Structure and Motion Laboratory, Royal Veterinary College, London, UK.
J Biomech. 2009 Nov 13;42(15):2569-74. doi: 10.1016/j.jbiomech.2009.07.024. Epub 2009 Aug 15.
Consistent measurement of maximum running speed overground is problematic due to the difficulty in precise, continual measurement of speed, and the substantial workload in accelerating the body promoting the onset of fatigue. Treadmills remove the requirement for acceleration which enables more repeats. They also allow experiments to be carried out in controlled environments and where space is limited, but they usually depend on manual and subjective speed control. Here we used a draw-wire position sensor and a proportional-derivative (PD) controller to automatically adjust treadmill belt speed of a large equine treadmill. The feedback loop took the real-time position and velocity of the runner relative to the front of the treadmill as input. This control system allowed runners to accelerate from walking speed to a peak running speed within a few strides and then decelerate as quickly as they wished. We used the system to evaluate the variation in maximum speed determination that results from one trial to 10 trials, in eleven individuals. Three trials gave a maximum speed 97.8% of that achieved after ten. The approach used is appropriate for any treadmill where the running zone length is greater than three metres and the speed controller can be externally controlled. Subjects ran 11.5% faster on the treadmill than overground, part of which can be explained by the removal of aerodynamic drag and the fatigue of overground running. Additional factors may, however, contribute to athletes running faster on a treadmill, for instance some aspect of stability or control.
由于精确、连续测量速度的困难以及使身体加速促进疲劳产生的大量工作负荷，在地面上一致地测量最大跑步速度是有问题的。跑步机消除了对加速的需求，从而可以进行更多的重复。它们还允许在受控环境中进行实验，并且在空间有限的情况下进行实验，但它们通常依赖于手动和主观的速度控制。在这里，我们使用拉线位置传感器和比例-微分（PD）控制器来自动调整大型马用跑步机的履带速度。反馈回路将跑步者相对于跑步机前端的实时位置和速度作为输入。该控制系统允许跑步者在几步之内从步行速度加速到最高跑步速度，然后根据自己的意愿尽快减速。我们使用该系统评估了在 11 个人中，从一次试验到十次试验，最大速度确定的变化。三次试验的最大速度达到了十次试验的 97.8%。该方法适用于跑步区域长度大于三米且速度控制器可以外部控制的任何跑步机。与在地面上相比，受试者在跑步机上的速度快了 11.5%，其中一部分原因是消除了空气动力阻力和在地面上跑步的疲劳。然而，其他因素可能会导致运动员在跑步机上跑得更快，例如稳定性或控制的某些方面。
