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EMBARGOED
UNTIL 12:01 AM EST
Thursday,
September 25, 2008
Contact: Donna Krupa
Office: (301) 634-7209
Newsroom Phone: 843-681-0794 or 95
Cell: 703-967-2751
dkrupa@the-aps.org
Galloping And Breathing At
High Speed:
Equine research into movement and breathing may
translate into help for other horses and humans
HILTON HEAD, SC–The
coordination of two systems are key for any horse to walk, trot, gallop or
win a race. The first are the lower limbs, which allow the animal to move
along on a “spring-like” tendon. The second is a complicated respiratory
system, which allows a horse to take in one breadth for every stride they
make while racing. For more than a decade a team of researchers has been
working to unlock the secrets of equines. Their findings may provide a
springboard for better muscular horse health, and a different approach to
breathing devices for humans.
John Hermanson, Norm Ducharme and Jonathan Cheetham,
all of the Cornell University College of Veterinary Medicine, Ithaca, NY,
John Bertram, University of Calgary, College of Medicine, Calgary, Alberta,
CN, and Michael Butcher, Department of Biological Sciences, Youngstown State
University, Youngstown, OH, comprise the research team. Dr. Hermanson will
discuss the group’s work at the American Physiological Society’s (APS) (www.The-APS.org)
meeting, The Integrative Biology of Exercise V. The conference
is being held September 24-27, 2008 in Hilton Head, SC.
Equine Movement
The lower limbs (legs) of horses are what allow them to
move, either by walking, trotting, galloping or jumping. An elastic storage
area is located inside the forelimbs, made up of long tendons. These
tendons are vulnerable to injury during high speed training or racing.
The researchers focused their efforts on understanding
why this occurs. They found that two principal muscular factors in the fore
limb guide a horse’s forward movement. The first is the springy
“pogo-stick” quality of the superficial digital flexor tendon, which
provides the “bouncing” effect, which allows for trotting and, to a lesser
extent, galloping. The second is work generated by the parallel deep digital
flexor, which moves the horse forward over the ground. It is the balance
between these two muscles that is required for horses to be able to move.
Out of these discoveries have come the potential for
veterinary applications. Among them is the possibility that some of the
breakdown in the forelimbs may be related to fatigue within the deep digital
flexor resulting from stress and strain on the tendons of the animal.
According to Dr. Hermanson, “Fatigue of the deep flexor
muscle may overload the superficial digital flexor muscle and tendon,
especially towards the end of intense, high-speed exercise.
The Importance of
Respiration
When a horse is running, its breathing and stride are
linked in a 1:1 ratio, so for every stride they take, they also take one
breath. The peak airflow they generate is very high (about 80 liters per
second). Thus, a very small defect in the airway can cause a big decrease in
performance. Two cartilages (the arytenoids cartilages) protect the larynx
during swallowing. When the horse swallows, these cartilages close; when the
horse breathes, the cartridges open. When the horse exercises, they open to
the maximum extent possible in order to as much airflow as possible to reach
the lungs.
These cartilages are opened by a muscle that is
innervated by a long nerve, the recurrent laryngeal nerve, which runs from
the brain, down the neck, and around the base of the aorta. This nerve is
susceptible to disease and damage. When that occurs, the muscle does not
function properly, so it is unable to properly open the cartilage. As a
result, the cartilages collapse, obstruct the airflow and lead to a poor
performance from the horse.
An Airway Solution for
Horses … and People?
For the last three years the researchers have been
developing a pacemaker for the larynx. The electrical implant can be placed
into the muscle or around the nerve in order to stimulate the muscle and
keep it open during exercise. The implant has been developed to the point
where it can be used to keep the airways of horses running 35-40 miles per
hour, fully open.
The researchers are part of a team looking at
application for the pacemaker for humans for individuals who have laryngeal
paralysis or undergo laryngeal transplant. The disorder can be a
complication of thyroid surgery in people who have had thyroidectomies,
usually to remove cancer from the thyroid gland. In addition to the
paralysis, it can effect speech, voice and swallowing. According to Dr.
Cheetham, "We are hopeful that this pacemaker, tried in horses, will
eventually be helpful to humans.”
Conclusion
According to Dr. Hermanson, “Horses are uniquely
designed athletes that are exceptionally useful for the study of limbs,
respiration and other systems of the body. This type of translational
research benefits all concerned.”
******
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS;
www.The-APS.org/press) has been an integral
part of this discovery process since it was established in 1887.
# # #
NOTE TO EDITORS: The APS Conference, The Integrative Biology of
Exercise V, is being held September 24-27, 2008 in Hilton Head, SC.
Members of the media are invited to attend. To register, or to schedule an
interview with Dr. Hermanson or Dr. Cheetham, please contact Donna
Krupa at 301.634.7209 (office), 703.967.2751 (cell) or
DKrupa@the-APS.org. There will be an APS newsroom onsite.
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