Background and Objectives: The purpose of this study was twofold: (1) to examine strength asymmetries in elite athletes of different sports and (2) to examine the magnitude of asymmetries between elite and u18 athletes. Materials and Methods: A total of 254 athletes participated in this study. For the first purpose of the study, the group consisted of adult professional male basketball players (n = 30), elite male (n = 30) and female soccer players (n = 20), male futsal players (n = 30), elite male goalkeepers (n = 22), and professional female volleyball players (n = 20). For the second purpose, male youth goalkeepers (n = 22), youth female (n = 20) and male soccer players (n = 30), and youth male basketball players (n = 30) were compared to the adult athletes of the same sport. Asymmetries were measured utilizing a Humac Norm and Rehabilitation device. Testing included three maximal concentric flexion and extension repetitions at an angular speed of 60°/s. The differences in asymmetries were assessed using ANOVA followed by an LS means post-hoc analysis. An independent samples t-test was used to identify the differences between adult and youth players. Results: It was indicated that none of the groups demonstrated asymmetries greater than 10%, other than the elite female soccer players and female volleyball players. Significant differences were demonstrated between youth and adult soccer players (males and females), with the adult groups demonstrating increased asymmetries. Conclusions: Special consideration should be given to female soccer players and volleyball players, as soccer and volleyball practice and competition at the professional level may induce greater lower -limb asymmetries. The isokinetic parameters can be useful for planning strength and conditioning interventions in order to reduce or prevent those imbalances. Additional unilateral and bilateral jumping testing is encouraged for the verification of imbalances.
Keywords: bilateral asymmetry; imbalance; sports; unilateral asymmetry.