – the purported reduction in injury risk (which is probably real) is dependent on the technique.  If you get it, and land on the forefoot, the impact transient and loading rate are lower (see the green bar above).  But if you get that wrong, the consequences may be severe (further research is required on this).

Learning - skill will improve and mechanics will be adjusted.  But not without risk...

Now, we’re pretty amazing machines, and I can assure you that most people will be able to learn how to run barefoot effectively. That is, with a little practice, they’ll begin to make the adjustments that move them from that high risk group who heel-strike to a more cushioned forefoot strike.

You can experience this for yourself if you take off your shoes and run – within 50m, you’re already starting to make those adjustments, because running barefoot on your heels, well, it hurts.  So we "feel" the ground, more than we want to at first, and over time, we adjust our mechanics and shift to a forefoot landing.  That's why a comfortable majority - 90% - of people who are accustomed to running barefoot will land on the forefoot.

But that brings us to injury risk number two – the adjustments you make to help cushion the landing have consequences. They transfer the impact forces and loading to the posterior muscles, those muscles at the back of the leg. You land with your toes more pointed away from you, and so your calves are contracted, and catching body weight every landing.  You may reduce the impact forces, but those forces that are left are being applied to very specific muscles.  Muscles that may have never been asked to do that kind of work.

The eccentric load on the Achilles tendon and calf muscles is enormous. Your feet and ankles are working much harder, doing what is probably their job, what they are designed for, but they haven’t done it for many years, perhaps a lifetime! The end result is that the strain on the muscle and tendon systems is just enormous, and people break down very quickly.

This is the same outcome as you get from introducing things like Pose and Chi running either too quickly or incorrectly.  Your mindset is "land on the forefoot" and that's a pretty tough skill, and it's a pretty challenging demand to cope with for muscles that have for years not been asked to do it!  My own personal experience reflects this - I was regularly running upwards of an hour in shoes, no pain.  I went running in Vibrams, and did 30 minutes consisting of 1 min jog, 4 minutes walk.  And for three days, I could barely walk, my calves, hamstrings and glutes were so tight - it was typical DOMS from eccentric loading that muscle was unaccustomed to.

I know a few who have experienced the same thing.  And if they overcome the initial stiffness, there is a big risk waiting a week or two down the line, because the constant load on unfamiliar muscles is a huge factor that sees a lot of people get calf or Achilles injuries when trying to run barefoot.

It shows that a) running in shoes requires next to zero eccentric work in those muscles (relative to shoes), and b) when you start barefoot running, you may have to go way back to basics, beyond beginner level, in order to undo what 20 to 50 years of shoes may have caused. 

Making the switch - the practical problem

And herein lies the key - the shift to barefoot running is theoretically sound.  Lieberman and Davis have a compelling case.  But practically, it may be too big an adjustment for some to make.  People have different abilities when it comes to learning a skill, and skill is what it will take to shift out of the shoes.  It also takes different mechanics, possibly muscle strength, and so out of 100 people, it is quite conceivable to me that you'll get a range of responses.

Some will respond brilliantly, and will be able to run big distance barefoot and have no problem.  Some will really battle, and may have to return to beginner level, but they'll learn it.  Eventually.  Whether they have the mindset or willpower and discipline to do it is another question.  Irene Davis presented her recommendation, which started with taking someone up to 30 minutes of barefoot walking, followed by progressive introduction of jogging.  She started at 1 min jog, 9 min walk for 30 minutes.  That eventually worked its way to 9 min jog, 1 min walk.  Which is all good and well, but if you're running 40 to 80 miles per week, the idea of going that far back...not likely.

Then out of our 100 people, I do think there are some who just will not succeed barefoot.  Perhaps they have a structural problem somewhere, perhaps 20 to 40 years of shoes have caused changes that simply cannot be reversed.  Perhaps they have muscle weaknesses elsewhere, and barefoot running is not sufficient to overcome those.  One of the problems I have in this debate is that those who are advocating barefoot running are basically treating it as medicine (if you have a condition, take a drug.  If you have an injury, take barefoot running...).  The problem is that this is not done with any idea of dosage, "contra-indications" or exclusion criteria, and some might just not be able to do it, which makes 'one-size fits all' advice unhelpful.

The point is that there should never to a single approach to an injury problem.  I think there's no doubt that someone who is chronically injured may have their best chance in trying barefoot running.  But this cannot come at the expense of a holistic view (and I must emphasize, Davis is not guilty of this), and so I'd put barefoot running forward as part of a solution, something to try, and if you are one who succeeds, then go with it.  But if not, then look elsewhere, and don't worry, it's not as simple as some are suggesting.

High performing runners - barefoot may just not be practical

The other group that I have to mention is high-performing runners.  Not necessarily only the elite, but even those who train for a fast marathon, or Ironman, or even high mileage 10km runners.  They are doing 120 to 200 km per week, and a lot of it is fast running.  Much faster than persistence hunting would have required - obviously, there is no data, but it's unlikely that humans have ever tried to cover 200km in a week, a lot of it at 7 min/mile or faster, even getting down under 5 minutes/mile for long periods.

If you are doing this kind of distance, then there is a real question over barefoot running.  Some will argue that the reduction in loading rates and impact transients makes it more likely that you can succeed barefoot, especially at high mileage.  But there's a confounder here too - muscle fatigue.  The third presentation in the symposium showed some really interesting evidence that the loading on the joints and bones was HIGHER as muscles fatigued.  This stands to reason, of course - muscle absorbs much of the impact force, and so tired muscle loses that ability, exposing the joints.

So those who are training for performance may struggle because of a muscle fatigue issue - the muscle is working differently, and harder in certain muscles, when barefoot, and that may be limiting.

The bottom line - individualized approach, but sound theory

On the whole, barefoot running, or at least minimalist shoes, is a sound concept. Lieberman’s theories regarding our ability to run are solid, and I do believe that the days of bulky, motion-control shoes are numbered. I think that barefoot running will be very difficult to implement, if not impossible, for some people and probably doesn’t work in the extremist view that some people are offering for it.

I believe that it may be PART of the solution for SOME of the cases of injury. For SOME, it may be ALL of the solution, the solve-all. For others, it will be completely ineffective, and for other still, it will be the cause of their problems.

Recommendations

So if I had to give some recommendations, speaking now both as a scientist and a coach:

• If you are are injured, or struggle with chronic injury problems, then give barefoot running a try.  It may be especially helpful if you have knee problems, or any anterior injuries (anterior shin pain, for example), because going barefoot will switch the load. 
  
  The benefit (in a backward kind of way) of starting injured is that you're pretty much compelled to go back to beginner level and build up, so your chances of staying beneath that "injury risk line" are better!
  
  
• If you are not injured, but fancy trying it, then by all means, go for it, but be very careful.  I would suggest the best way to approach it is to think of barefoot running as a training modality.  Just like you'd go to Pilates to improve core strength, or spend time in the gym on upper body or leg, think of barefoot running as a session. 
  
  There is some evidence for this, incidentally.  Pieter Bruggemann (of Oscar Pistorius testing fame) actually did a study on the Nike Frees, and found that just using them in the warm-up improved lower leg strength, balance and agility within five months.  So this points out one way to do it - do warm-ups either barefoot or in minimalist shoes.  Or do five minutes at a time, building very, very slowly, so that you don't affect your other training but gradually develop the strength.  If you find that you enjoy it and don't seem likely to be injured, then push on.
  
  
• If you are a high-mileage runner, then think carefully about tinkering with barefoot running, or about changing your technique to land on the forefoot.  For one thing, if you are a competitive runner, or even aspiring runner (going for PBs, that is), then you're the person most likely to overdo it!  It's part of what makes you competitive!  So again, I'd advise that you consider incorporating barefoot running into the programme as a training aid, because it will help your feet, calves and ankles.  But as with any training aid, phase it in very slowly.
  
  
• If you are constantly battling calf, hamstring, foot or ankle problems, then consider barefoot as treatment, but take the most conservative guideline you can think of and halve it - do 50% less than what that says.  The rationale is that someone with a hamstring injury can't just avoid strengthening the muscle - it's part of the rehab.  So for chronic calf and ankle/achilles problems, running barefoot may be exactly what you need.  But you are the kind of runner who has to start with five minutes of walking, not running, and hold back massively.  If you can succeed, then hopefully this will help your return to running in shoes, and maybe, eventually, minimalist shoes.

Then, no matter which category you fall into, golden rule - try not to control your landing.  You shouldn't be thinking about how your foot hits the ground.  Just "listen" and "feel" the contact, and your body will gradually adapt it for you.  The mistake that is made is to think "forefoot" and this leads to excessive loading, as explained above.  You will occasionally land on the heel, but the natural response is to cushion the landing.  The danger is trying to catch the landing, so just relax and focus on not reaching, not pointing, not catching.

Conclusion

And I’d end my opinion on barefoot shoes by just cautioning its advocates to avoid making the same mistake you are accusing the shoe industry of having made for many years. The shoe industry, it is said (with good reason) advocated for many years that shoes were the “answer” – one size fits all (pardon the pun), and that simply putting someone in the right shoe would prevent or cure injury. Now, the barefoot movement is in danger of making the same error – learn from the past and recognize that individuals need individual solutions. So don’t put everyone in a barefoot box.

Ross

P.S.  A footnote...(pardon the pun)

The devil's advocate view

Just to end, I want to point out three counter-arguments to three arguments made by Dan Lieberman in his talk.  Mostly, this is to give you some ammunition when you get overwhelmed by a barefoot advocate who is arguing it as the sole solution, the be-all, end-all of running.  It's likely far more complex, and here are some responses...

1.  Shoes are abnormal, barefoot running is normal

Lieberman said this often often in his talk.  He says that when we see a guy running barefoot, maybe we should think of him as normal and ourselves as abnormal.  And it may well be true.  But the problem is that "normal" doesn't imply good, and "abnormal" is not necessarily bad.  Think back 100 years, life expectancy was about 50.  Go back another 50 years, and you expected to live to your 40s!  People died young all the time, particularly mothers during childbirth.  Today, it's up near 80 in a lot of countries.  You might say that in 1911, you were abnormal if you lived to 80.  Today you'd be normal.  Is "normal" wrong, or just different?  It tells nothing of what is good or bad.  Sometimes "normal" changes as part of progress.

The key is that in this case, normal is meant to convey that our feet should be doing what they're designed for.  And that may be true, but it's still short on evidence.  We can't discard things that are "abnormal" just because they're unnatural...

2.  Our ancestors were great runners, and being barefoot is the reason

This is key to the debate, because it is being suggested that hunter-gatherers, minus the state of the art shoes, were great runners.  And therefore, the lack of shoes is the reason.

So two things.  First, I'm not necessarily convinced that all of them were great runners.  Let's take a group of 100 people today.  There may be 50 who can run at a reasonable level - the finish marathons, half marathons, in the top half of the field.  They get injured maybe once every two years, but if they're good about training (strength work especially), they keep going.  30 of our runners might really struggle.  The do 5 hour marathons, get injured often, but can get through on isolated occasions.  10 might be absolutely incapable of running - they get injured in the warm-up and just cannot finish 5km, let alone marathons.  And 10 are the best runners.  One of them is Ryan Hall, an elite.  Nine are good, competitive runners.  They push the limits and get injured, but recover well, and they are the "runners".

Now apply this to the Kalahari, or the Tarahumara.  Is it not possible that in a village of 100, there are 10 "runners" who are the best, 50 others who are good enough, and that they provide the running for the community.  Maybe there are 40 of those 100 who just suck at running!  They become artisans, doing the building or hut construction, maybe they become fishermen!  But they can't run.  I simply do not know the answer to this one - I don't know, for example, whether 70% of Kalahari hunters get injured every year.  Maybe 2 in 3 Tarahumara get injured, take a few weeks off, and then return to running.  Not knowing this means I'm less convinced by the argument that being barefoot is better.

Then the next point - why is it that we've identified being barefoot as the key difference between us and our ancestors?  We look at them, and we say they were great runners who rarely got injured (a point I'd question, as explained above).  Then we make the next deduction, and we say "they didn't wear shoes, that must be why".

Well, I can think of plenty of reasons why they may have been injured.  For one, they didn't sit at a desk 9 hours a day.  They didn't have Playstation and TV and computers.  I mean, I've been sitting down for 90 minutes typing this - my posture and core muscles have been asleep.  But that wasn't true for Kalahari - they climbed trees, slept on uneven surfaces, walked, were physically active.  All of this may lead to improved strength, especially in the stabilizers - the core and glutes.

That may well be as much a reason for their apparent ability without injury, and barefoot running may only be part of it.

3.  Injury rates haven't changed, so the shoes clearly don't work.

The argument here is that injury rates were 70% in the 70s and 70% in the 2000s.  So, despite shoe technology, which is hugely different, we still get injured just as much.  And sure, this is true, and when viewed together with the other evidence about shoes, I think it's a good case.

But just remember that the people who are running in the 2000s are not necessarily the same as those running in the 70s.  When I think of running in the 70s, I think of Amby Burfoot - small, wiry, probably ultra-economical (sorry Amby!  Thanks for reading!).

When I think of running in 2011, I think of Oprah Winfrey... sorry Oprah.  Simply, the people who run marathons today are not the same kind of runner.  They are heavier, slower, and probably do less training but then still run the marathon distance.  When viewed this way, it's perhaps not surprising that 70% are getting injured.  If anything, it suggests that shoes may be helping, because many of the runners of 2011 are walking/jogging/running injury risks!

So if you're going to attack the shoes, then I'd rather do it on the basis of the evidence that they don't change mechanics/pronation, that they don't alter risk in controlled studies, not because of this historical comparison!

That's all folks.  I know it's a lengthy piece, thanks for reading.  It really is just an overview (this is the summary!).  For more on this, check out the featured series on running technique and shoes here!  I discuss a bit more of that evidence on shoes, which I just touched on in this post.

Ross

PPS:  Thank you for all the comments in the discussion below.  I will do my best to respond, but bear with me if it takes some time!

Barefoot running - the safe neutral ground

Barefoot running:  Finding the neutral view in a lively discussion

Thanks to everyone for the lively discussion on the previous post on the recent observation (not scientific study!) on a rise in the number of injuries associated with barefoot running.  It certainly stimulated much more debate than I could keep up with, especially while traveling back from the UK.

I know we've received many, many comments in response, and many readers don't read those comments (though if you have some time, there are some good views), so I felt I'd try to wrap up the barefoot post with a final word of my own (I am 100% sure that this topic will come up again in the future, so don't worry)

A debate where the prudent approach is the only one...for now

It strikes me that of the many issues in sports science, this is the one where taking the neutral, fence-sitting position is really the only option until proven otherwise.

Those who follow the site will know that I'm not usually a "fence-sitter" and I don't need much encouragement to throw out the clear and unambiguous opinions - for example, Caster Semenya shouldn't run against women, Oscar Pistorius has an advantage, dehydration doesn't cause cramp, South African sports administrators are mostly corrupt or incompetent.

But on this one, I just don't can't commit to such an extreme view, either way.  And reading through all the debate in the last few days does little to convince me otherwise.  We've heard many testimonies about people who have switched to barefoot or minimalist shoes with great success.  Well done, and good for you!  If it has solved your injury problems, or opened up a world of running to YOU, then long may it continue!

But occasionally, we hear from someone who tried and failed and wishes they'd never discovered barefoot running.  I maintain that this latter group is in the minority - most people who try it out, fail, and get injured, will go back to shoes and keep running, sometimes injured, sometimes well.  These people, I suspect, don't often share their views, and certainly not as passionately as those who have succeeded, in large part because the blame for "failure" is often placed at the feet (yes, I know, sorry) of the person who has just failed!  Seriously, who wants to own up to failing at the transition when dozens will simply say "You didn't do it right"?  Not as many as will share success stories, that's for sure.

And yes, I hear you on the possibility that these "failed" conversions have erred in their training.  It is a very valid point, one which I think may be true in many of the cases.  But not all.  At least, not until you can prove it to me!   And herein lies the crux.

Testimonies that should be heeded

The point is that guys like Matt have tried barefoot running.  They're not simply dismissing it out of hand.  And I know Matt, and respect him highly, and he's a guy who is really open to innovation.  When we wrote our book together, we actually argued on certain areas where I was being more "conservative" than he was with regards to training techniques!  He is someone who will not approach the issue in a closed-minded manner, as his books have demonstrated.  He has shown a willingness to learn, to dismiss "dogma" and to challenge beliefs, and those who are being very critical of his views (and ours) should bear this in mind.

So his views, while more extreme than my own on this topic, should be heard, because if you're a barefoot supporter, and someone has tried everything, right from running 1 MINUTE a day barefoot to train gradually, and still failed (and they're also in the top 5% of runners, I might add, not 120kg back-of-the-pack 6 hour marathon runners), then we all need to take heed.

Failure to do so is not only reckless to all those who are hanging on this barefoot movement as the solution, it's presumptuous to those who have tried and failed.

My thought is that if someone is injured, then it's likely their training is at fault, regardless of what they have on their feet.  There are some for whom a switch to barefoot will change training and mechanics (especially the knees, as we've had pointed out, thank you to those who've brought it up).  There are others for whom it will initiate a lifelong series of problems, potentially putting an end to running as they know it.

And that alone makes me cautious.  I'd be very hesitant to commit one way or the other.  And so personal testimonies are very welcome, but to apply a testimony of one (or even a group) to many, that leaves a lot of room for catastrophe!

Thanks again for all the comments, great discussion!

Forthcoming attraction - the FIFA 2010 Football World Cup in SA, and the Science of Football

So I mentioned earlier that I've just arrived back from the UK, in what was ultimately a disappointing end to the Sevens Season.  If I had a blog devoted to the sport of rugby, and if I had a following mostly in South Africa, I would fill a month of reading with the reasons and the issues facing the sport.  But alas, I don't.

I do however know that the biggest single sports event in the world is now imminent here in South Africa.  From arrival at the airport, all the way to my home, the signs for the FIFA 2010 World Cup are everywhere.  The news has been dominated by the build-up, and it promises to be a magical four weeks.

And there will be no better opportunity than this to look at the Science of Football in the coming weeks.  The physiology, performance analysis, altitude, aerodynamics, crowd support and penalty shoot-out dilemmas faced by teams should make for some great discussion.

So look out for that!

Thanks once again!

Ross

Barefoot running and injuries

Barefoot running - it was a stimulus plan for physical therapists after all

About four months ago, we did a lengthy series on barefoot running, which began with this post on the latest research from the Harvard lab looking at how habitual barefoot runners' mechanics different from shod runners'.  That was followed up by a six-part series, done in Q & A format, where we looked at the evidence for barefoot running as a means to prevent injury.

In that very first post, looking at the Harvard study, we made mention of barefoot running being a "stimulus plan for physical therapists".  This was entirely predictable, because the media jumped all over the Harvard study and reported it as "proof" that running barefoot was less likely to cause injury as a result of the lower impact forces it caused.  This was despite the paper actually reminding people that it had NOT shown this at all.  Its final sentence was "controlled prospective studies are needed to test the hypothesis that individuals who do not predominantly RFS either barefoot or in minimal footwear, as the foot apparently evolved to do, have reduced injury rates". 

This research came along into a "market" that was increasingly moving towards barefoot running.  The book "Born to Run" described the feats (pardon the pun) of a tribe of Mexican Indians, and gave legs to the movement that was picking up followers all over the world.  Barefoot was suddenly the way of the future.  It inspired our series, and much debate on the issue.  All the while though, people were trying to advocate caution, warning that simply going from shoes to barefoot would guarantee injury.

Increased injury rates - the stimulus plan is working

It should come as no surprise that medical doctors and physical therapists are now beginning to pick up on a potential fall-out from the "Born to Run" movement.  Our friend (and book co-author) Matt Fitzgerald has hunted a few down, and his report details of a sudden increase in injuries caused by barefoot running. According to those he interviewed, the nature and number of injuries has changed in recent times.

There is however a missing piece of the puzzle here.  First, the increase in the number of people running barefoot would produce more barefoot injuries even if the relative risk was the same.  Imagine that in a community, 100 people run, 80 of them in shoes and 20 of them barefoot.  If the injury rate is equal for both at 10%, therapists will treat 10 patients, 8 who run in shoes, 2 who run barefoot. 

But if a book or research studies plus the media inspires 40 people to switch to barefoot running rather than shoes, the split would now be 40 in shoes, 60 barefoot.  Now, even if the injury risk stayed the same, they'd suddenly treat fewer injuries from shod runners (4) and more from barefoot runners (6).  Has barefoot running caused more injuries?  Or has running caused the same injury rate, regardless of what is on the foot?  That's why properly controlled prospective studies are still needed. 

However, one of the doctors who Matt interviews is still of the opinion that the barefoot running is responsible for specific injuries.  He explains how plantar fasciitis injuries are on the rise, and attributes this not to overuse, but to barefoot running.  He also pins down why those who swtich to barefoot running often don't report injury.  His words: “There are a fair amount of people who have tried it but have stopped pretty quick, just because they realized that it was not going to work for them,” he says.

The spike in injuries - the stimulus plan

The potential spike in injuries is similar to that which I once saw reported as a result of Pose.  I recall reading how therapists always saw increased patient numbers about two weeks after a Pose running course had been held in the city.  Runners, armed with a new, injury-preventing running technique, were going away to implement what they had learned without due caution, and breaking down at either the calf, foot or Achilles tendons.

The same will happen for barefoot running, unless the runner is a) very, very careful to manage the transition slowly, and b) mechanically able to do it.

I raise point b) because this is something we don't fully understand yet, but I am convinced that there are individuals who simply cannot get away with barefoot running.  I may yet be shown to be incorrect, but only evidence will convince me of this, not the anecdotes of the few who are successful at making the transition.  Those who fail rarely speak out - they just switch back to shoes.  Those who are successful tend to be vocal, and I believe this is why the risk has been under-recognized.

Having said all this, I don't believe that barefoot running is without its merits.  And please, before I get slated for selling out to shoe-companies, take some time to read the series we did on barefoot running (especially Part 5).  I know it's long, but it lays out all the thoughts, and ultimately concludes that there is merit, but that caution must be used, and if you advocate that barefoot is the only way to go, you're making the same 'extremist' error that shoe-companies are being accused of making.  I don't want to rehash all the same arguments again - they're in that series. 

Conclusion - universal truth doesn't exist

But bottom line - don't buy into the hype.  Try it out, with caution.  See if you enjoy it (it is a lot of fun), see if you feel different and then build it slowly into the programme. But if it doesn't work, don't believe the 'criticisms' that it's your fault.  I've heard these re both Pose and barefoot running - if you run Pose and get injured, you may be told that it's because you've failed to do it right.  If you run barefoot with injury, you will be told that it you haven't made the transition gradual enough, or that you're landing with a stiff ankle, or pointing your toes, or some variation which ultimately boils down to "It's you, not the concept".

It is not true.  It may just be that you cannot do it.  One-size-fits-all fits exactly no-one.  So rise above the generalization and hype!

Ross

Barefoot running and shoes Part 5

Barefoot running and shoes - the Q & A Part 5

This is the final installment of the Q & A on barefoot running vs shoes.  I'm sure next week will bring further discussion and probably a post or two on unanswered questions, but the interview done earlier this year with Run2Day is at an end.  A short post today, and some practical applications, which are my suggestion for how barefoot running would be introduced into running to avoid the very likely overload on the calves and Achilles tendons early on.

What's struck me most in this discussion, apart from that it's so passionately debated (which we knew before the series began) is how large the range of approaches to the subject is.  There are biomechanical angles, historical angles (the Roman army features as protagonists), anthropological angles, economic perspectives, evolutionary arguments, and so on.  Many of which support running barefoot, many which do not.  So thank you for educating me on those topics.

I think it's safe to say that there is no obvious answer, as is the case for many questions.  But it's an intriguing debate, and it will be interesting to track how the 'movement' progresses in the next few years.  What would be really cool, for example, would be to track the sale of Vibrams across the US to see how the consumer responds to all this information, because the surest test  of whether it works will be resale of Vibrams - if people buy the third and fourth pair, then they've converted.

Anyway, here goes with the final few questions.

14. Do you have any news on innovations or research related to this subject which you’d like to share with us?

Not so much an innovation, but a concept that I think is also important for understanding why running barefoot might reduce injury risk. We have heard so often in this series, and elsewhere, that people who switch to barefoot running find that they can run injury free. We look at biomechanics as the explanation for this, when in fact the more simple answer is right in front of us.

That is, if you run barefoot, your training volume is limited by what your feet allow you to do. For example, if you take two runners, equally untrained and with equal risk of injury, and you give one of them a pair of shoes and the other runs barefoot, I guarantee you that the barefoot runner will do LESS training in the first month than the runner in shoes. Why? Because his feet will hurt, his calves will be much stiffer, his ankles will hurt, and his distances, which he can select for himself, will be cut down substantially.

The runner in shoes, on the other hand, has only a stiffness barrier to overcome. He is stiff for a day or two after this first run, but that soon disappears, and then he can increase the distance without restraint. Pretty soon, he’s doing 4 or 5 runs a week, total of 50 km a week, which may be too much, too soon. His barefoot companion, however, has been forced to increase much more gradually. He also gravitates towards softer surfaces, offering more variety in landing type.

The guy likely to get injured in the above scenario is the shod runner. And so when you read testimonies from people who have thrown away their shoes and run barefoot and they proclaim that being barefoot has cured all their injury concerns, you need to ask very seriously – was it being barefoot that sorted out their injury, or did being barefoot alter their training, which sorted out their injuries?

This is why the only “perfect” study that will prove (to me, anyway), the benefit of running barefoot, is a study that forms three groups. All runners must have identical histories, demographics, injury risks (there goes the study right away, of course. But within reason, this is doable). Group 1 gets shoes and chooses their own training volumes. Group 2 runs barefoot and chooses their own training based on feedback and their perceptions around pain and recovery. Group 3 is in shoes, but they run according to a very conservative programme, which increases their distance by about the same amount as the barefoot group would select by themselves. This controls for self-selected increases in workrate.

In the short term, the rates will not be different. Yes, there is a long-term consideration and that is why this study would have to continue for at least a year, probably more. I honestly don’t know what would be found if this is done. But to address the common perception that being barefoot is a ‘cure’ for injuries, you have to question whether it’s a consequence of the impact on training volume.

I cannot stress enough that the reason for injury is training, which brings us full circle and back to the study of van Gent. Shoes, running technique and so forth are factors, yes, but the only factor that is KNOWN to cause injury is training too long, too hard, too soon (or combinations of the three). And so when you approach this debate on shoes vs barefoot and injuries, it’s vital to bear this in mind – training is key and any runner who trains at the right level for their history and circumstances (this is where strength, flexibility, stability come into it), will not get injured.

15. With all research in mind, what would you opt for: choosing either barefoot or padded running (for maximum adaptation to one style) or choosing a mixed training (to keep the body alert to changes and train different groups of muscles)?

Mixed training, without a doubt. Again, hypothetically speaking, if you took a group of runners and you attempted to put them all on a barefoot programme, I would put forward that a third of them will pick up a limiting injury within 3 weeks. A calf or Achilles injury, most probably. They’ve probably overdone the limit and trained too much, of course, but their failure is a training one, and it’s for this reason that Daniel Lieberman, and others are trying so hard to advocate a prudent approach to training.

The irony is that even podiatrists are not against the idea of barefoot running. At least, not the ones I know of. But they’re just adopting a cautious approach, in the absence of evidence to the contrary, and they recognize that one approach does not fit all.

However, if the return to barefoot is managed very carefully, with short distances, and infrequent runs, then it would be possible to see positive outcomes. And I’d even say this is desirable. Barefoot running does affect running mechanics, and I believe it affects them positively. It’s also a lot of fun – I’ve got two pairs of Vibrams and I run in them once a week and it’s really very enjoyable, a different feeling and a stimulating way to train. Having started out with slow, and very short running, I’ve been able to build the distance to the point where I can finish normal sessions. But it’s been 6 months and my soleus muscle still hurts the day or two afterwards, and I can’t imagine being more conservative with how I’ve increased the volume of training. Therefore, I view barefoot running as a training tool, with mechanical and muscular benefits, but I can’t, at this stage, see the feasibility of going all the way to half marathons in Vibrams. Lightweight shoes, yes, but not all the way. And that’s fine, just as it is for a few other runners who I’ve advised on the same thing.

In terms of applying this to training, conservative is key. My advice would be that if you’re keen on barefoot running, you limit it to once a week at first, and you limit the length of each run to 50% of your normal distance, and you break it up into intervals of about 5% with walking between.

For example, if your average run is 60 minutes, then my advice is that you head out for 30 minutes, but that you run for 2 minutes, walk for 1 minute, 10 times. At least for the first few week or two, and then gradually increase the running from there, if you feel your feet, ankle and calves are up to it.

16. Conclusion: Barefoot running/Natural Running: Religion or Ratio?   

Ratio, given those two options. The neutral view is likely the best and most accurate one in this particular debate. The shoe industry made the error of positioning itself as the “solve-all” for runners when it said that it would reduce injury risk. I wasn’t around at the time, but I’d be willing to be that in the 1990s, if you didn’t have the latest gadget or gizmo on your shoe, along with rather large cushioning, your running was doomed to failure…We’ve looked at evidence to the contrary in the last few posts. So I think it’s important not make the same error now and dismiss out of hand what many runners have succeeded with.

It’s very easy to point to high injury risks of runners (60 to 70%) and say that shoes don’t help these runners. But there’s no control group, and one might equally argue that it’s incredible that the injury rate is not higher than 70%. As I said yesterday, we are a desk-bound society, which is inactive as children and which takes to a 60 minute a day run on unforgiving surfaces as though we expect our bodies to handle it. We carry with us years of “neglect” and weakness is stabilizing muscle groups, and we pay little attention to training strength. We also recklessly increase training volume, and yet are surprised when we pick up injuries (I myself am just as guilty of this!). And then we find the culprit – the shoe!

Balance is key. There are people who may not be able to run barefoot, however slowly they increase their volumes. There are people who find that they can. Perhaps some day everyone will be running barefoot or in lightweight shoes, who knows? But right now, with the sum of the available evidence, I’m happy to say that barefoot running is a great way to train, it’s different and stimulating and offers many mechanical benefits, but like most things, generalizing will wrongly influence too many people for it to be dogma.

Looking ahead

As I said, next week will probably see some more discussion on the topic.  I'm in Hong Kong for the next Sevens tournament, maybe it's time to do a little bit of rugby science posting to pass the last week of the tour.  And the marathon season is slowly approaching, which promises to provide a lot of discussion and interesting analysis, so that's something to look forward to!

Ross

Barefoot running and shoes Part 4

Barefoot running and shoes - the Q & A Part 4

Thanks to everyone for the discussion around the previous post.  I've really enjoyed the debate.  I must make the point that any views here are obviously opinion.  Why?  Because there's no conclusive evidence that putting a runner who has run in shoes for 20 years into either lightweight shoes, Vibrams, or barefoot, will reduce their risk of injury.  Until someone produces that prospective, well-controlled study over a long period, anyone's "answer" in this debate is going to be opinion.  Yes, there is a lot of evidence against shoes, but that's because science seeks to disprove the current hypothesis, and little has been done to show up problems with barefoot running - it's too soon. 

And what we've seen so far is the running shoe equivalent of the "shark attack" phenomenon, where the occurrence of an event is greatly inflated by a reporting bias (shark attacks are exceedingly rare, yet we are all terrified of them, because the media coverage given to them is disproportionately high).  Similarly, I really do believe that there is bias in barefoot running reporting, because the people who come forth with their stories are those who have succeeded.  No one has yet documented the failure rate - people who have abandoned the barefoot campaign.  And yes, these people are likely to have failed because they made an error in increasing their volume or intensity too rapidly, but equally, those who get injured in shoes can be accused of the same thing (van Gent, 2007).

As this series progresses, I'll move towards stating what I would recommend as as a practical approach to barefoot running, based on the evidence like that discussed yesterday, and which will be described more today, as well my own experience and work with runners.  But the best part of being able to discuss this topic is to share in those opinions - as is typical though, when people disagree with them, they tend to take out the "you're losing objectivity" club.

Today's post delves a little more into the shoe evidence, looking particularly at the "intelligence" of the body with and without shoes.  Then I end off with some discussion around the whole argument that our ancestors and the Tarahumara Indians run barefoot, and therefore so should we.

Again, in isolation, this post will be strong theoretical evidence for barefoot running, which I hope most have gathered is a recurring theme.  I'm actually very positive about barefoot running and the role it can play in every runner's training and development.  I'm just trying to maintain some balance, lest the movement become, in the words of a respected colleague, "a stimulus plan for physical therapists and podiatrists"!  And believe me, they've made a good few new patients as a result of over-zealous implementation!  Here goes, with questions 10 to 13.

10. There is research (Robbins and Gouw 1991) that says that running with cushioned shoes leads to the fact that the perceived impact on the body is lower than the actual impact (or: our body is fooled by the cushioning). How do you interpret this research?

This body of research is extremely interesting. It’s been borne out by a number of studies which have looked at impact, soft tissue vibration and muscle activation. Benno Nigg has proposed “muscle-tuning” where the degree of muscle activation, especially pre-activation (which is the muscle activity immediately before the foot strikes the ground) is adjusted depending on the impact conditions in order to defend the soft tissue vibration (Boyer & Nigg, 2007). In other words, the body is “smart” enough to anticipate the impact conditions, and whether the cushioning exists and then it regulates impact and vibration by adjusting muscle activation. The simple analogy is that if you stand up on your office chair and jump off it, you can land extremely hard if you just let gravity work on your ‘dead weight’, or you can cushion your landing through anticipation of the impact and the correct muscle activity. That’s what the body is doing in mid-flight, which is quite remarkable.

Whether the perception of impact is important or not, I’m not convinced either way. Let’s say that you run in a highly cushioned shoe, and you perceive the impact to be much lower than it actually is. So what?  Some would say this is a favourable outcome, because any time you can perceive less impact, it’s good. What Nigg is proposing with muscle-tuning concept is that the forces and the vibration of the soft tissue are being regulated. So perception is not reality, in this case. And the impact forces may not be higher – studies seem to disagree on this particular aspect. So I certainly believe that the perception is altered, but I don’t necessarily agree that the body is being “fooled” by this – the perception is being fooled, yes, but the brain and the muscles may be managing it quite appropriately!

What is significant, and this is a strong argument for why bulky shoes do have a negative effect, is that the ability to “feel or sense” the ground may be altered by shoes. Sensory information from the foot, which tells the brain of underfoot conditions, surface hardness, slopes, objects, is certainly altered by shoes, and this may affect the timing of muscle activity, as well as the degree, particularly towards the end of races, when fatigue is a factor.

Incidentally, the same scientists did a really interesting study a few years later, in 1997, where they made people step onto a material that was the same as is used in the midsole of running shoes (Robbins & Waked, 1997). They did this a number of times, but the difference was that they were either told that the material was a state-of-the-art cushion, with all the latest technology to minimize injury (they even drew graphs and made up fake endorsements from athletes), or they were warned that it was the same as the material used in cheap shoes, responsible for many injuries. This is the WARNING trial shown in the graph below. Effectively, they were evaluating how belief about cushioning affected impact.

It turned out that when subjects thought they were landing on the soft, high-tech material (Deceptive trial), the impact forces were actually HIGHER than in the Warning trial when they expected the cheap and ineffective material. And barefoot had the lowest impact forces of all. The other amazing finding, as is shown in the graph above, is that in the barefoot and cheap material trials, the impact forces get lower and lower as the subjects repeat the step, which shows a learning effect that is not present in the ‘Deceptive’ trial where subjects thought they were landing on a soft material. So this is remarkable – it shows how an expectation of impact can actually alter impact, and again, it supports what Benno Nigg and others are saying about anticipation of impact, with the ability to adjust muscle activity to defend some other variable.

This is why it’s possible to run barefoot – the body is a remarkable machine, able to make in-flight adjustments to provide the optimal landing, and this is a strong argument for why being barefoot might give some advantages. At the very least, when people stare in wide-eyed horror at those who run in either light-weight shoes, or Vibrams, or bare-foot, because “you’re running without essential cushioning”, they’re reacting to a misperception – the body can provide cushioning.  And there is evidence for this - from Daniel Lieberman's latest study, from Nature.  We looked at this in a little more detail recently, but the graph below shows one of many interesting findings.

Here, the impact forces are shown for three groups:  First, on the far left, are runners who normally wear shoes, running barefoot. In the middle, runners who are wearing shoes, and on the far right in the shaded box, habitually barefoot runners, who strike forefoot.  Clearly, the impact force is reduced in the forefoot strikers when barefoot. 

However, there's a catch to this whole argument.  The danger is that in order to provide this cushioning, muscles are working harder.  In my answers to an earlier question (Q 4, in Part 2 of the series), we looked at some of the changes in running patterns when barefoot.  The knee is more flexed, the ankle more plantar-flexed, and the landing point more at the forefoot.  These changes are responsible for helping with the cushioning, but mean greater load on the calves (particularly the soleus muscle) and Achilles tendon, which rises substantially, and now you can see why this is happening – it cushions the landing very effectively. When this cushioning response is used, those muscles and tendons are taking enormous strain, and if they are not adapted or eased in, they break down. So again, we have a situation where theoretically, there’s a lot to be said for barefoot/minimal cushioning, because it allows the body to do what it does best. But there’s a real danger there too, which has to be acknowledged, and then managed very carefully.

11. One of the claims of barefoot runners is that most of the modern shoes (which have serious heel cushioning) take away essential sensory information while the barefoot runners' body uses the rich sensory information the foot provides. Nike Free’s, Vibram Five Fingers also work in the sense that they do not ‘disconnect’ the sensory input of the foot. Is that a valid argument? If so, what are the benefits?

Yes, and I think this is a strong argument for barefoot running. Whether the sensory “barrier” still exists in minimalist shoes, I’m not sure. The advocates for barefoot running say that the shoes, no matter how similar to barefoot running, do affect sensory feedback. My experience is also that they do, but not nearly as much as a normal cushioned or stability shoe. The Vibrams in particular feel remarkably similar to barefoot running – studies suggest that the mechanics are the same, and the sensory feedback is as near to barefoot as is possible – it’ll never be the same, because there’s a 4 mm barrier between the foot and the ground. But it’s close, and this may have beneficial effects. Again, that’s never been proven – it is a theoretical position only, but it does offer a potential upside to barefoot/minimal shoe running.

12. Another claim is that modern shoes are considered to act like corsets: they give support but also make the muscles lazy and therefore weaker. Is there any proof that this statement is correct?

The study we looked at yesterday, by D'Aout, showed how chronic shoe use changes the morphology and biomechanical function of the foot.  So it's certainly true that way.  Also, if you go out and run barefoot, even for a short time, you’ll discover muscles in the foot and calf that you had long ago forgotten you had! The stiffness and some of the muscle sensations you feel when you run barefoot is completely unexpected – this suggests that running in shoes involves very little work from those muscles. So from that point of view, it’s easy to say that, yes, running in shoes does reduce the work done by certain muscles of the foot.

However, to extend that position and say that this increases the risk of injury while in shoes is a stretch for which I don’t believe there is proof yet.  What this evidence does is explain why it's so difficult to run barefoot when you've been in shoes for a long time, but I don't think it translates the other way.  Similarly, if one runs barefoot and these muscles are developed, will it reduce the risk of injury when you then run in shoes? It sounds reasonable, certainly, but it could equally be true that when you wear shoes, those muscles do not need to work and therefore can be weaker.

The analogy is that you can become wastefully strong, and we tend to balk at the idea that we can “afford to be weak”, but it all comes back to what is required in order to do a specific task – a marathon runner, for example, may not have a strong upper body, but training the arms and improving their strength by 50% doesn’t produce a faster runner. So is it possible that shoes have created a situation where the work required of the foot is reduced, and this is acceptable, provided the runner continues to be in shoes? Again, no one has really provided proof to answer these questions.

However, I believe that barefoot running offers the potential to help improve foot strength, which may reduce injury risk, if it is managed correctly. A number of coaches, for example, will have athletes to a small amount of running barefoot, and I think that is reasonable, even recommendable, because it helps with the strength of these muscles. Overdo the barefoot running early and you’re headed for disaster, however, as I said previously.

13. Then there is the antropological view: we ran for millions of years on our bare feet; our bodies are not made for walking on running on shoes which have a heightened heel (ranging from high heels to air in sneakers). Do you agree?

I’ve heard this position, and while I can see the merit to the thinking, I think it’s probably the weakest argument for why we should run barefoot, for a couple of reasons:

First, the conditions under which we run today could not be more different than they were millions of years ago. The hardness of running surfaces has changed, the terrain is completely different, and even the way we run is different – a structured 60 minute training is vastly different to a 8 hour migration or hunt that may involve walking, climbing, crawling and resting.

Second, we are different. I’m no anthropologist, but I’d like to see a profile of what the individuals looked like in these “endurance runner” communities. Were some of them 100kg or heavier?  Did they all have a natural inclination for running? In a village of say 100 people, did 100 of them run successfully in order to hunt? Or was the hunting and locomotion done by 20 out of the 100, with the others doing other things that perhaps did not involve such a great deal of endurance work – perhaps some were fishermen, while others hunted? Just as today, if you took 100 people at your running club, you might find 5 great runners, 25 good runners, 50 average runners and 20 non-runners, there’s no guarantee that our ancestors all run well (please note that I'm illustrating a principle here, so please don't attack the numbers...). Unless I’m missing something? So perhaps it’s possible we are comparing those hunters, the “elite runners” of those communities, to our struggling runners, when we should be saying that guys like Ryan Hall or Dathan Ritzenheim – they run just as well as any ancestor did?

And then perhaps most crucially of all, and this is the biggest flaw in this particular argument, there is very little in our lifestyle that is similar to what it was or is in these communities! For example, 2010 man is sitting at a desk for 8 or 9 hours a day, driving a car 80% of the time of locomotion, and spending maybe one hour a day doing exercise. Even as children, we are less active, playing less outside and more on computer games. Many years ago, hunter-gatherer humans were playing, physically active for 12 hours a day and thus developing the strength that perhaps allowed them to run for enormous distances without the same injuries. And yes, they happened to be barefoot! But there are about a hundred things they also did differently. Yet for some reason, we’ve looked at this picture and said “The big difference between us and them is that they were barefoot”. We’ve spotted the wrong difference – the reason they did what they did is because they were stronger in the supporting muscles as a result of their lifestyle. We are weak, unprepared for hours of impact while running, and shoes just happen to be a new addition while this has happened.

Bottom line, don’t blame the shoes for the injuries, look at the training and degree of physical readiness for running, because 9 hours of desk work and years of inactivity produce weakness and inflexibility that is found out by 60 to 70 km a week of training.

Part 5 next

So that's Part 4 done. Apologies for a long post today, but hopefully it stimulates the same kind of discussion!  Tomorrow may be the last post, certainly it will be the last of the interview, and then I may manage to squeeze in a post at the end to wrap up.  So join us tomorrow! 

Ross

Barefoot running and shoes Q & A Part 3

Barefoot running and shoes - the Q & A Part 3

Today we forge ahead with the Q & A I did earlier this year with Run 2 Day magazine, which I've cut into segments to make up a series while I'm traveling.

Yesterday, I posted twice, dealing collectively with some the questions around barefoot running and running shoes, the mechanical changes they cause, and some of the possible physiological consequences of these changes.  Clearly, there is a lot more to be said than even what I did, but I'm moving on with Part 3 today, and looking at some of the shoe research out there.  After the information overload yesterday, I'm going with only two questions today - 8 and 9 in the series, looking at some of the questions around shoes in particular.  Enjoy!

8. Is there any evidence that either (shoe or barefoot) is better in terms of both performance and injury prevention?

No conclusive evidence, as I’ve mentioned in the previous posts.  There is however some circumstantial evidence for both sides – the shoe industry didn’t grow into a billion dollar one based on rumor only – there is some science behind it. It’s just that it’s pretty weak, failing to show that the prescription of certain shoes to certain individuals actually does anything to prevent injury (Richards et al, 2009), and failing to show that the shoes contributed to the injury in the first place.

A study published in 2007 attempted to pull together all the research on running injuries (van Gent et al, 2007), and a few things were pretty clear. First, there were very few good, scientifically sound studies investigating running injuries and their cause. Incredibly, given that running is the most studied sport, and that the prevalence of injury is up above 60%, only 17 studies were deemed of sufficient standard to be included in the review. It’s quite amazing. The only thing that study really concluded was that training volume was highly predictive of injury.

On the other side of the table is a growing body of circumstantial evidence for why shoes may not work. For example, the loading forces are not different in new and old shoes, because runners change their kinematic patterns (Kong et al. 2009).  The table below shows the measured changes in the study.  I apologize for not redrawing it for you, but time is tight.  I've highlighted the main finding, which is that the maximum vertical force (Fmax) and the maximum loading rate (Gmax) are not different in worn shoes (200 miles of running).  The study also found that there is less forward lean and more plantar flexion in worn shoes, and that stance time was greater in worn shoes.

What the study didn't measure was muscle activation, which is something I discuss in Question 10 (tomorrow, probably), because that would likely have been different too, as the runners adjust their muscle activity to maintain constant tissue impacts - this is called muscle tuning, a concept that is really important in how we understand the body's cushioning ability.

The eventual conclusion of the Kong et al study was that runners should choose shoes based on properties other than cushioning, because the body will find the ideal cushioning anyway. This doesn’t suggest that the gadgets designed to prevent injury through cushioning would be that effective (or, of course, that shoes wear out, if you wish to adopt that position!).

Another study found that runners who ran in the most expensive shoes were just as likely to get injured as those who ran in the cheap shoes, lacking all the protective gadgets and functions (Clinghan et al, 2008). Here, there is the counter-argument that the runner who buys the very expensive shoe might be more injury-prone to begin with – perhaps they buy the shoe because they have a history of injuries, whereas those who settle for the cheap shoe do so because they’ve never been on the receiving end of running injuries (the study did control for running volume, by the way, in case you’re sharp enough to be wondering if the cheap shoe buyers ran less).

We also know that the shape of the foot is altered by wearing shoes, and so is its function (D'Aout et al, 2009). This study was brought to my attention yesterday, and it’s interesting because it shows that the “natural” shape and function of the foot changes with chronic shoe-wearing, which provides something of an explanation for why it’s so difficult to go from years of wearing shoes to running barefoot.

And then most recently, it’s been found that if you prescribe shoes to runners based on the shape of the foot and arch (as is typically done, because people who pronate are supposed to have flat feet – this is often called the “wet test”, where you have to look at the wet footprint left behind to tell you whether you need a motion control shoe or a cushioned, neutral shoe) there's no difference in injury rates. Even controlling for physical fitness and age, you do no better at reducing injury rates than if you just give every runner the same shoe (Knapik et al. 2010).

So the idea that you have to prescribe certain shoes to certain runners, because the shoe is going to help prevent injuries is not borne out by research. That’s not the same thing as saying shoes are unnecessary, mind you, but it does challenge the conventional wisdom. And this is a movement that is gaining momentum all the time.

So currently, there’s little conclusive evidence. Both sides are poking holes in the other’s arguments, pointing out the lack of evidence, but we still await a definitive answer, one that will only really come when a long-term, prospective study is done. As I said, it’s incredibly difficult to find, because injuries are so complex and difficult to predict, and the study to answer this question may be hypothetical only.

9. If there is evidence for the opposite, why does everyone - including manufacturers - believe that shoes prevent injury?

Well, for the manufacturers, the answer is obvious – they have a strong incentive to believe their product is not only effective but indispensible. For everyone else, thirty years of investing, marketing and belief, is the simple answer. The shoe industry grew rapidly in about the 1970s, co-inciding with the huge running boom of the time. Until that point, shoes were really minimalist. If you ever have the opportunity to look at the shoes that runners used prior to about 1970, you’ll be amazed at how basic they were. In fact, they resembled the modern day lightweight shoe. No gel pads, air cushions, torsion devices, and certainly no built up heel.

The explosion that accompanied the running boom saw massive financial incentives created, and I don’t think it’s oversimplifying things to say that a market was suddenly created, that this market had a need for a product, and it was lucrative. Then, I’m sure a good number of people with good intentions started to theorize about how they could help reduce injuries, and the concept was born. Once it became conventional wisdom, it was difficult to reverse, just as most things are, I guess. The pervasive message has always been that shoes are vital. It's not difficult to get this message out, because you have to remember that a runner only really thinks about one piece of equipment, which is also his "interface" with the road.

However, and this is the side that none of the barefoot advocates wish to hear, part of the reason we believe shoes help prevent injury is that it’s possible that shoes DO prevent injury, or at the very least enable people to start running! I’ve spoken about the lack of evidence for either position, but there’s good reason to believe that some people’s shoes really do help them run, or run more than they would be able to in those light shoes.

Take a 100kg (220 lbs) man who wants to take up running. Remember, prior to 1970, he would never consider running a marathon. Today, he can, which is a great plus for our sport. However, he may be coming to running from 20 years of inactivity, with weakened supporting muscles, he’s heavy. He may be doomed if he could not get a shoe that provided some support and cushioning, purely because the first few weeks would be so uncomfortable, even in a minimalist shoe, that he may really struggle. Perhaps one day, with enough training, he’d succeed in light shoes (or barefoot), but you would have to work very hard to convince me that this person would ever get off the ground without more supportive shoes. This man, straight into a lightweight pair of shoes, would not be a runner, I have no doubt about this, and so it would be false to say that shoes don’t help at least some of the time.

Next up: Shoe-cushioning, muscle-tuning and intelligent muscles

That's it for now - I know it's probably frustrating when posts end "in the middle of nowhere", but hopefully you can forgive the lack of smooth continuity in favour of shorter, manageable posts. I don't think I've yet figured out how to do these long series!

Next up, I answer a few questions on the cushioning properties of the muscles, as opposed to shoes, and how the body "senses" the ground. But that's for tomorrow, so join us then!

Ross

Barefoot running and shoes Q & A Part 2

Barefoot running and shoes - the Q & A Part II

Earlier this morning, I started a series on the barefoot vs shoes debate, intended to debate the current move towards running "natural" (that is, without shoes).

This is a topic that always inspires passionate responses from both sides of the aisle, so to speak, and the post this morning didn't take long to stimulate debate. Generally, both sides dismiss the other argument out of hand.

I earlier posted the answers to the first three questions of an interview I gave to a Dutch running website earlier this year.  It turns out that perhaps I should have posted the first seven questions, because I've created the impression that I'm totally against barefoot running, which is not true. As the interview will make clear, I think there is substantial merit to the barefoot position, which we recently covered in our post on Daniel Lieberman's research on barefoot running.  

So I've decided to get the next part of the series up as quickly as possible, lest I am seen to occupy the same position as most others in the debate.  I'd like to think I'm objective on this issue, but clearly that is never the case, for anyone.  But here are questions 4 to 7, discussing some issues on the other side of the debate.

4. Our first experience (and the claims of barefoot ambassadors) is that 'barefoot' running forces you to land more midfoot/forefoot, simply because it hurts to land on the heel. This makes your step automatically shorter and keeps your knee bent when landing. Natural running proponents claim this way of running makes the runner less prone for injury. Would you agree that midfoot/forefoot landing, bended knees and shorter steps benefits the runners body? 

The changes in landing and kinematics (knee angle, ankle angle) when you shift from shod to barefoot running are pretty well established. So you’re exactly right – the most noticeable change when you run barefoot is that you land further forward, your knee is bent, and also your ankle is more in what is called plantar-flexion – your foot and toes are pointed away from the body. One of the consequences of these adjustments is that your stride is shortened, but this is at least partly made up for by an increase in stride rate. This is easy to test for yourself – you can run 100m in shoes and without, and count the strides, feel the landing of your foot, and you’ll have confirmed the running science within 30 seconds!

There’s also evidence that the pattern of muscle activation – when different muscles are active during the stride – changes in the final few hundred milliseconds before your foot strikes the ground, and that’s because the brain, anticipating that there is no longer an air cushion or gel pad inside a soft heel, is going to do the job of ‘softening the landing’ for you.  The body is remarkable this way, and this "natural" response to being barefoot is, I believe, one of the most compelling arguments for barefoot running.  The best study showing this cushioning response is Lieberman et al's recent study in Nature, which we posted on previously, and is also summarized on their excellent website.

As for the second part of the question, whether it’s better to run this way, the full body of evidence does not exist, yet.  What has been shown is that a shift in running technique can change the loading patterns, so that the eccentric loading on the knee is reduced when the forefoot/midfoot landing is used.  In contrast, the ankle loading rises compared to heel striking.  This has important consequences, which we'll definitely discuss later on.  Changing the loading pattern and the eccentric loads in particular will affect injury risk.

However, nobody has yet done the study that changes a runner's technique and then tracks them over many months, or years even, to see how their injury rates change.  This would be a mighty difficult study to do – it would have to be very long-term, and control for a number of other factors (weight, running speed, training volume, training history, skeletal dimensions because there would be considerable individual variation between people, and so on – too many factors contribute to injury for there to be a keyhole study to find the answer). But the key is that nobody has really provided the evidence.

And in theory, the verdict could go either way. Either you are an advocate for barefoot running, and you believe that the bent knee and forefoot landing is protective, and you cite studies that have found reduced impact forces when running barefoot, such as the recent work by Lieberman et al, which is really provocative and breaks through this argument for the first time. Even here, the practical application of the research is not so simple – just because the impact force, particularly that initial impact, is reduced, does not mean that a habitually shod runner switching to barefoot running will reduce injury risk.

Or, on the other hand, you might choose to adopt the position that being barefoot simply changes the loading patterns, not the load, and that the extra work being done on the calf and tendons is worse for you. You therefore decided that you need the stability provided by the shoes and that barefoot running will never work. Note here that you don’t exactly have a lot of evidence to support this position either!  30 years of shoe research has not shown that shoes protect runners against injury.  Neither side has this study.

But apart from all the scientific debate, and the discussion around whose evidence is stronger, what it means, there is a practical problem with making the change from shoes to barefoot running, and that’s what the marketers have overlooked.

This is my biggest word of caution in this whole debate. When you run barefoot, you are changing loading patterns and muscle activity considerably. Your calf muscles and ankle joint, in particular, do  more work running barefoot than in shoes. The same is true for newly-trained Pose runners incidentally – the loading on the ankle goes up while the loading on the knee decreases. The problem is that the calf, Achilles tendon and ankle are not used to this and you pretty much guarantee injury.

This is why the scientists who are arguing the merits for barefoot running (Lieberman et al) are being so careful to encourage a prudent approach to barefoot (or Vibram) running. Unfortunately, that prudent approach has not been shared by media or marketers, which is why they had to issue a statement on the front page of their website after their paper in Nature.  That statement is testament to the challenge faced by runners who switch to barefoot and it should be cold water on the hostility they often show towards anyone who dares to suggest that they are at risk.

This situation is much worse if you force the forefoot landing, which is what many people do when they read the marketing hype – they go out and force themselves to land on the forefoot, which is a recipe for disaster, because the only way they can achieve this is to point their toe down, by actively contracting the calf. Suddenly, four times your body weight is being thrown onto a contracted calf muscle, and the only outcome is a very hurt soleus muscle, or worse.

So the short answer to your question is that if you’re not careful about how you run barefoot (or mid/forefoot, in the case of Pose), and how you teach your body to do it, you basically guarantee yourself an injury, which makes you worse off than running in shoes.

I think that people will under-appreciate how difficult the switch can be, and a lot of people will injure themselves because of misinterpreted science. Out of 100 people to attempt barefoot running, I’d be surprised if 30 pull it off without some ‘trauma’, and I’d be willing to be that at least 30 pick up an injury that forces a long lay-off, maybe a return to shoes.  Of course, 30 will succeed and be much better off, which may power the movement even more.  You are far more likely to hear about the success stories than about the guy who damages his Achilles tendons in a week and abandons the plan.  And well done to those who succeed - they've found a solution.  But to suggest that this solution will work for everyone may be making the same error that others have made before.  Quite what determines who succeeds, I don't know.

5. What about the act of shifting the pelvis as chi running proposes and the relationship to mid/forefoot landing?

This is the correct way to change the body position during running, and you see it in a number of athletes who run efficiently (and who have never heard of Pose or Chi, incidentally!). You simply cannot run when you are leaning backwards, with your weight behind you. So by getting your pelvis forward, you bring your body more into an effective running position, and one of the consequences is that your footstrike will move forward slightly, since your feet will be moving under your body, rather than reaching out for the landing on the heel.

But the key, again, is that you can’t control the landing cognitively, it is the consequence of otherwise good form. And crucially, you can have this good form and still land on the heel! You cannot judge a runner’s efficiency by looking solely at their footstrike, and this is a problem I have with how the whole debate has been positioned. The contact point of the foot is a consequence of numerous other factors, pelvis position being one of them. It’s not the diagnostic, or the fingerprint that identifies good vs bad technique, and a lot of runners would be better off not worrying about the foot.

6. The above is a health perspective on the advantages of running with a shorter stride and lending on the mid/forefoot. What do you think about the claim that the runner is faster in this way of running, due to the fact that it is a less energy consuming way of running (obviously speed over longer distances, we’re not talking sprint here)?

Same as for the injury aspect – there’s no evidence for this. The theoretical argument once again works both ways – there are some studies that suggest that landing on the heel produces the most efficient energy return and produces the lowest oxygen consumption for a given speed (which immediately contradicts the basis for the question). However, other studies have shown the opposite, which means your question is valid after all! So the jury is well and truly out on this one!

It’s interesting Haile Gebrselassie is very clearly a heel striker during marathons, though he was a famously reported forefoot striker when on the track, often being pointed to as the unwitting endorser of forefoot landings.

There is also the practical issue that someone who is a heel-striker, and who suddenly decides to switch to a mid-foot or forefoot landing because they think it might be more efficient is highly unlikely to be able to run very well, and risks injury anyway (see Q4)

And finally, a study on Pose found that months of supervised Pose training succeeded in shifting the landing point to a more forefoot one, but the runners were LESS efficient than before, by a considerable margin. So the possible benefits of forcing yourself to land on the mid-foot may be small (or non-existent), whereas the downside includes serious injury to calf, Achilles or ankle, and overall, I wouldn’t force it in a runner until evidence is absolutely convincing.

That’s not to say you cannot introduce training methods that very gradually, and unconsciously, help to improve running by (among other things) changing running form. Form drills, uphill running, sprinting are all training methods that will have natural effects on form. I see these as distinct from cognitively changing technique, which is what this debate leads to.

7. There seems to be lot of debate between researchers at the moment on the subject. Which of the two parties (barefoot vs. modern running shoe) do you see as having the most valid research outcomes at this moment?

At the moment, the barefoot position is in the ascendancy. I realize that in this interview, I’ve said that evidence is lacking, but I still believe they have merit. The problem is that neither extreme is likely correct.

The extreme view that shoes protect against injury and are necessary and should be prescribed according to specific tests like foot shape is very much in doubt. That’s why the barefoot group occupies the stronger position – their ability to cast doubt on conventional wisdom is better than that of the shoe advocates to criticize the position that being barefoot is better. I think the conventional wisdom about shoes is changing, more and more people are recognizing that all the gadgets sold as injury prevention devices are not effective, and so the minimal movement gains momentum.

Having said that, the extreme view that we should be barefoot or in minimal shoes is just as likely incorrect. There will be a middle ground where the best scenario for the most people exists. I believe that shoes are crucial for some runners, who would be unable to run without the level of cushioning and support they offer. In theory, maybe barefoot works for everyone. But years of deconditioning and wearing shoes, along with biomechanical factors, may make it absolutely impossible for some people to make the transition. So now you have a choice - run in shoes and keep going 10km a day, no problem. Or shift to barefoot and run a few hundred METERS a day and break down injured. It's just too difficult, practically, for some people to shift.

For others, perhaps a majority, smart training and gradual progression can see them running successfully and injury-free in lightweight shoes. And “smart training” includes some barefoot running, even if it is once or twice a week, for reduced distances. I’ve no doubt that it helps and may protect against injury, and I think it is a matter of time before there is some evidence for this. But neither side is going to convince me that they’re 100% correct in the extreme, and shoes are not endangered species just yet!

Looking ahead to Part III

So again, I apologize for the information overload today. Two posts in a day is a lot. Next time, hopefully there'll be only one. So far, I've looked at the issue from the side of the barefoot. Tomorrow, we'll look more at shoes, and why this perception exists that shoes prevent injury, how marketing messages have shaped those beliefs, and what scientific exists (or is lacking, as the case may be) supporting shoes.

Join us then!

Ross