Hormonal

Robust skeletal muscle hypertrophy in humans requires satellite cell-mediated myonuclear addition, as expansion of the myonuclear domain beyond a threshold (~2,000 µm²) triggers the demand for new nuclei to support continued growth.

If you are struggling to add muscle size despite consistent training, your body may not be activating enough satellite cells to add new nuclei to your muscle fibers. This is often a genetic or 'non-responder' trait. To overcome this, you may need to focus on maximizing mechanical tension and recovery to stimulate the satellite cell pool, as simply training harder might not bypass this biological ceiling without the cellular machinery to support it.