The Study Of The Effects Of The Sports Surface Switching On The Biomechanics Of Lower Extremity During Running

Objective: To explore the effects of common surface switching on lower limb joints by changing the sequence of moving surface switching during running.By analyzing the kinetic data and kinematic data during the experiment,we can understand the lower limbs of the human body when switching between different moving surfaces.The results of this study are expected to provide a theoretical basis for injury prevention and running training guidance,to achieve the purpose of preventing injury and improving athletic performance.At the same time,it provides certain reference and suggestions for runners to switch running on different sports surfaces in outdoor environment;It is expected to provide a new idea for subsequent research.Methods: Two different types of moving surface plates were prepared and combined into a runway and laid on a force measuring platform.The moving surface was 15 mm thick,and the two were plastic and cement.In this study,11 ordinary male college students were recruited from the non-sports majors of Beijing Sport University,and the first floor experimental hall of the China Sports and Health Research Institute of Beijing Sport University was selected as the test site.Four sets of subjects under moving surface switching were acquired during the movement by simultaneously using a three-dimensional force measuring table(Kistler 9281 CA,Switzerland,1000 Hz)and an 8-shot high-speed infrared spot motion capture system(Motion Analysis Raptor-4,USA,200 Hz).The data is identified,modeled,output raw data and processed by software such as Microsoft Office Excel 2010 through the Helen-Hayes model of Motion Analysis software Cortex2.1.0.1103.The three-dimensional coordinates of all landmarks were smoothed using Butterworth low-pass filtering with a cutoff frequency of 12 Hz.Data were processed by the SPSS 20.0 statistical software package and statistically analyzed by one-way repeated measures ANOVA.The statistical significance level is defined as a type of error probability of no more than 0.05.Results: 1)Landing moment: The net moment of the ankle joint showed statistical difference(p=0.038);2)The moment of leaving the ground: the angle of the ankle joint(p=0.008),the angle of the knee joint(p=0.005),the angle of the hip joint(p= 0.033)and net net moment of knee joint(p=0.021)showed statistical difference;3)support stage: maximum net moment of ankle joint(p=0.001),minimum net moment of ankle joint(p=0.002),knee joint The net torque minimum(p=0.010)and the hip net net maximum(p=0.006)showed statistical differences;4)joint stiffness: knee joint stiffness(p=0.001)and ankle flexion maximal moment The amount of ankle moment change(p=0.016)showed statistical difference;5)the maximum value of ground release force in the support phase showed statistical difference(p=0.029).Conclusion: 1)When the moving surface is switched,it is more likely to cause the joint stiffness of the knee joint to be reduced when the moving surface is not switched,which may increase the risk of the runner's motion damage of the lower limb joint during the switching of the moving surface,especially The possibility of injury to the knee joint;2)Through the comprehensive analysis of the joint stiffness of the knee joint and the joint torque variation of the ankle joint,the hardness of the moving surface at the start of the race may also become another cause of lower limb damage during running.Influencing factors,the ground reaction forces switching on different sports surfaces during running are different,and the ground reaction force on the concrete floor is relatively higher;in this study,the performance is switched from the cement moving surface(harder).When the plastic sports surface(softer)is used,the risk of injury to the lower limbs is increased,and the data of the group in which the surface switching occurs is significantly different from the group that does not switch,and the risk of injury is increased;3)when starting from the same plastic or when switching to different moving surfaces after the cement starts running,it shows The flexion angle and moment of the lower extremity joints on the cement surface are more variable.It can be inferred that the risk of injury to the lower extremity joints will be higher at this time;4)During the switching process of different moving surfaces during running,the joint dynamic angles and moments of the lower limbs are related.The differences are very obvious.Compared with the movement from the cement surface to the plastic surface,the change from the plastic surface(softer)to the cement surface(harder)on the knee joint net moment change,the angle change is larger,the joint stiffness is greater;the ankle joint The amount of change in net torque is small,the amount of angle change is large,and the joint stiffness is small.It can be inferred that the risk of injury to the ankle joint is increased at this time.