The January 28, 2008 issue of the American Medical Association journal Archives of Internal Medicine reported a study conducted by researchers in England and the U.S. which found that leisure time physical activity is associated with increased leukocyte (white blood cell) telomere length compared with that of sedentary individuals.
Telomeres are repeated DNA sequences which cap the ends of chromosomes and progressively shorten with age. According to the researchers, "Oxidative stress enhances telomere erosion with cell replication, whereas inflammation entails an increase in turnover of leukocytes. Telomere dynamics in leukocytes might, therefore, chronicle the cumulative burden of oxidative stress and inflammation and, as such, serve as an index of biological age."
Lynn F. Cherkas, PhD, of King’s College London, and colleagues evaluated questionnaire responses from 2,401 twins, who provided information on medical history, smoking habits, socioeconomic status, and physical activity level over the past 12 months. Blood DNA samples were evaluated for leukocyte telomere length. They found, as expected, a decrease in length corresponding to the age of the participants, averaging a 21 nucleotide yearly loss. Subjects who engaged in less leisure time physical activity had shorter telomeres than those who reported greater activity. Mean telomere length in the most active participants, who performed an average of 199 minutes of weekly physical activity, was 200 nucleotides greater than subjects whose activity was lowest at 16 minutes per week. This increase in telomere length corresponds with a biological age of a sedentary person up to ten years younger. Adjustment for age, physical activity at work, body mass index, and other factors failed to reduce the significance of the finding. A separate analysis which compared pairs of twins with differing levels of physical activity resulted in a similar finding.
The discovery contributes to the known benefits of exercise, including reduced rates of cardiovascular disease, type 2 diabetes, cancer, hypertension, obesity and osteoporosis. “A sedentary lifestyle increases the propensity to aging-related disease and premature death,” the authors remark. “Inactivity may diminish life expectancy not only by predisposing to aging-related diseases but also because it may influence the aging process itself.”
“Adults who partake in regular physical activity are biologically younger than sedentary individuals," the authors write. "This conclusion provides a powerful message that could be used by clinicians to promote the potential anti-aging effect of regular exercise.”
Commenting on such biomarkers as telomere length in an accompanying editorial, Jack M. Guralnik, MD, PhD of the National Institutes on Aging concluded that “Altering oxidative stress, inflammation, or other detrimental processes could have a measurable effect on these markers and ultimately on clinically relevant aging outcomes."
BACKGROUND: Physical inactivity is an important risk factor for many aging-related diseases. Leukocyte telomere dynamics (telomere length and age-dependent attrition rate) are ostensibly a biological indicator of human aging. We therefore tested the hypothesis that physical activity level in leisure time (over the past 12 months) is associated with leukocyte telomere length (LTL) in normal healthy volunteers. METHODS: We studied 2401 white twin volunteers, comprising 2152 women and 249 men, with questionnaires on physical activity level, smoking status, and socioeconomic status. Leukocyte telomere length was derived from the mean terminal restriction fragment length and adjusted for age and other potential confounders. RESULTS: Leukocyte telomere length was positively associated with increasing physical activity level in leisure time (P< .001); this association remained significant after adjustment for age, sex, body mass index, smoking, socioeconomic status, and physical activity at work. The LTLs of the most active subjects were 200 nucleotides longer than those of the least active subjects (7.1 and 6.9 kilobases, respectively; P= .006). This finding was confirmed in a small group of twin pairs discordant for physical activity level (on average, the LTL of more active twins was 88 nucleotides longer than that of less active twins; P= .03). CONCLUSIONS: A sedentary lifestyle (in addition to smoking, high body mass index, and low socioeconomic status) has an effect on LTL and may accelerate the aging process. This provides a powerful message that could be used by clinicians to promote the potentially antiaging effect of regular exercise.
Cherkas LF, Hunkin JL, Kato BS, Richards JB, Gardner JP, Surdulescu GL, Kimura M, Lu X, Spector TD, Aviv A. The association between physical activity in leisure time and leukocyte telomere length. Arch Intern Med. 2008 Jan 28;168(2):154-8. PMID: 18227361 [PubMed - indexed for MEDLINE]
Comment in: Arch Intern Med. 2008 Jan 28;168(2):131-2.
Reprinted in part with exclusive permission of LEF.