Background/Objective Understanding the impact of stressors on the rating of perceived exertion (RPE) is relevant from a performance and exercise adherence/participation standpoint. Athletes and recreationally active individuals dehydrate during exercise. No attempt has been made to systematically determine the impact of exercise-induced dehydration (EID) on RPE. The present meta-analysis aimed to determine the effect of EID on RPE during endurance exercise and examine the moderating effect of potential confounders. Methods Performed on raw RPE values using random-effects models weighted mean effect summaries and meta-regressions with robust standard errors, and with a practical meaningful effect set at 1 point difference between euhydration (EUH) and EID. Only controlled crossover studies measuring RPE with a Borg scale in healthy adults performing §30 min of continuous endurance exercise while dehydrating or drinking to maintain EUH were included. Results Sixteen studies were included, representing 147 individuals. Mean body mass loss with EUH was 0.5 ± 0.4%, compared to 2.3 ± 0.5% with EID (range 1.7e3.1%). Within an EID of 0.5e3% body mass, a maximum difference in RPE of 0.81 points (95% CI: 0.36e1.27) was observed between conditions. A meta-regression revealed that RPE increases by 0.21 points for each 1% increase in EID (95% CI: 0.12 e0.31). Humidity, ambient temperature and aerobic capacity did not alter the relationship between EID and RPE. Conclusion Therefore, the effect of EID on RPE is unlikely to be practically meaningful until a body mass loss of at least 3%.
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