Postural control development from late childhood through young adulthood

Background: The development of stable postural control is characterized by changes in sway variability and periods of rapid reorganization of motor system components. Research question: The current study examined whether changing biomechanical and perceptual demands influences the postural control behavior during development. Method: The center of pressure (COP) was assessed via a cross-sectional design. Data were collected from 48 females in three age groups (late childhood, mid-adolescence, and young adulthood) during four quiet stance conditions: (1) eyes open with feet apart, (2) eyes open with feet together, (3) eyes closed with feet apart, and (4) eyes closed with feet together. Linear measures included total path length of the COP and the mean/standard deviation of the overall COP position and speed. To characterize the sway patterns via nonlinear analyses, the speed and two-dimensional positional time series were submitted to sample entropy and Renyi entropy, respectively. Results: The linear results indicated that the late childhood group displayed longer COP trajectories (p < .001) and faster and more variable COP speed (p?s < .001). These results held for both the feet apart and feet together conditions, independent of vision. The nonlinear results indicated that the late childhood group exhibited less regularity, overall, in their COP sway position (i.e., Renyi entropy) compared to the two older groups in the feet apart condition (p?s ? .041), and to the young adults in the feet together condition, independent of vision (p < .001). However, the mid-adolescent group demonstrated greater regularity in their COP speed (i.e., sample entropy) when their eyes were closed compared to the other two groups, independent of stance (p?s < .05). Significance: The linear results support previous findings, while the nonlinear measures indicate sway characteristics that may provide a window into the development of underlying control processes that regulate quiet standing.