Contact time ($t_c$) relies upon the accuracy of foot-strike and toe-off events, for which ground reaction force (GRF) is the gold standard. However, force plates are not always available, e.g., when running on a noninstrumented treadmill. In this situation, a kinematic algorithm (KA) – an algorithm based on motion capture data – might be used if it performs equally for all foot-strike angles across speeds. The purpose of this study was to propose a novel KA, using a combination of heel and toe kinematics (three markers per foot), to detect foot-strike and toe-off and compare it to GRF at different speeds and across foot-strike angles. One hundred runners ran at 9 km/h, 11 km/h, and 13 km/h. Force data and whole-body kinematic data were acquired by an instrumented treadmill and optoelectronic system. Foot-strike and toe-off showed small systematic biases between GRF and KA at all speeds (≤5 ms), except toe-off at 11 km/h (no bias). The root mean square error (RMSE) was ≤9 ms and was mostly constant across foot-strike angles for toe-off (7.4 ms) but not for foot-strike (4.1–11.1 ms). Small systematic biases (≤8 ms) and significant differences (P ≤ 0.01) were reported for $t_c$ at all speeds, and the RMSE was ≤14 ms (≤5%). The RMSE for $t_c$ increased with increasing foot-strike angle (3.5–5.4%). Nonetheless, this novel KA computed smaller errors than existing methods for foot-strike, toe-off, and $t_c$. Therefore, this study supports the use of this novel KA to accurately estimate foot-strike, toe-off, and $t_c$ from kinematic data obtained during noninstrumented treadmill running independent of the foot-strike angle.

联系时间（${吨}_C$) 依赖于足部撞击和脚趾离地事件的准确性，地面反作用力 (GRF) 是黄金标准。然而，测力台并不总是可用的，例如，在非器械跑步机上跑步时。在这种情况下，如果运动学算法 (KA) 是一种基于运动捕捉数据的算法，则可以使用它，前提是它对跨速度的所有足部撞击角度的表现都相同。本研究的目的是提出一种新颖的 KA，结合使用足跟和足尖运动学（每只脚三个标记）来检测足部着地和足尖离地，并将其与不同速度和跨足部着地角度的 GRF 进行比较. 一百名跑步者以 9 公里/小时、11 公里/小时和 13 公里/小时的速度跑步。力数据和全身运动学数据由仪表化跑步机和光电系统采集。除了 11 公里/小时的脚尖离地（无偏差）外，在所有速度下（≤ 5 毫秒），脚触地和脚尖离地在 GRF 和 KA 之间显示出小的系统偏差。均方根误差 (RMSE) ≤ 9 ms，并且在脚尖离地 (7.4 ms) 的足部撞击角度上大部分是恒定的，但足部撞击 (4.1-11.1 ms) 则不然。小的系统偏差（≤8 ms）和显着差异（P  ≤ 0.01) 被报告为${吨}_C$在所有速度下，RMSE ≤ 14 ms (≤ 5%)。RMSE 为${吨}_C$随着足部撞击角度的增加而增加（3.5-5.4%）。尽管如此，这种新颖的 KA 计算的误差比现有的足部撞击、脚趾离地和${吨}_C$. 因此，本研究支持使用这种新颖的 KA 来准确估计足部着地、脚趾离地和${吨}_C$ 从非仪表跑步机运行期间获得的运动学数据与足部撞击角度无关。