Evaluating the Field 2-Point Method for the Relative Load-Velocity Relationship Monitoring in Free-Weight Back Squats.

Abstract

This study investigated the between-session variability and concurrent validity of the relative load-velocity relationship obtained from different methods during the free-weight back squat. In counterbalanced order, 39 resistance-trained male participants performed two sessions with six different loads (i.e., a multiple-point test) and two sessions with two different loads (i.e., a 2-point test) followed by the actual one-repetition maximum (1RM) attempts. The mean velocity (MV) corresponding to various %1RMs (at every 5% interval from 40 to 90%1RM) was determined through individualized linear regression models using three methods: (i) multiple-point: data of ~40, 50, 60, 70, 80, and 90%1RM from the multiple-point test, (ii) non-field 2-point: data of the lightest and heaviest loads from the multiple-point test, and (iii) field 2-point: data of ~40 and 90%1RM from the 2-point test. The main findings revealed that the between-session variability of the MVs derived from the %1RM-MV relationships was low (absolute differences = 0.02‒0.03 m•s^-1) and similar (p = 0.074‒0.866) across the three methods. Additionally, when compared to the multiple-point method, both the non-field and field 2-point methods showed high correlations (pooled r across all %1RMs = 0.95 ± 0.01 and 0.72 ± 0.09, respectively) and small systematic biases (ranging from -0.01 to 0.01 m•s^-1). Therefore, we recommend that strength and conditioning practitioners use the %1RM-MV relationship, modeled by the field 2-point method, as a quicker and fatigue-free procedure for prescribing the relative load during the free-weight back squat. Specifically, a light load near 40%1RM and a heavy load near 90%1RM are suggested for this method.