“Ready to Run” Part 2: Flat Shoes and Foot Strike

Ok guys, grab a large cup of coffee and put your nerd glasses on….this post is a little heavy on the research.

Today I’m going to talk more about my experimentation with Kelly Starrett’s “Ready to Run”, in particular, about Standard 2: The importance of flat shoes (ICYMI, check out last week’s post for an intro to the experiment and my take on Standard 1). As you’ll find out, I don’t have much to say about how adopting this standard changed my running, but it DOES open the door for me to talk a little about running shoes and foot strike, two hotly debated topics in the running world.

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A little background: In the now-almost-classic studies coming out of Harvard University’s Department of Human Evolutionary Biology, researchers suggested a link between footstrike patterns and injury in runners. A 2012 retrospective study of middle and long distance collegiate track and cross country athletes found that the runners who utilized a rearfoot strike (“heel strike”) suffered TWICE the amount of repetitive stress injuries (distinct from traumatic injuries, which were not different between the groups). But, remember that correlation is not causation. The other things in this study that directly correlated with injury rates were gender, race distance, and miles run per week. So, yes, injury rate and foot strike are related….so are a lot of other things that you can’t really separate out here. In terms of footwear, A prospective study by Altman and Davis found no significant differences in injury rates between barefoot and shod runners, when the data was normalized for mileage (barefoot running group was older, more male-dominant, ran slower and ran less miles per week than the shod group).

barefoot runners.jpg

Taking it a step further, several other studies have looked at relationships between types of footwear, footstrike patterns, injury risk, and running economy. Another of Lieberman’s studies specifically looked at economy in minimal shoes and barefoot running vs conventional shoes. Runners were overall the LEAST economical in traditional, cushioned shoes. BUT, it’s  important to note that the study participants were runners who habitually ran either barefoot or in minimalist shoes….so of course they were more economical running the way they usually run?  Research should be taken with a grain of salt.

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On the other hand, it makes sense that shod runners in a cushioned shoe would have lower efficiency due to the stride characteristics they may adopt when shod.when you land with your foot out in front of your center of gravity, knee fully extended, it sort of acts like a brake; there’s a lot of shock that has to be absorbed and it takes a LOT of force to get you off the ground, especially since you’ve short-changed the elastic capacity of your Achilles tendon. BUT that begs the question: Is it the shoes? Is it the footstrike pattern? Or is it WHERE your foot is in relation to your center of mass? These are all things we need to control for when studying the relationship of shoe type to efficiency, in order to determine what effect the shoes have in and of themselves.

Other studies have shown that barefoot runners or runners in minimalist shoes tend to run with a faster cadence, and with more of a forefoot/midfoot striking pattern than a rearfoot pattern. You can then make the circumferential argument that barefoot running leads to lower injury rates or different injury patterns. But is it the barefootedness in and of itself? Or is it the cadence? Or the strike pattern? If you think about it, barefoot runners kind of HAVE to run with at least a midfoot strike, as the impact associated with heel striking would just be too painful to maintain. Traditional running shoes are built to cushion that impact….but if rearfoot striking really IS associated with increased injury risk, then are traditional shoes even doing their job? Minimalist shoes have made a big splash on the running market because they’re intended to mimic barefoot running….but several studies suggest that minimalist shoes actually don’t do a great job of mimicking the kinetics and kinematics of barefoot running. And check out this video from Chris Johnson: same runner, very different stride patterns in minimalist vs barefoot shoes.

So ummm……what does a runner even DO with all this conflicting evidence? What kind of shoes do you wear? Where do you put your foot when you run?

Kelly Starrett’s second standard of healthy running involves wearing neutral shoes – both in running AND around in your daily life (remember, it’s “building training into your day”) – to “allow your foot to be a foot”.

Full disclosure: I already run in zero drop shoes. My daily-life shoes consist of Keds, Sperry-Topsiders, and ballet flats. So….I can’t really say that Kelly’s second standard completely changed my running life because I was already doing it?

shopping

“So you run in zero-drop shoes…but you have a labral tear? you had to have surgery? So obviously this didn’t work for you!”  Well…. maybe, maybe not. For all the hot debate about shoes and footstrike in the running community, it’s really just one small part of a runner’s injury risk. This is why Kelly has TWELVE standards of being ready to run, not just one; and there are factors that influence injury risk that are not covered in this book!

Here’s what I think: Overall, if it ain’t broke…should we really fix it? The evidence is sort of equivocal as to whether asymptomatic faulty movement patterns (“DN” in the language of SFMA) influence future injury risk.  As for foot strike and shoe type, changing these variables will change the locations of injury, but not necessarily the amount or frequency – overall load seems to be more related to overall rate and risk of injury than anything else. If you’ve been running for 20 years in super-cushioned shoes and have never suffered an injury, why should you change your shoes? Further, if you’ve never suffered an injury and you’re happy with your performance, do we mess with running form? Foot strike? Cadence?

I don’t know the answer to that. The evidence seems to say a lot of different things about foot strike, shoe, type, and injury risk – science doesn’t really have a definitive answer.  So I think what it ultimately boils down to is the other 2/3 of what we call “Evidence Based Practice”: Clinical expertise, and patient values.

Evidence based medicine

I am not a clinical expert. I’m a first year student and I still get nightmares about my goniometry practical. It is not my place – yet –  to tell you what you should or should not do regarding your running shoes, your cadence, your footstrike, or your mechanics. What I AM going to tell you is that if you are having pain when running, you should visit a licensed physical therapist.

That said: Kelly Starrett is a clinical expert. He’s probably had a lot of success getting patients out of pain by transitioning to flat shoes, or changing their footstrike, or both! It seems to me like Kelly’s take on this whole thing is, wear shoes that “let your foot be a foot”. I love this idea. My college major was evolutionary biology, and while I disapprove of the phrase “our bodies are designed to….” (because evolution is a random process that happens without intent or design), I think it’s crazy cool that the structure of our bodies is so perfect for running in so many ways!

Let your foot be a foot. If you pronate or supinate too much, motion control shoes are probably not the answer – movement pattern correction and strength training are. And this goes both ways – minimal or zero-drop shoes are not likely to make a big impact on your foot mechanics the way barefoot running might (remember the above video). It’s really about getting shoes that allow your feet to exhibit the strength they already have, shoes that don’t squelch what your feet are so good at doing. Or what they CAN be good at doing with proper movement and strength training.

As for your foot strike? Well….the research is a little gray on this too. I am leaning towards the idea that it’s not so much which part of your foot touches down first, but WHERE it touches down, that matters. Striking too far in front of your body creates a “breaking” force. To overcome this and propel yourself forward requires excess energy, which hampers your running economy.   And of course, the increased ground reaction force will have to be absorbed higher up the chain, in your ankle, knee, hip, and spine….too much force can lead to problems.  This is part of the rationale behind the movement for faster cadence (more on that in a later post!) – higher cadence means shorter step length, which means less force with each footstrike and less shock absorption is needed up the chain.  Footstrike in and of itself may not be the problem -As Chris Johnson of ZerenPT says, “wouldn’t it be great if we could do all three [forefoot, midfoot, and heel strike patterns]?”.  Indeed, the repetitive nature of running is what makes runners so susceptible to injuries – perhaps injecting a little variety into the way we run – our stride, our footstrike – would actually be beneficial to our bodies.  But, again….if your mechanics are not causing you pain, problems, or performance deficit…do we mess with them?

If you’re a patient, or a clinical expert, then that’s for you to decide.

Stay Tuned! More on Kelly Starrett’s “Ready to Run” Standards: Jumping over to standards 9, 10, and 11: compression, hydration, and hot spots.

References: 

DAOUD, A. I., G. J. GEISSLER, F. WANG, J. SARETSKY, Y. A. DAOUD, and D. E. LIEBERMAN. Foot Strike and Injury Rates in Endurance Runners: A Retrospective Study. Med. Sci. Sports Exerc., Vol. 44, No. 7, pp. 1325–1334, 2012

Lieberman et. al. 2010. Foot strike patterns and collision forces in habitually barefoot vs shod runners. Nature 463, 531-535

PERL, D. P., A. I. DAOUD, and D. E. LIEBERMAN. Effects of Footwear and Strike Type on Running Economy. Med. Sci. Sports Exerc., Vol. 44, No. 7, pp. 1335–1343, 2012

 

Altman, A. and Irene S. Davis. Prospective Comparison of running injuries between shod and barefoot runners. British Journal of Sports Medicine 50: 476-480, 2016.

Boyer et. al. Select injury related variables are affected by stride length and foot strike style during running. American Journal of Sports Medicine 43: 2310-2317, 2015.

Almeida et al. Biomechanical differences of foot strike patterns during running: A systematic Review with meta analysis. Journal of Orthopedic and Sports Physical Therapy 45: 738-755, 2015.

 

 

 

 

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