Indiana University School of Medicine, Department of Physical Medicine and Rehabilitation, Indianapolis, IN, USA; Rehabilitation Hospital of Indiana, Indianapolis, IN, USA.
Indiana University School of Medicine, Department of Physical Medicine and Rehabilitation, Indianapolis, IN, USA; Rehabilitation Hospital of Indiana, Indianapolis, IN, USA.
J Biomech. 2020 Feb 13;100:109602. doi: 10.1016/j.jbiomech.2020.109602. Epub 2020 Jan 3.
Improvements in gait speed following various training paradigms applied to patients post-stroke does not always lead to changes in walking performance, defined as gains in daily stepping activity. We hypothesized that testing conditions, specifically the presence of an observer, influences patient behaviors and resultant outcomes may overestimate their true walking capacity. This potential Hawthorne effect on spatiotemporal and biomechanical measures of locomotor function in individuals post-stroke has not been assessed previously. Fifteen ambulatory individuals with chronic stroke wore instrumented insoles and performed two separate normal-pace walking assessments, including unobserved conditions during which participants were unattended and unaware of data collection, and observed conditions with an investigator present. Gait analysis was conducted outside of a laboratory setting using instrumented insoles equipped with a 3D accelerometer and pressure sensors which captured the spatiotemporal kinematics, vertical ground reaction forces and foot acceleration. Data were compared using paired comparisons, with subsequent correlation and stepwise regression analyses to explore potential associations between Hawthorne-induced changes in walking strategies, gait speed and locomotor performance (daily stepping). Except for cadence, other measures of spatiotemporal parameters and swing kinematics (acceleration) were not significantly different between observed vs unobserved conditions. However, analyses of ground reaction forces revealed significantly greater paretic limb loading (Δ1 peak = 1.5 ± 1.6 N/kg Δ2 peak = 1.4 ± 1.8 N/kg; p < 0.01) and increases in weight bearing symmetry (11-24%, p < 0.01) during observed vs unobserved conditions. This potential Hawthorne effect was greater in those with slower walking speeds and shorter stride lengths but was not related to daily stepping. The present findings suggest that biomechanical parameters of walking function may be related to the presence of an observer and highlight the need to separately measure locomotor capacity (gait speed) and performance (daily stepping).
在各种针对脑卒中患者的训练模式下，步态速度的改善并不总是导致行走表现的变化，定义为日常跨步活动的增加。我们假设测试条件，特别是观察者的存在，会影响患者的行为，导致结果可能高估了他们的真实行走能力。这种潜在的霍桑效应在脑卒中后个体的运动功能时空和生物力学测量中尚未得到评估。15 名慢性脑卒中患者佩戴了仪器化鞋垫，并进行了两次单独的正常步速行走评估，包括无人观察的条件（参与者无人照顾且不知道正在进行数据收集）和有观察者在场的条件。步态分析是在实验室环境之外进行的，使用配备了 3D 加速度计和压力传感器的仪器化鞋垫，这些传感器可以捕捉时空运动学、垂直地面反作用力和脚部加速度。使用配对比较比较数据，随后进行相关和逐步回归分析，以探讨观察引起的行走策略、步态速度和运动表现（日常跨步）变化之间的潜在关联。除了步频外，时空参数和摆动运动学（加速度）的其他测量值在观察条件与无人观察条件之间没有显著差异。然而，地面反作用力分析显示，在观察条件下，患侧肢体的负荷明显增加（Δ1 峰值=1.5±1.6N/kg，Δ2 峰值=1.4±1.8N/kg；p<0.01），承重对称性增加（11-24%，p<0.01）。这种潜在的霍桑效应在行走速度较慢和步长较短的患者中更大，但与日常跨步无关。目前的发现表明，行走功能的生物力学参数可能与观察者的存在有关，并强调需要分别测量运动能力（步态速度）和表现（日常跨步）。
