How Is Muscle Built? The Real Science of Hypertrophy | Elevate Fitness

Created by Derick Dinh on June 27, 2025

Share This Blog

Facebook Reddit X WhatsApp Email

💪 If you’ve ever been told that building muscle is about “tearing it down so it grows back bigger,” you’ve been sold an outdated myth.

For decades, gym culture has been built on the idea that muscle damage causes growth — but modern research paints a very different picture.

In reality, muscle is built through tension, not trauma. Growth doesn’t come from destroying muscle fibers — it comes from signaling your body to adapt.

This post dives deep into the science of hypertrophy, explaining how mechanical tension and protein turnover drive muscle growth, and why the microtear myth needs to be left behind.

Weightlifting for Muscle Growth

🧬 Muscle Is Always Changing — Not Static

Your muscles are constantly being remodeled. Every day, your body is breaking down old or damaged proteins (via muscle protein breakdown, or MPB) and building new ones (via muscle protein synthesis, or MPS).

This dynamic process means your muscle mass is never “set” — it’s always in flux:

  • If MPS > MPB, your muscles grow
  • If MPB > MPS, your muscles shrink
  • If MPS = MPB, your muscle mass remains stable

Hypertrophy occurs when, over time, you consistently tip the scale in favor of synthesis over breakdown — and the main stimulus for that is mechanical tension.

Mechanical Tension

⚙️ What Is Mechanical Tension?

Mechanical tension is the force a muscle experiences when it’s stretched and contracted under load — especially when that tension is generated voluntarily by the nervous system and maintained through high-effort repetitions.

There are two types:

  • Passive tension: From stretching the muscle (e.g., during the eccentric phase)
  • Active tension: From forcefully contracting the muscle (especially near failure)

Together, they create the primary stimulus for hypertrophy — especially when a muscle is under load, in a lengthened position, contracting with effort, and taken close to failure.

🧪 How Tension Triggers Muscle Growth

When a muscle is exposed to high levels of mechanical tension, it activates mechanosensors inside the muscle fibers — likely located in the sarcolemma and costameres.

These sensors begin a process called mechanotransduction, which converts mechanical signals into molecular ones, leading to the activation of the mTORC1 pathway — the central switch for muscle protein synthesis.

Key Players in the Signaling Process:

  • mTORC1: Master regulator of cell growth
  • p70S6K and 4E-BP1: Translation regulators activated by mTORC1
  • IGF-1 and AKT: Sometimes involved upstream, though less critical

Once activated, your body ramps up MPS, producing proteins like myosin heavy chains and actin — the contractile components of muscle fibers.

🔄 Muscle Growth Is About Protein Turnover, Not Destruction

The misconception that muscles grow from microtears comes from a misunderstanding of post-exercise soreness and inflammation.

Some muscle damage may occur during training — particularly during unfamiliar movements or heavy eccentrics — but muscle damage is a side-effect, not the stimulus for growth.

Why the microtear theory is wrong:

  • Studies (Damas et al., 2016) show that in early training phases, muscle damage is high, but hypertrophy is low.
  • Excessive damage shifts resources toward repair, not growth, reducing net MPS.
  • Soreness (DOMS) is linked to inflammation, not muscle growth.

âś… What Actually Matters for Hypertrophy

To maximize muscle growth, focus on:

  • High mechanical tension
  • Sufficient proximity to failure
  • Sustained elevations in MPS across weeks and months
  • Recoverable training volume

Muscle protein synthesis is transient, peaking for ~24–36 hours post-workout and returning to baseline without further stimulus. Regular, tension-based training keeps MPS elevated, leading to cumulative growth.

🧠 Why Effort Matters More Than Anything

According to the effective reps theory, the final 4–5 reps before failure produce the most growth, when the muscle is fully recruited, tension is highest, and fatigue forces maximal effort.

It doesn’t matter if you’re doing 6 reps or 20 — if you’re not approaching failure, you’re not generating enough tension to maximize growth.

Effort in Training

❌ Debunking Muscle Growth Myths

Myth Reality
You grow when muscle fibers tear. Muscle damage is not required for growth — and may reduce MPS.
Soreness means it’s working. Soreness is a sign of inflammation, not adaptation.
You need to feel the burn to grow. Metabolic stress plays a minor role — tension and effort matter more.
Heavy weight is the key to size. Load only matters if effort and tension are high.
More volume means more growth. Volume only helps if it’s recoverable and contains effective sets.

🚀 Summary: How Is Muscle Actually Built?

Concept Role in Growth
Mechanical Tension Primary stimulus for hypertrophy — activates mTOR and MPS
Effective Reps (0–3 RIR) Recruit full motor units, maximize mechanical stress
mTOR Pathway Activation Initiates synthesis of new muscle proteins
Protein Turnover Balance of MPS > MPB drives long-term hypertrophy
Muscle Damage Unnecessary; excess damage slows growth by redirecting recovery
Recovery & Nutrition Support ongoing MPS and allow repetition of stimulus

Final Thought:

Muscle doesn’t grow because it’s torn apart. It grows because it’s given a reason to adapt. That reason is mechanical tension — applied with effort, repeated with consistency, and supported by recovery.

Train hard. Rest well. Trust the science — and leave the microtear myth behind.