Objective: To explore potential effects of aerobic exercise on cognitive function, fatigue, and neuroplasticity after stroke or traumatic brain injury.

Design: A randomized controlled pilot study.

Subjects/patients: Twelve participants, 10 men and 2 women aged 16-65 years diagnosed with acquired brain injury (moderate to severe stroke or traumatic brain injury), enrolled in an outpatient rehabilitation programme at least 3 months post-injury.

Methods: The intervention group (n = 6) participated in 30 min of aerobic exercise 3-4 times/week for 8 weeks during their outpatient rehabilitation. The control group (n = 6) received routine physical therapy. In addition, both groups received rehabilitation according to their rehabilitation plan. Neuropsychological and endurance testing was performed before and after the intervention and at a 3-month follow-up. Functional magnetic resonance imaging was performed before and after the intervention.

Results: Preliminary findings show no significant difference between the groups regarding cognitive variables, fatigue, or neuroplasticity. However, working memory/executive demanding processing speed, measured with the Paced Auditory Serial Addition Test, improved significantly (p = 0.042) in the aerobic exercise group and there were trends of improvements on several other executive tests in the aerobic exercise group. Automatic visual search speed improved in the control group (p = 0.027).

Conclusion: The question of whether aerobic exercise promotes cognition and fatigue after brain injury remains unanswered. This randomized controlled pilot study and its preliminary findings indicate greater improvements in executive processing speed in the aerobic exercise group, while more automatized attention speed improved more in the control group. The experiences from this study might facilitate the design of future studies on this intriguing topic.

Trial registration: ClinicalTrials.gov Identifier: NCT07429526.