Biomechanical and Performance Differences Between Female Soccer Athletes in National Collegiate Athletic Association Divisions I and III
Rose Smith, PT*; Kevin R. Ford, MS†; Gregory D. Myer, MS†; Adam Holleran, PT*; Erin Treadway, PT*; Timothy E. Hewett, PhD*†*University of Cincinnati, Cincinnati, OH; †Cincinnati Children’s Hospital Medical Center and Research Foundation, Cincinnati, OH
Context: The recent increase in women’s varsity soccer participation has been accompanied by a lower extremity injury rate that is 2 to 6 times that of their male counterparts. Objective: To deﬁne the differences between lower extremity biomechanics (knee abductionand knee ﬂexion measures) and performance (maximal vertical jump height) between National Collegiate Athletic Association Division I and III female soccer athletes during a drop vertical jump. Design: Mixed 2 2 design. Setting: Research laboratory. Patients or Other Participants: Thirty-four female collegiate soccer players (Division I: n 19; Division III: n 15) participated in the study. The groupswere similar in height and mass. Intervention(s): Each subject performed a maximal vertical jump, followed by 3 drop vertical jumps. Main Outcome Measure(s): Kinematics (knee abduction and ﬂexion angles) and kinetics (knee abduction and ﬂexion moments) were measured with a motion analysis system and 2 force platforms during the drop vertical jumps. Results: Knee abduction angular range of motionand knee abduction external moments were not different between groups (P .05). However, Division I athletes demonstrated decreased knee ﬂexion range of motion (P .038) and greater peak external knee ﬂexion moment (P .009) compared with Division III athletes. Division I athletes demonstrated increased vertical jump height compared with Division III (P .008). Conclusions: Division I athletesdemonstrated different sagittal-plane mechanics than Division III athletes, which may facilitate improved performance. The similarities in anterior cruciate ligament injury risk factors (knee abduction torques and angles) may correlate with the consistent incidence of anterior cruciate ligament injury across divisions. Key Words: knee valgus, knee ﬂexion angle, lower extremity, women’s soccer
KeyPoints • Compared with Division III female soccer athletes, Division I female soccer athletes landed from a vertical drop with a decreased knee ﬂexion angle and increased vertical jump height. • The observed similarities in coronal-plane knee abduction range of motion and moments between Divisions I and III female soccer athletes may be related to the consistent incidence of anterior cruciate ligamentinjuries across divisions. • Injury-prevention programs designed to decrease the abduction angle at the knee during landing may be recommended for female soccer players at all levels.
olleges and universities have expanded female athletic programs since the inception of Title IX of the Educational Assistance Act (1972). Women’s varsity soccer programs have grown 48% over the 5-year period from1992– 1993 to 1998–1999.1 This increase in participation has been accompanied by lower extremity injury rates that are twice as high in female soccer players as in their male counterparts.2,3 The knee is one of the most frequently injured body parts for female soccer players, with major knee injuries accounting for 42% of injuries resulting in more than 30 days of time loss.4 The anteriorcruciate ligament (ACL) accounted for more than half of those injuries during one soccer season.4 The collegiate athlete falls into the 15-year through 25-year age range for female athletes, which has the highest incidence of ACL injuries in landing and pivoting sports, with as many as 70% of these injuries being noncontact.5,6 Female college athletes are at a 2-fold to 6-fold greater risk