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Insufficient Hamstring Strength Compromises Landing Technique in Adolescent Girls

WILD, CATHERINE Y.; STEELE, JULIE R.; MUNRO, BRIDGET J.

Medicine & Science in Sports & Exercise: March 2013 - Volume 45 - Issue 3 - p 497–505
doi: 10.1249/MSS.0b013e31827772f6
Applied Sciences

Purpose Women sustain more anterior cruciate ligament (ACL) ruptures than men, and this gender disparity is apparent from pubertal onset. Although the hamstring muscles play a vital role in ACL protection during landing by restraining anterior tibial motion relative to the femur, it is unknown whether hamstring strength affects landing biomechanics during a functional movement. This study aimed to determine whether pubescent girls with lower hamstring strength displayed different lower limb biomechanics when landing from a leap compared with girls with higher hamstring strength.

Methods Thirty-three healthy girls, age 10–13 yr, in Tanner stage II (pubertal onset) and 4–6 months from their peak height velocity were recruited. The concentric and the eccentric isokinetic strength of the hamstring and quadriceps muscles were assessed. On the basis of peak concentric hamstrings torque, participants were divided into a lower (peak torque < 45 N·m) and higher (peak torque > 60 N·m) strength group. Participants performed a functional landing movement, during which ground reaction forces (1000 Hz), lower limb electromyography (1000 Hz), and kinematic data (100 Hz) were collected.

Results Girls with lower hamstring strength displayed significantly (P < 0.05) greater knee abduction alignment, reduced hip abduction moments, and greater ACL loading at the time of the peak anteroposterior ground reaction forces compared with their stronger counterparts.

Conclusions Girls with reduced hamstring strength appear to have a decreased capacity to control lower limb frontal plane alignment. This reduced capacity appears to contribute to increased ACL loading and, in turn, increased potential for injury.

1Biomechanics Research Laboratory, School of Health Sciences, University of Wollongong, Wollongong, AUSTRALIA; and 2ARC Centre of Excellence in Electromaterials Science and Intelligent Polymer Research Institute, University of Wollongong, Wollongong, AUSTRALIA

Address for correspondence: Catherine Y. Wild, B.Sc. (Hons), Biomechanics Research Laboratory, University of Wollongong, Wollongong, Australia; E-mail: cw418@uowmail.edu.au.

Submitted for publication December 2011.

Accepted for publication October 2012.

© 2013 American College of Sports Medicine