(7) THE DIFFERENCES BETWEEN LINEAR POSITION TRANSDUCER ESTIMATED AND ACTUAL ONE-REPETITION MAXIMUM BACK SQUAT

Purpose: The purpose of this study was to assess the differences between the estimated one repetition maximum (1RM) back squat from two different linear position transducers with the actual 1RM. Methods: 14 resistance-trained men (age = 26.0 ± 4.7 years, height = 175.0 ± 7.6 cm, body mass = 89.7 ± 16.1 kg, relative 1RM back squat = 2.1 ± 0.3 kg/kg) participated in this study. Each subject attended a single testing session in which they completed a 1RM back squat test with two linear position transducers (Tendo Power Analyzer [TENDO] and GymAware Powertool [GA]) attached to the same sleeve of the barbell. As a part of the 1RM protocol, each subject was asked to provide a self-estimated 1RM to determine their back squat warm-up loads. The warm-up protocol for the back squat consisted of 5 repetitions at 30%, 5 at 50%, 3 at 70% and 1 at 90%. Once the warm-up was completed, the subjects performed 1RM attempts and their maximal load was determined within five or fewer repetitions. The average mean (MBV) and peak (PBV) barbell velocities produced during each warm-up set were collected from both the TENDO and GA and used to develop individual load-velocity profiles. Linear regression equations (y = mx+b) were then used to estimate the 1RM back squat. The estimated 1RM from the linear position transducers and actual 1RM were compared using a one-way repeated measures ANOVA with Bonferroni post hoc tests. In addition, Hedge’s g effects sizes were used to determine the magnitude of differences between the estimated 1RMs and actual 1RM. Results: Estimated and actual 1RM descriptive data are displayed in Table 1. There was a significant difference between the estimated 1RMs and the actual 1RM (p = 0.049). The Bonferroni post hoc analyses showed significant differences between the estimated 1RMs from TENDO MBV (p = 0.006, g = 0.73) and GA MBV (p = 0.004, g = 0.75) and the actual 1RM. In contrast, there was no significant differences between the estimated 1RM from TENDO PBV (p = 0.410, g = 0.59) or GA PBV (p = 0.335, g = 0.58) and actual 1RM. Conclusions: There were significant, moderate differences between estimated 1RM from TENDO and GA MBV and the actual 1RM back squat. In contrast, the differences between estimated 1RM from TENDO and GA PBV were small and non-significant. Linear position transducers may produce a larger variation in estimated 1RM with PBV equations compared to MBV equations and actual 1RM. Practical Applications: The use of linear position transducers to estimate 1RM back squat performance may be questioned due to the considerable variability of the data which may prevent accurate load assessment and prescription, as well as the ability to track maximal strength progression. Acknowledgements: None.