What Drives Muscle Growth & What Doesn't | Dr. Mike Roberts

Skeletal muscle hypertrophy is primarily driven by mechanical tension, which triggers a cascade of molecular events including satellite cell activation and myonuclear accretion. While individual responses to resistance training vary, circulating hormone levels like testosterone are not reliable predictors of growth; instead, internal cellular factors such as ribosome content and satellite cell availability are more significant. Resistance training effectively promotes mitochondrial biogenesis, particularly in older, deconditioned individuals, challenging the long-standing myth that strength training is inherently detrimental to aerobic capacity. Strategies to optimize muscle growth include utilizing lengthened partials to maximize stretch under load and increasing training volume, while the "interference effect" between strength and endurance training can be minimized by utilizing high-intensity sprint interval training on a stationary bike to preserve recovery capacity and maintain high-threshold motor unit recruitment.