Reliability of Force Production Based on the Sense of Effort at Different Force Levels

Accurate force production based on the sense of effort plays a critical role in daily motor control and clinical assessment; however, the reliability of such force production across different force levels remains insufficiently understood. Establishing reliable measurement conditions is essential for interpreting changes in force production based on the sense of effort in both research and applied settings. In this study, we examined the test-retest reliability of grip-force production based on the sense of effort at three force levels: 25%, 50%, and 75% of the maximum voluntary contraction (MVC). A total of 33 young men performed grip-force tests across two sessions, separated by one week, without external feedback. Relative reliability was evaluated using intraclass correlation coefficients (ICCs), and absolute reliability was assessed using standard error of measurement (SEM) and the 95% minimal detectable change. The highest reliability was observed at 25% MVC, with a tendency toward reduced reliability at 50% MVC. These findings suggest that low-force-level production based on the sense of effort is relatively stable, possibly reflecting its frequent use in daily activities and simpler neural control mechanisms. Therefore, it is suggested that lower force levels enable more reliable measurements when evaluating force production based on the sense of effort