Subjective Measures in the Service of Exercise Performance

Background: Despite the progress made in the study of subjective measures in resistance-training, some questions remain unanswered. Here we investigated if ratings of perceived effort (RPE) can predict task-failure and bar-velocity across exercises and loads as a primary outcome, and whether a battery of subjective measures differ as a function of the lifted loads as a secondary outcome.

Methods: In this preregistered study, twenty resistance-trained subjects (50%-females) first completed one repetition-maximum (RM) tests of the barbell-squat and bench-press. On the second and third sessions, subjects completed two sets of squats followed by two sets of bench-press to task-failure, using 70% or 83% of 1RM, while bar-velocity was recorded. RPE scores were recorded after every repetition. Rating-of-fatigue, affective-valence, enjoyment, and load-preferences were collected after sets- and sessions-completion.

Results: Across conditions, RPE was strongly correlated with reaching task-failure (r= .86) and moderately correlated with bar-velocity (r= -.58). Our model indicates that an increase in one RPE unit is associated with an 11% shift towards task-failure, and a 4% reduction in bar-velocity, with steeper slopes observed in the heavier condition. Negligible differences were observed between the load-conditions in rating-of-fatigue, affective-valence, enjoyment, and load-preference.

Conclusion: RPE scores, collected on a repetition-by-repetition basis, accurately reflected reaching task-failure across loads and conditions. Hence, RPE can be used to prescribe repetition numbers during ongoing sets. The negligible differences between load conditions in the subjective measures indicate that when sets are taken to task-failure, loads can be selected based on individual preferences.