Effects of Different Between Test Rest Intervals in Reproducibility of the 10-Repetition 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 rest intervals on the reproducibility of the 10-RM 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 (10-RM) 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-eight hours (Post-48), 4) seventy-two (Post-72), and 5) ninety-six hours (Post-96). Significant differences in 10-RM from pretest to posttest were observed for BS in Post-24 ( < 0.001; Δ% = -12.62), Post-36 ( < 0.001; Δ% = -6.57), and Post-96 ( = 0.015; Δ% = 6.84). Similarly, significant differences in 10-RM from pretest to posttest were observed for BP in Post-24 ( < 0.001; Δ% = -9.22), Post-36 ( = 0.032; Δ% = -3.04), and Post-96 ( < 0.001; Δ% = 5.37). Finally, significant differences in 10-RM from pretest to posttest were observed for LP45 in Post-24 ( < 0.001; Δ% = -16.55), Post-36 ( = 0.032; Δ% = -5.09), and Post-96 ( < 0.001; Δ% = 5.54). The reproducibility of 10-RM 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 10-RM testing, to provide the best reproducibility, in resistance trained men appears to be 48 to 72 hours for the BS, BP, and LP45 exercises.