Less time sitting down was associated with longer telomeres - caps at the ends of chromosomes that protect DNA from damage. Standing up often may be more effective than regular exercise in slowing the cellular ageing process, the study reports.
Longer telomeres are associated with a healthier lifestyle and diet, and a longer lifespan. Shortening of telomeres is thought to increase the risk of age-related illnesses such as heart disease and some cancers.
Researchers at the Karolinska University Hospital in Sweden recruited 49 men and women aged 68 who were overweight and led a mostly sedentary lifestyle. The participants were randomly assigned to an exercise regime, or given no instruction about exercise. Their physical activity was measured by pedometer recordings, lifestyle questionnaires and a daily diary. Telomere length was measured from blood samples at the start of the study and after six months.
The study found that after six months, maintenance of telomere length was associated with reduced sedentary activity, such as sitting down, in the exercise group. However, the researchers found no link between telomere length and the amount of exercise or physical activity that participants in either group undertook.
'We're excited about this study', Professor Mai-Lis Hellenius, who led the research published in the British Journal of Sports Medicine, told Medscape. 'Long telomeres are linked to a longer, healthier life'.
The researchers recognise that the study is small and hope to repeat the study on a larger scale - in different groups of people, looking at effects of other tissues in the body, such as muscle and fat tissue.
'In many countries formal exercise may be increasing, but at the same time people spend more time sitting. There is growing concern that not only low physical activity level in populations, but probably also sitting and sedentary behaviour, is an important and new health hazard of our time', said the study authors.Professor Hellenius told Medscape: 'Our DNA will be damaged during a lifetime. It's damaged by bad diets, smoking, infections, and so on. Our capability to copy and produce new DNA and new cells is so important'.