How Exercise Affects Your Genes, and
More
February 13, 2015
Story at-a-glance
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Brief, vigorous exercise causes immediate structural and
chemical changes in the DNA molecules within your muscles
that benefit your health
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Endurance training also produces beneficial genetic changes
that play a role in energy metabolism, insulin response, and
muscle inflammation
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Increased blood flow from regular exercise adapts your brain
to turn different genes on or off; many of these changes
help protect against diseases such as Alzheimer’s and
Parkinson’s
By Dr. Mercola
Virtually everyone would agree that exercise improves health, but
the mechanisms by which it actually produces those benefits have
been challenging to tease out.
Fitness research has come a long way though, and modern science
has made a number of interesting observations that help explain how
exercise affects your body
to improve your health.
Part of the answer lies in its ability to affect genetic
expression; activating some genes, and deactivating others. A
previous New York Times article1
delved into the latest research on this front, noting that:
“The human genome is astonishingly complex and dynamic,
with genes constantly turning on or off, depending on what
biochemical signals they receive from the body. When genes are
turned on, they express proteins that prompt physiological
responses elsewhere in the body.”
The Epigenetics of Exercise
Far from being “written in stone,” genetic expression can be
altered by influences coming from outside the gene. This influence
alters the operation of the gene, but does not affect the DNA
blueprint itself. This process is known as “epigenetics,” and occurs
mainly through methylation. As described in the featured article:
“In methylation, clusters of atoms, called methyl groups,
attach to the outside of a gene like microscopic mollusks and
make the gene more or less able to receive and respond to
biochemical signals from the body.”
Methylation patterns can be altered by a variety of lifestyle
changes, such as diet and exercise. Toxic exposure also tends to
affect genetic expression, by altering the types of proteins a
particular gene will express.
In this way, your environment, diet, and general lifestyle play a
significant role in your state of health and development of disease.
When it comes to exercise, previous research has found that exercise
can induce immediate changes in the methylation patterns of
genes found in your muscle cells.
A study published in the journal Cell Metabolism2
in 2012 showed that while the underlying genetic code in the muscle
remains unchanged, vigorous exercise—even if brief—causes structural
and chemical changes in the DNA molecules within the muscles.
This gene activation is induced by contraction of the muscle,
and this contraction-induced gene activation appears to be part of
the chain of events that lead to the genetic reprogramming of muscle
for strength—and to the structural and metabolic benefits of
exercise.
Several of the genes affected by an acute bout of exercise are
genes involved in fat metabolism. Specifically, the study suggests
that when you exercise, your body almost immediately experiences
genetic activation that increases the production of fat-busting
proteins.
Previous studies have also identified and measured a wide variety
of biochemical changes that occur during exercise. More than 20
different metabolites3
are affected, including compounds that help stabilize your blood
sugar. All of these biochemical changes create a positive feedback
loop, resulting in improved health and physical performance.
How Endurance Training Affects Your Genes
These kinds of findings led to another question: does endurance
training (opposed to a brief intense bout of exercise) also affect
methylation, and if so, how? A Swedish study4
published in December 2014 sought to shed light on this question.
As reported in the featured article:
“[S]cientists at the Karolinska Institute in Stockholm
recruited 23 young and healthy men and women, brought them to
the lab for a series of physical performance and medical tests,
including a muscle biopsy, and then asked them to exercise half
of their lower bodies for three months.
One of the obstacles in the past to precisely studying
epigenetic changes has been that so many aspects of our lives
affect our methylation patterns, making it difficult to isolate
the effects of exercise from those of diet or other behaviors.
The Karolinska scientists overturned that obstacle by the
simple expedient of having their volunteers bicycle using only
one leg, leaving the other unexercised.
In effect, each person became his or her own control
group. Both legs would undergo methylation patterns influenced
by his or her entire life; but only the pedaling leg would show
changes related to exercise.”
The volunteers performed their one-legged pedal exercise, at a
moderate pace, for 45 minutes four times a week for three months.
The result? The exercised leg was stronger than the unexercised leg,
confirming that exercise led to physical improvement, as you would
expect.
Genetic alterations within the cells of the muscles revealed
there was more to the story however. More than 5,000 sites on the
muscle cells’ genome, biopsied from the exercised leg, had altered
methylation patterns. These changes were not found in biopsied cells
from the unexercised leg. A majority of the methylation changes that
occurred in the exercised leg play a role in:
- Energy metabolism
- Insulin response
- Muscle inflammation
Endurance Training versus High Intensity Exercise
Quite clearly, exercise—in all its forms—tends to have a positive
effect. It has the power to affect your entire body, and your
overall state of health. Its beneficial impact on your insulin
response (normalizing your glucose and insulin levels by optimizing
insulin receptor sensitivity) is among the most important benefits
of exercise, as insulin resistance is a factor in most chronic
disease. According to lead author Malene Lindholm:5
“Through endurance training — a lifestyle change that is
easily available for most people and doesn’t cost much money—we
can induce changes that affect how we use our genes and, through
that, get healthier and more functional muscles that ultimately
improve our quality of life.”
High intensity interval training (HIIT) has been shown to be far
more effective at producing positive results however, when compared
to endurance training. And while the study above concluded that
endurance training indeed induces genetic alterations that promote
good health, HIIT is known to do so far more efficiently. Mounting
research shows that by focusing on endurance-type exercises, such as
jogging on a treadmill, you actually forgo many of the most profound
benefits of exercise.
Some of the latest research in high intensity exercise involves
myokines—a class of cell-signaling proteins produced by muscle
fibers—and how they can combat diseases like metabolic syndrome and
cancer. I interviewed Dr. Doug McGuff about this research last year.
These myokines—which are cytokines produced in muscle—are very
anti-inflammatory. They also increase your insulin sensitivity and
your glucose utilization inside the muscle.
High intensity strength training, also known as “super-slow
strength training,” is likely the most effective in terms of
activating myokines.
The reason for this is because it induces a rapid and deep level
of muscle fatigue. This triggers the synthesis of more contractile
tissue, and all the metabolic components to support it—including
more myokines. If you still have not incorporated high intensity
exercise into your fitness regimen, I highly recommend getting
started. You can
learn more about HIIT here,6
as there are many different programs to choose from. I also review
the similarities and differences between
super-slow and super-super-slow strength training techniques in
this previous article.7
The Many Biological Effects of Exercise
Getting back to the effects of exercise in general, a number of
biological effects occur when you work out. This includes changes in
your:
- Muscles, which use glucose and ATP for
contraction and movement. To create more ATP, your body needs
extra oxygen, so breathing increases and your heart starts
pumping more blood to your muscles. Without sufficient oxygen,
lactic acid will form instead. Tiny tears in your muscles make
them grow bigger and stronger as they heal.
- Lungs. As your muscles call for more oxygen
(as much as 15 times more oxygen than when you’re at rest), your
breathing rate increases. Once the muscles surrounding your
lungs cannot move any faster, you’ve reached what’s called your
VO2 max—your maximum capacity of oxygen use. The higher your VO2
max, the fitter you are.
- Heart. As mentioned, your heart rate
increases with physical activity to supply more oxygenated blood
to your muscles. The fitter you are, the more efficiently your
heart can do this, allowing you to work out longer and harder.
As a side effect, this increased efficiency will also reduce
your resting heart rate. Your blood pressure will also
decrease as a result of new blood vessels forming.
- Joints and bones, as exercise can place as
much as five or six times more than your body weight on them.
Peak bone mass is achieved in adulthood and then begins a slow
decline, but exercise can help you to maintain healthy bone mass
as you get older. Weight-bearing exercise is actually one of the
most effective remedies against
osteoporosis, as your bones are very porous and soft, and as
you get older your bones can easily become less dense and hence,
more brittle -- especially if you are inactive.
Exercise Is Important for Optimal Brain Health, Too
Mounting research also shows that exercise is as important for
your brain function as it is for the rest of your body. In fact, it
may be part and parcel of staying “sharp as a tack” well into old
age. For starters, the increased blood flow allows your brain to
almost immediately function better. As a result, you tend to feel
more focused after a workout. More importantly though, exercising
regularly will prompt the growth of new brain cells. In your
hippocampus, these new brain cells help boost memory and learning.8
It also helps preserve both gray and white matter in your
brain, which prevents cognitive deterioration that can occur with
age.9,10
Genetic changes occur here, too. The increased blood flow adapts
your brain to turn different genes on or off, and many of these
changes help protect against diseases such as Alzheimer’s and
Parkinson’s. A number of neurotransmitters are also triggered, such
as endorphins, serotonin, dopamine, glutamate, and GABA. Some of
these are well-known for their role in mood control. Not
surprisingly, exercise is one of the most effective prevention and
treatment strategies for
depression. Three of the mechanisms by which exercise produces
these beneficial changes in your brain are:
- Increasing Brain Derived Neurotrophic Factor (BDNF).
Exercise stimulates the production of a protein called FNDC5,
which in turn triggers the production of BDNF, which has
remarkable rejuvenating abilities. In your brain, BDNF both
preserves existing brain cells,11
and activates brain stem cells to convert into new neurons,
effectively making your brain grow larger.12
- Decreasing BMP and boosting Noggin:
Bone-morphogenetic protein (BMP) slows down the creation of new
neurons, thereby reducing neurogenesis. If you have high levels
of BMP, your brain grows slower and less nimble. Exercise
reduces the impact of BMP, so that your adult stem cells can
continue performing their vital functions of keeping your brain
agile.
In animal research,13,14
mice with access to running wheels reduced the BMP in their
brains by half in just one week. In addition, they also had a
notable increase in another brain protein called Noggin, which
acts as a BMP antagonist. So, exercise not only reduces the
detrimental effects of BMP, it simultaneously boosts the more
beneficial Noggin as well. This complex interplay between BMP
and Noggin appears to be yet another powerful factor that helps
ensure the proliferation and youthfulness of your neurons.
- Reducing plaque formation: By altering the
way damaging proteins reside inside your brain, exercise may
help slow the development of Alzheimer's disease.15
Exercise Leverages Other Healthy Lifestyle Changes
While diet accounts for about 80 percent of the health benefits
you get from a healthy lifestyle, exercise is the ultimate
“leveraging agent” that kicks all those benefits up a notch. The
earlier you begin and the more consistent you are, the greater your
long-term rewards, but it’s never too late to start. Even seniors
can improve their physical and mental health—not to mention physical
function—by starting up an appropriate exercise program.
Strength training is particularly important for the elderly, and
super-slow strength training tends to be both safer and more
effective than many other alternatives.
I believe that, overall, high-intensity
interval training really helps maximize the health benefits of
exercise, while simultaneously being the most efficient and
therefore requiring the least amount of time. That said, ideally
you’ll want to strive for a varied and well-rounded fitness program
that incorporates a wide variety of exercises.
I also strongly recommend
avoiding sitting as much as possible, and making it a point to walk
more every day. A fitness tracker can be very helpful for this. I
suggest aiming for 7,000 to 10,000 steps per day, in addition to
your regular fitness regimen, not in lieu of it. The research is clearly
showing that prolonged sitting is an independent risk factor for chronic
disease and increases your mortality risk from all causes. So
standing up more and engaging in non-exercise movement as much as
possible is just as important for optimal health as having a regular
fitness regimen.
© Copyright 1997-2015 Dr. Joseph Mercola. All Rights Reserved.
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