When healthy but inactive people exercise for a matter of minutes, it triggers a rather immediate change to their DNA, which may ultimately make them stronger, a new study has revealed.
The underlying genetic code in human muscle isn`t changed with exercise, but the DNA molecules within those muscles are chemically and structurally altered in very important ways.
Those modifications to the DNA at precise locations appear to be early events in the genetic reprogramming of muscle for strength and, ultimately, in the structural and metabolic benefits of exercise.
`Our muscles are really plastic,` said Juleen Zierath of Karolinska Institutet in Sweden.
`We often say `You are what you eat.` Well, muscle adapts to what you do. If you don`t use it, you lose it, and this is one of the mechanisms that allows that to happen.`
The DNA changes in question are known as epigenetic modifications and involve the gain or loss of chemical marks on DNA over and above the familiar sequence of As, Gs, Ts, and Cs.
The new study shows that the DNA within skeletal muscle taken from people after a burst of exercise bears fewer chemical marks (specifically methyl groups) than it did before exercise.
Those changes take place in stretches of DNA that are involved in turning `on` genes important for muscles` adaptation to exercise.
When the researchers made muscles contract in lab dishes, they saw a similar loss of DNA methyl groups.
Epigenetic modifications that turn genes on and back off again can be incredibly flexible events. They allow the DNA in our cells to adjust as the environment shifts.
`Exercise is medicine,`` Zierath added, and it seems the means to alter our genomes for better health may be only a jog away.
The study has been published in Cell Metabolism, a Cell Press publication.