@article{2985545,
    title = "Knee flexion and extension strength in young Brazilian soccer players: The effect of age and position",
    author = "Herdy, C.V. and Galvao, P. and Costa, G.S.E. and Ramos, S. and Simao, R. and Pedrinelli, A. and Mansur, S. and Goncalves, D. and Paschalis, V.",
    journal = "Human movement science",
    year = "2018",
    volume = "19",
    number = "3",
    pages = "23-29",
    publisher = "Sciendo",
    issn = "0167-9457",
    doi = "10.5114/hm.2018.76076",
    abstract = "Purpose: To compare isokinetic knee flexors and extensors concentric muscle strength in young soccer players of different ages and playing positions. Methods: Seventy-seven young male soccer players were divided into 3 age categories: U-15, U-17, and U-20, with the consideration of 4 game positions: goalkeepers, defenders, midfielders, and forwards. The concentric tests of the hamstrings (Hcon) and quadriceps (Qcon) were performed at 30°/s, 60°/s, and 180°/s, and the ratio of 180°/30° was calculated. Results: The values of Qcon for the U-15 turned out significantly lower in comparison with the U-20 in 30°/s and 180°/s and in the 180°/30° ratio. The Hcon values for the U-15 were significantly lower than for the U-20 at 30°/s, 60°/s, 180°/s, as well as in the 180°/30° ratio. Strength levels were shown to be significantly different between the 3 analysed categories. The goalkeepers presented with Qcon and Hcon values significantly higher than the other playing positions, regardless of the angular velocity used. Conclusions: U-15, U-17, and U-20 athletes do not have the same level of strength. The goalkeepers demonstrated high strength values, suggesting the importance of specific training for each game position. © University School of Physical Education in Wroclaw."
}