How Exercise Can
Change Your DNA
Scientists discover that physical
activity leads to beneficial changes in gene activity, even after a single
workout.
By Alice Park
Exercise does a
lot of good things — it burns calories, helps keep your weight in check and
lowers your risk of heart disease, stroke and diabetes. Now add one more thing
to the list: physical activity can change your DNA.
Unlike the
aberrations and genetic mutations caused by carcinogens and toxins, exercise-induced
alterations to DNA are more like tune-ups, helping muscles to work better and
more efficiently. What’s more, these changes occur even after a single
20-minute workout.
Juleen Zierath, a
professor of physiology at the Karolinska Institute in Stockholm, reports with her colleagues in the journal Cell Metabolism
about these very early changes that muscle cells undergo the first time you get
off the couch and into the gym. The researchers worked with a group of 14 young
men and women who were relatively sedentary, and asked them to work out on an
exercise bike that measured their maximum activity levels. The participants
also volunteered to give up a little bit of muscle, from their quadriceps, in a
relatively painless biopsy procedure performed under local anesthesia. The
researchers took the biopsy of muscle cells once before the participants
exercised, and again within 20 minutes afterward.
Using the biopsied
samples, researchers compared the activity in a series of muscle-related genes
before and after exercise. More genes were turned on in the cells taken after
the exercise and the participants’ DNA showed less methylation, a molecular process in which chemicals called methyl
groups settle on the DNA and limit the cell’s ability to access, or switch on,
certain genes. By controlling how
much methylation goes on in certain cells at specific times, the body regulates
which genes in the DNA are activated — that’s what differentiates the
development of an an eye cell, for example, from that of a liver cell.
Methylation also helps to prime muscle cells for a bout of exercise,
getting them to pump out the right enzymes and nutrients the muscle needs to
get energy and burn calories while you’re pounding the pavement during that
mile-long jog. “We are trying to get at the early
messages that the muscle is [receiving in order] to say, ‘Something is
happening here, we need to coordinate so we can get more enzymes and more
machinery on board so we can cope with the demands of this exercise,’” says
Zierath.
The more intense
the exercise, she says, the more the methyl groups are on the move. She and her team were able to see this firsthand by comparing gene
activity in participants who also agreed to exercise at two different
intensities over a period of a week. On one visit, they were asked to cycle
until they reached 40% of their maximum capacity; on another occasion,
they biked until they reached 80% of their maximum. The muscle
biopsies following the 80% sessions showed a lower concentration of methyl
groups — and therefore more RNA, which is the first byproduct of gene activity
— than samples taken after the 40% sessions.
MORE: Why Exercise
Won’t Make You Thin
To confirm the
role of exercise on gene expression in muscle, the scientists then studied how
calcium affected the entire system. When muscle cells start to gear up for
intense activity like exercise, they release calcium, which fuels the
contraction process. When the scientists blocked calcium production, the
effect disappeared, and the muscles didn’t contract as much.
That’s when Zierath
threw in some coffee — or more specifically, caffeine. Caffeine triggers the
release of calcium, and can enhance the way methyl groups move aside to turn on
the genes that help muscles contract. When she added caffeine to a lab dish
containing cells from the leg muscles of rats, the muscle cells showed lower
concentrations of methyl groups and more mRNA — a similar effect as seen after
exercise — as she expected.
But, says Zierath,
that doesn’t mean you can skip the workout for a cup of coffee instead. “Most
of the physiological effect of the caffeine we drink is on the central nervous
system, and not dispersed to all the muscles,” she says. “In order to get the
same kind of effect we saw in the cells, you would have to drink 50 cups of
coffee a day, which is close to the lethal dose. In my mind, half an hour of
moderately high intensity exercise is sufficient to do the same thing.”
Alice Park is a
writer at TIME. Find her on Twitter at @aliceparkny . You can
also continue the discussion on TIME’s Facebook page
and on Twitter at @
Read more: http://healthland.time.com/2012/03/07/how-exercise-can-change-your-dna/?xid=newsletter-weekly#ixzz1ow4Er9QW
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