(15) DOES SET STRUCTURE INFLUENCE THE ACCURACY OF REPETITIONS IN RESERVE IN THE BACK SQUAT?

Purpose: The purpose of this study was to examine the differences in the accuracy of repetitions in reserve (RIR) and exercise performance between traditional sets (TS) and cluster sets (CS) in the back squat. Methods: 13 resistance-trained subjects took part in this study including 6 women (age=23±2 years, height=162.3±2.1 cm, body mass=64.9±8.3 kg, relative one repetition maximum [1RM] back squat=1.56±0.29 kg/kg) and 7 men (age=23±2 years, height=168.7±4.4 cm, body mass=91.1±15.2 kg, relative one repetition maximum [1RM] back squat=1.55±0.26 kg/kg). Each subject participated in three total sessions. During the first visit, subjects completed a 1RM back squat and a set to failure at 85% of the established 1RM. During the remaining two visits, participants were randomized into either the CS or TS condition where they performed singles with 40s intra-set rest (CS) or continuous repetitions with no intra-set rest (TS), respectively. Regardless of condition, participants had three minutes of inter-set rest. After completing warm-ups at 30%, 50%, 65% and 75% of 1RM, working sets were performed at 85% 1RM. Working sets 1 and 2 consisted of three total repetitions, whereas, working sets 3 and 4 consisted of performing repetitions until an 8 RPE and a 10+ RPE, respectively. RPE and RIR were recorded following each set. The RIR_ERROR was then calculated as the absolute difference between the sum of the total number of repetitions completed and RIR during sets 2 and set 3 (i.e., predicted maximum repetitions) from the total reps completed in set 4 (i.e., maximum repetitions completed). Each visit was separated by at least 48 hours, but no more than one week and were completed at the same time of day (±1 h). Participants were instructed to refrain from exercise 24 hours prior to each visit and caffeine 8 hours prior to each visit. separate condition (TS/CS) x set (S2/S3) repeated measures ANOVAs were run for RIR_ERROR (predicted – actual) and RIR. Results: For RIR_ERROR, there was no condition x set interaction effect (p=0.774) or main effect for set (p=0.384). However, there was a main effect for condition (p=0.003), whereby when collapsed across set, RIR_ERROR was significantly greater in CS (13.3 ± 10.3 reps) when compared to TS (2.2 ± 11.4 reps). For RIR, there was no condition x set interaction effect (p=0.077); however, there were significant main effects for condition (p=0.034) and set (p=0.008). Post-hoc analysis indicated that when collapsed across set, RIR was greater in CS (3.42 ± 0.44 reps) when compared to TS (2.77 ± 0.34 reps). Additionally, when collapsed across condition, RIR estimates were significantly greater in set 2 (4.23 ± 0.72 reps) when compared to set 3 (1.96 ± 0.04 reps). Conclusions: The primary finding of this investigation was that CS resulted in more RIR_ERROR than TS. It is possible that greater RIR_ERROR is due to training further from failure and/or the novelty of the CS structure to the participants. Additionally, our results suggest that RIR may be influenced by the set structure and set parameters, while RIR_ERROR was only affected by the set structure. Practical Applications: Our results suggest clusters led to more error in RIR than traditional; thus, practitioners can expect subjective feedback from clients to be more inaccurate when rating cluster sets in comparison to traditional sets. If RIR is used to prescribe training when implementing cluster sets, coaches may consider using additional metrics in conjunction with RIR to ensure the intended stimulus is employed. Acknowledgements: None