If you walk into a sports store today, the number of running shoes for sale is overwhelming. Since its inception, the running shoe has evolved and the technology has improved to the point where many running stores are now able to video analyze how you run and recommend the perfect running shoe, based on gait, pronation, and width of your foot. But it wasn't always this way.
As a matter of fact, before 1970, and the previous two million years or so, humans did not have the benefit of the heel-cushioned running shoe, the creation of which has caused us to completely change how we run.
The majority of shod runners, or runners wearing shoes, strike the ground with their heel and the mid-foot and forefoot landing a split second later. Heel-strike running is a relatively new phenomenon. To see how, all you have to do is take your running shoes off. Quite painful, right? As a result, the body naturally adjusts to a mid-foot strike or forefoot strike.
The reason the body naturally uses a mid-foot or forefoot strike can be found in the bio-mechanics of the foot.
The human foot is shaped like an “L”. On the back of the “L” we have our Achilles tendon and calf muscles, and on the front we have the muscles of the foot. Additionally, we have vertical rotation of the foot around the ankle. To see this, point your toes down, then, bring your toes up towards your shin. Total range of motion is anywhere from 30 to 80 degrees.
Essentially, we have springs in our feet that allow our “L” shaped base to absorb the impact of our bodies landing on the ground and pushing back off again. The heel-strike negates the spring-like bio-mechanics of the foot and transfers the impact of landing to the thick cushion of the shoe, and the joints of the body.
Can You Feel It?
The reason running shoes have such thick soles is to accomplish what the bare foot does naturally; take the impact away from the ankles, knees, and hips.
“By landing on the middle or front of the foot, barefoot runners have almost no impact collision, much less than most shod runners generate when they heel-strike,” according to an article by Harvard researcher Daniel Lieberman and his research team in the journal "Nature".
Impact collision is the initial force of the body landing transferred up through the body. Lieberman adds that when a barefoot runner strikes the ground, the impact collision is not absorbed by the heel and transferred to the ankle, knee, and hips, but is changed to rotational energy of the pointed foot touching the ground and with the help of the calf muscles and Achilles tendon, slowing the impact and easing our landing.
"The average runner strikes the ground 600 times per kilometer, making runners prone to repetitive stress injuries," according to the article. "The incidence of such injuries has remained considerable for 30 years despite technological advancements that provide more cushioning and motion control in shoes designed for heel-toe running.”
Weak below the knees
Last summer, Stuart Warden, an associate professor and director of research in the Department of Physical Therapy at Indiana University-Purdue University Indianapolis, conducted the symposium “Barefoot Running; So Easy, a Caveman Did it!” at the 2011 American College of Sports Medicine meeting in Denver, Colorado.
“The heel cushions and arch supports within modern shoes have made our feet weaker,” Warden said.
This is true of any biological process in the body, if you don’t let the body do it, it will atrophy. This is understood to be an adaptive process that eliminates unnecessary or overly redundant biological functions. If you’ve ever worn a cast, you remember that when you took the cast off, the muscle underneath had atrophied.
Wanna go for a fun run... Barefoot?
Lieberman theorizes that around two million years ago the human foot changed from a flatter arch to a higher, springier arch allowing humans to improve long distance or endurance running.
Endurance running may have given humans an edge over other animals in the search for food is a possible explanation for this evolutionary change. Whereas quadrupeds or four-legged animals are much better sprinters, giving them an apparent evolutionary advantage, a bipedal or two-legged animal that could not necessarily sprint but could sustain a decent pace and ultimately tire the quadrupeds out and kill their prey.
In my opinion, combining the bio-mechanics of the foot with historical evidence and evolutionary context provides a solid case for the potential health benefits of barefoot running.
Watch out for that broken beer bottle on the ground!
I, however, do not run barefoot. I wear five finger shoes or Gorilla Feet, as I like to call them. Currently, the only company I am aware of that sells them is Vibram. I have no financial interests in this company. These Five Finger shoes preserve the biomechanics of the foot while providing protection from glass and rocks that one may encounter on the road or sidewalk.
Ultimately the choice is yours whether to run in heel-cushioned shoes or gorilla feet. If you enjoy running in heel-cushioned shoes and are not experiencing any discomfort I would recommend you continue to do so. If you are experiencing discomfort while running and would like to try something new, please be careful.
I know from personal experience that if you push your workout too far in Five Finger shoes, you can pull or tear the weaker, less used muscles needed for barefoot running and cause delays in your training. On the Vibram website, you can find a practical guide to transition from traditional running shoes to Five Finger shoes, and, as always, check with your doctor before making and major changes in your exercise routine.
Important Disclaimer: The idea that running shoes may be making our foot and leg muscles weaker also explains why it can be so difficult to transition to barefoot running. Transitioning from running shoes to bare feet can take weeks to months to years. When transitioning, consider running one-tenth of your current distances with one-three days of rest in-between.
(This column is for informational purposes only and is not a substitute for medical advice, diagnosis or treatment.)