January 28, 2008
Sedentary Lifestyles Age Chromosome Telomeres Faster

Telomere caps on chromosomes shrink more quickly in people who do not get much exercise.

Individuals who are physically active during their leisure time appear to be biologically younger than those with sedentary lifestyles, according to a report in the January 28 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

Regular exercisers have lower rates of cardiovascular disease, type 2 diabetes, cancer, high blood pressure, obesity and osteoporosis, according to background information in the article. “A sedentary lifestyle increases the propensity to aging-related disease and premature death,” the authors write. “Inactivity may diminish life expectancy not only by predisposing to aging-related diseases but also because it may influence the aging process itself.”

Lynn F. Cherkas, Ph.D., of King’s College London, and colleagues studied 2,401 white twins, administering questionnaires on physical activity level, smoking habits and socioeconomic status. The participants also provided a blood sample from which DNA was extracted. The researchers 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.

We are losing 21 nucleotides (DNA letters) per year off the ends of our chromosomes. I miss my fallen nucleotides.

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, socioeconomic status and physical activity at work,” the authors write. “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.” A sub-analysis comparing pairs in which twins had different levels of physical activity showed similar results.

199 minutes of physical activity per week: Can you manage that? Thats almost 20 minutes per day.

Of course there are caveats to keep in mind when thinking about a study like this one. Are less healthy people less able to exercise? Do they have less energy to exercise? Which way does the direction of causation flow? Also, does shorter telomere length really indicate shorter life expectancy? Still, there's a strong chance that this study's most obvious interpretation is correct: exercise slows aging.

I'm inclined toward believing the most obvious interpretation because of other work done on telomeres and aging. Toward that end see some of my other posts on telomere lengths and aging: Chronic Stress Accelerates Aging As Measured By Telomere Length, Telomere Length Indicates Mortality Risk, Telomeres Shorten Quicker If You Have Less Vitamin D, and Telomere Shortening Linked To Osteoarthritis.

Share |      Randall Parker, 2008 January 28 08:03 PM  Aging Exercise Studies

tvoh said at January 28, 2008 8:20 PM:

Did you see the post on GNXP2 questiong the efficacy of Vitamin d?

Randall Parker said at January 28, 2008 9:00 PM:

A link to Razib's post would help.

My reaction: The evidence being proposed to overturn conventional wisdom on vitamin D seems a pretty small result. Then does sunshine deliver its apparent benefits via some other mechanism? Or does the type of vitamin D matter? Also, this researcher needs to address a pretty big body of evidence on vitamin D and health and explain some errors in it before I dismiss it all so easily.

Obesity: So many factors have been argued as its cause. Vitamin D making people fat? Lots of obese people don't drink milk. How are they getting the vitamin D?

Also, we really are getting less vitamin D from sunshine as people have shifted to cubicle jobs. So it isn't clear how skin-produced vitamin D could be causing obesity either.

John said at January 29, 2008 6:34 AM:

That would be almost 30 minutes a day, no? 7x30 = 210

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