Test-Retest Reliability of Isokinetic Knee Extension and Flexion

Abstract

Sole G, Hamrén J, Milosavljevic S, Nicholson H, Sullivan SJ. Test-retest reliability of isokinetic knee extension and flexion. Objective To assess reliability of isokinetic peak torque and work for knee flexion and extension. Design Single-group test-retest. Setting University laboratory. Participants Eleven men and 7 women (mean age, 21y). Interventions Not applicable. Main Outcome Measure Peak torque and work for concentric and eccentric knee extension and flexion were recorded at 60°/s for 3 trials on 2 occasions. Intraclass correlation coefficient model 3,1 (ICC 3,1), standard error (SE) of measurements, and smallest real differences were calculated for the maximum and for the mean peak torque and work of the 3 repetitions. Results Relative reliability was “very high” for peak torque and work (ICC range, >.90). The SE measurements ranged between 5% and 10% of the initial values for both peak torque and work. The smallest change that indicates a real improvement for a single subject (smallest real differences) ranged from 12% to 25% for peak torque and work variables and from 25% to 30% for the peak torque ratios. Conclusions Isokinetic concentric and eccentric knee extensor and flexor strength variables are reliable when measured by the same examiner in asymptomatic subjects.