Analysis of anticipatory postural adjustment characteristics in preschool children with different motor development...

This study aimed to analyze the characteristics of anticipatory postural adjustments (APAs) in 4-6-year-old preschool children under different visual conditions and to explore the association between motor development levels and APA-related measures.

Twenty-five children from a kindergarten in Shandong Province were recruited to perform a rapid arm-raising task under both eyes-open and eyes-closed conditions. Electromyography (EMG) signals from the trunk and lower limbs, as well as center of pressure (CoP) data, were synchronously recorded.

Analysis of the EMG onset timing of the external oblique and biceps femoris muscles and CoP-based postural stability indicators revealed that under the eyes-closed condition, children's CoP sway velocity increased significantly, with the equivalent area and radius showing an increasing trend. This indicates reduced postural stability and a high reliance on visual input. Analysis of muscle activation timing showed a tendency for earlier activation in the lower limb (biceps femoris) compared to trunk muscles, possibly reflecting a certain degree of proactive adjustment during postural preparation. Based on fine motor, gross motor, and balance control scores, K-means clustering categorized participants into two motor development types. Comparative analysis revealed trend-level differences in some EMG and CoP measures between clusters, suggesting that differences in motor development characteristics may be associated with different postural adjustment strategies.

This study provides preliminary evidence for understanding the developmental characteristics and individual differences of APAs in preschool children, and offers a reference for incorporating APA assessments into early motor ability screening and intervention programs.