The role of vision in obese and normal-weight children's gait control

INTRODUCTION: Research has found lower motor competence and alternative movement patterns in obese children when compared to normal-weight peers, thereby linking childhood obesity to non-optimal motor development. Some authors suggested that perceptual-motor difficulties may account for obese children’s poorer motor behavior; however, specific evidence is currently lacking. Therefore, the purpose of this study was to examine the effect of altered visual information on the control of spatiotemporal and kinematic gait parameters in obese versus normal-weight children. METHODS: Sixteen obese and sixteen normal-weight children, matched according to gender (4 ♂, 12 ♀) and age (11.2 ± 1.5 years), participated in this study. Internationally accepted cut-off points for BMI in children were used for classification. Participants were asked to walk barefoot on a level instrumented walkway at a constant self-selected speed during LIGHT and DARK conditions. Using Qualisys Track Manager and Visual 3D software, three-dimensional motion analysis was performed to calculate spatiotemporal parameters as well as sagittal trunk segment and lower extremity joint angles at heel-strike and toe-off. RESULTS: Self-selected speed, cadence and stride length were not significantly different between obese and normal-weight participants. Even when normalized for height, between group differences did not reach statistical significance. In the DARK condition, all participants walked at a significantly slower speed, decreased stride length and increased stride width. Without normal vision, obese children had a more pronounced increase in relative double support time than those within the normal-weight group, resulting in a significantly greater percentage of the gait cycle spent in stance. Walking in the DARK, both groups showed greater forward tilt of the trunk and restricted hip movement. In addition, all participants displayed increased knee flexion at heel-strike as well as decreased knee extension and ankle plantarflexion at toe-off compared to the LIGHT condition. CONCLUSIONS: The present study confirms the important contribution of vision to children’s gait control. The observed changes in spatiotemporal and kinematic parameters reflect their greater emphasis on maintaining dynamic balance rather than forward propulsion when walking in the DARK. However, the removal of normal vision affected the gait pattern of obese children to a larger extent than that of normal-weight peers. The different response in temporal phasing of obese participants during the DARK condition suggests an increased dependency on vision to control their gait. Next to the mechanical problem of moving excess mass, a different coupling between perception and action appears to be governing obese children’s motor coordination and control. Further research examining the potentially decreased perceptual-motor function of obese children is warranted, since it might impede performance of everyday life activities as well as the willingness to participate in physical activities