Biomechanical Asymmetry Study Between The Kicking And Stance Limbs In Soccer Player

Objective:The purpose of this study was to investigate the influence of asymmetry between the kicking and the stance limbs of soccer player on the impact of sports injury. We analysis the asymmetry from the lower limb joint muscle strength and biomechanical characteristics in the cutting and stop-jump landing, to find asymmetry influence on sports injury, at the same time to provide theory support for the guidance and improve training methods.Methods:Twelve man soccer athletes from Beijing Sport University participated in this study. Using the Isokinetic testing system to test the lower limb knee and ankle flexion and extend muscle strength of both sides in 60°/s and 180°/s. Using the infrared high speed Motion capture system and 3D measuring force platform synchronous acquisition kinematics and kinetics data in the 45°cutting and stop-jump landing.Results:In the lower limb muscle strength of constant speed test, there are no significant difference between the kicking and stance limbs in the knee joint flexion and extension value of torque at both speed of 60°/s and 180·/s, there is no significant difference in the flexor/extensor knee ratio too; There is no significant difference of ankle plantar flexors peak torque at both speed of 60°/s and 180°/s, but the extensor peak torque is significantly higher than the stance limb. In the kinematics and kinetics test, there is no significant difference between the kicking and stance limbs of the first peak of vertical ground reaction force and the first peak of level ground reaction force; In cutting the hip flexion angle of kicking limb is less than the stance limb, but the ankle plantar flexion angle is significantly greater than the stance limb, the ankle joint represented external rotation torque and the stance limb ankle joint represented rotation torque. In stop-jump landing, the kicking limb hip joint external rotation and the stance limb hip joint rotation, knee and ankle joint represented external rotation torque and the stance limb represented rotation torque. Landing buffer phase, the kicking limb ankle plantar flexion is greater than the stance limb at the touchdown moment but the range of inflexion is less than the stance limb, ankle varus in maximum and range are significantly less than the stance limb; The hip external rotation torque peak and knee adduction torque are significantly higher than that of stance limb.Conclusions:(1) Kicking limb and stance limb exerts asymmetry in ankle extensor muscle peak torque, but there is no asymmetry in the knee and ankle joint muscle group peak torque. (2) In cutting and stop-jump landing, there are significant differences in the kinematics and kinetics index that lead to injury between the kicking and stance limb.