Sports Research Centre, Department of Sport Sciences, Miguel Hernández University, Elche, Spain.
Department of Education Science, Universidad Cardenal Herrera-CEU, CEU Universities, Castellon de la Plana, Spain.
J Appl Biomech. 2024 Jan 4;40(3):176-182. doi: 10.1123/jab.2023-0020. Print 2024 Jun 1.
Bike fitting aims to optimize riders' positions to improve their performance and reduce the risk of injury. To calculate joint angles, the location of the joint centers of the lower limbs needs to be identified. However, one of the greatest difficulties is the location of the hip joint center due to the frequent occlusion of the anterior superior iliac spine markers. Therefore, the objective of this study was to validate a biomechanical model adapted to cycling (modified pelvic model, MPM), based on the traditional pelvic model (TPM) with an additional lateral technical marker placed on the iliac crests. MPM was also compared with a widely used model in cycling, trochanter model (TM). Thirty-one recreational cyclists pedaled on a roller bike while the movement was captured with a 7-camera VICON system. The position of the hip joint center and knee angle were calculated and compared with the TPM continuously (along 10 pedaling cycles) and discreetly at 90° and 180° crank positions. No significant differences were found in the position of the hip joint center or in the knee flexion/extension angle between the TPM and the MPM. However, there are differences between TPM and TM (variations between 4.1° and 6.9° in favor of the TM at 90° and 180°; P < .001). Bland-Altman graphs comparing the models show an average difference or bias close to 0° (limits of agreement [0.2 to -8.5]) between TPM and MPM in both lower limbs and a mean difference of between -4° and -7° (limits of agreement [-0.6 to -13.2]) when comparing TPM and TM. Given the results, the new cycling pelvic model has proven to be valid compared with the TPM when performing bike fitting studies, with the advantage that the occluded markers are avoided. Despite its simplicity, the TM presents measurement errors that may be relevant when making diagnoses, which makes its usefulness questionable.
自行车适配旨在优化骑手的姿势，以提高他们的表现并降低受伤风险。为了计算关节角度，需要确定下肢关节中心的位置。然而，最大的困难之一是髋关节中心的位置，因为前上髂嵴标志物经常被遮挡。因此，本研究的目的是验证一种基于传统骨盆模型（TPM）的生物力学模型，该模型增加了一个放置在髂嵴上的侧向技术标志物（改良骨盆模型，MPM），并将其与广泛应用于自行车的模型（转子模型，TM）进行比较。31 名休闲自行车手在滚子自行车上骑行，运动过程被 7 个摄像机的 VICON 系统捕获。计算髋关节中心位置和膝关节角度，并与 TPM 连续（沿 10 个踩踏周期）和离散（在 90°和 180°曲柄位置）进行比较。在髋关节中心位置或膝关节屈伸角度方面，TPM 和 MPM 之间没有发现显著差异。然而，TPM 和 TM 之间存在差异（在 90°和 180°时，TM 分别有利于 TM 的角度变化为 4.1°和 6.9°；P<.001）。比较模型的 Bland-Altman 图显示，在左右下肢中，TPM 和 MPM 之间的平均差异或偏差接近 0°（一致性区间为[0.2 到-8.5]），而在 TPM 和 TM 之间的平均差异在-4°和-7°之间（一致性区间为[-0.6 到-13.2]）。鉴于这些结果，新的自行车骨盆模型在进行自行车适配研究时已被证明与 TPM 相比是有效的，并且避免了被遮挡的标志物。尽管 TM 很简单，但它存在测量误差，在进行诊断时可能很重要，这使得其有用性值得怀疑。
