Leading a sedentary lifestyle may make us genetically old before our time, a study suggests.
A study of twins found those who were physically active during their leisure time appeared biologically younger than their sedentary peers.
The researchers found key pieces of DNA called telomeres shortened more quickly in inactive people. It is thought that could signify faster cellular ageing.
The King's College London study appears in Archives of Internal Medicine. An active lifestyle has been linked to lower rates of cardiovascular disease, type 2 diabetes and cancer. However, the latest research suggests that inactivity not only makes people more vulnerable to disease, but may actually speed up the ageing process itself.
The King's team studied 2,401 white twins, asking them to fill out questionnaires on their level of physical activity, and taking a blood sample from which DNA was extracted. They particularly focused on telomeres, the repeat sequences of DNA that sit on the ends of chromosomes, protecting them from damage. As people age, their telomeres become shorter, leaving cells more susceptible to damage and death.
Examining white blood cells from the immune system in particular, the researchers found that, on average, telomeres lost 21 component parts - called nucleotides - every year. But men and women who were less physically active in their leisure time had shorter leukocyte telomeres compared to those who were more active.
The average telomere length in those who took the least amount of exercise - 16 minutes of physical activity a week - was 200 nucleotides shorter than those who took the most exercise - 199 minutes of physical activity a week, such as running, tennis or aerobics.
The most active people had telomeres of a length comparable to those found in inactive people who were up to 10 years' younger, on average.
Direct comparison of twins who had different levels of physical activity produced similar results.
Source - BBC