effects of age on the landing techniques of boys and girls ashley swander ashley swander 1 michael...
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Effects of Age on the Effects of Age on the Landing Techniques of Landing Techniques of
Boys and GirlsBoys and Girls Ashley SwanderAshley Swander1
Michael PavolMichael Pavol2
1Dept. of Mechanical Dept. of Mechanical EngineeringEngineering
2Dept. of Nutrition & Exercise Dept. of Nutrition & Exercise SciencesSciences
Oregon State University Oregon State University
HHMI Summer 2006HHMI Summer 2006
http://biggirlinthemiddle.com/UAvOR05/index.html
BackgroundBackgroundMotivation:Motivation:
Increasing number of Increasing number of non-contact ACL non-contact ACL injuries in female injuries in female athletesathletes
Women 2-8 times Women 2-8 times more likely to suffer a more likely to suffer a serious knee injury serious knee injury than men than men
Estimated 38,000 ACL Estimated 38,000 ACL injuries occur in injuries occur in female athletes in the female athletes in the U. S. annuallyU. S. annually
http://www.orthone.com/sport/acl.asphttp://www.orthone.com/sport/acl.asp
BackgroundBackground
Women have Women have different landing different landing techniques than mentechniques than men
Do girls and boys Do girls and boys have similar landing have similar landing techniques?techniques?
When do techniques When do techniques diverge?diverge?
Ongoing 4-year Ongoing 4-year studystudy
Dynamic Knee Abduction(From Hewett et al. 2006)
PurposePurpose
In Year One Data:In Year One Data:Determine if there are differences in Determine if there are differences in landing techniques between pre-landing techniques between pre-pubescent boys and girlspubescent boys and girls
Hypothesis: Hypothesis: Pre-pubescent boys and girls have Pre-pubescent boys and girls have similar landing techniquessimilar landing techniques
MethodsMethods
Subjects:Subjects:
Jumping Group Jumping Group
7 boys and 6 girls7 boys and 6 girls
7 mo. x 250/week drop landings off 24” box7 mo. x 250/week drop landings off 24” box
Control GroupControl Group
17 boys and 8 girls17 boys and 8 girls
7-10 years old7-10 years old
MethodsMethods
Static TrialStatic Trial
Drop jump off 24” Drop jump off 24” boxbox
Arms folded across Arms folded across chestchest
Step offStep off
Land with one foot Land with one foot on each force plateon each force plate
20 jumps 20 jumps
Data AnalysisData Analysis
Variables:Variables:
3-D knee joint angles3-D knee joint angles
Resultant knee joint moments (i.e. Resultant knee joint moments (i.e.
torques)torques)
At touchdownAt touchdown
Maximum value (touchdown end Maximum value (touchdown end
of landing)of landing)
StatisticsStatistics
2-Factor analyses of variance2-Factor analyses of variance
Factors: Factors:
SexSex
Jumping vs. ControlJumping vs. Control
Covariate:Covariate:
AgeAge
Performed for each angle and torquePerformed for each angle and torque
ResultsResultsKnee angles at touchdownKnee angles at touchdown
-5
0
5
10
15
20
25
Flexion Abduction Internal Rotation
An
gle
(d
eg
ree
s)
Boys Girls
*
Maximum Knee AnglesMaximum Knee Angles
0
10
20
30
40
50
60
70
80
90
100
Flexion
An
gle
(d
egre
es)
0
2
4
6
8
10
12
14
16
Abduction Adduction
An
gle
(d
egre
es)
Boys Girls
*
*
ConclusionsConclusionsLanding technique differs between boys Landing technique differs between boys and girlsand girls
Sex-differences differ from those found in Sex-differences differ from those found in adultsadults
GirlsGirls knee abduction angle at touchdownknee abduction angle at touchdown
maximum knee abduction anglemaximum knee abduction angle
BoysBoys maximum knee adduction anglemaximum knee adduction angle
maximum knee extension momentmaximum knee extension moment
Both sexes have risk factors for ACL injuryBoth sexes have risk factors for ACL injury
AcknowledgementsAcknowledgements
Howard Hughes Medical InstituteHoward Hughes Medical Institute
Dr. Michael PavolDr. Michael Pavol
Dr. Kevin AhernDr. Kevin Ahern
Funding:Funding:HHMIHHMI
URISCURISC
Dr. PavolDr. Pavol
College of EngineeringCollege of Engineeringhttp://deseretnews.com/dn/print/1,1442,635165805,00.html
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