Written by: Torbjørn Sindballe
The appealing thought of running as nature intended is a hot topic in the running community these days. Articles, blogs and websites about barefoot running are published every day, and the possibility that we have been misled by a calculating shoe industry to believe that dual density mid-soles, plastic bridges, gels and air bags were the truthful answer to our prayers of injury-free running are an intriguing story to many.
Most recently, the book “Born to Run” by avid ultrarunner and journalist Christopher McDougall has made the barefoot craze explode after its 40-year hiatus from the running scene. While searching for an answer to the simple question, “Why does my foot hurt?” McDougall ended up with the indigenous Mexican Tarahumara people, whose ability to run for days on end wearing only thin leather sandals or nothing at all was a radical contrast to the high-tech paradigm advocated by the running shoe industry. His book is the final installment in a long line of both anecdotal and scientific evidence suggesting that the world of running shoes is not what it seems.
The scientific front is led by renowned biomechanical scientist Peter Brüggemann. I had the pleasure of working with Brüggemann in the development of the Ecco Biom shoe. As I had been accustomed to the terms “cushioning” and “motion control” whenever I mentioned an injury, I was initially rather skeptical of his thoughts. I nevertheless had to bow my head in respect of the overwhelming evidence presented in favor of a more naturalistic approach to running shoes. Throughout the development process, I was able to test the ideas of a more natural approach to running on my own body. While I am still transcending to cushioned heights, I will offer my opinion on running in minimalist shoes, or even barefoot, in relation to preventing injuries and increasing performance.
Barefoot running was invented some 5 million years ago when we distinguished ourselves from the chimps by running and walking upright. Until the early 1970s, going barefoot and wearing minimalist leather shoes were preferred for walking and running. That alone is an interesting perspective on today’s running shoe technology, as humans have both walked and run for some 4,999,960 years without it. In 1972 Nike launched its first cushioned shoe with the waffle sole, thereby kick-starting the technology focused shoe paradigm we have witnessed ever since.
On the elite running scene, bare feet are old news. In the 1960s Abebe Bikila of Ethiopia won the Olympic gold medal in the marathon in bare feet. Over the following decades other runners such as South African Zola Budd resisted the tempting offerings from the shoe industry and followed her natural instinct to run barefoot. Recently, greater interest has been focused on the Kenyan domination in distance running, and while Kenyans have usually worn shoes in races because of large sponsorship agreements, most of them have grown up running on their bare feet to from school some 10-plus miles every day.
In the scientific community, there has also been an interest in the effects of wearing running shoes. Harvard University paleoanthropologist Daniel Liebermann has researched differences in gait between habitually barefoot runners in Africa and habitually shod runners from the Western world. His research indicates that shoes alter the strike pattern toward a larger percentage of heel striking. Upwards of 75 percent of shod runners are heel striking while the trend is rarely seen among barefoot runners in Africa. Liebermann´s research also shows that when habitually shod runners drop the shoes, their gait pattern changes toward a more “natural” fore- or mid-foot strike. Heel striking moves the shock dampening to the knees and hips and decreases the ability to use the natural elastic springs we have in the large Achilles tendon and underneath the foot. When overstriding, heel striking even presents a braking force to our forward movement, increasing the unnecessary stress on our body. Despite these observations and theories, there is still no direct evidence that heel striking is the cause of injuries.
Brüggemann and many other scientists have spent 25 years researching the effects of running shoes and the heavily promoted technologies of cushioning and motion control. Interestingly, these technologies have had no effect on the frequency of running injuries since they started recording injury rates in the 1980s, and numerous studies have failed to prove the promised effect of cushioning midsoles and antipronation technologies on foot mechanics. The cushioning rarely decreases the load on the body, and the ability to decrease pronation is unseen when measuring bone movements inside the shoes. In fact, the body is fully capable of reusing the energy shock from the foot strike for forward motion, and it is very unclear whether there is an optimal neutral foot stance.
In addition, scientists have found several potential negative effects of shoes. The heel strike and the increased landing height in shoes with a high midsole alter and lengthen the external levers around the joints, so that the muscle needs to work harder to control the landing and standing phases. The weight of the shoe causes the muscle on the front of the shin—the tibialis anterior—to work harder preceding landing and also forces the foot to land more supinated, which might induce a larger unnatural degree of pronation in the stand phase. The built-up soles of the shoes prevent many of the foot’s normal movements such as adequate toe flexion and arch movements, so that the shoes will gradually decrease the strength of stabilizing muscles and tendons and inhibit their propulsive function.
In 2001 physiotherapist Michael Warburton wrote a well-documented report on the effects of wearing running shoes and concluded that while there is no direct evidence to support the claim that shoes increase the risk of injury, there are indications of it in several studies. A 1991 study found the prevalence of injuries in wearers of expensive running shoes to be twice as high as in wearers of cheaper running shoes, which led him to call the deceiving postulations from the industry “a public health hazard.”
Warburton also looked into the potential decrease in running economy because of the added weight of shoes, and found evidence suggesting that regular training shoes increased the oxygen consumption by upwards of 3 percent to 4 percent, even at lower speeds. This is a huge difference that would amount to more than five minutes for an elite marathoner. While the difference is most likely less for the lightest racing flats, it would still be an issue. The only benefit of shoes, then, seems to be the obvious protective effect when walking or running on rough surfaces and in cold or hot climates.
While shoes have not been shown to reduce injury frequency, custom orthotics help relieve injury pain in 40 percent to 70 percent of runners with abnormal foot function. However, this does not help those with healthy feet. The reason why orthotics don’t have the same effect on healthy runners is somewhat unclear. There seems to be a complex interaction between the shoe and insert and the body’s perception of movements.
This cascade of anecdotal and proved evidence is setting the scene for the recent trend of barefoot running and promotes a healthy discussion. But many key pieces are missing from the puzzle. There is no study that directly proves that wearing highly cushioned and motion-control shoes increases the risk of injury, nor are there studies showing that running barefoot reduces risk of injury. While there are many indications suggesting the above, optimal studies of the role of shoes in injury prevention are extremely expensive and difficult to carry out, as they require a longitudinal approach in which a large group of runners are monitored over many months or years. Also, another large part of the puzzle is missing because of the adaptive nature of the human body. We cannot just change from running shod to running barefoot in a day; it takes months, if not years, to strengthen the function of muscle tissue to the changed load.
This might touch the very center of this discussion, because the notion of injury prevention is limited to the shoe alone and also to the idea that injuries can be resolved with a quick fix—something you can buy and apply easily—which is a very narrow-minded approach. In fact, I would dare to claim that injuries are not so much determined by the shoes.