International Journal of Exercise Science 14(4): 971-979, 2021. The purpose of this study was to determine whether the number of warm-up sets and relative intensity impacts the prediction of velocity-based one-repetition maximum (1RM) values. Twenty resistance-trained individuals (males: n = 10, females: n = 10) participated in this study. Warm-up sets consisted of subject’s bench-pressing loads at 50 (five-repetitions), 70 (three-repetitions), and 90% (one-repetition) of estimated 1RM. A maximum of four attempts were performed to determine 1RM, while recording mean concentric velocity (MCV)using a linear position transducer during warm-up and 1RM trials in order to develop load-velocity profiles. Specifically, four different velocity-based 1RM equations (EQ) were developed from the warm-up sets of 50, 70, and 90% (MCV-EQ1), 50 and 90% (MCV-EQ2), 70 and 90% (MCV-EQ3), and 50 and 70% (MCV-EQ4). Constant error (CE) for the MCV prediction equations were not statistically significant for any comparisons (CEs = 0.80 to 2.96kg, all p \u3e 0.05). Correlation coefficients between the MCV prediction methods and measured 1RM were near perfect for all comparisons (r ≥ 0.98, all p \u3c 0.001). The standard error of estimate (SEE) and 95% limits of agreement (LOAs) were lowest for MCV-EQ1 (7.86 kg and ± 15.00 kg, respectively) and slightly higher for MCV-EQ3 (9.24 kg and 17.74 kg, respectively). Nonetheless, SEEs and 95% LOAs for MCV-EQ2 (8.10 kg and ± 15.55kg, respectively) and MCV-EQ4 (8.38 kg and ± 16.08 kg, respectively) were similar as MCV-EQ1. Current study results indicated that an additional warm-up set only slightly increases the accuracy of velocity-based 1RM estimations. Furthermore, larger differences in relative intensity will help produce slightly more accurate 1RM values
