Purpose: The purpose of this study was to compare kicking biomechanics between young female soccer players at two different stages of physical maturation and to identify biomechanical predictors of peak foot velocity.
Methods: Swing and stance limb kinematics and kinetics were recorded from 20 female soccer players (10 prepubertal, 10 postpubertal) while kicking a soccer ball using an angled two-step approach. Peak foot velocity as well as hip and knee kinematics and kinetics were compared between groups using independent-samples t-tests. Pearson correlation coefficients and stepwise multiple regression were used to identify predictors of peak foot velocity.
Results: Peak foot velocity and the peak swing limb net hip flexor moment was significantly greater in the postpubertal group when compared with the prepubertal group (13.4 vs 11.6 m·s−1, P = 0.003; 1.22 vs 1.07 N·m·kg−1·m−1, P = 0.03). Peak stance limb hip and knee extensor moments were not different between groups. Although the peak swing limb hip and knee flexion angles were similar between groups, the postpubertal group demonstrated significantly less peak stance limb hip and knee flexion angles when compared with the prepubertal group (P < 0.001 and P = 0.045). Using a linear regression model, swing limb peak hip flexor moment and peak swing limb hip extension range of motion combined to explain 65% of the variance in peak foot velocity.
Conclusions: Despite a difference in stance limb kinematics, similar swing limb kinematics between groups indicates that the prepubertal female athletes kicked with a mature swing limb kick pattern. The ability to generate a large hip flexor moment of the swing limb seems to be an important factor for improving kicking performance in young female soccer players.
1Jacquelin Perry Musculoskeletal Biomechanics Research Laboratory, Division of Biokinesiology and Physical Therapy, School of Dentistry, University of Southern California, Los Angeles, CA; and 2Department of Physical Therapy, California State University Long Beach, Long Beach, CA
Address for correspondence: Christopher M. Powers, P.T., Ph.D., Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar St., CHP-155, Los Angeles, CA 90089-9006; E-mail: firstname.lastname@example.org.
Submitted for publication December 2010.
Accepted for publication March 2011.