Muscle Maturity: What It Is + How To Achieve It

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Most people who enjoy lifting weights or strength training set performance-related goals, such as bench pressing your body weight in pounds or squatting 200 pounds.

However, if you’re a bodybuilder or motivated by changes in your physique, there’s a chance you’re striving for muscle maturity and wondering how to gain it, perhaps even without knowing what it is.

In this guide, we will answer basic questions like “What is muscle maturity?” and provide insight into how you achieve muscle maturity. 

We will take a look at: 

  • What Is Muscle Maturity?
  • What Does Muscle Maturity Look Like?
  • When Does Muscle Maturity Occur?
  • How to Gain Muscle Maturity


Let’s get started!

A muscular woman who has reaches muscle maturity.

What Is Muscle Maturity?

Muscle maturity is a concept that many runners have never heard of, but if you’re stepped into the bodybuilding world, it’s a term you’re probably familiar with.

When we think of our bodies, certain aspects seem relatively static once we finish puberty and enter adulthood. For example, our height remains relatively constant, and we tend to think of our bones and muscles as “full-grown” and relatively permanent, unchanging structures.

However, the cells in our bones, muscles and connective tissues are always turning over as they mature, die, and are replaced with new cells. As such, our muscles are living, dynamic structures that mature and evolve with training over time.

Muscle maturity does not refer to your muscular build when you finish puberty and have grown into your adult build. Rather, muscle maturity occurs much later on in adulthood as a product of years of strength training.

But what exactly is muscle maturity? In the bodybuilding sphere, muscle maturity refers to the state wherein your muscle fibers have thickened and are well defined, sculpted to look aesthetically the way you’d like them to and contract forcefully, enabling you to be in peak strength.

A muscular man posing.

Some people describe muscle maturity as the target or physique goal for all the years of strength training workouts and other forms of exercise in your fitness routine. It is when you have “mature muscle” or your muscular “prime.”

Even once you reach muscle maturity, your individual muscle fibers are still in a dynamic state of repairing and renewing, but your muscles have basically reached peak form and strength, having adapted and developed to their maximum capacity after years of training.

What Does Muscle Maturity Look Like? 

We still have yet to truly define muscle maturity aside from describing it as peak muscle appearance and function.

Part of the difficulty in defining muscle maturity is that it’s not a term used within scientific or health communities, so there’s a lack of quantifiable or discrete criteria used to define this state.

With that said, if you want to have a more tangible way to understand muscle maturity, it helps to think of the differing quality of muscle tissue.

Muscular density is one of the primary factors that distinguish a mature muscle from muscle tissue still in the process of maturing.

Any skeletal muscle is made up of muscle fibers, which are muscle cells bundled together in groups known as fascicles. Between these fascicles is connective tissue as well as some intramuscular fat.

A man doing a pull-up.

The denser your muscles, the higher the percentage of muscle fibers, meaning the muscle is leaner, with less fat tissue interwoven throughout.

Although somewhat of a crude analogy, think about cuts of meat at the deli counter. Meat is the muscle tissue of animals, so it’s similar to our own muscle.

When you visually examine cuts of meat, meat with more white marbling is fattier. It is also more tender, whereas the leaner cuts have very little intramuscular fat and are tougher and firmer.

Moreover, meat from younger animals (veal vs. beef or lamb vs. mutton, for example) tends to be more tender and fattier than meat from mature animals. This is due to a lower muscle density and a higher percentage of intramuscular fat.

With muscle maturity, you’re looking at a denser, firmer, tougher muscle with defined striations. In other words, muscle maturity is the lean beef or the tough mutton, while the young adult just getting started training has muscles like the juicier veal or lamb.

A woman performing a snatch.

When you achieve muscle maturity, your muscles are compact, firm, and formed from toughened muscle fibers with thickened myofibrils (the structural proteins that compose the muscle fibers) at the microscopic level.

Muscle maturity occurs when the muscle fibers cannot get any denser. They have reached their end-state peak density.

At the macroscopic level, muscle maturity is also usually characterized by a muscular build with very little body fat. 

For men, this is typically thought to be a body fat percentage of 5-10%, whereas females have more essential fat stores, so muscle maturity would be around a body fat percentage of 8-15%.

someone doing a bicep curl.

When Does Muscle Maturity Occur?

We know that skeletal maturity occurs at the end of puberty and peak bone mass occurs a little before age 30, but when do you reach muscle maturity?

Muscle maturity is a bit more of a nebulous concept, and there is significantly less scientific data to definitively report a specific age at which you reach your muscular peak.

Most bodybuilding experts say that most people achieve muscle maturity somewhere between the ages of 25-40 years old, depending on how old you were when you first started serious or formal strength training. 

Generally speaking, muscle maturity occurs after approximately 10-12 years of training, so if you started working out as young as 15, you can potentially achieve it by age 25, but it’s more common to see people aged 28-40 or so with this physique condition.

A man in a high plank position.

How to Gain Muscle Maturity

Like many of the finer things in life—or physical changes to your body as a result of exercise—muscle maturity takes time. It’s a long process that can’t be rushed. 

Well-rounded, total-body strength training workouts that employ gradual, progressive overload performed consistently over many years is the best way to train to achieve muscle maturity. 

Your workout routine should consist of a minimum of at least 2-3 total-body strength training workouts per week or 4-5 days of body part split routines.

The goal of these workouts should be to build muscular strength and size rather than muscular endurance. From a practical standpoint, this means lifting the heaviest weights you can safely handle with proper form for 4-10 reps per set rather than lighter weights for 12-15 reps or more.

Heavier loads trigger muscle hypertrophy, which refers to muscle building or the increase in muscle mass triggered by a cascade of various hormones and RNA factors that control protein synthesis. Through hypertrophy, your muscle fibers get bigger, stronger, and denser.

Compound, dynamic, multi-joint strengthening exercises like squats, lunges, deadlifts, step-ups, pull-ups and push-ups are some of the best exercises for building muscle mass.

A gym class of people squatting.

Muscle protein synthesis, or repairing and building new muscle tissue, also requires adequate protein intake, so it’s important that your diet includes an adequate amount of protein. There is evidence to suggest that the amino acid leucine is particularly crucial for muscle growth. 

Along with carbohydrates and fat, protein provides energy (4 kcals per gram), but it also aids in muscle recovery after strength training, helping heal any microscopic damage and building new muscle fibers to adapt to your training loads.

The American College of Sports Medicine recommends that athletes consume at least 1.2–2.0 grams of protein per kilogram of body weight per day. For example, if you weigh 154 pounds (70 kg), you should consume at least 84-140 grams of protein daily to meet your physiological needs.

While these recommendations are adequate for most athletes, one way to promote muscle growth is to increase your protein intake to at least 1-2 grams per pound of body weight.

While muscle maturity isn’t rooted in much scientific or medical evidence, the concept of progressing your muscles towards their physical peak through years of consistent training is certainly a theory that holds water and should help motivate you to keep at it, even on days when you don’t feel like working out.

If you are looking to begin strength training or want to ensure you are working out adequately to improve your running, check out the following guides:

Strength Training For Runners

Weightlifting For Runners

A man doing a bicep workout.

Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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