Psychological and physiological moderators of perceived exertion in aerobics: a repeated-measures study

Objectives Perceived exertion is a central marker of exercise intensity, yet individuals differ substantially in how hard a standardized workload feels. This study examined whether anthropometric, physiological, and psychological characteristics moderate the association between achieved heart rate reserve (HRR) and perceived exertion during standardized step-aerobics. Methods A total of 126 young adults (18–35 years; 63 females, 63 males) completed three step-aerobics sessions targeted to light, moderate, and vigorous intensities (40%, 60%, and 75%–80% HRR). Heart rate and rating of perceived exertion (RPE; Borg 6–20) were recorded every 3 min, yielding 1,134 repeated observations. Baseline assessments included anthropometry, bioimpedance-derived body composition, Cooper-test–estimated cardiorespiratory fitness, and psychological questionnaires assessing exercise self-efficacy, BIS/BAS, trait anxiety, interoceptive sensibility (MAIA-2), intensity preference, and intensity tolerance. Repeated-measures generalized estimating equation models tested prespecified HRR × moderator interactions, and exploratory models examined session-specific MAIA-2 effects and the HRR × MAIA-2 × sex interaction. Results Perceived exertion increased strongly with HRR overall (B = 0.167, 95% CI [0.157, 0.176], standardized β = 0.859, p < 0.001), indicating a large and practically meaningful coupling between internal load and perceived exertion. None of the prespecified physiological moderators significantly altered the HRR–perceived-exertion slope, and the interaction effects were small, suggesting limited practical relevance of physiological moderation once exercise was standardized by relative HRR. Psychological moderation effects were also small; the largest estimate was observed for MAIA-2 (HRR × MAIA-2: B = −0.0078, 95% CI [−0.0160, 0.0003], standardized β = −0.040, p = 0.060). In exploratory session-specific models, a 1-SD higher MAIA-2 score was associated with a 0.18-point lower Borg RPE at moderate intensity (B = −0.176, 95% CI [−0.348, −0.003], standardized β = −0.106, p = 0.046), indicating a statistically detectable but small absolute difference in perceived exertion. The HRR × MAIA-2 × sex interaction was not significant (B = 0.011, 95% CI [−0.004, 0.026], standardized β = 0.058, p = 0.137). During vigorous exercise, RPE values clustered near the upper end of the Borg scale, consistent with a perceptual ceiling effect. Conclusion When step-aerobics is standardized by relative internal load, achieved HRR is the dominant determinant of perceived exertion. Physiological status contributes little additional moderation, whereas interoceptive sensibility showed only limited exploratory evidence of a small association with lower perceived exertion at moderate intensity.