Modifying the Meaning of the Upper Anchor Predictably Shapes Ratings of Perceived Effort: A Randomized Crossover Trial

Background Ratings of perceived effort (RPE) are used to prescribe and monitor training. Yet, the influence of how the upper anchor (“10”) is defined remains underexplored, despite holding theoretical and practical value. Here, we examined whether modifying the upper anchor predictably modifies RPEs during isometric exercises. Methods We conducted a within-subject, randomized crossover study in 26 resistance-trained adults. Participants performed isometric contractions at 20–100% of maximal voluntary contraction (MVC) in three exercises: unilateral plantar flexion, unilateral knee extension, and the isometric mid-thigh pull. After each contraction, participants reported RPE (0–10) relative to one session-specific anchor: same-task (maximal effort in the task performed), different-task (maximal effort in the isometric mid-thigh pull), or self-selected (the most effortful task ever experienced or imagined). We estimated expected RPEs and slopes relating RPE to %MVC for each exercise–anchor combination. Preregistered comparisons assessed anchor effects, muscle-mass dose–response, and approximate scale invariance across anchors. Results Anchor type substantially influenced RPE. Same-task anchors consistently produced the highest RPEs, self-selected the lowest, and different-task anchors intermediate values, with effects most pronounced at 80–100% MVC. The ratings increased with %MVC across all conditions. Under the self-selected anchors, exercises engaging greater muscle mass tended to yield higher RPEs. The relative differences between exercises were largely preserved across anchors, indicating that anchor choice alters RPE while maintaining approximate scale invariance. Conclusions Upper anchors predictably shape RPE across tasks and intensities. Researchers and applied practitioners using RPE in resistance training should explicitly define, justify, and consistently report anchoring procedures, and align anchor choice with the intended purpose to support valid interpretation and comparisons.