Cycling or jogging in middle age can protect people against a stroke, new research shows.
In fact, regular exercise in your 40s could leave your brain with the blood vessels of a 16 year old by your 70s.
And this may lessen the severity of a potentially deadly blood clot in old age, scientists claim, reports DailyMail.
During a stroke, tissue damage can be limited because of the body's DIY mechanism that kicks in.
A network of "collateral vessels" allows blood flow to be rerouted when arteries narrow.
But they shrink as the brain ages, and vary greatly in size and number from one person to the next.
Around the world, researchers are developing ways to boost these vessels, paving the way for new treatments that could combat a host of illnesses.
But now a study has shown a simple lifestyle change in midlife could improve the outlook, without the need for drugs.
Using mice, researchers from the University of North Carolina found this loss of collateral vessels is prevented by exercise.
They said the amount of damage to the brain after a stroke and the effectiveness of recovery treatments depend significantly on the extent of collateral circulation.
Collaterals are small blood vessels running alongside the main coronary arteries.
They work in a similar way to water trickling along tributaries around a blocked stream.
Lab rodents that started exercising regularly at 12 months old had the same abundance of collateral vessels when they reached 25 months as seen at three months.
In human years, this would be equivalent to beginning regular aerobic exercise, such as cycling or jogging, at 40 and at 70 finding these life saving vessels were as good as when they were 16.
When the exercising 25 month old mice suffered strokes, their brains were still in as good a shape as young, three month old mice.
The exercising mice also had higher levels of molecules that help blood vessels work properly and remain healthy.
Their non-exercising 25 month old counterparts had fewer collaterals of smaller diameter.
Study author Dr James Faber said the findings suggest regular aerobic exercise may protect the collateral circulation and lessen the severity of strokes later in life.
The findings were presented at the American Heart Association's International Stroke Conference in Houston.