Biomechanical Analysis Of Lower Limbs During Volleyball Blocking Movement With Different Hardness Mid-sole Shoes

Objective: As one of the most popular sports of the ball games,volleyball has far and wide mass-base.With the development of economy and the improvement of scientific researches,people pay more and more attention to the quality of volleyball equipment.Previous studies have shown that differences in the structure and materials of sneakers can improve sports performance and avoid sports injuries effectively.In this study,we analyzed the lower limb kinematics and dynamics data of athletes who wearing different mid-sole hardness sneakers to do right cross-step blocking.The discussing which hardness is most suitable for volleyball players.Methods: A total of 10 experienced volleyball players participated in the tests.Participants were asked to complete tasks of right cross-step blocking with different sneakers of mid-sole hardness.They selected hardness of sneakers are are respectively 40HA/50HA/60 HA.The 8-camera Vicon motion analysis system(Oxford Metrics Ltd.,Oxford,UK)was used to capture subjcets' lower limb kinematics.A Kistler force platform made in Switzerland was synchronized to collect the ground reaction force.The SPSS 19.0 software(SPSS Inc.,Chicago,IL,USA)was used for statistical analysis.The Post Hoc Multiple Comparisons and LSD(least significance difference)of ANOVA(analysis of variance)were taken for data analysis,the significance level was set at 0.05.Results: In terms of kinematics performance,the inner rotation of knee joint is less than that of medium hard soled shoes and hard soled shoes.In the process of landing,as the hardness of the middle sole increases,the flexion activity of the hip joint decreases gradually.When wearing soft-soled shoes,the external rotation of ankle was significantly less than that of hard-soled shoes.In terms of dynamics,the peak value of ground reaction force on landing of soft-soled shoes is smaller than that of medium hard-soled shoes and hard-soled shoes,and the lower the hardness of the middle sole,the longer the peak value will be reached when landing.The maximum loading rate of soft-soled shoes on landing was significantly lower than that of medium hard-soled shoes and hard-soled shoes.When wearing soft-soled shoes,the first 50 ms of impact is significantly less than that of hard-soled shoes.Conclusions and Suggestions: With the increase of the hardness of the middle sole of the shoes,the mobility of the knee joint is also increased,which increases the risk of anterior cruciate ligament injury.The motion range of hip,knee and ankle joints is the largest in the sagittal plane when wearing soft sole shoes in the landing stage,which can effectively cushion the damage caused by the ground reaction force.The risk of injury to knee joint is greater than that of soft-soled shoes.Soft-soled shoes have a larger valgus Angle than the other two,increasing the risk of ankle sprains on the frontal surface.On the dynamics,the cushioning effect of soft-soled shoes is the best,effectively buffering part of the impact force with the ground.It is suggested that the midsole hardness of volleyball shoes is between 40 and 50.