Kent Jenny A, Stergiou Nicholas, Wurdeman Shane R
Biomechanics Research Building, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE 68182-0860, USA.
Biomechanics Research Building, University of Nebraska at Omaha, 6160 University Drive, Omaha, NE 68182-0860, USA; College of Public Health, 984355 University of Nebraska Medical Center, Omaha, NE 68198-4355, USA.
Clin Biomech (Bristol). 2015 Dec;30(10):1225-9. doi: 10.1016/j.clinbiomech.2015.07.015. Epub 2015 Aug 8.
Variability occurs naturally from stride to stride in healthy gait. It has been shown that individuals with lower limb loss have significantly increased stride-to-stride fluctuations during walking. This is considered indicative of movement disorganization and is associated with less healthy movement. Given that lower limb prosthesis users perform on average less physical activity than able bodied individuals, the purpose of this study was to determine whether increased fluctuations also correspond to a reduced level of activity in daily life.
Twenty-two transtibial amputees wore an activity monitor (Actigraph, Pensacola, FL, USA) for 3 weeks. Lower limb kinematics during treadmill walking were measured using a 12-camera motion capture system. The largest Lyapunov exponent (λ) was calculated bilaterally at the ankle, knee and hip to quantify the stride-to-stride fluctuations of the lower limb joints. Pearson correlations were used to identify the relationships between the average daily step count over the 3 week collection period and λ.
Significant, moderate negative correlations between daily step count and λ were found at the intact ankle (r=0.57, P=0.005), and the knee on the affected side (r=0.44, P=0.038). No such correlation was found at any other lower limb joint.
The negative correlation evident at these two joints demonstrates that increased stride-to-stride fluctuations are related to decreased activity levels, however it remains unclear whether these changes in the stride-to-stride fluctuations promote decreased activity or whether less active individuals do not gain sufficient motor learning experience to achieve a skilled movement.
在健康步态中，步幅之间自然会出现变异性。研究表明，下肢缺失的个体在行走过程中步幅间的波动显著增加。这被认为是运动紊乱的表现，且与不太健康的运动相关。鉴于下肢假肢使用者的平均身体活动量低于健全个体，本研究的目的是确定步幅波动增加是否也对应着日常生活活动水平的降低。
22名经胫骨截肢者佩戴活动监测器（美国佛罗里达州彭萨科拉市的Actigraph）3周。使用12台摄像机的运动捕捉系统测量跑步机行走过程中的下肢运动学。在双侧踝关节、膝关节和髋关节处计算最大Lyapunov指数（λ），以量化下肢关节的步幅间波动。使用Pearson相关性分析来确定3周收集期内的平均每日步数与λ之间的关系。
在健侧踝关节（r = 0.57，P = 0.005）和患侧膝关节（r = 0.44，P = 0.038）处，每日步数与λ之间存在显著的中度负相关。在其他任何下肢关节处均未发现此类相关性。
这两个关节处明显的负相关表明步幅间波动增加与活动水平降低有关，然而，步幅间波动的这些变化是促进了活动水平降低，还是活动较少的个体没有获得足够的运动学习经验以实现熟练运动，目前尚不清楚。
