Visual guidance of walking in obese children

INTRODUCTION. It is well documented that childhood obesity has a negative impact on the motor competence. The presence of excess mass and a non-optimal distribution of that mass over the body hampers a smooth execution of motor task, especially in tasks that imply a displacement of (parts of) the body, like running or jumping. An alternative, but not exclusive, explanation for the lower motor competence in obese children is a lower quality of perceptual-motor functioning. This study investigates the integrity of perceptual-motor functioning by manipulating visual information during walking. METHODS. Sixteen obese children (OB; BMI: 29.92 +/- 4.90 kg/m²) between 7 and 12 years and sixteen normal weight control children (NW; BMI: 17.46 +/- 1.85 kg/m²) walked barefoot on an instrumented walkway at a constant self-selected speed. In the LIGHT condition, the room was normally lit, while in the DARK condition the room was completely darkened with the exception of a small light source at the end of the walkway. 3-D kinematics were collected through 8 infrared Proreflex cameras at 240 Hz. Data were averaged over the gait cycles of five trials in each experimental condition. Analyses of variance (2 (BMI group) x 2 (visual condition)) with repeated measures on the last factor were performed on each dependent variable. Significance level was set at p < .05. RESULTS. The walking pattern of obese children was characterized by a larger step width (p < .001), but no significant difference in walking speed, or any other spatiotemporal parameter, although they tended to walk slower as compared to their normal-weight peers. The visual manipulation resulted in a more conservative gait pattern, featured by a lower speed, cadence, and step length, but a larger step width in the DARK condition (all p-values < .001). Significant interaction effects on about half of the spatiotemporal parameters showed that the obese group was much more vulnerable to the absence of visual information, resulting in more time spent in stance phases in the DARK, while these differences were less pronounced in the normal-weight group. CONCLUSION. In sum, the adaptations to the gait pattern in the absence of light are indicative of a safer walking pattern in both the obese and the normal-weight children. The greater impact of altered visual conditions on obese children’s walking suggest that they might differently cope with sensory information during walking. This supports the hypothesis that differences in behavior between obese and normal-weight children might not solely be a problem of mechanics, but also a perceptual-motor problem