How exercise in old age prevents the immune system from declining

Doing lots of exercise in older age can prevent the immune system from declining and protect people against infections, scientists say.

Researchers 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.”

“It has wide-ranging benefits for the body, the mind, for our muscles and our immune system.”

The research was published in the journal Aging Cell.

Prof Janet Lord, director of the Institute of Inflammation and Ageing, at the University of Birmingham, and co-author of the research, said:

“The immune system declines by about 2-3%, a year from our 20s, which is why older people are more susceptible to infections, conditions like rheumatoid arthritis and potentially, cancer.”

“Because the cyclists have the immune system of a 20-year-old rather than a 70- or 80-year-old, it means they have added protection against all these issues.”

The researchers looked at the markers in the blood for T-cells, which help the immune system respond to new infections. These are produced in the thymus, a glad in the chest, which normally shrinks in size in adulthood.

They found that the endurance cyclists were producing the same level of T-cells as adults in their 20s, whereas a group of inactive older adults were producing very few.

The researchers also believe that being physically active in old will help people respond better to vaccines, and so be better protected against infections such as flu.

Steve Harridge, co-author and professor of physiology at King’s College London, said: “Being sedentary goes against evolution because humans are designed to be physically active.”

"You don't need to be a competitive athlete to reap the benefits - or be an endurance cyclist - anything which gets you moving and a little bit out of puff will help."

Prof Harridge and Prof Lazarus believe that highly physically active older people represent the perfect group in which to analyse the true effects of biological ageing.