Coordination strategies of lower limb muscles during curve-turning tasks in preschool children

Preschoolers are within their critical time in motion development; while muscles are the fundamental units in motion control and by monitoring activated intensity and duration of muscles, preschooler's motor ability which would disclose their potential pathogenesis quality can be objectively and quantitatively assessed. Although a large number of studies were available on this issue, questions still being there: what are the patterns and characteristics of lower limb muscles when they are facing with the curve walking(CW) tasks; and then how individual muscle or muscle groups coordinated while turning curves. Our purpose of this study is first to portray the patterns and characteristics of lower limb muscles of healthy preschoolers while CW and then to insight their muscles' coordination mechanism and "neuro-musculo-skeletal" feedback during motion.

35 healthy preschoolers and 35 healthy adults' lower limbs surface electromyography (sEMG) were collected while left and right CW and four muscle groups (Tibialis Anterior, Lateral Gastrocnemius, Rectus Femoris, and Biceps Femoris) were recorded. sEMG variables such as Muscle Activation Time, Total Duration of Activity Time, Average Muscle Activation Rate and Average Rate of Change were calculated. Paired sample t-test was used to explore the differences of sEMG variables between preschoolers and adults when turning curves.

Preschoolers would adjust the gait by changing the activation time and activation rate to fulfill the curve turning tasks; but they also showed variations in coordination mechanism when contrasting with the adults group. Those findings in preschoolers would support to build muscles' coordination mechanism and further insight to neuro-muscular skeletal feedback regulation.

Although preschoolers performed good enough to switching gait from normal walking to CW, but gaps in their abilities were still apparent when compared to adults. Hence, with the help of highly recognizable muscle coordination mechanism in CW, motor dysfunction in lower limbs of preschool children can be effectively identified.