Static and Dynamic Functional Network Alterations Associated with Endurance Training.

Long-term endurance training is associated with widespread changes in brain organization, but how these changes extend to large-scale networks across different temporal scales remains unclear. We combined static functional connectivity analysis with dynamic multilayer network modeling to examine resting-state fMRI data from 25 endurance athletes and 31 matched controls. At the static level, athletes exhibited significantly enhanced within-network functional connectivity in the sensorimotor, salience, cingulo-opercular, and auditory networks, together with reduced system segregation of the frontoparietal network. At the dynamic level, none of the between-group differences in flexibility, promiscuity, cohesion, or disjointedness survived correction for multiple comparisons. In exploratory analyses at uncorrected thresholds, several between-group patterns emerged, including reduced flexibility in the subcortical network, increased promiscuity in the sensorimotor network, and reduced disjointedness in the visual and auditory networks. Several static network measures and selected dynamic measures were also associated with cumulative training exposure across individuals. Overall, the statistically supported findings indicate that endurance training is primarily associated with strengthened baseline functional integration within motor, interoceptive, and cognitive-control systems. The exploratory dynamic analyses further suggest potential differences in the temporal organization of large-scale functional networks, providing hypotheses for future investigation.