Methods: Forty-three subjects (mean and standard deviation for age 21.12 ± 2.00 y, height 168.58 ± 7.62 cm, and weight 60.27 ± 7.80 kg) participated in this study. Kinematic and kinetic variables of lower extremity and trunk during single-leg landing were collected by 5 Vicon cameras and Kistler force plate. Stepwise multiple regression and Pearson correlation were used to identify predictor variables of anterior shear force (P ≤ 0.05). 

Results: Peak of extensor moment (P = 0.004, r = -0.394) and maximum knee flexion (P = 0.007, r = -0.370) were the best predictors that explained 30% of the variance of the shear force data. Therefore, rise in maximum extensors moment of knee and knee maximum flexion causes increase and decrease in anterior shear force, respectively. In addition, a significant relationship between trunk flexion (P = 0.039) and knee flexion angular velocity (P = 0.048) at the moment of initial contact with the anterior shear force. 

Conclusion: On the basis of previous research, and the relationship between clinical findings, the noncontact of anterior cruciate ligament injury during landing was confirmed. These results can be used in prospective studies examining modifiable noncontact risk factors of ACL injury.