No abstract

The purpose of this study was to examine the reliability of load-velocity profiles (LVPs) and validity of 1-repetition maximum (1-RM) prediction methods in the back-squat using the novel Vitruve linear position transducer (LPT). Twenty-five men completed a back-squat 1-RM assessment followed by 2 LVP trials using five incremental loads (20%–40%–60%–80%–90% 1-RM). Mean propulsive velocity (MPV), mean velocity (MV) and peak velocity (PV) were measured via a (LPT). Linear and polynomial regression models were applied to the data. The reliability and validity criteria were defined a priori as intraclass correlation coefficient (ICC) or Pearson correlation coefficient ( r) > 0.70, coefficient of variation (CV) ≤10%, and effect size ( ES) <0.60. Bland-Altman analysis and heteroscedasticity of errors ( r2) were also assessed. The main findings indicated MPV, MV and PV were reliable across 20%–90% 1-RM (CV < 8.8%). The secondary findings inferred all prediction models had acceptable reliability (CV < 8.0%). While the MPV linear and MV linear models demonstrated the best estimation of 1-RM (CV < 5.9%), all prediction models displayed unacceptable validity and a tendency to overestimate or underestimate 1-RM. Mean systematic bias (−7.29 to 2.83 kg) was detected for all prediction models, along with little to no heteroscedasticity of errors for linear ( r2 < 0.04) and polynomial models ( r2 < 0.08). Furthermore, all 1-RM estimations were significantly different from each other ( p < 0.03). Concludingly, MPV, MV and PV can provide reliable LVPs and repeatable 1-RM predictions. However, prediction methods may not be sensitive enough to replace direct assessment of 1-RM. Polynomial regression is not suitable for 1-RM prediction.

The purpose of this meta-analysis was to synthesize the literature and provide a robust estimate of the correlations between lower-body, multijoint, isometric and dynamic neuromuscular assessment variables and snatch (SN) and clean and jerk (C&J) performance in competitive weightlifters. A comprehensive search through 3 electronic databases (PubMed, SPORTDiscus, and Web of Science) returned 12 studies that met the inclusion criteria. Meta-analyses were performed on Pearson's correlations between SN and C&J performance and 15 variables from 5 neuromuscular assessments—countermovement jump (CMJ), squat jump (SJ), isometric midthigh pull (IMTP), back squat (BS), and front squat (FS) one repetition maximum (1RM). The FS and BS 1RM exhibited nearly perfect correlations (r = 0.93 to 0.94), whereas the IMTP peak force exhibited very large correlations (r = 0.83 to 0.85). The IMTP force at 250 ms exhibited very large correlations (r = 0.77 to 0.78), and the CMJ and SJ peak power exhibited very large to nearly perfect correlations (r = 0.88 to 0.92). These findings illustrate the importance of lower-body maximal and time-limited force-producing capabilities in weightlifters. Moreover, each assessment offers at least one variable that exhibits a correlation of >0.70. Therefore, these assessments may be used to gauge weightlifting performance potential.

This study examined the test re-test, intrarater and interrater reliability of joint kinematics from the coach's Eye smartphone application. Twenty-two males completed a 1-repetition maximum (1-rM) assessment followed by 2 identical sessions using 5 incremental loads (20, 40, 60, 80, 90% 1-rM). Peak flexion angles at the hip, knee, and ankle joints were assessed using 1 experienced practitioner and 1 inexperienced practitioner. the acceptable reliability thresholds were defined as intraclass correlation coefficient (Icc) r > 0.70 and coefficient of variation cv ≤ 10%. the test re-test reliability of peak hip and knee flexion were reliable across 20-90% 1-rM (r > 0.64; cv < 4.2%), whereas peak ankle flexion was not reliable at any loaded condition (r > 0.70; cv < 20.4%). no significant differences were detected between trials (p > 0.11). the intrarater reliability was near perfect (r > 0.90) except for peak ankle flexion (r > 0.85). the interrater reliability was nearly perfect (r > 0.91) except for hip flexion at 80% 1-rM and ankle flexion at 20% (r > 0.77). concludingly, the coach's Eye application can produce repeatable assessments of joint kinematics using either a single examiner or 2 examiners, regardless of experience level. the coach's Eye can accurately monitor squat depth.