Characteristics of physical fitness for javelin throwers focusing on the ability to achieve ballistic stretch-shortening cycle movement of the lower limbs

Abstract

A study was conducted to investigate the characteristics of physical fitness for javelin throwers focusing on the ability to achieve ballistic stretch-shortening cycle (SSC) movement of the lower limbs. Fourteen javelin throwers (JT), ten other throwers (OT) and twelve jumpers (J) performed rebound drop jumps (RDJ) from a box with a height of 0.3 m. The ability to achieve ballistic SSC movement was evaluated using the RDJ index proposed by Zushi et al. (1993). The RDJ index was calculated using the formula [RDJ index=(1/8・g・Ta^2)/Tc], where g is 9.81m/s2, and Ta and Tc are air time and contact time in RDJ, respectively. The results were as follows: 1) RDJ-index in JT was significant lower than that in J, but significantly higher than that in OT. 2) Contact time in JT was similar to J, and air time in JT was similar to OT. 3) Although there was no significant correlation between javelin throw record and contact time (r=-0.270, ns), there were significant correlations between javelin throw record and air time (r=0.620, p<0.05), and RDJ index (r=0.692, p<0.01). These findings suggest that the ability to achieve ballistic SSC movement of the lower limbs in javelin throwers is ranked between jumpers and other throwers, and that explosive power evaluated by the RDJ index may be required in order to improve the performance of a javelin thrower.