Physical Fitness, Visuospatial Working Memory, and Task-Related Hemodynamic Responses in Preschool Children: A Cross-Sectional fNIRS Study

This cross-sectional study examined the association between physical fitness and visuospatial working memory (VSWM) in preschool children and explored the statistical role of task-related cortical activation in this association. Ninety preschool children aged 4–6 years completed a standardized physical fitness assessment and a VSWM task while cortical hemodynamic responses were recorded using functional near-infrared spectroscopy (fNIRS). Physical fitness was positively associated with VSWM performance (r = 0.587, p < 0.001), and this association remained significant after adjustment for age, sex, and body mass index (standardized β = 0.594, p < 0.001). After Benjamini–Hochberg false discovery rate correction across 20 regions of interest, physical fitness was significantly associated with task-related activation in the visual association cortex (VAC), right dorsolateral prefrontal cortex (R-DLPFC), and right orbitofrontal cortex (R-OFC), whereas VSWM performance was significantly associated with activation in the VAC, R-DLPFC, and right frontopolar cortex (R-FPC). The VAC showed a particularly strong negative association with VSWM performance (r = −0.903, p < 0.001), which remained robust across additional sensitivity analyses. In a covariate-adjusted indirect-effect analysis, physical fitness showed a significant indirect association with VSWM performance through VAC activation (indirect effect = 0.0090, 95% bootstrap CI [0.0056, 0.0125]). These findings indicate that better physical fitness is associated with better VSWM performance in preschool children and that VAC activation showed a significant statistical indirect association with the fitness–VSWM relationship. This activation pattern is consistent with, but does not establish, the neural efficiency hypothesis. Longitudinal and experimental studies are needed to determine the temporal direction and potential causal mechanisms underlying these associations.