Malisoux Laurent, Gette Paul, Backes Anne, Delattre Nicolas, Cabri Jan, Theisen Daniel
Department of Population Health, Physical Activity, Sport and Health Research Group, Luxembourg Institute of Health, Luxembourg, Luxembourg.
Department of Population Health, Human Motion, Orthopedics, Sports Medicine and Digital Methods Research Group, Luxembourg Institute of Health, Luxembourg, Luxembourg.
Front Sports Act Living. 2021 Nov 11;3:744658. doi: 10.3389/fspor.2021.744658. eCollection 2021.
Cushioning systems in running shoes are used assuming that ground impact forces relate to injury risk and that cushioning materials reduce these impact forces. In our recent trial, the more cushioned shoe version was associated with lower injury risk. However, vertical impact peak force was higher in participants with the Soft shoe version. The primary objective of this study was to investigate the effect of shoe cushioning on the time, magnitude and frequency characteristics of peak forces using frequency-domain analysis by comparing the two study groups from our recent trial (Hard and Soft shoe group, respectively). The secondary objective was to investigate if force characteristics are prospectively associated with the risk of running-related injury. This is a secondary analysis of a double-blinded randomized trial on shoe cushioning with a biomechanical running analysis at baseline and a 6-month follow-up on running exposure and injury. Participants ( = 848) were tested on an instrumented treadmill at their preferred running speed in their randomly allocated shoe condition. The vertical ground reaction force signal for each stance phase was decomposed into the frequency domain using the discrete Fourier transform. Both components were recomposed into the time domain using the inverse Fourier transform. An analysis of variance was used to compare force characteristics between the two study groups. Cox regression analysis was used to investigate the association between force characteristics and injury risk. Participants using the Soft shoes displayed lower impact peak force ( < 0.001, = 0.23), longer time to peak force ( < 0.001, = 0.25), and lower average loading rate ( < 0.001, = 0.18) of the high frequency signal compared to those using the Hard shoes. Participants with low average and instantaneous loading rate of the high frequency signal had lower injury risk [Sub hazard rate ratio (SHR) = 0.49 and 0.55; 95% Confidence Interval (CI) = 0.25-0.97 and 0.30-0.99, respectively], and those with early occurrence of impact peak force (high frequency signal) had greater injury risk (SHR = 1.60; 95% CI = 1.05-2.53). Our findings may explain the protective effect of the Soft shoe version previously observed. The present study also demonstrates that frequency-domain analyses may provide clinically relevant impact force characteristics. https://clinicaltrials.gov/, identifier: 9NCT03115437.
地面冲击力与受伤风险相关，且缓冲材料能降低这些冲击力。在我们最近的试验中，缓冲性更强的鞋款与更低的受伤风险相关。然而，穿着软质鞋款的参与者垂直冲击峰值力更高。本研究的主要目的是通过比较我们最近试验中的两个研究组（分别为硬质鞋组和软质鞋组），利用频域分析来探究鞋类缓冲对峰值力的时间、大小和频率特征的影响。次要目的是研究力的特征是否与跑步相关损伤的风险存在前瞻性关联。这是一项关于鞋类缓冲的双盲随机试验的二次分析，在基线时进行生物力学跑步分析，并在6个月的随访中记录跑步暴露情况和损伤情况。参与者（ = 848）在配备仪器的跑步机上以其偏好的跑步速度，在随机分配的鞋类条件下进行测试。每个站立阶段的垂直地面反作用力信号使用离散傅里叶变换分解到频域。两个分量使用逆傅里叶变换重新组合到时域。使用方差分析比较两个研究组之间的力特征。使用Cox回归分析研究力特征与损伤风险之间的关联。与穿着硬质鞋的参与者相比，穿着软质鞋的参与者高频信号的冲击峰值力更低（ < 0.001， = 0.23），达到峰值力的时间更长（ < 0.001， = 0.25），平均加载率更低（ < 0.001， = 0.18）。高频信号平均和瞬时加载率低的参与者受伤风险更低[亚风险率比（SHR） = 0.49和0.55；95%置信区间（CI）分别为0.25 - 0.97和0.30 - 0.99]，而冲击峰值力（高频信号）出现较早的参与者受伤风险更高（SHR = 1.60；95% CI = 1.05 - 2.53）。我们的研究结果可能解释了之前观察到的软质鞋款的保护作用。本研究还表明，频域分析可能提供与临床相关的冲击力特征。https://clinicaltrials.gov/，标识符：9NCT03115437 。
