Effect Of Proximity To Failure During Resistance Training On Back Squat Strength

PURPOSE: To compare changes in back squat 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: Fourteen males (height: 175.77 ± 5.72 cm, body mass: 80.15 ± 13.12 kg, squat 1RM relative to body mass: 1.72 ± 0.25) with ≥2 yrs of back squat experience were assigned to one of two groups: 1) 4-6 RPE, n = 7 (4-6 RIR) or 2) 7-9 RPE, n = 7(1-3 RIR) 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. Both groups performed the back squat 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. Weeks 1-3 consisted of 10, 8, and 6 repetitions on sessions 1, 2, and 3, respectively; weeks 4-5 consisted of 9, 7, and 5 repetitions; and weeks 6-7 consisted of 8, 6, and 4 repetitions. Week 1 served as an introductory week in which fewer sets were performed at a lower RPE. Week 8 served as a taper with 4 and 2 repetition days on session 1 and session 2, respectively, followed by post-testing in session 3. In weeks 2-7 (i.e., main training period), 10 weekly sets were performed for each back squat and bench press. Subjects were instructed to select a load in which the set ended with 4-6 RPE or 7-9 RPE. A repeated measures ANOVA was used to assess 1RM changes and independent t-tests compared average intensity (% of 1RM)and total relative volume (% of 1RM × reps). RESULTS: Significant increases in back squat 1RM were observed in both the 4-6 RPE group (142.29 ± 50.05 to 156.07 ± 44.65 kg; p < 0.01; +11.53%; g = 0.23) and 7-9 RPE group (137.57 ± 31.92 to 152.64 ± 30.89 kg; p < 0.01; +11.68%; g = 0.26); however, no significant group × time interactions were observed (p > 0.05). The 7-9 RPE group trained with significantly higher average relative intensity (82.2 ± 5.18 vs. 72.0 ± 4.57 %1RM, p = .002) and performed significantly higher relative volume (338.7 ± 21.46 vs. 380.1 ± 25.83 kg, p = .007). CONCLUSIONS: Our findings indicate that resistance training with 4-6 RPE and 7-9 RPE produce similar back squat strength improvements.