Conlon, JA, Haff, GG, Tufano, JJ, and Newton, RU. Application of session rating of perceived exertion among different models of resistance training in older adults. J Strength Cond Res XX(X): 000–000, 2015—The aim of this study was to assess the relationship between external measures of resistance training (RT) workload and intensity, volume load (VL) and training intensity (TI), and related internal measures, session load and session rating of perceived exertion (sRPE), across a chronic RT intervention and between different models of RT in older adults. Forty-one healthy, untrained older adults (female, 21; male, 20; age, 70.9 ± 5.1 years; height, 166.3 ± 8.2 cm; weight, 72.9 ± 13.4 kg) were randomly stratified into 3 RT groups: nonperiodized (NP), block periodized (BP), or daily undulating periodized (DUP). They completed a 22-week RT intervention at a frequency of 3 d·wk−1. All training was executed on RT machines, and training volume was equalized between training groups based on total repetitions. Session RPE was measured 10–15 minutes after each training session. There were no meaningful relationships between VL and session load or TI and sRPE. Also, no significant differences were detected between training groups for mean sRPE across the training intervention. Based on these results, session load and sRPE do not appear to be valid markers of RT workload and intensity when compared with established external measures in healthy untrained older adults. However, sRPE and session load may hold promise as monitoring tools in RT that do not involve training to muscular failure. Furthermore, sRPE does not significantly differ between NP, BP, and DUP RT models, highlighting that this measure is not sensitive to such periodization as evident in the present study.