Technique-Specific Load-Velocity Profiling and Prediction Equation for the Back Squat in Elite Portuguese Rugby...

This study examined whether barbell velocity can accurately predict relative load during a free-weight parallel squat performed with a deliberate pause between the eccentric and concentric phases in elite Portuguese rugby players. A repeated-measures design was used, in which 25 athletes completed an incremental loading protocol up to their one-repetition maximum (1-RM) on two occasions separated by four weeks. The relationship between mean propulsive velocity (MPV) and %1-RM was analyzed using polynomial regression, and a second-order prediction equation was developed. The model showed a very strong association between MPV and %1-RM (R² = 0.95) with a standard error of estimate of 6.27 %1-RM, indicating good practical accuracy. Test-retest analyses demonstrated high stability of the load-velocity relationship (mean velocity difference: -0.01 ± 0.02 m·s^-1). Compared with values reported in other athletic populations, first-division rugby players displayed distinct load-velocity profiles across the full loading spectrum, underscoring the influence of execution technique and population characteristics on load-velocity behavior. These findings support the use of individualized velocity-based prescriptions rather than generalized equations. In conclusion, this study provides a technique- and population-specific prediction equation for the paused parallel back squat, offering a novel and practical tool for regulating training intensity in elite rugby players.