From stiffness to automaticity: visuomotor training alters postural control strategies in older adults.

Abstract

Aging is often associated with a maladaptive "stiffness" strategy of postural control, which limits adaptability and increases fall risk. Complex visuomotor training (e.g., juggling) may counteract this decline, but the relationship between biomechanical reorganization and cognitive cost reduction remains unclear. We hypothesized that juggling would induce a shift from stiffness to "active monitoring" and reduce the dual-task cost. This exploratory secondary analysis of a randomized crossover trial consists of twenty-five older adults (70 ± 4 years). Participants underwent 4 weeks of juggling training versus a passive control period. Postural sway was assessed using a force platform to analyze kinematic metrics reflecting sway activity (path density) and spatial precision (radial standard deviation). Cognitive cost was assessed via dual-task cost during a counting task. Linear mixed models were used for analysis. Juggling training significantly increased path density (p = 0.014) and improved central precision (reduced radial standard deviation, p = 0.040). This pattern indicates a transition to an "active monitoring" strategy, effectively "unfreezing" rigid postural control. However, this biomechanical reorganization was not accompanied by a statistically significant reduction in dual-task cost (p = 0.08). Visuomotor training effectively "unfreezes" rigid postural strategies in older adults, promoting active, exploratory control. However, these findings should be interpreted as hypothesis-generating. The lack of significant cognitive cost reduction suggests a temporal dissociation: biomechanical flexibility is restored before full automatization occurs, warranting verification in larger, longitudinal studies. The study was retrospectively registered (30.10.2023) at ClinicalTrials.gov (NCT06108713).