Reliability Of Common Movement Screens On Commercial Uniaxial Force Plates And Software

Commercial force plates and software have increased in popularity as a human performance and injury risk screening tool in athletes and tactical personnel. Common assessments include the squat, Abalokov jump (ABJ), and isometric mid-thigh pull (IMTP). It has been further suggested that upper body performance can be derived from a plyometric push up (PPU) using the countermovement jump (CMJ) software protocol, however, there have been concerns about the validity of this method. PURPOSE: Examine the test-retest reliability of the squat, ABJ, IMTP and PPU via a commercial uniaxial force plates and analysis software. METHODS: 44 healthy individuals (Age: 24.3 ± 5.7 yrs, Height: 170 ± 8 cm, Weight: 68.9 ± 11.3 kg, 17 male) performed force plate testing on bilateral force plates on two occasions separated by approximately 4 weeks. Subjects performed 5 reps of the squat and ABJ and 3 reps of the PPU and IMTP. PPU was analyzed using the software protocol for CMJ or general force time analysis (GFTA) when CMJ failed. IMTP variables were extracted from a GFTA. Outcomes were processed exported via proprietary software and analyzed with custom R code. The mean values of all outcomes and the greatest IMTP force were analyzed for Intraclass correlation coefficients (ICCs) and Standard Error of the Measurement. RESULTS: Full results are provided in Table 1. Most outcomes demonstrated good reliability (ICC > 0.90). PPU Peak Force Asymmetry and squat Concentric/Eccentric Peak Force Asymmetry were moderately reliable (ICC 0.75 - 0. 9)1. PPU Peak Power demonstrated poor reliability (ICC = 0.073). CONCLUSION: Common assessments and outcome variables used via commercial force plates and software demonstrate good reliability for most outcomes. Asymmetry values are less reliable than total values. Practitioners monitoring PPU performance should consider direct measurements (i.e., peak force) over calculated measurements like power calculated for CMJ. 1. Bobak CA, et al. 2018 Table 1. - Variable Test n ICC ICC 95%CI SEM Jump Height (cm) ABJ 32 0.986 0.960-0.990 0.692 Peak Vertical Force (N) ABJ 32 0.980 0.893-0.973 0.4945 Peak Force Asymmetry (%) ABJ 32 0.904 0.813-0.952 0.110 Peak Power (W) ABJ 32 0.976 0.951-0.988 7.207 Maximum Force (N) IMTP 41 0.952 0.912-0.974 4.592 Mean Force (N) IMTP 39 0.955 0.917-0.976 4.644 Peak Vertical Force (N) PPU 32 0.989 0.978-0.995 3.288 Peak Force Asymmetry (%) PPU 32 0.715 0.492-0.850 0.207 Peak Power (W)* PPU 10 0.073 -0.553-0.647 9.373 Concentric Peak Force (N) Squat 44 0.956 0.929-0.978 3.321 Eccentric Peak Force (N) Squat 44 0.926 0.878-0.962 3.271 Concentric Peak Force Asymmetry (%) Squat 44 0.738 0.590-0.857 0.125 Eccentric Peak Force Asymmetry (%) Squat 44 0.735 0.582-0.854 0.141 ICC=Intraclass Correlation Coefficient, 95%CI = upper and lower bounds of 95% confidence interval, SEM = standard error of the measurement, ABJ = Abalokov Jump, IMTP=Isometric Mid-Thigh Pull, PPU=Plyometric push up, cm = centimeters, N=Newtons, W=Watts, n = number of participants with valid test-retest data*Power was only derived from the 10 subjects whose PPU tests analyzed successfully using the software CMJ protocol. Force values for the failed analyses were derived from a GFTA. Supported by: Supported by the Office of Naval Research N0004-21-1-2682. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Office of Naval Research, the US Navy, or the US Special Operations Command.