Groupe de Recherche En Sciences Pour l'Ingénieur (GRESPI, EA4301), Université de Reims Champagne Ardenne, Reims, France.
Int J Sports Med. 2013 Nov;34(11):945-9. doi: 10.1055/s-0032-1304639. Epub 2013 May 13.
The aim of this study was to test the validity and the reliability of the G-Cog which is a new BMX powermeter allowing for the measurements of the acceleration on X-Y-Z axis (250 Hz) at the BMX rear wheel. These measurements allow computing lateral, angular, linear acceleration, angular, linear velocity and the distance. Mechanical measurements at submaximal intensities in standardized laboratory conditions and during maximal exercises in the field conditions were performed to analyse the reliability of the G-Cog accelerometers. The performances were evaluated in comparison with an industrial accelerometer and with 2 powermeters, the SRM and PowerTap. Our results in laboratory conditions show that the G-Cog measurements have low value of variation coefficient (CV=2.35%). These results suggest that the G-cog accelerometers measurements are reproducible. The ratio limits of agreement of the rear hub angular velocity differences between the SRM and the G-Cog were 1.010 × ÷ 1.024 (95%CI=0.986-1.034) and between PowerTap and G-Cog were 0.993 × ÷ 1.019 (95%CI=0.974-1.012). In conclusion, our results suggest that the G-Cog angular velocity measurements are valid and reliable compared with SRM and PowerTap and could be used to analyse the kinematics during BMX actual conditions.
本研究旨在测试 G-Cog 的有效性和可靠性，G-Cog 是一种新型的 BMX 功率计，可测量后轮的 X-Y-Z 轴（250 Hz）上的加速度。这些测量值可计算侧向、角向、线性加速度、角速度、线速度和距离。在标准化实验室条件下进行亚最大强度的机械测量和在现场条件下进行最大强度的运动，以分析 G-Cog 加速度计的可靠性。性能评估与工业加速度计和 2 个功率计（SRM 和 PowerTap）进行比较。我们在实验室条件下的结果表明，G-Cog 测量的变异系数（CV=2.35%）值较低。这些结果表明 G-cog 加速度计的测量具有可重复性。SRM 和 G-Cog 后轮毂角速度差异的 G-Cog 比值限差为 1.010×÷1.024（95%CI=0.986-1.034），PowerTap 和 G-Cog 之间的比值限差为 0.993×÷1.019（95%CI=0.974-1.012）。总之，我们的结果表明，与 SRM 和 PowerTap 相比，G-Cog 角速度测量值是有效的和可靠的，并且可用于分析 BMX 实际条件下的运动学。
