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Wednesday, March 17, 2010

Barefoot running and shoes Q & A Part 3

Barefoot running and shoes - the Q & A Part 3

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Ross

19 Comments:

Kevin said...

Your timings with these posts are perfect. I began running six years ago. I was 170 pounds and the shoe salesman put me in Brooks Beast, which is Brooks' heaviest stability shoe. As I became more efficient, I had hip pain and they changed me to Adrenalines. Recently, I began having hip problems again. (I'm 150 pounds now and even much more of an efficient runner) and changed to a Brooks neutral shoe. I was hesitant to go neutral because I have flat feet, but I've done about 100 miles in Etonics and Brooks neutral shoes and have felt great and my feet no longer feel like I'm fighting my shoes. Its like my brain can now activate all the muscles in my legs to run now. Weird? I know. Looking forward to your next post on this subject.

Colenso said...

I'd just like to make a small comment on the history of the modern running shoe, Ross.

In the UK, the modern running shoe first became available in the autumn of 1976. It was made by Puma. I know because I was one of the first junior runners in Oxfordshire to acquire a pair. No one else had them. And until they did, it gave me quite an edge in road races and in cross country on the hard surface sections, I can tell you.

Perhaps in the US, or in South Africa, such shoes were available all of six years earlier but if that were indeed the case then I would be extremely surprised.

Ross Tucker and Jonathan Dugas said...

Hi Colenso

Thanks for the info. I was lucky enough to see Tim Noakes' shoe collection - he kept his shoes over the years, and there was indeed a marked change in design of the shoe around the latter part of the 1970s. That co-incided with the running "boom" in the USA, which I gather drove this revolution. It shortly preceded the Nike explosion, and the devices like air and gels followed shortly after.

I did say in the post that the explosion in the industry happened in the 1970s, which fits with your account.

I'd be guessing at the exact date, but I remember his shoes from Comrades in 1970s were distinctly different from what he wore in about 1975, when suddenly the thickness of the heel increased enormously.

Regards
Ross

James said...

Hi Ross, I have been coaching running (for triathlon) for 15 years now and one of the first things I do when people come to me is get them running barefoot. With a little coaching on the mechanics, their pre and post run video is dramatically different and they always comment on how the “look like a runner now”.

Recently, I have been running in five-finger and after running on my forefoot for years, I could not believe how much strength I was lacking in my lower limbs to execute barefoot running well during a track session. The same session (and only the first 4miles of 10 in five fingers) I have done for the past few months left me very sore. Interestingly during the run, my HR was around 6/ 10 bpm lower than the previous session (surly this study would be passed in most of today’s journals!) and I was able to hold a much higher strike rate.

The plyometric type nature of the muscles and tendons in action over the thousands and thousands of repeated steps of any run, shows me we need to be very strong to run well. Moreover, in this more “natural” running way, you would be very hard pushed to find the old heel striker willing to thud their heel into a hard surface.

An article I recently wrote on running can be found here

http://www.tri247.com/article_6461_Performance+Running%3A+No+two+ways.html?region_id=&category=run

Nicholas Finch said...

As a barefoot convert I am reading these posts with interest and notice that, despite your scientific approach, you then use opionion, rather than fact to avoid taking a standard. It is clear that the case for barefoot running and against shoes is overwhelming yet you quote: "This man, straight into a lightweight pair of shoes, would not be a runner, I have no doubt about this, and so it would be false to say that shoes don’t help at least some of the time'
Is their any scientific evidence of this or just personal opinion. As a respected scientist I would have expected better.

Tuck said...

"However, and this is the side that none of the barefoot advocates wish to hear, part of the reason we believe shoes help prevent injury is that it’s possible that shoes DO prevent injury, or at the very least enable people to start running!"

Well, I certainly consider myself an advocate of barefoot-style running. I will nevertheless surprise you by agreeing (mostly) with this statement, and also point out that a lot of the other barefoot-style runners I know will also agree (mostly) with this statement.

But what I think you're missing is that running shoes make running easier by allowing you to run beyond the capabilities of your feet. This is something that virtually all of us who try to take up barefoot-style running run into. The feet are not required to do as much work running shod, even in real minimalist shoes (even in Vibrams).

One will discover when transitioning from sneakers to Vibrams (I'm 8 months into it) that every muscle involved in running from the ribcage down needs to get stronger. This starts with the calves, but works through the feet, the knees, and ultimately the lower back and abdomen. I was quite surprised to come back from a run and discover that my lower back was killing me! Fortunately this was merely muscle fatigue.

My theory is that imbalances between the muscles used in running in sneakers and the muscles unstressed when running in sneakers are the cause of a lot of running injuries, and a lot of others are simply a function of heel striking.

Basically, sneakers allow you to run beyond what you're really physically capable of.

We refer to an "injury deficit", similar to the "oxygen deficit" of anaerobic running, where you're able to run to a point past what you're capable of doing, injury is the logical result.

Anonymous said...

Great series. I notice the weight difference when running barefoot as opposed to shod. Please comment on these studies showing an economy benefit when running barefoot. Thanks. Mike

"Barefoot Running: A Natural Step for the Endurance Athlete", Dennis G. Driscoll (August 2003)
http://web.archive.org/web/20040626060315/http://nhscc.home.comcast.net/l3_paper.htm

"Finally, how does running economy compare between the barefoot and shod state? Oxygen consumption has been shown to be 4.7% higher while wearing shoes (approximately 700 g per pair) and running at 12 km/h.20 Reasons for this include the mass of the added footwear requiring additional energy to move the shoes through each stride, energy being absorbed by the shoe’s cushioning, and the energy expense of flexing the sole of the shoe. When these energy drags are combined with the previously detailed loss of a stretch reflex from the lower leg it becomes understandable that barefoot running is more economical."

The above references this study:
Warburton, Michael. "Barefoot Running." Sportscience, 5.3(2001), .

"Laboratory studies show that the energy cost of
running is reduced by about 4% when the feet are not shod".

Matt said...

What Tuck said makes a lot of sense. I've been running barefoot for a few years now, and my feet, especially at first, kept me in check. But this is a good thing. One of the things about running is that it can be very challenging to be patient when starting out.

I still find minimalist shoes to be helpful for Winter running. I don't have any intentions of getting frostbite.

Boris Hornbei said...

Hm, seems like a case of reason controverting experience, to a degree. I've run for about 40 years and I've consistently found that wearing "neutral" shoes leads to severe knee pain that prevents me from running, whereas "stability" shoes don't.

Douglas Kretzmann said...

I started running in 1974. I got my first running injury from running on the roads in tennis shoes, a nice little neuroma which still irks me today. The second running injury came from the first pair of 'real' running shoes I owned, Adidas Safari, also in 1974. They had a thick sole, high heel, great cushion and light weight: but the heel compressed very quickly so it actively encouraged overpronation, which rapidly resulted in runner's knee.

For the next few years I stuck with the minimalist shoes such as Adidas Rom, Onitsuka Tiger flats, etc. The injuries came and went. For a year I ran barefoot, even on the roads. To me it was impossible to race shoeless though: at that effort level I could not sustain the level of attention needed to keep from hurting my feet on gravel, glass, kerbs etc.

I am very grateful for the excellent running shoes that are available today. Those 70s shoes were horrible: first the minimalist ones that offered no cushion and generated impact injuries; then the massively overbuilt horrors like the Nike LDV which looked to me like a knee injury in a box. Tom Osler, in the Serious Runner's Handbook, had an entire chapter on how to rebuild the Onitsuka Tigers to make them suitable for ultrarunning. I remember Adidas' top-of-the-line marathon shoe in the 70s, called the Marathon oddly enough - a quarter inch of hard rubber in the heel, an eighth in front. Gave a tooth-jarring ride, it hurt just to look at it - only the biomechanically elite could do so without sustaining an injury.

Uli said...

"Take a 100kg (220 lbs) man who wants to take up running. [...] This man, straight into a lightweight pair of shoes, would not be a runner, I have no doubt about this, and so it would be false to say that shoes don’t help at least some of the time."

What makes you certain about that? If he would only have light shoes as an option he would maybe start running more conservative, progress in a healthier way and maybe stay a runner beyond just finishing a marathon in a ticked- off-next-please way?

MichaelMc said...

I'm sure running companies would say "(shoes) allowing you to run beyond what you are physically capable of (barefoot)" is EXACTLY what they are trying to accomplish.

I think this may actually touch closely on the hidden truth. Cushioned shoes ALLOW (not neccessarily REQUIRE) a less adept landing. In the short term this allows runners to train harder, but the lack of 'feedback' may hinder development in the long term. You could liken it to a brace: it can allow you to do things you couldn't otherwise but might hinder you from developing the strength to do without.

A lot of this debate seems to come from people who are not focused on peak performance, because the transition methods employed don't suit maintaining training. There seems to be an emphasis on switching as soon as possible, rather than gradually strengthening all the tissues WHILE STILL TRAINING HARD. From personal experience I feel there is a lot to be gained from WALKING AROUND barefoot, as a preliminary stage, while maintaining running shod. Runners who obsessively plan their training to work on each different energy system suddenly drop mileage and "leap" into minimalist shoes, even at the cost of aches/pains/injuries. Odd.

As far as the running economy argument goes, lets be realistic: a 4.7% difference is HUGE and competitive runners could not afford to run with such a deficit, regardless of sponsorship. The top marathoners do NOT run barefoot, so there logically cannot be that kind of handicap attached to shoes.

Tim Butterfield said...

Take a 100kg (220 lbs) man who wants to take up running. [...] This man, straight into a lightweight pair of shoes, would not be a runner, I have no doubt about this, and so it would be false to say that shoes don’t help at least some of the time."

When I started the Couch to 5K running plan last year, I weighed 237 lbs and had been mostly inactive for over twenty years. I started C25K using Vibram FiveFingers. The biggest issue I had with footwear was the need to stretch my calves/achilles due to the shortening from wearing shoes with raised heels for everyday use. Progressing gently through the C25K resolved that on its own.

After decades of inactivity, the much bigger issue was lack of aerobic fitness. Later in the C25K workouts, my HR would regularly hit 165-170 bpm, much too high for a 45 year old former couch potato. After completing the C25K, I switched to some low HR training (Maffetone) to better build an aerobic base.

If you progress sensibly and do not do 'too much, too soon', an overweight inactive person can do just fine with minimalist footwear. Or, they can even add in some barefoot as I did. In hindsight, I wish I had started with barefoot even sooner. I think going barefoot is one of the best way to dial in good form as your feet can tell you what you are doing wrong.

Harry Hollines said...

The position that "it's possible that shoes DO prevent injury . . . ," could be true and I'm a proponent of barefoot and minimalist running. However, the question is whether that'a good thing, that is, if you are over-weight and/or have weak feet, should you jump straight into running a lot of miles or, instead, start slowly and get into shape and run a few block and build up slowly. We live in a "results now" society as opposed to looking at the long term and improving gradually. Additionally, weak feet is a major issue and shoe just hide that fact but eventually it catches up with you, hence, the 60%+ injury rate. This is akin to football players that take shots/drugs to play on Sunday. Well, they can play so you can argue the drug help although the player is further destroying their body. Shoes may help people run today but what about tomorrow. The legendary Gordon Pirie said one of the most important aspects of running is the connection with the feet and the feet must be strong. He also mentioned that the East Africans generate power from their "feet" and we (Americans/Europeans) generate power from our "legs," and that this is a major reason for our injuries and lack of speed in comparison.

So my point is if you are weak, over-weight, out of shape, etc., is it better to address the core issue or hide the problem and continue?

If you just want to run 1 race in your life, then this isn't a big deal but if you want to run for many years or for the rest of your life, then I'd recommend a different approach.

Harry Hollines

Ross Tucker and Jonathan Dugas said...

Hi folks

Thanks for the discussion - all very stimulating and too large to do justice to.

Just a couple of replies:

To Nicholas Finch:

I must just point out that your opinion is also just that, an opinion. You've accused me of having an opinion - I'd say it's more of a stance adopted based on the sum of all the evidence. This post has specifically looked at shoes, and so taken in isolation, it would oppose the view that shoes are good for you or required. However, the collection of evidence does little to support that people should be aiming to run barefoot, particularly right away.

And if you stick to the context of my argument, which is only fair, then you'll see that I am very specifically advocating for shoes in the case of a beginner runner, not all. My actual position will become clearer as I move through all the evidence, not just this one post.

However, the key point is that you need to assess how your own "opinion" is created. You'll find that it's the same as me, but that you lack evidence just as much as you're accusing me of lacking.

The difference is that you're a barefoot convert, so you've decided based on your self-experiment. Again, I've repeated this before - there is a lot of merit in barefoot running and it will be effective for a good many people. But not all, and you're making the same error as you no doubt accuse shoe advocates of making.

In fact, Douglas' testimony points to this, Nicholas. His experience seems opposed to yours, yet there it is. THe only case we've had so far of someone who shares the opposite experience. As I said, people who give their experiences in this debate tend to be those who've succeeded - there are many other Douglases out there, I have no doubt. Opinion yes, but not a shot in the dark.

To Tuck:

That's a really good point, and you're pre-empting an argument that I was actually going to explore later in this week about how shoes allow higher training volumes than would otherwise be the case. This is a very important, and good point in the argument, you're 100% right.

And then finally, to anonymous:

Fair point - that reduction in economy has been almost entirely linked to a reduction in mass though. I do believe that studies have been done looking at barefoot running with similar weights on the feet, and found no difference as a result of being barefoot. So it's a mass effect, which is very important for the elite runner.

Then to Harry, Tim and others re the 100kg man example:

You all make fair points, and of course this may well be true. I've seen runners through our Optifit programme at SSISA, which aims to take people to their first 10km and they really battle, sometimes regardless of the shoe they wear. I think again, it's not wise to generalize, and perhaps I made that error in my analogy. There will undoubtedly be guys who do succeed in lightweight shoes or Vibrams, or barefoot, just as there will be guys who fail and blow out Achilles tendons.

This will, I believe, happen across the range of weights, but is far less likely in the 60kg runner than the 100kg runner.

So as for most situations, I think the individual determines the outcome, but you're all quite right, including MichaelMc, who makes the point about the timing. Harry, I think it agrees that short term, the shoes then benefit. Long term, I also agree that this person could well look at moving lighter.

But again, in the absence of the evidence for this position, I'm still going to lean conservatively and say that it depends on the person!

Ross

Colenso said...

Ok, let's cut to the chase. How many runners have run a sub 4-minute mile barefoot? Or a sub 2:10 marathon barefoot?

I'm all for barefoot running. Indeed, these days I run barefoot exclusively as I've made clear in my previous posts. But there is no way in the world I would have a chance of winning a road race at local level running barefoot, even in my age category, let along over all. I would have to wear light weight racing shoes for the race.

Now, perhaps if I got my BMI down to Gebrselassie's, that would change matters somewhat. But while my BMI's around 25 or so, then I simply can’t run close to 3 mins per km pace over 5 ks on tarmac barefoot without injury, whatever style I adopt. The average impact forces on my feet, lower torso and spinal column; the peak impact forces; and perhaps most importantly, the torques (which can’t be measured directly with a force plate), exerted on the critical parts of my structural components are just too great. And I don't need to record my force data on a force plate running at 3 minute ks to know this. After forty five years of fairly successful competition over every distance from the 8O metre high hurdles as a youngster to the marathon as an adult, I believe I know a fair bit about what my body will and won't cope with.

Sure, I say, along with Ross, go Barefoot Running! Indeed. Nevertheless, in a nutshell, for me barefoot running is not ever going to be the same as barefoot racing and no amount of technique modification is likely to alter that for me, unless, as I say, I dramatically reduced my BMI.

Rochrunner said...

Anyone who thinks the body doesn't know how & when to automatically cushion impact just has to think back to the last time they thought they were at the bottom of the stairs, but there was one step to go. You can feel that jolt all the way to the top of your head!

D. Isaiah said...

Colenso, I think you make a good point for the wrong reason. There aren't runners out there posting sub-4s or sub-2:10s in the mile or marathon, but it certainly isn't because of the impact forces and torques. In fact, if science has shown anything about barefoot running for sure, it is precisely that impact forces and peak torques are attenuated more efficiently when unshod!

(See "The Effect of Running Shoes on Lower Extremity Joint Torques" by Kerrigan, et al. for the torque question, and the oft-cited Lieberman, et al. for the impact transient.)

I would claim that the reason there are no 2:10 marathoners running barefoot today is simply a question of foot toughness. As many have pointed out in these comments, running barefoot strongly limits total training volume in the early stages, simply because of the foot conditioning. I have personally run my feet to bleeding in multiple 5k runs, when in shoes I would have run much farther. I can never progress in running volume beyond my foot toughness.

Now, it is probably true that overall foot toughness can never be increased high enough to run a 2:10 marathon, because the soles of your feet will never be rubber. Of course, this doesn't counter the claims of the barefooters, it merely demonstrates that once you become very competitive, you can push the envelope of your running ability by doing some of your running in lightweight shoes.

This, of course is 100% aligned with the way the Kenyans in point of fact do train over a lifetime. They get very, very efficient barefoot; once they become very competitive, they put shoes on and manage to surpass what the human body would be able to do on its own. (Probably no 2:10 marathoners in Paleolithic Africa, either!)

But it's also 100% in opposition to the point Ross makes about a heavy person, or beginner runner. In both my research and personal experience, I've seen evidence that shoes can have benefit, but almost certainly not by enabling a beginner runner to "unnaturally" run beyond his muscular resiliency or foot condition! Indeed, you would expect just the opposite to be the case: much, much safer to start out barefoot, and end up in shoes.

Jen Sinkler said...

Hi, Ross -- I'd love to do a brief interview with you on this topic for the health and fitness magazine Experience Life (www.experiencelifemag.com). Can you drop me a line at jsinkler@experiencelifemag.com as soon as you get this? (Sorry to leave this in the comments, apparently I wasn't bright enough to find a "contact us" link anywhere on the site.) :)
Jen Sinkler, senior fitness editor, Experience Life magazine