The influence of physical activity, sedentary time, and adiposity, on behavioral and neuroelectric measures of attentional inhibition

Physical inactivity and excess adiposity are thought to be detrimental not only to physical but cognitive health as well. However, the cognitive implications of these interrelated health factors are rarely examined together, therefore, little is known regarding the concomitant contribution of physical activity and adiposity to cognition. Furthermore, time spent being sedentary, known to be distinct from low physical activity, is a public health concern given its propensity to exacerbate the health implications of inactivity on both physical and mental health. However, the association between sedentary time and cognition remains unknown. The research presented herein sought to examine the relationship between objectively measured physical activity, adiposity, sedentary time, and behavioral and neuroelectric indices of cognitive control among 25-45 year olds. Percent of time spent engaging in moderate-to-vigorous physical activity (MVPA) and sedentary behaviors (%Sedentary) was monitored using an accelerometer worn for at least 4 days (minimum 8 hours/day). Whole body adiposity (%Fat) was assessed using Dual Energy X-ray Absorptiometry (DXA). Attentional inhibition, a component of cognitive control, was assessed using a modified Eriksen Flanker task. Neuroelectric function was assessed using event-related brain potentials. Specifically, the changes (incongruent - congruent task conditions) in amplitude of the P3 waveform in a central-parietal region of interest (ROI) was used to index the ability for modulation of attentional inhibition. After adjusting for significant covariates (age, sex, and intelligence quotient), %MVPA was a positive predictor of accuracy in the incongruent condition of the Flanker task (β = 0.31, P = 0.03), signifying that individuals who engaged in greater physical activity exhibited superior attentional inhibition. Additionally, results showed an interaction effect of %Fat and %MVPA attentional inhibition (β = 0.45, P = 0.04), suggesting that individuals with lower chronic activity and greater adiposity exhibited poorer attentional inhibition. The positive influence for physical activity on cognitive control persists even following the adjustment of demographical variables, intellectual ability, and adiposity. Neuroelectrically, %Sedentary time was inversely related to the difference in the ROI mean amplitude, whereby participants who spent more time being sedentary exhibited poorer ability to flexibly modulate attentional resources in response to greater task demands. Given that most adults spend much of their day engaging in sedentary behaviors, these findings provide support for public health initiatives to decrease sedentary behaviors and increase MVPA in order to prevent decrements in both physical and cognitive health