1. Effects of Age on the Landing Techniques of Boys and Girls Ashley Swander Ashley Swander 1 Michael Pavol Michael Pavol 2 Dept. of Mechanical Engineering 1 Dept. of Mechanical Engineering Dept. of Nutrition & Exercise Sciences 2 Dept. of Nutrition & Exercise Sciences Oregon State University HHMI Summer 2006 http://biggirlinthemiddle.com/UAvOR05/index.html

2. Background Motivation: Increasing number of non- contact ACL injuries in female athletes Women 2-8 times more likely to suffer a serious knee injury than men Estimated 38,000 ACL injuries occur in female athletes in the U. S. annually http://www.orthone.com/sport/acl.asp

3. Background Women have different landing techniques than men Do girls and boys have similar landing techniques? When do techniques diverge? Ongoing 4-year study Dynamic Knee Abduction (From Hewett et al. 2006)

4. Purpose In Year One Data: Determine if there are differences in landing techniques between pre-pubescent boys and girls Hypothesis: Pre-pubescent boys and girls have similar landing techniques

5. Methods Subjects: Jumping Group 7 boys and 6 girls 7 mo. x 250/week drop landings off 24” box Control Group 17 boys and 8 girls 7-10 years old

6. Methods Static Trial Drop jump off 24” box Arms folded across chest Step off Land with one foot on each force plate 20 jumps

7. Data Collected Motion capture system Force plates

8. Data Analysis Variables: 3-D knee joint angles Resultant knee joint moments (i.e. torques) At touchdown Maximum value (touchdown end of landing)

9. Statistics 2-Factor analyses of variance Factors:Sex Jumping vs. Control Jumping vs. Control Covariate: Covariate:Age Performed for each angle and torque

10. Right Knee Angles and Moments + / –

11. Results Knee angles at touchdown *

12. Maximum Knee Angles * *

13. Maximum Knee Moments *

14. Conclusions Landing technique differs between boys and girls Sex-differences differ from those found in adults Girls knee abduction angle at touchdown knee abduction angle at touchdown maximum knee abduction angle maximum knee abduction angleBoys maximum knee adduction angle maximum knee adduction angle maximum knee extension moment maximum knee extension moment Both sexes have risk factors for ACL injury

15. Acknowledgements Howard Hughes Medical Institute Dr. Michael Pavol Dr. Kevin Ahern Funding:HHMIURISC Dr. Pavol College of Engineering http://deseretnews.com/dn/print/1,1442,635165805,00.html