Background High volumes of work affect the movement technical quality, reducing the muscular capacity to develop high magnitudes of force. One of the most important parameters that we can use to regulate the training loads are the inter-repetition rests (IRR). The purpose of this study was to compare the Peak Power output (PP) magnitudes in three different inter-repetition length sets with Optimal Load (OL) in Bench Press (BP).

Methods Our sample was formed by 16 male physical education students (age: 23.6±2.1 years; height: 178.2±6.9 cm; mass: 78.3±7.2 kg; 1RM: 90.2±13.9 kg; 1RM/mass: 1.15±0.16), who performed the BP test with different IRR with OL (48.8±7.2% of 1RM; 44.2±11.5 kg). After establishing the bench press 1-RM and OL, all participants performed three sets of work: IRR15s (1 set×15 repetitions with 15 s inter-repetition rests), IRR10s (1 set×15 repetitions with 10 s inter-repetition rests) and IRR5s (1 set×15 repetitions with 5 s inter-repetition rests) separated by 15 min each.

Results There were no mechanical significant differences among the 15 repetitions when performing the protocol with IRR15s, although there was a slight tendency to decrease the maximal values of PP (1st Rep.: 324.1±18.9 vs. 15th Rep.: 250.9±16.4 W). Significant decreases were observed from the second repetition in the IRR10s (1st Rep.: 346.2±82.2 vs. 2nd Rep.: 296.6±64.0 W) (13.8 %; p=0.002; ES: –0.60; IC 95%: 14.16–85.07) and IRR5s (1st Rep.: 348.2±70.9 vs. 2nd Rep.: 290.5±72.8) (16.8±11.4%; p=0.001; ES: -0.82; IC 95%: 18.57–96.93).

Conclusions The longer IRR allows the higher number of efficient repetitions (IRR15s>IRR10s >= IRR5s). In our study, when performing IRR15s there were no significant PP decreases observed, while in IRR10s and IRR5s significant decreases were found from the second repetition.