Exploring the Y-Balance-Test scores and inter-limb asymmetry in soccer players: differences between competitive level and field positions

Background: The postural stability seems to be important in the physical development of the soccer player and the specific tasks related to the game. In addition, it is related to the injury risk and therefore, with the injury prevention and retraining processes. In this context, the Y Balance Test (YBT) is presented as a tool to assess dynamic postural control. Objective: This study aimed to explore the differences and possible correlations in the YBT scores and inter-limb asymmetry for anterior (ANT), posteromedial (PM) and posterolateral (PL) directions by category and field position in soccer players. Methods: 173 males soccer players aged between 14 and 33 years old agreed to participate. Five categories and six field position were considered in this study. A standardised protocol was used at multiple clubs during the pre-season assessment of musculoskeletal function in soccer players. All the players performed the Y Balance Test (YBT) (official YBT Kit), assessing the dominant and non-dominant leg for three YBT directions (anterior-AN, posteromedial-PM and posterolateral-PL), inter-limb asymmetry and composite score. Results: For AN, amateur and semiprofessional obtained the highest values for Dominant and Non-Dominant legs (Range(mean) = 101.8-109.4%) and the lowest level in PRO players (mean: 62.0%). Concerning PM-PL, semiprofessional (Range(mean) = 126.4-132.7%, dominant and non-Dominant respectively), followed by professional and amateur reported higher scores compared to youth categories. Inter-limb asymmetry showed higher values in lower age categories. The best composite scores were detected in semiprofessionals (Range(mean) = 113.3-126.7% for dominant and Range(mean) = 113.8-129.7% for non-Dominant leg), compared with the rest of the categories and for each field position evaluated. Conclusion: Comparisons between field-positions revealed that centre-backs were worse than wingers and forwards. In order to explain variations in dynamic balance between competitive levels within the same age-group, special considerations about training programmes and related co-variables should be considered.