“Which autoregulation strategy should we use?” The effects of velocity loss thresholds on RPE and their individual differences in the back squat

Velocity loss thresholds (VLT) and rating of perceived exertion (RPE) are two autoregulatory (AR) methods often implemented in resistance training. To provide coaches with a clearer understanding of the interplay of the two different methods, the aim of this study was to investigate the effects of 10%, 20%, 30% and 40% VLTs on RPE and repetition characteristics during the back squat exercise. 17 resistance-trained males performed one repetition max (1RM) back squat testing to determine individual load-velocity profiles. In a subsequent session, subjects completed sets to failure at 85% 1RM with 10%, 20%, 30%, and 40% VLTs. Kinematic outputs were measured with a linear position transducer, and RPE was recorded after each set. Significance was set at p < 0.05. Linear mixed models revealed significant effects of VLT on RPE and repetitions, with analyses demonstrating that RPE was significantly higher at greater VLT. Additionally, there was substantial inter-subject variability in the number of repetitions completed at each threshold. Collectively, these findings demonstrate that VLT significantly influence both perceived exertion and repetition characteristics and can help regulate the proximity to failure and exertion of athletes. Furthermore, the heterogenous response of RPE and repetitions between subjects suggests that VLT may induce varying levels of perceived exertion and repetition totals. This may be due to individual factors such as muscular endurance and ability to gauge exertion. Thus, AR prescriptive methods (e.g., RPE or VLT) should be used alongside traditional prescriptive methods to guide training and support the adjustment of training loads and volume.