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The Only Proven Mechanisms of Hypertrophy / Muscle Growth (Backed By Research)

Finally, a clear cut answer on how to build muscle! (backed by research).

If you are reading this, chances are you want to add some muscle mass, fast.

The question you may have is some variation of “What will make my muscles grow best?”

If you…

Ask the powerlifter, and you will get the response, “It’s all about heavy weight”.

Ask someone at the gym, and you will get the response “You’ve got to train a lot and break down your muscles”.

Ask Arnold Schwarzenegger, and he will tell you, “You gotta chase the pump”.

Ask me and I will tell you, you have to combine all three.

Let me explain.

In 2010, a highly respected researcher Brad Schoenfeld, released a paper that highlighted the mechanisms of muscle hypertrophy…..or simply, WHAT MAKES MUSCLES GROW (Schoenfeld, 2010).

This article will highlight those factors and give you the practical applications to apply it straight to your training.

1. Mechanical Tension

We’ve all been guilty at some point of putting more weight on the bar, even though our form wasn’t quite up to par. Although this may not be great long term, occasionally it may actually target 1 of the 3 mechanisms of muscle growth. Our egos are driving us to create more mechanical tension by lifting heavier weights.

Why does mechanical tension cause growth?

  • Signaling- Increased resistance disturbs the structure of skeletal muscle, causing signals to be sent to the muscle fibers and cells to repair themselves and become stronger by favoring synthesis instead of breakdown.
  • Structure– Normally dormant cells called satellite cells that sit on the outside of the muscle fibers become active when a sufficient mechanical stimulus is imposed on skeletal muscle. Once activated, satellite cells multiply and grow and ultimately fuse to existing cells or among themselves, providing the building blocks needed for repair and subsequent growth of new muscle tissue (Schoenfeld, 2010).

In the end, your muscles end up getting bigger and stronger.

Lifting heavier is not the only way to add mechanical tension though. You can create a ton of tension simply by squeezing a muscle as hard as possible and by focusing on the mind-muscle connection. Therefore, to really make your muscle growth you want to contract your muscles under the heaviest load possible, while keeping perfect form!

If mechanical tension was the only thing that caused muscle growth, then powerlifters would be as big as bodybuilders. However, there are other factors that come into play; here are mechanisms 2 & 3.

2. Muscle Damage



Imagine that you wake up two days after an insane leg workout. It seems like a regular day, but as you roll out of bed, you notice that your legs are very tight and sore. You go to the washroom and attempt to sit down, but the pain is so obvious that you have to use the countertop to help lower yourself to sit down.

That story illustrates a phenomenon called delayed onset muscle soreness (DOMS) that is largely associated with great amounts of muscle damage. It’s important to note muscle damage itself does not cause growth; however it is correlated to a range of cellular adaptations that can cause muscle growth, primarily through the roll of satellite cells’ activation and other transcription factors.

This type of training also causes large amounts of inflammation. Once damage is perceived by the body, anti-inflammatory cells rush to the site and start cleaning up and sending signals for growth and repair to the above mentioned satellite cells (Schoenfeld, 2010).

This does not mean that your workout was not effective if you can’t walk more than a few feet without tripping. By now you should know that a workout doesn’t always have to leave you sore to mean that your muscles are growing. There is one more ingredient in the muscle building recipe.

3. Metabolic Stress

Remember when you had a pump so big that your arms looked like they had basketballs popping out of them, or remember when you had a burning sensation feeling like somebody was stabbing you with scissors. Those are both what we call metabolic stress.

What makes metabolic stress work?

  • Hypoxia: lack of oxygen in the muscles due to reduced blood flow
  • Cell Swelling: pooling of the blood that causes the “pump”
  • Occlusion: restriction of blood flow by a large number of muscle contractions
  • Metabolic Buildup: accumulation of metabolites such as lactate, hydrogen ion, inorganic phosphate, Creatine, and others.

Practical Applications

Now you know the very basic science, what are the best ways to target these mechanisms?

Well, there are several key principles that you should apply for each mechanism.

If you’ve seen the 20 Week Scientific Mass Builder you may wonder why people are able to add such large amounts of muscle? Well, it is because all the training blocks and workouts are specifically designed to target ALL 3 mechanisms, rather than just 1 like most workout plans.

Quite simply, if you hit ALL 3 mechanisms you can triple your growth. Just imagine it like a paycheck; if you earn $1000 per month from 1 job your total income per month is $1000. However, if you earn $1000 from 3 different jobs, you are getting 300% greater income!

Here are some basics concepts to get you on the right track:

Mechanical Tension

  • Adding more weight to the bar,
  • Focusing on the mind muscle connection and peak contracts,
  • Squeezing the working muscle as hard as possible,
  • Long rest periods to completely recover and optimal performance / motor unit recruitment,
  • Lower frequency training that allows max recovery and performance from session to session,
  • Less dropsets / supersets which can cause fatigue and decrease performance,

Muscle Damage

  • Slower Eccentric Lifting tempos, for example 5 seconds to lower,
  • Weighted stretching / Intra-Set Stretching,
  • Heavy Eccentric / Negative Training at about 130% the concentric load,
  • Potentially using pauses in the middle of reps,
  • Lots of volume or sets per workout,
  • Frequent changes in exercise selection,

Metabolic Stress

  • Training to Failure,
  • Higher Rep Work,
  • Occlusion Training (BFR)
  • Compound supersets, tri-sets, and giant sets,
  • High volume load with shorter rest periods,
  • Short rest intervals,
  • My own Metabolic Resistance Training routines.

Important: If you want a done-for-you plan which utilizes all 3 of the muscle building mechanisms, advanced training variables and a lean muscle building meal plan check out 20 week mass!

As you are reading blog post and obviously serious about adding lean mass, I’m going to give you a ONE TIME 80% REDUCTION – I want you to have the most optimal training plan – there is nothing worse than people putting in the effort and getting slow results! (this expires in 24 hours, so take advantage now).


Putting it All Together

Current research suggests that maximum gains in muscle hypertrophy are achieved by training programs that produce significant metabolic stress and muscle damage while maintaining a moderate degree of muscle tension. The general recommendations would be:

  • Use all rep ranges from 1-5 (max tension), 6-12 (muscle damage and stress) to 15+ (metabolic stress).
  • Exercises should be varied in a multiplanar, multi-angled fashion to ensure maximal stimulation of all muscle fibers.
  • Multiple sets should be employed to build volume
  • At least some of the sets should be carried out to the point of concentric muscular failure, perhaps alternating microcycles of sets to failure with those not performed to failure to minimize the potential for overtraining.
  • Concentric repetitions should be performed at fast to moderate speeds (1-3 seconds) while eccentric repetitions should be performed at slightly slower speeds (2-4 seconds).
  • Training should be periodized so that the hypertrophy phase culminates in a brief period of higher-volume overreaching followed by a taper to allow for optimal supercompensation of muscle tissue. (Schoenfeld, 2010)



Schoenfeld, B. J. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. The Journal of Strength & Conditioning Research, 24(10), 2857-2872.

About the author


Rudy Mawer, MSc, CISSN

Rudy has a 1st class BSc in Exercise, Nutrition & Health and a Masters in Exercise & Nutrition Science from the University of Tampa. Rudy currently works as a Human Performance Researcher, Sports Nutritionist and Physique Coach. Over 7 years he has helped over 500 people around the world achieve long last physique transformations.

He now works closely with a variety of professional athletes and teams, including the NBA, USA Athletics, World Triathlon Gold Medalists, Hollywood Celebrities and IFBB Pro Bodybuilders. If you would like to get in contact or work with Rudy please contact him on social media.

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