In young men, low-load high-volume resistance exercise performed to muscular failure (30% 1RM) increases myogenin mRNA expression by 204% at 24 hours post-exercise compared to work-matched low-load resistance exercise without failure, indicating that exercise to failure, independent of volume, is responsible for the observed upregulation of myogenin mRNA.

When muscles are worked with light weights until exhaustion, the repeated contractions create intense internal stress that turns on a signaling pathway starting with Erk1/2, which then activates mTOR to boost the production of a protein called myogenin. This protein tells muscle stem cells to mature and add new nuclei to muscle fibers, allowing the muscle to keep building protein for hours after the workout.