Hernandez, DJ, Healy, S, Giacomini, ML, and Kwon, YS. Effect of rest interval duration on the volume completed during a high-intensity bench press exercise. J Strength Cond Res XX(X): 000-000, 2020-Between-set rest intervals (RIs) are one of the most important variables in resistance training; however, no known research has investigated the effects of RIs greater than 5 minutes during high-intensity strength training. The purpose of this research was to examine the effects of 3 different RIs on repetition sustainability and training volume (sets × reps × resistance) during a high-intensity bench press exercise. Fifteen resistance-trained male subjects (mean ± SD, age = 25.5 ± 4.5 years, and bench press 1 repetition maximum [1RM] ratio [1RM/body mass] = 1.39 ± 0.1) completed 3 experimental sessions, during which 4 sets of the bench press were performed with 85% of 1RM load. Subjects performed the bench press using 3 different RIs in a random counterbalanced design. Data were analyzed using both a one- and two-way analysis of variance with repeated measures. As sets progressed, repetitions were significantly different (p < 0.05) between all RIs, and only the 8-minute RI (p < 0.05) allowed for the complete sustainability of repetitions over 4 consecutive sets. Subjects attained the greatest training volume (p < 0.05) using an 8-minute RI between sets compared with a 2- or 5-minute RI. Similarly, a significantly greater training volume was achieved using the 5-minute RI compared with the 2-minute RI. Resistance-trained men, with the goal of greater volume during strength training, would benefit from longer RIs, specifically using an 8-minute RI between 4 consecutive sets of a bench press exercise.