- Telomeres are tiny caps found on ends of DNA strands that protect the chromosomes from deterioration.
- Telomeres naturally shorten as the cell ages.
- New study shows that shortening of telomeres is accelerated in elderly women with lower levels physical activity and higher sedentary time of 10 hours or more.
- Such women have biologically older cells compared to women who are less sedentary and more physically active.
Elderly women who sit for more than 10 hours a day with low physical activity have cells that are biologically older by eight years compared to women who are less sedentary.
The study found that elderly women with less than 40 minutes of moderate-to-vigorous physical activity per day and who remain sedentary for more than 10 hours per day have shorter telomeres.
Telomeres are tiny caps found on the ends of DNA strands. They protect chromosomes from deterioration.
Shortened telomeres are associated with cardiovascular disease, diabetes and major cancers.
"Our study found cells age faster with a sedentary lifestyle. Chronological age doesn't always match biological age," said Aladdin Shadyab, PhD, lead author of the study with the Department of Family Medicine and Public Health at UC San Diego School of Medicine.
Shadyab and his research team believe they are the first to objectively measure how the combination of sedentary time and exercise can impact the aging biomarker.
For the study, nearly 1,500 women participated. They were older white and African-American women from the Women's Health Initiative (WIH), aged 64 to 95 years.
WIH is a national, longitudinal study investigating the determinants of chronic diseases in postmenopausal women.
The participants had to complete questionnaires and wore an accelerometer on their right hip for seven consecutive days during waking and sleeping hours to track their movements.
The results showed that in older women, who exercised less, the telomere length was significantly smaller.
Even after adjustment for covariants, demographic characteristics, lifestyle behaviors, and body mass index, the results remained the same.
Women who sat longer did not have shorter telomere length if they exercised for at least 30 minutes a day.
"Discussions about the benefits of exercise should start when we are young, and physical activity should continue to be part of our daily lives as we get older, even at 80 years old." said Shadyab.
Future studies will examine how exercise relates to telomere length in younger populations and in men.
The study by researchers from University of California San Diego School of Medicine is published online in the American Journal of Epidemiology.
- Aladdin Shadyab et al. Associations of Accelerometer-Measured and Self-Reported Sedentary Time With Leukocyte Telomere Length in Older Women. American Journal of Epidemiology; (2017) DOI: https:doi.org/10.1093/aje/kww196