A recent scientific study revealed that skeletal muscles maintain a kind of “molecular record” of previous periods of inactivity, and that this record’s effect differs between young and elderly groups.
Muscle lethargy
While young muscles show greater flexibility and ability to adapt to repeated periods of cessation of movement, aging muscles appear more susceptible to deterioration and are negatively affected by renewed cessation of movement.
This research was led by Adam Sharpless from the Norwegian Institute of Sports Sciences, where his team followed a group of young volunteers who underwent periods of leg immobilization, in addition to elderly mice to test the effect of aging.
The results showed that the young men’s muscles lost mass each time, but the genetic response associated with energy production was less severe the second time around, suggesting the presence of a kind of “protective memory.”
In contrast, the muscles of aged mice recorded greater deterioration in the second period of inactivity, with a noticeable decrease in the activity of genes related to “mitochondria,” responsible for energy production, and an increase in stress signals and DNA repair.
The researchers also observed permanent changes in DNA methylation, which are chemical markers that regulate gene activity, that remained even after the pauses ended.
These signs have been associated with a decreased ability of muscles to produce energy, especially in older people.
The study, published in the journal Advanced Science, suggests that rehabilitation should not treat every setback as a new beginning, but rather should take into account previous history of inactivity.
Researchers believe that enhancing the “energy molecule NAD+” or designing customized training programs may help mitigate some of the harmful effects stored within the muscles with age.
