When cells age, their telomeres become shortened and frayed. A sedentary lifestyle, smoking, and obesity can accelerate that process.
Researchers at the University of California San Diego School of Medicine conducted a study of almost 1,500 women aged 64 to 95. Women who sat for over 10 hours a day and participated in little physical activity had cells that were biologically older by 8 years when compared to women who were more active.
Telomeres are the tiny caps on the ends of DNA strands that shorten with age. They protect chromosomes from deteriorating. A sedentary lifestyle, smoking, and obesity can accelerate that process.
The study concluded that sedentary women who followed the national recommended guidelines of physical activity and received at least 30 minutes a day of exercise didn't have shortened telomere length.
Reference:
Aladdin H. Shadyab et al. Associations of Accelerometer-Measured and Self-Reported Sedentary Time With Leukocyte Telomere Length in Older Women. American Journal of Epidemiology, January 2017