The Two Types Of Muscle Growth - Gains Everyday

The Two Types Of Muscle Growth

Becoming bigger, stronger and better-looking is one of the primary goals of many individuals that decide to take on weight training, and many of us also realize that our muscles naturally decrease after we are about 30 years old and want to weight train for longevity and quality of life. While training may seem pretty straightforward, there are actually many different types of adaptations that can occur. 

The increase in function of our body that we see when we weight train is a result of the adaptations that happen in the muscles! So let’s have a look at the two types of muscle growth and help you find out which style of training would therefore be suitable for your goals.

First, let’s explore the two different muscle fiber types.


Muscle Fiber Types 

Depending on the activity that you are doing throughout your training sessions, you can activate different types of muscle fibers. 

Generally we can distinguish between two types of muscle fibers:

  1. Fast-twitch muscle fibers
  2. Slow-twitch muscle fibers

At low levels of intensity (e.g., jogging or using a light dumbbell) you mostly activate the slow-twitch muscle fibers. Those fibers are great for low-intensity, long work and are not really great at producing force and power, so think of these as your ‘endurance muscle fibers’.

The more your training intensity grows however, the more fast-twitch muscle fibers you recruit, in order to endure the load. These fast-twitch muscle fibers were designed for high-intensity performance - Short, explosive bursts of power. Think of the fast-twitch muscle fibers as the fibers you want to engage when building muscle, because these fibers have the greatest potential for growth as well as power output. One example are chickens. They use their legs to stand on for long periods of time, but they use their wings for short bursts of flights, which is why the legs look skinny while the breast is voluminous.


But Is It Just The Fibers That Grow?

As we mentioned, training may seem pretty simple at first - You lift heavy weights consistently and, well… You grow bigger and stronger. However, you can get big and strong in different ways, because different styles of training lead to a different type of muscle growth.

 It is considered that there are two main types of muscle hypertrophy:

  1. Myofibrillar hypertrophy
  2. Sarcoplasmic hypertrophy

Myofibrillar hypertrophy is the increase in size of the muscle contractile units, called ‘myofibrils’ and commonly known as “muscle fibers”. These muscle fibers are the contractile elements of the trained muscle groups, which allow contraction and relaxation.

Sarcoplasmic hypertrophy, on the other hand, is the growth of the ‘sarcoplasm’, which is basically a jelly-like fluid that surrounds the muscle fibers. The sarcoplasm contains different non-contractile elements, which can grow in volume, depending on the type of training.

One way to support you muscle growth beside proper sleep and water intake is protein. We have carefully tested and selected the best protein powders on the market for you.


So, What Training Triggers Either?

It appears that the myofibrils are more closely related to maximum output of strength and explosiveness, while their sarcoplasm is engaged during intense, yet longer loads. In other words, myofibrillar hypertrophy is a result of a powerlifting approach to weight training, where you do 1-5 repetitions. Sarcoplasmic hypertrophy is a result of a bodybuilding approach to training, where you do 6-15+ repetitions with heavy weights. 

Now of course, these are not mutually exclusive! Though myofibrillar hypertrophy primarily results in increased maximum and relative strength, you have those adaptations with the other type of hypertrophy too, BUT… They are not as prominent.


How is muscle growth different between men and women?

There used to be a wide-spread misconception that weight training makes women look “bulky”, but it is now more widely known that women have to 1) eat an excessive amount of protein and other calories to bulk up, and 2) often take other supplements or even steroids to become very bulky. Naturally however, women can do the same training as men and have less volume than men. Men have higher levels of testosterone and other hormones that increase muscle growth. Both men and women should focus on building both muscle fiber types for peak performance, health and wellbeing. While short burst exercises can help you to become stronger and more powerful, endurance-based exercise also help you to become stronger and benefit heart health.


Take-Home Message

Our musculature appears to be flexible, having the chance to adapt for both short, very intense training bouts, or, medium intensity, prolonged bouts. This is possible because of the nervous system, our wonderful muscle fibers and their energy reserves! 

Whatever your goal may be, try to stimulate both types of muscle growth, as well as other functions like balance, agility, flexibility, and coordination. Also don’t forget to strengthen the small stabilizer muscles, to make your body more resilient. For example, check out our post on building strong knees.

Become a functional human being!

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