Abstract：
A fatigue-failure process is hypothesized to govern the development of tibial stress fractures, where bone damage is highly dependent on the peak strain magnitude. To date, much of the work examining tibial strain during running has ignored uphill and downhill running despite the prevalence of this terrain. This study examined the sensitivity of tibial strain to changes in running grade and speed using a combined musculoskeletal-finite element modelling routine. Seventeen participants ran on a treadmill at ±10, ±5 and 0 deg; at each grade, participants ran at 3.33 m s-1 and at a grade-adjusted speed of 2.50 and 4.17 m s-1 for uphill and downhill grades, respectively. Force and motion data were recorded in each grade and speed combination. Muscle and joint contact forces were estimated using inverse-dynamics-based static optimization. These forces were applied to a participant-adjusted finite element model of the tibia. None of the strain variables (50th and 95th percentile strain and strained volume ≥4000 με) differed as a function of running grade; however, all strain variables were sensitive to running speed (F1≥9.59, P≤0.03). In particular, a 1 m s-1 increase in speed resulted in a 9% (∼260 με) and 155% (∼600 mm3) increase in peak strain and strained volume, respectively. Overall, these findings suggest that faster running speeds, but not changes in running grade, may be more deleterious to the tibia.
摘要：
假设疲劳破坏过程可以控制胫骨应力性骨折的发展，其中骨损伤高度依赖于峰值应变大小。迄今为止,尽管这种地形很普遍，但在跑步过程中检查胫骨应变的许多工作都忽略了上坡和下坡跑步。这项研究使用组合的肌肉骨骼-有限元建模程序检查了胫骨应变对跑步等级和速度变化的敏感性。17名参与者在±10°的跑步机上跑步，±5°,和0°；在每个等级，参与者以3.33ms-1的速度跑步，上坡和下坡的坡度调整速度-2.50和4.17ms-1，分别。在每个等级和速度组合中记录力和运动数据。使用基于逆动力学的静态优化来估计肌肉和关节接触力。这些力被施加到胫骨的参与者调整的有限元模型。没有应变变量（第50和第95百分位应变和应变体积≥4000μ²）作为运行等级的函数而有所不同；但是，所有应变变量对运行速度敏感（F≥9.59，p≤0.03）。特别是,速度增加1ms-1导致峰值应变和应变体积增加9％（≈260μ²）和155％（≈600mm3），分别。总的来说,这些发现表明，更快的跑步速度，但运行等级没有变化，可能对胫骨更有害.•与应力骨折发展有关的高幅度胫骨应变对运行速度的变化敏感，但对等级不敏感。•胫骨应变测量的大部分差异是由个体受试者差异造成的，加强固有肌肉骨骼特性在确定骨骼应变环境中的重要性。
