Department of Sport Sciences, Sports Research Centre, Miguel Hernandez University of Elche, Elche, Spain.
UIRFIDE Research Group; Physical Education and Sports Department, Manuel Mateo-March, Spanish Cycling Federation, Madrid, Spain.
Sports Biomech. 2023 Jul;22(7):906-920. doi: 10.1080/14763141.2020.1770323. Epub 2020 Jun 22.
Accelerometers are becoming popular in sport performance, as they are easy to wear, affordable, and usable in the field. Eccentric chainrings have been commercialised to improve pedalling performance, but little is known about their possible effects in the first pedal strokes (PS) of maximal sprint starts. To analyse the effects of the Q-Ring chainring (Q) on pedalling mechanics and performance in the BMX starting hill, 12 Spanish-National-Team BMX athletes performed 3 maximal sprints comparing Q vs No-Q. Time was measured in the first three meters. Acceleration output was registered with a triaxial 6 g accelerometer (200 Hz) in the first four PS. Discrete time, acceleration and statistical parametric mapping (SPM) were used to compare between conditions. Q showed no improvement in performance, despite a force-application time increasing (p = 0.013, ES = 0.39) and a reduction in the dead spot time (p = 0.028, ES = -0.73). Time after the four PS was greater (p = 0.006, ES = 0.63), and 3-m time did not change. Likewise, SPM 1D comparison showed no differences along the four PS. Therefore, accelerometry confirms its potential to evaluate pedalling technique in BMX, where Q-Ring fails to improve the pedalling mechanics in the starting hill.
加速度计在运动表现中越来越受欢迎，因为它们易于佩戴、价格实惠且可在现场使用。偏心链轮已经商业化，以提高骑行性能，但对其在最大冲刺启动的第一脚踏（PS）中可能产生的影响知之甚少。为了分析 Q 形链轮（Q）对 BMX 起动坡蹬踏力学和性能的影响，12 名西班牙国家自行车队运动员进行了 3 次最大冲刺，比较了 Q 和无 Q 的情况。前 3 米的时间进行了测量。在第一四个 PS 中，使用三轴 6g 加速度计（200Hz）记录加速度输出。离散时间、加速度和统计参数映射（SPM）用于比较条件。尽管力作用时间增加（p=0.013，ES=0.39）和死点时间减少（p=0.028，ES=-0.73），但 Q 并未提高性能。PS 后四个时间更大（p=0.006，ES=0.63），3m 时间没有变化。同样，SPM 1D 比较显示在四个 PS 期间没有差异。因此，加速度计证实了其在 BMX 中评估蹬踏技术的潜力，在起动坡中，Q 形链轮未能改善蹬踏力学。
