Fawver Bradley, Roper Jaimie A, Sarmento Carolina, Hass Chris J
Department of Health, Kinesiology, and Recreation, University of Utah, Salt Lake City, UT, USA.
School of Kinesiology, Auburn University, Auburn, AL, USA.
Hum Mov Sci. 2018 Jun;59:1-11. doi: 10.1016/j.humov.2018.03.006. Epub 2018 Mar 17.
We investigated the impact of initial body position on the displacement and velocity of center of pressure adjustments made during gait initiation. Twenty-nine healthy adults (21 ± 1y) initiated forward gait following six seconds of sustained forward posture based on percentage of their forward maximum voluntary lean (0, 5, 10, 20, 50%). Final center of pressure positions for each trial were back-calculated, as a percentage of maximum voluntary lean, using average anteroposterior constant error to the target during the last second of feedback. Scores were aggregated into percentage bands for analysis: Band 1 = -2-4.99%; Band 2 = 5-8.99%; Band 3 = 9-17.99%; Band 4 = 18-29%; Band 5 = 44-54%. Center of pressure displacement and velocity were evaluated during the decoupling, weight shift, and step initiation phases of gait initiation. Subsequent stepping parameters were also compared. During the decoupling phase, greater posterior displacement was observed in band 5 trials compared to 1, 2, and 3, and greater posterior velocity was found for band 5 compared to 1 and 3. During the weight shift phase, greater resultant displacement was found for band 5 compared to 3 and greater resultant velocity for band 5 compared to 2, 3, and 4. During step initiation, participants produced greater anterior displacement and resultant velocity during band 1, 2, and 3 compared to 5. Participants demonstrated greater swing step length and stance step time during band 5 trials compared to 3. These results suggest that only anterior postural positions greater than 44% of a person's maximum voluntary lean systematically alter spatiotemporal and kinematic indices of forward gait initiation in healthy populations. We discuss the conceptual implications of this work with respect to previous behavioral interventions.
我们研究了初始身体姿势对步态起始过程中压力中心调整的位移和速度的影响。29名健康成年人（21±1岁）在基于其向前最大自主倾斜百分比（0%、5%、10%、20%、50%）的持续向前姿势保持6秒后开始向前步态。使用反馈最后一秒内相对于目标的平均前后恒定误差，将每个试验的最终压力中心位置作为最大自主倾斜的百分比进行反算。分数被汇总到百分比区间进行分析：区间1 = -2 - 4.99%；区间2 = 5 - 8.99%；区间3 = 9 - 17.99%；区间4 = 18 - 29%；区间5 = 44 - 54%。在步态起始的解耦、体重转移和步幅起始阶段评估压力中心的位移和速度。还比较了随后的步幅参数。在解耦阶段，与区间1、2和3相比，区间5试验中观察到更大的向后位移，与区间1和3相比，区间5的向后速度更大。在体重转移阶段，与区间3相比，区间5的合成位移更大，与区间2、3和4相比，区间5的合成速度更大。在步幅起始阶段，与区间·5相比，参与者在区间1、2和3期间产生了更大的向前位移和合成速度。与区间3相比，参与者在区间5试验中表现出更大的摆动步幅长度和站立步幅时间。这些结果表明，只有大于个人最大自主倾斜44%的前位姿势会系统地改变健康人群向前步态起始的时空和运动学指标。我们讨论了这项工作相对于先前行为干预的概念性意义。
