Factors influencing the accuracy of the repetition in reserve scale in resistance training: a systematic review

Abstract

Background: This systematic review aims to elucidate the primary factors influencing the accuracy of Repetitions in Reserve (RIR) scale utilization in resistance training among adults. Methods: A comprehensive search of PubMed, Scopus, Web of Science, and SPORTDiscus databases yielded 520 potential studies, and 26 were selected for inclusion. Methodological quality was assessed using the Newcastle-Ottawa Scale. Results: Greater accuracy was found in utilizing the RIR scale at greater proximity to muscle failure, particularly in exercises involving the upper limbs. The accuracy decreased as the number of repetitions increased and relative load (as a percentage of 1 repetition maximum) decreased. Conclusion: The findings suggest that the RIR scale accuracy is enhanced when sets are per- formed closer to muscle failure and at higher load intensities. This highlights the importance of considering proximity to failure and intensity of load when utilizing the RIR scale in resist- ance training programs