A Comparative Study Of The Biomechanical Characteristics Of The Lower Limbs Under Different Weight-bearing Lateral Cutting Movements

Objective:This study analysed the lateral cutting manoeuvre under different weight-bearing rates(0 weight-bearing,10%BW weight-bearing,20%BW weightbearing).By comparing the differences in the kinematic and kinetic characteristics of the lower limb when completing the lateral cutting manoeuvre under different weightbearing conditions,and by combining the biomechanical theory of lower limb injury in the lateral cutting manoeuvre,we investigated whether weight-bearing has an adverse effect on the lateral cutting manoeuvre,leading to the occurrence of injury,in order to provide a theoretical basis for the prevention of lower limb injury in the lateral cutting manoeuvre that may be caused by weight-bearing.Methods:In this study,16 healthy male subjects with a certain level of athletic activity were selected from a volunteer database and were asked to perform lateral cuts under different load conditions(0,10%BW,20%BW),and the kinematic parameters(time,joint angle,joint angular velocity)and kinetic parameters(joint moment,ground reaction force in three directions)of the three joints of the lower limb of the supported leg during the lateral cuts under different load conditions were collected using the VICON infrared motion capture system and the KISTLER 3D force measuring table.One-way ANOVA was used to analyse the differences in the biomechanical indices of the lower limbs with different weight-bearing lateral cuts,If the data do not conform to a normal distribution then a non-parametric test is used.followed by posthoc multiple comparisons using the LSD method to observe the changes in the biomechanical indices of the lower limbs with different weight-bearing lateral cuts.Results:(1)Kinematic parameters:1)The cushion time increased significantly with increasing weight,and increased significantly with 20%BW compared to 0 weight(P<0.05).2)The hip flexion angle,knee flexion angle,knee valgus angle,ankle dorsiflexion angle,and ankle dorsiflexion angle tended to increase with increasing weight at the moment of touchdown of the lateral cut with different weight.The increase in hip flexion angle,knee flexion angle,knee valgus angle,and ankle dorsiflexion angle tended to increase with increasing weight,compared to zero weight,at 10%BW load(P<0.05);at 20%BW load(P<0.01);and at 20%BW load(P<0.01).3)Lateral cut movement At the moment of maximal cushioning,hip flexion angle,hip internal rotation angle,knee flexion angle,knee valgus angle,knee internal rotation angle,all showed a tendency to increase with increasing deadlift weight,and there was a significant increase in hip flexion angle,hip internal rotation angle,knee flexion angleknee valgus angle and knee internal rotation angle at 20%BW deadlift compared to 0 deadlift(P<0.05).4)At the moment of the first peak of VGRF for the lateral cut manoeuvre,the Hip abduction angle,knee flexion angle,knee valgus angle and knee flexion angle velocity all showed an increasing trend with increasing weight bearing.Compared to 0 weight bearing,there was a significant difference in the increase in hip abduction angle,knee flexion angle and knee valgus angle at 20%BW weight bearing(P<0.05)and a highly significant difference in the increase in knee flexion angle velocity(P<0.01).(2)Kinetic parameters:1)The peak PGRF(peak horizontal backward ground reaction force)increased significantly with the weight of the different weight-bearing lateral cuts,with a significant difference in the increase in peak PGRF at 10%BW weight-bearing compared to 0 weight-bearing(P<0.05).a highly significant difference in the increase in peak PGRF at 20%BW weight-bearing(P<0.01)2)At the moment of touchdown of the lateral cut,the hip extension moment and knee extension moment increased with the weight of the load under different weight of the lateral cut,and the increase of the hip extension moment and knee extension moment was significantly different at 20%BW weight compared with 0 weight(P<0.01).3)At the moment of maximum cushioning of the lateral cut.hip extension moment,knee extension moment,knee valgus moment,and knee external rotation moment showed a tendency to increase with increasing deadlift weight,and compared with 0 deadlift,at 20%BW deadlift,hip extension moment,knee extension moment,knee valgus moment,and knee external rotation moment were significantly increased(P<0.05).4)At the moment of the first peak of VGRF of the lateral cut.hip extension moment,hip valgus moment,knee external rotation moment,and knee external rotation moment were significantly increased(P<0.05).hip external rotation moment,knee extension moment,knee valgus moment,and knee external rotation moment all showed an increasing trend with increasing deadlift weight.Compared with 0 deadlift weight,there was a significant difference in the increase of hip extension moment at 10%BW deadlift(P<0.05);at 20%BW deadlift,there was a significant difference in the increase of knee external rotation moment(P<0.05),and the increase of hip extension moment,knee extension moment,and knee valgus moment The differences were highly significant(P<0.01).Conclusions:(1)When the weight was increased,the subjects tried to cushion the increased ground impact by prolonging the cushion time,but the prolongation of the cushion time affected the centripetal contraction ability of the muscles in the subsequent stirrup extension phase and the quality of the entire lateral cut completion.(2)When the weight increases,the human body relies on adjusting the flexion angle of the hip and knee in the sagittal plane to increase the displacement of the lower limb joints in the sagittal plane to reduce the impact of the weight,thus ensuring the stability of the landing to cushion the impact of the ground.(3)When the weight increases,despite the conservative landing strategy,the human body still has some negative effects on its dynamic characteristics.Subjects exhibited greater backward ground reaction forces,greater knee extension moments,and greater knee valgus moments,all of which predicted increased loading on the lower extremities with increased weight bearing,increasing the risk of ACL injury.(4)When completing the lateral cut with less weight,the human body mainly takes the mode of knee flexion to land,and when completing the lateral cut with more weight,the human body increases the angle of knee flexion and hip flexion at the same time when landing,which may be caused by the increased load on the lower limbs when carrying more weight.