Barefoot Running, or Just a Minimalist Shoe?
By Ben Pearl, DPM
Mention barefoot runners and most people's first association is probably the legendary
1960 Rome marathon victory by Abebe Bikila. To some advocates the conversation can
get heated up quickly as if you were talking about politics. The fundamental question that
has yet to be fully answered is whether one can accurately track a population of runners
who are barefoot vs. shod.
From the Savannah to the Track
Anthropologists such as Daniel Lieberman believe that the human foot developed to run
barefoot. His hypothesis is that we were built for endurance running. Prospective studies
and randomized controlled trials of barefoot and shod running are difficult to achieve for
obvious reasons. Robbins and Gouw argued that plantar sensation induces a plantar
surface protective response whereby runners alter their behavior to reduce shock. The
less-cushioned shoe permitted increases in plantar discomfort, a phenomenon that they
termed "shock setting." Coaches such as Brooks Johnson and Vin Lananna have used
barefoot running as part of an overall program to train the body to run long distances fast.
In their opinion, to run properly, the foot needed to grasp and release on a variety of
surfaces such as dirt, grass, road, concrete, and gravel.
The Shoe Industry Steps in
Several companies have weighed in with their versions of a running shoe which simulates
barefoot running. Adidas’ approach was to try and copy the shape of the foot. In theory
this will produce smaller lever arms that react faster. The idea for the Nike Free was born
out of a visit by a couple of researchers to Stanford where Lananna was having athletes
running barefoot as part of their training regimen. Many competitive runners I spoke to
use barefoot running or shoes like the Nike Free as part of their training. Nike had
students test it for 6 months and those using the Free for 6 months had greater flexibility
and strength in the foot.
I interviewed researchers Tobie Hatfield from Nike's Innovation Kitchen and Jeff
Pisciotta from the Nike Sports Research Lab to find out how the shoe industry has
incorporated the concept of barefoot training into their shoe design. They seem to be
spearheading the shift back to their spirited roots to the old Bill Bauerman days when
they made prototype soles on waffle irons. They studied 20 competitive runners on grass,
and kinematics analysis demonstrated a general trend towards full foot contact. If you
watch the footage of Abebe Bikila's Rome marathon you will notice the same thing. The
perception of some of the runners tested was that they were landing more toward the
forefoot than they actually were.
Many believe that racing barefoot is difficult unless you have been running without shoes
all your life. Many recreational runners are also starting to try barefoot running in an
effort to prevent injuries and improve technique. The problem with this is that some of
them will not have the conditioning to handle the transition to barefoot running. Experts
in the field agree that any transition to barefoot running be done slowly.
The Cushion Illusion
The running shoe industry has built much of its platform on cushioning. The theory goes
that very soft shoes will bottom out when loaded, producing higher impact forces than
firmer shoes that do not bottom out. Yet for any of us who have run downhill on
concrete, the more cushioned shoes seem to be less jarring. So how do we reconcile this?
I interviewed Benno Nigg, one of the foremost biomechanics gurus on running shoes, and
he was able to offer a new paradigm.
He started by telling me that there is no article in the literature which supports the notion
that peak force transmission will be altered with varied levels of cushioning. In fact peak
force transmission does not occur during heel contact as we might intuit, but in
midstance, where the internal forces on joints, muscles, and tendons are 4 to 5 times
greater than during impact.
There is something else that accounts for the perception that we are more comfortable in
a certain level of cushioning. Nigg's vibration model explains that when we impact the
ground, our soft tissue compartments (e.g., calf, hamstrings, etc.) start to vibrate. The
human body does not like vibrations. Consequently, muscles are activated to dampen
these vibrations. The degree of dampening that occurs in various types of shoes is what
leads to our perception of comfort in the shoe. So we have an innate sense of what works
for our bodies that is probably more accurate than any test could demonstrate for us. We
must also consider the fatigue that occurs within the muscles that are working to
distribute the vibrations. We know from other studies that fatigue can lead to injuries and
this may be part of the answer.
The trend in the shoe industry seems to be toward offering shoes with more minimalist
designs. Barefoot training can help train the small muscles that are not trained in stable
running shoes. Yet, it is hard to isolate all the force vectors because of the complex
arrangement of the joints of the lower extremity. And Robbins’ association between
injury and wearing shoes may be mitigated by other factors: perhaps in developing
countries barefoot runners may be too poor to seek medical attention; also, shod runners
may wear shoes because they have problems running barefoot.
Certainly runners that have grown up running barefoot in areas where it is more
prevalent, like Kenya, have been conditioned to run more efficiently barefoot than more
industrialized countries. Beyond that elite athletes are exceptional in their foot
musculature and would have an easier time in general running barefoot than others.
For more information on Dr. Pearl, visit http://docforjocks.blogspot.com.