Villeger David, Costes Antony, Watier Bruno, Moretto Pierre
Université de Toulouse, UPS, PRISSMH, 118 route de Narbonne, F-31062 Toulouse Cedex 9, France.
Université de Toulouse, UPS, PRISSMH, 118 route de Narbonne, F-31062 Toulouse Cedex 9, France.
J Biomech. 2014 Dec 18;47(16):3862-7. doi: 10.1016/j.jbiomech.2014.10.012. Epub 2014 Oct 23.
The aim of this study was to test the hypothesis that running at fixed fractions of Froude (Nfr) and Strouhal (Str) dimensionless numbers combinations induce dynamic similarity between humans of different sizes. Nineteen subjects ran in three experimental conditions, (i) constant speed, (ii) similar speed (Nfr) and (iii) similar speed and similar step frequency (Nfr and Str combination). In addition to anthropometric data, temporal, kinematic and kinetic parameters were assessed at each stage to measure dynamic similarity informed by dimensional scale factors and by the decrease of dimensionless mechanical parameter variability. Over a total of 54 dynamic parameters, dynamic similarity from scale factors was met for 16 (mean r=0.51), 32 (mean r=0.49) and 52 (mean r=0.60) parameters in the first, the second and the third experimental conditions, respectively. The variability of the dimensionless preceding parameters was lower in the third condition than in the others. This study shows that the combination of Nfr and Str, computed from the dimensionless energy ratio at the center of gravity (Modela-r) ensures dynamic similarity between different-sized subjects. The relevance of using similar experimental conditions to compare mechanical dimensionless parameters is also proved and will highlight the study of running techniques, or equipment, and will allow the identification of abnormal and pathogenic running patterns. Modela-r may be adapted to study other abilities requiring bounces in human or animal locomotion or to conduct investigations in comparative biomechanics.
以弗劳德（Nfr）和斯特劳哈尔（Str）无量纲数组合的固定分数跑步，可在不同体型的人类之间诱导出动态相似性。19名受试者在三种实验条件下跑步，（i）恒定速度，（ii）相似速度（Nfr），以及（iii）相似速度和相似步频（Nfr和Str组合）。除人体测量数据外，在每个阶段还评估了时间、运动学和动力学参数，以通过尺寸比例因子和无量纲力学参数变异性的降低来衡量动态相似性。在总共54个动态参数中，在第一、第二和第三实验条件下，分别有16个（平均r = 0.51）、32个（平均r = 0.49）和52个（平均r = 0.60）参数满足比例因子的动态相似性。在第三种条件下，无量纲先前参数的变异性低于其他条件。本研究表明，根据重心处的无量纲能量比（Modela-r）计算得出的Nfr和Str的组合可确保不同体型受试者之间的动态相似性。使用相似实验条件来比较力学无量纲参数的相关性也得到了证明，这将突出跑步技术或设备的研究，并有助于识别异常和致病的跑步模式。Modela-r可适用于研究人类或动物运动中其他需要弹跳的能力，或进行比较生物力学研究。
