Department of Clinical and Health Psychology, University of Florida, USA.
J Occup Rehabil. 1993 Mar;3(1):45-50. doi: 10.1007/BF01076741.
The use of the coefficient of variation (CV) to determine level of effort in grip strength testing was examined empirically. Twenty-nine asymptomatic subjects participated in two conditions of testing: 100% effort and 50% effort. Order of conditions was counterbalanced and each subject was run in both conditions twice in the same order in order to assess the stability of the method. The number of trials (grasps) per condition was three for a total of 12 grasps for the study. The submaximal (50%) effort condition showed significantly more variability than the maximal effort condition in both sets of conditions (p<.01). Intra-class correlation coefficients were very low for both maximal effort and submaximal efforts (.036 and .025) indicating very low stability for the coefficient of variation. Classification rates were also found to have unacceptably large errors with 69% of the submaximal efforts being classified as maximal with the traditional 15% CV cutoff and 55% misclassification of submaximal efforts with an optimized 11% CV cutoff. It was concluded that the currently practiced method of using a low number of repetitions to calculate the CV may result in very unstable measures. Furthermore the "false negative" rate in using this method is unacceptably high for practical application. The implications of using the method and suggestions for improvement are discussed.
使用变异系数（CV）来确定握力测试中的努力程度在经验上进行了检验。29 名无症状受试者参与了两种测试条件：100%的努力和 50%的努力。测试条件的顺序是平衡的，每个受试者以相同的顺序在两种条件下各进行两次测试，以评估该方法的稳定性。每种条件下的测试次数（抓握）为 3 次，总共有 12 次抓握用于研究。在两组条件下，亚最大（50%）努力条件的变异性明显大于最大努力条件（p<.01）。最大努力和次最大努力的组内相关系数都非常低（.036 和.025），表明变异系数的稳定性非常低。分类率也发现存在不可接受的大误差，69%的次最大努力被归类为最大努力，传统的 15%CV 截止值有 55%的次最大努力分类错误，优化的 11%CV 截止值。因此得出结论，目前使用低重复次数计算 CV 的方法可能会导致非常不稳定的测量。此外，这种方法的“假阴性”率对于实际应用来说是不可接受的高。讨论了使用该方法的影响和改进建议。
