Hanley Brian, Tucker Catherine B, Bissas Athanassios
a Carnegie School of Sport, Headingley Campus , Leeds Beckett University , Leeds , UK.
J Sports Sci. 2018 Jun;36(11):1250-1255. doi: 10.1080/02640414.2017.1372928. Epub 2017 Aug 29.
Race walking is an event where the knee must be straightened from first contact with the ground until midstance. The aim of this study was to compare knee angle measurements between 2D videography and 3D optoelectronic systems. Passive retroreflective markers were placed on the right leg of 12 race walkers and 3D marker coordinate data captured (250 Hz), with 2D video data (100 Hz) recorded simultaneously. Knee angle data were first derived based on the markers' coordinates, and separately by using a 3D model that also incorporated thigh and shank clusters; the video data were analysed using both automatic tracking and manual digitising, creating four conditions overall. Differences were calculated between conditions for stance (using root mean square values), and at discrete events. There were few differences between systems, although the 3D model produced larger angles at midstance than using automatic tracking and marker coordinates (by 3 - 6°, P < 0.05). These differences might have occurred because of how the 3D model locates the hip joint, and because of the addition of marker clusters. 2D videography gave similar results to the 3D model when using manual digitising, as it allowed for errors caused by skin movement to be corrected.
竞走是一项从膝盖首次接触地面到身体重心移至支撑腿垂直上方的过程中，膝盖必须保持伸直的运动项目。本研究旨在比较二维摄像技术和三维光电系统在测量膝盖角度方面的差异。在12名竞走运动员的右腿上放置了被动反光标记，并以250赫兹的频率采集三维标记坐标数据，同时以100赫兹的频率记录二维视频数据。膝盖角度数据首先根据标记的坐标得出，另外还通过使用一个包含大腿和小腿群组的三维模型得出；视频数据通过自动跟踪和手动数字化两种方式进行分析，总共产生了四种情况。计算了不同情况下站立阶段（使用均方根值）以及离散事件时的差异。不同系统之间的差异很小，不过三维模型在身体重心移至支撑腿垂直上方时产生的角度比自动跟踪和标记坐标得出的角度更大（大3至6度，P < 0.05）。这些差异可能是由于三维模型确定髋关节位置的方式以及标记群组的添加所致。当使用手动数字化时，二维摄像技术得出的结果与三维模型相似，因为它能够校正皮肤移动所导致的误差。
