INTRODUCTION 

I recently had the pleasure of attending a 2 day course titled “evaluation and treatment of the injured runner” with Dr. Irene Davis and Dr. Richard Willy, arguably two of the world’s leading running researchers.  You may have heard of Dr. Davis as she is often touted as the ‘barefoot running expert’ and appears in Chris McDougall’s iconic book Born to Run.  More appropriately she should be known for being a prominent researcher of such calibre that Harvard Medical School recently created The Spaulding National Running Centre to allow her to further investigate running biomechanics.  The following is a summary of some key research supported findings presented over the weekend.  The take home point…..we really don’t know too much of anything yet!

PREAMBLE

To begin, there are a number of different foot striking patterns.  This video is a cool slow motion clip taken from one of the lead packs at the 2010 Boston marathon.  Check out the variety of different foot strike patterns in this ridiculously fast group.  Some are forefoot strikers, some are rear foot strikers, and some are in between.
Now check out this video of the same race (slower runners this time…..the first group was running sub 5 minute miles!) with a barefoot runner mixed in.  A VERY small sample, but notice how the runners wearing shoes (shod runners) tend to heel strike, while the runner that is barefoot lands more on the ball of his foot.

Over 80% of current runners are rear foot strikers, while just 1-2% are forefoot strikers.  Which strike patterns is the best?  That’s what we are trying to establish…….

RUNNING AND INJURIES

In any given year nearly 80% of runners will sustain an injury, 46% of which will be injury recurrences.  With such a significant number of injured runners and with so many people now running, there is a lot of funding to find out how and why runners get injured.  The first reasonable explanation is on how we are put together (our structure).  Yet there are a number of studies that show no correlation between body structure and running mechanics.  Nor are there studies correlating body structure and injury.  Dr. Davis has an interesting take on these studies where she expressed skepticism as she noted that these studies are taking individuals from a normal population.  This means that for the most part they are within the normal range for structure and have no injuries (typically normal is defined as the mean plus or minus 2 standard deviations for those wondering).  She hypothesizes that if you take a group of individuals outside of ‘normal’ body structure and measured their gait patterns you would see injuries.  Because of this she has reservations about concluding that structure has no impact.  Pretty cool and open minded researcher.

HER TAKE ON BAREFOOT RUNNING

Dr Davis has no financial relationship or commercial interests tied to barefoot running.  Instead, hers was a personal journey that included a 30 year absence from running following persistent injuries as a physiotherapy student.  Later, in her fifties, she has again began running however this time entirely barefoot (that’s right…..no socks, nothing!) and has so far been injury free.  When questioned she flat out said “Ya last night I did 30 minutes down Leslie Street and back completely barefoot”.

Why barefoot? Her take is that we as humans have been de-evolving ourselves with the modern shoe.  We were made to run barefoot and have done so for millions of years.  Even previous running shoes up until the 1970s were minimalist, defined as providing no support (no arch support, no heel support) and no cushioning (ie no midsole).  Minimalist shoes simply provide protection for the bottom of the foot.  In 1963 while Phil Knight was still working at Asics, they imported the Onitsuku Tiger shoe to the US, the first shoe with a large cushioned heel.  In 1972 he jumped ship and formed Nike producing the Nike Cortez which brought the ‘contemporary’ shoe to the mainstream.  Now, 40 years later, the ‘modern running shoe’ has an elevated cushioned heel, stiff heel counter, large arch support and a very dense midsole.  Another way to think of this is a cast for your foot!  Dr Davis even showed the Asics Gel-Kayano 16 which was purported to “Adjust stiffness according to your time of the month” for hormonal changes!  Awesome!

We have previously covered the research findings on the potential benefits of running minimalist or completely barefoot.  But do shoes help at all?  When you enter The Running Room now a sales rep will ‘fit’ your foot type to a cushioned sole, or stability shoe.  Contrary to popular belief this is entirely unsupported in the literature.  In fact, a study took a large sample of army recruits and matched half according to their foot type and gave the entire other half stability shoes and surprisingly there were less injuries in the stability only group!  The conclusion? “Assigning shoes based on the shape of the plantar foot surface had no influence on injuries.”  In fact, there has never been a single piece of evidence that footwear in any way reduces injury!

Other issues with modern shoes include promoting rear foot striking (which has a higher impact transient force – bad), they also increase stride length (it has been shown that injury risk is reduced when taking shorter strides despite the fact that you are taking more steps). Additionally the fact that they are soft makes you land harder (you actually land harder when you land on soft surfaces) and they also PROMOTE pronation or flat footedness at midstance – think of rolling your foot in – due to a longer lever arm.

The piece of research that was the ‘ah-ha’ moment for Dr Davis?  A study found that simply adding even thin socks to bare feet significantly decreases postural stability compared to bare feet.  But shoes must make us more stable at least?  In truth, a recent study showed that shoes promote greater dynamic INSTABILITY with single leg landing.

Overall we have trained our feet to be lazy!  We have been putting our feet in casts at a very early age and then using these casts the rest of our lives.  This significantly decreases the strength in our feet.  When we put our feet in minimalist footwear there is improved strength, balance and agility over time as seen in a study done on the popular Nike Free 3.0’s.

So is barefoot the be all and end all?  Not necessarily.  For forefoot strikers, it’s not all pleasant.  There are more injuries in the triceps surae (Achilles and calf).  Also, at midstance (when your foot is flat on the ground), ankle dorsiflexion (ankle flexion) is still the same for forefoot strikers as rearfoot strikers.  This means that there is more total excursion (total motion) through the ankle during gait over the same amount of time.  Also, there is greater demand on the ankle plantar flexors (your calf and achilles).  This results (in general) in more ankle injuries in forefoot strikers.  Conversely for rear foot strikers, your knee flexes more because the ankle is more rigid.  This results in more knee injuries in general.  Which is better?  I don’t have any idea…….

HOW TO TRANSITION TO BAREFOOT RUNNING

Transitioning from something you have done your entire life (wearing shoes) to something entirely new (barefoot) is difficult.  There is no literature on the best approach to transition out of shoes however here is what Dr. Davis suggests:

• To get out of orthotics, go opposite from how you got IN them (for example 1 hour the first day, 2 the next, 4 the day after that etcetc).
• Second, begin walking barefoot or in minimal footwear (up to 30 minutes briskly).  This will increase your proprioception and sensory input and increase your foot strength.  You will likely have heel pain during this phase, and hence the slow work up.
• Finally start running: Dr Davis prefers a ‘cold turkey’ approach with progression: ie run 9 minutes, walk 1 and increase this as required.
• During this entire time, you should be performing foot strengthening and arch height exercises to build intrinsic foot musculature – ask a qualified therapist like those at The Proactive Athlete for help in this regard. 
• For a barefoot transition program Dr. Davis promotes a program that was originally designed to re-integrate people to running following stress fractures.
• Pain: It is a GIFT to humans to say ‘stop’.  It is mindblowing that we push ourselves through a built in ‘intrinsic stop mechanism’.   

OTHER COOL ITEMS FROM THE COURSE THAT ARE OF INTEREST

Gait retraining is a key, not just for injury prevention, but in the treatment of current injuries.  Although most therapists prescribe exercises in an attempt to change a patients gait pattern (and I am guilty of this also), Dr Davis recently showed that exercises alone DO NOT ALTER GAIT MECHANICS.  All they do is strengthen the muscles you prescribed exercises for.  You need to include gait retraining to affect gait.  Although there are extremely expensive marker based systems to give runners input on their gait patterns, it has been shown that utilizing nothing more than a treadmill, a mirror, and a qualified therapist will have the same impact as high tech equipment.  In fact, treadmills are more useful than you would suppose.  Although research shows that while on a treadmill you run with a slightly shorter slide, and you land slightly more flat footed (less dorsiflexion), otherwise there are very few differences….in fact it is almost exactly the same.  Vertical ground reaction forces are the same, as are AP forces (your braking force).  Therefore it is an extremely useful tool for gait evaluation.  

People get fixated on arch height.  In truth, arch heights DO influence lower extremity mechanics and therefore injury risk:  Runners with high arch heights have a higher vertical load rate meaning they land harder (think of a ‘plodding’ runner with a stiff gait).  These folks trend to lateral (outside) foot injuries and bony injuries while low arch heights trend to medial (inside) foot injuries and soft tissue injuries.  Interestingly, plantar fascia pathology is seen in both arch heights.  The thought process being that high arches place the fascia in a constant state of tension while low heights cause a bottoming out effect, again stretching the fascia.  Both states cause a repetitive strain on the fascia…..so really either way you are screwed.

CONCLUSION

There really is no conclusion……yet.  The barefoot running literature is now fairly robust (at least more so then what we typically rely upon as manual therapists).  It is a fertile ground for even more research and the landscape is broad.  Dr. Davis hinted at a few pieces that are underway at Harvard including a large prospective trial on barefoot running versus shod (wearing shoes) running on injuries.  I also came across this Canadian study that is ongoing (funded by Nike) chaired by Dr. Jack Taunton, a Sports Medicine Physician who was the past Chief Medical Officer of the Vancouver Olympics.  So where do we go from here?  I’m going to buy a pair of minimalist shoes and attempt to transition into them over the next few months……keep tuned for how that goes.