Resolution of post-concussive symptoms (PCS) is a marker of recovery. However, it is unclear whether subtle impairments re-emerge in the context of increased demands. This study examined the effect of strenuous exercise on clinical symptoms and cognitive efficiency in children and adolescents after PCS resolution following concussion. We recruited concussed children and adolescents (n=30) on presentation to an Emergency Department (ED), and compared them to community-sourced non-injured controls (n=30), matched for age, and cognitive function. At Day 2 post symptom resolution, concussed participants (and controls) completed an exercise protocol, and pre- and post exercise assessments of PCS and computer-based cognitive efficiency. Findings demonstrated that, compared to controls, participants with recent concussion showed an overall reduction in PCS post-exercise (p=0.048), less impact of exercise on PCS than controls (p=0.021), and faster reaction times on computer-based cognitive tasks, even where cognitive demands were high (ps<0.05). These results provide preliminary support for the use of moderate exercise for the reduction of concussion post-symptom, as suggested in recent clinical guidelines.

Recovery from concussion in childhood is poorly understood, despite its importance in decisions regarding return to normal activity. Resolution of post-concussive symptoms (PCS) is widely employed as a marker of recovery in clinical practice; however, it is unclear whether subtle impairments persist only to re-emerge in the context of increased physical or cognitive demands. This study aimed to examine the effect of strenuous exercise on clinical symptom report and neurocognition in children and adolescents after PCS resolution after concussion. We recruited children and adolescents with concussion (n = 30) on presentation to an Emergency Department (ED). At Day 2 and Day 10 post-self-reported symptom resolution, participants completed a strenuous exercise protocol, and pre- and post-exercise assessment of PCS and neurocognition. Results demonstrated an overall reduction in PCS from Day 2 to Day 10 post-symptom resolution, with no evidence of symptom increase after strenuous exercise at either time point. Neurocognitive performance was linked to task complexity: on less cognitively demanding tasks, processing speed was slower post-exercise and, unexpectedly, slower on Day 10 than Day 2, while for more demanding tasks (new learning), Day 2 exercise resulted in faster responses, but Day 10 processing speed post-exercise was slower. In summary, we found the expected recovery pattern for PCS, regardless of exercise, while for neurocognition, recovery was dependent on the degree of cognitive demand, and there was an unexpected reduction in performance from Day 2 to Day 10. Findings provide some suggestion that premature return to normal activities (e.g., school) may slow neurocognitive recovery.