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Document Title: Chappell-AJSM-Mar02.shtml
Article Title: A Comparison of Knee Kinetics between Male and Female Recreational Athletes in Stop-Jump Tasks
Authors: Jonathan D. Chappell, Bing Yu, PhD, Donald T. Kirkendall, PhD and William E. Garrett, MD, PhD
Publication: American Journal of Sports Medicine, Baltimore, Maryland
Date: March 2002
Volume 30, pages 261-267
Keywords: female athlete ACL injuries, biomechanics, kinematics, kinetics, stop-jump task, male-versus female, knee-injury prevention.
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Comments: This absolutely superb article is a must-read for all female athletes who have endured ACL injuries and for everyone who is interested in preventing such injuries. In this study, done in a biomechanics laboratory equipped with a three-dimensional video-camera system and floor-mounted force plates, the authors looked at the knee forces in athletes during rapid acceleration-deceleration activities associated with knee injuries. They found that during jump landing, females had a greater proximal anterior tibial shear force (i.e. the same type of anterior-drawer forcing as is used during the Lachmann and anterior drawer tests for ACL injuries). The authors also found that females, upong landing, also had greater knee extension and valgus moments (i.e. inwards torquing at the knee). The authors note that these findings show the females have different motor-control firmware setups than males, and that female-athlete knee-injury-prevention training should aim to reduce the proximal tibial anterior-shear forces at jump landing. Training for increased knee flexion and keeping the knees pointing somewhat outwards would also be helpful. Such training is already part of some training programs, most notably Cincinnati Sportsmetrics. Other good articles on these topics are Noyes-AJSM-Feb05.shtml, Ahmad-AJSM-Mar06.shtml, BarberWestin-AJSM-Mar06.shtml, and Mandelbaum-AJSM-Jul05.shtml.
ABSTRACT
We compared the knee kinetics of 10 male and 10 female recreational athletes (aged 19 to 25 years) performing forward, vertical, and backward stop-jump tasks. Three-dimensional videography and force plate data were used to record the subjects’ performance of the three stop-jump tasks, and an inverse dynamic procedure was used to estimate the knee joint resultant forces and moments. Women exhibited greater proximal anterior shear force than did men during the landing phase. All subjects exhibited greater proximal tibia anterior shear force during the landing phase of the backward stop-jump task than during the other two stop-jump tasks. Women also exhibited greater knee extension and valgus moments than did men during the landing phase of each stop-jump task. Men exhibited greater proximal tibia anterior shear force than did women during the takeoff phase of vertical and backward stop-jump tasks. These results indicate that female recreational athletes may have altered motor control strategies that result in knee positions in which anterior cruciate ligament injuries may occur. The landing phase was more stressful for the anterior cruciate ligament of both women and men than the takeoff phase in all stop-jump tasks. Technical training for female athletes may need to be focused on reducing the peak proximal tibia anterior shear force in stop-jump tasks. Further studies are needed to determine the factors associated with the increased peak proximal tibia anterior shear force in female recreational athletes.
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