The Effects Of Approach Run Speeds On Lower Extremity Biomechanical Characteristics Of Volleyball Players During Stance Phase In Stop-Jump Tasks

Purposes:This article aims to explore the impact of changing the approach run speeds in stop-jump tasks on three-dimensional kinematics and kinetics characteristics of lower extremity of volleyball players,so as to provide a scientific basis for the injury mechanisms,injury prevention and rehabilitation of lower extremity in volleyball.Methods:The 8-lens,5 million-pixel three-dimensional Qualisys infrared motion capture system and two three-dimensional Kistler force plates were used to collect the kinematics and kinetics signals of the subjects when they completed the stop-jump tasks at different approach run speeds.The sampling frequency was set as 200Hz and 1000Hz.Qualisys Track Manager 2019.2 and Visual3D software were used to collect,process and obtain the joint angles,joints moments and ground reaction force of the hip,knee and ankle joints in the sagittal,frontal and horizontal planes.SPSS 23.0 statistical software was used for statistical analysis.Two-factor Mixed-design ANOVA was used to compare the effects of approach run speeds and gender on kinematics and kinetics characteristics of lower extremity.Results:1.There is no interaction between approach run speed and gender,but there are significant differences between approach run speedThe hip abduction angle at initial ground contact,peak hip abduction angle,peak knee extension angle,peak knee internal rotation angle and peak hip adduction moment at slow approach run speed were significantly smaller than those at medium and fast approach run speeds(P<0.05).The faster the approach run speeds,the smaller the peak hip extension angle,and the greater the peak ankle plantar flexion angle,the peak ankle internal rotation angle,the peak knee extension moment and the peak posterior ground reaction force(P<0.05).The peak ankle varus moment at fast approach run speed was significantly greater than that at slow approach run speed(P=0.026).2.There is no interaction between approach run speed and gender,but there are significant differences between genderFemale volleyball players’ ankle external rotation angle at initial ground contact,peak knee valgus angle,peak ankle external rotation angle,peak knee varus moment,peak ankle valgus moment and peak posterior ground reaction force were significantly greater than those of male volleyball players,while the peak knee varus angle,peak ankle internal rotation angle,peak hip extension moment,peak knee flexion moment,peak ankle dorsiflexion,plantar flexion moment and varus moment were significantly smaller than male volleyball players(P<0.05).3.There is interaction between approach run speed and gender,and there are significant differences between approach run speedThe faster the approach run speeds,the smaller the peak hip flexion angle of female volleyball players,the greater the peak hip adduction angle and the peak vertical ground reaction force(P<0.05),and the peak hip abduction moment at slow approach run speed was significantly smaller than that of medium approach run speed(P<0.001).At fast approach run speed,male volleyball players’ peak hip flexion angle and peak knee valgus moment were significantly smaller than those at slow approach run speed,and peak hip abduction moment and peak vertical ground reaction force were significantly greater than those at slow and medium approach run speeds(P<0.05).4.There is interaction between approach run speed and gender,and there are significant differences between genderAt fast approach run speed,the peak hip abduction moment of female volleyball players was significantly smaller than that of male volleyball players(P=0.016).Conclusion:1.The approach run speed significantly affects the kinematics and kinetics characteristics of lower extremity.At slow approach run speed,the smaller peak hip abduction angle,the peak knee extension angle,the peak ground reaction force,the mechanical load on the frontal plane of the hip joint and the mechanical load on the sagittal plane of the knee joint can reduce the mechanical load on the knee joint,reduce the risk of knee joint injury.2.Gender significantly affects the kinematics and kinetics characteristics of lower extremity.Compared with male volleyball players,female volleyball players have greater peak knee valgus angles,peak ankle external rotation angles,peak posterior ground reaction force,and mechanical loads on the sagittal and frontal planes of the knee and ankle joints which contributes to the higher mechanical load on knee and ankle joints,increases the risks of injury.3.At slow approach run speed,male and female volleyball players have greater hip flexion angles,which can improve the landing cushioning;at the same time,the smaller hip abduction moment,knee valgus moment and vertical ground reaction force mean less mechanical load on the knee joint.