Association of Physical Activity, Perceived Physical Fitness, and Cognitive Performance in School‐Aged Children: A Cross‐Sectional Study From the <scp>Break4Brain</scp> Project

ABSTRACT Physical activity (PA) has been associated with cognitive performance in children, although the underlying mechanisms remain unclear. Objective: This study examined whether perceived physical fitness mediates the association between PA and cognitive outcomes, while exploring sex differences. Sex‐stratified multigroup structural equation modeling was conducted using cross‐sectional baseline data from the Break4Brain project ( n = 722 [354 girls], aged 10–12). PA was not associated with cognitive flexibility in either sex. In girls, PA was negatively associated with selective attention ( β = −0.22, p = 0.002), whereas no significant associations with cognitive outcomes were observed in boys. PA was positively associated with perceived physical fitness in boys ( β = 0.51, p &lt; 0.001) and girls ( β = 0.56, p &lt; 0.001). In girls, perceived physical fitness was positively associated with selective attention ( β = 0.35, p &lt; 0.001) and significantly mediated the relationship between PA and selective attention ( β = 0.17, 95% CI [0.08, 0.26]). These findings suggest sex‐specific pathways linking PA, perceived physical fitness, and cognitive performance.