Irene Davis Lecture on Running Shoes, Form, and Injuries: A Must Watch for Anyone Interested in the Minimalist/Barefoot Running Debate

Irene DavisLast night I came across a post on one of the Birthday Shoes forums that contained YouTube links to a lecture that Dr. Irene Davis gave earlier this year. Dr. Davis is one of the top researchers in the field of running biomechanics and an expert on the treatment of running injuries. She recently left the University of Delaware to become the head of the Spaulding National Running Center at Harvard Medical School. She is also a barefoot runner.

The presentation in the videos below is one of the best scientific overviews of the current state of knowledge on shoes, form and injury that I have seen, and Dr. Davis makes a strong case for why she believes that the modern running shoe is potentially a contributing factor to the high incidence of running injuries in modern society. The first audience member to ask a question in the Q&A calls it a “biomechanical tour de force” on this issue – I tend to agree, as my position is almost entirely aligned with that of Dr. Davis. If you have a free hour, the entire presentation is an absolute must watch.

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About Peter Larson

This post was authored by Peter Larson. Pete is a recovering academic who currently works as an exercise physiologist, running coach, and writer. He's also a father of three and a fanatical runner with a bit of a shoe obsession. In addition to writing and editing this site, he is co-author of the book Tread Lightly, and writes a personal blog called The Blogologist. Follow Pete on Twitter, Facebook, Google+, and via email.

Comments

  1. Thanks for another great post, Pete. 

    Re: Goatlips’ comments:  they made my day.  I can only equate him to George on Seinfeld.  He is way off base with his comments and tone, yet seemingly completely convinced that we are all complete morons.   Reading that actually made me even more sure that my move to running minimalism was the right one for me.

    While reading his post, I was imagining the corporate heads of Nike, Asics, Reebok, etc all composing those comments via a conference call with their lawyers and an otherwise out of work ad copywriter.

  2. Pete, thank you!  This is such a nice down-to-earth approach.  I think I will make all my patients watch this :)

  3. Goatlips says:

    There is no “debate” in my world.
    Some fool writes a book and it becomes a fad and trainer/shoe-makers cash in with ill-conceived gimmick designs based on the unproven theories.

    I’ve not read the books or even the internet debates (or watched these vids, LOL), but my view is:

    1. You can’t turn back human evolution – or improve it with a shoe, to any degree greater than they could 20yrs ago/at all. Anyone who thinks otherwise is naive. Feet are like hands – they barely change from training – they have virtually zero muscle or strength to develop.

    2. No shoe can really change your running gait – you’d have to do it deliberately…until you get tired a revert to type. And changing from your natural gait would probably do more harm than good anyway. Most running injuries are RSIs, which can be kept at bay with a proper, regular, stretching regime – not a quick touch of your toes before a run (a proper regime would actually mean NO stretching before a run – stretched musles are less energetic).

    3. Obviously, anyone who’s seen Oscar Pistorius run knows, for speed, trainers should be riged – to give you something to spring off, at the toe (your toes will NEVER be strong enough to do this naked!). And, to prevent injury, greater cushioning helps prevent bone/joint/spine wear. Perhaps if we ran barefoot we’d run softer – but only because of fear of treading on stones/glass/thorns/a glass marble/a half-eaten dog bone! But cushioning your foot strike with only your bare foot would cause metatarsals to eventually stress fracture – I rather let my big bone bare the brunt and not suffer a stubbed toe every 5 minutes.

    4. You’re extremely unlikely to improve at anything if you try to reinvent your natural technique. i.e. You’re almost certainly running in the most efficient style for your body/proportions/weight/spine/feet/physiology/muscles/muscle attachment sites, etc, even if you run badly. The best sportmen always keep the same technique until they retire.

    5. Some human feet and legs have evolved to become weak and puny. Some people are still robust. But in general, humans have evolved to need shoes even more than they need clothes! We’ve been wearing shoes for c.40,000 years!

    6. Humans aren’t meant to run. Pound for pound we are the worst in the whole animal kingdom! We are slow and unfit, get hernias and injured when we run – that’s just the way it is – get over it/yourself. We have 2 legs. If we’d evolved to run we’d still have 4 legs and paws, and go around sniffing each others arses.

    …Of course, none of the barefoot running idiots can have their topsy-turvy theories disproved because all people are different and therefore their ‘scientific’ delusions can’t be tested – which is probably a key design built in to their argument. 

    …I suppose some self-righteous bigot is going to make a cry-baby response numbered 1~6 now. But I won’t be reading it, I’m too bigotted to my own (correct) opinions….LOLlololol:

    • cody r. says:

      i’m almost speechless, but not entirely

      the feet and hands have a TON of muscles to be used and built up, 
      the running gait with shoes is NOT deliberate, it is attempting it as it naturally would, but the amount of cushioning and drop causes a change

      it’s just like how i think that if we wore gloves all the time, our hands would get weak, and our touch would be changed

      just quit trolling and get outta here

    • This post is too stupid to be believable. It looks like an obvious troll to me.

    • Get over yourself buddy, it ain’t personal against you.

    • Please don’t pollute this blog with stuff like this.  I won’t even try to correct everything you said that was completely wrong.

    • Pete Larson says:

      The level of ignorance displayed in this comment is astounding, and not
      worth taking the time to respond to. The fact that you openly admit to
      neither reading about these issue nor watching the posted video confirms
      this.

    • briderdt says:

      Of course there’s no debate in your world… You’re the only one there.

  4. Chris Szumigala says:

    One of the “related videos” on YouTube, a 9 minute interview, features some great comments as well. She gives props to McDougall, advocates for inclusion of clinical and research materials, and one of the most important principles of science… The truth changes…

  5. briderdt says:

    I haven’t watched much of the video yet, but so far the only thing I can say is this — GET A FRIGGIN’ TRIPOD!

    • Pete Larson says:

      I thought the same. It gets better. Seems maybe just an audience member filmed it.

    • Briderdt,

      it is a priveledge to see and hear Irene speak…folks travel across the globe for this.  I’ve taken frantic notes at her talks.  this is a beautiful film.

      Mark Cucuzzella MD

  6. Robert Osfield says:

    The two slides shown in Part 1: 6:00 and 7:00 show a couple of interesting attributes that Dr. Irene Davis does talk about but I believe are of interest in understanding changes to gaits and the attributes of different gaits.First up the slide at 6:00 “Impact Peaks and Loading rate reduced by 16-22%” does indeed illustrate how the runners on average reduced the impact peak – as discussed by Irene.  What I’d like bring attention to is that isn’t the only change on interest.  The after retraining curve is shifted after – the position of the peak loads is later in stance, and the loads later on stance are higher relative to the before results.Why is this of particular interest?  Well it shows after improving their gait they are running more balanced with much more even time on stance before and after the peak, and not front loading the stance, and… this means that they are landing with their Center of Gravity further back that they did before.  All too often we see it claimed that landing closer to the Center of Gravity is good thing, but here we have the exact opposite, those that land softly land with first contact point *further* ahead of their CoG as a measure of in time on stance.In terms of balance this is exactly what one would expect, so this finding is just fine from a mechanics point of view.  It does run counter to the popular gait cue though so worth thinking about.The slide that follows this, at 7:00 shows the differences between different foot-strike type.  Here we see the differences in loading rates and the classic impact peak of the heel strikers, with the midfoot and forefoot strikers close to illuminating this.  Irene highlights this aspect as again her for is on the first half of the stance. Looking further back to impact peak and we again see differences – the heel strikers have an impact peak that is earlier indicating that they are front loading their stance and landing nearing to their Center of Gravity as a ratio of time on stance.   The peaks for midfoot and forefoot strikers is later and much near to the center of time on stance – looking much more balanced either side of the peak.  What also jumps out is that the peak loads are substantially higher, and remain higher for the second half of time on stance.  From an efficiency standpoint a nice well balanced curve wins, but from a injury standpoint it’s an area one should look at for potential issues.  Given that Pete’s just published an article about stress fractures caused by loads after mid stance this may well be a significant finding.I’d like to come back to point about the distribution of loads across the stance, here we see data that tells as that the heel strikers are landing closer to their Center of Gravity, an earlier peak and to me suggests that they will be trailing their leg further behind them on push off.  From a horizontal equilibrium point of view this is what you’d need to do to compensate for the high peak of force when the foot is in front of the Centre of Gravity(Mass). While the midfoot and forefoot runners are landing further in front of their Center of Gravity but landing more softly so the horizontal forces won’t be higher, and with less backwards force their is less need to trail the leg, instead the foot comes off the ground earlier.  While the idea that heel strikers might create more horizontal forces is often cited as a reason not to heel strike, it’s not at all because their are landing further in front of Center of Gravity than midfoot/forefoot strikers, they aren’t at all, the non heel strikers are actually landing further in front of their Centre of Gravity but don’t pay a big penalty because they land much more softly, with the big forces only arising nearer to when the center of mass is over the foot.  This is important point to take home, it’s the heel strikers that are landing closer to Center of Gravity, so using this as cue is when changing form to a midfoot to forefoot strike is contrary to what actually happens with these gaits.I suspect what I’m saying here will be against the tide of runners that believe that landing close to the Center of Gravity will improve their gait.  They might even look back to pictures of heel strikers and midfoot and forefoot runners and observer overstridding in the heel strikers and nice vertical shins on landing for the non heel strikers. So how does this fit with the above findings? Easy, the mid foot and forefoot is in front of the heel by 6+ inches, if you draw the angles from the center of pressure on landing and the knee you’ll find that their lower leg has to be extended a long way to come close to how far in front you landing when not heel striking. When not heel striking you don’t need to over-stride to get a long stride, you simply put the front of your foot down first – you get the longer stride with no need to overstretch the lower leg.There is another takeaway from this second slide.  The high peaks in midfoot and forefoot suggest more force is generated over the same stance time so time in the air and stride length will be longer, or… a similar force is being generated over a shorter stance time for a similar time in the air (this data will be normalized in time on stance so you can straight away know what the time on stance was), either way this indicates to me that the time in air/time on stance is different.  Shorter time on stance would move the landing position and toe off position closer by an roughly equal amount towards the Center of Gravity as well, this will mean less horizontal force generated before and after mid stance, so one would expect this to be more efficient.  This shorter time on stance does come with a potential risk though – higher loads at mid and late stance is increases the risk on injury at these points.Or does it… Now these higher loads are the Ground Reaction Force measured on a ground mounted force plate, the forces that cause injury to bones and soft tissue are a different thing, yes related but all the same.  I haven’t seen any published or discussed data on this yet, but I suspect that midfoot and forefoot runners have lower knee flexion at mid stance than their heel striker counter parts.  If this is indeed the case then the torques generated at the knees and hips will be lower, and even perhaps the loads at the ankle might not be as high as you might otherwise expect.  My reason for suspecting that knee flexion is less is that the vertical oscillation of the Center of Gravity that occurs in response to Momentum, Gravity and the Vertical Ground Reaction Force on stance will be accommodated partially by the rotation of the foot on landing, so the knee doesn’t need to bend so much to match that curve that the upper body will be following.Another related point, and perhaps more profound, is that if there is a shorter time on stance without increasing the time in air (so has a higher cadence) then expect the curve itself to flatten, if the curve flattens the knee has to bend less to accommodate it.  This later relationship between cadence and the curve of the Center of Gravity and the need to a given amount of knee flexion is something that isn’t specific to any particular foot-strike type.Sorry for the long comment, just thought these observations might be useful for the debate.  This disucssion really needs a dedicated article with diagrams but alas I still a bit away from having time to write it all up more formally and starting a blog of my own.  One day… when I have a bit more time.

    • Joe Garland says:

      What’s your definition of “heel striker”?

    • Robert Osfield says:

      Sorry guys, last comment rather unreadable, there were paragraph breaks when I copy and pasted the text into browser but they disappeared on pressing commit :-|

  7. Joe Garland says:

    What I find interesting is that notwithstanding her being labeled the “Barefoot Doctor”, she recognizes the variety among runners and like you, Pete, and the others we had on RRT and Dan Lieberman understands that there is no magic solution that fits all. The far greater variety of shoes — I’ve taken to wearing the NB Minimi on my trail runs — available and the new ways of thinking about them and opportunity to provide help to those who suffer from injuries by wearing the “traditional” (albeit of only recent vintage) shoe is a boom to the participants in our sport.

    I also found interesting that she notes that we may have been born-to-run, but we weren’t meant to be doing long runs at sub-6 pace, but at 10 minutes. This little tidbit is immensely important in the debate. Since many of us run “unnatural” paces, it doesn’t follow that running “naturally” is optimal.

    Sadly, her use of data from the 2004 NYC Marathon (at 2:00, pt. 3) is misleading. First, I think she meant “18″; one must be 18 (not 17) to run that race (and the results show no 17 year-olds). Second, and more to the point, marathoners under 20 are rare, and rightfully so. One shouldn’t be doing that type of race until one has a fair bit of mileage under her belt. Plus the faster runners at that age aren’t doing them. They’re generally in school. Take a look at a NYRR results-page and you’ll see that. So the 18-19 age-group sample (70 males finished) is an aberration, as is clear simply by looking at the results). Here are the first 5 from 2004: 2:49 (19 y/o), 3:03 (18 y/o), 3:18, 3:27, 3:37. (For women: 3:38, 3:59, 4:13, 4:15, 4:34.) The first 64 year old: 3:18. First through fourth in 60-64: 2:54, 3:06, 3:09, 3:17. And her fastest 18 y/o and fastest 64 y/o is off by 15 minutes. 

    20-29? OK, lots of pros there. So 50th in that age-group: 2:47.

    The thing is that she need not use suspect data to make her point that running and racing is a lifelong endeavor and that, indeed, we were born to run. Take me. I’ve been racing for over 40 of my 54 years. Yet the fact is that I cannot race at anywhere near the paces at which I did my easy long runs when I was in my early 20s. 

    • Pete Larson says:

      Joe,

      Couple of things. I agree completely that variety is the key – options are
      more and more available, and if someone is running fine in a typical
      stability shoe, no real reason to change. But, I think Irene makes a good
      case as to why shoes like this can cause a problem for some people.

      Regarding pace – probably the biggest point of all, I also agree here. We
      run faster and longer than our bodies are probably meant to on a regular
      basis – perrsistence hunting is more of a slow paced run-walk. Goes for long
      distances, but certainly not 7:00 miles for 3 hours straight. In many ways,
      I think some version of the Galloway style of run-walking may be what our
      body best evolved to do. Run too fast, too long and race too often and you
      are bound to run into trouble, no matter what you put on your feet.

      Third – yes, not many sub-20 year old marathoners. However, I will say this.
      At my college some 40+ students run Boston every year, almost all of in the
      18-21 range. I have to admit that as the older professor, it gives me a hint
      of pride that my times compare pretty favorably with most of theirs! I also
      suspect that my best running years will be in my 40′s once my kids are grown
      and I have a bit more time to train. I think the point is that we can run
      well for a really long time as long as we stay injury free. That get’s to
      the point that running is something we humans are really, really good at.

      Thanks for chiming in as always Joe!

      Pete

    • Goatlips says:

      We were not “born to run”! Humans were born to farm! What is a human going to run after and catch – and what’s it going to do to kill it if it could? Nothing. We couldn’t even catch a squirrel. LOL! ;)

      …Also, it’s a myth teenagers are worse at marathon running than people over 30. I’m half crippled every day – I didn’t have a single ache when I was a teenager playing football from morning till night during school holidays. They’re just mentally weaker and give up and cry easily – Radcliffe-style. A one-off marathon of 3~4hrs isn’t going to do anything to a kid. I only get through my runs out of the aggression from  thinking of being a quitter if I stop – I enjoy developing my mental fortidude, if not my speed. Luckily, I never ran before 2009, so I’m fitter and faster than ever before! Yay! Go me! :)

      • Sorry bud, humans catch prey not by speed, but by endurance.  If you can keep, say, a deer at a gallop for a little while, it cannot sweat or cool during running, and will collapse eventually.  Please do your research next time, or don’t participate in this blog.  This blog is so good because of the level of intelligence by it’s readers.  We can have intelligent debates because we have done our research.  Pete takes the time to put truthful information in his blog, so the least you can do is become slightly informed.

        By the way: Were you running in cleats when playing football?  That might be the reason why you are crippled now.

        Also, i’m a teenager in high school.
        David

  8. “…as my position is almost entirely aligned with that of Dr. Davis.”

    Where is it not aligned? 

    Just finished watching the whole thing.  Very worthwhile, although nothing ‘new’, it’s a good summary of the argument.

  9. Hi, 

    Great summary video, thanks! 

    However, I got a bit confused. Recently Pete had a post featuring Dr. Casey Kerrigan. She stressed the importance of maximum load not the initial strike as a cause of running injuries, at least knee injuries. 

    Dr. Davis reports that injuries are associated with strike loading and barefoot running minimizes those loading. 

    So I don’t know two things: 1) which loading is causing which injuries and 2) which loading is minimized in barefoot running. Best,Maciej

    • Pete Larson says:

      This is a great question, and one that I asked Casey when I first suggested
      the idea of a post on stress fractures to her. After she explained it to me,
      I tried to boil it down in a reply to her to make sure I had things right.
      This is the way I interpreted what she was saying:

      “So, take an overstriding runner with a big heel strike and a nearly locked
      knee on contact (which modern shoes allow and perhaps even encourage). What
      you’re saying is that it’s not so much the initial impact that is the
      problem, but rather how the initial positioning of the leg sets things up in
      a negative way for the much larger forces at midstance. In other words, it’s
      things that happen downstream from the initial long stride and extended leg
      that are the big problem, but you can correct these indirectly by shortening
      stride. This then is the benefit for many who run barefoot/minimalist – they
      shorten their stride in such a way that they are better set to handle the
      higher forces at mid-stance. Am I following correctly?”

      Her response was “exactly!”

      For a tibial stress fracture, such as what Irene Davis was talking about, I
      can’t help but believe that impact shock plays a role. But, what Davis was
      saying was that they correlated impact loading rate with a higher incidence
      of injury. This is correlation, not causation. So, it could just be that a
      higher loading rate is in turn highly correlated with something bad that
      occurs at midstance, and the latter might be the real problem. This is the
      difficulty of coming to firm conlusions based on correlation studies.

      In either case though. shortening stride seem to mitigate the problem to
      some degree, which is really the important thing after all.

      If I had to bet, I’d guess that both impact shock and midstance forces have
      the potential to cause injuries, but the injuries would probably be of
      different types and in different spots.

      Pete

      • D. Casey Kerrigan, M.D. says:

        Pete,

        The real “a ha” moment for me came from a comprehensive
        analysis of what I was seeing clinically with what I was observing in the
        laboratory, combining force plate with motion analysis data (which remarkably
        had never been done before). The peak stresses and strains across
        virtually all common injury sites do not occur at impact but rather when the
        foot is fully planted around the time of midstance. I know this is a difficult
        concept for us to put our arms around as we all have been conditioned to think
        that impact transients are what cause injury (e.g. this concept is what the entire shoe
        industry has been based on). But in fact, the real stresses through common injury sites are determined by
        measuring the body weight force in relationship to the position of the bones
        and joints. Not only is the body weight force far more substantial around
        midstance, the position of that force in relationship to our bones and joints
        dictates to a tee where we get injuries, which are either compressive or
        tensile in nature. E.g., for the tibia, only at midstance is there any substantial
        compressive stress through the tibia and at that instant, the compressive
        stresses are far greater on the medial compared to the lateral aspect of the
        tibia. This is why we predominantly see tibial fractures on the medial rather
        than the lateral side of the bone. The same type analysis explains why we
        develop knee osteoarthritis on the medial, not lateral, side of the knee.

         

        I know this all goes very much against what we’ve always
        believed. Fortunately, when considering running form or running barefoot, per Mark’s point
        below, I think the distinction between impact and midstance is a rather moot
        point since the act of trying to hit the ground softly indirectly reduces the
        peak stresses at midstance. But the distinction was pivotal from my end in
        re-thinking a shoe midsole that could actually minimize (rather than increase!)
        these stresses.

        Casey

    • briderdt says:

      Likewise, we’re looking at the force transients at the tibia, and yet it would seem that much of the impact forces result in metatarsal stress fractures (shod and not).

    • Robert Osfield says:

      Hi Maciej,

      I also am curious about the what looks like two contridictory views on the major cause of running injuries – Dr. Davis asserting that is the landing phase, while Dr. Kerrigan asserting it’s around mid stance where at peak loads.  I suspect that difference will come from a focus on different injury groups.

      “So I don’t know two things: 1) which loading is causing which injuries and 2) which loading is minimized in barefoot running.”

      In terms of injury avoidance I think it makes sense to assume that loading rate, load at mid-stance and towards toe off are all important.  The great thing is that running with a good barefoot running form will reduce the loads on all of these phase of stance.  

      I read Dr. Kerrigan’s article as a clear warning that you shouldn’t ignore the loads at mid-stance and after as they bring their own risks, and while focusing of landing might sort out the impact peak, it won’t automatically sort out the mid-stance and after.

      Robert.

      • Robert,

        Absolutely correct…they both matter and barefoot running helps with both parameters. Folks need  not overthink this.  Land softly, be strong in midstance, and progress gradually.

        Mark Cucuzzella MD

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