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

Running Economy Part III

Training techniques to improve economy (or should that be performance?)

Today sees the third and concluding part of our series on Running Economy. It's been a whistle stop tour of a complex subject. We have no doubt that we'll be returning to the topic in time, because it has major implications for how we understand fatigue and performance, but for now, we stuck to the boundaries - there is a lot to be written in the coming week! But hopefully today we'll provide some 'meat' that might help explain economy a little more, as well as provide some practical insights into how it can be improved.

On that note, there's a very valid question about whether you should worry about training specifically to improve your running economy, or whether good, common sense training just happens to improve economy as you do it.

I was out on a training run just yesterday, and have a 10 km loop that I do once in a while. Compared to about a month ago, when I just started running again after a layoff due to illness/injury, I covered the 10km a minute or so faster, running at the same effort level as before. And it occurred to me as I was jogging along that if I were to put on my scientist's hat (or lab coat, if you wish), I would probably find about four or five reasons to explain how I can run faster with the same level of effort - running economy would be one of them, for sure.

So in other words, scientists are sometimes very good at looking at the runner (or sportsman) after the fact and working out that X, Y and Z have changed, and that must explain the faster running, when all along, it's the simple fact that you've been running that explains it! Had I consciously spent the last month trying to improve my economy to help me get faster, chances are I'd only improve by the same amount anyway, or maybe even less!

The point is, sometimes the simplest solution is the best one, and that is the case with running economy. Over-complicating things by trying to target what we've emphasized is only one of many factors contributing to performance is likely to be a bit of a self-defeating task - rather just train, and let it happen!

The best way to improve running economy - just run!

Don't worry, that's not all we have to offer as practical advice for today! But it's the most obvious and truest statement we could make! When it comes to training, practice makes perfect. A great illustration was provided a few months ago when we were discussing Pose Running Technique, and we came across a study that looked at the oxygen cost of running in a group of athletes who had been taught Pose for 12 weeks.

What one would predict is that when learning a new running technique, the oxygen cost would go UP, because you'd be less economical as a result of doing a task that is relatively unfamiliar. And sure enough, that's what they found - running economy was worse when running Pose. A number of people wrote in and said this was expected, and that given more time (than the 12 weeks of training in the study), the Pose Runners would improve their economy. Maybe that's true (the debate about Pose was covered back then, you can link to the posts and read it), but the point is, within 12 weeks, economy was still worse.

Turning that around, it implies that regular running will improve economy. We don't often think of running as a task that requires co-ordination, timing, balance and motor control, but it most certainly is. If you ever want to see that in action, then you need to watch an elite runner training. They move differently from you and me (OK, from me - you may be one of them!). I remember standing track side as SA's Olympic Silver Medallist Mbulaeni Mulaudzi did some 300m repeats once, and being struck by the fact that he just moved differently - the flick of the heel during the swing, the arm carriage, knee drive etc. are all subtly different and I have little doubt that this neuromuscular control, while not exclusively responsible for performance, plays a big part, especially in distance runners. There are some other factors, which we'll touch on in a moment, that also contribute to this, though.

Endurance running - what do the studies show?

A couple of problems exist with the scientific literature on running economy. First, there are surprisingly few studies - remember, running economy was called the "forgotten" variable by one author (Carl Foster). Secondly, the initial level of fitness and ability of the runner plays a huge role, as I'm sure you can appreciate - a good runner needs very different training compared to a novice. So it's a little tricky to tease out the valuable information.

In general,however, research studies support that running economy improves with higher volume, slower running. So longer and slower distance training is more effective as a means to improve economy. The reasons for this include the increase in mitochondria, which means more effective use of oxygen by muscle. Also, it's been found that the longer and slower running eventually leads to a 'learned' neuromuscular response where the vertical oscillation of the runner is reduced. In otherwords, less time going up and down, more energy saved, and this is simply a function of repetition!

Now here's where things get tricky! Many of you are probably thinking "what about speed work?" Surely that will see massive improvements in running economy? There's always confusion about whether faster runners are more or less economical. And here, the general rule is that it follows what one might call The Law of Specificity, which basically says that you'll be good at what you train for! In otherwords, if you are a middle distance runner (800/1500m), then you'll be more economical at higher speeds than a marathon runner at those higher speeds. The interesting thing is that it's been found that this same middle distance runner then becomes less economical at the slower speeds than the marathon runner. So again, economy is good where you train it, which to me really re-inforces the value of training specifically, and how important co-ordination and motor control are!

So the take home message - if you're talking novice runners, with little running behind them, then any running will make a difference (as it did for me in the last month, I'm sure!). This is the point I made earlier - economy improves with fitness, and so any running is beneficial. But if it's performance you're after, and the very small improvements that make a big difference to performance (not just economy), then other forms of training become more critical. This also illustrates the complexity of training, and this is where we get into plyometrics and strength training.

Strength and plyometrics

Let's deal with strength training first. There is evidence that strength training improves running economy, probably because it improves the function of the neuromuscular system. In order to understand this, we first have to run through an admittedly basic introduction to an important concept known as the Stretch Shortening Cycle.

Basically, when you are running, a great deal of muscle activity occurs in the milliseconds BEFORE your foot lands on the ground. Why? Well, the muscle is 'pre-activating' in order to increase stiffness of the leg and joints ahead of landing. The stiffer muscle not only absorbs more shock, but it also helps the muscle-tendon unit to store more energy.

Think of the muscle-tendon as a spring. When you land, the muscle lengthens, in what is called an eccentric muscle contraction. As soon as you then push off, for what is called the concentric part of the running stride, you can 'harness' the energy that was stored when you landed. The concentric contraction is more powerful and more efficient, if it follows the eccentric contraction. It therefore uses less oxygen and energy to do the same job, or can do a better job. This is why if you want to jump up as high as possible (for example, to slam dunk a basketball), you bend down and then 'bounce' back up - you are taking advantage of what is known as the "Stretch-shortening cycle" to improve the performance of your jump.

The same goes for running, where this Stretch shortening cycle is critical to performance. The result of all this pre-activation and concentric-eccentric contraction is that the CONTACT TIME is reduced, and performance is improved. Fatigue during the course of a 5km time-trial has been shown to impair the ability of the muscle to "pre-activate", and the result is that your contact time with the ground goes up. Imagine a ball bouncing off a wall - if it gets softer and softer, it bounces off much more slowly, whereas a very stiff ball returns quickly (golf ball vs squash ball, for example).

How does this relate to running economy and strength?

Well, apart from the obvious theory which is that the muscle is stronger, the theory and evidence is that strength training improves running economy specifically because the contact time and reflexes that control the neuromuscular system are improved.

In particular, there is a type of training, known as PLYOMETRIC training that has been theorized to be very effective as a means for improvement of performance and running economy.

Plyometric training

Plyometric training is an explosive form of strength training, which uses drills like hopping, bounding, jumping, skipping and sprinting. During plyometrics, you are exaggerating the stretch shortening cycle, causing major eccentric and concentric training, and this helps to improve the efficiency of the whole system. The result is that the athlete is better able to store and use energy, and therefore the muscle can produce the same force (and hence running speed) with less energy demand, so VO2 goes down. Also, there is evidence that plyometrics increases the stiffness of joints, and stiffer joints are better able to store and release the energy, again saving the cost of running without sacrificing speed.

There is a very intriguing theory that African runners have a more developed, better functioning stretch shortening cycle that Europeans. Also, a Finnish scientist (Paavoleinen) found that plyometric training improved 5km time-trial performance by 3% (this was in quite good and highly-trained runners, so 3% is no laughing matter), which was associated with reduced contact times and running economy (8% lower).

Having said all this, beware of overdoing plyometrics as the "Secret weapon" for your training! The risk of injury is high, and so this should neither be tried out by novice runners, or done too often. It's a very effective method of training if done properly though. I certainly don't coach athletes without also using this kind of training, though it takes different forms, depending on the athlete - sometimes hill running is sufficient, whereas other times, you can get creative and come up with all sorts of drills, using hurdles, ropes, and your imagination! But again, not something that should be overdone...

Flexibility - you CAN be too flexible

The final component of training we look at is flexibility. There was a time when athletes were being drilled to do as much stretching as possible - failing to do so, we were told, would predispose you to injury. Well, injuries aside, there is evidence the being TOO flexible also negatively affects running economy, and thus possibly performance.

There is confusion about it though (as usual, I guess!). One study, for example, found that improving flexibility of the hip flexors and extensors(to lift the knee) resulted in better running economy. The argument here was that if you are flexible enough, and provided you have balance between left and right, front and back, then you need to do less work to balance and stabilize the body during running.

But then other research has found that being less flexible is better. In fact, more studies show that less flexible runners are more economical than the other way around. For example, from novice runners all the way to elite runners, it's been found that as the flexibility in the trunk (hips, and core muscles) and the legs improves, running economy is lower. Therefore, if you want to be economical, you'd err on the side of being inflexible!

The theory behind this option is far more believable to me. We've discussed how the stiffness and ability of the muscle to store and then release energy helps with running and reduces oxygen cost above. Now, the same goes for flexibility. If you are very flexible in the legs (especially the calf and ankle), then you need to do far more to stablize and store energy, and so it pays to be stiffer, less flexible.

As far as the core muscles and trunk go, the less flexible you are, the more stable the pelvis is, and the less muscle work is required to limit the motion as you run - you're a more 'compact unit' so to speak. To sum it up then - less flexibility means less work required for stability and also more elastic energy return from stiffer muscles and joints. I therefore tend to believe the theory that being less flexible is better for running.

Having said that, it doesn't mean that flexbility is not important. I hope it's quite clear that it's all about BALANCE. In other words, right vs. left, front vs. back balance (in both strength and flexibility) is what determines stability and thus possibly economy. The take home message is therefore to avoid random, indiscriminate stretching, because for all you know, you're messing up your natural balance, increasing injury risk and becoming less economical. But also, don't avoid stretching altogether, because then you might go the other way and get too tight in one important area! Everything in moderation!

Conclusion

So that's it for Part III, and the series. It's been a very interesting one, confirming the words of Carl Foster that running economy is a forgotten aspect of performance! It certainly seems that we have much to learn. The future of running research may be along the lines of the Tadese study that kicked off this series, and perhaps in a year or two, we'll understand much more what causes such remarkable running economy.

My personal feeling is that biomechanics, small calves and long legs aside, there is something critical that we can't quite measure. I am a big believer in the neuromuscular factors affecting performance. I believe that running economy is in fact a symptom of some underlying neuromuscular process or system that confers an advantage of certain runners. When you train, your neuromuscular system improves, you become more co-ordinated and your running economy improves, along with performance. But quite what this neuromuscular adaptation is (apart from the ones we've discussed) is not clear just yet. I feel it will go a long way to explaining the East African dominance in running and will also explain fatigue more comprehensively than any other theory.

So it's quite clear that we're not done with Running Economy! It will be back! We hope that this particular series has been interesting - we certainly haven't had the same debate, but it's a far less controversial topic than the muscle cramps and fluid ones!

Join us over the next few days as we scratch the surface of Baseball's Mitchell report and the report on Pistorius (which we hope is out soon)!

Ross

Running Economy Part II

The Biomechanics of Running Economy

Today sees Part II of our series on Running Economy. After spending the first two posts introducing the concepts and discussing the results from the Zersenay Tadese study, today we move onto some fundamental concepts of running economy - the physiology and biomechanics of running economy explained (partly, we hope!)

I say "fundamental" with some caution, because the more one digs into this particular topic, the more you realise that the science, and our knowledge of how to put running economy into practice, is still a long way off where it should be. I know that our good friend Amby Burfoot is fond of reminding us that science is actually a long way from understanding running physiology, and he's quite right. In the words of Sir Roger Banister, the first man to crack the 4-minute mile and who then went on to become a respected neurologist:

"The human body is centuries in advance of the physiologist, and can perform an integration of heart, lungs and muscles which is too complex for the scientist to analyse"

Running economy is one such 'integration". And with that in mind, let's get to it!

A fundamental paradigm - running economy: one of many explanations?

The first point that I have to make is that we should be careful not to over-emphasize the importance of running economy to performance. Yes, it is important. And yes, any coach, scientist or runner who is dedicated to training and improving performance needs to be aware of running economy and possible means to improve it. And yes, it has been relatively "forgotten" by science in recent times, hence our relatively limited understanding of it. But regular readers of The Science of Sport will also know that we're not particular fond of "magic potion", "silver bullet" training methods or science principles! So we must approach running economy for what it is - one of many explanations for performance.

So when we look at the East Africans, we note that they have a better running economy than the European runners. We also note that the best runners tend to be the most economical, that certain physiological characteristics predispose runners to be more economical, and that certain types of training improve running economy more than others (more on that in our next post, by the way). This is only partly relevant to you as you read this, because ultimately, you must not "lose sight of the wood for the trees", and become so stuck in the running economy analysis that you forget to worry about performance! And let running economy take care of itself...

Factors influencing running economy

Running economy, to repeat, is an integration of numerous systems and characteristics, biomechanical, and physiological factors. It would take a month of articles to cover all of them in detail, so we'll skim the list quite substantially, and discuss these three categories very broadly.

Biomechanical factors influencing running economy

The Zersenay Tadese article attributed his incredible running economy to the small size (and thus lighter weight) of his calves, compared to the European athletes. That is, he is carrying less weight at the extremities than they were, since his calf circumference was a good deal smaller than the Spanish runners he was compared to.

I suspect that this is only part of the answer, and possibly a very small part. As mentioned in Part I, Tadese's economy is much lower than the Kenyan runners tested before him, who probably do not have quite as much of a disadvantage as far as the calf muscle goes. So while the difference between Tadese and the Spanish might be calf-size related, there is more to it than just this.

According to an excellent review article from 2004 (by Saunders, published in Sports Medicine, 2004), the following biomechnical factors are important for running economy:

• Height: Slightly smaller than average is better for men, while slightly taller is better for women - I must confess that I don't have an explanation for the difference!
• Somatotype: Ectomorphic physique demonstrates best running economy. An ectomorph is generally long-limbed, thin, has shoulders that are about the same width as the hips! Think Paul Tergat, or just about any Kenyan long distance runner!
• Body fat: Low percentage, because body fat represents additional weight that must be carried, increasing the oxygen cost of running
• Leg morphology: Most of the weight distributed closer to the hips. In other words, if you have mass, carry it in the quads and not the calves! This agrees with the suggested reasons for Tadese's economy
• Pelvis: Narrow
• Feet: Smaller than average
• Shoes: Lightweight but well cushioned. There is evidence that cushioning improves running economy, possibly because it reduces the work required by the muscle to absorb and cushion the landing (that's the theory, anyway)
• Stride length: Freely chosen. This is interesting, because there is evidence from research that if you chop your stride to try to increase the cadence, your running economy worsens. We touched on this in our series on Pose running recently, and a lot of people find that they chop their stride when trying to use the method. According to the economy research, this would be undesirable. Having said that, if you are overstriding, then it's just as bad, if not worse, because a great deal of energy is lost in braking. This factor, perhaps more than any other, emphasizes that "Practice makes Perfect" and that running is a skill which must be practiced and learned. It happens naturally, yes, but it must be learned.
• Kinematics: A few things here - first of all, low vertical oscillation of the centre of mass. What does this mean? Well, it means don't waste time going up and down if you don't need to. The less you waste on vertical braking forces, the better. It was always rumoured that the most economical runners were effectively "rolling" their legs along beneath their hips - this is in fact a premise of Pose Running, as we discussed once before. There is nothing new to this at all (despite the fact that it was packaged as 'revolutionary', because we've known for a long time that a relatively flat trajectory is more economical.
• Secondly, minimal possible movement of the arms. That's not to say zero movement, because the arms play an important role in providing some rotational stability, but the movement must not be excessive. On this note, you see some absolutely bizarre arms carries among the elite runners, which you'd have thought would be corrected, but that only re-inforces that this is not an exact science.
• Third, a more acute knee angle during the swing phase. In other words, when your trail leg is coming through (eg. your right foot is planted on the ground and your left leg is catching up), then it's better to have that knee fully bent than straight. The reason for this is physics, relating to rotational torque and the force that is required of the muscles to bring the leg through. But the practical point is that the hamstrings come into play to reduce running economy, because they contribute to the flexing of the knee. One practical issue here is that when running slowly, it's almost impossible to bend the knee more than a few degrees - you'd be working so hard to bend your knee, the effect would be increasing your cost, not reducing it! So this is largely influenced by running speed.
  

Then there are a couple of other factors, which we'll touch on as we develop our discussions further in the next few posts.

But what is important to take out of the above list is that if you are a tall, skinny man, weighing next to nothing, with hips as wide as your shoulders, short arms, no body fat, and you wear a well-cushioned pair of size 6 shoes, you might have a good running economy!

The most important thing that jumps out from the above list is that there are some factors that one is born with (narrow pelvis, foot size, height, distribution of weight on the legs) and others that are improved with training and preparation, such as the kinematics like vertical oscillation and arm carry. Point is, great runners are born, and then trained. But everyone can run, and so as you read this, there is probably a great deal that you can do to improve your running economy, which would then translate into improved performance. But we'll discuss that in a separate post, later in the week.

Join us then!
Ross