Developmental Trends in Postural Adjustments During Reaching in Early Childhood

Reaching is a fundamental motor skill essential for daily living, with over 50% of daily activities involving reaching movements. Understanding the development of postural adjustments made during reaching in early childhood is crucial for motor development. This study investigated the developmental characteristics of postural adjustments made by children aged 3-6 years during reaching tasks. A total of 135 typically developing children from Chinese kindergartens participated in this study. Kinematic and electromyographic (EMG) data were collected using an infrared motion capture system and surface electromyography, respectively. A two-way ANCOVA was performed to examine the effects of age and gender on kinematic and electromyographic parameters. Post hoc analyses revealed that completion time and shoulder angle showed a linear decreasing trend (p < 0.05). The variable wrist joint had an increasing trend in the high-touch task, while the elbow joint showed a nonlinear decreasing trend (p < 0.05). EMG results regarding Extensor Carpi Ulnaris (ECU) showed a decreasing trend at all phases (p < 0.05). The developmental patterns observed suggest that children progressively utilize more distal (wrist) and fewer proximal (elbow and shoulder) joints during reaching, indicating the maturation of motor patterns. However, the mechanisms of anticipation and compensation for children aged 3-6 are not yet fully understood.