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Kinematics and Electromyography of Landing Preparation in Vertical Stop-Jump

Risks for Noncontact Anterior Cruciate Ligament Injury

Jonathan D. Chappell, MD^*, R. Alexander Creighton, MD^*, Carol Giuliani, PhD, Bing Yu, PhD^*,,, and William E. Garrett, MD, PhD^,||

From the ^* Department of Orthopaedic Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina, Center for Human Movement Science, Division of Physical Therapy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, and ^|| Division of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina

Address correspondence to Bing Yu, PhD, Division of Physical Therapy, CB #7135 Medical School Wing E, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7135 (e-mail: byu{at}med.unc.edu).

Background: Biomechanical analysis of stop-jump tasks has demonstrated gender differences during landing and a potential increase in risk of noncontact anterior cruciate ligament injury for female athletes. Analysis of landing preparation could advance our understanding of neuromuscular control in movement patterns and be applied to the development of prevention strategies for noncontact anterior cruciate ligament injury.

Hypothesis: There are differences in the lower extremity joint angles and electromyography of male and female recreational athletes during the landing preparation of a stop-jump task.

Study Design: Controlled laboratory study.

Methods: Three-dimensional videographic and electromyographic data were collected for 36 recreational athletes (17 men and 19 women) performing vertical stop-jump tasks. Knee and hip angular motion patterns were determined during the flight phase before landing.

Results: Knee and hip motion patterns and quadriceps and hamstring activation patterns exhibited significant gender differences. Female subjects generally exhibited decreased knee flexion (P = .001), hip flexion (P = .001), hip abduction (P = .001), and hip external rotation (P = .03); increased knee internal rotation (P = .001); and increased quadriceps activation (P = .001) compared with male subjects. Female subjects also exhibited increased hamstring activation before landing but a trend of decreased hamstring activation after landing compared with male subjects (P = .001).

Conclusion: Lower extremity motion patterns during landing of the stop-jump task are preprogrammed before landing. Female subjects prepared for landing with decreased hip and knee flexion at landing, increased quadriceps activation, and decreased hamstring activation, which may result in increased anterior cruciate ligament loading during the landing of the stop-jump task and the risk for noncontact ACL injury.

Key Words: anterior cruciate ligament (ACL) injury • risk factors • landing • biomechanics • motor control

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				P Renstrom, A Ljungqvist, E Arendt, B Beynnon, T Fukubayashi, W Garrett, T Georgoulis, T E Hewett, R Johnson, T Krosshaug, et al. Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement Br. J. Sports Med., June 1, 2008; 42(6): 394 - 412. [Abstract] [Full Text] [PDF]