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Life In The Fast Lane: The Mechanics Of Locomotion
Peter Weyand made 2008 Olympic headlines – and never set
foot in Beijing during the games.
Weyand, associate professor of applied physiology and biomechanics
in the Annette Caldwell Simmons School of Education
and Human Development, hosted an international team of experts
who conducted groundbreaking research on double amputee
Oscar Pistorius of South Africa. Some of their findings were released
for the first time in the Journal of Applied Physiology, published
in June.
Outfitted below the knee with j-shaped carbon fiber blades called
Cheetahs, the world-class sprinter became known as “Blade Runner.”
In 2008, the International Association of Athletics Federations
(IAAF) disqualified him from international competition against
able-bodied runners, which included the Olympics, because of
the prosthetics, claiming they provided a competitive advantage
and should be considered a technical aid.
Then director of Rice University’s Locomotion Laboratory,
Weyand and his collaborators put Pistorius through a series of
tests. It was an important research opportunity “because achieving
near-Olympic level running performance with artificial limbs
was so unprecedented that we had no idea whether the blades
were replicating the function of biological limbs or behaving in
some very different and advantageous manner,” Weyand says.
The team concluded that the IAAF’s specific claims of a competitive
advantage were scientifically unfounded, and the Court
of Arbitration for Sport determined that Pistorius could compete.
The recently published paper expounds on the differences
between natural limbs and prosthetics: Pistorius’ physiology –
energy cost and fatigability – is similar to that of intact-limb athletes,
but his sprint-running mechanics are markedly dissimilar.
“Legs must perform different functions
during the stance and swing
phases of the stride, as well as
during the start, acceleration
and relatively constant-speed
phases of sprint running. Collectively,
the results underscore
the difficulty of providing
these multiple mechanical
functions with
a single, relatively simple
prosthetic design.”
Although he didn’t
make the final cut for
South Africa’s team, Pistorius cleared a historic hurdle – thanks to Weyand and others
who took the case pro bono.
Weyand, himself a 15-year track and field competitor, earned a
Ph.D. in exercise physiology from the University of Georgia in 1992.
He subsequently directed research efforts at Harvard University’s
Concord Field Station, a large-animal facility specializing in terrestrial
locomotion research, before joining Rice in 2003.
Lured by the challenge of helping to chart the direction of SMU’s
Department of Applied Physiology and Wellness, Weyand arrived
at the University last August.
He is helping develop a new undergraduate
major in applied physiology and sports management and
a graduate program in applied physiology.
This summer he is setting up a lab where he’ll continue to examine
the relationships between muscle function, metabolic energy
expenditure and human physiology.
Weyand and colleagues have noted that large animals enjoy
better locomotor economy – the thriftiness of energy output for a
given physical task – on a per pound basis than small animals. “A
mouse expends 30 times more energy than an elephant in proportion
to their weight,” he says. “The trend is the same for people:
Large people have better locomotor economy on a per pound basis
than small people or kids.”
His investigations into the links between the whole-body mechanics
of movement and metabolic energy expenditure using
the “mouse to elephant” approach have a variety of applications.
Among them are emerging sensor technologies, new methods for
field estimates of energy expenditure and more sophisticated
techniques for assessing physical and metabolic fitness in humans.
He holds a patent on a performance prediction method using
foot signals and heart rate to forecast a person’s aerobic fitness,
and was instrumental in developing technology incorporated into
the Nike + iPod Sport Kit, which uses a sport-shoe sensor to calculate
distance, pace and calories burned.
Weyand’s studies are relevant to elite athletes, weekend warriors
and even soldiers in training. “After testing many different animals,
we figured out that we could make very accurate predictions about
the metabolic energy expense of walking by using body weight and
the amount of time the foot is in contact with the ground,” he says.
With research funded by the U.S. Army Medical Research and
Materiel Command, Weyand hopes to apply those prediction
methods in shoe-mounted sensors that will assess and monitor
soldiers’ physical fitness in the field and bring improved assessment
techniques to the general population as well.
For more information:
smu.edu/peterweyand
