Findings of a recent study out of Dartmouth College support the claim that regular, aerobic exercise makes some humans smarter. The recent popular-press article, which alerted me to this fact, states that
in about 60 percent of the population, [exercise] may be responsible for the expression of a gene that floods your cells with “brain derived neurotrophic factor" — or BDNF — a protein that is thought to help with mental acuity, learning and memory.
In terms of their memory of novel objects, subjects who performed moderate aerobic exercise for four weeks, including exercise on the day of the test, performed better than subjects in the other three test groups: 1) those that exercised for four weeks but not on the day of the test, 2) those that exercised only on test day, and 3) those that did not exercise the four weeks prior to the test.
According to the lead researcher, the key is regularity rather than intensity and also exercising more than half of the days of the week.
I'm operating under the assumption that until it’s proven that I don’t have the exercise-makes-me-smarter gene, I’ve got one more “reason” for cycling regularly.