Scientific Foundations of Strength & Hypertrophy Gains (Dr. Galpin)

This post delves into the intricate processes that enable our muscles to expand and strengthen. From the microscopic tears that stimulate muscle protein synthesis, to the crucial role of enhanced blood flow in nutrient delivery and waste removal, we uncover the science that underpins our body’s response to strength training.

Additionally, we examine the effects of neural efficiency and changes in connective tissue on muscle development.

Science Behind Muscle Growth: From Protein Synthesis to Enhanced Blood Flow

When we engage in strength training, we create small tears in our muscle fibers. These tears are then repaired by our body, and in the process, new muscle fibers are created.

This process is known as muscle protein synthesis, and it is the primary driver of muscle growth.

Another important change that occurs during hypertrophy is an increase in blood flow. As we engage in strength training, the demand for oxygen and nutrients increases.

Our body responds by increasing blood flow to the muscles, which helps to deliver the necessary oxygen and nutrients to the muscles. This increased blood flow also helps to remove waste products, such as lactic acid, from the muscles.

There may also be changes in neural innervation, which is the process by which our nerves communicate with our muscles. When we engage in strength training, our nerves may become more efficient at communicating with our muscles, which can help to improve muscle strength and endurance.

Another possible change that occurs during hypertrophy is changes in fascia, which is the connective tissue that surrounds our muscles. Fascia is important for maintaining muscle integrity, and it may also play a role in muscle growth and repair.

It’s important to note that these changes are not mutually exclusive, and may occur simultaneously. For example, when we engage in strength training, we create small tears in our muscle fibers, which triggers muscle protein synthesis. At the same time, blood flow increases, and our nerves may become more efficient at communicating with our muscles.

Dr. Galpin also added that these adaptations are similar when we talk about hypertrophy and mode of training is close enough.

Nerves are not smart enough to differentiate between a set of five reps or a set of eight repetitions. But primary difference with hypertrophy is a couple of things.

So if you think about the muscle microstructure, we have a whole series of videos on YouTube if you want to see the visuals behind this.

The muscle protein synthesis, generally what we’re talking about there is contractile units. And so when we say contractile units, we’re talking about the myosin and actin.

And so what we’re really trying to do is say, okay, there’s some amount of protein turnover where we’re coming in and we’re trying to add more proteins to the equation.

Dr. Galpin also emphasize that the muscle protein synthesis can come from stretching of the cell wall, which is what happens with exercise. But it can also come from simple things like an amino acid infusion.

This is just eating protein. This is why protein ingestion alone is anabolic. It will help you grow muscle independent of even moving.

It’s also interesting to note that if you do the exact same study again and you just did strength training, you would also see an improvement in protein synthesis.

But those factors are independent and the mechanisms are independent such that if you do them both together, they stack on top of each other, which is really wonderful.

And if you were to add carbohydrate into that mix, now you’re actually adding fuel for the entire muscle protein synthesis process and now you’re going to see even additive

Strength vs. Endurance Training: Divergent Paths to Protein Synthesis

Dr. Huberman asked if the same benefits of strength training, such as an increase in protein synthesis, can be achieved through endurance-type exercise, such as a 45-minute jog.

Dr. Galpin stated that this is not the case. In fact, endurance training has the opposite effect, and it is difficult to measure protein breakdown.

The reason for this is that there is a unique molecular cascade that occurs during strength training. This cascade is activated by different signals, such as glucose uptake, protein intake, or a physical stretch.

These signals activate a series of cascading signaling proteins, which then activate a whole set of gene cascades that lead to protein synthesis.

This process is fundamentally the same, regardless of the type of insult, but there are different pathways.

The pathway from strength training or protein ingestion will activate an anabolic signaling cascade that leads to protein synthesis, while the pathway from endurance training will activate a different cascade, such as AMPK and energy signaling. However, there is a crossover point where endurance training can also activate the mTOR and AKT cascade, leading to protein synthesis.

Dr. Galpin also highlighted that the process of protein synthesis is not as simple as it seems. It involves a combination of amino acids that form peptides and polypeptides, which ultimately form proteins.

The process is the same regardless of the type of protein being synthesized, whether it be a red blood cell, hair follicle, or skeletal muscle.

Dual Paths of Muscle Hypertrophy: Contractile and Sarcoplasmic

Skeletal muscle hypertrophy is generally thought of as an increase in contractile protein. This means that the myosin and actin fibers in the muscle get thicker, which can affect the lattice spacing within the muscle cell.

In response, the body increases the diameter of the entire cell to maintain this spacing. This is similar to two people sitting in a room and one person doubling in size, causing the other person to also double in size to maintain their personal space.

However, there is another type of muscle hypertrophy known as sarcoplasmic hypertrophy. This refers to an increase in muscle size that has no functional benefit, as there is no increase in contractile units.

This concept was often considered bro science in the past, but recent studies by Mike Roberts at Auburn have shown that sarcoplasmic hypertrophy is likely happening.

This type of hypertrophy is caused by an increase in fluid within the muscle fiber, which allows for the diameter to be larger without any increase in force production.

Dr. Huberman also mentions the concept of neuroplasticity in the nervous system, which is the ability for the nervous system to change in response to learning, experience, and damage.

He compares this to the different types of muscle hypertrophy, stating that there are many paths to what we think of as hypertrophy and strength increase.

Certain forms of exercise and different sets and repetition schemes tap into different mechanisms, which is why strength increases are often associated with hypertrophy changes and vice versa.

Muscle Memory: The Role of Myonucleation in Hypertrophy

Skeletal muscle is unique in that it is large in diameter and multinucleated, meaning that it has thousands of nuclei rather than just one. This gives muscle fibers a great deal of plasticity and allows them to up-regulate, down-regulate, and repair more easily.

For years, scientists believed that the amount of hypertrophy a muscle could experience was limited by the number of nuclei it had. However, recent research has shown that the number of nuclei in a muscle fiber can be increased through the process of myonucleation.

This process involves satellite cells, which are dormant cells that can be found on the periphery of muscle fibers. When these satellite cells are activated, they turn into myonuclei and can increase the diameter of the muscle fiber.

This discovery has led to a new understanding of the concept of muscle “memory,” which is the ability of muscle fibers to regain size and strength more quickly after a period of detraining.

This phenomenon is thought to be related to the number of satellite cells available to turn into myonuclei, as well as other factors such as the ability of muscle fibers to up-regulate and down-regulate in response to changes in muscle use.

However, it is important to note that the concept of muscle memory is not limited to muscle physiology.

It is also used to describe the ability of the nervous system to remember certain movements, such as riding a bicycle or playing an instrument. This is a separate phenomenon, but one that is closely related to the muscle physiology.

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Articles Mentioned

  • Sarcoplasmic Hypertrophy in Skeletal Muscle: A Scientific “Unicorn” or Resistance Training Adaptation?: https://bit.ly/3j4sXxq
  • Towards an improved understanding of proximity-to-failure in resistance training and its influence on skeletal muscle hypertrophy, neuromuscular fatigue, muscle damage, and perceived discomfort: A scoping review: https://bit.ly/3Dd9MIy

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