The exercise has to be ‘high-intensity’, as the researchers called it, such as running, aerobics or calisthenics. Low-intensity exercises, including yoga or walking, didn’t have the same protective benefits for the over-65s.

Researchers from the University of Miami looked at the benefits of various types of exercise on a group of 876 people who were over the age of 65. Their memory and thinking skills were assessed at the beginning of the study, and again, seven years later.

Just 10 per cent of the group was doing any sort of high-intensity exercise regularly; the rest were doing low-intensity or no exercise at all. Those from the high-intensity exercise group could remember more words from a list and carry out more simple tests than could those in the low-activity or no-activity groups. The difference was equivalent to a brain that was 10 years younger, the researchers said.