Schwartz Michael H
Gillette Children's Specialty Healthcare, Center for Gait and Motion Analysis, St. Paul, MN 55101, USA.
Gait Posture. 2007 Oct;26(4):494-500. doi: 10.1016/j.gaitpost.2007.07.014. Epub 2007 Sep 12.
There are concerns that experimental imprecision of measured oxygen cost reduces its clinical utility. These concerns are exacerbated when net energy (walking-resting) is assessed. Therefore, the variability of net oxygen cost should be carefully evaluated, including an exploration of the potential for protocol changes to improve the measure's reliability. In this study a retrospective analysis was used to compare the variability in net oxygen cost between two protocols at a single center. Two groups of subjects (protocols) were analyzed. The subjects in each group met the following criteria: (i) diagnosis of cerebral palsy, (ii) no prior surgery, and (iii) oxygen cost data collected while walking barefoot. The protocols differed in terms of subject preparation, duration of the resting period, and the method used for determining both resting and walking steady state. The net non-dimensional oxygen cost versus dimensionless speed showed essentially identical quadratic regression fits for the two groups, suggesting that the samples were well matched, and the protocols were unbiased. The variability, as measured by mean square error, showed an approximately five-fold reduction with respect to the regression (MSE(old)=.262, MSE(new)=.050), indicating a significant decrease in experimental errors. Further analysis is warranted to determine the primary sources of error reduction, and to further optimize the testing protocol.
有人担心所测量的氧气消耗的实验不精确性会降低其临床效用。当评估净能量（行走 - 休息）时，这些担忧会加剧。因此，应仔细评估净氧气消耗的变异性，包括探索方案改变以提高测量可靠性的可能性。在本研究中，采用回顾性分析来比较单一中心两种方案之间净氧气消耗的变异性。分析了两组受试者（方案）。每组中的受试者符合以下标准：（i）脑瘫诊断，（ii）无既往手术史，以及（iii）赤脚行走时收集的氧气消耗数据。两种方案在受试者准备、休息期持续时间以及确定休息和行走稳态所使用的方法方面有所不同。两组的净无量纲氧气消耗与无量纲速度显示出基本相同的二次回归拟合，表明样本匹配良好，且方案无偏差。以均方误差衡量的变异性相对于回归显示出约五倍的降低（MSE（旧） = 0.262，MSE（新） = 0.050），表明实验误差显著降低。有必要进行进一步分析以确定误差降低的主要来源，并进一步优化测试方案。
