Validity and usability of a new system for measuring and monitoring variations in vertical jump performance

Vertical jump height (VJ) is one of the most sensitive measures to quantify training-related fatigue and athletic performance in elite athletes. Currently, however, there is no equipment designed to graphically deliver the daily performance changes in VJ compared with the smallest worthwhile change (SWC), which is considered essential in “progressive statistics” to judge meaningful performance fluctuations. The aims of the study were to analyze the criterion validity of a new contact mat (i.e., Elite Jump®), alongside testing its usability to detect meaningful changes in VJ of elite team sport athletes. Thirty-one athletes participated in the criterion validity part of the study while 17 rugby players participated in the VJ sensitivity part. When compared to the force plate, the contact mat produced squat jump (SJ) and countermovement jump (CMJ) values with very high intraclass correlation coefficients (0.998 and 0.997, respectively) and very low biases (-0.11 and -0.08 cm, respectively), as assessed by the Bland-Altman plot. In addition, during a training microcycle, rugby players presented identical meaningful changes in performance in both SJ and CMJ when comparing the Elite Jump® and Hopkins’ spreadsheet outputs. Therefore, the contact mat is valid and the proprietary software can properly execute the SWC calculations, providing coaches and researchers with accurate information concerning variations in the physical performance of elite athletes.