Acute aerobic exercise modulates resting-state EEG microstate dynamics in individuals with internet addiction

Internet addiction (IA) is associated with impaired cognitive control and altered large-scale brain dynamics. Electroencephalogram (EEG) microstates provide a sensitive index of rapid neural network organization; however, whether acute aerobic exercise can modulate abnormal microstate dynamics in individuals with IA remains unclear. Forty young adults [IA: n = 20; healthy controls (HC): n = 20] completed resting-state EEG recordings before and after a single 30-min bout of moderate-intensity aerobic cycling. Microstate duration, occurrence, contribution, and transition probabilities were analyzed using mixed-design repeated-measures with time (pre/post) and Microstate (A-D) as within-subject factors and group (IA/HC) as a between-subject factor. Spearman correlations examined associations between exercise-induced microstate changes and IA severity. For microstate duration, the IA group exhibited longer duration of Microstate A than HC group at baseline (t = 2.47, p = 0.018). IA group showed reduced Microstate D occurrence at baseline compared with HC (t = 4.23, p < 0.001), followed by a significant post-exercise increase (t = -4.23, p = 0.001), eliminating group differences. Microstate contribution showed a significant Time × Group interaction [F _{(1, 38) =} 4.68, p = 0.037, η² = 0.110], with Microstate D contribution increasing selectively in the IA group (t = -3.71, p = 0.001). Changes in Microstate D occurrence were negatively correlated with IA severity (ρ = -0.55, p = 0.012). A single session of aerobic exercise rapidly normalizes aberrant microstate dynamics in IA, particularly within Microstate D, highlighting exercise as an effective acute neuromodulatory intervention.