Quick Hit Summary

The newest training craze in the fitness world today is barefoot or pseudo barefoot (Vibram FiveFingers®, Nike Frees®)training. Barefoot training forces athletes to land on the balls of their feet when striking the ground. In contrast, individuals tend to strike the ground with their heels while wearing shoes. Research indicates that striking the ground with the balls of your feet vs. heels, reduces initial impact as well as the load felt by your knees and hip. Thus, it may be effective at preventing osteoarthritis of these joints. In addition, barefoot training strengthens the intrinsic muscles of the foot, possibly preventing injuries such as plantar fasciitis. Although barefoot training appears to have many benefits, I’m obligated to mention that long term studies are still required to support these initial findings. That being said, I strongly encourage you to work barefoot training into your exercise routine. Kick off your shoes while resistance training, moving about the house, etc. However, for endurance runners, I caution you against taking it to fast, as this may cause injury. Please refer to the advice of Harvard researcher, Dr. Daniel E. Lieberman, when implementing barefoot or pseudo barefoot training into your routine.

Barefoot Training

Every few years, a new fad seems to take hold in the fitness community. A few years back, unstable surface training was the rage. {Check out my interview with Christian Carter for my thoughts on the topic}. The “next” big thing I see working its way into the fitness industry is barefoot training. Although I refer to it as “next”, barefoot training has actually been around for awhile. If you look at vintage photos of Arnold Schwarzenegger & friends, you’ll notice that they often trained barefoot. Additionally, elite training centers, such as Athlete’s Performance, have long had their athletes go barefoot while completing lower body exercises (squats, deadlift variations, etc).

Figure 1. Notice Arnold’s buddy squatting without shoes.¹¹

The rising popularity of barefoot training is not restricted to the resistance training community. It has recently gained popularity in the running community thanks to strong endorsements from Christopher McDougall, author of Born to Run and Harvard researcher, Dr. Daniel E. Lieberman. In response, shoe companies have began to heavily market pseudo barefoot shoes such as Vibram FiveFinger® and Nike® Frees to exercise enthusiast.

In my experience, proponents of barefoot training, especially endurance athletes (sorry if this generalization offends anyone), speak of it in an almost holistic/mystical sense. They love the organic, natural feel of barefoot training. Furthermore they claim that wearing modern shoes, with little flexibility (ie- can’t twist it along long axis and unable to flex it at multiple locations), may actually weaken our foot muscles and increase the risk of injury.

Is the above true? Should we ditch our traditional gym shoes and go barefoot? Before we make this decision, let’s examine the evidence supporting and/or refuting barefoot training.

The Biomechanics of Barefoot vs. Shod (shoe) running

Figure 2 Barefoot Running along the Beach

As one would naturally expect, footwear greatly influences the way we move. Clear distinctions in foot orientation, upon striking the ground, and stride length are present between conditions. When wearing shods (shoes), one tends to takes long strides and land on their heels (ie— rear foot strike (RFS)¹. In contrast, when barefoot walking² or running⁴, one’s strides are shorter (~6%⁴) and are characterized by either mid- or front-foot strikes (MFS or FFS). Please see Figure 3 for visual picture of RFS vs. FFS.

Figure 3. As seen in the top picture, front foot strikes, which occurs while walking/running barefoot, leads to a gradual rise in force upon striking the ground. Walking barefoot also leads shorter, but faster strides vs. wearing shoes. As seen in the bottom picture, rear foot strikes, which occur while wearing shoes, are characterized by a rapid spike in impact forces. Please note that this figure does not represent the images of any one specific study. Rather, it’s a general trend seen in most studies on this subject.

Differences in stride length and foot strike position differ for 1 reason. Namely, RFS cause large transient impact forces that must be absorbed either by the body (ie- the heel) or ones shoes. Thus, rather than painfully absorbing the impact through ones heels, barefoot runners generally employ MFS or FFS running strategies. In doing so, large spikes in pressure are minimized as the impact force is more evenly distributed over the foot (See Figure 3). In a study completed by Divert et al., researchers had 31 participants, with no previous barefoot running experience, complete both shod and un-shod running trials. Final results indicated that running barefoot decreased initial impact force by 13% vs. that observed while wearing shoes³. In a somewhat similarly designed study, Squadrone & Gallozzi, found that running barefoot reduced initial impact forces by 5% vs. shod running in 8 experienced barefoot endurance athletes⁴.

Right now you’re probably thinking… “OK, I understand why we don’t want to land on our heels if we are barefoot. However, rear- foot striking is not painful if we have shoes on. Thus, does it really make a difference if we wear shoes or go barefoot?”

Barefoot vs. Shod on Performance Variables

Movement Efficiency during Running

As aforementioned, one has a longer stride when running in shoes vs. barefoot due to how their foot strikes the ground (ie- RFS vs. FFS). To the naïve individual, RFS sound like a good thing… If one can take longer strides, he/she should be able to run faster, right?!? This makes sense assuming that we can maintain stride frequency. However, when running at comfortable endurance speeds (7-8 mph), longer strides are associated with decreased stride frequency¹³⁴. In other words, when running barefoot, we increase the rate at which we take strides. Thus, at endurance running speeds, the effects appear to cancel each other out. In competitions that involve speed (ie- 100 meter sprints), FFS are actually the preferred method of running. This about it… Have you ever seen a sprinter RFS? Of course not! By FFS, they are able to take advantage of the elastic energy found in connective tissue such as the Achilles tendon to propel them down the track. This boost is in addition to the force produced by muscles.

As noted above, FFS are the preferred method of sprinting because it allows you to tap into your elastic energy. By taking advantage of this, our ability to move is obviously improved. If this improved movement efficiency carries over to endurance running is debated. In the previously mentioned study conducted by Squadrone & Gallozzi, each barefoot trained athlete completed three 6 minute treadmill runs (set at a constant ~7.5 mph) under the following conditions:

• Barefoot
• Pseudo Barefoot (Vibram FiveFingers® Classic model)
• Running Shoes

Movement efficiency was measured via VO2 (oxygen consumption). For those not familiar with VO2, it’s a way to measure the amount of energy used to perform a given physical feat. A higher VO2 equates to greater energy expenditure when performing a given task. Thus, if running the same distance, at the same speed, the condition that burns more energy is less efficient. (If trouble grasping this concept, think of 2 cars of the same make & model; the one that burns less fuel to perform a given task is the one that you want in your garage). Final results of the study indicated the following….Despite running the same distance, at the same speed, runners had a significantly lower VO2 (2.8%) while wearing Vibrams in comparison to running shoes⁴. Although a reduced VO2 was measured in the barefoot condition (1.3%), it was not significantly different from the shod conditions.

Resistance Training

To my knowledge, the effects of resistance training in shod vs. barefoot conditions have not directly been studied. However, indirect evidence does support the use of barefoot training to strengthen the intrinsic muscles of your foot. In a study completed by Robbins & Hanna, 17 athletes increased barefoot activity (1+ hrs/day) or continued with their normal footwear patterns for 4 months⁷. At the conclusion of the study, it was found that those who increased barefoot activity had stronger, more “active” intrinsic foot muscles. This was not observed in the group that did not increase barefoot activity. Robbins and Hanna also hypothesize that by strengthening these intrinsic muscles, issues such as plantar fasciitis could be avoided. Although I have a few methodological issues with the study, I do agree with the final analysis—> increased barefoot activity strengthens the muscles of the feet, improving overall foot health. In turn, healthy feet equals healthy movement.

Working Barefoot Into Your Program

Many advantages appear to be present with barefoot training. I’d recommend switching over to barefoot resistance training as soon as you’re comfortable (Just don’t drop any weights… Speaking from experience, dropping a weighted implement onto your bare foot has a little more of an OUCH factor to it!). Also, for around the house type stuff, or going to the store type activities, kick off you shoes entirely or go pseudo-barefoot (ie- Vibram FiveFingers ® Nike Frees ®, etc). As my friend Mike Nelson, PhD candidate, says:

“…the foot has many moving parts and it should be trained in many directions. If we only moved it up and down, there would be simple hinge joint there…Smarter the shoe, dumber the foot. Messed up feet = messed up hips due to the arthrokinetic reflex which roughly translated is code for jammed joints equal muscular weakness. (Editor’s note – when he says smart shoes, he’s referring ones to lots of supports, straps, rigid design, etc) [12]”.

If you’re interested working barefoot or pseudo-barefoot training into your endurance exercise program, I wouldn’t recommend quitting “cold turkey” with respect to your training shoes. Doing so would actually increase your risk of injury as you’d be putting demands on your body that it’s never experienced. For example, one’s calf and Achilles tendon face much greater stresses when barefoot training (due to FFS/MFS vs. RFS that occurs in shoes). In addition, after wearing shoes for our entire lives, our feet are actually misshaped. According to research conducted by K. D’Aou et al., wearing shoes appears to decrease both the length and width of our feet⁹. Thus, your lower body won’t be able to handle the physical demands of barefoot training as well as someone who grew up not wearing shoes. I’m not trying to discourage you from running barefoot, I just want to emphasize that you should BE SMART & TAKE IT SLOW!

With respect to working barefoot training into your endurance training program, I HIGHLY RECOMMEND taking the advice of Harvard researcher, Dr. Daniel E. Lieberman, lead investigator of the famous barefoot study that most advocates rally around in support of the movement¹⁰.

CLICK HERE FOR DR. LIEBERMAN’s RECOMMENDATIONS/TIPS.

Long Term Studies

Short term studies seem to support the idea that barefoot training supports healthy movement. However, I feel obligated to mention that no scientific studies to date have shown that long term barefoot training is better/worse than wearing normal training shoes. More research is still required in this area.

Bottom Line

Although more research still is required in this area, it appears that adding barefoot exercise into your training arsenal may be beneficial for both power and endurance athletes alike. Research indicates that it reduces initial impact at foot strike while simultaneously strengthening the intrinsic muscles of ones foot. In turn, this may decrease the risk of developing painful foot conditions such as plantar fasciitis. I encourage everyone to slip the shoes off while doing “around the house” type of jobs and while lifting weights. However, don’t ditch your running shoes overnight. Heed the advice of Harvard researcher, Dr. Daniel E. Lieberman, and SLOWLY work them into your training program. If you have increased foot pain, STOP!

Stay tuned for Part II of this article where we examine the relationship between barefoot exercise, shoes, specialized inserts and the risk of injury.

Please know that I have no financial or other interest in any of the specific name brand shoes that I mentioned during this article.

References

¹ De Wit B, De Clercq D, Aerts P. Biomechanical analysis of the stance phase during barefoot and shod running. J Biomech. 2000 Mar;33(3):269-78.

² Wolf S, Simon J, Patikas D, Schuster W, Armbrust P, Döderlein L. Foot motion in children shoes: a comparison of barefoot walking with shod walking in conventional and flexible shoes. Gait Posture. 2008 Jan;27(1):51-9. Epub 2007 Mar 13.

³ Divert C, Mornieux G, Baur H, Mayer F, Belli A. Mechanical comparison of barefoot and shod running. Int J Sports Med. 2005 Sep;26(7):593-8.

⁴ Squadrone R, Gallozzi C. Biomechanical and physiological comparison of barefoot and two shod conditions in experienced barefoot runners. J Sports Med Phys Fitness. 2009 Mar;49(1):6-13.

⁵ Divert C, Mornieux G, Freychat P, Baly L, Mayer F, Belli A. Barefoot-shod running differences: shoe or mass effect? Int J Sports Med. 2008 Jun;29(6):512-8. Epub 2007 Nov 16.

⁶ Jungers WL. Biomechanics: Barefoot running strikes back. Nature. 2010 Jan 28;463(7280):433-4.

⁷ Robbins SE, Hanna AM. Running-related injury prevention through barefoot adaptations. Med Sci Sports Exerc. 1987 Apr;19(2):148-56.

⁸ Accessed on June 10, 2010 from: http://www.flickr.com/photos/666_is_money/4083813727/. Creative License http://creativecommons.org/licenses/by/2.0/deed.en.

⁹ K. D’Aou, T.C. Patakyc, D. De Clercqd and P.The effects of habitual footwear use: foot shape and function in native barefoot walkers. Aerts. Footwear Science. Vol. 1, No. 2, June 2009, 81–94.

¹⁰ 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. 2010 Jan 28;463(7280):531-5.

¹¹ Accessed June 10, 2010 from: http://extremehumanperformance.com/blog/category/barefoot-training/.

¹² Nelson, Mike T. RE: VFF and Followups. Message to Sean Casey. June 9, 2010. Email.