Relationship of Initial and Maximal Isometric Torque with Jumping Ability Characteristics in Young Female Volleyball Players

Elissavet N. Rousanoglou & Konstantinos D. Boudolos

Sports Biomechanics Lab

Department of Physical Education & Sport Science, National and Kapodistrian University of Athens, Hellas

Abstract

The purpose of the study was to investigate whether the different type of jumping test determines the significance of the relationships between the isometric torque (TISOM) and the mechanical characteristics of jumping ability. Twenty one elite young female volleyball players (14-19 yrs), with equivalent representation of the two competitive age categories (girls – young women) participated in the study. The mechanical characteristics of jumping ability (jump height, maximal power and maximal impulse) were measured with a forceplate (Kistler, Type: 9286AA) in two jumping tests (CMJ and SJ) that distinctly differ with regard to the use or no use of the stretch–shortening cycle. The TISOM of the knee extensors (60ο) was measured in the initial phase of muscle con- traction at the first 300 ms (TIN) and at the maximal value (TMAX), with the isokinetic dynamometer Cybex ΙΙ+. The results showed that, with the exception of TMAX (p<.05), the two age categories had no significant difference in the examined characteristics (p>.05). For the total sample, the relationships of TIΝ and TΜΑΧ were strong with jump height in CMJ (r=.72 and r=.72, respectively, p<.05) but not with jump height in SJ (p>.05). In comparison to jump height, the maximal impulse had a weaker relationship with TIΝ and TΜΑΧ (r=.66 and r=.696, respectively, p<.05) and it was highlighted as a more determinative measure than maximal power (r=.50 and r=.53, respec- tively, p<.05). In the direction of a rationalistic test selection for the evaluation of high level athletes, under similar conditions, it is suggested to combine phases of isometric muscle contraction that correspond to the critical times of competitive action, as well as jumping tests that best simulate the competitive motor patterns.