Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, 1081 BT Amsterdam, The Netherlands.
Sensors (Basel). 2022 Jan 4;22(1):376. doi: 10.3390/s22010376.
Inertial measurement units (IMUs) fixed to the lower limbs have been reported to provide accurate estimates of stride lengths (SLs) during walking. Due to technical challenges, validation of such estimates in running is generally limited to speeds (well) below 5 m·s. However, athletes sprinting at (sub)maximal effort already surpass 5 m·s after a few strides. The present study aimed to develop and validate IMU-derived SLs during maximal linear overground sprints. Recreational athletes ( = 21) completed two sets of three 35 m sprints executed at 60, 80, and 100% of subjective effort, with an IMU on the instep of each shoe. Reference SLs from start to ~30 m were obtained with a series of video cameras. SLs from IMUs were obtained by double integration of horizontal acceleration with a zero-velocity update, corrected for acceleration artefacts at touch-down of the feet. Peak sprint speeds (mean ± SD) reached at the three levels of effort were 7.02 ± 0.80, 7.65 ± 0.77, and 8.42 ± 0.85 m·s, respectively. Biases (±Limits of Agreement) of SLs obtained from all participants during sprints at 60, 80, and 100% effort were 0.01% (±6.33%), -0.75% (±6.39%), and -2.51% (±8.54%), respectively. In conclusion, in recreational athletes wearing IMUs tightly fixed to their shoes, stride length can be estimated with reasonable accuracy during maximal linear sprint acceleration.
惯性测量单元（IMU）固定在下肢已被报道能提供在行走时步长（SL）的精确估计。由于技术挑战，在跑步中对这些估计的验证通常限于速度（好）低于 5 m·s。然而，运动员以（亚）最大努力冲刺已经在几个步幅后超过 5 m·s。本研究旨在开发和验证最大线性地面冲刺过程中的 IMU 衍生 SL。有经验的运动员（= 21）完成了两组三次 35 m 冲刺，速度分别为 60%、80%和 100%的主观努力，每只鞋的脚背都有一个 IMU。参考 SL 从起点到~30 m 是用一系列视频摄像机获得的。IMU 的 SL 是通过水平加速度的二次积分得到的，带有零速度更新，脚触地时的加速度伪影进行了校正。在三种努力水平下达到的峰值冲刺速度（平均值±SD）分别为 7.02±0.80、7.65±0.77 和 8.42±0.85 m·s。在 60%、80%和 100%努力的所有参与者的冲刺中，SL 的偏差（±协议界限）分别为 0.01%（±6.33%）、-0.75%（±6.39%）和-2.51%（±8.54%）。总之，在穿着 IMU 紧紧固定在鞋子上的有经验的运动员中，在最大线性冲刺加速期间，步长可以用合理的精度来估计。
