Intra- and inter-subject variation in lower limb coordination during countermovement jumps in children and adults

The purpose of the present study was to investigate the coordination pattern and coordination variability (intra-subject and inter-subject) in children and adults during vertical countermovement jumps. Ten children (mean age: 11.5±1.8years) and ten adults (mean age: 26.1±4.9years) participated in the experiment. Lower body 3D-kinematics and kinetics from both legs were obtained during 9 vertical jumps of each subject. Coordination pattern and coordination variability of intra-limb and inter-limb coupling were established by modified vector coding and continuous relative phase. The adult group jumped higher and with less performance variability compared to the children. Group differences were mainly observed in the right-left foot coupling. The intra-subject coordination variability was higher in coupling of proximal segments in children compared to adults. No group differences were observed in inter-subject variability. Based on these results, it was concluded that the same movement solutions were available to both age groups, but the children were less able to consistently utilize the individually chosen coordination pattern. Thus, this ability appears to be developed through normal ontogenesis.