About this episode

In this episode, Layne Norton discusses the fundamentals of muscle growth and the training variables that drive hypertrophy.

How do muscles actually grow — and what really matters for hypertrophy? In this episode, I break down muscle growth from the ground up, starting with muscle structure and working all the way through the practical training variables that actually drive hypertrophy. We cover how muscle fibers are built, why muscle cells are uniquely multi-nucleated, and how satellite cells and myonuclei influence growth potential and long-term adaptations (including the concept of “muscle memory”). From there, we dig into how resistance training shifts net protein balance, why muscle protein synthesis and breakdown both rise with training, and why hypertrophy is often delayed when people first start lifting. A major focus of this episode is mechanotransduction — how mechanical loading from resistance training is converted into chemical signals that stimulate muscle growth. We unpack what we know (and don’t know) about mTOR signaling, phosphatidic acid, kinase pathways, and why mechanical tension is the primary driver of hypertrophy. From there, the episode gets highly practical. We break down: • Why proximity to failure matters more than load • How volume really works (and why “dose-dependent”…

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