engleski

The use of reactive strenght index to evaluate unilateral horizontal drop jump performance in children

Jumping is one of the most important abilities for success in many sports. Stretch-shortening cycle (SSC) is being used in order to perform jump. To measure jumping performance or to control effects of some program, scientists and practitioners usually use Standing long jump (SLJ), Squat jump (SJ), Countermovement jump (CMJ) or vertical Drop jump (DJ) and variations. Recently, the reactive strength index (RSI) in practical as well as in exercise science literature is used as a means to quantify plyometric or SSC. Therefore, the aim of this study was to investigate the relationship between RSI and unilateral drop jump performance (jump distance) in children (male and female). Secondary goal was to investigate correlations between other kinetic variables in SSC drop jump movement as the amount of force (eccentric and concentric) as well as the rate of force development (RFD) and overall performance measured in jump distance. Divided in three groups (male, female and both), results showed no significant difference between male and female children in all variables (p level from 0, 11 to 0, 62). Male children have greater jump distance than female (225, 49 vs 213, 76cm), but difference was not significant (p=0, 23). RSI (reactive strength index) is statistically significant (0, 60), correlated to jump distance with both male and female, and maximum concentric force (FmaxCON) is also significantly correlated to jump distance, but only in male participants. Inverse correlation was found between jump distance and contact time in male participants (-0, 05). These findings can be useful in further investigations on SSC movement mechanism. The use of RSI during fast plyometric exercises is an effective application of the performance measure and can enhance the quality of training.

plyometrics, ground reaction force, rate of force development, stretch-shortening cycle

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