A recent systematic review and meta-analysis by Lal et al. examined the effect of exercise on concussion symptoms. The authors found "clear benefits of physical exercise in decreasing the Post-Concussion Symptom Scale (PCSS) score, [the] percentage of patients with symptoms of a concussion, and [the] duration of symptoms" among other benefits.
How? They suggest that not only does (appropriate) exercise improve cerebral blood flow and oxygenation, but it may also reduce anxiety and depression by improving mood and behaviour.
Read the article here!