1 22nd International Conference on Sports Rehabilitation and Traumatology: Football Medicine Strategies for muscle and tendon injuries London, 2013 TITLE: ISOKINETIC TESTING OF ATHLETES BRAZILIAN U17, U20 AND PROFESSIONAL. AUTHORS: HERDY, Carlos 1 ; ALKIMIM, Rodolfo 2 ; SELFE, James 3 ; PEDRINELLI, André 4 AFFILIATION: 1 Club de Regatas Vasco da Gama and Physical Education Post-Graduation Program, Federal University of Rio de Janeiro - Rio de Janeiro - Brazil. 2 Brazilian Olympic Committee and Brazilian Football Confederation - Rio de Janeiro - Brazil. 3 School of Sport, Tourism and The Outdoors, University of Central Lancashire, Preston, PR1 2HE, UK 4 Institute of Orthopedics and Traumatology, Hospital das Clinicas, Faculty of Medicine, University of Sao Paulo - Sao Paulo - Brazil. Introduction And Purpose The indices of injuries resulting from soccer practice, due to muscle imbalances, has caused concern for athletes at various ages (5). Normally, there are two physical factors that occur in athletes footballers tend to cause injury. The first is an imbalance between the muscles of the quadriceps and hamstring muscles of the same limb and the second is an imbalance of strength between the dominant and non-dominant limb (5,7). These imbalances have been identified as a common occurrence induced by training footballers, athletes have constantly due to the dynamic equilibrium that currently perform jumps and kicks, suggesting that this factor would increase the risk of injury (1,4,6 ). Therefore, the objective of this study was to compare the values of muscle torque of extensors / knee flexors of the dominant and non-dominant, and evaluate the reason quadriceps / hamstrings (I / Q) and bilateral in categories sub 17, sub 20 and professional. Methods Reviewed an elite group of football players in three different age categories under 17, under 20 and professional members of the club's first division Brazilian league soccer. Was used to assess muscle strength isokinetic computerized equipment Technogym ® brand, model REV9000 in angular velocity of 60 ° / s with five (5) maximum repetitions in concentric contractions. The level of significance was p <0.05. Results Table 1 - Average torque between the categories U17, U20 and professional. Aveƌage toƌƋue ;Nm·kg−1 BWͿ Under 17 Under 20 Professional Dominant quadriceps 240,9 ± 34,3 249,6 ± 37,2 248,5 ± 44,3 Dominant hamstring 136,1 ± 22,2 * 153,1 ± 34,9 157,2 ± 44,4 * Non-dominant quadríceps 235,6 ± 26,3 263,1 ± 38,0 250,6 ± 46,4 Non-dominant hamstring 128,6 ± 23,4 ** 147,9 ± 28,6 148,4 ± 39,4 ** p*: p = 0,021 Dominant hamstring U17/Professional p**: p = 0,021 Non-dominant hamstring U17/Professional