Bilateral isokinetic concentric and eccentric strength profiles of the knee extensors and flexors in young soccer players

• Published in: Isokinetics and exercise science 2001-01, Vol.9 (1), p.31-39
• Main Authors: KELLIS, Spiros, GERODIMOS, Vasilios, KELLIS, Eleftherios, MANOU, Vasiliki
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 0959-3020; 1878-5913
• DOI: 10.3233/ies-2001-0061

Isokinetic dynamometers are extensively used to monitor strength development in young soccer players. The purpose of this study was to examine the effects of age, velocity and leg of preference on the peak moments in young soccer players. One hundred and fifty eight soccer players (age = 13.2 plus or minus 2.1 years; height = 1.6 plus or minus 1.4; body mass = 51.6 plus or minus 14.89 kg) performed maximum knee extension and flexion efforts at 30 degree /s, 90 degree /s, 120 degree /s and 180 degree /s of both legs and under eccentric and concentric conditions. The absolute (Nm) and the relative (Nm/Kg) peak moment of forces were further analyzed. Four-way analysis of variance designs were applied to examine the effects of age, angular velocity, leg of preference and muscle action (eccentric - concentric) on the recorded moments for knee extension and flexion. The isokinetic moment of force of knee extensors ranged from 1.01 plus or minus 0.19 to 3.58 plus or minus 0.50 Nm/kg. The knee flexion moments ranged from 0.95 plus or minus 0.16 Nm/kg to 2.42 plus or minus 0.59 Nm/kg. For all testing conditions eccentric moments were greater than the corresponding concentric (p < 0.05). The isokinetic moment under all testing conditions increased significantly (p < 0.05) as chronological age increased from 10 to 18 years. Furthermore, the isokinetic moment of the preferred leg, collapsed for the effects of age, angular velocity and muscle action, was significantly greater compared to the moments of the other leg. The strength profiles developed in the present study can assist in the establishment of baseline data in young soccer players.