| Research purpose:With the emphasis on football in China,the love of football fans and the expectation of the development of football in China,both competitive and popular football are developing rapidly,and the society and the state are gradually investing more and more human and material resources in football.Research into the relationship between performance and injury in football and football footwear is of great importance to the development of football in China,and the results will have a wide and far-reaching impact on football training and public sport,promoting the development of football.However,there are few comprehensive studies in this area.In this study,two typical football technical movements,namely the side-cut and the stop-and-go,were selected to observe the regular characteristics of the biomechanical parameters of human lower limbs in different football cleat configurations on different turf sizes,so as to study the effects of football cleat size and turf size on athletic performance and sports injuries of athletes.Research method:In this study,15 male football players（age 20 years ± 5 years,height 1.72 m ± 0.05 m,weight 65.5kg ± 5kg）of national level 2 and above were selected.Two types of experiments were carried out: experiment 1,8 players wearing AG（Artificial Ground）and SG（Soft Ground）shoes on natural turf to perform a sharp turn and a 45° side cut;experiment 2,15 players wearing AG and SG shoes on artificial turf to perform a sharp turn and a 45° side cut,using three high-speed cameras and a kistler force gauge.Three high-speed cameras and a kistler dynamometer were used to synchronise the kinematic and kinetic data during the 45°sidestep and the sharp stop-and-go.The kinematic and kinetic data were further processed using Visual 3D software and the data were expressed as mean ± standard deviation.The data were then statistically analysed using SPSS 20.0 software.The analysis was performed using both paired samples t-test and independent samples t-test for both kinematic as well as kinetic data,with the significance level set at p<0.05.Results :1)Analysis of variance for right leg support touchdown time in 45°lateral cut on both turf with AG and SG football cleats,no significant difference in touchdown time（P>0.05）.2)ANOVA for knee angle in sharp stop and go and 45°lateral cut on both turf with AG and SG football cleats,results（P>0.05）,peak knee flexion angle,minimum knee flexion angle,flexion mobility 3)An ANOVA of ankle joint angles for the AG and SG football cleats on the two turf surfaces with a sharp stop-and-go return resulted in（P>0.05）,with no significant differences in peak ankle dorsiflexion angle,peak plantarflexion angle,or flexion mobility.4)The peak ankle dorsiflexion angle for 45° lateral cuts on artificial turf was significantly greater than that for SG on natural turf,P=0.0002 and P=0.0004,respectively（P<0.001）.The ankle plantarflexion angle of 45° lateral cut with AG on natural turf was not significantly different,（P>0.05）.5)The ankle flexion mobility of 45° lateral cut with both types of football shoes on artificial turf was significantly greater than that of SG on natural turf,P=0.0006,P=0.0006,a significant difference（P<0.001）.The ankle flexion mobility of 45° lateral cut with AG on natural turf was not significantly different from the other,P>0.05.6)There was no significant difference in PVF between subjects wearing SG and AG on natural turf versus artificial turf during the right leg support phase of the sharp stop-and-go and 45° lateral cut manoeuvres（P>0.05）.Conclusion:1)Conclusions related to turf:The trend of the angle change curve shows that natural turf,compared to artificial turf,may require a greater knee flexion angle to reduce the impact force during exercise due to the stronger grip and impact force.2)Conclusions related to different types of football shoes:（1）The trend of the angle change curve shows that AG has a greater knee flexion angle compared to SG angle,probably due to the lack of cross penetration of the spikes with the turf during the sport,and the increased knee flexion angle helps to ensure adequate grip.（2）The AG football cleat has a higher overall adaptability on both turf types.（3）From conclusions four and five,it can be concluded that SG football shoes are more suitable for use on natural turf,increasing grip while having less stress in the vertical direction and not requiring an increased knee flexion angle to reduce impact.3)Conclusions on technical movements:（1）This may be due to the greater stress on the knee joint and the stimulation of joint movement,which may make the knee joint more susceptible to injury during a stop-and-go.（2）The trend towards a more pronounced change in ankle angle with 45° lateral cuts may be due to greater joint stress stimulation,and45° lateral cuts may be more likely to cause a non-contact injury to the ankle. |
