Exercise improves brain plasticity and learning capacity by increasing alertness through a neural circuit involving the adrenals, vagus nerve, and locus coeruleus.

“And while there are a host of mechanisms involving long-term changes in things like brain-derived neurotrophic factor, and increases in lactate, which might open the door to plasticity, and so on and so forth, it does seem that one of the major ways that exercise improves our brain function, and our ability to learn, is simply by increasing our levels of alertness.”