Want Bigger Muscles? This Misunderstood Rule Is Key, According to Andrew Huberman

Aiming for gains? It might be time to adopt Henneman Size Principle.

That’s straight from Andrew Huberman, Ph.D., a neuroscientist, Stanford professor, and podcaster. In his latest episode of “Huberman Lab Essentials,” he describes how the Henneman size principle can promote bigger muscles.

Related: Andrew Huberman: This One Gym Rule Can Prevent Muscle Loss As You Age

First: What is the Henneman size principle? It’s a foundational principle of muscle physiology that explains how the body recruits motor units (or nerve-muscle connections) in a stair-step pattern from low to high threshold. This means your body starts by using smaller, low-force motor units for light tasks and progressively recruits larger, high-force units as effort increases. As effort increases, so does muscle strength and size.

This principle is “badly misunderstood” in some bodybuilding and exercise physiology communities, says Huberman. “Many people have come to interpret it by saying that the way to recruit high threshold motor units, the ones that are hard to get to, is to just use heavy weights,” he says. “That’s actually not the case.”

Huberman says you don’t need lift all heavy weights all the time to recruit these high-threshold units. Sustained effort and fatigue can achieve the same effect, which is key for muscle growth and strength.

To maintain and build muscle, Huberman says, aim for five sets per week with weights within 30 to 80 percent of your max threshold. These should feel like “moderately light to heavy” weights.

There is a benefit to lifting heavy weights to the point of failure in 10 percent of your workout, Huberman says. Beyond that, it isn’t necessary. If you get in those five sets of moderate lifts per week, “you can greatly increase muscle hypertrophy muscle size and/or muscle strength if that’s what you want to do,” says Huberman.

Related: Andrew Huberman Swears By This One Weird Exercise for Boosting Power and Mobility