Mixed

Resistance training induces an acute and chronic expansion of the satellite cell (SC) pool in skeletal muscle, but this expansion does not result in a detectable increase in myonuclear content during the first 10 weeks of training in young, previously trained men.

If you are a young, previously trained man, expect your satellite cells to increase in number during the first few months of resistance training, but do not expect this to immediately translate into more muscle nuclei. Your muscle is likely adapting through increased protein synthesis and repair mechanisms rather than structural nuclear addition at this stage. Focus on consistent training; the nuclei may add up if you train long enough or intensely enough to exceed current transcriptional capacity.