Skeletal muscle growth early in life is ‘remembered’ by the genes in the muscle, helping them to grow larger later in life.
The study found that genes in skeletal muscle have less DNA epigenetic modifications in response to exercise and throughout periods of inactivity (ie. injury). This allows the muscle to grow even bigger following exercise again later.
This study has many implications but one interesting implication is that if you lose muscle you’re epigenetically primed to get it back.
The study has several methodological flaws. The main is that the authors didn’t correct their p-values for multiple testing. I did the FDR estimation manually based on p-values from the supplementary tables, and the smallest FDR was approximately 0.2.
Probably this study should be taken with a pinch of salt, to say it mildly; at least it doesn’t prove anything.
Another important implication is that if people in midlife exercise regularly and build muscle, they can more easily regain lost muscle mass in older age.