Ruf, L, Chéry, C, Taylor, KL. Validity and reliability of the load-velocity relationship to predict the 1RM in deadlift. J Strength Cond Res 32(3): 681-689, 2018-The aim of this study was to verify the reliability and validity of using submaximal loads from the load-velocity relationship to predict the actual 1 repetition maximum (1RM) in the deadlift. Data from 11 resistance-trained athletes were analyzed performing three 1RM assessments separated by at least 3 days. Reliability was assessed by comparing predicted 1RMs of sessions 2 and 3, whereas for validity purposes, predicted 1RMs of session 3 were compared with actual 1RMs of session 2. Mean concentric velocity at 1RM (v at 1RM) was entered in individualized linear regression equations, derived from the load-velocity relationship for 3 (20-60%, 40-80%, and 60-90% of 1RM), 4 (20-80% and 40-90% of 1RM), and 5 (20-90% of 1RM) incremental loads to predict 1RMs. There were trivial changes for all predicted 1RMs between sessions with 20-90% of 1RM being the most reliable model. Similarly, the actual 1RM was very stable (effect size [ES] = 0.04, 90% confidence limit [CL] [-0.03 to 0.12], typical error of measurement [TE] = 3.4 kg [2.5-5.4], intraclass coefficient [ICC] = 0.99 [0.96-0.996], and coefficient of variation [CV] = 1.9% [1.4-3.0]), whereas the v at 1RM was unreliable between trials (ES = -0.30, 90% CL [-0.78 to 0.17], TE = 0.029 m·s [0.022-0.047], ICC = 0.63 [0.19-0.86], and CV = 15.7% [11.7-26.1]). However, predicted 1RMs computed from all submaximal load ranges substantially overestimated the actual 1RM with considerable differences between athletes. Although 1RM predictions showed high reliability, they all overestimated the actual 1RM, which was stable between sessions. Therefore, it is not recommended to apply the prediction models used in this study to compute daily 1RMs.

Chéry, C and Ruf, L. Reliability of the load-velocity relationship and validity of the PUSH to measure velocity in the deadlift. J Strength Cond Res 33(9): 2370–2380, 2019—This study investigated the reliability between load and mean velocity, mean propulsive velocity, peak velocity, mean power, and peak power in the deadlift. Also, we looked at the validity of an inertial sensor (PUSH) and a linear-position transducer (Tendo) to measure velocity variables. Ten strength-trained men (23.4 ± 1.3 years) were involved in three 1 repetition maximum (1RM) testing sessions, separated by at least 72 hours. The protocol used 6 different lifting intensities, comprising 20, 40, 60, 80, 90, and 100% of 1RM. Reliability of the load-velocity and load-power relationship was assessed by comparing velocity and power measurements from session 2 and 3 for each relative %1RM. The validity of tested devices was analyzed regarding to each relative intensity by comparing results from each instrument to a reference instrument (GymAware). The findings revealed that intermediate intensities (ranging from 60 to 90% of 1RM) seem to be reliable. Furthermore, extreme points of the load-velocity curve (20, 40, and 100% of 1RM) were found to be less reliable and should therefore be used with caution when implemented as part of autoregulating strategies. Tendo produced measurements that were highly correlated with GymAware and thus, constitutes a valid and cheaper alternative. By contrast, measurements from the PUSH presented a low level of precision and accuracy. Therefore, PUSH cannot be considered as a valid tool to measure velocity variables in the deadlift.