The study challenges the idea that muscles go back to their starting condition when you stop strength training.
“Our findings suggest that there are permanent structural changes in the muscle,” says Gundersen. “We don’t know if they’re really permanent, but they’re very long-lasting in animals, at least.”
The researchers put mice through strength training on their hind legs. Building muscle generates new muscle nuclei, which Gundersen calls the “small factories that will produce new muscle.” Then the researchers took the mice off their training regimen.