THE VALIDITY OF CHRONOJUMP SYSTEM ® TO MEASURE VERTICAL JUMP

Abstract

Several devices have been used to measure vertical jump tests. A force platform (FP) is a standard device for vertical jump measurement since it provides more valuable information beside jump height such as force, rate of force development, ground contact time, etc.; however, the cost of FP is very high. Thus, an alternative device such as a contact mat has been used due to its lower cost. A Chronojump system (CS) is a low cost contact mat which is available with an open-source software. Nevertheless, its validity has not yet been determined; thus, the purpose of this study was to compare jump parameters including flight time (FT) and ground contact time (CT) between CS and a FP. Thirty healthy collegiate male athletes age ranges between 18-25 years old were participated in this study. After warm-up, all athletes performed 4trials of 2 jumps; countermovement jump (CMJ) and drop jump (DJ) trials on a FP which the contact mat was placed on the top. Flight time (FT), contact time (CT) and jump height (JH) were compared using Bland and Altman method. Bland and Altman revealed no significant differences of jump parameters between two devices but CT derived from CS was underestimated as compare to FP. In conclusion, it seems that a contact mat of CS was found to be a valid jump measurement device. However, CT in DJ may need to be interpreted with caution.

Journal of Sports Science and Technology 2018; 18(1) : 8-15

Keywords: Vertical jump height / Force platform / Chronojump / Validity