Comparison of Dominant and Non-Dominant Limb Biomechanics in Female Soccer Players

Abstract

The high incidence of anterior cruciate ligament (ACL) rupture in sports, particularly noncontact injuries, warrants determination of risk factors associated with these injuries. The role that leg dominance plays in injury risk during soccer has not been elucidated. One group has suggested injuries differ between the sexes, with women more likely to injure their non-dominant, support leg, but men more likely to injure their dominant, kicking leg (1). Others have reported that leg dominance is not a risk factor (2-3). PURPOSE: The purpose of this study was to compare biomechanical variables between the dominant and non-dominant limbs of female soccer players. METHODS: Thirty-two women from two NCAA Division I soccer teams (20.1 ± 1.2 yrs; 1.7 ± .1 m; 64.3 ± 6.1 kg) underwent biomechanical analyses of two tasks; a triple hop landing (TH) and a single-leg squat (SQ). Knee joint angles and external moments (normalized to mass X height) in the sagittal and frontal planes were assessed at peak knee flexion. Peak knee extension power during the TH landing was also assessed. Paired t-tests were performed to detect differences between biomechanical variables from the self-reported dominant (D) and non-dominant limbs (ND). RESULTS: No between limb differences were observed for the knee angles during the TH (sagittal plane D= 66 ± 9 and ND= 67 ± 10 deg, p=.767; frontal plane D= 7 ± 5 and ND= 6 ±6 deg, p=.360) or the SQ (sagittal plane D= 71 ± 12 and ND= 73 ± 13 deg, p=.333; frontal D= 8 ± 4 and ND= 10 ± 6 deg, p=.175). Additionally, no between limb differences in knee flexion moments for either the TH (D= 1.1± .3 and ND= 1.1 ± .3 Nm/kgm, p=.137) or the SQ (D=1.1 ± .2 and ND= 1.1 ± .3 Nm/kgm, p=.997) were observed. However, knee adduction moments were smaller in the dominant limb during both the TH (D= .35 ± .19 Nm/kgm; ND= .46 ± .22 Nm/kgm; p= .011) and the SQ (D= .24 ± .15 and ND= .31 ± .17 Nm/kgm, p= .030). No between limb differences were present for the TH landing power (p= .767). CONCLUSIONS: The greater knee adduction moments observed on the non-dominant stance limb for both the TH and SD would deter the knee from a deleterious risk knee abduction position, commonly associated with noncontact ACL injury. It is therefore plausible that the between limb differences contribute to women soccer players being more likely to sustain injury to their dominant preferred kicking limb.