The test was conducted with only three test criteria... after learning the same topic, 1/3 of the group did not perform any exercise, another 1/3 did 35 minutes of exercise right afterwards, and the last 1/3 did exercise 4 hours later.
When tested two days later, it was the group that exercised 4 hours afterwards that did the best. The next best group was the one that did NO exercise, and the one that exercised right afterwards was last (but quite close to the 2nd place).
http://www.livescience.com/55095-exercise-helps-you-retain-new-info.html