Topological data analysis of postural sway: characterizing balance control during childhood development

BACKGROUND: Postural control matures through gradual refinement of sway organization, yet traditional CoP measures capture only variability and not the underlying geometric structure. Topological Data Analysis (TDA) offers a complementary approach by quantifying the persistence and complexity of sway dynamics. This study applied TDA to investigate developmental and task-related differences in CoP topology from childhood to adulthood. METHODS: A total of 460 healthy participants (ages 7-12 years and young adults) completed eight standing balance tasks that manipulated visual input, base of support (BoS), and cognitive load. For each 30-s CoP trial, Vietoris-Rips persistence diagrams were computed, and four H1-based TDA metrics were extracted: H1_Wasserstein distance, H1_TotalPersistence, Persistent Entropy, and H1_NumLongLoops. Mixed-design ANOVAs evaluated the effects of Age, Gender, Vision, BoS, and Cognitive Dual-Tasking (CDT) on each metric. RESULTS: All TDA metrics exhibited strong age effects (all p < 0.001), with children showing greater persistence magnitudes and more long-lived loops than adults, reflecting less stable and more oscillatory sway organization. Vision significantly modulated H1_Wasserstein and Total Persistence (p < 0.001), with eye closure producing pronounced increases. Single-leg stance robustly amplified all TDA measures (p < 0.001). CDT induced moderate but significant alterations in several metrics, whereas Persistent Entropy remained insensitive to visual deprivation (p = 0.168). Gender differences were generally small but interacted with task difficulty for selected outcomes. CONCLUSION: TDA revealed systematic developmental transitions in the topology of CoP dynamics, shifting from rich multi-loop structures in childhood to topologically simpler and more stable configurations in adulthood. These findings support TDA as a sensitive and physiologically meaningful approach for evaluating balance maturation and may aid in detecting atypical postural control patterns in clinical or developmental contexts.