New Data Support Experts` Opinion that Prostheses Do Not Enhance Top Running Speeds of Amputee Sprinters; Findings Published Today in Biology Letters

CAMBRIDGE, Mass.--(Business Wire)--
New data released by a team of experts provide further evidence that amputees
using running-specific prostheses have no overall biomechanical advantages when
running at top speeds compared to able-bodied sprinters. These findings were
published today in Biology Letters, a journal of the Royal Society of London.

The paper`s six authors are leading experts in the fields of biomechanics and
physiology, and include members of the research team whose previous findings
were presented to the Court of Arbitration for Sport (CAS) in Lausanne,
Switzerland in April 2008. Those previous findings were instrumental in
reversing the International Association of Athletics Federations` (IAAF) ban of
Oscar Pistorius, the South African bilateral amputee who attempted to qualify
for the 400-meter sprint at the Beijing Olympics. Pistorius runs using J-shaped,
high-performance Cheetah Flex-Foot prostheses.

In the new study, the researchers gathered biomechanical data from six elite,
unilateral amputee sprinters using running-specific prostheses. (Unilateral
sprinters have one lower-leg prosthesis and one biological leg.) Data were
analyzed from jogging speeds up to top sprinting speeds on a unique high-speed
instrumented treadmill at the Orthopedic Specialty Hospital in Salt Lake City,
Utah. The scientists compared the forces exerted on the ground and step timing
from the biological leg to the leg with the prosthesis. The results showed that
the primary determinant of top speed, the force applied to the ground, was 9
percent less in the leg with the prosthesis. They also found that the time
required for leg swing was not different between legs, and was similar to
non-amputee sprinters. The researchers therefore concluded that while a
running-specific prosthesis can partly emulate the spring-like behavior of a
biological leg, unilateral amputees cannot generate and apply as much force with
their prosthesis, thus impairing top speed.

"These new data support our previous findings that passive running-specific
prostheses are not able to provide the ground forces realized by biological
legs, and that we are not yet at a point in time when lower-limb prostheses
outperform biological limbs. But because the biomechanical and physiological
comparisons of amputee runners using prostheses to non-amputee runners are so
complex, we will continue conducting additional research to better understand
all the factors involved," says lead author Alena Grabowski, of the MIT Media
Lab`s Biomechatronics group.

"Our new data clearly show a ground-force deficiency caused by running-specific
prostheses," says Hugh Herr, senior author and head of the Biomechatronics
group. "Unilateral amputee sprinters simply cannot strike the ground as hard and
fast with their prosthetic leg as compared to their biological leg, a clear
disadvantage for achieving top sprinting speeds."

The other four authors are: Craig McGowan, University of Texas at Austin,
Neuromuscular Biomechanics Laboratory; William McDermott, The Orthopedic
Specialty Hospital; and Matthew Beale and Rodger Kram, University of Colorado at
Boulder Locomotion Laboratory. Grabowski, McGowan, Kram, and Herr were among the
seven experts whose work was presented at the CAS hearing last year.

The full Biology Letters paper, "Running-Specific Prostheses Limit Ground-Force
During Sprinting" can be read at the publication`s Web site:
http://rsbl.royalsocietypublishing.org/content/firstcite

MIT Media Lab
Alexandra Kahn, 617-253-0365
akahn@media.mit.edu

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