Many of today's running shoes feature a heavy cushioned
heel. New research presented at the 2013 Annual Meeting of the American Academy
of Orthopaedic Surgeons (AAOS) found that these shoes may alter an adolescent
runner's biomechanics (the forces exerted by muscles and gravity on the
skeletal structure) and diminish performance.
Researchers recruited 12 adolescent competitive athletes
from local track teams, and asked them to run on a treadmill in large heel
trainers, track flats and without any shoes (barefoot) at four different
speeds. Biomechanics – stride length, heel height during posterior swing phase
and foot/ground contact – were measured with a motion capture system.
"Running barefoot or running in less of a running shoe
(toe shoes, for example) is a newer trend," said Scott Mullen, MD, an
orthopaedic surgeon at The University of Kansas Hospital. "What we were
trying to evaluate is whether or not the foot strike would change in an
adolescent – who doesn't yet have a permanently established gate – when they
changed their shoe or running speed."
What the study showed
The researchers found that shoe type "dramatically"
altered running biomechanics in the adolescent runners. When wearing cushioned
heel trainers, the athletes landed on their heel 69.8% of the time at all
speeds. With the track flats, the heel was the first point of contact less than
35% of the time; and when barefoot, less than 30% of the time.
Shoes with cushioned heels promote a heel-strike running
pattern, whereas runners with track flats and barefoot had a forefoot or
mid-foot strike pattern.
"What we found is that simply by changing their
footwear, the runners' foot strike would change," said Dr Mullen.
"When they ran in the cushioned heel or an average running shoe - even when
running a 5-minute mile - the athletes landed on their heel first."
Many adolescent runners train in cushioned heels and compete
in track spikes, "which may give them less of a (performance)
advantage" in competition, said Dr. Mullen.
As a 2010 study found that heel strike running distributes
more energy to hips and knees, running in flat- soled shoes that promote a
forefoot strike may "present a healthier foot strike for runners over a
lifetime, possibly resulting in fewer hip and knee problems," said Dr.
Mullen. More research is needed to determine the effects of shoes on foot