People who are physically active in their free time may
be biologically younger than couch potatoes, a new British
"A sedentary lifestyle increases the propensity
to aging-related diseases and premature death. Inactivity
may diminish life expectancy not only by predisposing
to aging-related diseases, but also because it may influence
the aging process itself," study author Lynn F. Cherkas,
College London, said in a prepared statement.
The researchers looked at the physical activity levels,
smoking habits and socioeconomic status of 2,401 white
twins. The researchers also collected DNA samples from
participants, and examined the length of telomeres-repeated
sequences at the end of chromosomes in white blood cells
(leukocytes). Leukocyte telomeres shorten over time and
may serve as a marker of a person's biological age.
Overall, the study participants had an average telomere
loss of 21 nucleotides (structural units) per year. But
those who were more active in their leisure time had longer
leukocyte telomeres than those who were less active.
"Such a relationship between leukocyte telomere
length and physical activity remained significant after
adjustment for body-mass index, smoking, socioeconomic
status and physical activity at work," the authors
"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."
Oxidative stress damage caused to cells by exposure to
oxygen and inflammation may be a factor contributing to
shorter telomere length in sedentary people. Stress has
also been linked to telomere length. Exercise may reduce
stress and its effect on telomeres and the aging process,
the study authors suggested.
"The U.S. guidelines recommend that 30 minutes of
moderate-intensity physical activity at least five days
a week can have significant health benefits," they
wrote. "Our results underscore the vital importance
of these guidelines. They show that adults who partake
in regular physical activity are biologically younger
than sedentary individuals. This conclusion provides a
powerful message that could be used by clinicians to promote
the potential anti-aging effect of regular exercise."
But more research is needed to confirm a direct link
between physical activity and aging, the study added.
"Persons who exercise are different from sedentary
persons in many ways, and although certain variables were
adjusted for in this analysis, many additional factors
could be responsible for the biological differences between
active and sedentary persons, a situation referred to
by epidemiologists as residual confounding," Dr.
Jack M. Guralnik, of the U.S. National Institute on Aging,
wrote in an accompanying editorial.
"Nevertheless, this article serves as one of many
pieces of evidence that telomere length might be targeted
in studying aging outcomes," he added.
The study was published in the Jan. 28 issue of the Archives
of Internal Medicine.