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!

Running technique: The Footstrike

Heel vs. Midfoot vs. Forefoot: How do elite runners land?

I've finally gotten around to this post, which is probably two weeks in the making, and it follows on from our recent series on running shoes. That series began by looking at whether shoes are in fact as much a cause of injury as a cure, and then evolved into a discussion of how the running market is evolving. Twenty years ago, it was all about motion-control shoes preventing overpronation to prevent injury. Today, it's all about running "barefoot in your shoes", as companies try to go back to "natural" without selling you "the Emperor's clothes", in effect! (It's quite a long post, my apologies, but a lot of important information to get through...)

The next logical question is to ask how is the foot supposed to land during running? This question evolves out of the discussion of shoes. vs barefoot running, and is often at the heart of discussions on running technique. Very often, debates of "technique" tend to start from the feet, jump to the knees ("lift your knees") and then skip to the arms, and that's about it! We won't go into too much detail on technique today, focusing instead on only one of many aspects - the landing of the foot, and particularly, whether the elite runners tend to land on the heel, the midfoot, or the forefoot.

Elite runners footstrike patterns

Perhaps surprisingly, there are very few studies looking at elite runners and footstrike patterns during actual races. Despite this, until recently, the overwhelming majority of coaches and experts were advocating that heel-striking was the most effective technique, simply because most athletes did it. That claim will come up again, but the perception that it was most effective has, over the last few years, been changing. And with the advent of Pose and other running techniques, as well as the observation that not all elite runners are landing on the heel first, people have now begun to advocate that forefoot landing is better! So we have this 180 degree shift, often in the absence of any substantial data to support the claim.

I am sure that many will have seen this kind of assertion (this one is from Wikipedia):

Leaning forward places a runner's centre of mass on the front part of the foot, which avoids landing on the heel and facilitates the use of the spring mechanism of the foot. In other words, landing on the heel is bad, to be avoided...

Or there is this, from Gordon Pirie (admittedly somewhat older):

"Running equals springing through the air, landing elastically on the forefoot with a flexed knee..."

But what is "better"? Where science has yet to catch up with opinion

It's important at this point to ask the very pertinent, but infrequently asked question: "What does 'better' mean?". In other words, when people are advocating that it's 'better' to land on the forefoot, what do they mean? Is it faster? More efficient? Less injury-prone? The fact is, the word "better" is used without studies specifically looking at any single one of these aspects. And the 'prudence concept', as applied to science, says that you cannot say something is "better" unless it's been studied and compared to the alternatives. Unfortunately, the science lags behind in this regard.

So for example, above you have the quote that you are supposed to land elastically on the forefoot. That implies performance and efficiency, which might be true for short exercise, lasting a minute or two. But in an event like the marathon, are we sure it remains the "better" option? If you went out and ran 2 hours today, landing on your forefoot instead of landing as you've always done, what would be the likely outcome? Chances are, you'd be hurting for a few days, with calf muscles that you had perhaps forgotten you had! Worst case scenario, you'd be injured for months with an Achilles tendon injury. That is certainly not a desirable outcome. So there are problems with making sweeping statements about landing patterns.

But more than this, these kinds of statements are never grounded in proof. So for example, when it's written that you land "elastically", has anyone ever done the study of elastic energy return in different types of running? They haven't, but there is theory about it, and that's where these recommendations come from. So the approach in the discussion that follows is for me to adopt the role of "questioner", playing Devil's Advocate, with the humble admission that science simply does not know the right answer, only the possibilities...

Looking at one particular study - elite 21 km runners

So in the current climate where real evidence is scarce and opinions hold sway, let's take a look at one study that has examined footstrike patterns during running events. It was done in 2004 in Japan, and published in 2007 in the Journal of Strength of Conditioning (not sure of the reason for the delay - it happens sometimes in science!). The full reference, for those interested, is Hasegawa et al., J Strength & Cond., 2007, (21), 888-893

It was performed at the 2004 Sapporro International Half Marathon in Japan. The scientists set up a high speed camera (very important for accurate collection of information - beats YouTube science any day!) at the 15km mark of the race, and captured most of the runners coming through. In total, they were able to observe the foot strike of 248 men and 35 women, and characterize them as either heel-strikers, mid-foot or forefoot strikers. They also measured Ground Contact Time at the 15km point.

The finding - what do you expect?

Before giving their main finding away, take a moment to guess what they would have found...If you are anything like me, and have read the substantial amount on the internet and in books about how it's "better" (there's that word again) to land on your forefoot, then of course, your expectation might be that they found:

• The majority of runners land on the forefoot
• Those that DO NOT land on the forefoot are the runners who finish towards the back of the field

Well, if that's what you thought, you'd be completely incorrect...! Because the finding is the following:

• The vast majority (75%) of the elite runners land on the heel
• About 1 in four (24%) runners landed on the mid-foot
• Only 4 out of 283 runners landed on the forefoot

Those runners that landed on the forefoot did not finish in the first four positions, so the common argument (a flawed one) that the best athletes are forefoot strikers is not supported by this finding.

Possible conclusions - how you read the study is influenced by what you wish to prove...

So, given this, one is tempted to say that the landing of the foot makes no difference to overall performance. Of course, this is not necessarily true. As I wrote above, science is often taken out of context, and this is one such example. You cannot, for example, rule out the possibility that these heel-strikers might be a few seconds or minutes faster if they just learned to land on their forefoot! Personally, I think that's highly unlikely, and what is more likely is that they'll end up in rehab for Achilles injuries, but even that is a "bald assertion", based only on opinion!

Now, however, here is where it gets interesting, and this is where the forefoot advocates got quite excited. When the researchers divided the finishers into groups of 50, they started to see something of a change in mid-foot landing as you moved further down the list. In otherwords, there was a higher percentage of midfoot strikers in the first 50 runners than in the second, and then third, and so on. The graph below shows this for heel-strikers and mid-foot strikers (I haven't shown forefoot, because it's so tiny and insignificant by comparison):

At first glance, the conclusion from this graph is that if you want to be a faster runner, finishing higher up in the overall order, then you should be a midfoot striker, not a heel-striker. That's how many people interpreted the finding. And this may well be true. Unfortunately, there is another possible reason it looks like it does - perhaps it's simply a function of running faster.

Speed and footstrike

In otherwords, you naturally shift your contact point with the ground further forward when you run faster. The average speed, incidentally, of the first 50 runners was 3 minutes 3 seconds per kilometer. The second group of 50 runners averaged 3 minutes 10 seconds per kilometer. Hardly a big difference, but given the range (the 50th runner is at least a minute behind the 1st runner), is it possible that groups of 50 is too big, and that all this "finding" represents is a speed effect on footstrike?

The point is, this study does not allow you to differentiate between three possibilities:

1. Faster runners are midfoot strikers (could be co-incidence or some other cause); or
2. Midfoot strikers are faster runners (and therefore we should all change our running style and land on the front part of the foot more); or
3. All runners would eventually be midfoot strikers, if they just ran fast enough!
   

This is another classic example of how a scientific result can be taken out of context and applied to give advice that may not be 100% correct.

Personal opinion and implications of this study

My personal reaction to this research, when it came out, was that it disproved the popular theory that all runners should be aiming to become midfoot or forefoot strikers. Most of us (well, I'm in this group, apologies if you are not) are nowhere near the elite level, and we're often told by experts and coaches that the elite are landing on the ball of the foot or the midfoot, and so we should too.

But the next time you think of running like Gebrselassie and trying to land mid or forefoot, consider this: if you go out and sprint 100m, you're likely to run on your toes the whole way - because you're running faster, you land more on the mid-foot, or even the forefoot.

Sprinting as you are, you'll probably cover 100m in 14 seconds, which puts you only 1 second ahead of a Bekele or a Gebrselassie in a 5000m race, so is it any wonder they are midfoot strikers on the track - they're running as fast as most of us sprint? The point I'm trying to make is, if you ran the speed they did, you'd be a mid-foot striker too! But just as I suspect they change as they slow down, we all do. So why, and on what basis, should you try to run with the same foot strike when you are running perhaps 3 minutes per kilometer SLOWER than them? Again, these are relatively bald assertions, but hopefully you recognize the implication of speed on foot strike.

So when you go out and run a 3 hour, or a 4 hour marathon, that's another story altogether. And what the Pose running study at UCT showed me a few years ago is that if you change the landing of the foot, you predispose the athlete to injury - that study took a group of runners and within two weeks had them all running on the midfoot (please don't write in to say that Pose doesn't mean midfoot, because Romanov was the coach and he was happy with their technique!). Two weeks later, they all broke down with Achilles tendon injuries!

Why? Because sitting where you are right now, if I was to walk into your office or your home and take you outside and ask you to please run landing on your forefoot or midfoot, I can pretty much guarantee that the way you would achieve this is to point your toe down...you're probably doing this as you read this - contract the calf, and point your toe away from your body, like in ballet. Now imagine your body weight landing on that contracted calf muscle 85 times a minute for 4 hours. That, simply put, is a recipe for disaster.

However, if you can gradually change your landing, then I do believe that you can shift your footstrike. But it's a gradual process. And more important, what is the point? There is no evidence that heel-strikers are injured more, no evidence that mid-foot runners are faster and perform better than heel-strikers, and so the ultimate question is:

Why would you want to change your foot landing to begin with? Science has little to offer you in support of this. And so my advice, having read this far (well done!), is to forget about the possibility that you're landing "wrongly", and just let your feet land where, and how they land, and worry about all the other things you can when you run!

If there is one thing you change in your running, don't focus on your footstrike, but rather on WHERE your feet land relative to your body. Because if you are over-reaching and throwing your foot out in front of you, that's a problem, but what happens when the rubber meets the road is less relevant!

I'm sure there's more to this topic, based on your questions and comments. As usual, fire away! And remember the humble admission from earlier - science, believe it or not, does not know the answer definitively! (just as we can't tell you why Bekele is so dominant in World X-Country!)

Ross

Late edit to the post - the comments section of the post has been closed (29 Aug 2009) - too many comments flying in to respond (on top of the other 20 posts still getting comments! And I don't want to ignore people!)

I would recommend that you click on "Running technique" in the tabs at the top of the page, and read through those posts to get the full picture and context to this post

Lessons from Two Oceans

Two Oceans Ultra Marathon, and the state of the "industry" - more on the running shoe market

A rather "South African-centric" post today, but for those outside SA, please do read on, or bear with me for the post focusing on one of South Africa's biggest road races - The Two Oceans Ultramarathon (and Half-marathon). This is a race that few outside of SA will likely have heard of, but it's one of the big 2 ultra-marathons in South Africa, along with the 89km Comrades in June.

The race, a 56km cruise around the Cape Peninsula, is without doubt one of the more beautiful races in the world, and if you're reading this from outside SA, and feel inclined to take a "running holiday" in the future, next year in April is a good bet - you won't be disappointed, either by the race or by Cape Town! There is also a half marathon, for those interested in the shorter races. The race profile, incidentally is shown below - a tough final 28km, the marathon mark falling in the middle of the most challenging climb of the race, with another 14km to go.


Most of the runners who've actually completed the race will only read this on Tuesday, after returning to work after the weekend, and so their legs will testify to the toughness of the final few kilometers! Well done, and take a few days off!

The Two Oceans Expo - some observations

But the main focus of the post today is the Two Oceans expo - as with many big races, the three days leading up to the race involve an expo where all the 'players' in the running industry get to show their wares and promote their goods. Think running shoes, clothing, gels, sports drinks and other gadgets and "necessities" for runners.

I was at the Two Oceans Expo for the last three days, and given our recent series on running shoes, it was a first hand tour through the technology. So I thought I'd share some insights and thoughts.

Running shoes - the industry is shifting

Over the last few days, we've done a series looking at running shoes and the possibility that the expensive shoes you were fitted out in might actually be the cause of the injury, and not the solution! And the response has been fantastic - we've received many comments and emails from people, supporting, refuting and discussing the topics, and so it's quite clear that shoes, more than any other topic, touches runners where it counts - their feet! And, unfortunately, their wallets, for it's still the largest expense a runner incurs for the sport.

So it's not surprising that when 20,000 runners gather for a serious running event, the shoes take centre-stage.

I was fortunate enough to wander around and interact with various shoe companies, and have their sales and technical staff explain to me the latest innovations and gadgets that are "guaranteed to make me faster, and injury-free".

What is particularly interesting, given the context of our series on shoes over the last week, is that every year, it becomes clearer and clearer that the market is heading towards a neutral, cushioned shoe focus. The major brands still have their heavy, expensive motion-control shoes, but the trend is without a doubt towards the lighter and more cushioned shoe. I remember a time when the default option was to suggest that the runner get an anti-pronation shoe, simply because they pronated. Remember, pronation is the "normal" movement of the foot - almost everyone has it. But as recently as perhaps 4 or 5 years ago, it was the enemy, and advice was given to stop it at all costs.

That is no longer happening, as far as I can tell. Again, there are brands that still make shoes to stop the movement, but they now seem to be out-numbered by the cushioned shoes, and the default advice that most people are getting is "go neutral". Every company - Adidas, Nike, New Balance, Asics, and Puma (at this particular Expo, that is), has developed some device to mimic or simulate "barefoot" running. Whether it be a flexible shaft in the shoe, or a plate that rotates on the heel, or even the more breathable design, the very obvious trend is towards more movement, more natural, more barefoot. As we said in our last post, the companies are trying to sell "barefoot". And that is encouraging, and I'd love to know the rationale and forces driving that shift.

Market forces - you buy, they make more

In economics (I'm wearing the marketing management hat for this post), it's often said that the "market speaks", and that may well be what is happening with shoes. People may once have tried the heavy, rigid support shoe, prescribed to them by companies who promised injury free running. But time reveals truth, and so with time, it may have become apparent that this was not in fact happening, and so sales of those shoes went down. Nothing speaks to business more loudly that declining sales and profits, and so perhaps we are now seeing the shift, driven by you, the runners, into the more cushioned, neutral shoes? I'd love to see sales figures to confirm or refute this...

The other really interesting thing that was pointed out to me a few days ago by one of our readers is that about 10 years ago, Adidas came up with a "Feet you wear" campaign. Some may remember that - the logo was a foot that had 'evolved' into the shape of a smiling face. The concept back then was to mimic barefoot running, bring the foot closer to the ground, and let your feet decide, they knew best, and so on. That idea then disappeared, but it's the earliest efforts I can recall of a company going that way, even preceding the Free concept by Nike. What is interesting is why that campaign did not take off, and why this current trend might be different? Was that particular shoe range inferior for some other reason? Perhaps the scientific evidence, and the support given to this concept by "experts" in the field, like physios and podiatrists who may be advocating neutral shoes is different now, compared to the late 1990's? Again, it's speculation, though I suspect that industry insiders know this.

I'm curious to see how this develops - I do believe that within the next 5 years, the companies that make the best cushioned shoes will grow, while those who hold onto their motion control shoes will suffer. In marketing, a model called the BCG matrix calls some products "Stars", and others "Dogs" (among other classifications). I suspect that the star of 5 years ago, the motion control shoe, is gradually becoming a dog, and how the industry reacts will be interesting...

Expanding into other areas - the industry and scientific integrity

Expanding from shoes, and looking at the running industry as a whole, what tends to happen at these expos is that everyone abandons scientific integrity (if there was any to begin with!) in order to sell product. And it's astonishing, and often humorous to observe how it is done. Products are being peddled left, right and centre, with little regard for facts. Some of the advice being given runners is frankly shameful. At least one runner, who was standing next to me at a product stand, is going to run the 56km race drinking a protein shake to "take away lactic acid and stop the muscle from being broken down". Anyone who has ever eaten a high protein meal before, or during exercise, will know just how badly this can affect your stomach - I hope he abandons this strategy before stomach problems end his race!

Of course, runners can often be an adventurous bunch, willing to try new things and experiment, often to their detriment. In the last three years, I have been in the medical tent of the Comrades Ultra marathon doing research, and every year, three or four people have to receive medical treatment because they tried a new product on race day and had a negative reaction to it!

Some of the products being sold, and the rationale behind them, is just astonishing. For example, you can buy a cream in South Africa, which you rub on your legs in order to "remove lactic acid from the muscles". It's anyone's guess how it works. Never mind the fact that the lactate (or lactic acid, as it is often incorrectly called) is unlikely to really be the problem for an ultra-marathon runner. I once asked one of the technical consultants to explain how it worked. The answer was that "The cream contains oxygen, which diffuses through the skin, into the muscle and then takes out the lactic acid".

While this is clearly ridiculous, where it becomes more disturbing is that this product is backed and endorsed by a local University, reasoning and all! As we have seen before, when the price is right, science can say pretty much whatever it needs to! (I'm thankful to say it's not my University!) I suspect that where ever you are in the world, you'll be able to relate similar stories and products.

Knowledge is power. The market has the power, what of the knowledge?

And I make these points and give these examples, not to slam the industry or those in it, because they are trying to survive and gain a competitive edge - their incentive is not truth or validity in their claims. That's wrong, I know, but it's the way it is. So you cannot hold them accountable for the myths they perpetuate, unfortunately. Rather, I wish to point out that ultimately, the consequence of the sales-myths is that the athlete, or end-user is compromised, not the company. And as with shoes, you, the runner, should dictate the market by being discerning and severe on these kinds of products. Force the makers, and the scientists who say what they are asked to (this applies to other situations as well) into a higher standard of credibility and integrity.

That, of course, requires knowledge, understanding, and education, which is why sports science, often undervalued, needs a boost in its public profile and perception. I was working at the Runners World stand at the Expo (I am the scientific editor of the SA mag), and people were invited to come and ask questions - none did, and I suspect they do not perceive that there are things they might benefit from knowing. Injury? Ask a physio. Illness? Ask a doctor. But what does one as a sports scientist? Hypothetically, the issue of oxygen diffusing through skin would be one such question! This is also not to say that suddenly the "exalted" field of sports science has all the answers, for clearly it doesn't (and nor do I). But the contrast between what is perpetuated at events like the Expo and the facts is so large, that everyone can contribute to better understanding. And hopefully, fewer people will run marathons drinking protein shakes as a result!

Also, what this does is introduce some really interesting discussion points, and so I did, at the very least, leave the Two Oceans expo with some ideas for articles in the future, and with a greater appreciation of where the various sections of the running world (running shoes, energy products, creams, recovery aids etc.) are heading. I also left with a few other stories and discussion points from chatting to coaches and runners, but that is a topic for tomorrow's post.

One thing I did not leave with, is the anti-lactate cream! Promise...

To all those runners who are taking part tomorrow, good luck! And to all those who read this AFTER taking part, congratulations!

For those not lucky enough to be in Cape Town for the weekend, wherever you are, have a wonderful Easter weekend, and perhaps next year, I'll see you at the Expo!

Ross

Running shoes Part III

Running shoes, barefoot running and muscle tuning: The intelligent biomachine and implications for running

Well, it's been a week and a half, and an interruption of our series on Running Shoes thanks to Gebrselassie's announcements, but I have finally managed to get back to the topic that had caused so much debate and discussion: What is the value of running shoes? Do they cause more problems than they fix, and what is the future of the running shoe industry?

One argument that has been put forward a great deal is that barefoot running is the way to go. Apart from the obvious practical concerns - glass, stones and other objects not meant to be run on by 'soft' feet - I'm not 100% convinced that the knee-jerk reaction in the opposite direction is the way to go either. I know podiatrists who are of the opinion that the sole function of the shoe should be to protect the sole of the foot, which is in line with what we've been discussing, but a more extreme argument.

I'm sure there's merit in that argument, but I wouldn't dare suggest that any reader of this post suddenly switch to barefoot running, or even to lightweight trainers if they've always worn more supportive motion-control shoes - remember, the key to successful training is managing change, and physiologically, you'll pay a hefty price if you make a drastic change like this. Instead, the objective should be to manage the change, aiming to gradually move away from the bulky shoes and into the well-cushioned one. This requires changes in training, possibly strengthening exercises to correct weaknesses and imbalances that predispose to injury, and then the new shoe should work.

However, the debate between barefoot and shoes is nevertheless interesting, so a few interesting discussion points that arise are considered below.

Biomechanics of shoes vs. barefoot

You have no doubt heard, read or experienced that one of the main differences between running in shoes and running barefoot is that when you run barefoot, you tend to land more on the front part of the foot. In contrast, pull on a pair of shoes and you'll land more on the heel. There are of course other differences - barefoot running tends to have a shorter contact time, a shorter flight time, lower impact forces and higher muscle activation in the calf muscles just before landing. You also land with your ankle more "pointed" (called plantar flexion) as opposed to dorsiflexed, or pulled back towards you. But the argument around landing on the heel vs. ball for shoes and barefoot running is one of the more common ones, and certainly less technical!

The "heel-strike" observation forms the basis of many people's arguments for why a forefoot landing is better than a heel-strike. The problem is, people often get trapped by their own logic when discussing this concept. The thought process when it comes to barefoot vs. shoes is often the following:

1. Barefoot running is natural
2. When you run barefoot, you tend to land on the ball of the foot, whereas in shoes, you land on the heel
3. Therefore, landing on the forefoot is "natural" and good, but landing on the heel is unnatural and thus bad.

Apart from the assumptions of what is "good" and "bad" in all this, there is a hidden question that must be answered first:

Why does the body allow the landing to change simply by pulling on a pair of shoes? Or, looked at differently, if you take off your shoes, why do you suddenly land on the ball of the foot?

An intelligent system - changes in mechanics serve a purpose

The answer to this question must be that when you take your shoes off, your body is "intelligent" enough to adjust your landing in order to reduce the loading force and rate. The change in biomechanics thus serves a useful purpose! This is a conclusion made in many studies. For example: "...barefoot running leads to a reduction of impact peak in order to reduce the high mechanical stress occurring during repetitive steps" (Divert et al. Int J Sports Med 2005). This reduction is achieved in part by changing muscle activation (which we'll come back to), as well as altering the biomechanics slightly as described above - lower flight, different ankle position on landing and so forth. The end result is that you land more on the ball of the foot.

Of course, what people often forget is that if it works this way - taking shoes off - then surely it must work the other way, when you put the shoes on? In other words, when you run in shoes, your body is "intelligent" enough to recognize the added cushioning, and so it allows you to land on the heel. There's no reason to suggest this is bad, but applying the same logic used above, it might actually be a beneficial, positive response to wearing shoes - perhaps landing on the heel is the protective, optimized adjustment to running in shoes?

It's never made a great deal of sense to me, but the key is, the body seems quite capable of changing mechanics and even muscle activation in order to reduce impact forces - and this introduces the concept of "muscle tuning".

Muscle tuning - adjusting for impact

The concept of muscle tuning, proposed by Benno Nigg in Calgary, is both new and quite complex. And I'm certainly not a biomechanist, and so the detail and technical explanations are best left out of this discussion! But the concept has some quite important implications, which we'll get to.

First of all though, muscle tuning is the adjustment of muscle activity in response to impact forces, and it ends up minimizing soft-tissue vibrations and joint-loading. Let's step back a little - when you are running, the muscle is activated BEFORE you land in order to prepare the joints and supporting structures for the impact. This muscle activity is called pre-activation and there's actually a good deal of evidence that suggests that performance is influenced by this pre-activation, since it helps to store up elastic energy and make running more efficient. The muscle is then active during the entire stride, after ground contact, to continue to support and control movement of joints.

What Nigg found is that when you run in shoes with a softer or harder midsole, or run at different speeds, you change the impact forces, but the muscle activation simply compensates and you end up experiencing similar soft-tissue vibration. In other words, your body is "intelligent" enough to adjust muscle at different levels to ensure that you don't have excessive joint loading and tissue vibration.

Where this becomes especially relevant is in the application of the theory to orthotics, running shoes, and other shoe inserts. Because this theory is saying that the muscle activity during running will increase as soon as the "preferred" movement is affected. The use of running shoes, for example, which may well alter the movement of joints during running (think anti-pronation shoes here), will then simply produce an increase in muscle activation which now stands to affect the body's "natural" mechanism to regulate joint-loading.

So in effect, the problem with shoes, orthotics and inserts might actually be that they promote an increase in muscle activation, which prevents this "intelligence" from regulating the normal soft-tissue vibration. Nigg suggests that things like orthotics and shoes should reduce the muscle activation in order to be optimal, rather than increasing it by preventing normal movement. Quite how one establishes this outside of a specialized biomechanics lab is a tricky problem, but that's another matter.

How much do all our interventions (and inventions) actually achieve?

The point for the running shoe industry is to recognize that the best efforts of researchers, product developers and (we have to point out) marketing experts, may in fact be trivial by comparison with the remarkable ability of the human body to adapt and respond to "stress", whether that stress is changing running shoes or long term training.

Of course, problems do develop and injuries do happen, and when they do, it's fascinating to wonder whether in fact the cause might be the change that we try to introduce to fix the problem! Is it possible that clever product development, based on theories and concepts, have actually forced the body into a "wrong" response that has increased injury risk in the long term? And is there a chance that if we just left physiology to its own devices, and managed every case individually, we'd be better off?

So to continue the theme of the running shoe, the shift in the industry has without doubt been towards a more "natural" shoe. Of course, they can't sell "barefoot" (that's free!), so the next best thing is to be barefoot in shoes, which is where it's going. Practically, however, the challenge for everyone is to manage that, and not simply leap from one extreme to the next, as mentioned above.

That's it for shoes for a while, we'll no doubt come back to the topic in the future. But next on the agenda is a series on performance, the brain and pacing, which throws up some fascinating questions and hopefully discussion. So join us then!

Ross

Running shoes continued

Running shoes and injuries: Debate continued

Yesterday, we did a short post looking at the debate around running shoes, and whether the shoes which claim to reduce injury risk are in fact part of the problem! Thanks to everyone for the spirited input on the debate - it's been lively and interesting so far. I thought it better to respond in a new post and perhaps lead the discussion based on those comments than bury my response in the Comments section to that post.

Another study on expensive shoes - money doesn't buy you comfort

First, thanks to Clyde for providing the link to the article from BJSM. You can find the article abstract here if you would like to read it. I have a copy of the article as well, and it makes for some interesting reading.

Basically, the researchers set out to evaluate three differently priced running shoes:

• Expensive - priced over 70 Pounds (around $140 or R1100)
• Medium price - around 60 Pounds ($120 or R900)
• Low cost - 40 Pounds ($80 or R600)

The shoes were evaluated primarily on the basis of pressure under the foot and comfort, which is a subjective rating. So they didn't really tackle the issue of motion-control/anti-pronation devices, which is a pity (but more on that later).

Their findings? As you probably might have guessed based on Clyde's comments and the general trend, there were no differences between the shoes for either of these two factors - the cheap shoes produce the same pressure (cushioning), and the same perception of comfort as the expensive shoes. The difference in price of R500, then, results in little difference in terms of cushioning or comfort or pressure distribution.

In a follow up letter to this article, the reasons for this were pointed out - it's simply not feasible to change pressure by shoe-design, because the result would be a dramatic change in biomechanics - the analogy would be to switch from running on tarmac to running on soft, spongy sand. So in effect, the above-mentioned study was "doomed" to find no difference anyway. And of course, this might be true, but then it introduces the obvious question - if shoes can't change the pressure/cushioning, why the enormous price difference? And that's where the debate leads next...

What is missing - research on the 'gadgets'

This study is interesting in that it evaluates one aspect of running shoe design - pressure or cushioning. However, it fails to tackle what I believe is the bigger source of "controversy" around the shoe industry - all the gadgets and gimmicks that are inserted to provide MUCH NEEDED support to runners who over-pronate.

And a good many of the comments to our previous article are from runners who do pronate and have had experience in these shoes. Basically, the premise for these shoes is that upon landing, excessive pronation, which refers to the rolling in motion of the ankle (called eversion of the foot), is responsible for injury, since the pressures and loads placed on the shins and knees is excessively high. Therefore, control the pronation and you control the injury risk...

So shoe companies have all developed their own unique devices to do this. Apart from the devices that are proposed to aid with cushioning (Nike Air, Asics Gel, Adidas Adiprene, and so on), I would dare say that most of the product (and price) differentiation takes place with regards to these motion-control devices. Yet so little research has been done on them. Well, let me qualify that - there is "overwhelming evidence" on all of them, but they're done exclusively by the shoe companies and never published! The funny thing is, I can almost guarantee that one company will have research that proves their device superior, while another, having done almost identical research, will conclude that theirs is the best available!

So it's hardly surprising that Dr Richards and most of you writing into this post are suggesting that anti-pronation shoes are being over-emphasized, and that a well-cushioned shoe is the way to go.

My personal take on the issue - it's the training, not shoes

So let me take that one step further and actually put my head on the block on this one. I fully agree with that assessment - I don't believe that huge, heavy anti-pronation shoes are the solution for running injuries. I stated yesterday that if I were advising an athlete with injury problems, I'd look first, second, and third at their training, and then start to consider their footwear! The point is, training errors are responsible for injury, the rest is detail!

Of course, factors like biomechanics, muscle strength or flexibility imbalances are contributing factors, and so if a runner is "biomechanically correct" (incidentally, that term is thrown around with freedom but without a clear definition of what it actually means! But that's another issue!), they will get away with training that would cause injury to someone who is not so fortunate. Body size and weight are key factors, and then of course, you get leg length discrepancies that throw off alignment, making some people far more susceptible to injury - the result is that one person's ideal programme is another's "boot camp", guaranteed to break them down in a few weeks!

However, I don't believe that simply changing the shoe is the solution - changing the training, and gradually increasing the load is far more likely to resolve the injury.

At the two extremes (high arches or very flat feet), I believe that orthotics may be helpful. I myself have very flat feet (I could probably walk on water if I tried, and certainly on snow!) and I've been in orthotics before. However, I found they caused more problems than they resolved - super rigid, stiff and heavy. So I eventually ditched them, went back to the drawing board as far as training goes (did I mention that I believe training is the key to injury?), and basically started running as a beginner again - I spent a month doing a walk-run programme, consisting of 5 minutes jogging, 2 minutes walking, and eventually managed to phase out the walking part, and the problems are a thing of the past. And all in a pair of very well cushioned, neutral shoes. I certainly lie on the far end of the pronation continuum, but I really am convinced that given the right training, anyone can wear neutral shoes. I don't believe that buying a super-expensive motion control shoe will improve your chances, rather look at orthotics if you feel you have to obtain some support.

To sum up - when you buy your shoes, try them on for comfort and cushioning and fit, and once you find what works, then stick with it. But don't commit to the 'gadgets', well cushioned is sufficient.

The future of the shoe industry

Finally, if I may put on my marketing hat for a moment, I would predict that the heavy motion-control shoe will one day become an extinct species - it may already be on the endangered list! It's difficult to know what stimulated the massive growth in the area, but I suspect what happened was that in the 1970's, when the running "boom" hit, a good many people with "less than perfect" biomechanics took up running. And of course, marketing is all about meeting people's NEEDS. And when the NEED doesn't exist, then you simply create it - "science" is often a big help in this regard!

So the companies recognized that perhaps a million people who never ran before were now running and this represented a huge market to be tapped into. But they needed a selling point, and Point of Differentiation, and the "combat overpronation" campaign was just the ticket!

Now, in 2008, I feel the opposite is happening. More and more people are talking about barefoot running, which is probably a little too extreme, a case of over-compensation, perhaps. But the point is, there is a shift in the market, and I'm sure the companies will respond and try to create a new need - I suppose they already have, with the barefoot shoe concept. But all this adds up to the beginning of the end for the heavy, anti-pronation shoe, which will probably become a relic in the next 20 years. But then again, those may be famous last words!

Thanks again for the debate, keep it coming!

Ross

Running shoes: Solution or the problem?

Running shoes and running injuries: Do the shoes actually cause the injuries?

After a couple of posts on doping, a bit of a change of theme for today, as we look at running shoes and injuries. This post was inspired by a link I was sent by one of our regular readers (thanks John - the link is further down the page, incidentally) and it's a really great article, a real conversation starter, so it follows on nicely from our great discussion after the previous post on lifetime bans for dope cheats. Thanks to everyone for their input on that one, let's see how this one goes.

The other reason to post links is because we've both been incredibly tied down with other work just lately, so in true academic fashion, we'll borrow from the excellent work that already exists and just steer the discussion and the traffic in that direction! Having initially thought that it was Albert Einstein who said that he had "stood on the shoulder of giants", one of our readers pointed out that it was in fact Isaac Newton! To save face, I will however point out that Einstein did quote Newton by saying this later in his own life, which of course only reinforces the idea that in science, don't say something in a new way when someone has already said it perfectly for you! And so we borrow that concept today and refer to a great article on running shoes and injuries...

The running shoe debate: An old topic revisted

To date, we have not really tackled the running shoe subject directly here at The Science of Sport, but it has come up incidentally in previous posts.

For example, it came up in the first post on our series on the Pose Running technique, where it was pointed out that ever since the "boom" in the running shoe industry about 30 years ago, the percentage of runners who get injured each year has remained pretty much the same.

So despite technological advances and developments in the industry, injury incidences have remained largely unchanged. Shoe companies make many promises, such as:

"Anti-pronation devices limit movement of the foot, reducing the risk of injury in overpronators", or "Forefoot and rearfoot cushioning devices reduce impact and the risk of injury"

Yet there's little reason to believe that this is true. The latest studies suggest that anything between 40% and 70% of runners are injured every year. And fascinatingly, in 1989, a study found that runners who ran in shoes costing more than $95 actually were twice as likely to get injured than runners who ran in shoes costing only $40! That was even after correcting for training and racing mileage! Of course, it's impossible to conclude that "expensive shoes CAUSE injury", because there are other factors that can't be accounted for. And one might argue that the typical runner of 2008 is quite different from the runners of the 1970's, who tended to be lightweight, biomechanically very different athletes. So maybe the fact that the injury rates are the same is actually a positive for the shoe industry? But let's pursue it a little further...

Points of differentiation and running shoe research

And what is more, the companies very rarely make their research available for all to see. Even if they did, you can pretty much guarantee that the research (which would be funded by the company, remember) would show "conclusively" that the shoe positively influences biomechanics, cushioning and hence reduces injury risk. The cynics among us would challenge the research on the grounds that they company could hardly spend money on scientific research and conclude that their latest selling point on the new models DOESN'T make a difference!

And in order to understand the full extent of the issue, you have to appreciate what is relatively obvious from a marketing point of view - all shoe makers are doing their utmost to differentiate their shoes and get their "share of wallet" in what is a very competitive, very lucrative (billions of dollars), but very cluttered market. The result of this search for a "point of differentiation" has thrown up a dizzying number of gimmicks and gadgets - every company has their solution, their distinctive features, often with the same function as competitors', yet it's still called "cutting edge technology".

A great article on running shoes

For a great article on the shoe industry, right the way from the Pharoahs of Egypt, through the Middle Ages and then onto the modern shoe industry, here is a great article on running shoes:

Athletic Footwear and Running Injuries

The article is pretty long, but worth the read. For the latest information and some real thought-provoking writing, I'd recommend Part II, about a quarter of the way down the page, which focuses on running injuries and how the shoes have failed to alter the injury rates.

Another site that may well develop into something in the future has been set up by a research in Australia, Dr Craig Richards - it's called "Barefoot versus the shoe"

He actually contacted us recently, in connection with some other articles here (fatigue, Pose), and we discovered the blog then. The posting frequency is relatively low, but it's worth reading simply to see what the shoe companies say in response to Dr Richards when he challenges them for their research. Hopefully in the future, he'll post more regularly and keep exposing the industry where it needs to be exposed.

Is barefoot running the way to go?

On the note of Dr Richards' blog title (Barefoot versus the shoe), the argument is growing that running barefoot is the natural and hence the "correct" way to run. And I know of many podiatrists who are gradually shifting their thinking in this direction - if any of you out there are podiatrists, please feel free to weigh in on the discussion. In fact, even the shoe industry has cottoned onto this idea - think Nike Free, and the other shoes that are now being made to mimic barefoot running.

But, a word of caution here. If you're a runner who has been pounding the pavement for 20 years in a pair of shoes, suddenly switching to barefoot (assuming you can run barefoot - I would never consider it on the tarred roads of Cape Town) may be a risky move for you. Because the change in biomechanics and loading of joints, muscles and tendons threatens injury if you're not careful. So in the article, you'll see advice to run barefoot - what you may miss is the proviso that you start with "small doses", which is really important - be careful about over-compensating and injuring yourself on the other side!

Any shoe experts out there?

I suspect that everyone has an opinion on this one - I have no doubt that many of you reading this will be able to share your experience that a persistent, nagging injury suddenly cleared up when you switched shoes, and perhaps you've never looked back? Those stories are very common, and lend support to the idea that a certain shoe will help with injury risk.

Personally, I'm of the belief that an injured athlete should look at their training as the first port of call after injury. The second port of call is probably training as well, followed by things like muscle strength or flexibility imbalances, and then in fifth, have a look at your training! Seriously though, I think that one consequence of a pre-occupation with shoes and injury prevention is that it takes away the attention that should be given to training - an injury can almost always be traced to a change in training intensity or volume, and that's where I'd begin the detective work, not with shoes.

But, let's hear from anyone who has experience or knowledge. I know we have many readers who are involved in the industry, and have a great deal of technical knowledge, so do fire away!

A look into the future

So that's it as far as "standing on the shoulders of giants" goes - in the next few days, I'll hopefully get that long-awaited post on fatigue up, so join us then!

Ross