This study aimed to analyze the intra-device agreement of a new linear position transducer (Vitruve, VT) and the inter-device agreement with a previously validated linear velocity transducer (T-Force System, TF) in different range of velocities. A group of 50 healthy, physically active men performed a progressive loading test during a bench press (BP) and full-squat (SQ) exercise with a simultaneous recording of two VT and one TF devices. The mean propulsive velocity (MPV) and peak of velocity (PV) were recorded for subsequent analysis. A set of statistics was used to determine the degree of agreement (Intraclass correlation coefficient [ICC], Lin’s concordance correlation coefficient [CCC], mean square deviation [MSD], and variance of the difference between measurements [VMD]) and the error magnitude (standard error of measurement [SEM], smallest detectable change [SDC], and maximum errors [ME]) between devices. The established velocity ranges were as follows: >1.20 m·s⁻¹; 1.20–0.95 m·s⁻¹; 0.95–0.70 m·s⁻¹; 0.70–0.45 m·s⁻¹; ≤0.45 m·s⁻¹ for BP; and >1.50 m·s⁻¹; 1.50–1.25 m·s⁻¹; 1.25–1.00 m·s⁻¹; 1.00–0.75 m·s⁻¹; and ≤0.75 m·s⁻¹ for SQ. For the MPV, the VT system showed high intra- and inter-device agreement and moderate error magnitude with pooled data in both exercises. However, the level of agreement decreased (ICC: 0.790–0.996; CCC: 0.663–0.992) and the error increased (ME: 2.8–13.4% 1RM; SEM: 0.035–0.01 m·s⁻¹) as the velocity range increased. For the PV, the magnitude of error was very high in both exercises. In conclusion, our results suggest that the VT system should only be used at MPVs below 0.45 m·s⁻¹ for BP and 0.75 m·s⁻¹ for SQ in order to obtain an accurate and reliable measurement, preferably using the MPV variable instead of the PV. Therefore, it appears that the VT system may not be appropriate for objectively monitoring resistance training and assessing strength performance along the entire spectrum of load-velocity curve.

Background: This study examined the maximum number of repetitions (MNR) that can be completed to muscular failure at different relative loads in the prone bench pull (PBP) exercise, its inter-individual variability, and potential anthropometric factors associated with this variability in male and female highly trained rowers. Methods: Twenty-five national- and international-level rowers (16 men and 9 women) completed an incremental loading test to determine the one-repetition maximum (1RM) and velocity associated with each relative load, followed by four sets to muscular failure at 50, 60, 70, and 80% 1RM, performed in a randomized order, with 5–7 days between sessions. Peak velocity of the fastest (Vmax-Best) and last (Vmax-Last) repetitions, velocity loss (VL), and MNR were recorded. Results: MNR progressively decreased as relative load increased (p < 0.001), ranging from 38.2 ± 7.1 to 9.4 ± 2.2 repetitions in men and from 46.9 ± 9.7 to 10.4 ± 2.3 repetitions in women. Considerable inter-individual variability in MNR was observed across relative loads (CV = 14.2–25.8%) for both sexes. Vmax-Best progressively decreased with increasing relative load (p < 0.001), whereas no statistically significant differences in Vmax-Last were detected across loads (p = 0.606), with lower values observed in women than in men (p < 0.001). A significant relative load × sex interaction was observed for MNR (p = 0.043), with women completing more repetitions than men at 50% 1RM. Neither Vmax-Best nor the anthropometric variables showed consistent associations with MNR across relative loads. Conclusions: These findings indicate substantial inter-individual variability in the MNR at a given relative load and question the use of fixed repetition targets to prescribe resistance-training volume. Monitoring repetition velocity and VL may be useful for individualizing set volume in trained rowers.