Preferential Quadriceps Activation in Female Athletes With Incremental Increases in Landing Intensity

in Journal of Applied Biomechanics
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The purpose of this study was to identify alterations in preparatory muscle activation patterns across different drop heights in female athletes. Sixteen female high school volleyball players performed the drop vertical jump from three different drop heights. Surface electromyography of the quadriceps and hamstrings were collected during the movement trials. As the drop height increased, muscle activation of the quadriceps during preparatory phase also increased (p < .05). However, the hamstrings activation showed no similar increases relative to drop height. Female athletes appear to preferentially rely on increased quadriceps activation, without an increase in hamstrings activation, with increased plyometric intensity. The resultant decreased activation ratio of the hamstrings relative to quadriceps before landing may represent altered dynamic knee stability and may contribute to the increased risk of ACL injury in female athletes.

Kevin R. Ford is with the Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children’s Hospital Medical Center, and with the Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH. Gregory D. Myer is with the Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH; the Departments of Pediatrics and Orthopaedic Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH; Athletic Training Division, School of Allied Medical Professions, Ohio State University, Columbus, OH; and with the Departments of Athletic Training, Sports Orthopaedics, and Pediatric Science Rocky Mountain University of Health Professions, Provo, UT. Laura C. Schmitt is with the Division of Physical Therapy, School of Allied Medical Professions, Ohio State University, Columbus, OH; and the Sports Medicine Biodynamics Center and Human Performance Laboratory and the Division of Occupational Therapy and Physical Therapy, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH. Timothy L. Uhl is with the Department of Rehabilitation Sciences and the Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY. Timothy E. Hewett is with the Sports Medicine Biodynamics Center and Human Performance Laboratory, Cincinnati Children’s Hospital Medical Center; the Department of Pediatrics, College of Medicine, University of Cincinnati; and the Departments of Orthopaedic Surgery and Biomedical Engineering, University of Cincinnati, Cincinnati, OH, and the Ohio State University Sports Medicine Sports Health and Performance Institute, Departments of Physiology and Cell Biology, and Orthopaedic Surgery, Columbus, OH; and the School of Allied Medical Professions and the College of Medicine, Family Medicine and Biomedical Engineering, Ohio State University, Columbus, OH.