Percentage-based and Autoregulated-based Resistance Training Loading Produce Similar Lower Body Hypertrophy Outcomes

Researchers and practitioners have used the resistance training-specific rating of perceived exertion (RPE) scale to individualize load prescription. PURPOSE: To compare changes in muscle thickness (MT) of the vastus lateralis at 50% (VL50) and 70% (VL70) and vastus medialis at 70% (VM70) femur length between percentage-based training (PBT) and autoregulated-based training (ABT) via RPE. METHODS: Eleven males (age: 23±4yrs, body mass: 77.4±7.7kg, body fat: 9.5±3.8%) with at least two yrs. of training experience and a minimum one-repetition maximum (1RM) of 1.5 and 1.25x bodyweight on the squat and bench press respectively, were assigned to one of two groups: PBT (n=6) or ABT (n=5) for 8 weeks. Forty eight hours following pre-testing MT via ultrasound, both groups performed the squat and bench press 3x/wk. on non-consecutive days (i.e. Mon., Wed., Fri.) using the same number of sets and repetitions following an undulating resistance training program, which linearly increased load and decreased repetitions throughout. Weeks 1-3 consisted of 8, 6, and 4 repetitions on Mon., Wed., and Fri., while weeks 4-5 consisted of 7, 5, and 3 repetitions, with 6, 4, and 2 repetitions being performed during weeks 6-7. Week 8 served as a taper with 4 and 3 repetition days on Mon. and Wed. and post-testing on Fri. Load increased during each week in PBT from 65, 70 and 75% in week 1 to 82.5-92.5% of 1RM in week 7. In ABT there was no prescribed load but subjects were instructed to select a load in which the set ended with a 5-7 RPE in week 1 and progressed to an 8-10 RPE in week 7. A 2x2 repeated measures ANOVA was used with significance set at p≤0.05. RESULTS: There was a significant time effect for VL50 (25.4±3.28 to 28.1±4.64mm; p=0.04; +10.42%) in PBT but not in ABT (26.72±3.75 to 28.45±3.42 mm; p=0.16; +6.47%). The time effect for VL70 in PBT approached significance (23.69±3.42 to 26.81±2.89 mm; p=0.06; +13.17%), and there was no significant change for VL70 in ABT (24.61±3.59 to 26.31±4.06 mm; p=0.33; +6.91%). There was a significant time effect for VM70 in PBT (17.93±3.25 to 19.25±3.36 mm; p=0.05; +7.36%), but not in ABT (19.63±4.30 to 20.50±4.00 mm; p=0.17; +4.43%). Additionally, there were no group differences (VL50: p=0.72; VL70: p=0.92; VM70: p=0.54). CONCLUSION: Our findings indicate that PBT and ABT strategies produce similar lower body hypertrophy.