Hanley Brian, Tucker Catherine B, Bissas Athanassios
Carnegie School of Sport, Leeds Beckett University, Leeds, United Kingdom.
Front Sports Act Living. 2019 Aug 8;1:9. doi: 10.3389/fspor.2019.00009. eCollection 2019.
IAAF Rule 230.2 states that racewalkers must have no visible (to the human eye) loss of contact with the ground and that their advancing leg must be straightened from first contact with the ground until the "vertical upright position." The aims of this study were first to analyze racewalking judges' accuracy in assessing technique and, second, to measure flight times across a range of speeds to establish when athletes were likely to lose visible contact. Twenty racewalkers were recorded in a laboratory using a panning video camera (50 Hz), a high-speed camera (100 Hz), and three force plates (1,000 Hz). Eighty-three judges of different IAAF Levels (and none) viewed the panned videos online and indicated whether each athlete was racewalking legally. Flight times shorter than 0.033 s were detected by fewer than 12.5% of judges, and thus indicated non-visible loss of contact. Flight times between 0.040 and 0.045 s were usually detected by no more than three out of eight judges. Very long flight times (≥0.060 s) were detected by nearly all judges. The results also showed that what judges generally considered straightened knees (>177°) was close to a geometrically straight line. Within this inexact definition, IAAF World Championship-standard Level III judges were most accurate, being more likely to detect anatomically bent knees and less likely to indicate bent knees when they did not occur. For the second part, the men racewalked down a 45-m indoor track at 11, 12, 13, 14, and 15 km/h in a randomized order, whereas the women's trials were at 10, 11, 12, 13, and 14 km/h. Flight times, measured using an OptoJump Next photocell system (1,000 Hz), increased for the men from 0.015 s at 11 km/h to 0.040 s at 14 km/h and 0.044 s at 15 km/h, and for the women from 0.013 s at 10 km/h to 0.041 s at 13 km/h and 0.050 s at 14 km/h. For judging by the human eye, the threshold for avoiding visible loss of contact therefore occurred for most athletes at ~14 km/h for men and 13 km/h for women.
国际田联规则230.2规定，竞走运动员与地面接触的情况必须肉眼不可见，且其前腿从首次接触地面到“垂直直立位置”必须伸直。本研究的目的一是分析竞走裁判评估技术的准确性，二是测量一系列速度下的腾空时间，以确定运动员何时可能出现肉眼可见的离地情况。在实验室中，使用平移摄像机（50赫兹）、高速摄像机（100赫兹）和三个测力板（1000赫兹）对20名竞走运动员进行了记录。83名不同国际田联级别的裁判（以及非裁判人员）在线观看了平移视频，并指出每名运动员的竞走是否合规。腾空时间短于0.033秒的情况，只有不到12.5%的裁判能检测到，因此这表明存在肉眼不可见的离地情况。0.040至0.045秒之间的腾空时间，通常在8名裁判中最多只有3人能检测到。几乎所有裁判都能检测到非常长的腾空时间（≥0.060秒）。结果还表明，裁判通常认为膝盖伸直（>177°）接近几何直线。在这个不精确的定义范围内，国际田联世界锦标赛标准的三级裁判最为准确，他们更有可能检测到解剖学意义上弯曲的膝盖，而在膝盖未弯曲时判定弯曲的可能性较小。对于第二部分，男性竞走运动员以随机顺序在45米的室内跑道上分别以11、12、13、14和15公里/小时的速度行走，而女性运动员的测试速度为10、11、12、13和14公里/小时。使用OptoJump Next光电管系统（1000赫兹）测量的腾空时间，男性从11公里/小时时的0.015秒增加到14公里/小时时的0.040秒和15公里/小时时的0.044秒，女性从10公里/小时时的0.013秒增加到13公里/小时时的0.041秒和14公里/小时时的0.050秒。因此，对于肉眼判断来说，大多数运动员避免肉眼可见离地情况的速度阈值，男性约为14公里/小时，女性约为13公里/小时。
