Pires Neville J, Lay Brendan S, Rubenson Jonas
School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, WA 6009, Australia.
School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, WA 6009, Australia
J Exp Biol. 2014 Oct 1;217(Pt 19):3519-27. doi: 10.1242/jeb.107599. Epub 2014 Aug 7.
Two commonly proposed mechanical explanations for the walk-to-run transition (WRT) include the prevention of muscular over-exertion (effort) and the minimization of peak musculoskeletal loads and thus injury risk. The purpose of this study was to address these hypotheses at a joint level by analysing the effect of speed on discrete lower-limb joint kinetic parameters in humans across a wide range of walking and running speeds including walking above and running below the WRT speed. Joint work, peak instantaneous joint power, and peak joint moments in the sagittal and frontal plane of the ankle, knee and hip from eight participants were collected for 10 walking speeds (30-120% of their WRT) and 10 running speeds (80-170% of their WRT) on a force plate instrumented treadmill. Of the parameters analysed, three satisfied our statistical criteria of the 'effort-load' hypothesis of the WRT. Mechanical parameters that provide an acute signal (peak moment and peak power) were more strongly associated with the gait transition than parameters that reflect the mechanical function across a portion of the stride. We found that both the ankle (peak instantaneous joint power during swing) and hip mechanics (peak instantaneous joint power and peak joint moments in stance) can influence the transition from walking to running in human locomotion and may represent a cascade of mechanical events beginning at the ankle and leading to an unfavourable compensation at the hip. Both the ankle and hip mechanisms may contribute to gait transition by lowering the muscular effort of running compared with walking at the WRT speed. Although few of the examined joint variables satisfied our hypothesis of the WRT, most showed a general marked increase when switching from walking to running across all speeds where both walking and running are possible, highlighting the fundamental differences in the mechanics of walking and running. While not eliciting the WRT per se, these variables may initiate the transition between stable walking and running patterns. Those variables that were invariant of gait were predominantly found in the swing phase.
关于步行到跑步转换（WRT），两种常见的力学解释包括防止肌肉过度劳累（用力）以及将肌肉骨骼峰值负荷降至最低，从而降低受伤风险。本研究的目的是通过分析速度对人类离散下肢关节动力学参数的影响，在关节层面验证这些假设，研究范围涵盖广泛的步行和跑步速度，包括高于WRT速度的步行和低于WRT速度的跑步。在装有测力板的跑步机上，收集了8名参与者在10种步行速度（其WRT的30 - 120%）和10种跑步速度（其WRT的80 - 170%）下，踝关节、膝关节和髋关节矢状面和额状面的关节功、峰值瞬时关节功率以及峰值关节力矩。在分析的参数中，有三个符合我们关于WRT“用力 - 负荷”假设的统计标准。与反映步幅一部分机械功能的参数相比，提供急性信号的力学参数（峰值力矩和峰值功率）与步态转换的关联更强。我们发现，踝关节（摆动期峰值瞬时关节功率）和髋关节力学（站立期峰值瞬时关节功率和峰值关节力矩）都可影响人类运动中从步行到跑步的转换，可能代表了一系列始于踝关节并导致髋关节不利代偿的机械事件。与以WRT速度步行相比，踝关节和髋关节机制都可能通过降低跑步时的肌肉用力来促成步态转换。尽管所检查的关节变量中很少有符合我们WRT假设的，但大多数在所有可行的步行和跑步速度下从步行转换为跑步时都呈现出普遍显著的增加，凸显了步行和跑步力学的根本差异。虽然这些变量本身并未引发WRT，但它们可能启动稳定步行和跑步模式之间的转换。那些与步态无关的变量主要出现在摆动期。
