What is muscle memory and is it real?

The answer

Muscle memory operates through two distinct mechanisms. The neural component involves the formation and strengthening of motor neuron pathways in the cerebellum, basal ganglia, and motor cortex through repeated practice, eventually allowing complex movements (like riding a bicycle or playing piano) to be executed automatically without conscious thought. The cellular component involves myonuclei: when muscles are trained, satellite cells fuse with muscle fibers, donating additional nuclei that persist even during periods of detraining and atrophy. These extra nuclei allow previously trained muscles to regrow faster than untrained muscles when exercise resumes, a phenomenon confirmed by studies showing that myonuclear addition through training is essentially permanent. This is why people who were once fit can regain strength faster than beginners.