now appears that physically active people have cells that look
younger at the molecular level than those that are sedentary showing
changes in Telomere length
involving more than 2,400 British twins, found for the first
time that exercise appears to slow the shortening of telomeres.
cap the ends of chromosomes, the structures that carry genes.
Every time a cell divides, the telomeres get shorter. When
the telomeres get too short, the cell can no longer divide
Association Between Physical Activity in Leisure Time and
Leukocyte Telomere Length
A group of 2,401 white twins
was studied by Tim D. Spector, a professor of genetic epidemiology
at King's College London, and colleagues and was published in
the Archives of Internal Medicine. The team administered questionnaires
related to physical activity level, smoking habits, and social
and economic factors. The participants also
provided a blood sample, and DNA was extracted from the white
blood cells (leukocytes.) The leukocyte DNA samples were analyzed
for the length of their telomeres at each end of the chromosomes.
Spector and his colleagues analyzed the telomeres from white blood
cells collected from participants examining whether there was
a relationship between the subjects' telomere length and how much
exercise they got in their spare time over a 10-year period.
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). " Source
who did a moderate amount of exercise -- about 100 minutes a week
of activity such as tennis, swimming or running -- had telomeres
that on average looked like those of someone about five or six
years younger than those who did the least -- about 16 minutes
a week. Those who did the most -- doing about three hours a week
of moderate to vigorous activity-- had telomeres that appeared
to be about nine years younger than those who did the least. As
the amount of exercise increased, the telomere length increased.
researchers conclude that a sedentary lifestyle (in addition to
smoking, high body mass index, and low socioeconomic status) has
an effect on telomere length and may accelerate the aging process.
This can provides a powerful message that could be used by clinicians
to promote the potentially antiaging effect of regular exercise.
A telomere is a region of repetitive DNA at the end of chromosomes,
which protects the end of the chromosome from destruction.
During cell division, the enzymes that duplicate the chromosome
and its DNA can't continue their duplication all the way
to the end of the chromosome.
If cells divided without telomeres, they would lose the
end of their chromosomes, and the necessary information
it contains. (In 1972, James Watson named this phenomenon
the "end replication problem.") The telomere is a disposable
buffer, which is consumed during cell division and is replenished
by an enzyme. This mechanism usually limits cells to a fixed
number of divisions, and animal studies suggest that this
is responsible for aging on the cellular level and affects
Telomeres protect a cell's chromosomes from fusing with
each other or rearranging. These chromosome abnormalities
can lead to cancer, so cells are normally destroyed when
telomeres are consumed. Most cancer is the result of cells
bypassing this destruction. Biologists speculate that this
TELOMERES ARE SHOWN AS THE WHITE CAPS AT THE END OF CHROMOSOMES
IN THE ABOVE IMAGE.