Abstract
The purpose of this study was to establish the reliability of isometric and isokinetic torque measurements of the knee extensors in healthy volunteers assessed on the Quadriceps Dynamometer. The subjects (18 men, 16 women) were tested on three occasions, at 1-week intervals, with three different angular velocities (0, 45, and 90 deg/sec). The mean absolute torque values (range 103–206 Nm) and coefficients of variation (range 15–24%) of the knee extensors were comparable with data obtained by other investigators using a Cybex II. Interindividual variability was considerable (13–20%), as had been expected. The maximum intraindividual variability was 11%. An analysis of variance showed substantial differences within the subjects on subsequent weeks and at the different testing speeds. These results suggest that a variability of about 10% is accounted for by individual changes in torque within healthy subjects. It is to be expected that intra individual variability will be greater for patients than for healthy subjects. These data can therefore be relevant for patients in determining the reliability of strength measurements in neuromuscular disorders or in strength training.