sábado, enero 26, 2013

Can Barefoot Running Improve Performance?


Rasmus Henning and Michelle Vesterby - Kona 2012 part 5

ECCO BIOM Athletes Rasmus Henning and Michelle Vesterby did a tremendous job at the World Championghip. Michelle finished 12th on her Kona debue, while Rasmus finished off his carrer with a respectable 22th place. A big congratualtions from everyone at ECCO!


Written by: Torbjørn Sindballe


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 Run-olution.

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.

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.



Why Barefoot Runners Never Win

Have you ever seen a barefoot runner win a race? No, you probably haven’t. A study reported in Medicine & Science in Sports & Exercise may explain why. Researchers at the University of Colorado found that, despite the claims of barefoot enthusiasts, running with cushioning is actually more economical than running shoeless on a hard surface.

Unlike past studies comparing the energy cost of shod and unshod running, this one controlled for important factors that may have biased earlier results. These factors included barefoot running experience, foot strike pattern, shoe weight and running speed.

Twelve male runners participated in the experiment. All were experienced barefoot runners and mid-foot strikers. The subjects ran at a fixed pace of roughly eight minutes per mile on a treadmill under several conditions: barefoot (actually, wearing very thin socks for hygienic reasons), wearing super-light (5.3oz) Nike Mayfly racing flats, and with various amounts of weight attached to their bare feet or to their shoes. Oxygen consumption was measured to determine the energy cost of each condition.

Interestingly, the energy cost of running with and without shoes was roughly the same. But when an amount of weight equal to that of the racing flats was attached to their bare feet, the runners used 3 to 4 percent more energy than they did in their Nikes. In other words, when weight was controlled for, running barefoot was less economical than running in lightweight shoes.

“These results got us thinking,” says Rodger Kram, the study’s lead author. “If lightweight shoes have the same energy cost as running barefoot, then there must be something good about shoes that’s counteracting the negative effect of their mass. We suspected that it was probably cushioning.”

To test his hunch that a cushioned landing surface saves energy otherwised used to soften foot strike when barefoot, Kram and his colleagues designed a follow-up experiment in which subjects ran barefoot on a cushioned treadmill. Sure enough, the runners used 1.7 percent less energy on a treadmill whose belt was cushioned with 10mm of the same kind of foam that is contained in running shoes than they did on the non-cushioned belt.

According to Kram, who recently presented his findings at a meeting of the American Society of Biomechanics, the take-home lesson is that, for maximum running performance, not only are shoes better than no shoes, but shoes with a little cushioning are better than minimal shoes, despite a bit of extra weight.

“If you’re really trying to save seconds,” he says, “lighter isn’t always better.”


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