Davis Daniel J, Challis John H
Biomechanics Laboratory, The Pennsylvania State University, University Park, USA.
Biomechanics Laboratory, The Pennsylvania State University, University Park, USA.
J Biomech. 2023 Apr;151:111529. doi: 10.1016/j.jbiomech.2023.111529. Epub 2023 Mar 7.
The arch of the human foot has historically been likened to either a truss, a rigid lever, or a spring. Growing evidence indicates that energy is stored, generated, and dissipated actively by structures crossing the arch, suggesting that the arch can further function in a motor- or spring-like manner. In the present study, participants walked, ran with a rearfoot strike pattern, and ran with a non-rearfoot strike pattern overground while foot segment motions and ground reaction forces were recorded. To quantify the midtarsal joint's (i.e., arch's) mechanical behavior, a brake-spring-motor index was defined as the ratio between midtarsal joint net work and the total magnitude of joint work. This index was statistically significantly different between each gait condition. Index values decreased from walking to rearfoot strike running to non-rearfoot strike running, indicating that the midtarsal joint was most motor-like when walking and most spring-like in non-rearfoot running. The mean magnitude of elastic strain energy stored in the plantar aponeurosis mirrored the increase in spring-like arch function from walking to non-rearfoot strike running. However, the behavior of the plantar aponeurosis could not account for a more motor-like arch in walking and rearfoot strike running, given the lack of main effect of gait condition on the ratio between net work and total work performed by force in the plantar aponeurosis about the midtarsal joint. Instead, the muscles of the foot are likely altering the motor-like mechanical function of the foot's arch, the operation of these muscles between gait conditions warrants further investigation.
人类足弓在历史上一直被比作桁架、刚性杠杆或弹簧。越来越多的证据表明，穿过足弓的结构会主动储存、产生和消散能量，这表明足弓可能还具有类似发动机或弹簧的功能。在本研究中，参与者在地面上行走、以足跟先着地的方式跑步以及以非足跟先着地的方式跑步，同时记录足部各节段的运动和地面反作用力。为了量化中跗关节（即足弓）的力学行为，定义了一个制动 - 弹簧 - 发动机指数，即中跗关节净功与关节总功大小的比值。该指数在每种步态条件下均有统计学显著差异。指数值从行走时到足跟先着地跑步时再到非足跟先着地跑步时逐渐降低，这表明中跗关节在行走时最像发动机，在非足跟先着地跑步时最像弹簧。足底腱膜中储存的弹性应变能的平均大小反映了从行走到非足跟先着地跑步时足弓类似弹簧功能的增强。然而，考虑到步态条件对足底腱膜围绕中跗关节的力所做的净功与总功之比缺乏主要影响，足底腱膜的行为无法解释在行走和足跟先着地跑步时足弓更像发动机的情况。相反，足部肌肉可能在改变足弓类似发动机的力学功能，这些肌肉在不同步态条件下的作用值得进一步研究。
