We all know testosterone has a pretty stacked resume: muscle growth, libido, mood regulation, bone density—the hormone wears many hats. But here’s the kicker: according to a newly published cross-sectional study analyzing 4,495 adult men from the NHANES dataset (2011–2014), testosterone might not play the role in strength we thought it did. Muscle mass? Yes, there’s a clear link. Strength? Not so much.

Now, if you’re a guy aged 20 to 59 wondering how much your T-levels affect your gains in the gym, this research brings some nuance—and even a few surprises.

Let’s break down what this means for men’s health, athletic performance, and how we think about muscle.

Testosterone 101: A Brief Refresher

Before we dive into the nitty-gritty of this hormone’s relationship with muscle, let’s take a step back. What exactly is testosterone doing behind the scenes—and why has it long been hailed as the ultimate muscle-building molecule?

What testosterone does in your body

Testosterone is the principal male sex hormone, produced primarily in the testicles. It influences:

• Muscle protein synthesis

• Libido and sexual performance

• Energy levels

• Fat distribution

• Red blood cell production

And of course—muscle development. It works at the cellular level, promoting the activity of satellite cells (the muscle stem cells responsible for repair and growth), while inhibiting fat cell differentiation.

The assumption: more testosterone = more strength

This has been the prevailing belief. But newer research, including this recent NHANES analysis, shows we need to separate the concept of muscle size from muscle function. They’re not always the same.

The New Study: Key Findings

This recent study, published in Frontiers in Physiology, examined men between the ages of 20–59 and found that:

• Testosterone levels were positively associated with muscle mass (ALMBMI)

• Testosterone levels were not significantly associated with muscle strength (grip strength)

For women, the story was different altogether—no significant associations with either muscle mass or strength.

Let’s unpack the details.

Muscle Mass vs. Muscle Strength: What’s the Difference?

Muscle mass (ALMBMI)

Measured using dual-energy X-ray absorptiometry (DXA), appendicular lean mass (ALM) refers to the total muscle in the arms and legs. ALMBMI adjusts this measure relative to body size.

Muscle strength (GSMAX)

Assessed using a handgrip dynamometer. While a decent proxy for general strength, it doesn’t tell the whole story about dynamic movements or athletic performance.

This is important: strength depends not just on the size of your muscles, but also on neuromuscular efficiency—how well your brain and nervous system activate your muscles.

What the Data Actually Says

• 

  Higher total testosterone was significantly linked with higher ALMBMI in men.

• Men in the top testosterone quartile had an 80% lower risk of low muscle mass compared to those in the bottom quartile.

• But when it came to grip strength, the correlation wasn’t statistically significant.

Graphs and modeling confirmed:

• A linear dose-response curve between testosterone and muscle mass

• No similar pattern with grip strength

Why Testosterone Boosts Mass But Not Strength

This finding isn’t as strange as it seems when you look under the hood. On the surface, it feels counterintuitive—shouldn’t more testosterone lead to more power? But when you zoom in on how the human body works, especially the nervous system, it becomes clear why these two variables don’t always go hand in hand.

Strength is more than just size

• Neurological control: Strength relies heavily on the central nervous system’s ability to recruit motor units effectively. Even with massive muscles, poor neural drive will limit how much force you can exert. That’s why elite powerlifters train not just for muscle growth, but also for neurological efficiency.

• Muscle fiber type: Type II (fast-twitch) fibers are essential for explosive strength. These fibers respond well to strength training but deteriorate with age more rapidly than Type I fibers. While testosterone can help with hypertrophy, it doesn’t guarantee retention of fast-twitch function.

• Mitochondrial dysfunction: Strength isn’t just about contractile power; it’s about how quickly and efficiently muscles can use energy. Aging diminishes mitochondrial efficiency, which compromises power output—even when mass is preserved.

• Coordination and motor learning: Your ability to lift heavier weights doesn’t solely depend on your muscles, but also on how practiced you are at engaging them. Movement patterns, joint alignment, and firing sequences all matter.

• Muscle quality vs. quantity: It’s not just how much muscle you have—it’s what’s in that muscle. Intramuscular fat infiltration, inflammation, and poor capillarization can reduce muscle quality. Testosterone helps quantity, not necessarily quality.

Training matters

Testosterone might build more muscle tissue, but if you’re not training specifically for strength (like heavy resistance work, low reps, explosive movements), you’re not optimizing function. The type of training you engage in rewires your neuromuscular pathways. A guy with lower testosterone who trains correctly might out-lift someone with higher testosterone who just does hypertrophy work. Strength requires specificity. Period.

Also, consider recovery. Testosterone influences recovery speed, but sleep, stress, and nutrition are just as vital. Without these, any gains from elevated testosterone—natural or supplemented—can be dulled or even lost entirely.