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Exercise helps learning by raising alertness
Jogging, brisk walking, moderate to high intensity resistance training, sprint intervals on a fan bike, and even tai chi or a yoga class all raise autonomic arousal and alertness. They raise circulating dopamine, epinephrine, and norepinephrine, and they raise factors like BDNF and IGF-1. A list of fifty chemicals that exercise increases and that facilitate plasticity could be made, yet the biggest effect is the pro-arousal one.
That alertness allows better focus over the following one to six hours, and what happens in those hours decides whether anything is learned. Being alert without being focused on anything specific won't help memory specifically, though it may help brain health. Someone who is alert and focused on learning without exercising first gets the same plasticity, since exercise offers nothing special for learning other than this arousal effect.
How does exercise raise BDNF in the brain?
Carl Cotman's lab at the University of California, Irvine, reported in a 1995 paper in Nature that rats running on wheels had more BDNF in the hippocampus. BDNF is a protein that supports the growth of synapses and the strengthening that underlies long-term memory. Later work showed that muscle and liver contribute signaling molecules that also affect BDNF production.
Why does arousal affect performance?
Robert Yerkes and John Dodson reported in 1908 that mice learned a task best at a moderate level of electric shock, while very weak or very strong shocks slowed learning. The relationship between arousal and performance has since been drawn as an upside-down U. The pattern is called the Yerkes-Dodson law, and it holds more strongly for simple tasks than for complex ones.
Why does norepinephrine sharpen attention?
The locus coeruleus, a small brainstem structure, supplies most of the brain's norepinephrine. Its neurons project across the cortex and fire more during alert, focused states. Gary Aston-Jones and Jonathan Cohen proposed in a 2005 paper in Annual Review of Neuroscience that norepinephrine raises the gain of cortical neurons, so signals stand out more sharply from background activity.
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