14 DAY TRIAL // Muscles remember their former fitness even when they atrophy from lack of use, as this memory is stored as DNA-containing nuclei, that develop when a muscle is exercised, a new research published online August 16 in the Proceedings of the National Academy of Sciences reports.
This research sustains the fact that exercise in early life could help reduce frailness in elder people and questions the time that doping athletes are banned from competition, according to Kristian Gundersen, a physiologist at the University of Oslo in Norway and leader of the study.
For this study, scientists simulated the effects of working out on a muscle that helps lift the toes in mice, by making it work harder than usual, and found out that the number of nuclei increased from day six.
In 21 days, the number of nuclei in each fiber cell increased by 54 percent because of the hard-working muscle, and starting on the ninth day, muscle cells also started to pump up, increasing their volume by 35 percent.
The important thing about this discovery is that now scientists know that the nuclei come first and muscle mass adds up later.
In another experiment, scientists worked out the mice's muscle for two weeks and then affected the nerves that led to the muscle, atrophying the tissue.
This only affected the volume of the cells as they deflated to near 40 percent, but did not modify the number of nuclei within the cells, Wired Science reports.
Gundersen said that muscle cells are huge and so, it takes more than one nucleus to supply the DNA templates that make large amounts of the proteins that give muscle its force.
The findings contradict the belief that muscle cells die during atrophy, as Gunderson’s team discovered that there is apoptosis going on but that it does not affect muscle fibers or their extra nuclei.
The nuclei resist for at least three months in mice, a lot of time for their relative short life, but Gunderson says that does not yet know “if it lasts forever, but it seems to be a very long-lasting effect.”
Bengt Saltin, a muscle physiologist at the University of Copenhagen in Denmark says that “that’s fascinating thinking, and there’s nice proof in this article to support it; it’s really novel and helps to explain descriptive findings that muscles are quick to respond upon further training.”
This study contradicts many peer-reviewed published data and it may provoke discontentment among several researchers, says Lawrence Schwartz, a cell biologist at the University of Massachusetts Amherst.
If human bodies respond the same as mice, this might be problematic for establishing the time period during which steroid-taking athletes are suspended, because as Gundersen says, “if you have nuclei that last forever, then you would also have an advantage that could last forever.”