Regular exercise improves our ability to think and remember through the creation of new brain cells, a process known as neurogenesis.
From this NY Times article, How Testosterone May Alter the Brain After Exercise:
“A new study found that male sex hormones surge in the brain after exercise and could be helping to remodel the mind”.
They tested to see if rats produce the testosterone in the brain by shutting off production in the testes (castration). Further, some of the animals also were injected with a drug that negated the effects of testosterone produced by the brain. Some rats were not altered. They were then divided into groups, sedentary and active rats. The active rats exercise on treadmills for two weeks; the sedentary rats played video games (not really).
Quote from the article:
“They found that, compared with the sedentary animals, the running rats had significantly more of a potent testosterone derivative called
dihydrotestosterone, or DHT, in their brains. Even the brains of rats that had been castrated sloshed with DHT.
So the exercise had prompted increased production of the hormone…
In essence, exercise prompts the production of more DHT. And more DHT helps to create more new brain cells”.
And one last quote:
"Do women gain less brain benefit from exercise than men?
“It’s unlikely,” Dr. McEwen says. One reason that early experiments into exercise and neurogenesis tended to be performed in female rats was that “in rats, females exercise more than the males,” he said. “They’ll run for hours and keep running, even when they’re old.” Elderly males, in contrast, willingly quit working out. In those experiments, neurogenesis was plentiful in the female brains.
“It’s very probable that estrogen plays a role” like that of DHT in the female brain after exercise, Dr. McEwen says”.
It is worth noting that the exercise was classified as mild-intense, jogging or walking. Also worth noting that it has been established that more intenseexercise produces more testosterone than less intense exercise. It could be that intense exercise is better for brain remodeling, but that was not what was tested.