(BBC News) Doing lots of exercise in older age can prevent the immune system from declining and protect people against infections, scientists say.
They followed 125 long-distance cyclists, some now in their 80s, and found they had the immune systems of 20-year-olds.
Prof Norman Lazarus, 82, of King's College London, who took part in and co-authored the research, said: "If exercise was a pill, everyone would be taking it.
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"It has wide-ranging benefits for the body, the mind, for our muscles and our immune system."