The efficacy of lower limb screening tests in predicting PlayerLoad within a professional soccer academy

Context: Training exposure has been associated with injury epidemiology in elite youth soccer, where lower limb musculoskeletal screening is commonly used to highlight injury risk. However, there has been little consideration of the relationship between lower limb screening and the loading response to soccer activities. Objective: To quantify the efficacy of using screening tests to predict the loading elicited in soccer-specific activities, and to develop a hierarchical ordering of musculoskeletal screening tests to identify test redundancy and inform practice. Design: Correlational. Setting: Professional soccer club academy. Participants: 21 elite male soccer players aged 15.7 ± 0.9 years. Intervention: Players completed a battery of five screening tests (knee to wall, hip internal rotation, adductor squeeze, single leg hop, anterior reach), and a 25min standardised soccer session with a GPS unit placed at C7 to collect multi-planar PlayerLoad data. Main Outcome Measures: Baseline data on each screening test, along with uni-axial PlayerLoad in the medio-lateral, anterio-posterior and vertical planes. Results: Stepwise hierarchical modelling of the screening tests revealed that dominant leg knee to wall distance was the most prevalent and powerful predictor of multi-planar PlayerLoad, accounting for up to 42% of variation in uni-axial loading. The adductor squeeze test was the least powerful predictor of PlayerLoad. Of note, one player who incurred a knee injury within three weeks of testing had shown a 20% reduction in knee to wall distance compared with peers, and elicited 23% greater PlayerLoad, supporting the hierarchical model. Conclusions: There was some evidence of redundancy in the screening battery, with implications for clinical choice. Hierarchical ordering and a concurrent case study highlight dominant leg knee to wall distance as the primary predictor of multi-axial loading in soccer. This has implications for the design and interpretation of screening data in elite youth soccer.