London: People who exercise regularly appear to be biologically younger than those who lead sedentary lifestyles, scientists have found.

Inactivity not only leads to a greater risk of ageing-related diseases, but it may also influence the ageing process itself, researchers believe.

A study of twins found there was a difference of about nine years of ageing between those who exercised regularly and those who did not, even after considering other influences including body mass index (BMI), smoking and socio-economic status (SES).

Researchers at King’s College London and in the US studied ageing in 2,401 twins by analysing telomeres, which cap the end of chromosomes in cells and protect them from damage.

Telomeres shorten with age, leaving people increasingly susceptible to cell damage which causes disease.

However there is considerable variation between individuals, and recent research has also linked lifestyle factors such as smoking and obesity with shorter than average telomeres.

Those who exercise regularly are already known to be at lower risk of cardiovascular disease, type 2 diabetes, cancer, high blood pressure, obesity and osteoporosis.

Comparing twins who were raised together but did different amounts of exercise, the researchers found that on average the telomeres were significantly longer in the more active twin.

The study concluded: “The US guidelines recommend that 30 minutes of moderate-intensity physical activity at least five days a week can have significant health benefits.

“Our results underscore the vital importance of these guidelines. They show that adults who partake in regular physical activity are biologically younger than sedentary individuals.”