Objectives: Rating of perceived exertion scales are commonly used in resistance training (RT) though most suffer from conflation of perceptions of both effort and discomfort by participants. The aim of this study was to examine reliability of trainee ratings of perceived effort (RPE-E) and discomfort (RPE-D) using two novel scales in addition to reliability and validity of trainer RPE-E. Design: Participants underwent 3 RT trials over a period of three weeks. Methods: Seventeen participants (males n = 6, females n = 11, age 63 ± 16 years) completed 5 RT exercises for a single set using a load permitting a self-determined 6 repetition maximum (meaning they determined inability to complete further repetitions if attempted i.e. they predicted momentary failure on the next repetition). Trainers completed their rating of RPE-E, followed by participants reporting of RPE-E and RPE-D immediately after completion of the exercises. Spearman’s correlations examined the relationship between RPE-E and RPE-D. Reliability was examined as standard error of measurement (SEM) calculated for each outcome across the 3 trials (intra-rater), in addition to agreement between trainers (inter-rater), and agreement between trainer and trainee RPE-E. Results: Correlations between RPE-E and RPE-D were significant but weak (r = .373 to 0.492; p < 0.01). Intra-rater SEMs for trainee RPE-E ranged from 0.64 to 0.85, trainee RPE-D ranged from 0.60 to 1.00, and trainer RPE-E ranged from 0.56 to 0.71. Inter-rater SEMs for trainer RPE-E ranged 0.25 to 0.66. SEMs for agreement between trainer and trainee RPE-E ranged from 1.03 to 1.25. Conclusions: Results suggest participants were able to differentiate RPE-E and RPE-D and that the reliability for both trainee measures of RPE-E and RPE-D, in addition to trainer RPE-E is acceptable. Further, trainer RPE-E appeared to have acceptable validity compared to trainee RPE-E. These scales might be adopted in research examining the dose-response nature of effort upon RT outcomes and trainers might use them to inform programming.