Hanley Brian, Bissas Athanassios, Merlino Stéphane
Carnegie School of Sport, Leeds Beckett University, Leeds, United Kingdom.
School of Sport and Exercise, University of Gloucestershire, Gloucester, United Kingdom.
Front Sports Act Living. 2020 Aug 6;2:102. doi: 10.3389/fspor.2020.00102. eCollection 2020.
World-class marathon runners make initial contact with the rearfoot, midfoot or forefoot. This novel study analyzed kinematic similarities and differences between rearfoot and non-rearfoot strikers within the men's and women's 2017 IAAF World Championship marathons across the last two laps. Twenty-eight men and 28 women, equally divided by footstrike pattern, were recorded at 29.5 and 40 km (laps 3 and 4, respectively) using two high-definition cameras (50 Hz). The videos were digitized to derive spatiotemporal and joint kinematic data, with additional footage (120 Hz) used to identify footstrike patterns. There was no difference in running speed, step length or cadence between rearfoot and non-rearfoot strikers during either lap in both races, and these three key variables decreased in athletes of either footstrike pattern to a similar extent between laps. Men slowed more than women between laps, and overall had greater reductions in step length and cadence. Rearfoot strikers landed with their foot farther in front of the center of mass (by 0.02-0.04 m), with non-rearfoot strikers relying more on flight distance for overall step length. Male rearfoot strikers had more extended knees, dorsiflexed ankles and hyperextended shoulders at initial contact than non-rearfoot strikers, whereas female rearfoot strikers had more flexed hips and extended knees at initial contact. Very few differences were found at midstance and toe-off. Rearfoot and non-rearfoot striking techniques were therefore mostly indistinguishable except at initial contact, and any differences that did occur were very small. The spatiotemporal variables that differed between footstrike patterns were not associated with faster running speeds and, ultimately, neither footstrike pattern prevented reductions in running speeds. The only joint angle measured at a specific gait event to change with fatigue was midswing knee flexion angle in men. Coaches should thus note that encouraging marathon runners to convert from rearfoot to non-rearfoot striking is unlikely to provide any performance benefits, and that training the fatigue resistance of key lower limb muscle-tendon units to avoid decreases in step length and cadence are more useful in preventing reductions in speed during the later stages of the race.
世界级马拉松运动员起跑时后脚、中脚或前脚先着地。这项新研究分析了在2017年国际田联世界锦标赛马拉松比赛的男子和女子组最后两圈中，后脚先着地和非后脚先着地的跑步者之间的运动学异同。按照着地方式将28名男性和28名女性平均分组，在29.5公里和40公里处（分别为第3圈和第4圈）使用两台高清摄像机（50赫兹）进行记录。视频被数字化以获取时空和关节运动学数据，另外还使用了频率为120赫兹的额外视频片段来确定着地方式。在两场比赛的每一圈中，后脚先着地和非后脚先着地的跑步者在跑步速度、步长或步频上均无差异，并且这三个关键变量在两种着地方式的运动员中在两圈之间都有相似程度的下降。男性在两圈之间比女性减速更多，并且总体上步长和步频的下降幅度更大。后脚先着地的跑步者着地时脚在身体重心前方更远的位置（相差0.02 - 0.04米），非后脚先着地的跑步者在总体步长上更多地依赖飞行距离。男性后脚先着地者在初始接触时比非后脚先着地者的膝盖伸展程度更大、脚踝背屈、肩膀过度伸展，而女性后脚先着地者在初始接触时臀部更弯曲、膝盖伸展。在支撑中期和离地时发现的差异非常少。因此，除了初始接触时，后脚先着地和非后脚先着地的技术大多难以区分，并且出现的任何差异都非常小。着地方式之间不同的时空变量与更快的跑步速度无关，最终，两种着地方式都无法阻止跑步速度的下降。在特定步态事件中测量的唯一随疲劳而变化的关节角度是男性摆动中期的膝关节屈曲角度。因此，教练应该注意到，鼓励马拉松运动员从后脚先着地转变为非后脚先着地不太可能带来任何成绩提升，并且训练关键下肢肌肉 - 肌腱单元的抗疲劳能力以避免步长和步频下降，对于防止比赛后期速度下降更有用。
