Owings Tammy M, Grabiner Mark D
Department of Biomedical Engineering, The Cleveland Clinic Foundation, University of Illinois at Chicago, 901 West Roosevelt Road, Chicago, IL 60608, USA.
J Biomech. 2003 Aug;36(8):1215-8. doi: 10.1016/s0021-9290(03)00108-8.
Variability of step kinematics has been associated with falls by older adults. However, between-study differences with regard to the number of steps used to compute variability have varied by an order of magnitude. If the number of steps used to compute variability is too low there is the potential for a statistically spurious outcome. On the other hand, for subjects with mobility impairments a protocol requiring too many steps to estimate variability imposes an unnecessary burden on the subjects. We have determined the minimum number of steps needed to estimate the variability of spatial and temporal step kinematics. More than 700 steps were collected during level walking on an instrumented treadmill. Accurate estimation of step kinematic variability required at least 400 steps. The increased error in estimating the mean and standard deviations of the step kinematic variables with too few steps can impose an experimental cost with regard to statistical design considerations. The extent to which translation of these results can be made to the variability of spatial and temporal step kinematics collected during over-ground walking awaits further research.
步运动学的变异性与老年人跌倒有关。然而，关于用于计算变异性的步数，不同研究之间的差异相差一个数量级。如果用于计算变异性的步数过低，就有可能出现统计学上的虚假结果。另一方面，对于行动不便的受试者，一个需要太多步数来估计变异性的方案会给受试者带来不必要的负担。我们已经确定了估计空间和时间步运动学变异性所需的最少步数。在装有仪器的跑步机上进行水平行走时收集了700多个步数。准确估计步运动学变异性至少需要400步。步数过少时，估计步运动学变量的均值和标准差时误差增加，这在统计设计方面可能会带来实验成本。这些结果能在多大程度上适用于在地面行走时收集的空间和时间步运动学变异性，还有待进一步研究。
