The effect of the stretch-shortening cycle movement pattern and its relationship with primary performance indicators in Rugby Union

Abstract

The primary objective of the study is to investigate the relationship of the Stretch Shortening Cycle with primary performance indicators for rugby union, and to determine the physiological differences between forwards and backs. A total of 20 (forwards, n=10; backs, n=10) trained semi-professional rugby union males aged between 19 – 22 years were analysed as a combined group (Group 1), and as two separate groups (Forwards = Group 2; Backs = Group 3). Each subject underwent physiological measurements of height, body mass, muscular power (Vertical Jumping for height, using a Squat Jump, Countermovement Jump, and a 5 Bound Jump for height with minimum ground contact time), speed (10m and 40m), and leg strength (5RM Squat). Forwards were taller and heavier than backs (184.7 ± 10.9cm and 107.5 ± 18.9kg vs 180.6 ± 5.6cm and 88.5 ± 5.9kg) but were shown to be significantly slower over the 10m and 40m sprint distances (p<0.05) which can be reflected by the significant difference in jump height ability between forwards and backs (p<0.05; Forwards SJ and CMJ: 33.53 ± 2.98cm and 35.68 ± 3.62cm vs Backs: 40.33 ± 7.45cm and 42.65 ± 7.44cm). SJ and CMJ were significantly related to sprint performance in the whole group analysis (p<0.05, SJ – 10m and 40m: r – 0.74 and r – 0.77; CMJ – 10m and 40m: r – 0.74 and r – 0.76). Scores for 5BJ and Sprint Performance were not significantly related, although there was a significant difference between forwards and backs for the 5BJ test, and Squatting for absolute leg strength did not significantly related to any of the measured variables. There were no significant differences (p>0.05) evident between forwards and backs’ squatting ability. Results show that jumping ability reflects performance in sprint running, and physiological characteristics can determine an individuals role within the game. There is no direct effect between leg strength and sprint running, however and increase in the ability to produce a higher force can effect an improvement in other variables which are related to sprint performance. These finding provide performance standards for sub-elite trained athletes.