Variability in Back Squat Repetitions Performed Before Exceeding Different Velocity Loss Thresholds

Abstract

This study aimed to evaluate the intra-individual between-day variability in the number of repetitions performed before exceeding 10%, 20%, and 30% velocity loss thresholds (VLTs) during the back squat exercise. Thirty resistance-trained male wrestlers performed sets of repetitions to failure at 70% and 80% of their 1-repetition maximum (1RM) on two separate days. Velocity loss was calculated using as the reference either the first repetition of the set or the fastest repetition. The set termination criterion specified stopping the set after one or two consecutive repetitions exceeded the prescribed VLT. Variability in repetitions was expressed as the coefficient of variation (CV), calculated as the absolute difference between sessions divided by the average repetitions across sessions. All factors, including load (70%1RM vs. 80%1RM), reference repetition (first repetition vs. fastest repetition), and set termination criterion (one vs. two repetitions exceeding the VLT), significantly affected the number of repetitions performed for the 10%, 20%, and a 30% VLT conditions (p<.01). Regardless of these factors, intra-individual variability in the number of repetitions performed between sessions was consistently high (CV > 10%). These findings highlight two key challenges when using VLTs in training prescription. First, specifying a VLT alone is insufficient, as the actual number of repetitions performed—which ultimately dictates adaptations—is influenced by multiple methodological factors. Second, even when methodological factors are standardized, the inherent variability in the number of repetitions performed across sessions remains high, which could impact acute fatigue responses and longterm training adaptations.