Editor’s Note: This is a guest article by Reese Dockrey.

Things don’t always go as planned in the life of a lifter. On a long enough timeline, it’s guaranteed that some unforeseen event will interrupt your training. Maybe it’s an injury that sidelines your workouts for several weeks. Or you have a baby, and suddenly there’s no time to get “the pump” on for a few months. Or there’s a worldwide pandemic that forces your gym to shut down for an extended period of time.

Then, in the following weeks, the consequences kick in: you start losing the gains you worked so hard to build, and you begin shrinking down to your old self. Maybe you pick up a basic bodyweight routine at home, but you know that pushups and lunges won’t be enough to replace a barbell and squat rack.

When this happens, a lot of guys go into panic mode, understandably. The fear of knowing that you have to “use it or lose it” sets in. Even when you’re finally able to get back into the gym, you remember how hard it was to build up your body, and you dread the thought of having to do it all over again.

Thankfully, the situation isn’t so dire. The fact is, guys who lose muscle are typically able to gain it all back quickly, i.e., you’re not starting from square one. Before diving into how this works, let’s take a quick refresher on how you were able to build all of that muscle in the first place. Here’s the CliffsNotes version:

Strength training with heavy weights puts a stress on your body, which stimulates a response that “tells” your body to adapt to the stress by getting bigger and stronger.You recover from that stress via diet—with lots of calories and protein—and plenty of rest.As you recover, you experience “hypertrophy,” which is an increase in the size and/or density of individual muscle fibers.

The Key to Your Comeback: “Muscle Memory”

In strength training, “muscle memory” has long been understood as the body’s ability to “remember” certain movements. Basically, as you build muscle, your neural networks get more efficient at moving heavy loads in specific patterns. When you stop working out for a while (aka “detrain”), you lose some of that strength. Then, when you resume lifting (even years later), like remembering how to ride a bike, you quickly recover your nervous system “gains.”

Even your DNA remembers. A 2018 study found that, even after detraining for several weeks (and potentially years), your “epigenetic” ability for hypertrophy isn’t lost, i.e., if you get swole once and lose it, you can get swole more easily the second time around. 

Then there’s your muscle cells and their multiple nuclei — called “myonuclei” — which are sort of the “control centers” of the cell. Each myonuclei can handle only a certain amount of muscle within the cell, so for the muscle cell to continue to grow over time, it needs more myonuclei. When you train, your individual muscle fibers acquire these additional myonuclei from nearby “satellite cells,” and BOOM, you get massive pecs and traps. In a 2010 study of mice, researchers at the University of Oslo discovered that after you stop your workouts and your muscles atrophy, those additional myonuclei tend to stick around — potentially for years.

That’s all to say: you’ve already done the hardest part!

Simply put, adding more myonuclei to your muscle fibers and strengthening your nervous system is like upgrading your car with a new engine. It was a Honda