# Temporal Stability and Practical Relevance of Velocity and Velocity-Loss Perception in Back Squat
## 4 Discussion
### Vscore and Velocity-Loss Perception  
This was the first study to investigate the consistency of PVL over four weeks. No significant differences in the Vscore were found pre and post the four-week period indicating PVL as stable for at least this time frame. Regarding the level and characteristics of PVL accuracy, some incongruences with previous studies have been found. It is important to note that this study is the first to use such an extended familiarization period before assessing PVL accuracy. In previous research, two studies provided no familiarization at all [15; 18], and others performed only a single session [21; 24]. Based on our results PVL appears to be primarily influenced by the %VL threshold, with higher thresholds corresponding to increased accuracy. The highest PVL accuracy was observed at the 40% VL threshold with the heaviest load (80% 1 RM), where no participant exceeded a one-repetition error even after 4 weeks. Additionally, the \(\mid\)Vscore \(\mid\) for 40% VL at 60% 1 RM had an error comparable to that for 20% VL at 80% 1 RM. However, these results appear to be in contrast with findings from other studies that reported that an increase in repetitions performed, therefore in %VL is associated with a higher PVL error [20; 21; 22]. [PERSON] et al. hypothesized two pathways responsible for this [21]: (1) the time delay after the initial repetition may cause the sensation of velocity perceived during that first attempt to fade, potentially altering PVL, and (2) neuromuscular fatigue, which could lead to discomfort and hinder participants' ability to perceive velocity. However, our results do not support these hypotheses, as sets with higher %VL turned out to be more precise. We hypothesize that multiple factors may underlie these results. Firstly, two of the previously reviewed studies assessed a parameter that differs slightly from PVL, as those studies focused on the perception of changes in velocity, specifically, verbally reporting the velocity of each repetition [20; 22]. Consequently, they did not evaluate the accuracy in identifying the attainment of a specific VL threshold, but rather the ability to perceive variations in repetition velocity within a set. In our view, perceiving the velocity of the final repetition is fundamentally different from recognizing the sensation associated with reaching a given percentage of velocity loss. This distinction may explain the discrepancies between our findings and those of earlier investigations. Furthermore, we suggest that during the familiarization sessions, participants may have begun associating specific %VL thresholds with distinct sensations of fatigue and proximity to momentary failure. Therefore, while [PERSON] et al. hypothesized that PVL accuracy deteriorates over time due to the increasing temporal and mechanical separation between the first and last repetitions, our findings indicate the opposite trend: as the number of repetitions increases (i.e., higher %VL), accuracy improves, possibly because participants are progressively approaching failure. This interpretation is supported by evidence from previous research on repetitions in reserve (RIR), which shows that the closer individuals are to failure, the more accurate their RIR estimations tend to be [31]. Consequently, the 40% VL threshold at 80% 1 RM yielded the highest precision and proximity to failure compared to other load and %VL combinations. Regarding the importance of load in PVL, results in the literature are conflicting [21,24]. [PERSON] et al. [24] found higher accuracy with heavy loads compared to lower ones. On the other hand, [PERSON] et al. [21], found that PVL was more accurate with loads between 50 and 60% of 1 RM compared to heavier ones [21]. The present investigation shows only a trend (\(p=0.06\)) in line with the result of [PERSON] et al. [24]. Therefore, based on these results, it seems that PVL is a reliable parameter, also stable over time.