Detection of Submaximal Effort and Assessment of Stability of the Coefficient of Variation

Abstract

Assessment of sincerity of effort is frequently used in clinical practice. However, the reliability and validity of current assessment methods have not been unequivocally demonstrated. This study focused on the detection of submaximal efforts and determination of the stability of the coefficient of variation (CV) in 20 asymptomatic subjects. The coefficient of variation of peak torque (CVpeak) and coefficient of variation of average torque (CVave) were obtained from maximal and submaximal torque curves during fast isokinetic (180 deg/s) leg extension strength tests. Significant differences between effort levels (maximal and submaximal) were found for CVpeak and CVave on both days of testing (p < .001). On Day 1 of testing, using an optimized 10% CVpeak cutoff resulted in a submaximal effort detection rate of 75% with an overall (maximal and submaximal efforts) correct classification rate of 88%. Correlation coefficients indicated relatively moderate stability using the CVpeak calculated using five trials for both maximal (r = .47, p < ,05) and submaximal (r = .78, p < .001) effort conditions. Findings suggest that use of an increased number of repetitions to calculate the CV may result in more stable measures.