The Response of the Default Mode Network to Aerobic Exercise in Pediatric Concussion

Submaximal aerobic exercise is an evidence-informed strategy for concussion management. However, its impact on the concussed pediatric brain remains poorly understood. A seminal adult study reported stability of default mode network (DMN) functional connectivity before and immediately after aerobic exercise in adults with mild traumatic brain injury. Comparable data do not exist in children, despite known developmental neurophysiological differences between children and adults. This study examined DMN network stability before and after submaximal aerobic exercise in pediatric sport-related concussion. In a controlled cohort design, 18 concussed participants (within 4 weeks of injury; 15.2 ± 1.8 years; 33% female) and 18 age- and sex-matched controls (14.5 ± 2.1 years; 50% female) completed resting-state functional magnetic resonance imaging scans pre- and post-exercise. Exercise intensity was set to 85% of the individualized symptom-limited heart rate achieved on a Buffalo Concussion Treadmill Test performed 24-48 h prior. Functional connectivity was assessed across four DMN regions of interest (posterior cingulate cortex, medial prefrontal cortex, left lateral parietal cortex, right lateral parietal cortex). Graph theory analyses conceptualized each region as a network node. Region of interest-based analyses demonstrated reduced pre- to post-exercise correlations across DMN pairs in both groups. Mean percent change was -25.8% (±12.7%) in concussion and -15.0% (±7.2%) in controls. However, no statistically significant within- or between-group correlational differences were observed, consistent with adult findings. In contrast, graph theory revealed significant post-exercise reductions in network efficiency (β = -0.17, p = 0.015), cost (β = -0.18, p = 0.014), and degree centrality (β = -0.53, p = 0.001) exclusively in the concussion group, driven primarily by the right lateral parietal cortex. While correlational analyses suggest DMN stability similar to adults, graph metrics indicate reduced network connectedness following exercise in pediatric concussion. These findings underscore the need to move beyond symptom-based frameworks and examine exercise-related neurophysiological responses in youth concussion.