Feldmann, CR, Weiss, LW, Schilling, BK, and Whitehead, PN. Association of drop vertical jump displacement with select performance variables. J Strength Cond Res 26(5): 1215–1225, 2012—Drop vertical jumps (DVJs) stimulate enhanced countermovement loading as would occur with a run-up before jumping. A variety of performance variables have been associated with DVJ performance including ground contact time (GCT), reactive strength index (RSI), eccentric utilization ratio (EUR), and elasticity index (EI). This study examined the stability reliability and precision of these variables and their associations with DVJ displacement in trained men and women. The EUR and EI measures were redundant, so only EUR findings were reported. Except for EUR, data for all variables were both reliable and precise (intraclass correlation coefficient ≥ 0.70, coefficient of variation [CV%] ≤ 15.0) although EUR data were precise (CV% ≤ 15.0). Correlations with DVJ displacement were low for GCT, moderate for RSI, and negligible for EUR. Therefore, GCT and EUR likely represent unique performance characteristics not related to DVJ displacement. Furthermore, the variability in DVJ performance accounted for by RSI may primarily reflect the inclusion of displacement as the numerator in the quotient for calculating it.
Musculoskeletal Dynamics Laboratory, Department of Health and Sport Sciences, The University of Memphis, Memphis, Tennessee
Address correspondence to Christina R. Feldmann, firstname.lastname@example.org.