Study: Running Economy Improves After a 4 Week Simulated Barefoot Running Program

English: Vibram FiveFingers Bikila shoes, top ...

English: Vibram FiveFingers Bikila shoes, top view. (Photo credit: Wikipedia)

The question of how footwear (or lack thereof) affects running economy has received a great deal of attention over the past year or so. Several studies have come out that have compared oxygen consumption in runners in both shod and unshod states, and most recently Franz et al. published a study showing that among habitual barefoot runners there is no significant difference in economy when “barefoot” (wearing only socks) vs. running in a lightweight racing flat (see my commentary on the Franz study here). The Franz study concluded that any economy gains due to weight savings when running in a simulated barefoot condition seem to be balanced by economy losses due to the lack of cushioning, which results in a non-significant difference between the “barefoot” and shod conditions.

However, until now, studies have not looked at how economy changes as a result of a period of barefoot or minimally shod training. A study, titled “Four-week habituation to simulated barefoot running improves running economy when compared with shod running,” was just published on-line in the Scandinavian Journal of Medicine & Science in Sports. In the study, authors J.P. Warne and G.D. Warrington of Dublin City University in Ireland investigate how 4 weeks of training in Vibram Fivefingers affects running economy and a variety of other physiological and biomechanical variables.

Methods

The study authors recruited 15 experienced collegiate runners who each ran a minimum of 6-7 days per week (minimum 50km per week of training). None of the runners were experienced or habitual barefoot runners. Each runner was given a pair of Vibram Fivefingers (VFF; weight = ~150g) and a neutral training shoe (weight = ~450g). During the pre-test, running economy was determined for each footwear condition by measuring oxygen consumption while running at both 11km/h and 13km/h on a treadmill. The researchers also measured heart rate, rated perceived exertion (RPE), stride rate, and foot strike type.

After the pre-test, the runners were assigned a 4-week transition program to acclimate them to running in the Vibram Fivefingers (the simulated barefoot condition). They maintained their typical weekly training volume in their typical shoes, but gradually added (or substituted) in mileage each week in the VFFs (two 15 minute runs the first week, up to 3-4×30 minute runs in week four). At the end of the four week period they ran a post test that was identical to the pre-test conducted at the outset.

Results

Pre-test results showed no difference in running economy between the training shoes and VFFs at either speed. Previous research has typically found that a 100g reduction in shoe weight leads to about a 1% increase in running economy. Given that the VFFs weighed ~250g less than the training shoes, it appears once again that any economy benefit of the reduced shoe weight seemed to be balanced by losses resulting from other properties of the barefoot-simulating footwear. These losses could be due to a lack of cushion, or in this study possibly a lack of familiarity with how to run efficiently in a barefoot-simulating shoe at the outset. The only difference that was found between the footwear conditions for the pre-test was that runners had a higher stride rate (and thus a shorter stride length) in the VFFs (83.69 strides/min in VFFs vs. 81.54 strides/min in training shoes).

What happened next was interesting. After the 4-week acclimation period, running economy in the Vibram Fivefingers increased dramatically (~8%), RPE decreased by 9.45%, and foot strike shifted more toward the forefoot. To a certain extent this is to be expected – as they acclimated to the novel footwear condition, the runners got more comfortable and more efficient at running in the barefoot-style shoes. However, more surprising is that in the post-test comparison the runners were now about 7% more economical in the VFFs than they were in the training shoes (the difference was statistically significant). They also tended to land more often on the forefoot in VFFs, and continued to run with a higher stride frequency in the VFFs compared to the training shoes. Economy in the training shoes improved by 2.32% after the 4-week period, but the improvement was not significant and the authors point out that this could simply be a normal training effect (i.e., 4 weeks of additional training would be expected to have some physiological benefit).

Commentary

So the big question here is why the runners were so much more economical in the Vibram Fivefingers when compared to the cushioned training shoes after using them for 4 weeks in training? The magnitude of the difference exceeds what would be expected from the weight difference alone (even when combined with any physiological benefit from 4 additional weeks of training), and the authors discuss some possible explanations. They speculate that the combination of increased stride frequency and landing more toward the forefoot may have resulted in a more effective recovery of elastic energy in the muscles and tendons of the feet and legs. They suggest that increased feedback from the ground surface when wearing a barefoot-simulating shoe might, through a period of motor learning, lead to “increased coordination and pre-activation of the dominant running muscles in anticipation of ground contact.” The resulting form changes (e.g., increased stride frequency, limb stiffness adaptation through changes in joint angles, and foot strike modification) could then explain the benefits to running economy in the barefoot-style shoes.

As I read this study I kept wondering to myself why they found such a large difference in economy between the VFF and training shoe conditions when Franz et al. found no significant difference in economy between “barefoot” (socks) running and running in a light racing flat (Nike Mayfly). There are a couple of differences between the two studies that are worth considering. First, Franz et al. recruited experienced barefoot runners and screened their subjects to only include those who landed midfoot/forefoot. They were specifically interested in the effects of shoe weight, so they tried very hard to control for form/biomechanics. In the Warne and Warrington study subjects were not experienced at barefoot running, and biomechanical differences were observed when they ran in the VFFs vs. training shoes both before and after the 4-week habituation. As such, form changes (e.g., shorter stride, foot strike change) resulting from a period of simulated barefoot training could explain at least part of the improvement in economy in the VFFs, and these may not have yet translated across to the training shoes (more time needed perhaps, or just not likely to happen in a 12oz training shoe?).

Another thing to consider is the type of footwear used for the “shod” condition in the two studies. Franz et al. used a light racing flat (Nike Mayfly), whereas Warne and Warrington used a heavy trainer (400g). It’s possible that some property of the shoes used influenced the results – for example, there may be a point of diminishing returns when it comes to shoe cushioning. As is pointed out in this article in the NY Times (discussing another study from Rodger Kram’s research group), there may be a cost to too much cushioning. As a personal aside, I find it very, very hard to run the same way in Vibram Fivefingers and a 12mm drop, 10oz+ training shoe, and I don’t know that form changes will ever perfectly translate from one to the other due to structural differences between the shoes (I don’t know if it’s wise to even try forefoot striking in a 12mm drop shoe).

One other related study is worth mentioning. In 2009, Squadrone and Gallozzi published results on habitual barefoot runners in which they found them to be about ~3% more economical in VFFs compared to traditional training shoes, which could be explained in part by a weight effect (though economy when barefoot was the same as in VFFs). However, even among these habitual barefooters there were biomechanical differences between the shoe conditions (e.g., joint angles at contact differed, foot strike was more posterior, contact time was higher, and peak impact force was higher in the traditional shoes vs. VFFs). All of this points to the complex effects that footwear can have on running gait. Shoe properties matter, experience of subjects matters, as do probably a variety of other factors.

Will this study end the debate about whether barefoot running is better or worse, or just different? No, not likely. But, it does provide some additional evidence that including some amount of barefoot or minimally shod running in your training routine can help you develop a more efficient running form (and things like barefoot strides have long been used as a training tool by high level runners for this very reason). However, it’s worth noting that benefits accrued from “barefoot” training may not translate directly to running in a traditional training shoe, particularly if your form reverts when running in that shoe. What needs to be done now is to figure out which factors specifically explain benefits gained as a result of barefoot/minimal training, and figure out how best to get those to translate to running in other shoes.  A longer term study might help accomplish this, and a study incorporating more explicit form training and cueing might help as well.

I always like to end posts like this with a call for anecdotal experiences – some hate anecdotes, but I find them interesting and informative. Have you sensed an improvement in your economy or perceived exertion after migrating to a more minimal or barefoot-style shoe? Share your thoughts in the comments!

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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. Eric Narcisi says:

    I also used Mizuno Ronins as a transition shoe, sort of. I used to train in bulkier shoes like the Mizuno Inspire and was a heel striker. It was weird since it quite often felt clumsy. I noticed that in races where I was wearing racing flats I’d have more of a mid- to forefoot strike, then my calves would be screaming at me after. How much sense did it make to train one way and race another? I always seemed to be dealing with injuries too. I went out and got myself a pair of VFF’s but realized I wasn’t ready to run in them right away. What I did to build up to that was slowly work in less shoe. I started mixing in more runs in the Elixirs, then pretty soon all of my runs were in Elixirs. From there I worked in runs with the Ronins, and then pretty much all of my running was with the Ronins, and throughout the whole process I made sure to focus on the forefoot landing. After a couple of months of this, the results were quite astounding. Every run felt amazing, and at the age of 31 (back in 2011), I PR’d in just about every distance. My road 5k PR even surpassed my old college PR which was run on the track. My quads, which were always knotted and beat, were pretty smooth and stronger than ever. I never did get to run in the VFF’s that much, as I ultimately decided that it was too little cushioning for me since most of my runs were on the hard city streets. I did work them in now and then to improve my foot strength and form. I should also note here that I did develop some painful post tib tendonitis, which makes me think that either I still moved too quickly to essentially training in racing flats, or I just needed to strengthen the feet and calves more. I also ended up tearing a hip labrum, but again I don’t necessarily think that was all because of this. I had been feeling pain in the area off and on for years and kept working through it. I think attempting a marathon while fighting through the tendonitis (goal race for the training cycle) caused it all to blow up. After surgery, I’m headed towards a full recovery and plan on going the minimalist route again once I start running.

  2. Blaise Dubois says:

    So, again evidence going in the same direction : When considering performance, the most efficient running shoe is the LIGHTEST and the one providing MINIMAL PROTECTION from an environment to which the foot is not adapted. My opinion : All runners who want to improve their performance should transfer smoothly to use more and more lighter minimalist shoes, to train and to perform… and if their body tolerate the load, why not 100% of the time after one year?

  3. Rodney Bowman says:

    I started 2 years ago wearing the Guide 4. After 2 pairs, I transitioned to the Mirage and I immediately noticed a big difference in my running economy. That shoe started me down the path of lower drop and lighter weight shoes. I eventually even started running completely barefoot. I believe that each runner adapts differently and can see advantages or disadvantages to more of a barefoot, transitional, or minimalist shoe. It helped me to change my stride and improve my endurance. I run with hard-core only barefoot, minimalist, and traditional runners. The thing I have noticed is cadence and maintained speed during a run as being things that separate my experiences running with each. I have absolutely shortened my stride and recognize more quickly when I feel something that isn’t quite right when running. One other minor thing is that my feet have widened slightly. I don’t require a wide shoe, but I notice some styles are snug now. Overall my transition has been a great learning experience. I now spy out new shoes like a car enthusiast looks for the latest supercar.

  4. Ten years ago for a job test I was barely able to finish a 3-mile run just under 27min, the cutoff. That was me giving everything I had and running faster than I ever did and ever have since then until this year. I used to be a severe heel striker and my shins and knees wanted to explode by half a mile. Even moreso, my lungs would just beg for mercy if I forced myself to endure the acute pain in my legs. I never ran more than a mile at a time since then. This was kind of weird because I’ve actually always been a pretty athletic guy and competed in lots of contact and combat sports. I was also always very good at sprinting.

    This past March I discovered a minimalist shoe at the store which led led me to read up on the concepts surrounding running gait. I ordered a pair of Mizuno Ronin 2s after reading your review and the suggestion of using it as a transitional shoe. My previous shoes for the past 4 years were Saucony Omnis. WITH a cushioning insole ON TOP of the sockliner. I thought I needed as much cushion as possible to alleviate that incredible pain in my knees and shins. Looking back I’m certain it encouraged me to heel strike like crazy. For my first run ever in months I just tried not to take giant steps, instead almost shuffling my feet along, floating just above the ground. I ran 1.5miles nonstop that day in the Ronins before my lungs finally felt uncomfortable (my knees and shins were fine). It was quite a feeling finally breaking the 1 mile barrier without wanting to throw up. Since then I’ve kept below 9mm in heel drop and I have zero doubts I have transitioned to a midfoot strike (I’ve used video and kept track of my sole wear).

    I regularly compete in 5Ks now and quickly became a consistent top 80-90% percentile placer in most every race. I’ve survived a 10-mile trail run and am now training for a half-marathon. I very much credit the change in gait for the majority of this.

  5. I’m sorry I can’t read the full article. I’ve got a few questions:

    1. The 400 gram training shoe- was it the same model used by all of the runners?
    2. All of the runners trained 4 weeks exclusively in the VFFs?
    3. All of the pre and post testing was done on a treadmill?

    • Pete Larson says:

      Sometimes can be hard to tell form the article, but yes, I think the same shoe used by all runners, though 400g is an average as it would vary by shoe size. Training was not exclusively in VFFs – I mention in the methods how they did it, but they maintained normal mileage in shoes and gradually introduced the VFFs in a graded fashion. Yes, pre and post testing on Woodway treadmill.

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      • OK, got a better picture of what they did.

        My comments would be that a more ideal study would be to have some of the runners continue training in their personal training shoes. And have some of the runners gradually work into the 400g “study” shoes from their regular training shoes. This would give a couple of control groups for comparison. Wishful thinking of course! Recruiting a large body of subjects for these studies couldn’t be easy, especially when you need a uniform group of runners with VO2 max numbers in the 70s! It seems like a study that says “interesting result, do some more studies”.

        • Pete Larson says:

          Exactly, lack of control groups was to me the main thing lacking, but my guess was also that it was due to sample recruitment difficulties

        • As a crude estimate of the talent of the runners in the study, I looked up the estimated 5 km race time for a VO2max =70. 15 minutes 18 seconds! This is from the “Pace Effort Tables” in the RRCA Coaching Certification book. Not your typical recreational runners for sure!

  6. John Williams-Searle says:

    I’m a big fan of Dr. George Sheehan’s admonition that we are “an-experiment-of-one” when it comes to running, which also suggests the importance of anecdotal experience. I have been going minimal since the fall of
    2009, when I shifted to a pair of Nike Free 3.0s to combat a bad case of plantar fasciitis. I alternated the Frees with a pair of Lunaracers, successfully eliminated the plantar fasciitis, and became a forefoot and midfoot striker who
    now finds it just about impossible to heel strike. In retrospect, I transitioned to a new running form and footwear far too quickly and managed to give myself a right tibia stress fracture. After I recovered, I continued to improve my form by increasing my stride rate and decreasing my stride length. I now train in Zoom
    Streak XC 3s and Lunaracers. My own experience has convinced me that one of the big keys to decreasing injury and increasing racing speed are form adjustments – particularly the elimination of over striding – that can be encouraged through minimal footwear. I think that my biggest problem was over striding (and running my easy runs too quickly) and that minimal shoes help to enforce good form because you just can’t keep heel striking – too painfully jarring.

  7. yep, can’t stand even a transition shoe like the kinvaras

    gone barefoot, will stay that way, trying to find the best minimal shoe that can do it all

    since going minimal 2 and a half years ago, running became comfortable again, hadn’t experience that since i was barefoot before i was in kindergarten, well, and the time i wasn’t in school

    i’m a much faster distance runner than i was and my form is awesome, i’ve been making sure of that

    makes sense, cool study

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  1. […] Some studies have even begun to determine that you can be more efficient in a minimal shoe; Runblogger has a great rundown fo the report and explanation of what it means for a regular […]

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