The relationship between executed cut angle and speed with lower extremity joint angles during unanticipated side-step cutting in soccer players

Background: Certain movements patterns have been indicated in knee injuries during cutting while running tasks. Differences in the executed cut angle (ECA) could partially account for group differences in joint kinematics previously observed, including sex differences. Research question: Are there relationships between joint angles with entry speed and ECA during side-step cutting in soccer players? Methods: This cross-sectional study recruited 21 (10 females) soccer players. Participants completed 45 degrees unanticipated side-step cuts in both directions. Kinematic data were captured with a 12 camera motion capture system with 46 reflective markers placed on the participants. Peak joint angles were determined during the stance phase of the cutting task. Entry speed and ECA were determined from pelvis markers. Hierarchical linear models examined relationships between angles, entry speed, and ECA, after accounting for age, sex, and leg preference. Regression coefficients with 95 % confidence intervals were reported and statistical significance (p<0.05) were examined using the Wald statistic. Results: The mean ECA (24.6 degrees) was lower than the intended 45 degrees angle. Peak joint angles were significantly related to both ECA and entry speed. Specifically, an increase in ECA by 10 degrees (i.e., sharper cuts) would increase hip internal rotation and ankle plantarflexion by 1.8-2.1 degrees, and decrease hip adduction, knee abduction and ankle eversion by 1.3-2.4 degrees. Faster entry speeds by 0.5 m/s would increase hip flexion, hip internal rotation and knee extension angles by 1.8-3.8 degrees, and decrease knee abduction by 2.6 degrees. Significance: Studies evaluating cutting while running should consider ECA and entry speed in their design. Potential differences could confound between-group comparisons of joint angles, including when comparing sexes, and impact interpretations of injury risk.