Muscle growth training in the gym

Muscle Growth

Muscle Growth


Building muscle is a integral part of becoming fitter, it helps with strength and raises your metabolism. Starting to build a better body for your future means the need for more muscle. I will start with a basic explanation of how muscle growth occurs and then get on to the technical stuff.

For muscle breakdown and growth to occur you must force your muscles to adapt by creating stress that is different than the previous threshold your body has already adapted to. This can be done by lifting heavier, constantly changing your exercises so that you can damage more total muscle fibers and pushing your muscles to fatigue while getting a “pump.” After the workout is done, the most important part begins which is adequate rest and providing ample fuel to your muscles so they can regenerate and grow.

Muscle growth takes time and is relatively slow for the majority of people. People will generally not see visible growth for several weeks or months due to the majority of the initial changes being due to the ability of your nervous system to activate your muscles.

In addition to that, different people have different genetics, which range from hormonal output, muscle fiber type and number, along with satellite cell activation, that can all limit muscle growth. To ensure you’re doing your best to grow muscle, muscle protein synthesis must exceed muscle protein breakdown. This requires that you consume an adequate source of protein (especially essential amino acids) and carbohydrates to help facilitate the cellular process of rebuilding broken down muscle tissue.


Once you have completed a workout, your body repairs or replaces damaged muscle fibers through a cellular process where it fuses muscle fibers together to form new muscle protein strands or myofibrils. These now repaired myofibrils increase in thickness and in number to create muscle hypertrophy (growth). Muscle hypertrophy occurs when the rate of muscle protein synthesis is greater than the rate of muscle protein breakdown. This however, does not happen while you actually lift the weights. Instead, it occurs while you are at rest.

So how do you  add muscle to your muscle cells ?

This is where Satellite cells come in, acting like stem cells for your muscles. When activated, they help to add more nuclie to the muscle cells and therefore contribute directly to the growth of myofibrils (muscle cells). Activating these satellite cells may be the difference between what allows certain people to grow massive muscles and what makes other people less prone to building muscle. It seems the more you can activate these satellite cells, the more you’ll be able to grow. So how do you activate these satellite cells to increase muscle growth ?

Mechanisms for muscle growth

The biggest factor in muscle growth is your  ability to continually put more stress on the muscles. This stress is a major component involved in the growth of a muscle and disrupts homeostasis in your body. The stress and subsequent disruption in homeostasis causes three main mechanisms that spur on muscle growth.

Muscle Tension
In order to promote muscle growth, you have to apply a load or stress greater than what your body or muscles have previously adapted too

So how do you do this ?

The answer is to lift progressively heavier weights. This additional tension on the muscle helps to cause changes in the chemistry of the muscle, allowing for growth factors that include mTOR activation (MTOR is a serine/threonine protein kinase that regulates cell growth, cell proliferation, cell motility, cell survival, protein synthesis, and transcription) and satellite cell activation.

Muscular tension also most dramatically effects the connection of the motor units with the muscle cells. Two other factors help to explain why some people can be stronger, but not as big as other people.

Muscle Damage
Feeling sore after a workout means you have experienced  localized muscle damage. This local damage causes a release of inflammatory molecules and immune system cells that activate satellite cells to get to work. This doesn’t mean that you have to feel sore in order for this to happen, but instead that the damage from the workout has to be present in your muscle cells.

Metabolic Stress
When you feel the burn in the gym or had the “pump” , then you’ve felt the effects of metabolic stress. Scientists used to question bodybuilders when they said the “pump” caused their muscles to become larger. After investigation, it seems as though they were onto something.

Metabolic stress causes cell swelling around the muscle, which helps to contribute to muscle growth without necessarily increasing the size of the muscle cells. This is from the addition of muscle glycogen, which helps to swell the muscle along with connective tissue growth. This type of growth is called sarcoplasmic hypertrophy and is one of the ways that people can get the appearance of larger muscles without increases in strength.

Hormones and muscle growth

Hormones are another component responsible for muscle growth and repair because of their role in regulating satellite cell activity. Insulin Growth Factor, in particular Mecho-Growth Factor and testosterone are the two most important mechanisms that promote muscle growth.

Testosterone is the main hormone that most people think about in the gym environment, testosterone increases protein synthesis, inhibits protein breakdown, activates satellite cells, and stimulates other anabolic hormones. Although most testosterone is bound in the body and therefore not available to use, strength training seems to help not only release more testosterone, but also make the receptors of your muscle cells more sensitive to your free testosterone. Testosterone can also stimulate growth hormone responses by increasing the presence of neurotransmitters at the damaged fiber site, which can help to activate tissue growth.

The Insuliin Growth Factor regulates the amount of muscle mass growth by enhancing protein synthesis, facilitating glucose uptake, repartitioning the uptake of amino acids (what protein is made of) into skeletal muscles and once again, activates satellite cells to increase muscle growth.

Muscle Growth and rest 

When you do not provide your body with adequate rest or nutrition, it actually reverses the anabolic process and puts your body into a catabolic or destructive state. The response of muscle protein metabolism to a resistance exercise bout lasts for 24-48 hours. The interaction between protein metabolism and any meals consumed in this period will determine the impact of the diet on muscle hypertrophy.