The present study analysed the association between time spent in SB in different contexts and EF in preschoolers. Although prior studies have assessed the relation between SB and EF in preschoolers [36, 37], the current study adds important findings to the existing literature, considering distinctive contexts where preschoolers are sedentary.
The study´s primary results showed that time spent in SB on weekend days was positively related to children´s IE, a measure to consider the trade-offs between speed-accuracy [30]. Indeed, a lower IE is associated to a more efficient task performance [30], what might indicate a harmful for children´s IE. Thus, the excessive time spent being sedentary during weekend seems to be detrimental to preschoolers' EF [14]. According to Lillard and colleagues [38], the information processing follows an inverted U shape, in such a way that the excess of information, as well as the content children are exposed, may lead to children's EF impairments [39]. Moreover, the assessed children spend twice as much time on SB during weekends than on weekdays. Excessive SB at this stage of life is associated with decreased white matter integrity in brain regions that support EF, such as the frontal and the prefrontal Thalamus [12].
It is important to highlight that the relationship between SB and EF in preschoolers is controversial [14, 40], partly due to the type of SB performed, and to the time spent being sedentary. The technology advances, and the easier access to electronic devices may predispose early age children to a greater amount of time exposed to screens [41], though specific educational TV, tablet, and computer programs developed for this public may positively contribute to children's learning process [42].
Although it is expected that sedentary time inside preschools could positively predict children´s EF, the current study showed no significant association with any of the assessed EF outcomes. Preschool´s context characteristics, such as inadequate material, lack of space, and teachers qualification to work with these specific age group, may influence the quality of the offered classes, and consequently, children´s cognitive learning [43]. The assessed children spend 10 hours per day at public preschools, located in low-income areas of a middle-income country, where social aspects that directly interfere with child´s development cannot be ignored. In addition, in several cases, parents are involved in an extensive work routine, that may contribute to a lack of quality interactions with their children, especially during week days, and consequently, on children's cognitive development [44].
The main strength of the current study is the analysis of sedentary time in different contexts and its repercussion in preschoolers’ EF. As far as we know, this is the first study to report such associations in young children, considering the context where SB happens, what may provide a new insight in the research field. Besides, the studied sample covers a critical geographical gap in this research area. However, our findings should be considered with certain parsimony, as the lack of information regarding the type/quality of SB performed in each context may be determinant to the reported associations. Finally, other factors involved with preschoolers´ EF (e.g., home and school environments, diet, motor skills, self-esteem, brain-derived factors, and others) [45] could be detrimental for the fit indexes, and should be further explored. Therefore, these outcomes emphasize a context-dependent influence of SB time on preschoolers’ EF, and demonstrate the relevance and priority of further studies to better discern types of SB.