The Science Behind Barefoot Running. Is it the right thing for you?

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In this article I will briefly discuss the different styles of running and how they relate to running performance. The majority of the article will relate to the explosion in popularity of barefoot running, discuss the positives and potential negatives of attempting to run barefoot (or in barefoot style shoes). I will then wrap up with discussing the Vibram Five Finger shoes, which are a popular barefoot style shoe, and how to incorporate running in them. While there is a plethora of technical information contained in this article, I invite you to look at the summaries and conclusions of the article, which contains the information that is important to you, the runner.

There are three types of runners: rear-foot strike (RFS), mid-foot strike (MFS), and fore-foot strike (FFS). It has been shown that the fastest endurance runners tend to be FFS runners (2). The reason for the different types of running styles is not clear, but a recent article published in Nature, (3) one of the top ranked peer-reviewed journals in the world, may shed light on the differences and may support the idea of barefoot running. In this study the authors looked at foot strike kinematics in five groups of runners while they ran on a track at their preferred endurance speed. The groups consisted of 1) runners from the USA that wear shoes 2) Kenyan athletes that grew up running barefoot but now wear shoes 3) runners from the USA who grew up wearing shoes, but now run barefoot or with minimal footwear 4) Kenyan adolescents that have never worn shoes and 5) Kenyan adolescents that have worn shoes for most of their lives. Lieberman, et al found that runners who wear shoes and who grew up wearing shoes have a RFS when wearing shoes and also barefoot, though they tend to have a flatter foot placement while running barefoot. Runners who either grew up barefoot or switched to the barefoot style of running were predominately FFS runners. The authors state that while high-heeled running shoes are more comfortable, they do limit proprioception and make it easier to heel strike. Furthermore, many running shoes have high arch supports and stiffened soles. This may weaken foot muscles and reduce arch strength, which then leads to excessive pronation, greater demand on the plantar fascia, and lead to plantar fasciitis.

While running, at foot strike, there are ground reaction forces that occur. In RFS runners this collision force can be 1.5-3 times the body weight of the runner (3). The impact transients travel rapidly up the body and may contribute to injuries such as tibial stress fractures (4) and plantar fasciitis (5).

Lieberman, et al (3) found that at similar speeds, the peak vertical force that occurs during the impact period of the run stride are approximately three times lower in habitual barefoot runners who FFS compared to runners who habitually wear shoes and RFS while barefoot or in shoes. On average, the impact force in RFS runners either barefoot or with shoes is roughly 1.75 to 2 times body weight compared to FFS runners who are barefoot who experience impact forces approximately .5 times their body weight.

With the increased interest in barefoot running, shoe manufacturers have developed products to mimic barefoot running while protecting the athletes from stones, pieces of nails, glass, etc. One such shoe is the Vibram Five Finger Shoe. Recently, a study compared the running gait in experienced barefoot runners while they ran barefoot, running with Vibram Five Finger shoes, or in a conventional neutral protective shoe (7). The authors of this study found that stride length and stride frequency were lower and higher when running barefoot compared to wearing the Vibram Five Fingers and conventional running shoes. Furthermore, there were significantly lower values of peak vertical force at impact while running barefoot compared to running with standard running shoes. Compared to running barefoot, stride frequency was lower while running in the Vibram Five Finger shoes. Stride frequency was 91.2 strides per minute while running barefoot compared to 88.3 strides per minute while running in the Vibram Five Fingers. There was a trend for the stride frequency to be higher while wearing the Vibram Five Fingers (88.3 stride per minute) compared to conventional running shoes (86 strides per minute). Furthermore, of interest is the authors found a difference in peak vertical force at the impact across conditions. The peak vertical impact forces were 1.59 times body weight while wearing Vibram Five Finger shoes, 1.62 times body weight while running barefoot, and 1.72 times body weight while wearing conventional running shoes. The impact forces were statistically significant lower while wearing the Vibram Five Finger shoes compared to running in conventional shoes (7).

In looking at how the foot strike occurred, it was found that the foot strike occurred similar in the Vibram Five Fingers to barefoot running in that the foot was more plantarflexed compared to the conventional running shoes. This leads to more of a forefoot strike compared to the rear-foot strike that is common while wearing running shoes. This leads to reduced impact forces on the heel of the runner.

An important finding in this study (7) is running with the Vibram Five Finger Shoes led to a significant decrease in oxygen consumption compared to the conventional running shoe. Values of oxygen consumption were similar between barefoot running and running while wearing the Vibram Five Finger shoes.

The authors concluded that the Vibram Five Finger shoes are an effective means to imitate barefoot running and provide protection. This protection allowed the runners to push off more vigorously compared to barefoot running. Evidence for this is the higher pressure under the metatarsal head, higher step length, lower step rate, and higher thrust peak force compared to barefoot running. It appears the Vibram Five Finger Shoes offer the benefits of barefoot running, while offering the protection of a running shoe (7). Furthermore, running in Vibram Five Finger shoes does improve running economy, and this is appears to be due to a combination of decreased shoe weight (compared to conventional shoes) and running gait that is similar to barefoot running.

To summarize up to this point, it may be that fast runners adopt a fore-foot strike pattern to avoid the high impact forces that would occur with a rear-foot strike. Furthermore, the fore-foot strike mimics barefoot running, which is known to improve running economy. While the fore-foot strike, reduces the braking action that occurs with a rear-foot strike (heel strike), this author will acknowledge part of the improved running economy associated with barefoot running is partly due to lack of shoe weight. Running economy improves .5-1% for every 100 grams of reduced shoe weight (1)

In writing this article, a similar article appeared in Triathlete Magazine that put the blame of increased running injuries on the barefoot running phenomena on minimalist shoes and barefoot running, despite the fact that injuries rates in runners have remained stable despite the advent of shoes with more cushion and motion control (6). I decided to ask an expert in the field, Gina Ponegetti, MPT, MA, CSCS, at Accelerated Rehabilitation. Here are her thoughts:

1) I love Vibrams, I agree that they make the intrinsic muscles of the foot and foot stabilizers work. They allow the pronation that happens naturally and work the supinators to get the person out of that position upon toe-off phase of gait. They inherently also then work the hip rotators (external rotators work eccentrically upon pronation phase of gait and concentrically upon the latter phase of gait to un-pronate). In shoes that are too stable, as American's tend to have, it disallows any motion of the foot (i.e. stiff orthotics, over-corrected people in pronation control and orthotics and medial arch buildups)
2) grass is best, for shock absorption
3) in the overweight, new runners, over-runners, etc., they are more likely for any injuries. But especially in Vibrams. Typically, 1) plantar fasciitis, 2) sesmoid irritations, 3) neuromas, and 4) “perceived” tendinitis, which is really just overworked tendons and muscles that are not used to working as hard in the supportive shoes and need to get used to it, or … the muscles themselves are weak and Physical Therapy exercises are needed to strengthen these for proper foot support (i.e. lateral peroneals, medially the posterior tibialis and flexor hallicus, as well as occasionally the popliteus and plantaris, since they are involved in tibial torsion/rotation which happens more in Vibrams due to subtalar and talar/crural joint motion).

So, should you try the Vibram Five Fingers? The answer really depends on the individual athlete. The most important considerations are the biomechanics of the athlete as well as body composition. While being a heavy pronator does not necessarily preclude one from running in minimalist shoes, such as the Vibram Five Fingers, extra caution is warranted and extra work should be performed to increase the stability of the runner, i.e. ankle strengthening and stability, as well as improved core strength (in particular hip abductor strength). If one is carrying extra body weight, I suggest first focusing on increasing the percentage of lean body mass, thus decreasing the amount of impact that occurs while running in minimalist shoes. While Vibram Five Finger shoes have been shown to decrease the impact forces, there is still very little cushion compared to conventional shoes to protect one from the impact forces that do occur.

If you decide to run with the Vibram Five Fingers, it is critical that you ease into the shoes (please also see my blog at http://coachbrett.wordpress.com/2010/06/30/vibram-five-fingers-2/). The first run in them should only be about 5 minutes. One way to ease into them is to run for five minutes and then switch back to your regular running shoes for the remainder of the run. Then each week, add a couple of minutes to each run with the Vibram Five Finger shoes. Once you have reached about 30 minutes of continuous running in the Vibrams, then increase the volume by 10-15% of each run that involves the Vibram Five Finger shoes. Of course, there will be run workouts that do not involve the Vibrams. Depending on the length of the long run, you may want to complete your entire long run of the week in your regular running shoes. Furthermore, due to the increased thrust peak vertical forces (how hard you push off) and corresponding increase in peak pressure on the metatarsal heads (pressure on the balls of your foot), I would hold off on wearing the Vibrams for track workouts until you are completely comfortable in them. The bottom line is moderation is key. Take your time getting used to them!

In conclusion barefoot running and running in minimalist shoes decrease the impact that occurs during running, increases running economy (as shown in decreased oxygen consumption at a given running speed), and may decrease the likelihood of injury. However, patience is warranted, and one must transition slowly to minimalist running.

1) Burkett LN, Kohrt WM, Buchbinder R. Effects of shoes and foot orthotics on VO2 and selected frontal plane knee kinematics. Med Sci Sports Exerc. 17:158-63, 1985.
2) Hasegawa H, Yamauchi T, Kraemer WJ. Foot strike patterns of runners at the 15-km point during an elite-level half marathon. J Strength Cond Res. 21:888-93, 2007.
3) Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D'Andrea S, Davis IS, Mang'eni RO, Pitsiladis Y. Foot strike patterns and collision forces in habitually barefoot versus shod runners. Nature. 463(7280):531-5, 2010.
4) Milner CE, Ferber R, Pollard CD, Hamill J, Davis IS. Biomechanical factors associated with tibial stress fracture in female runners. Med Sci Sports Exerc. 38(2):323-8, 2010.
5) Pohl MB, Hamill J, Davis IS. Biomechanical and anatomic factors associated with a history of plantar fasciitis in female runners. Clin J Sport Med.19:372-6, 2009.
6) Richards CE, Magin PJ, Callister R. Is your prescription of distance running shoes evidence-based? Br J Sports Med. 43:159-62, 2009.
7) Squadrone R, Gallozzi C. Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners. J Sports Med Phys Fitness. 49:6-13, 2009.

Coach Brett can be reached at coachbrett@petersenperformancelab.net
www.petersenperformancelab.net

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