BIOMECHANICAL JUMP CHARACTERISTICS OF CHILDREN (9 - 12 YEARS) BASEBALL PLAYERS AFTER STRETCHING PROGRAM

ABSTRACT The correlation of lower extremity technique with upper extremity performance of adolescent baseball players is essential for the overall sporting achievement. The purpose of this study was to estimate and compare the important biomechanical jump characteristics of children (9-12-year-old) baseball players (n=14) with control children group (n=17) at the same age. Chronojump contact platform, detecting a single jump with one phase of flight, was used to evaluate five important biomechanical jump characteristics – jump height at squat, countermovement and Abalakov jumps, lower limb elasticity index (IE) and use of arms index (AUI). The results obtained showed statistically significant elevation of jump height in the three jumps used at baseball team. Interesting tendencies were received for the other two calculated indices as well. The lack of statistically significant difference for the IE allows us to suggest an increase of the duration, frequency, and number of stretching exercises in the athletes training program. This would increase the lower limbs elasticity index and will improve force increment due to the elastic energy accumulated during the shortening-stretching cycle. The trend for AUI index is elevated in the control group relative to the team. In addition, the presented data draw attention to improving coordination between the lower and upper body, emphasizing the individual characteristics of each athlete. From the presented relations it is clear that the excellent sports achievement is a result from the complete set of all factors that determine it. However, a more comprehensive analysis, using similar biomechanical methods, is needed for a complete comparison.