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Sedentary lifestyle may accelerate biological aging
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Elderly women who exercised little and sat for more than 10 hours per day had cells that were biologically older by 8 years in comparison to women who were less sedentary, according to a study published in American Journal of Epidemiology.
“Telomeres are repetitive DNA-protein structures located at the ends of chromosomes that protect and maintain chromosomal stability and integrity,” Aladdin H. Shadyab, PhD, MS, MPH, CPH, of the department of family medicine and public health at University of California, San Diego School of Medicine, and colleagues wrote. “Telomeres progressively shorten with age, leading to cellular senescence and apoptosis. Shortened leukocyte telomere length (LTL) has been associated with cardiovascular disease, type 2 diabetes, and major cancers.”
Between 2012 and 2013, Shadyab and colleagues performed a cross-sectional study to evaluate the association of sedentary time with LTL and determine whether such associations varied by physical activity level. They enrolled 1,481 older white (58.3%) and black (41.7%) women between the ages of 64 and 95 years (average age, 79.2 years) from the Women’s Health Initiative in the study. Sedentary time was measured through self-reported questionnaires and data from accelerometers worn by the participants to track their movements for an average of 14.7 hours per day for nearly 7 consecutive days. Multiple linear regression models were used to assess the association between sedentary time and LTL.
Data indicated that the mean amount of accelerometer-measured sedentary time was 9.2 hours per day and the mean amount of self-reported sedentary time was 8.6 hours per day. In addition, the mean amount of accelerometer-measured moderate-to-vigorous physical activity was 0.8 hours per day and self-reported physical activity and the mean amount of self-reported moderate-to-vigorous physical activity was 0.5 hours per day.
There was a significant association between accelerometer-measured sedentary time and LTL after adjusting for wear time only. Conversely, there was no association between self-reported sedentary time and LTL. In addition, significantly shorter LTL was observed in women at or below the median level of accelerometer-measured moderate-to-vigorous physical activity who were also in the highest quartile of accelerometer-measured sedentary time compared with those in the lowest quartile, after adjustment for demographic characteristics, lifestyle behaviors and health-related factors (average difference, 170 base pairs).
Overall, based on the accelerator measurements, higher amounts of sedentary time may be linked to shorter LTL, or faster aging, among women who are less physically active, according to the researchers.
“Our study found cells age faster with a sedentary lifestyle,” Shadyab said in a news release. “Chronological age doesn’t always match biological age.”
“We found that women who sat longer did not have shorter telomere length if they exercised for at least 30 minutes a day, the national recommended guideline,” he added. “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.”
Additional studies have found that prolonged sitting time is associated with obesity in men and one hour of physical activity offsets the increased risk of death from sitting. – by Alaina Tedesco
Disclosure: The researchers report no relevant financial disclosures.