Individuals who lead sedentary lifestyles during their leisure time appear to be biologically older than those who are physically active, say researchers.
The study, led by Lynn F. Cherkas, Ph.D., of King's College London, stated that a sedentary lifestyle increases the propensity to aging-related disease and premature death.
"A sedentary lifestyle increases the propensity to aging-related disease and premature death. Inactivity may diminish life expectancy not only by predisposing to aging-related diseases but also because it may influence the aging process itself," the authors said.
In the study, the researchers analysed 2,401 white twins, administering questionnaires on physical activity level, smoking habits and socio-economic status. The participants also provided a blood sample from which DNA was extracted.
The research team examined the length of telomeres, repeated sequences at the end of chromosomes, in the twins' white blood cells (leukocytes). Leukocyte telomeres progressively shorten over time and may serve as a marker of biological age.
The analysis found that telomere length decreased with age, with an average loss of 21 nucleotides (structural units) per year.
Men and women who were less physically active in their leisure time had shorter leukocyte telomeres than those who were more active.
"Such a relationship between leukocyte telomere length and physical activity level remained significant after adjustment for body mass index, smoking, socio-economic status and physical activity at work," the authors said.
"The mean difference in leukocyte telomere length between the most active [who performed an average of 199 minutes of physical activity per week] and least active [16 minutes of physical activity per week] subjects was 200 nucleotides, which means that the most active subjects had telomeres the same length as sedentary individuals up to 10 years younger, on average," they added.
The study is published in Archives of Internal Medicine, one of the JAMA/Archives journals.