To be clear, it’s not the genetic code we’re talking about… but the DNA molecules within muscles are chemically and structurally altered in big ways.
Those changes take place in stretches of DNA that are involved in turning ‘on’ genes important for muscles' adaptation to exercise. The modifications appear to be early events in the genetic reprogramming of muscle for strength and, ultimately, in the structural and metabolic benefits of exercise.
"We often say, ‘You are what you eat.’ Well, muscle adapts to what you do,” says study researcher Juleen Zierath of Karolinska Institutet in Sweden. “If you don't use it, you lose it, and this is one of the mechanisms that allows that to happen.”
Thigh muscle samples taken from 14 sedentary men and women after a burst on the exercise bike bear fewer chemical marks on DNA – specifically methyl groups – than they did before exercising.
- As New Scientist explains, such demethylation allows genes to more easily make proteins, which suggests that more proteins involved in the breakdown of fat are being made after exercise.
- The scientists homed in on metabolic genes that tend to be expressed in lower levels in type 2 diabetics, and within 3 hours of exercise, promoters for these genes lost their methyl marks, The Scientist reports.
“This shows that there is some molecular evidence to support that notion that exercise is a medicine,” Zierath says.
ADDITIONALLY, the study suggests that caffeine might also influence muscle in the same way (losing methyl groups)… perhaps the new findings point the way to medicines with similar benefits for those who can’t exercise. However, Nature reports:
Zierath cautions that this result does not imply that drinking coffee could be a replacement for exercise. Caffeine acts mainly through the central nervous system, and to see direct effects on muscle such as those in the rodent-cell experiments, “one would need to consume a caffeine equivalent of about 50 cups per day, almost close to a lethal dose”, she says. “Exercising is far easier if you ask me.”
The work was published in Cell Metabolism yesterday.
Image by ch_77 via Flickr
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