Abstract des Autors

The primary purpose of this study was to examine concurrent validity of the jump-and-reach (JaR) test using the Vertec system and a criterion device (i.e., Optojump system). In separate sub-analyses, we investigated the influence of gym floor condition and athletes' sex on the validity of vertical jump height. Four hundred and forty sub-elite adolescent female (n = 222, mean age: 14 +/- 1 years, age range: 13-15 years) and male (n = 218, mean age: 15 +/- 1 years, age range: 14-16 years) handball players performed the JaR test in gyms with region or point elastic floors. Maximal vertical jump height was simultaneously assessed using the Vertec and the Optojump system. In general, significantly higher jump heights were obtained for the Vertec compared to the Optojump system (11.2 cm, [INCREMENT]31%, Cohen[spacing acute]s d = 2.58). The sub-analyses revealed significantly larger jump heights for the Vertec compared to the Optojump system irrespective of gym floor condition and players' sex. The association between Optojump and Vertec-derived vertical jump height amounted to rP = 0.84, with a coefficient of determination (R2) of 0.71. The sub-analyses indicated significantly larger correlations in males (rP = 0.75, R2 = 0.56) than in females (rP = 0.63, R2 = 0.40). Yet, correlations were not significantly different between region (rP = 0.83, R2 = 0.69) as opposed to point elastic floor (rP = 0.87, R2 = 0.76). Our findings indicate that the two apparatus cannot be used interchangeably. Consequently, gym floor and sex specific regression equations were provided to estimate true (Optojump system) vertical jump height from Vertec-derived data.