Hanley Brian, Tucker Catherine B, Gallagher Liam, Parelkar Parag, Thomas Liam, Crespo Rubén, Price Rob J
Carnegie School of Sport, Leeds Beckett University, Leeds, United Kingdom.
Leeds United Football Club, Leeds, United Kingdom.
Front Sports Act Living. 2022 Aug 9;4:939676. doi: 10.3389/fspor.2022.939676. eCollection 2022.
English Premier League soccer players run at multiple speeds throughout a game. The aim of this study was to assess how well the duty factor, a dimensionless ratio based on temporal variables, described running styles in professional soccer players. A total of 25 players ran on an instrumented treadmill at 12, 16, and 20 km/h. Spatiotemporal and ground reaction force data were recorded for 30 s at each speed; video data (500 Hz) were collected to determine footstrike patterns. In addition to correlation analysis amongst the 25 players, two groups (both = 9) of high and low duty factors were compared. The duty factor was negatively correlated with peak vertical force, center of mass (CM) vertical displacement, and leg stiffness ( ) at all speeds ( ≥ -0.51, ≤ 0.009). The low duty factor group had shorter contact times, longer flight times, higher peak vertical forces, greater CM vertical displacement, and higher ( < 0.01). Among the high DF group players, eight were rearfoot strikers at all speeds, compared with three in the low group. The duty factor is an effective measure for categorizing soccer players as being on a continuum from terrestrial (high duty factor) to aerial (low duty factor) running styles, which we metaphorically refer to as "grizzlies" and "gazelles," respectively. Because the duty factor distinguishes running style, there are implications for the training regimens of grizzlies and gazelles in soccer, and exercises to improve performance should be developed based on the biomechanical advantages of each spontaneous running style.
英超足球运动员在一场比赛中会以多种速度奔跑。本研究的目的是评估负荷因子（一种基于时间变量的无量纲比率）对职业足球运动员跑步方式的描述程度。共有25名球员在装有仪器的跑步机上以12、16和20公里/小时的速度跑步。每种速度下记录30秒的时空和地面反作用力数据；收集视频数据（500赫兹）以确定触地模式。除了对25名球员进行相关性分析外，还比较了两组（每组均为9人）高负荷因子和低负荷因子的情况。在所有速度下，负荷因子与垂直力峰值、重心（CM）垂直位移和腿部刚度均呈负相关（≥ -0.51，≤ 0.009）。低负荷因子组的接触时间更短、腾空时间更长、垂直力峰值更高、CM垂直位移更大且腿部刚度更高（< 0.01）。在高负荷因子组的球员中，有8人在所有速度下均为后足着地，而低负荷因子组中只有3人。负荷因子是一种有效的指标，可将足球运动员按从地面型（高负荷因子）到空中型（低负荷因子）的连续跑步方式进行分类，我们分别将其形象地称为“灰熊”和“羚羊”。由于负荷因子能区分跑步方式，这对足球中灰熊型和羚羊型球员的训练方案有启示意义，应基于每种自然跑步方式的生物力学优势来制定提高成绩的训练方法。
