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The definitive (and practical) guide to muscle protein synthesis

Der definitive (und praxisorientierte) Ratgeber zur Muskelproteinsynthese

A short summary

  1. Muscle protein synthesis is the process your body uses to repair, strengthen and grow your muscle fibers.
  2. If you can increase your muscle protein synthesis and reduce your muscle breakdown, you will build muscle.
  3. The best way to increase your muscle protein synthesis is to do a lot of heavy strength training, eat enough calories and protein, and time your meals correctly.

Building muscle can seem like a confusing process. Some people say that you should use high reps in your workouts, while others say that you just need to focus on getting strong.

Some say you need to eat a high protein diet and others say it doesn't matter. Some say that you need to eat a meal immediately before and/or after training, while others say that eating enough calories throughout the day is enough.

How would you know who's right? Well, one way to navigate this morass of facts and opinions is to focus on exactly what you want to achieve.

And if your goal is to build muscle, then you need to understand all the strategies that target one thing: muscle protein synthesis.

You might be wondering what that is. Well, that's what you'll learn in this article. You'll learn what muscle protein synthesis is, why it's so important for building muscle, the six best ways to increase muscle protein synthesis and how to avoid things that reduce muscle protein synthesis.

Let's get started.

What is muscle protein synthesis?

To synthesize means to combine a number of things into a coherent whole. When it comes to muscle protein synthesis, this means creating new muscle tissue from amino acids. Amino acids are small molecules from which proteins are formed. The latter are continuously broken down and rebuilt in the body.

When the amino acids in the muscle tissue are broken down into their components, this process is also known as muscle protein breakdown. The processes of muscle protein breakdown and synthesis are active simultaneously at all times, but to varying degrees.

For example, if you are in a state of fasting, the rate of protein breakdown increases and if this exceeds the rate of muscle protein synthesis, this results in a loss of muscle mass. This condition is also known as negative protein balance.

If you eat protein, your rate of protein synthesis increases and if this exceeds the rate of protein breakdown, the result is an increase in muscle mass. This is also known as a positive protein balance.

In this way, your body moves back and forth between anabolic and catabolic states every day.

In normal health and nutritional circumstances, muscle protein synthesis is fairly stable and the cycle of cellular regeneration remains balanced.

Over the course of the day, this looks something like this:

Every increase in protein synthesis is followed by a corresponding increase in protein breakdown and the two more or less balance each other out. This is the reason why the average person neither builds nor loses muscle over a longer period of time. On a daily basis, there are no noticeable changes in lean body mass. (We do slowly lose lean body mass as we age if we don't actively do something about it, but I think you know where I'm going with this).

How protein synthesis affects muscle growth

But how are we supposed to build muscle if protein synthesis and protein breakdown balance each other out?

The answer is by increasing protein synthesis slightly more than protein breakdown over the longer term.

When the rate of protein synthesis exceeds the rate of protein breakdown over weeks and months, your muscles get bigger and stronger.

So what we call muscle growth is actually the result of the rate of protein synthesis exceeding the rate of protein breakdown over time. In other words, you build muscle when your body synthesizes more muscle protein than it loses. If your body synthesizes less protein than it loses, then you lose muscle in return.

And if your body synthesizes more or less the same amount of muscle protein as it loses, then you are neither building nor losing muscle.

This is why bodybuilders do everything they can to increase their protein synthesis rate and inhibit their protein breakdown.

This includes, among other things:

  • High protein and high carbohydrate diets
  • Progressive muscle overload in the gym
  • Making sure you are not in a state of calorie deficit
  • A suitable pre- and post-workout diet
  • Consuming protein before going to bed
  • Limiting cardio training
  • Supplements
  • And sometimes the use of steroids and other medications

The goal of all of this is simply to keep the rate of protein synthesis as far higher than the rate of protein breakdown for as many hours of the day as possible.

As you can see, there are many factors that cumulatively determine whether you build or lose muscle. Something else that is worth mentioning is the type of muscle protein synthesis we are targeting. All types of exercise including endurance sports such as cycling, swimming, skiing and hiking can increase the rate of muscle protein synthesis (1).

But why then are endurance athletes not muscle packed? Well, there are three reasons:

  1. Protein synthesis mainly takes place in the mitochondria - small power plants in the cells (2). The mitochondria multiply and become more efficient, which makes you better at endurance sports, but they don't increase muscle size (3). Strength training, on the other hand, increases protein synthesis in the actual muscle fibers, which makes them grow (4).
  2. There is also a large increase in protein breakdown during endurance sports, which cancels out the increase in protein synthesis (5).
  3. Most people who do endurance sports also limit their calorie intake, which increases the rate of muscle protein breakdown (6). So what can you do to keep your protein synthesis rate elevated long enough to build muscle? As you'll see in a moment, quite a lot.

6 ways to increase muscle protein synthesis

If you want to build muscle, you have two goals:

  1. An increase in muscle protein synthesis over as many hours as possible per day.
  2. To reduce muscle breakdown for as long as possible each day.

Let's tackle the first part of this equation first - increasing the rate of muscle protein synthesis.

Strength training and muscle protein synthesis

Since ancient times, we have known that lifting and putting down heavy things builds muscle. When we exercise our muscles, we damage cells in our muscle fibers, which signals the body to increase the rate of protein synthesis to repair this damage (7).

Here's what this looks like throughout the day

There are a few other things that happen in the muscle cells when we exercise that also stimulate muscle protein synthesis, but the most important factor is mechanical tension (8). This means moving heavier and heavier weights over time.

After a training session, there is a rapid and prolonged increase in muscle protein synthesis (9). This state lasts for up to 3 days in beginners and less than 24 hours in advanced exercisers. This difference is due to the fact that over time the body becomes better at recovering from training and therefore does not need to keep protein synthesis elevated for as long.

This becomes more important the closer you get to your genetic potential as your body becomes more resistant to the effects of strength training. It takes more and more sets to achieve the same increase in protein synthesis and this increase also falls back to baseline more quickly (10).

This is why you need to increase your training volume over time to keep your protein synthesis rate elevated and your muscle-building machinery running at full speed (11).

This is all well and good, but there is also a large increase in muscle protein breakdown that occurs when you train with weights.

In fact, the rate of muscle protein breakdown after a training session is significantly higher than the rate of muscle protein synthesis (12). After an hour or two in the gym, you are in a catabolic (muscle-degrading) state.

In other words, strength training increases both the rate of protein synthesis and the rate of protein breakdown.

The rate of muscle protein breakdown naturally decreases after some time, but strength training still has a net muscle building effect in the long run. However, as a steroid-free exerciser, you should do everything you can to reduce the muscle protein breakdown caused by training.

This is where nutrition comes into play, which we will look at next.

Calories and muscle protein synthesis

Yes, you need to eat enough protein, which is nothing new for people trying to build muscle, but many people don't realize that they also need to eat enough calories. Your body burns a certain amount of energy every day, which is measured in calories (one kcal is the amount of energy needed to heat 1 kilo of water by one degree). This amount of calories is called your total daily calorie consumption.

Your body gets the energy it needs to stay alive from the food you eat. The relationship between the amount of energy you consume and the amount of energy you expend is called energy balance and has a major impact on your body weight and muscle growth.

If you supply your body with less energy than it consumes, you generate a calorie deficit, which results in weight loss if you maintain it over a longer period of time.

However, such a calorie deficit also impairs your body's ability to synthesize muscle protein, which will slow or halt your muscle growth (13).

The physiology at play here is quite complex, but the short version is that your body switches into an energy-saving mode where certain bodily functions are prioritized over others when you restrict your calorie intake.

Building bigger muscles is not essential for survival and requires plenty of energy, which is why it is low on the list of priorities.

In addition, a calorie deficit can reduce levels of anabolic hormones and increase levels of catabolic hormones, which can cause a systemic shift from net protein synthesis to muscle breakdown (14, 15).

This is also the reason why it is commonly believed that you cannot build muscle and lose fat at the same time (which is not entirely accurate, as we shall see.

It is also the reason why women may miss periods if they restrict their calorie intake in order to lose fat (16). In a state of energy deficiency, the body can neglect the energy-hungry and non-essential process of menstruation. So what do you need to ensure in terms of your calorie intake if you want to build muscle as quickly as possible?

You need to make sure that you are not in a calorie deficit - regardless of your nutritional strategy.

Regardless of your nutritional strategy, if you are in a calorie deficit most of the time, you will struggle to keep your muscle protein synthesis rate high enough to build muscle.

If you want to maximize your muscle protein synthesis, then you need to make sure you're eating enough calories to maintain your weight. For most people, this means a calorie intake in the range of 30 to 34 kcal per kilogram of body weight.

In the second part of this article we will look at the influence of protein, protein timing, BCAAs and sleep on protein synthesis.




From Amistead Legge

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