Effect Of Proximity To Failure During Resistance Training On Bench Press Strength

PURPOSE: To compare changes in bench press one-repetition maximum (1RM) between training programs with different proximities to failure using the repetitions in reserve (RIR)-based rating of perceived exertion (RPE) scale. METHODS: Twenty-nine males (height: 174.60 ± 6.23 cm, body mass: 80.43 ± 10.97 kg, bench press one-repetition maximum-1RM relative to body mass: 1.33 ± 0.17) with ≥2 yrs of training experience were assigned to one of three groups: 1) 4-6 RPE, n = 10 (4-6 RIR), 2) 7-9 RPE, n = 10 (1-3 RIR), or 3) 7-9+ RPE, n = 9 (1-3 RIR and last set to momentary failure) for 8wks. Pre and post 1RM strength testing was performed 48 hours before the first training session and 48 hours after the last training session, respectively. All groups performed the bench press 3x/wk on non-consecutive days (e.g., Mon., Wed., Fri.) using the same number of sets and repetitions on an undulating resistance training program, which linearly decreased repetitions throughout. Week 1 served as an introductory week in which fewer sets were performed at a lower RPE. Week 8 was a taper with low repetitions in sessions 1 and 2, followed by post-testing in session 3. In weeks 2-7 (i.e., main training period), 10 weekly sets were performed. Subjects were instructed to select a load that would result in a set within the desired RPE range. A general linear model was fit to analyze changes in strength between RPE groups when adjusted for baseline strength, and was presented with 95% confidence intervals. Additionally, equivalence testing with 90% confidence intervals was performed with standardized effect thresholds set at ±0.25 to evaluate the statistical similarity of changes between groups. RESULTS: Increases in 1RM bench press were observed in all groups (4-6 RPE: +9.09 kg [5.00-13.19], 7-9 RPE: +9.76 kg [5.64-13.88], 7-9+ RPE: +5.11 kg [0.77-9.45]), with small between group effect sizes observed comparing 4-6 vs. 7-9+ RPE (g = 0.20 [0.01-0.38]) and 7-9 vs. 7-9+ RPE (g = 0.23 [0.04-0.42]). Additionally, statistical similarity was observed between the 4-6 and 7-9 RPE groups (g = -0.03 [-0.21-0.14]). CONCLUSIONS: Our findings indicate that resistance training with 4-6 RPE and 7-9 RPE produce statistically similar bench press strength improvements at the given equivalence threshold; however, other between group comparisons remain statistically inconclusive.