Effect Of Fatigue And Unanticipated Factor On Lower Limb Joint Biomechanics During Change Of Direction Maneuver Among Female Football Players

Purpose:Non-contact ACL is a common knee injury which often happened in high speed cutting maneuver in football,especially for female in side cutting and pivot movements.It has found that unanticipated or fatigue factors would lead to declines of motor performance and increase the risk of ACL injury.However,the biomechanical effects of fatigue and unanticipated factors on side cutting and pivot movements were rare,and no consistent conclusions were made.A new protocol with more football fatigue characteristic and unanticipated direction change were used to investigate the interaction or main effect of the fatigue and unanticipated factors to hip,knee and ankle joint kinematics and kinetics of female football athletes mainly.Then discussed the biomechanical mechanism of non-contact ACL injury risk during side cutting and pivot movements.Methods:21 female college football athletes were recruited in Shanghai.Side-cutting and pivot movements under anticipated and unanticipated conditions before fatigue were tested.Then,they were induced to fatigue according to the established fatigue program.At last,a test which was the same as before fatigue was taken.Infrared motion system(T40 cameras,Vicon Motion Analysis,UK),38 reflective marker balls and one force plate(9287C,Kistler Instruments AG Corp.,Switzerland)were used to collect data.Visual 3D(C-Motion,Inc.,USA)was used to calculated the data,fourth worth Butterworth was used to filter the data.Body model was built and data calculation was made based on this,and then all the kinetic and kinematic variables was output,and two-way ANOVA with repeated measures was used to test the difference.Results:1)The interaction of fatigue and unanticipated factors was not significant on the kinematics and kinetics of the hip,knee and ankle joints of the lower limb during side-cutting(P > 0.05).The interaction of fatigue and unanicipated factors was significant on internal and external rotation ROM of hip and ankle joint,flexion and extension moment of hip,knee and ankle joint in sagital plane during pivot task(P < 0.05).Simple effect test was used to test the internal and external rotation ROM of hip and ankle joint,flexion and extension moment of hip,knee and ankle joint in sagital plane after fatigue under the anticipate conditions.The internal and external rotation ROM of ankle joint were significantly less than before fatigue(P < 0.05),but the internal and external rotation ROM of hip and the hip extension moment,knee flexion moment and ankle flexion moment were significantly increase than those before fatigue(P < 0.05),but under unanticipated condition,there was no significant difference in ROM of hip and ankle internal and external rotation,flexion and extension moments of hip,knee and ankle joints before and after fatigue(P > 0.05).2)The effect of fatigue on the kinematics of side-cutting manuvour was not significant(P > 0.05),but the effect of fatigue on the inversion moment of frontal plane of hip joint,knee joint and ankle joint were significant(P < 0.05).The results show that the joint inversion moment decreased significantly after fatigue compared with before fatigue,and the inversion moment changed from inversion to eversion in unanticipated condition after fatigue(P < 0.05).The fatigue factor was significant affect the valgus and varus ROM of knee joint during the pivot task.The valgus ROM increased after fatigue(P < 0.05).The fatigue factor was significant affect the ground reaction force and the loading rate of the peak Vertical Ground Reaction Force loading rate duting the pivot task(P < 0.05).The Vertical Ground Reaction Force,Posterior Horizontal Ground Reaction Force and Lateral Ground Reaction Force after fatigue were significantly less than before fatigue.the first peak loading rate of Vertical Ground Reaction Force decreased significantly(P < 0.05).3)Compared with anticipated factor,unanticipated factor effect significantly affected the kinematics and kinetics of hip,knee and ankle joint during side cutting and pivot movements(P < 0.05).Conclusion:1)The fatigue and anticipated factors would not have simultaneous effects on the side cutting and pivot movements,which indicate the fatigue and unanticipated factors would not increase the risk of ACL injury while exist at the same time?2)Compare with pre-fatigue,valgus moment influence the hip and knee joint during side cutting movement after fatigue,which would decrease the stability of these joint;Vertical Ground Reaction was decreased during pivot movement,which might affect the performance of athletes after fatigue.3)Compare with anticipated condition,different lower extremity kinematic and kinetic loading strategies were adopted under unanticipated condition during side cutting and pivot movements,which would increase the risk of ACL injury.4)In the unanticipated condition,compare with side cutting,the athletes presented a more erect posture which would increase the risk of ACL injury during the pivot task.