DETECTION OF SUBMAXIMAL EFFORT IN ISOMETRIC AND ISOKINETIC KNEE EXTENSION TESTS

The use of torque variability and slope measures to detect submaximal efforts has been studied in isometric tests, but not fully investigate d in isokinetic tests. The purpose of this study was to investigate di fferences between maximal and submaximal efforts in isometric and isok inetic knee extension using torque variability and slope measures obta ined from 32 volunteers (age = 25.2 +/- 4.1 years). The coefficient of variation of average torque, coefficient of variation of peak torque, and slope to peak torque were obtained from maximal and submaximal to rque curves during isometric and two isokinetic tests (60 degrees/sec and 180 degrees/sec). Significant differences between effort levels (m aximal and submaximal) were shown for all variables in isometric and i sokinetic tests. An optimized cut-off value to determine submaximal ef forts without false positives was determined for each variable. The co efficient of variation of average torque detected 75% of submaximal ef forts at 180 degrees/sec and slope to peak torque detected 63% of subm aximal efforts at 60 degrees/sec. For both speeds, combining the coeff icient of variation of average torque with slope improved the submaxim al detection rate to 84%. No variable provided a satisfactory detectio n rate for the isometric test. Therefore, submaximal isokinetic knee e xtensions are detectable with torque variability and slope measures, b ut submaximal isometric exercise is not detectable.