Perceptual Demands in CrossFit®: Convergent Validity of sRPE and the Relative Role of Session Phases in a Prospective Observational Study

The purpose of this study was to examine the convergent validity and reliability of the session rating of perceived exertion (sRPE) in complete CrossFit® sessions by comparing it with a weighted RPE measure (RPEW) obtained from different session phases. Twenty-four recreational practitioners (13 men and 11 women; age 34.5 ± 8.3 years; height 172.9 ± 11.2 cm; body mass 76.2 ± 15.2 kg) completed 28 standardized sessions (~60 min) consisting of warm-up, strength/skill, Workout of the Day (WOD), and cooldown phases. Phase-specific RPE values were collected after each session component, and a global sRPE was recorded ~30 min post-session. Results showed that RPEW (5.8 ± 1.5) was significantly lower than sRPE (6.8 ± 1.4; p < 0.001, d = 0.69), resulting in a higher training load estimated by sRPE (+15.5%). Bland–Altman analysis revealed a positive bias and wide limits of agreement, while relative reliability was moderate to good (ICC = 0.73–0.77). Multiple regression analysis indicated that WOD RPE explained 70% of the variance in sRPE (R2 = 0.70, p < 0.001), confirming its role as the primary perceptual determinant. In conclusion, sRPE represents a valid, simple, and cost-effective tool for monitoring internal load in CrossFit®. However, it tends to overestimate RPEW and shows substantial interindividual variability, limiting its precision for individualized monitoring. Coaches and practitioners should therefore interpret sRPE values with caution, especially considering the strong influence of the final session phase.