**4.2 Active concussion recovery & rehabilitation**

Recent research suggests that rest until all symptoms resolve may not be best and that taking a more active approach to recovery for patients with persistent, chronic symptoms may improve recovery outcomes.

Given our understanding of concussion pathophysiology and changes in cerebral blood flow autoregulation as a result of the injury, it is believed that exercise intolerance may be a physiological biomarker of ongoing impairment [52]. Therefore the return of normal exercise tolerance can be then used to establish a sign for physiological recovery from concussion. Using any symptom-exacerbation as an individual's stopping criteria, individualized sub-symptom threshold aerobic exercise treatment programs has been shown to improve recovery time and aerobic ability in athletes with persistent concussion symptoms. This symptom improvement was also associated with improved fitness and autonomic function such as heart rate and blood pressure control and resulted in speeded recovery compared to non-active recovery study participants [53].

Active treatment targeted at system specific deficits that the patient is experiences has been shown to improve recovery. Specifically, ocular motor dysfunction is very common following sports-related concussion with a reported 90% of traumatic brain injury patients reporting vision or visual related symptoms [54]. Symptoms typically include: double vision, blurred vision, headache, dizziness, difficulty with reading or other vision-based tasks. The physical and cognitive control of eye movements requires a majority of the brain's pathways including fronto-parietal, temporal and occipital circuits as well as numerous subcortical

nuclei all of which are particularly susceptible to head injury [37]. Several studies have demonstrated the effectivity of ocular based rehabilitation for vision-based deficiencies in the general population and a growing number of investigations are showing similar results in the mTBI population with improvement in vision-related symptoms, reading ability and visual attention [55–58].
