Strengthen Your Feet with Less Shoe?

If you missed the barefoot/minimalist presentation at The Running Store last Thursday, the remainder of your life will have a significant void in it 🙂    Thanks to The Running Store for the opportunity to talk.

I am of the opinion that doing some barefoot running every week will gradually change many faulty mechanics and, as that changes, you can transition into less bulky of a shoe.  The “barefoot” part for most runners however, I feel is merely a tool – not a complete mutiny against shoes .  Just like doing speed work/intervals or “A” skips and “B” skips and butt kicks, barefoot running can be done briefly a few times per week.  This is certainly not a new concept.  For decades, coaches have told their runners to do some barefoot running.

The presentation at the Running Store mostly consisted of what changes occur in stride mechanics when you take your shoes off and what the advantages of going to a more minimalist shoe would be.   One thing we never covered in the presentation is what I want to talk about today – the issue of “foot strengthening” via wearing shoes with little to no support.

6 pack foot

(Yes, that picture was photo shopped, no you can’t do foot sit-ups to get a six-pack in your foot)

When the Nike Free emerged, the big selling point that Nike had was the idea that modern footwear has weakened the muscles of our feet and lower legs.  As an analogy, you would get very weak neck muscles if you wore a cervical brace for your whole life, yet, they asserted, this is what shoes were doing to our feet.   By wearing the incredibly flexible Nike Free, they told us that we could strengthen the muscles and by association, reduce injury.  They wanted the public to “Train Your Feet” as seen in this brochure. The implication was, that weak feet lead to an unstable base of support for your legs and thus, more potential for injury.

So what of it then?  Can we really strengthen our foot muscles by wearing less shoe?  Unfortunately, we have very little evidence to go on here.  I can find tons of anecdotal stuff out there, but only 3 studies.  One is in a peer reviewed journal, the other two are studies presented at scientific meetings, but not published in peer reviewed journals.  Below, I have written a summary of each study and put a link to the study.  If you want to read them…have at it!  For those of you who don’t care and just want my opinion, just keep reading normally.

Two of the studies measured the “pre-study” foot strength and took MRI’s to measure the girth of the foot muscles.  Then, they had half the group train in Nike Free’s and a control group train in conventional shoes.  By “training” they meant skipping, running, aerobics etc.

In the end (about 6 months), the Nike Free group had increased strength in the foot muscles and increased size of the muscles in the feet.  In other words, wearing a less stiff and bulky shoes, the subjects did, in fact strengthen their foot muscles.  Based on these two studies (one funded by Nike) we can begin to form the idea that wearing miminalist shoes or going barefoot can strengthen the foot muscles.   Does this create a more stable base of support for the legs and in turn, reduce the potential for injury?  We simply don’t know.  It certainly sounds like a reasonable thought!  In the next few weeks, I hope to get a newsletter out showing a progression of foot strengthening exercises.

For those who are detail oriented, read on…

Study #1.  Found here

Studied 100 runners and took strength measurements of the feet and toes and MRI’s of their feet and lower legs (to measure the girth of the foot and lower leg muscles).  They were divided into two groups and that all had to do weekly exercises including running, skipping and aerobics for 6 months.  The difference was that one group was wearing conventional running shoes while the other group wore Nike Free’s.  The results?  The Nike Free group ended up with significant increase in the toe flexion strength and on the MRI’s, the flexor hallucis longus (the muscle that pushes the big toe down) was significantly larger after the experiment.  Some other muscles trended toward an increased girth, but the difference was not statistically significant.

Study #2.  Found here

This study looked at 50 individuals and the study was very similar to Study #1.  They took strength measurements and muscle belly girth measurments via MRi and then split the group in two – one group wearing Nike Free’s and the other group conventional running shoes.   This study was 5 months long but again, showed statistically significant changes in muscle strength and girth compared to the group wearing conventional shoes.

Study #3:  Full text of the study found here.

Basically, this study analyzed the foot arches of 1846 individuals in India who were skeletally mature (aka “adults”, but I’ve met many skeletally mature people who I hesitate to call “adults”).  In a nutshell, the researchers found that kids who were barefoot for the first 6 years of their life (the more formative years, I guess).  Of the kids that wore shoes regularly,  8.2% had flat feet, while 2.8% of barefoot kids had flat feet.   No other factors had any influence on the shape of their arches.

What does this third study tell us?   Not much, as far as I’m concerned.  First of all, it’s an observational study – not exactly strong.  Secondly, did the flat feet correlate to injury of foot problems later in life?  We don’t know – although that seems to be one of those urban legends.  Thirdly, this study assumes that measuring the height of the arch in a static position somehow correlates to the way the foot moves when walking or running.  I know of at least 6 well controlled studies that say static arch height doesn’t have any influence on the moving foot dynamics.