Fishbain D A, Abdel-Moty E, Cutler R B, Rosomoff H L, Steele-Rosomoff R
Department of Psychiatry, University of Miami School of Medicine, and the Comprehensive Pain and Rehabilitation Center at South Shore Hospital, Miami Beach, Florida 33139, USA.
Am J Phys Med Rehabil. 1999 May-Jun;78(3):222-7. doi: 10.1097/00002060-199905000-00007.
The objective of this study was to develop an experimental method to separate a "faked" strength effort from a "best" effort in volunteers. Thirty-four pain-free volunteers (18 males, 16 females) performed a shoulder press and pull-down on an isokinetic computerized exercise testing system (CETS), giving a best effort followed by a faked effort. Two months later, a randomly selected subgroup (6 males) repeated the experiment to test the predictive validity of the derived variables. In the statistical analysis, best efforts were first compared with fake efforts by paired ttest for 80 CETS variables for males and females separately. Variables showing a strong difference between the best and faked effort were then selected for further analysis. In the second step of the analysis, the method of multiple correlations (r2 method) was used to reduce the number of redundant CETS variables to five in both the male and female groups. In the third step, a stepwise discriminant analysis was used to select predictor variables for the male and female groups. For the variables selected by the discriminant analysis for both males and females, sensitivities and specificities were calculated. Finally, the developed discriminant formula was used in the predictive validity part of the study to determine the sensitivities and specificities of the developed method. The discriminant analysis selected the following CETS variables for male and female groups, respectively: duty cycle down, work weight/down, peak value up (males); and average power up, 40% repetition down, duty cycle up (females). For males, using their three variables, the discriminant function classified 77.14% of the efforts correctly with 88.9% sensitivity and 64.7% specificity. For females, using their three variables, the discriminant function classified 90.63% of the efforts correctly with 100% sensitivity and 81.3% specificity. In the predictive validity group, the discriminant function classified 75% of the efforts correctly with 83.3% sensitivity and 66.7% specificity. This pilot study indicates that the method developed here may be useful in the experimental study for the discrimination between faked and best efforts on this isokinetic CETS machine. Future studies using this method will need to involve a larger number of volunteers.
本研究的目的是开发一种实验方法，以区分志愿者的“虚假”用力和“最佳”用力。34名无疼痛志愿者（18名男性，16名女性）在等速计算机化运动测试系统（CETS）上进行了坐姿推举和下拉动作，先进行一次最佳用力，然后进行一次虚假用力。两个月后，一个随机抽取的亚组（6名男性）重复该实验，以检验所推导变量的预测效度。在统计分析中，首先通过配对t检验分别对男性和女性的80个CETS变量的最佳用力和虚假用力进行比较。然后选择在最佳用力和虚假用力之间显示出强烈差异的变量进行进一步分析。在分析的第二步中，使用多重相关方法（r2方法）将男性和女性组中冗余的CETS变量数量减少到5个。在第三步中，使用逐步判别分析为男性和女性组选择预测变量。对于判别分析为男性和女性选择的变量，计算敏感性和特异性。最后，在研究的预测效度部分使用所开发的判别公式来确定所开发方法的敏感性和特异性。判别分析分别为男性和女性组选择了以下CETS变量：下拉占空比、下拉工作重量、上峰值（男性）；以及上平均功率、40%重复下拉、上占空比（女性）。对于男性，使用他们的三个变量，判别函数正确分类了77.14%的用力，敏感性为88.9%，特异性为64.7%。对于女性，使用她们的三个变量，判别函数正确分类了90.63%的用力，敏感性为100%，特异性为81.3%。在预测效度组中，判别函数正确分类了75%的用力，敏感性为83.3%，特异性为66.7%。这项初步研究表明，这里开发的方法可能有助于在该等速CETS机器上进行区分虚假用力和最佳用力的实验研究。未来使用该方法的研究将需要纳入更多数量的志愿者。
