Effects of different between test rest intervals in reproducibility of the 10-repetitions maximum load test: A pilot study with recreationally resistance trained men

The purpose of this study was to compare the effect of 24-, 36-, 48-, 72- and 96-hours between-test rests intervals on the reproducibility of the 10RM smith machine back squat (BS), bench press (BP) and leg press at 45 degrees (LP45) exercises. Twelve resistance trained men (26.6 ± 4.5 yrs; 179.0 ± 5.5 cm; 92.2 ± 24.6 kg) performed five sets of identical 10 repetition maximum (10RM) tests for the BS, BP, LP45 exercises, each set with a different interval between tests: 1) twenty-four hours (Post-24), 2) thirty-six hours (Post-36), 3) forty-eigth hours (Post-48), 4) Seventy-two (Post-72), and 5) ninety-six hours (Post-96). Significant difference was observed in posttests loads for BS in Post-24 (p<0.001; ∆% = -12.62), Post-36 (p<0.001; ∆% = -6.57), and Post-96 (p=0.015; ∆% = 6.84) in comparison to pretests day. Similarly, statistically significant difference was observed in posttests loads for BP in Post-24 (p<0.001; ∆% = -9.22), Post-36 (p=0.032; ∆% = -3.04), and Post-96 (p<0.001; ∆% = 5.37) in comparison to pretests day. Additionally, a statistically significant difference was observed in posttests loads for LP45 in Post-24 (p<0.001; ∆% = -16.55), Post-36 (p=0.032; ∆% = -5.09), and Post-96 (p<0.001; ∆% = 5.54) when compared to pretests day. The reproducibility of 10RM was examined using intraclass correlation coefficients; BS: 0.944, 0.977, 0.988, 0.986, and 0.954 for Post-24, Post-36, Post-48, Post-72, and Post-96, respectively; BP: 0.894, 0.966, 0.966, 0.960, and 0.976; and LP45: 0.832, 0.957, 0.984, 0.974, and 0.977 5. Based on the findings, the optimal between test rest interval duration for 10RM testing, to provide the best reproducibility, in resistance trained men appears to be 48 to 72 hours for the BS, BP, and LP45 exercises.