The Validity & Reliability of the Repetitions in Reserve Based Rating of Perceived Exertion Scale in Single Joint Exercise

Introduction: Intentional regulation and individualization of resistance training schemes are imperative when structuring a resistance training program. Optimal adaptation cannot be expected without proper manipulation of training variables such as load and volume. Load is traditionally prescribed by testing a given exercise’s repetition maximum and basing intensity from that load. This method of intensity regulation may be limited, considering it fails to recognize the day-to-day undulation of individual performance which can be impacted by several variables. A flexible method of regulating load and volume would be of use for those undergoing a resistance training program. The repetitions in reserve-based rating of perceived exertion (RIR-RPE) scale is a perception-based tool used to autoregulate the intensity of a lift. RIR-RPE allows for the user to govern programming variables such as load and volume on a day-to-day basis. Purpose: The aim of this study was to assess the validity and reliability of the RIR-RPE scale in single joint resistance exercise. Methods: 12 participants (7 male and 5 female) (age: 20.42 ± 1.98 years, training age: 5.83 ± 3.19 years, weight: 76.59 ± 16.74 kg, height: 1.72 ± 0.09 m) volunteered for this three-session study, each separated by a minimum of 48 hours. Session one included anthropometric assessments and 8RM tests for unilateral bicep curl and leg extension exercises. Participants were also familiarized to the RIR-RPE scale in session one. In session two, participants completed three sets at 70, 75, and 80% of predicted one repetition maximum for nine, seven, and five repetitions, respectively. After completing the assigned number of repetitions, participants were asked to pause and indicate a value on the RIRRPE scale before continuing the set to technical failure. Velocity was measured on the iv repetition RIR-RPE was gathered and the final repetition before failure. Session three was the same as session two to assess reliability. Participants were randomized and blinded to the order in which they were exposed to the intensities. Results: Participants tended to underpredict RIR by approximately one repetition (1.02 ± 0.32 ) on average. Participants became more accurate in their predictions in session two (0.93 ± 0.44) compared to session one (2.78 ± 0.73). Calculations of intraclass correlation coefficients for absolute agreement revealed moderate to strong agreement between estimated- and actual-RIR in the bicep curl with a range of (0.51 – 0.91) and weak to moderate agreement in the leg extension with a range of (0.183 – 0.66). Reliability was low to moderate in the bicep curl with a range of (0.26 – 0.64) and low in the leg extension exercise with a range of (0 – 0.102). A negative relationship between RIR-RPE and velocity was at 70% (r = - 0.62, p = 0.023), 75% ( r = - 0.86, p = 0.00017), 80% (r = - 0.42, p = 0.15) in the bicep curl and at 70% (r = - 0.8, p = 0.0016), 75% (r = - 0.77, p = 0.0021), 80% (r = - 0.67, p = 0.12) in the leg extension. Conclusions: The RIR-RPE scale is not perfectly accurate. The meaningfulness of an underprediction on one RIR has yet to be investigated. Individuals using the RIR-RPE scale tend to get more accurate over with experience. The RIR-RPE scale may not be reliable in single joint exercise until the individual using the scale has adequate experience. Practical Applications: Athletes and practitioners may consider using the RIR-RPE scale as a flexible way of autoregulating resistance training variables