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.