The Natural Running Center is privileged to republish this article, “What Can We Learn from Watching Children Run?”,  by Dr. Irene Davis, which originally appeared in the Fall 2011 Journal of the American Medical Athletic Association. Dr. Davis is one of the world’s leading experts on running mechanics, running injury, and research. Dr. Davis and I spoke with Dr. Dan Lieberman at the annual American Medical Athletic Association 2011 meeting at the Boston Marathon.  We will return to the AMA event this April.

Dr. Davis is at the forefront of change — towards a world of better shoes and improved running form. She conducts research studies, asks the important questions, teaches large community groups, classrooms, and treats individual runners in her clinic.  She has published convincing work that states by simply teaching yourself to land softer (via visual feedback) you can reduce loading rates associated with stress fractures. Dr. Davis is Director of the Spaulding National Running Center and is a Faculty Member in the Department of Physical Medicine and Rehabilitation, Harvard Medical School. She has also  been featured on ABC World News Tonight, Good Morning America, Discovery, the New York Times, the Wall Street Journal, Parade and Time.

I’d like to conclude this brief introduction to Dr. Davis with this quote by her that appears on the Spaulding Rehabilitation Center website: “We seldom prescribe a neck brace as a permanent solution for neck pain, and yet it is not uncommon to prescribe a permanent foot brace (orthosis) for someone with foot pain. I firmly believe the approach we take with orthotics on the foot needs to be reexamined. My research has led me to consider that by encouraging minimal footwear we actually make the foot stronger over time.The human body is a remarkable machine and is engineered to perform without the need for $200 running sneakers.” –Dr. Mark


What Can We Learn from Watching Children Run?

By Irene Davis, PhD, PT, FACSM, FAPTA, FASB

It has been suggested that running is naturally innate in us as it was a means of survival. Natural running can be defined as running in the way we were designed for. This can be best observed when one is running without the interference of shoes or braces. Observing the gait of a child,who has not habituated into shoes, provides a window into the development of natural gait. When a child first walks in a pair of supportive shoes, after toddling around barefoot, it is very unnatural and awkward. This is not surprising, as their shoes have disrupted the natural inertial characteristics of their leg. In addition, shoes have added unnatural lever arms of the ground reaction force, increasing external moments thatchildren now need to control.

When children first learn to run, they naturally land on their forefoot with a relatively flat foot pattern (6). Bythe time they are four years old, and likely habitually shod, they have adopted a rearfoot strike pattern when they run. A habitually barefoot runner will also strike the ground with a fairly horizontal foot. They land on the lateral ball of the foot, with the heel slightly off the ground. The heel then lowers to the ground in a foot-flat position and the foot then plantarflexes for pushoff.

Habitual barefoot runners do not land on their heel for the very reason that it hurts. If running were essential to our survival, then it makes no evolutionary sense that we would run in a way that is painful. The pain associated with a barefoot heelstrike is related to the high impact transient that is associated with a rearfoot strike pattern. This very quick rise to peak in the vertical ground reaction force curve results in a high rate of loading experienced by the body.

The body is comprised of viscoelastic structures, which are sensitive to rates ofloading. If these loading rates are high, these structures may not have time to adapt to the load.This can result in pain and, with time, injury. Heelstriking in modern cushioned running shoes is not painful; in fact, it is comfortable. However,the impact transient is still very present. This impact transient has been associated with a varietyof running-related injuries both retrospectively and prospectively (18,11,12,3).

Running barefoot, or in shoes that do not make it comfortable to land on one’s heel, results in a more anterior strike pattern. This strike pattern is seldom associatedwith an impact transient (8,17) and thus is likely to reduce injury risk.

There are other reasons to consider running barefoot or in minimal footwear. No one would argue with the fact that a strong foot is more likely to be a healthy foot that is more resistant to injury. It has been shown that when individuals remove their shoes and go barefoot, or run with shoes without any arch or rearfoot support, their feet become stronger (13,2).

Our feet are remarkable structures with 26 bones, 33 joints,and 30 muscles. They were designed for all of the locomotor demands of our ancestors, including running. The arch itself has four layers of muscles, which are critical to controlling the deformation of the arch as we load it. These muscles are the first line of defense for the plantar fascia, which lies directly below these muscles.If those muscles are unable to adequately control the lowering of the arch, the plantar fascia becomes excessively strained. With enough repeated loading, plantar fasciitis ensues. It is, therefore, not surprising that plantar fasciitis is the most common foot injury that clinicianstreat.

With increasingly supportive footwear, we have conditioned our feet to be lazy.We are often misled into believing that cushioned running shoes soften our landings. Theydo indeed make it more comfortable to land on our heels; however, there is evidence that demonstrates we adjust our leg spring to the surfaces we land on. For example, a study by Bishop et al (1) revealed that knee stiffness was significantly increased when landing in a highly cushionedrunning shoe, compared with a low cushioned shoe or in bare feet. Knee stiffness has been associated with greater rates of loading duringlanding (10).

While it may seem counterintuitive that you land harder in softer shoes, this relationship between landing behavior and surface hardness is well supported by other research, as well (9,4,5). We highly underappreciate that our feet areremarkable sensate organs. There is a wealth of sensory input from our feet that is critical tonormal function. These sensory signals provide important information that assists with balance and stability. It has been shown that even a thin pair of socks negatively influences static standing balance (15). Wearing socks on your feet while you perform functional activities is not much different than wearing gloves on your hands during daily activities. Our recent research on single leg landings has demonstrated that dynamic stability is also significantly decreased in standard running shoes compared with bare feet (14).

Modern running shoes with elevated cushioned heels, arch support, and stiff heel counters interfere with the natural movement of the foot. Shoes were originally designed to simply protect the bottom of our feet, not replace foot function(16). Seldom are we successful at improving on nature. Therefore, the move towards more minimal footwear that has no cushioning or support is very encouraging.

While there is much to learn from watching children develop, perhaps there is even more to gain from studying those who have grown up barefoot. If children grow up never wearing shoes, they mature into forefoot strikers when they run (8). However, if they grow up wearing modern running shoes, most (75%) mature into rearfoot strikers when they run (7).

We cannot disregard that one significant difference is the shoes. For those who have been habitually shod in modern cushioned and supportive running shoes, a slow transition to barefoot or minimal footwear is requisite. However, this patience will pay off with stronger feet and reduced impacts experienced by the body. For those runners with intact neuromuscular systems seeking a stronger, healthier foot and more natural running pattern,less will truly be more.



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