Running as many as 15 miles a week could help to lower a person's risk of dying of Alzheimer's disease.
Researchers from the Lawrence Berkeley Laboratory in Berkeley, California discovered that walking for the same distance could also have beneficial effects, WebMD reports.
However, it must be noted that the study did not analyse whether or not these forms of exercise reduced the likelihood of developing the neurodegenerative disorder - only the chance of dying from it.
Staff scientists Paul Williams and his team looked at more than 153,000 runners and walkers who have been taking part in the National Runners' and Walkers' Health Studies since the beginning of the 1990s.
The participants were tracked for nearly 12 years and, throughout this timeframe, 175 people died from the disease.
Those who ran more than 15.3 miles every week had a 40 per cent lower chance of dying from Alzheimer's.
"Exercise seems to prevent the shrinkage [in the brain] that occurs with age," Mr Williams said.
He added that vigorous amounts of exercise could slash the death risk because it helps to preserve the brain volume.
In addition, it transpired that taking statins - cholesterol-lowering drugs - could lower the chances of death from the degenerative condition. Eating three or more pieces of fruit each day had similar beneficial effects.
As with exercise, this study did not examine if eating fruit regularly or taking statins was linked to a drop in the risk of experiencing this form of cognitive decline.
The full findings of this research can be viewed in the Journal of Alzheimer's Disease.
Guidance on how to reduce the risk of dementia generally tends to follow the thought process of whatever is good for your heart is also good for your brain. So, exercising regularly could help to ward off the chances of the disease, as could eating well, quitting smoking, drinking alcohol in moderation and keeping your blood pressure and cholesterol in order.
Read more about Barchester's dementia care homes