Via NY Times, by Gretchen Reynolds

To learn more about how exercise affects the brain, scientists in Ireland recently asked a group of sedentary male college students to take part in a memory test followed by strenuous exercise.

First, the young men watched a rapid-fire lineup of photos with the faces and names of strangers. After a break, they tried to recall the names they had just seen as the photos again zipped across a computer screen.

Afterward, half of the students rode a stationary bicycle, at an increasingly strenuous pace, until they were exhausted. The others sat quietly for 30 minutes. Then both groups took the brain-teaser test again.

Notably, the exercised volunteers performed significantly better on the memory test than they had on their first try, while the volunteers who had rested did not improve.

Meanwhile, blood samples taken throughout the experiment offered a biological explanation for the boost in memory among the exercisers. Immediately after the strenuous activity, the cyclists had significantly higher levels of a protein known as brain-derived neurotrophic factor, or BDNF, which is known to promote the health of nerve cells. The men who had sat quietly showed no comparable change in BDNF levels.

For some time, scientists have believed that BDNF helps explain why mental functioning appears to improve with exercise. However, they haven’t fully understood which parts of the brain are affected or how those effects influence thinking. The Irish study suggests that the increases in BDNF prompted by exercise may play a particular role in improving memory and recall.

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