A New York times article asks Do the Brain Benefits of Exercise Last? In a word, no. It appears that desirable changes are not permanent, much like when a person stops exercising the body reverts to its former de-conditioned state.
Experimenters took two groups of rats, one group exercised on a treadmill and the other did not exercise. Afterward, the researchers
compared the animals’ performance on the memory test, as well as the number of new brain cells in the hippocampus of each group of rats.
They found that:
”The rats that had run were much faster on the water maze test than the control animals. They also had at least twice as many newborn neurons in the hippocampus.
But those advantages faded after several more weeks of not running. The brains of the animals that had been inactive for three weeks contained far fewer newborn neurons than the brains of the animals that had rested for only one week. The brains of the animals that had been inactive for six weeks had fewer still”.