Effects of Self-Selected Rest Interval between Sets on Resistance Training Session Total Volume

Purpose: To investigate the effects of self-selected and different fixed rest intervals (RI) lengths between sets on the volume-load of upper- and lower-body resistance exercises in resistance-trained individuals. Methods: Nineteen resistance-trained males performed six randomized resistance training (RT) sessions separated by at least 72 hours, including bench press and back squat exercises. Each RT session consisted of four sets of maximum repetitions with a 6RM load for both exercises with different rest intervals (RI), 2-min, 5-min, and a self-selected RI length. In the self-selected RI session, subjects started subsequent sets when they indicated perceived readiness (PR) at 4. Results: For the back squat exercise, volume-load and repetitions were similar across conditions (p > 0.05), whereas self-selected rest intervals were longer than those in the 2-min session across all sets (p ≤ 0.001). No significant differences in PR scores were observed between sessions (p > 0.05). For the bench press exercise, volume-load was higher in both the self-selected (p ≤ 0.001) and 5-min (p ≤ 0.01) sessions than in the 2-min session. The number of repetitions performed during the third and fourth sets was lower in the 2-min session than in both the self-selected and 5-min conditions (p < 0.05). Self-selected rest intervals were shorter than 5 min during the first two intervals (p = 0.001; p = 0.006, respectively) but longer than 2 min across all intervals (p ≤ 0.001). PR scores were significantly higher during the third rest interval than during the first in both the 5-min (p = 0.045) and 2-min (p = 0.010) sessions. Conclusions: Longer or self-selected intervals were beneficial for maintaining volume-load during the bench press but not necessary for the back squat.