Measurement of accelerations experienced by rodeo riders
Watkins S, Jennings R, Knox T, Andrews D, Plaga J, Ivan C
AGENDA
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Rodeo events and recent statistics
Sports-related head injury
Accelerometers 101
Details of the 2007 pilot study
Rodeo footage and results
Background on Rodeo Events:
Bareback Riding
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Rules for the Rider
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Disqualification
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Properly “mark out” the horse on its first
jump out of the chute
Maintain a one-hand hold on the rigging
throughout the eight-second ride
Spurring is required
Contacting the equipment, the animal, or
the rider with the his free hand
Failure to “mark out”
Basis for Scoring
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Rider’s control and style
Rider’s spurring technique
Horse’s bucking efforts
http://www.washburncounty.com/rodeo/garretta.gif
Background on Rodeo Events:
Bull Riding
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Rules for the Rider
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Disqualification
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Maintain a one-hand hold throughout
the eight-second ride
Attempt to remain forward, or "over his
hand," at all times
Spurring not required
Contacting the equipment, the animal,
or the rider with the his free hand
Basis for Scoring
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Rider’s control and style
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http://www.shrinerodeo.com/images/bull-riding.jpg
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Good body position
Use of the free arm
Spurring action
Efforts of the bull
Recent Injury Statistics
The Justin Sportsmedicine Team (JSMT) has over twenty-five years of experience with rodeo
injuries and covers approximately twenty percent of PRCA sanctioned rodeo performances
annually. A recent report released by JSMT examined injury data collected from 1981 to 2005.
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Bareback Riding
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Events produce second
largest number of injuries
Accounts for 20% of
competition injuries
Most common sites of injury
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Head
Shoulder
Knee
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Bull Riding
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Injuries are most common
during this event
Accounts for 50% of
competition injuries
Most common sites of injury
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Head
Face
Shoulder
What do we know about head injury ?
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U.S. Statistics
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250,000 - 300,000 sports-related head injuries
occur annually
Annual costs exceed 1 billion dollars
Rodeo Statistics
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Most common sites of injury are the head and face
(16% of injuries)
Most common major injury is concussion
(>50% of all major injuries)
Guskiewicz KM, McCrea M, Marshall SW, et al. Cumulative effects of recurrent concussion in collegiate football players: the NCAA Concussion Study. JAMA 2003;290:2549–55.
Guskiewicz KM, Weaver NL, Padua DA, et al. Epidemiology of concussion in collegiate and high school football players. Am J Sports Med 2000;28:643–50.
Iverson GL, Gaetz M, Lovell MR, et al. Cumulative effects of concussion in amateur athletes. Brain Injury 2004;18:433–43.
More on concussion
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Pathophysiology remains a mystery
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Historical definition
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associated with structural changes? (as with severe TBI)
reversible functional changes?
Transient disturbance of neurological function caused by “shaking”
of the brain that accompanies low velocity brain injuries
Congress of Neurological Surgeons “consensus” definition
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A clinical syndrome characterized by the immediate and transient
post-traumatic impairment of neural function such as alteration of
consciousness, disturbance of vision or equilibrium due to
mechanical forces
Why do we care about concussion?
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Sports concussion
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>90% are mild (no loss of consciousness)
Carries a high risk of recurrent concussion
(athlete often allowed to compete before recovery
from the initial injury)
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Repeat incidents
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Generally more serious
Slower to resolve
May result in long-term dysfunction
No certainty concerning safe to return to
competition
http://apps.uwhealth.org/health/adam/graphics/images/en/17143.jpg
How is concussion
associated with acceleration?
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“Acceleration concussion” has been proposed
as a general term that can be applied to all
forms of traumatic brain injury
Accelerations in the 150–200 g range are
known to cause head injury
Little is known about repeated exposure to
moderate accelerations
Olvey S, Knox T, Cohn K. The development of a method to measure head acceleration and motion in high-impact crashes. Neurosurgery 54: 672-677, 2004.
Measuring Acceleration
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Accelerometers
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Many types: some simple,
some complex
Basic components
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A moveable mass
A way to determine how much
the mass has moved
Can measure linear and
angular accelerations in
multiple axes
How they work
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When no forces are present
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The mass does not move
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Mechanical: Spring is not stretched
Electrical: The voltage is equal at all plates
When forces are present
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The mass is displaced
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Mechanical: The spring is stretched
Electrical: The voltage at the nearer plates increases
The Physics
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Force acting on the mass is calculated by the
distance the mass has moved and the inherent
properties of the system
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Measured displacement & stiffness (k) of the spring
or
Change in voltage & current applied to the circuit
F=ma is used to calculate the acceleration
With a mass that shifts up and down, left and right, and back
and forth, movement can be measured in three dimensions.
The ear-mounted,
tri-axial accelerometer
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Designed by Olvey, Knox et al
Impetus for design
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In crash situations, driver’s custom fitted
ear-mounted communications devices
remained seated in the ear canal
Small, tri-axial accelerometers could be
embedded within the earpiece to allow
for head-centered measurements of
acceleration
Initially used to examine head
accelerations in race car drivers
Olvey S, Knox T, Cohn K. The development of a method
to measure head acceleration and motion in high-impact
crashes. Neurosurgery 54: 672-677, 2004.
Goals of the study
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To demonstrate the ability to obtain precise
measurements of the accelerations experienced by
professional rough stock riders during rodeo events
To use the knowledge gained toward the design of the
first large scale study of the accelerations encountered
during such events
To use the acceleration data gained to better understand
the pathomechanics of head injury and assist in the
creation of injury prevention techniques
Preparatory Steps
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UTMB IRB approval obtained
Subjects selected
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Two male professional rough stock riders
Recruited at rodeo events preceding the
Houston Livestock Show and Rodeo
Informed consent obtained
Custom mold of the ear canals made
Accelerometer systems inserted into
each mold
Houston Livestock Show and Rodeo
March 6, 2007
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Minutes prior to the competition event
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On entering the chute
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Each subject was assisted in inserting his earpiece
Small wires connecting the earpieces to the recording device
were secured to the rider’s clothing
Data recorder was placed into a padded belt and fastened
around the rider’s waist
Data recorder was activated
Rider participated in his scheduled event as usual
After the event
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Data recorder was collected
Information transferred to computer for further analysis
Houston Livestock Show and Rodeo
March 6, 2007
A sample of the data
00HEADLE00H3ACXP (g)
50
40
30
20
10
0
-10
-20
-30
82
87
92
Time (Seconds)
97
102
Results
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Bareback Rider
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8 seconds of ride completed
No report of injury
Resultant maximum acceleration: 46 g’s!
Bull Rider
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Failed to complete ride
No report of injury
Resultant maximum acceleration: 26 g’s
Conclusions
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Human data on acceleration forces in rodeo
events are lacking
Although it is understood that sports-related
concussions are common and dangerous to
riders, little is known about pathomechanics
Further studies on the effects of frequent
exposure to accelerations (<50g) are
needed for better risk assessment
What’s Next
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Large scale study at the 2008 Houston Rodeo
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8 bareback riders
8 bull riders
Aerobatic acceleration study
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Details TBD
Acknowledgements
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J. Pat Evans Research Foundation
for the funding provided to support this research
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Justin Sportsmedicine Team
Houston Livestock Show and Rodeo
Professional Rodeo Cowboys Association
United States Air Force Research Laboratory