Prior training can accelerate muscle growth even after extended idleness


Date:
August 18, 2021
Source:
University of Arkansas
Summary:
Skeletal muscles in mice appear to 'remember' prior training, aiding
muscle growth and adaptability when retrained through exercise.



FULL STORY ========================================================================== According to a report by the American Psychological Association published
in February 2021, 42% of American adults reported unintended weight gain
since the COVID-19 pandemic began, averaging about 29 pounds.


==========================================================================
For those who are still struggling to get back on track with
their exercise routine, there is encouraging news: new research
from the University of Arkansas indicates that prior training of
muscles can accelerate muscle growth and response even after extended
idleness. Getting back what was lost is likely easier than most people
realize.

Kevin Murach, an assistant professor in the Department of Health, Human Performance, and Recreation, recently conducted research that supports
this. In "Nucleus Type-Specific DNA Methylomics Reveals Epigenetic
'Memory' of Prior Adaptation in Skeletal Muscle," published in the
American Physiological Society's flagship journal Function, Murach and
his colleagues found that previously trained muscles in mice responded
with more sensitivity, and grew more rapidly, than previously untrained muscles.

Further analysis revealed that the muscles, and specifically the DNA
of the muscle cells themselves, retained a kind of cellular memory
of previous adaptation to exercise. More technically stated, "Muscle
nuclei have a methylation epi-memory of prior training that may augment
muscle adaptability to retraining." Muscle Memory in Cells Murach and
his team studied the skeletal muscles of mice, which were trained on a progressively weighted wheel over a period of 8 weeks to build muscles,
then taken off the wheel for 12 weeks, or "detrained." This was followed
by a four-week period of retraining. These mice were then compared
against a control group that was only trained for four weeks. Findings indicated that the previously trained cohort saw accelerated gains in
muscle growth after retraining when compared to the control group, and
that specific epigenetic changes to DNA methylation persisted after the original training.



========================================================================== Murach thinks these findings point to an epigenetic explanation of
muscle memory.

To many people, the term "muscle memory" evokes a motor skill, like
throwing a Frisbee or riding a bike, that is acquired through repetition
and honed to the point it can be done with little conscious thought
or effort. But what if muscle memory runs deeper than the nervous
system? Murach wants to know if information from previous training can
be retained at the cellular level, in the DNA of a muscle cell. This is
what he means by an epigenetic explanation.

Murach explained, "Epigenetics is the idea of changing how a cell responds
to stimuli (i.e., alters the expression of genes) without altering the
genetic code. Cells can respond to things based on DNA without changing
the DNA, just changing how it's accessed. You can change the cellular
response without changing the genetic code." In short, when it comes
to exercise, a kind of rebound response may be stored in muscle cells
at the epigenetic level, which is what his study points to.

Anecdotally, most gym rats know that muscle acquired earlier in life is
easier to reacquire than new muscle. Put another way, someone who put on
10 pounds of muscle in college, then lost it when their kids were born,
likely finds it much easier to put that muscle back on than someone who
never had it to begin with.

But anecdotes aren't science, and a single study isn't definitive. Murach
is eager to learn more about what is happening on the molecular level.



========================================================================== Murach explained, "understanding the cues that enhance muscle
adaptability, specifically those at the epigenetic level, has consequences
for healthy gymgoers and athletes, as well as populations susceptible to
muscle dysfunction, such as those forced into inactivity as well as aged individuals." Murach's co-authors included Yuan Wen, Cory M. Dungan,
C. Brooks Mobley and Taylor Valentino from the University of Kentucky,
and Ferdinand Von Walden from the Karolinksa Institutet in Stockholm,
Sweden. This is Murach's first paper to be published as a faculty member
of the University of Arkansas, where he arrived in June of this year
and established the Molecular Muscle Mass Regulation Laboratory.

While there is a lot more to be learned about what's happening to muscles
on the cellular level, Murach thinks it's safe to conclude "it's better
to have worked out and lost muscle, than to have not worked out at all."
So if your exercise routine was disrupted by COVID-19, don't despair. Your cells may be in better shape than you realize.

========================================================================== Story Source: Materials provided by University_of_Arkansas. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Yuan Wen, Cory M Dungan, C Brooks Mobley, Taylor Valentino,
Ferdinand von
Walden, Kevin A Murach. Nucleus Type-Specific DNA Methylomics
Reveals Epigenetic 'Memory' of Prior Adaptation in Skeletal
Muscle. Function, 2021; DOI: 10.1093/function/zqab038 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210818130522.htm

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