Dual-Task Single-Leg Hop Performance Exposes Persistent Asymmetry and Movement Deficits After Anterior Cruciate Ligament Reconstruction: A Randomised Crossover Experimental Study.

Background: Dual-task paradigms are increasingly used to investigate cognitive-motor interactions after anterior cruciate ligament reconstruction (ACLR), yet their effects on hop performance, movement quality and limb symmetry remain insufficiently quantified. The objective of this study was to compare these outcomes under single- and dual-task conditions between individuals after ACLR and healthy controls. Methods: Thirty-one participants (15 ACLR and 16 healthy controls) were included in this multicentre randomised repeated-measures experimental study. Participants performed the single-leg hop for distance (SLHD) under single-task and dual-task conditions using counterbalanced sequences. Movement quality was assessed using the Qualitative Assessment of Single-Leg Landing Scale (QASLS). In the dual-task condition, participants performed the hop while simultaneously completing a standardised visuo-attentional working-memory task. Dual-task cost (DTC) was calculated for SLHD, QASLS and limb symmetry index (LSI). The primary outcome was SLHD DTC. Analyses were based on linear mixed-effect models, with sequence-specific findings reported descriptively to support transparency regarding the counterbalanced design. Results: Under dual-task conditions, SLHD DTC was numerically higher in the ACLR group than in controls in sequences A1 (6.5 ± 6.5% vs 2.7 ± 6.9%; Conclusion: Dual-task conditions were associated with measurable changes in SLHD performance, movement quality and limb symmetry after ACLR.