The effects of gender and ACL reconstruction on lower extremity coupling variability during performance of randomly cued cutting techniques.

Recently, it has been suggested that movement variability –particularly coordination variability – can be functional in reducing the risk of injury. Pollard et al. (2005: Journal of Applied Biomechanics, 21, 143 – 152) reported that females demonstrate lower coordination variability than males during performance of an unanticipated cutting movement. Furthermore, a history of lower extremity injury has been shown to effect lower extremity coordination variability during running (Heiderscheit et al., 2002: Journal of Applied Biomechanics, 18, 110 – 121). Therefore, the purpose of this study was to evaluate both the effect of gender and history of ACL injury on lower extremity joint coupling variability during performance of an unanticipated cutting technique. With approval from the University’s ethics committee, 8 female basketball players (age 21.6 +1.41 years, height 1.70 +0.08 m, mass 64.6 +7.3 kg), 8 male basketball players (age 22.9+ 2.95, height 1.90 +0.19 m, mass 77.1 + 11.7 kg) and 6 additional female basketball players with a history of unilateral ACL reconstruction (ACLr; age Abstracts S21 29.4 + 8.92 years, height 1.70 +0.05 m, mass 67.5 + 9.62 kg) provided written, informed consent. During performance of seven unanticipated cutting tasks, three-dimensional joint and segment kinematics were recorded using an eight digital-camera motion capture system (Motion Analysis Corp.,Santa Rosa, CA, USA) sampling at 240 Hz. Between groups differences in joint and segment coupling variability were evaluated with between group ANOVAs. Furthermore, the explained variance (Z2) for each joint coupling was calculated to demonstrate the magnitude of differences between the three groups. In support of Pollard et al. (2005), females demonstrated reduced variability in two joint couplings (hip abduction-adduction/knee rotation variability (P ¼ 0.03, Z2¼ 0.55) and hip rotation/knee abduction-adduction (P ¼ 0.01, Z2 ¼ 0.61). These differences may be associated with female increased risk of ACL injury (Pollard et al., 2005). Female athletes’ movement patterns may not be variable enough to adapt to environmental constraints during basketball play resulting in ACL injuries. Males displayed the most flexible movements in all couplings. Interestingly, the ACLr group demonstrated variability that was greater than females but less than males in the majority of couplings. This study warrants further investigation into the effects of gender and ACL reconstruction on lower extremity joint coordination variability, and its implications to female injury.