One kind of muscle memory

Why is it easier to get back in shape than it is to get into shape in the first place? Every who has ever worked hard on their fitness is well aware of this phenomenon. A new study (Schwartz) offers a surprising explanation.

Some adaptations to muscle training are temporary and vanish quickly if you don’t keep working out. But others, like the addition of extra muscle nuclei, appear to be more or less permanent. Nuclei are added as you train so that they can build and manage more proteins in a plumper muscle cell. When you stop training, the cell slowly deflates — atrophies — but the nuclei helpfully remain, dormant, waiting until you are ready to exercise again.

Very cool. Yet another reason to regularly give your muscles jobs to do. See Alex Hutchinson’s more detailed analysis of the study.