The fact that exercise increases our fitness levels by making the muscles more resistant to fatigue is pretty well-known.
Past research has found exercise spurs the birth of new mitochondria - structures in the cells that produce the body's energy - in the muscles.
This process increases your fitness endurance while reducing the risk of obesity.
Now, a team from the University of South Carolina have revealed that a regular gym session could sharpen the mind in exactly the same way.
They have found that regular treadmill sessions also give a boost to the cell's powerhouses in the brain.
Research leader, Dr Mark Davis said this energy boost helped the brain to work faster and more efficiently.
"The evidence is accumulating rapidly that exercise keeps the brain younger," the Daily Mail quoted Dr Davis as telling Scientific American.
In the short term he said this could reduce mental fatigue and sharpen your thinking in between gym sessions.
He added that building up a large reservoir of mitochondria in the brain could also create a 'buffer' against age-related brain diseases such as Alzheimer's.he researchers came to their conclusions after a study, published in The Journal of Applied Physiology, on a group of mice.
Half of the mice were exercised on a small treadmill for half an hour a day while the other half were left to lounge in their cages.
Unsurprisingly they found after eight weeks that the running mice could exercise for 126 minutes before they tired, while the sedentary mice could only manage 74 minutes.
However, tissue samples revealed the running mice also had a surge in mitochondrial development in the brain, with evidence of both new mitochrondria and increased signaling between the brain cells.
Dr Davis said although it was an animal study, it was reasonable to assume the same process 'occurs in human brains'.
He added that a 30-minute jog was the human equivalent to the workout that the mice completed.