Influence of Talocrural Joint Position on the Quadriceps Femoris Muscle Torque Measured with an Isokinetic and EasyForce® Dynamometer in Young Adults

<b>Background</b>: Motor irradiation is a concept in which the muscles of the talocrural joint can influence the torque of the quadriceps femoris muscle. The aims of this study are to compare the effects of three different talocrural joint positions on the torque of the quadriceps femoris muscle and to analyze the differences in torque measurements between two dynamometers. <b>Methods</b>: 33 students from the Faculty of Health Studies at the University of Rijeka participated in the study. The torque of the quadriceps femoris muscle was measured using the Cybex CSMi isokinetic dynamometer and the EasyForce^® hand-held fixed dynamometer. The measurements were performed three times continuously for each talocrural joint position. <b>Results</b>: When measured with the isokinetic dynamometer (<i>p</i> = 0.210) and the EasyForce^® dynamometer (<i>p</i> = 0.925), no significant difference was found in the torque of the quadriceps femoris muscle between the three talocrural joint positions. The dynamometers measured the torque consistently and showed a significant, from very good to excellent correlation of the data (<i>p</i> < 0.001), but did not provide identical results due to constant and proportional differences. <b>Conclusions</b>: There was no significant influence of the three talocrural joint positions on the torque of the quadriceps femoris muscle under isometric contraction conditions without a specific angular velocity. The use of the two dynamometers led to similar but inconsistent results in the measurement of muscle torque. This inconsistency is not only because of the differences between the devices themselves, but also due to fundamental methodological differences in participant stabilization and testing procedures.