Velocity-Based Monitoring Lacks Both Accuracy and Applicability for Estimating Repetitions in Reserve During the Hexagonal Bar Deadlift

ABSTRACT: Chen, W, Zhang, H, Li, R, Chen, Z, Zheng, J, Zhang, X, and Li, Z. Velocity-based monitoring lacks both accuracy and applicability for estimating repetitions in reserve during the hexagonal bar deadlift. J Strength Cond Res XX(X): 000-000, 2026-This study evaluated the accuracy and applicability of using barbell mean velocity (MV) to predict repetitions in reserve (RIR) in the hexagonal bar deadlift (HBD). After RIR-MV relationship modeling, 19 well-trained males completed 2 randomized sessions consisting of 4 sets to failure at either 65% or 85% of their 1-repetition maximum load. Methodological accuracy and applicability were rigorously defined by 3 concurrent criteria: a median absolute error ≤2 repetitions, and a minimum probability of 75% for both acceptable estimation (absolute error ≤2 repetitions) and the occurrence of expected velocity thresholds (i.e., the probability that the target RIR-specific MV actually manifests). Our results demonstrate that no experimental condition successfully satisfied all 3 criteria. Predictive performance was significantly compromised by load intensity, the RIR-MV relationship model, and the set number. Crucially, the low probability of threshold occurrence across most conditions renders these models functionally obsolete for real-time monitoring. Therefore, despite the prevalence of velocity-based training, the RIR-MV relationship lacks the requisite precision and reliability for monitoring HBD training. Practitioners should exercise caution when applying general or even individual velocity thresholds to HBD.