Physical exercise is equally important as cognitive exercise in maintaining a healthy brain, according to new research.

The study found exercise increases the number of stem cells that are actively generating new nerve cells in the brain. This would prohibit the decline normally observed as animals age.

Researchers found that the Growth Hormone (GH), originally discovered as a potent stimulator of animal growth, was increased in the brain of running animals. This stimulates the activation of new neural stem cells.

Researchers are now seeking to determine whether this GH–dependent increase in stem cell activity is able to reverse the cognitive decline seen in old animals by increasing production of new nerve cells.