science of muscle growth

Conquer Thy Body: The Simple Science of Muscle Growth

 This is Part II (read Part I here) of a three-part series on understanding the fundamentals of a successful workout program. My goal is to help you avoid the common pitfalls in a world of false information. I will break down concepts using scientific reasoning and evidence, so you know exactly what you need to do to maximize your time and effort in the gym.

Build Muscle QuotesI’ve spent most of my life frustrated by my results in the gym.

Many years and dollars were wasted trying to find the “right” plan. I bought the latest and greatest supplements, and followed silly routines that promised I would look like Spartacus, Leonidas, or Wolverine.

My results were poor – only slight muscle development.

It wasn’t until I began to read about the science behind muscle growth that it all began to make sense. Once I started applying these concepts, I finally saw results.

The Basics of Muscle Growth 

Despite what we are told, there is no secret to muscle growth.

Scientific research has already been collected and measured. There is a straight forward set of doctrines that will guarantee us success IF followed.

Through investigating how the body responds to different activities, we can establish what works and what doesn’t.

I’m going to outline several concepts below – hypertrophy, muscle fibers, and progressive overload.

It’s important we understand the how of muscle-building, and these concepts will go a long way towards getting us there.


Muscle hypertrophy is a fancy phrase for muscle growth.

It consists of two factors:

  1. Sarcoplasm (fluid of the muscle)
  2. Myofibrillar (size of the muscle)

Muscle fiber diagramMyofibrillar hypertrophy is activated with low volume strength training, such as 3-6 reps (see the study here).

Sarcoplasmic hypertrophy is activated with higher volume endurance training, such as 8-12 reps.

Every time we lift weights, we are activating both sarcoplasmic and myofibrillar hypertrophy.

Depending on our routine, one will be more active than the other, but both are vital to muscle growth.

Research has shown that the ideal intensity to induce hypertrophy is a heavy, low volume workout routine.

A 2011 study concluded that:

Mechanical tension, muscle damage and metabolic stress are the three primary factors that promote hypertrophy from exercise. The mechanical tension is directly related to intensity of the exercise, which is the key to stimulating muscle growth. 

I have found this to be true through my own experiences, and I will elaborate in greater detail in part III of the series.

Muscle Fibers

Muscle fibers are the individual cells that make up skeletal muscle.

There are 3 types of muscle fibers:

  • Type I: Slow twitch
  • Type IIa: Moderate fast twitch, faster than Type I but slower than Type IIb
  • Type IIb: Fastest twitch

Type I fibers are slow twitch and are extremely resistance to fatigue. They contract slowly. Those with an abundance of slow twitch fibers would include athletes such as runners, cyclists, and swimmers, as those activities require intense aerobic activity.

Type II fibers are fast twitch and fatigue rapidly, but have a higher potential for muscle growth as opposed to Type I fibers. Type IIb fibers have the fastest rate of contraction, but also the fastest rate of fatigue.

Short, explosive forms of exercise engage the type II fibers; think compound movements such as deadlifts, squats, box jumps, clean and press, etc.

Type II fibers need to be progressively stressed to see muscle growth.


We each have inherent differences when it comes to the composition of our muscle fibers. Some of us have the ability to build more slow twitch fibers; others, fast twitch fibers.

For instance, marathon runners will have more Type I, slow twitch fibers. Sprinters would be the opposite, having more Type II, fast twitch fibers.

Each of us also have different “caps” when it comes to our genetic makeup.

An athletic monster like LeBron James, has elite Type II muscle fibers.

He is a freak of nature; his body immediately responds to training and he is able to build more muscle and athleticism than someone with an average genetic make-up.

Progressive Overload

Progressive overload facilitates hypertrophy and is the gradual increase of tension and stress on the body during each workout.

If we work out correctly, the stress placed on our muscles causes the muscle fibers to tear.

During the repair process, the muscle grows to adapt to the stress that was previously placed on it.

This is the basic premise of muscle growth.

Muscles adapt quickly to stress, so it’s imperative to continue to increase weight each time we lift. Without increased demand on the muscle, stagnation will occur.

Our goal is to do more every time we workout, using a variety of techniques:

  • More resistance (weight) – most common method
  • More reps (volume)
  • More frequent (multiple times a week)
  • More intensity (shorter rest times)

Progressive overload is the most important principle of weight training.

progressive overload

Here’s an example – last week, you did 3 sets of 7 reps, and on the last set, you were able to do 135 pounds.

To keep progressing your strength and muscle gains, you need to do more this week. Maybe you move up to 140 pounds or add another repetition or two. Either way, you are increasing the stress on your muscles.

You’ll hit a point where its not possible to do more. Don’t worry, this is normal. Otherwise, everyone would be lifting out-worldly amounts of weight.

The goal is to be consistent in both frequency and intensity.

We all have a genetic max, but chances are you are far from it. Continue to work hard each time in the gym and you are bound to see muscle growth.

P.S. It’s vital to track your progress for each workout.

You should log the exercise, reps, weight and rest periods. This way, you know you’re starting points for your next workout.

I like to write my numbers down, so I use this workout log. Workout Log

You can also use the note function on your smart phone or one of the many apps available on Android or Apple.

Bottom Line

What I have discussed here is just scratching the surface of the vast science of our bodies. It’s detailed, fascinating stuff – and I recommend everyone spend some time learning how our bodies work, especially when it comes to our muscles. It’s crucial to know the inner workings of our bodies to fully understand how to build muscle.

Knowing the basics of hypertrophy, muscle fibers, and progressive overload give you the knowledge you need to avoid the trial and error frustration that plagued me for years.

In Part III, I get into a few more research-backed techniques you can use in the gym to accelerate muscle growth.

Talk soon,

Screenshot 2015-11-21 at 12.56.17 PM



Any questions or observations of your own experiences in the gym?Comment below!

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