Development of motor control based on EMG-EMG coherence in preschool children

Abstract

Problem Statement: It has been observed recently that reduced opportunities for physical activity have led to an increasing number of children struggling with motor control and body coordination. Physical movements occur through nerve signals transmitted from the brain to the muscles. In recent years, the coherence method has been adopted to assess motor control function by measuring the synchronization of rhythmic activity between the brain and muscles or between muscles. This study aimed to examine the relationship between electromyogram coherence in two muscles during walking and factors, such as age, body size, and exercise frequency in daily life, to clarify the characteristics of functional development of motor control. Approachs: The study involved 26 healthy young children. Their height and weight were measured to calculate the body mass index (BMI), and muscle activity was recorded as they walked around a 26-meter rectangular path. Electromyography electrode sensors were placed at two sites on the dominant leg: the medial gastrocnemius (MG) and lateral gastrocnemius (LG). A frequency analysis was conducted on the recorded electrical signals to calculate the coherence between MG and LG during the stance phase. Statistical analysis was performed to calculate correlation coefficients between EMG-EMG coherence and factors, such as age in months, height, weight, and BMI. Additionally, a parental questionnaire was administered to assess the frequency of their children's physical activity. Parents reported the number of days per week in which their children engaged in at least 60 minutes of physical activity. Based on these responses, the participants were categorized into three groups for comparison: low frequency (0– 2 days/week), medium frequency (3–4 days/week), and high frequency (5–7 days/week). Results: No significant correlation was observed between EMG-EMG coherence and age or body size. In contrast, the high-frequency group demonstrated significantly higher EMG-EMG coherence compared to the low-frequency group. Although no significant differences were found, EMG-EMG coherence was higher in the medium-frequency group compared to that in the low-frequency group, and higher in the high-frequency group compared to that in the medium-frequency group, suggesting a trend of increased EMG-EMG coherence with higher movement frequency. Conclusions: The results indicated that EMG-EMG coherence was higher in the high-frequency exercise group than in the low-frequency exercise group, suggesting a link between daily exercise and development of motor control function. From a functional standpoint, this highlights the importance of providing exercise opportunities from early childhood.