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.
I am the lucky owner of several congenital misalignments in my feet and spine, but I have a large engine that allows me to run fast despite my large frame. Keeping myself healthy has been a solid challenge throughout my career and it still is, despite a very determined effort to remain injury-free. I have tried a lot of different combinations of shoes and orthotics. In later years, I also tried a gradual adaptation to a more minimalist approach, but I’ve never succeeded in finding a single solution. Rather, I have come to believe that staying injury-free is an ongoing process in which initiatives to improve body function and awareness must go hand in hand with the desire to train longer and harder. The barefoot idea seems to demand a greater focus on this balance, which, when compared with the shoe tech focus, is even better, but there are still many more things to consider.
An overuse injury is always a matter of overtraining. An injury never occurs out of the blue. It occurs because the body was stressed more than it was ready to handle. Often we have a tendency to think of our body and mind as absolute in nature. We have a certain build and a certain technique for running; we have a certain character and certain traits that are part of us, good or bad. We are constructing a static vision of ourselves and who we are.
In the real world, however, our bodies and minds adapt to what we put them through. After doing your first Ironman, your perception of what is possible to achieve goes through the roof most likely because your mind adapted throughout the process of overcoming numerous obstacles in the preparation for and during the race. Our body functions the same way, constantly adapting over time to the challenges we endure. So rather than looking for quick fixes, we should see improvement and injury prevention as a cyclic, ongoing process.
How this process leads to either superior performance or breakdown was elegantly conceptualized by the Hungarian scientist Nikolai Jakowlew in 1967. His theory of supercompensation is one of the most basic principles for training and changes in body function. If you are able to apply this model in real life, you are basically guaranteed success, but it will most likely take you the better part of a lifetime to fully understand the practical application.
Jakowlew starts by stating that any kind of activity puts a load on the body. In fact, any training we do breaks us down. Energy stores are depleted and small tears occur in tendons and muscles. We get tired. Once we stop activity, we enter the recovery phase. If we allow adequate rest and sufficient nutrients, the body, will gradually recover to its starting point. Given more time, it will actually supercompensate and grow just a little stronger. Tendons and muscles heal and strengthen while energy stores grow a tad bigger. The body will see an increase in fitness after several successive sessions in which the amount of training stress and recovery time are planned so that every new session occurs at the height of supercompensation. If, however, the recovery window is too short and you engage in a new training session before supercompensation occurs, you will start a downward slide in your training.
While this is an elegantly simple model in theory, it holds multiple practical challenges. First, the training stress and recovery times of different body structures are extremely varied. While the circulatory system and our muscles respond rather quickly, our tendons and ligaments require far longer recovery time because of minimal blood flow to them. In an ankle sprain, it takes a full nine months for the ligament to regain its normal strength, while muscle tears heal in just a few months.
This principle becomes relevant when discussing overuse injuries in running. The injured part of your body was not allowed adequate time for recovery. In many cases I believe we can adapt to anything, whether big cushioned soles or no shoes at all. It is just a matter of how long it will take. Hence every injury is due to lack of patience and adequate response to what your body is telling you.
In this thematic context, injuries are not related to wearing shoes or not wearing shoes. Injuries are connected to taming our eagerness to improve and, increasing our knowledge of what we can do to become better and understanding that the body does not change or adjust in a week or a month. It takes many months for small changes to occur, and it takes years to make radical changes—there is no easy way.
Developing Better Running
If one were to consider the optimal path to better running in light of the current discussion, then, what would be “optimal”?
Besides developing the fitness side of performance through increased VO2 and thresholds, we must aim at the most efficient technique and the equipment that gives the least reduction in this efficiency. Unless, that is, we can actually improve performance through a spring-like system that gives a better energy return than the tendons in the body or the shoe. Such a system is yet to be invented, even though the prosthetics of the double amputee South African Oscar Pretorius definitely stirred discussion on this topic.
Ideally we can look at the running elite, who are the result of a long, fiercely competitive selection. They all land on the forefoot, striking under the center of mass with a long powerful back kick, while keeping torsos stable and upright. They are often small in size and have run since childhood. They wear very light shoes and would most likely do equally well without shoes, as history has demonstrated.
Obviously, the rest of us have not run for miles each day on our bare feet since early childhood, we often weigh a lot more than 100 pounds and we have far from the adequate muscle and tissue strength, control or flexibility to run with optimal technique. In fact, we often find that we are best at what we are adapted to. So if you have been heel striking in shoes for 15 years, you might be most efficient and injury resistant in that pattern. You will mostly likely know your exact spots of weaknesses, and you can then try to assess and correct these. Over time, you can work toward a better technique or improving your body function, but it’s a very long process and will test your patience.
For each little step you take forward, it will take a long adaptation period for you to see the effect, so to repeat the mantra: There is no easy way.
Five Steps to Injury-free Running and Improved Performance
1. Always adjust training load to the feedback from your body. If you at any time feel soreness that occurs during, directly after or the morning after any training session, you must take a step back, assess and build back up. Training soreness in muscles can be accepted to some degree, but any dull pains, stiffness or irritation near any of your joints or ligaments should be a big, red warning light. Remain relaxed about your plan and never train with pain.
2. Improve body function. In the last issue of Inside Triathlon I wrote a piece on the importance of strength, flexibility and motor control in the ability to execute perfect form. This is probably your most secure shortcut toward injury-free running as you address your specific weak links. Short barefoot runs can be a great way to do this, but specific foot, lower limb, core stabilizer and balance training is a necessary component as well.
3. Find the minimal shoe solution that works for you and avoid heavy tech shoes. Your personal history will tell you what you are accustomed to and where you can start in terms of judging your need for shoes or no shoes. Runners who are used to minimalist shoes will have strong feet, but others should aim at moving away from shoes with too much support and high-profile soles over time, as they might hurt rather than help. Always adjust in gradual steps and look many months—or even years—ahead in your planning. Remember, your connective tissue adapts in upwards of nine-month cycles. If you want to try the barefoot option, expect a long adaptation period before you can perform at your peak in bare feet. Start with one- to three-minute easy runs and build very slowly from there. If you have anatomical abnormalities in your feet, orthotics can be used, but they will not reduce your need for strengthening and balance.
4. Reduce weight of shoes (and body). Shoes are constantly put through deceleration and acceleration during running. Therefore, lowering the mass of shoes is very important for performance and optimal mechanics. Over time you should aim to run in very light flats or no shoes at all when you are strong enough. The lighter and stronger you are, the better mechanics you have and the more you can work toward minimalist shoes or no shoes at all.
5. Work on optimal form. Building optimal body function is the first step, but as you extend your range of motion, become stronger and can control leg and spine alignment while running, you can start improving your form in the image of running legends such as Haile Gebrselassie. Moving toward high-frequency steps, striking on your forefoot under your center of mass while maintaining spine control and upright stable torso could be a few key points to work on, but remember to take it one step at the time. The hard part is the patience.
Sindballe is a former ITU long course world champion and podium finisher at Kona.