What You Need To Know About Muscle Hypertrophy: Beginners Guide

The video above is a brief introduction into the two different types of muscular hypertrophy.

Muscle hypertrophy occurs when protein synthesis exceeds protein breakdown.  Your  body is constantly breaking down at the cellular level.  As we remain active, our body is constantly reconstructing itself to be more efficient at whatever activity we are doing.  As the muscles work harder and harder, microscopic tears are created when the muscle is pushed beyond what it’s capable of.  Hypertrophy occurs when we have consumed the proper amount of protein that allows the body to create enough amino acids to help muscles grow.  

How Do Muscles Grow?

When you place strain on a muscle through exercise or activity, damage occurs in the form of microscopic tears that the body now needs to repair.  This damage activates satellite cells that are located between the sarcolemma and basement membrane of the muscle fibers.  The body then repairs itself by adding amino acids to the myofilament, which results in muscle growth.  

Many people in the early stages of training quickly get excited about the fast increase in muscular strength, even though the size of the muscle hasn’t changed much.  When a beginner starts resistance training, there are many physiological changes that occur within the body that aren’t directly related to an increase in muscle size.  

At a neural level, our nervous system begins to adapt the physical changes placed on our body.  Exercise stimulates the sympathetic nervous system which will create an integrated adaptation within our myofibril tissue.  Think of it as building stronger links between our muscle cells, which in turn creates more refined muscle memory and strength adaptations.

As we continue to challenge the muscles beyond this initial phase, it’s important to understand the two different types of hypertrophy. 
    • Myofibrillar Hypertrophy – growth of muscle fibers responsible for contraction
    • Sarcoplasmic Hypertrophy – increased glycogen, creatine and ATP stores

Myofibrillar Hypertrophy

Myofibrillar hypertrophy occurs due to an overload stimulus.  When the body cannot lift heavier weight or generate maximum output for longer durations, this creates microscopic tears in the myofilaments.  In order for the body to protect itself, it needs to repair and grow in order to avoid being damaged again.  This type of hypertrophy results in performanced-based adaptations, such as increased strength and power.  

Sarcoplasmic Hypertrophy

Sarcoplasmic hypertrophy occurs when the muscle is under sustained tension with moderate loads.  Sarcoplasm is the fluid and energy sources that surround the myofibrils in the muscle.  Glycogen, creatine phosphate, water, and adenosine triphosphate (ATP) are a few elements that make up this layer.  As the body is put under sustained activity at moderate intensity, these elements are depleted and the body overcompensates by trying to create more room to store greater amounts.  This type of hypertrophy allows the muscle to perform more work for longer durations and increases the volume of the muscle to a greater extent than that of myofibrillar training.

Training To Meet Your Specific Goals

In the gym, the number of reps and the intensity at which they are performed are important.  As the load gets heavier, more muscle fibers are recruited in order lift the weight.  As time under tension increases and load decreases, the more the body relies on energy stores.

Myofibrillar Hypertrophy Training

Training around your 80% one rep max with at least 2 minutes of rest in between sets will produce the largest changes in myofibril density.  This can also be applied to aerobic activity as well.  Sprinting 100 meters recruits more muscle fibers than a 400 meter sprint and running a mile.  Lifting heavy or sprinting is the best way to produce more myofibril changes.  

    “Why not just lift at our 1 rep max?”

Training at maximum produces much more neuro-muscular adaptations over myofibrillar adaptations.  You also have to take into account the lasting affect on your bones, joints and ligaments when training that heavy.  Our goal for this type of training is to keep work time under 15 seconds.  If you are working longer than that, it’s not heavy enough or fast enough.  

Sarcoplasmic Hypertrophy Training

This type is training is known as “fatigue training”, and it’s focus is time under tension.  Generally rep ranges from 10-20 (or work time of about 30-60 seconds) achieves these results. Our goal is to burn through all of the stored energy in our muscles, so during our rest our bodies can learn to recruit and store more.  

Our immediate energy sources are ATP and creatine phosphate.  This correlates to our phosphagen system and is responsible for giving our muscles the most power.  After this, we enter the glycolytic state which is where the magic happens.  The breakdown of glycogen results in lactic acid build up (THE BURN), and that’s when you know that you are using up your muscles stored energy.  

Which One Is Better?

If you just want to see how much weight you can move or be the strongest person in your local gym, then go the heavy route.  Make sure you learn proper form and take care of your body when lifting heavy often.  

If you’re looking for that aesthetic appeal, then sarcoplasmic training is best suited for you.  Lifting at a controlled tempo, focusing on the muscles being worked, and maximizing time under tension are they keys to developing size. 

It’s easy to get wrapped up in one or the other.  However, variation is key to continual growth.   Both forms of training should be a part of your regimen in order to keep the body guessing.  Weekly, bi-weekly, or monthly cycles between the two will keep your body from adapting to one form of exercise and will have a much greater affect on muscle growth.