The Local Dynamic Stability Analysis Of Runners’ Lower Limb Joints Under The Different Running Shoes

Background: The local dynamic stability,the sensitivity of the system to slight disturbances,refers to the ability of the human neuromuscular system to attenuate external disturbances.By analyzing non-linear time-series data with local dynamic stability,it is possible to quantify captured subtle disturbances(such as gait interference from stride-to-stride fluctuations)as the divergences of motion trajectories at multiple moments.It can not only evaluate the kinematic changes in the gait but also the kinematic alternations between the gait and gait,achieving the goal of evaluating the dynamic balance of the human body.The purpose of this study was to investigate the differences between the minimalist running shoes and maximalist running shoes on the local dynamic stability of knee and ankle joints during running,comparing to conventional running shoes,to provide advice for runners’ shoe selection.The local dynamic stability was evaluated by the largest Lyapunov exponent.Methods: 12 male college students were recruited in this experiment.All subjects were shod runners wearing conventional running shoes and the dominant side was the right leg.In this study,the inertial measurement unit sensor(IMU)was utilized to collect the joint acceleration data from the lower limb of runners during they were running continuously on a treadmill at a speed of10.8±0.5km/h.The data includes acceleration and angular acceleration of the knee and ankle joints.Firstly,the comparison of the peak resultant accelerations was conducted among the three types of running footwear(maximal shoes: group A,conventional shoes: group B,minimal shoes: group C).Then,using the Rosenstein algorithm to calculate the maximum Lyapunov exponent value of each group to evaluate the impact of different running shoes on the local dynamic stability of the runners’ knee and ankle joints during running.In the statistical analysis software Graph Pad Prism(?),one-way ANOVA was utilized to analyze the significance among three types of running footwear groups.Tukey HSD post hoc test was used to compare the significance between groups.The significance level was set to P <0.05.Results:(1)All peak data of resultant acceleration and angular acceleration in the conventional running shoe group was larger than the maximalist running shoe group and smaller than the minimalist running shoe group,and the pairwise comparison between all groups had the significant differences(P <0.01);(2)Three types of running shoes showed a significant difference in the largest Lyapunov exponent of the subjects’ resultant acceleration of ankle joint(P = 0.018).The comparison between group A and group C had a significant difference(P = 0.014): comparing to the minimalist running shoes,the maximalist running shoes significantly increased the largest Lyapunov exponent value of the resultant acceleration of ankle joint;(3)It also had a significant change in the largest Lyapunov exponent of the runners’ knee joint resultant accelerations(P <0.01).The comparison between group A and group C had a significance statistically(P = 0.0003): the maximalist running shoes increased the largest Lyapunov exponent value of the resultant acceleration of knee joint;(4)The comparison between group B and group C showed a statistical difference(P = 0.0003):comparing to the minimalist running shoes,conventional running shoes significantly increased the largest Lyapunov exponent value of the resultant acceleration of knee joint.Conclusion and Implication:(1)During running,for these three types of running shoes,the peak resultant acceleration data of the knee and ankle joints showed the overall trend that the minimalist running footwear group being the largest and the maximalist running shoes group being the smallest.From the perspective of joint’s peak acceleration,the maximalist running shoes have better cushioning and shock-absorbing effects than the other two types of running shoes and the peak tibial acceleration is smaller during landing;(2)For the resultant acceleration of knee and ankle joints,the maximum Lyapunov exponent value of the minimalist running shoe group was smaller than the maximalist running shoe group.From the perspective of local dynamic stability,the minimalist running shoes have better local dynamic stability of the lower limbs during running than the other two types of running shoes.So,it’s able to attenuate external disturbances in the human neuromuscular system;(3)The traditional running footwear group has smaller peak joint acceleration and better local dynamic stability,which is a better choice for runners who want to take into account the cushioning and dynamic stability of running.