The coordination of upper and lower limbs in curve-turning walking of healthy preschoolers: Viewed in continuous relative phase

Abstract

BackgroundCoordination is the ability to assemble and maintain appropriate relations between joints. Investigating limb coordination in curve-turning (CT) walking could provide insightful information about the coordinating strategies and neuro-musculoskeletal system (NMSS) control in human motion. Research questionAlthough preschoolers have already established an adult-like gait, how preschoolers perform their specific gait pattern when walking in CT and what coordination strategies they would choose during the turning process have not yet been systematically considered. Therefore, this study was aimed to investigate preschoolers' coordination mechanism during asymmetric motion, in order to understand the development of their NMSS control in locomotion. MethodsKinematics data in the lower and upper limbs of 45 healthy preschoolers walking with the curve-turning task was measured by the Coda Motion System. The Continuous Relative Phase (CRP) angle and the variability between the knee and ankle, hip and knee, as well as the thorax-humerus joint (THJ) and elbow were calculated. ResultsThe outcome demonstrates that as the curve angles increased, the stride length and Froude number of preschoolers significantly decreased (p < 0.05 for all); meanwhile, a more out of phase coordination pattern in CRP and an increase in VCRP values were found. Group analysis showed that the significant differences in CRP and VCRP between preschoolers and adults increased with curve angles in all coupled joints - the highest in that of the Knee-Ankle coupling, followed by those of the Hip-Knee and THJ-Elbow. SignificanceOur results suggest that to achieve curve-turning, preschoolers first chose to modify their STP, then to adjust coordination for coupling-joints in the Knee-Ankle, Hip-Knee, and THJ-Elbow systems. Additionally, preschoolers are still in a gait fine-tuning period and their NMSS control of motion is not as precise as that of adults.