Detection of season-long post-concussion motor deficits in female soccer players using a 3D goal equivalent manifold framework

This study examined whether a geometry-based movement variability framework (3D Goal Equivalent Manifold, GEM) could detect persistent motor control deficits across a competitive season in female soccer players with a history of concussion, and compared its performance with the traditional 2D GEM approach. Twenty-five female varsity soccer players (11 with concussion history within 3 years, 14 without) completed bilateral bodyweight squats synchronized with a metronome (40 beats per minute) at pre-, mid-, and post-season. Whole-body kinematics were captured using a markerless motion capture system. 3D GEM analysis decomposed variability into task-relevant and task-irrelevant components, producing a 3D performance index (PI) and temporal persistence metrics (λ). Players with concussion history exhibited significantly lower 3D PI scores (M = 9.48 ± 1.60) compared to those without (M = 16.26 ± 2.45; p = 0.017), with no significant seasonal changes or interactions. No significant differences emerged for temporal persistence metrics, although the concussion group consistently showed trends toward less effective regulation in task-relevant dimensions. The 3D GEM approach effectively identified persistent motor control deficits in female soccer players with concussion histories, underscoring its potential for clinical assessments and monitoring throughout rehabilitation and return-to-play programs.