Wednesday, January 6, 2010

Running Shoes as Single Factor Thinking

ResearchBlogging.orgThis is a post about Shoes not as evil, but as it seems a Great Feat of Misdirection. It's a wee bit about our biases towards single factor solutions for complex problems, and the arguments we will have around the Chosen Factor rather than pulling up and back to consider the wider view. In science, there's a strong bias towards studying the effect of a single factor in various circumstances, but you'll rarely find a scientist who will say that single factor study or finding is The Solution - as we'll see below. That's down usually to the media who tries to promote such results, or companies that like the sound of same.

We are such complex (and complicated) organisms, yet we yearn for the Single Factor Solution to complex issues. We usually see this with respect to struggles for fat loss, where single approaches - the right diet, the right workout, the right diet pill, the right diet surgery - are put to address what involves a cornucopia of issues, as described here just the other day. The same single factor thinking is evident in running shoes, too. The Shoe is the Solution. Get the Right Shoe before daring a Run. And so this post focuses around a response to a study. About sneakers.

So let's back up: why putitively are there so many durn sneakers out there such that there are studies about their effects? Selling that great shoe that's just right for your running gait peculiarities to reduce injury and let you run like blazes is of course an important thing. And of course the more you can afford the better the protection you can buy. More cushioning, more multiparts of rubber density in the sole etc etc. Or so the sales pitch goes.

But this is also a kind of single factor approach to good mechanics for running. It says let the shoe take care of any weirdness in your gait, cuz that's just the way you are, you're stuck, and so need to be "corrected" . That's a much faster solution (seemingly) than taking the more complex view of IF something is off with the gait that may be problematic for performance, how best deal with that? After all, we're plastic people, as Woolf's Law and Davis's Law have shown: bone and tissue are responsive to what we do. Is this something that can be addressed more holistically perhaps?

And so, as readers of b2d may know, there's a growing movement around "less is more" for foot wear, and indeed "free your feet" anytime of day, and in sports like running as well (with the b2d index of vibram fivefingers stories as a wee illustration) - where the emphasis is on (a) trust our own engineering and (b) work actively with our own engineering to improve it, rather than rely on prosthetics. Prosthetics *may* have knock on consequences, like reinforcing rather than solving an issue.

More Support for Less Support? So it was with happiness that i received the note from Chris from Conditioning research on a Science Daily story: Running Shoes May Cause Damage to Knees, Hips and Ankles, New Study Suggests. Ah good! a study that shoes what we of the Free Your Feet persuasion have been saying for some time. One more piece in the Trust your Foot - it's engineering is older than a shoe company's. There's a study i covered from the summer that showed as well that no matter what shoes for what supposed gait issues a person had, they didn't reduce incidence of injury. That's an important result, since of course these special shoe designs are all supposed to do exactly that: help reduce injuries.

I've written before about why any kind of thick padding and movement restricting of the joints of the food would have a hard time reducing injury when it so limits proprioceptive feedback (our positioning/speed in space), so it's not a surprise that more work is finding specific results showing other issues with running shoes.

Violent Agreement. The following day of the above post, Chris sent me another pointer, this time to Amby Burfoot, a runner's world editor at large commenting on the "dismal science" of the original study. The response is on the Runners blog. And so i was taken aback when the author accused the study's author of being biased because she'd developed a flat shoe.

I'm not calling Kerrigan and Richards liars. Far from it, I agree with Richards's conclusion. But we should understand the motivation behind their writing and their research projects.
This from an editor of runner's world, where the companies best selling issues are their seasonal reviews of new shoes? Likewise, Kerrigan's disclosed company's technology is not what's studied in the reported experiments. It's pretty hard to find a scientist who doesn't formulate a hypothesis or an objective before beginning a study. What was Kerrigan's?
Objective: To determine the effect of modern-day running shoes on lower extremity joint torques during running.
And what were the conclusions?
The findings at the knee suggest relatively greater pressures at anatomical sites that are typically more prone to knee osteoarthritis, the medial and patellofemoral compartments. It is important to note the limitations of these findings and of current 3-dimensional gait analysis in general, that only resultant joint torques were assessed. It is unknown to what extent actual joint contact forces could be affected by compliance that a shoe might provide, a potentially valuable design characteristic that may offset the observed increases in joint torques.
Ok - knees are places that are more prone to a certain type of nasty arthritis. You'd think that more force at the knee would be problematic. We don't know, but we can say that there's more force with running shoes than not, but heck we only have the start of a partial picture here, and something more we'd need to know to enhance footware design we still don't have.

It's pretty hard to get more circumspect about findings that this. Indeed the study concludes with
Although increased repetitive loading has been shown to be a critical factor for the degeneration of articular cartilage at the knee, the forces experienced by distance runners have not been consistently found to increase the risk of onset of knee OA.
But it seems Burfoot is not happy, saying that you can't make connections between forces and injuries. Kerrigan isn't saying that, but Burfoot points to a study where supposedly athletes were asked to jump onto matts they were told were of varying thicknesses, when they were all the same, and the forces measured varied according to one hypothesis goes - expectation - so various degrees of relaxation rather than tensing pre jump had effects on forces. Remember - this is an hypothesis of what's going on. But Burfoot instead says that the same thing is happening in Kerrigan's study BECAUSE the results are the same in terms of more padding; higher forces; less padding more tensed forces. etc.

Right. The same result does not always mean the same process is operating to get that result. And that's just force not torque. But even so, so what? And even more, how possible is it to sustain that tension in a run over time/distance? Burfoot's a runner. How long is it possible to keep up tension when running distances, if that's what's causing less of a strike force or less of a joint torque? It may be possible to psych up and hold forces for one jump at a time, but continuous running?

Is there a Problem Here? Well, the big question is which approach is better for less injuries. Thing is, we don't know. We have lots more data on footwear than on minimal footwear or no footwear. It's a current area of research. AND KERRIGAN'S STUDY ISN'T OVER CLAIMING ANYTHING. It's: here's the data; in the discussion, we THINK this is what it might mean. There are limits to these results, and we may need to check that further.

Burfoot doesn't like that Kerrigan says that the forces at the knee measured in this study of sneakers are higher than those measured comparing highheels to non. He says walking is different than running. True. But the comparisons are RELATIVE. Walking is compared to walking and running to running. And that does indeed as Kerrigan says "represent substantial biomechanical changes" and Kerrigan's paper also states "However, given the substantial increases, there may be other factors as well." How about that. Multifactor thinking.

What Kerrigan's work has done is provide some data to have for later correlations when we start to get bare or near barefoot running population study results.

Anecdotally i know more folks than not who say going to things like vibram fivefingers has improved their experience of stability and confidence and speed and movement and...

Burfoot says he's in favour of as little shoe'ing as possible,
That said, I agree with her apparent position on one important point: Much of what we put under our feet has the potential to do more harm than good. You can't "raise the platform" without increasing instabilities. When you build one of those house-of-cards structures, the higher you go, the closer you get to collapse.

I believe many of us should buy the lowest-tech running shoe we can get away with. For the few who live in Shangri-La, that might mean no shoe at all. For others, it might mean a simple racing flat. For others, the very Brooks Adrenalines that were used in Kerrigan's study.

But some runners shouldn't even look at any shoe other the Brooks Beast, or a similarly built-up shoe. Because, in their experiment of one, that's the only shoe that will work for them
Wow, so all that article comes down to agreement about the main tenants of the "interested party"s findings. Strum and Drang in a teapot?

But all that aside, there's a few more things to think about here in a post finally about single factor thinking. And unlike Kerrigan's speculation about her team's results and their meanings for injury, burfoot has certain certanties, like the last point about "that's the only shoe that will work for them"

Which finally brings me back around to Single Factor Thinking. Here, it's the shoe is the solution. Maybe that's not what Burfoot meant entirely, but when we consider the context of Runner's World again, that's certainly what Runner's World's content is about. The Shoe is the Solution.

Final Fallacy? Let's ask the question WHY would that Beast be "the only shoe that would work for them"? Burfoot doesn't say what "works" means. Is it because their foot position is shite according to some norm, and this shoe is trying to oh i dunno correct stride? to maybe oh reduce injuries? when we KNOW that no specific shoe design does that? It seems that such an assertion is kind of at least partially crap.

Burfoot talks about "an experiment of one" quoting running guru George Sheehan. Well ok, what's the value of an experiment of one? In most cases in science it's zip. zero. nada. And a poorly designed experiment with such a tiny population is even worse. So what IS the experiment of one here supposed to be to determine "works"?

To go try on a bunch of shoes and say "this is the shoe hat 'works' for me" is a pretty crap trial if the Shoe is the Single Factor in the assessment - and if all what one is going for is a comfortable feeling shoe. Unless of course you're not trying on a bunch of shoes, but the sales person has already said "you overpronate; you should only try these" so your selection has just gone down. How many people have said those spring loaded Nikes are the best shoe that works for them? Or what about those totally inflexible Masai's? What are the measures of the experiment there as one's back continues to ache? But they feet feel great so heck you have the right shoes?

That's just poor study design - if you're interested in the performance of an entire system, not just the foot.

If the Shoe Fits as More Single Factor Thinking Kerrigan's group's study's conclusions aren't my happy place either, personally, but close. Their take away is that shoe design has focused on the foot's mechanics to the exclusion of the rest of the gait - or at least the knee. One joint further up the chain. Her work is saying that for good or ill those designs are having knock on effects up the chain. And for her, designing a shoe that minimizes those effects seems like a good idea.
The development of new footwear designs that encourage or mimic the natural compliance that normal foot function provides while minimizing knee and hip joint torques is warranted. Reducing joint torques with footwear completely to that of barefoot running, while providing meaningful footwear functions, especially compliance, should be the goal of new footwear designs.
Gosh, that sounds like vibram fivefingers - for example - to me. Just get out of the way of the foot. But then we have tricky words like "compliance " as "meaningful footware functions." Hmm. One can now go to kerrigan's company's page for what she thinks is a good compromise answer for the problem that, "The use of athletic footwear in running as a means to protect the foot from acute injury and the potentially debilitating effect of switching to barefoot running on foot health excludes such an alternative"

Ok, what potentially debilitating effect of switching to barefoot running? The "potentially debilitating effect of switching to barefoot running" sounds so much like the same old rationales for selling cushy sneakers in the first place. Be afraid. Be very afraid of putting your foot down in a running gait without some kind of Protection.

Getting Shod of Being Shod Here's an idea: start with your bare feet. Are you happy walking around in your bare feet? Neutral? Great. Why not move more that way? Why not find shoes that will enable that to happen? Some folks even recommend progressions - from whatever one is in now, to Nike Frees, and from there to thin soled shoes like running flats, and then to Vibram FiveFingers, and THEN - gosh, ya just gotta try au naturale as PART of a program of enhanced mobility?

In my experience working with athletes who have running issues, the ONLY time i've seen going to a no shoe (what Burfoot prefers) is when they've had some particular issue with a bone or otherwise that requires more often than not some cushioning and some support TEMPORARILY as they work out of PAIN AND work on other parts of their movement.

The Non Single Factor. In one case, this working towards let's call it raw or natural movement involved strategies to address inflamation (some diet changes in that case), some movement work, AND some foot orthotics and very neutral shoes with cushioning as said to help move the person out of pain.

In other cases, dealing with achiles issues, i've seen folks slowly, progressively moving into shoes that pass the twist test (bend from one end to the other, not just at the ball; twist like ringing out a tea towel) as PART of their rehab experience accelerated recovery.

And more, folks who have switched to twist test passing footwear as PART of a program to better global movement also seem to report other aches etc going.

So i'm not going to claim that better quality of physical life is all down to twist passing footwear - that would be single factor - but why that footwear seems to help is that it lets us find a truth about our movement, work with that movement, improve that movement, and not have a device like a shoe type mess up that work. In fact by using the most flexible footware possible for the person, it seems, we get a whole lot more reps for our bodies to practice that movement.

I say this typing having hoofed it up to work in a pair of vivo boots (snowing outside) and having changed into a pair of VFF's for the office. So it is possible to respect our feet even in winter weather. Snow shoe boots with rubber grips are also awesome possibilities.

So my combo? As i've suggested many times now:
  1. - get a movement assessment to check out your WHOLE way of moving so you're not, as gray cook says, putting strength on top of dysfunction. Such an assessment will give you some strategies/movements to practice to optimize your athletic movement. Here's a list of z-health movement coaches (i do video consults too via skype - email me, link end of post)
  2. - take up a mobility practice to support and enhance full joint well being for better movemen and injury prevention. Some folks like t'ai Chi and related. Sure. i like z-health. Here's why in comparison with those other approaches.
  3. - move towards footwear that increasingly passes the twist test (gets closer to letting our feet be our feet without interuption). CAVEAT If anything causes pain/discomfort, stop, go back a step, slow down. Check with your movement specialist. Pain is a signal to change. So worth attending.
In other words, put the foot, and the shoes we wear on 'em into perspective. Running is NOT about the shoe. It's about our whole bodies moving. Are they moving well in that practice? What's the best way to support the optimal movement of the whole system?

The above list does not take into account all of the other factors that can play havoc with movement quality/injury suseptibility like nutrition, rest, stress, recovery etc. All of these things need to be considered as well as part of the whole system. My wee combo set is that a more rich place to begin thinking about running, is to think about running, the whole movement - and moving well - and looking at how to enhance that for ourselves rather than hitting a crutch first - especially one that has been shown to have no effect on the very thing it's been claimed to do: reduce injuries.

Kerrigan, D., Franz, J., Keenan, G., Dicharry, J., Della Croce, U., & Wilder, R. (2009). The Effect of Running Shoes on Lower Extremity Joint Torques PM&R, 1 (12), 1058-1063 DOI: 10.1016/j.pmrj.2009.09.011

Knapik JJ, Swedler DI, Grier TL, Hauret KG, Bullock SH, Williams KW, Darakjy SS, Lester ME, Tobler SK, & Jones BH (2009). Injury reduction effectiveness of selecting running shoes based on plantar shape. Journal of strength and conditioning research / National Strength & Conditioning Association, 23 (3), 685-97 PMID: 19387413


Boris T said...

Great post, also great blog.

I am fan of minimalist and barefoot running and you've point to many reasons why everyone should consider it. There the notion of "correcting" a problem without actually addressing the cause of it but rather patching over the symptoms.

Anonymous said...

I very thought provoking and reasoned post! I'm a barefoot/VFF runner and blogger in NYC. I'm going to grab your RSS feed!

Take care.

Helix Matrix Healing said...

Well I have one thing to say armed forces run in boots as well as trainers and most have big knee problems.. I had some issues too with knees and the way I walked from it so I say less is most definately more and working on posture alignment to the way you walk also helps.. which I found out from pilates studio teacher but before I found the VFF's I got myself the MBT's which helped alot with walking and running the correct motion of the foot so I now go between barefoot around house to vff to mbt sandals or boots depending on what doing....

dr. m.c. said...

Thanks all for stopping by. Much obliged. Happy trails to you in 2010 and beyond.


Richard Chignell said...

Yo MC!

You know i am running minimalist. Dependent on weather it's either something like vivos or fivefingers or nothing.

I used to suffer from knee injuries, was prescribed orthotics, and, stability shoes etc. Since making the change away from cushioned shoes i have never ran better and never had even a twinge in my knees.

The only thing i would emphasise (which i know you cover) is that the change should be made gradually. Repeat SLOWLY people. Your calf muscles and achilles will thank you. If you do move into it slowly the gains are fantastic.

My only bug is that for trail runners footwear with enough grip is problematic and fivefinger treks leave the toes awfully exposed to the rocks you inevitably kick during night runs.

Great post - i will repost to my blog and perhaps some ultra runners will pop by and discover Z.


Harry Munro said...

Great article. I switched to VFFs after getting bad shin splints. A year later I can run any distance with no pain whatsoever.
Let us not forget that runners world is in the business of advertising trainers. Barefoot is not a very lucrative market!


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