Isokinetic strength and jumping abilities of teenage soccer players playing in different field positions

Soccer is a sport being performed in a very dynamic manner. It requires soccer players to be able to develop high muscle force in a very short period of time. The aim of the study was to evaluate the strength and jumping abilities of young soccer players playing in different positions on the field. The study included 49 adolescent soccer players: 6 goalkeepers, 15 defenders, 17 midfielders and 11 strikers. We measured peak torques (PT), total work (TW), and average power (AP) developed by the knee flexors and extensors under isokinetic conditions at angular velocities of 60°⋅s^–1, 180°⋅s^–1 and 300°⋅s^–1 on a Biodex dynamometer, and jump height (H) and maximum power (P_max) on a force plate. PT, AP, TW, and P_max scores were normalized relative to body mass. There were no statistically significant differences between measurements of basic somatic characteristics (body height and body weight), age and biological age as well as PT, AP, TW, H, and P_max in players from different positions on the field. Unlike defenders, midfielders showed a significant correlation of isokinetic tests indices with jump height (r = 0.54÷0.84) and maximum relative power (r = 0.55÷0.76). The differences in correlations are probably due to the different tasks and activities that players in different positions on the field perform during the game.