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A SHOE FOR EVERY FOOT!
By Kirk M. Herring, D.P.M.
F.A.C.F.A.O.M.
Imagine peeking into a runners closet!
Will you find an orderly array of training shoes and racing
flats or a heap of old favorites, discarded relics and mismatched
choices. With so many companies and shoes to choose from
our choices couldn’t be better or more difficult.
When shopping for a new racing
or training shoe what do you look at first? The price, the color,
the shape, the cushioning, the outsole, the lug pattern, the
size, the brand, your doctor’s list, or its weight. Yes,
all of these may represent important factors leading to the successful
selection of your next running shoe but didn’t you forget
one very important factor, your foot. The running shoe is an
extension of our foot, a mismatch can lead to the development
of a wide array of over use injuries or uncomfortable maladies.
The running shoe serves as a structural
and functional extension of our foot. Chosen wisely it can
impose a beneficial influence on our running, improperly
chosen the shoe can amplify anatomical and functional flaws
and there by increase the risk of overuse injuries. To better
understand the role our running shoes play we must first
examine the basic shape and movement characteristics of
the foot in motion. Several methods have been devised to
examine or categorize the anatomical shape of the foot;
the most widely applied method subdivides feet by the height
of the arch, including, high arched, normal arched and low
and flat arched feet. Classifying the motion of the foot
during running is more difficult. Again several systems
have been devised, the most widely applied relies upon the
angular relationship of the heel to the supporting surface
during the mid stance phase of running gait. This classification
system creates four categories which include, under pronation,
neutral, over pronation and severe over pronation. The combination
of these two basic factors can assist you in your search
for a new running shoe. (see
table 1).
The anatomy of the foot is well
suited to motion, it is more poorly suited to static upright
stance. The foot clearly serves as a primary shock absorber at
heel contact. The robust heel with a highly developed plantar
fat pad and spongeous internal structure can absorb a significant
portion of the forces imposed upon the supporting extremity at
heel contact. Shock absorption is further enhanced by the internal
motion of the heel during initial heel contact. This internal
motion is referred to as pronation, and results in a flexible
and pronated foot. The remaining forces of impact are absorbed
by other bones, joints, and soft tissues of the supporting extremity
and torso. At the end of heel contact, the forces of running
are shifted to the ball-of-the-foot. The foot now begins a lengthy
process of reversing the flexible and pronated position of the
foot to that of a structure with internal rigidity and stability.
This reversal is referred to as supination. The supinating foot
is more effective at converting the efforts of the large calf
and hamstring muscles into forward motion. Supination of the
foot begins during midstance and continues until the foot contacts
the ground again at heel contact. Thus, the events of pronation
and supination are necessary for normal running gait.
As previously described, we will
describe the shape of the foot by the nature of the arch, its
height is not easily determined by casual observations. To best
visualize the characteristic shape of your arch, moisten the
sole of the foot with water and stand on a sheet of paper. The
outline or imprint will generally depict the pattern of weight
bearing and there by the basic height of your arch. The higher
your arch the less contact your foot will have with the ground
alternately, the more contact your foot has with the ground the
lower the arch. This information is important as the field of
available running shoes can be initially narrowed by shoe shape
or last.
Variations to the pattern of
normal running gait frequently occur. They can range from minor
flaws to severe periods of lower extremity instability. Irregular
terrain, canted roads, abnormal anatomy, neuromuscular and connective
tissue disorders, improper running shoes, worn out running shoes
and poorly fit orthotics can all alter the characteristics of
your running gait. Like wise, improvements to an abnormal gait
pattern can be achieved by careful shoe selection, well fit orthotics
and careful attention to training. The characteristics of normal
and abnormal gait can be best observed on video gait analysis.
Identifying your pattern of running gait or function represents
the second factor critical to the selection of an appropriate
running shoe.
Previously, four categories of
foot function were introduced, including under pronation, neutral,
over pronation and severe over pronation. These categories have
been widely discussed in running circles. Under pronation represents
the inability of the heel to achieve an everted (or pronated)
position during heel contact or during the opening period of
midstance in running gait. This foot appears to remain supinated
through out the stance phase of the running gait. Shoes often
wear rapidly along the outer (lateral) aspect of the shoe, with
little or no wear along the inner (medial) aspect of the shoe.
The heel counter and midsole are frequently broken down laterally
and the heel counter will remain in an inverted (supinated) position.
Neutral foot function is common; the heel everts (pronates) during
heel contact and into the midstance phase of running gait. The
neutral foot will reverse this motion by inversion (supination)
of the foot during midstance and heel off phases of running gait.
Shoes wear at the outer (lateral) heel, center near the ball-of-the-foot
and in line with the big toe. Over pronation occurs when the
heel everts (pronates) during heel contact and continues to progress
well beyond the midpoint of the midstance phase of gait. For
this foot resupination of the foot does occur but not until the
very end of the midstance phase of gait or as heel off begins.
Shoe wear patterns demonstrate increased outsole wear at the
outer (lateral) heel, inner (medial) side of the ball-of-the-foot
and on the inner (medial) side of the big toe. Severe over pronation
is rare, but when present will result in rapid evertion (pronation)
of the heel at heel contact. The heel will remain visibly everted
(pronated) throughout the stance phase of gait. This foot will
resupinate only during the swing phase of running gait as the
trailing leg is brought forward in preparation for the next stance
phase. Wear patterns to the shoes of severe over pronators demonstrate
accelerated outer (lateral) heel wear, increased medial only
wear at the ball-of-the-foot and medial to the big toe. Heel
counters and midsole are usually crushed over medially and left
in an everted (pronated) position.
Prolonged pronation and premature
initiation of supination are associated with overuse injuries.
Recognizing which pattern best depicts your foot will provide
you and the shoe store staff with another critical piece
to fit in the running shoe puzzle. In general, when selecting
a new shoe start with a last that best conforms to your
foot. High arched feet generally respond best to curved
and split lasted shoes. Normal arched feet will do fine
in semi curved or semi straight and split or combination
lasted shoes. The flat or low arched foot will do best in
a semi straight or semi curved or straight and a combination
or board last shoe. These trends are meant to represent
a starting point, to further narrow down the field of running
shoe choices introduce the characteristics of your running
gait (see
table 1).
By following these guidelines
and following the suggestions in table 1 you have a good chance
of choosing a good running shoe for yourself. Your running shoe
salesperson can be instrumental as they help you pick a couple
of shoes to compare. Happy shopping and running!©
Dr. Kirk Herring can be reached
at Inland Northwest Family Foot Care and The Running Sports Injury
Center at (509) 926-1559.
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