…[P]hysical, aerobic exercise performed right after a memory has been formed intensifies the imprinting, Dr. Roig says. It makes the memory stronger.
In the short term, though, exercise may leave the brain overstimulated, he continues, making it less able to pinpoint and access new memories. That may be why men who had exercised after learning the new skill performed worst during the first motor-memory recall test.
But they performed better in the long term, because their memory of the new skill was, it would seem, sturdier.