Gentil, P, Bottaro, M, Oliveira, E, Veloso, J, Amorim, N, Saiuri, A, and Wagner, DR. Chronic effects of different between-set rest durations on muscle strength in nonresistance trained young men. J Strength Cond Res 24(1): 37-42, 2010-The purpose of the study was to investigate the effects of different between-set rest interval durations on muscle strength after 12 weeks of resistance training. After baseline tests, 34 nonresistance trained college-aged men were matched and randomly assigned to 2 groups. Both groups trained twice a week and performed the same exercises and the same work output with 2 sets of 8 to 12 repetitions until volitional fatigue. One group (n = 18, 21.4 ± 3.2 yr; 73.8 ± 14.0 kg; 175.9 ± 7.8 cm) used short-rest intervals (SR) with a work rest ratio of approximately 1:3; the other (n = 16, 22.4 ± 2.6 yr; 73.1 ± 13.6 kg; 171.9 ± 8.2 cm) used long-rest intervals (LR) with a work rest ratio of approximately 1:6. Leg press and bench press 1 repetition maximum (1RM) were measured at baseline and after the end of the training period. The increases in 1RM for bench press were 14.4 ± 8.1% for the SR group and 10.5 ± 6.4% for the LR group (p < 0.05). For the leg press, the increases were 17.5 ± 9.2% with SR training and 17.8 ± 12.3% for the LR group (p < 0.05). The results did not reveal significant differences between SR and LR for the bench press or leg press 1RM (p > 0.05). Our data suggest that gains in maximum strength in nontrained men are not dependent on the length of the rest interval between sets. Therefore, personal trainers and strength coaches can advise beginning lifters to use short rest intervals to make best use of their time in the weight room.