Metabolic Responses To Endurance Exercise Anchored To Vigorous Ratings Of Perceived Exertion

Recommendations for cardiorespiratory endurance (CE) exercise are based on vigorous ratings of perceived exertion (RPE), percentages of maximal heart rate (HRmax) or volume of oxygen consumption (V̇O2max). These intensities are extrapolated to a power output (P) or velocity. Previous work has demonstrated dissociations of the metabolic responses when exercise is anchored to a constant RPE (RPE-clamp) due to alterations in P to maintain the designated perceptual intensity. However, the specific metabolic responses during vigorous RPE-clamp exercise (RPE=14-17) are unclear, and it is unknown if the resulting responses are within the recommended range for improvements in CE (64-90% V̇O2max). PURPOSE: This study examined the metabolic (V̇O2) and P responses to RPE-clamp exercise at RPE 14 (RPE14) and RPE 17 (RPE17). METHODS: Twenty-one participants (Age=22±3yrs; Height=175.0±9.5cm; Mass=73.7±16.1kg) performed a graded exercise test to determine V̇O2max and peak power output (PP), followed by trials to exhaustion, up to 60 min, at RPE14 (time to exhaustion [TLim]=60.0±0.0min) and RPE17 (TLim=59.5±2.3 min) on a cycle ergometer. V̇O2 and P were normalized to their respective values at PP at each 10% of TLim. RESULTS: Two-way repeated measures ANOVA indicated there were significant RPE x time interactions (p<0.05) for V̇O2 and P. Follow-up analyses and Bonferroni-corrected, pairwise comparisons indicated that RPE17 V̇O2 (65±8%V̇O2max[means±SD across entire trial]) and P (52±12%PP) were greater than RPE14 (61±4%V̇O2max; 48±7%PP) from 0-20% and 90% TLim (p<0.001-0.022). In addition, V̇O2 peaked at 10% TLim for both RPE14 and RPE17, followed by significant decreases after 30% and 20% TLim, respectively. P significantly decreased after 10% TLim and plateaued after 50% TLim for RPE14 and RPE17. The V̇O2 at RPE14 and RPE17 were above the recommended prescription guidelines from 10-20% and 0-40% TLim, respectively. CONCLUSIONS: RPE-clamp exercise at RPE17, but not RPE14, elicited a vigorous V̇O2 intensity for at least 20 minutes, meeting the current guidelines for improvements in CE. Both V̇O2 and P at RPE14 and RPE17 converged by the end of trial, suggesting afferent feedback and efferent feedforward inputs regulate exercise intensity at a theoretical sensory tolerance limit that warrants further examination. National Strength and Conditioning Doctoral Student Research Grant