Men and women who enagage in jogging for 40 to 30 minutes respectively each day for five days a week may be able to slow down their biological clocks by nine years, say researchers.

The study showed that adults with high levels of physical activity are likely to have their biological age decreased by nine years over those who are sedentary and seven years compared to those who are moderately active."We all know people that seem younger than their actual age. The more physically active we are, the less biological ageing takes place in our bodies," said Larry Tucker, Professor at Brigham Young University in the US."If you want to see a real difference in slowing your biological ageing, it appears that a little exercise won't cut it. You have to work out regularly at high levels," Tucker added. 

In the study, published in the medical journal Preventive Medicine, the team analysed data from 5,823 adults.Women who engaged in 30 minutes of jogging per day and men who engaged in 40 minutes, for five days a week in consistently high levels of physical activity have significantly longer telomeres.Telomeres are the protein endcaps of our chromosomes which are extremely correlated with age. The older we get, the shorter our telomeres.

The shortest telomeres came from sedentary people -- they had 140 base pairs of DNA less at the end of their telomeres than highly active folks, the researchers said.Although the exact mechanism for how exercise preserves telomeres is unknown, Tucker noted that it may be tied to inflammation and oxidative stress."We know that regular physical activity helps to reduce mortality and prolong life, and now we know part of that advantage may be due to the preservation of telomeres," Tucker said.