THE first big study on barefoot running in Nature : Death to Heel striking

The barefoot debate is about to get a little bit hotter.

A new study to be released tommorow by Lieberman in Nature takes an evolutionary look at barefoot running. In the study, they compared barefoot and shoe running on a whole variety of factors in both regular shoe wearers, regular barefoot runners, and even Kenyans!

The study is entitled and I HIGHLY recommend it:
Foot strike patterns and collision forces in habitually barefoot versus shod runners

This is a timely piece as it adds more evidence to the article I wrote a couple days ago below (click here). The implications are great as they extend beyond barefoot running to foot strike too (heel vs. forefoot,etc.)I’ll highlight some of the findings.


Foot strike and Elastic response and energy transfer:

As I speculated in my article, footstrike greatly effects the elastic energy return. In their study, it was found that forefoot and some midfoot strikes “reduces the effective mass of the foot and converts some translational energy into rotational energy; the calf muscles control heel drop, and the FFS runner can take fuller advantage of elastic energy storage in both the Achilles tendon and the longitudinal arch of the foot.”
On this topic, Liberman speculates that the arch plays a key role in reduced oxygen cost of running in barefoot runners. Essentially during a mid/fore foot strike the arch can stretch over the entire first half of the stance phase, while during the rearfoot strike, it has to wait until the last part of this phase, thus decreasing energy storage and return.
Also, forefoot and some midfoot strikes allowed for greater energy transfer. When heel striking a large portion of kinetic energy dissipates. With forefoot striking, some of the translational kinetic energy converts into rotational energy.


Barefoot/Forefoot runners have a “smoother” ride: Difference in collision forces:


Barefoot runners “take shorter strides and to run with greater vertical leg and ankle compliance (the lowering of the body’s centre of mass relative to the force of the impact). This serves to blunt the transient force and results in a less jarring, ‘smoother ride’.” (Jungers, 2010)

Basically this means that because of the footstrike difference, the body uses the lower leg in a more efficient shock absorbing way. The foot is more plantar flexed and the ankle is more compliant. This creates a situation where the collision is essentially absorbed and spread out better.
In heel striking the collision forces are concentrated in one area, and very sudden. Meaning a large amount of force in one place, very quickly. Meanwhile in a more flat footstrike, as mentioned above, the impact is spread out, absorbed better, and not so sudden. This leads to peak vertical forces 3x lower in barefoot vs. shoe wearing runners and a rate of loading that is half as much for barefoot compared to shoe wearing runners

This difference may lead to injury prevention, as some studies have suggested that it’s not necessarily the total impact forces but the high rate of force in a very short time. (Look at the drawings in my article below and remember that barefoot running doesn’t have the initial peak impact force).  Still, the impact force debate can be VERY misleading.  Just a word of caution to read my other blog post on running shoes and realize that peak impact forces do not relate to injuries


Concrete vs. Dirt:

Another interesting finding is the adjustment of impact forces that occurs based on the ground you are going to strike. The study found that barefoot running produced less collision forces on a hard surface than a cushioned shoe.
Similar to the conclusions I came to in the Running shoe article(here), they found that leg stiffness was adjusted to control impact. This created a situation where there was no difference in rate or magnitude of impact loading based on the surface they were running on. As I have said many times, the body has a built in adjustment mechanism. It controls impact via adjustment of several different mechanisms.
So all those people who are worried about the impact forces of running barefoot on concrete should consider that when they stick a cushioning shoe on and heelstrike, there collision forces are higher!
Injuries:

In his accompanying article Jungers eloquently stated:

“Although there is no hard proof that running in shoes, especially hitech or PCECH (pronation control, elevated cushioned heel) versions, causes injuries, in my view there is no compelling evidence that it prevents them either10,11. However, there are data that implicate shoes more generally as a plausible source of some types of chronic foot problems12,13.”


Speed and footstrike:
One other interesting finding was that speed was NOT related to foot strike type or ankle and foot angles. That means, how fast the runner was in the study did not relate to how he struck the ground. That helps to get rid of the old argument that I have heard time and time again that footstrike depends solely on speed and that only fast runners strike midfoot because they run fast. WRONG.

From a range of runners running at speeds varying from about 7minutes per mile to ~4:20 per mile, footstrike didn't depend on speed.  Meaning that f

What causes heel strike?

“A major factor contributing to the predominance of RFS landings in shod runners is the cushioned sole of most modern running shoes, which is thickest below the heel, orienting the sole of the foot so as to have about 5u less dorsiflexion than does the sole of the shoe, and allowing a runner to RFS comfortably (Fig. 1). Thus, RFS runners who dorsiflex the ankle at impact have shoe soles that are more dorsiflexed relative to the ground, and FFS runners who plantarflex the ankle at impact have shoe soles that are flatter (less plantarflexed) relative to the ground, even when knee and ankle angles are not different.”
Evolution:

“Differences between RFS and FFS running make sense from an evolutionary perspective. If endurance running was an important behaviour before the invention of modern shoes, then natural selection is expected to have operated to lower the risk of injury and discomfort when barefoot or in minimal footwear.”
This essentially means, we’ve got millions of years of adjustment and fine tuning that went on to allow us to run barefoot with minimal risk. In addition, Lieberman points out several evolutionary changes that aid running. The development of the arch, which is essential for elastic energy return, is one of them.

Conclusion and Practical implications:

This study provides further evidence to some of the issues discussed previously in regards to barefoot running. For runners, the major implication could be on foot strike. It’s more than just barefoot running, it’s footstrike that matters. A lot of the differences in collision force are due to footstrike variations. For years, shoe companies and others have said that heel striking is the way to go. Elite runner Mark Plaatjes even made the same argument earlier this week in a well written paper. Lieberman’s article helps lend credence to what I and many others have always speculated. It’s not.

The human body was designed to run with a forefoot/midfoot strike and shoes cause us to run barefoot. In one of the nature barefoot articles there is a great picture illustrating this (Picture can be found here). It is of 2 Kenyan boys running on a dirt road. One is barefoot and landing whole foot, one in shoes, slamming his heel into the ground first.  Shoes decrease proprioception, change ankle kinematics and allow the body to change it's landing habits. 

Therefore, the major finding is that footstrike may be more important than running barefoot or not.  Granted running midfoot is hard with heavy shoes.  The study shows that footstrike was what mattered.  Barefoot runners who landed heel first still had much higher impact forces than when striking forefoot/midfoot. Similarly, the rate of loading was still much higher in barefoot heel strikers than barefoot forefoot strikers. This finding that footstrike matters is something that track coaches have been saying for decades.  One of my big mentors, Tom Tellez, has been preaching this for a long time.

More focus should be focused on changing footstrike with barefoot/minimalist running used as a way to aid that change. 

A change to barefoot running should be accompanied by a change in running style to a midfoot/wholefoot/forefoot one.  For information on how you should run read this (here) and watch these (here and here) (no I don't think Pose or Chi are wonderfull...)

Lastly, I think the take away message is that the human body is more complex than we give it credit for. The fact that it alters footstrike and pre-activation and numerous other mechanisms based on what is on the shoe or what ground you are going to strike is amazing. Think about that for a second. A couple years back Adidas tried to sell a shoe with an expensive microchip that adjusted cushioning each stride. The shoe cost several hundred dollars. The problem is, we already have a mechanism that does that for free….ourselves!

Lastly, a word of caution.  This study will catch on fire.  The major newsgrabbing headline will be the impact forces.  However, that is likely a gross oversimplification of the process.  Like with other variables (VO2max, lactate,etc.) don't get tied to one while missing the big picture.


If you enjoyed this or any other article, please help get the information out there and pass it on. Much appreciated.

To read more about barefoot running and running shoes read the below article on Why Running shoes do not work:
http://stevemagness.blogspot.com/2010/01/why-running-shoes-do-not-work-looking.html
POST A COMMENT

I'll leave you with a wonderful video of barefoot forefoot striking from Dr. Lieberman:

23 comments:

  1. While there is plenty to think about in this study, I can't help but think of the missing pieces.

    The one factor that is consistently left out of the footstrike debate is speed. There have been a few studies of elite athlete but none about the average runner. (I think I am safe in believing speed is relative.)

    I think it is reasonable to most runner to plod around without shoes. But there many runners who train at a variety of paces for a variety of distances in search of a PR. Is mid-strike best for every pace? Is heel-strike always "bad"?

    Perhaps you could shed some light based on your experiences- assuming you do work at various paces.

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  2. Steve, you have a great blog, keep up the good work!

    Prof. Lieberman has also created a website to explain and popularize his research:

    http://barefootrunning.fas.harvard.edu/

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  3. To DumpRunner Matt, Steve does talk about pace. He states the study had runners from 7:00 per mile to 4:20. From my own experience, it is terribly difficult to run really fast as a RFS'er. Therefore we can make the conclusion that FFS is best for fast speeds, then combine this with the findings from Dr. Lieberman's research and I'm even more convinced now than I was before that FFS is best for all running speeds.

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  4. Thanks Coach. Somehow I completely missed that paragraph.

    I am wondering how FS changes in an individual during different paces. I was always taught in track when sprinting to "get on my toes" which was atypical for most of my running. Perhaps there is no relevance to the study but I think one's footstrike is not set in stone at every pace for that individual.

    I also also seen some studies when show that sensory feedback is reduced at higher speeds.

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  5. Kevin1:06 AM

    in the video is the kid doing what you consider toe off?

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  6. Steve, keep writing great articles dude! My friend Dustin and I have been running about half to one mile barefoot strides at the end of our runs lately. Apparently this is something he learned while running at UTA, I must say it is quite fun and a great way to end a workout. Thanks for keeping it real.

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  7. I'd like to know more about why you don't think Pose Method and Chi Running are wonderful. I can concede that they aren't the bee's knees, but after taking a lot of time off from running due to injury, I picked up the Chi Running book and while I don't agree with all of it (I think the book is about 8 times longer than it needs to be and there is a bit of hooey), if nothing else, it got me thinking about my form and mid-foot striking.

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  8. First of all, as I mentioned in a comment on a previous post, the saturated fat/cholesterol story is very nicely discussed in a recent posting by Dr. Eades. see http://www.proteinpower.com/drmike/cardiovascular-disease/saturated-fat-and-heart-disease-studies-old-and-new

    As for barefoot running, see this post (and related links) for discussion of the Brooks and Runner's World reaction to barefoot running. They are certainly not embracing it wholeheartedly. http://www.runningandrambling.com/2010/01/brooks-ceo-jim-weber-on-barefoot.html

    My husband ran a 50K last weekend in his vibram five fingers (I wore Brooks). He got fewer blisters than I did (one versus three)!

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  9. DumpRunner Matt-
    I think speed plays a slight factor but it’s a misnomer. The fact is runners who strike forefoot do so at almost every speed. The runners who heel strike do so at the majority of speeds too. I’ve even seen heel strikers sprint while heel striking. Yes, it will shift slightly based on sprinting, but you don’t “get on your toes” when sprinting. You forefoot strike, and with most the heel drops down too.
    There will obviously be a speed at which we heel strike like in walking, but my guess is that it is a very slow speed. That speed where it’s just too fast to walk but not fast enough to jog.



    Tuck-Thanks for the link. Excellent site

    Kevin- No, watch the end of the foot during the push off. You can tell he’s not because you don’t get a huge pushoff at the end from the toes. It’s tough to explain in words, but watch that last part over and over and you’ll see that he’s not trying to get anymore push off at the very end.

    Jgoreham- That’s another post entirely! Chi and Pose both have very good things about them in particular the footstrike. My main complains are with other components. They are not entirely correct biomechanically. There’s just a couple things in each that I disagree with, in Pose for example I don’t agree with the hamstring pull. The recovery mechanics are the result of hip extension putting a stretch reflex on the hip causing the recovery leg to cycle through. I’m not a fan of actively trying to pull it through. As you said though, the good thing is both get you to midfoot strike which for most people not concerned with speed, is the most important thing.

    Cynthia- Thanks for posting the link. I’m going to take a look at it. Congrats to your husband! 50k in vibrams is impressive! I’d love to hear how he built up to being able to do that.

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  10. Kevin2:04 PM

    Concrete vs. Dirt:

    so that section is implying that is possible to transition to minimalism on concrete because your body adjusts to impact forces correct?

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  11. Another post re industry response- this time fearmongering!

    http://www.runningandrambling.com/2010/01/declaration-of-dependence.html

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  12. I hope you'll write that Pose Method and Chi Running blog post sometime, I'd love to read it :)

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  13. This post and the previous one on shoes has me wondering. I'm not likely to switch to barefoot running -- Nairobi roads, where I currently run, are definitely feet-unfriendly.

    I'm a moderate over-pronator and have been using stability-control shoes (Etonic Jepara SC). Based on this recent research, would switching to racing flats for my training be a good (wise) move? Lighter weight, less heel cushioning, lower to the ground, etc.?

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  14. Steve,
    I am sure you are aware: ChiRunning has a completely different leg motion from Pose. ChiRunning does not actively pull the ankle to the butt or bring the leg through. The knees bend while keeping them low.

    Thanks for the post/blog resource.

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  15. Shilingi-Moja-
    I'd say that switching to racing flats on SOME runs to start with would be a good idea. Remember that you've been running in a certain way with similar shoes for a long time. So, the transition has to be gradual.

    eChiFitness- Thanks for pointing that out. I knew that and didn't mean to implicate Chi running with that Pose idea.

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  16. I have now posted a new blog entry on my experience with progressively longer running in Five Fingers over the last eight months and 1200 miles. There’s no real magic, just steady increase in distance and difficulty as with any other training. I didn’t attempt a 50K until I was confident I was ready. —David

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  17. Anonymous9:27 PM

    All quite interesting but hardly conclusive regarding whether or not attempting a change in running form is a smart choice.

    Will anyone ever attempt a long term study with actual running subjects with full control groups etc. to try and determine if runners can become faster by changing foot strike?

    Impact studies are cute but perhaps are quite misleading when you consider most elite marathoners run heel toe. If anyone has become an efficient runner over time I would think it is most likely the marathoner.

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  18. Anonymous5:23 PM

    @Anonymous
    I'm not an expert, but I believe that most elite marathoners do not heel strike.

    Two notes: most shoes have a higher platform under the heel than the forefoot, so a video of a shod runner may be deceiving.
    Also, I believe the difference between RFS and FFS isn't what touches the ground first, but what absorbs the force of landing. See the following:
    http://www.youtube.com/watch?v=hsUfo_jHQ60

    As an aside, I used to be a prominent heel striker and have successfully moved my strike forward on the foot. I feel that it has been an important part of my improvement over the last year or so.

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  19. @ Anonymous

    I watched some of the Berlin marathon this weekend, and I didn't see any of the top 10 runners heel striking. They all struck midfoot/forefoot.

    I do think it'd be interesting if someone undertook a real long-term study though. Problem is, there are so many variables that it'll be difficult to put the findings down to any one particular cause.

    Steve, maybe there's a PhD in there somewhere? :)

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  20. Anonymous4:13 PM

    The Harvard study that is being referred to was funded in part by Vibram.

    I'm not drawing any particular conclusions about barefoot running (I think more science is needed for that) but it's important to question studies where there's a conflict of interest with the organization that funded it.

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  21. This comment has been removed by the author.

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  22. Anonymous3:08 PM

    As an avid runner and marathoner I've always had an interest in the biomechanics of running, in particular my own gait! After two back to marathons I began having difficulties with IT bands and knees, though I was focused on strengthening, stretching and rolling. It provided relief to a point, but after a certain mileage no matter what I did I'd eventually hobble back.

    I was intrigued by Dr. Lieberman's site and decided to transition to FFS. After less than two weeks my IT band and knee issues resolved, though I set myself back by improperly running in toe gloves inadvertently fracturing my heel. I've comfortably transitioned to FFS, my IT and knee issues have not returned, I find I'm able to run longer with less fatigue, and feel I recover more quickly.

    Only time will tell if I remain injury free as I ramp up the mileage and run races in the FFS mode. I'm hopeful and excited.... :)

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  23. Great article.
    I'm a mediocre runner,a few miles most lunchtimes and also short and quite stocky.
    I recently switched to 5 fingers and after a gentle period of learning to run again, i'm a convert.

    I seem to be running better than i ever have and was trying to work out why. ( faster times, very consistent pace, better breathing and generally having more fun).

    Some of this may be "psychosomatic" due to new shoes and paying more attention than i used to, but, I had noticed the “take shorter strides and to run with greater vertical leg and ankle compliance . .... results in a less jarring, ‘smoother ride’.”
    I also think that the "lowering of the body’s centre of mass" gives me a more stable, natural running style, as i am not the right shape to stride out.

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