儿童背不同质量书包步态终止时动力学分析

Kinetics analysis on gait termination for children with backpacks

目的了解儿童步态终止时动力学特征,比较有计划步态终止(planned gait termination,PGT)和急停(unplanned gait termination,UPGT)时的差异,以及书包质量对儿童步态终止的影响。方法通过室内模拟步态终止发生场景,经两个三维测力台记录12名男孩(年龄(9.85±1.34)岁,身高(140.89±11.57)cm,体重(34.96±9.62)kg)背不同质量书包完成PGT和UPGT过程中地面反作用力及足底压力中心(center of pressure,COP)位移变化。结果 PGT和UPGT过程中地面反作用力曲线与行进中步态有明显差异,地面反作用力峰值和COP偏移均显著大于行进中步态,且差异随书包质量增加而增大,背15%体重(15%BW)书包急停时最大。结论儿童在步态终止时地面反作用力趋向有利于完成步态终止的方向变化,但身体所受冲击力可能随之增大,且随书包质量增加而增大;步态终止时控制姿势平衡的难度加大。建议儿童宜减轻书包质量,可能有助预防突发干扰时发生意外损伤。

Objective To understand kinetics characteristics of gait termination for children with backpacks, and compare the difference between planned gait termination （PGT） and unplanned gait termination （UPGT） as well as effects of backpack carrying by children at the moment of gait termination. Methods Twelve boys （age （9.85 ± 1.34） years old, height （ 140.89 ± 11.57） cm, weight （34.96 ±9.62） kg） were recruited in this study. The gait termination scene in real life was simulated in the lab by the subjects who were required to carry different back- packs, while the parameters of ground reaction force and center of pressure （COP） during PGT and UPGT were recorded by two 3D force plates. Results There were significant differences in the peak ground reaction force curve between gait termination and normal walking. Meanwhile the peak ground reaction force and COP shifting during PGT and UPGT were both significantly larger than those during normal walking, and the values were in- creased with the increase of backpack load. The maximum ground reaction force and COP shifting were found during UPGT while the subject was carrying backpack equal to 15% of the body weight （ 15% BW）. Conclusions The change of ground reaction force was useful for gait termination, but children will suffer much more impact force during both PGT and UPGT, and make the control on postural balance more difficult, which could be dan- gerous with the increase of backpack load. It is advised that children should lighten their backpack loads, which will be helpful to prevent accidental injuries during suddenly external disturbance.