Hypertrophy and muscle growth

Geschatte leestijd: 15 minuten In this article, I will discuss the various processes of muscle growth and hypertrophy. How and under what circumstances does a muscle grow? Do you always have to damage the muscle for growth, and should you feel muscle pain as evidence of this damage? What is muscle pain exactly and how is it exactly caused? What role do nutrition, supplements, and anabolic steroids play in these processes? What is the importance of intensity, volume, and variation of training forms? What is the difference between hypertrophy and hyperplasia? For an explanation of how muscles work, what they are for, how they work, and how muscles are built up, I refer to the article: the functioning of muscles. Most people initially “just” train by following the example of others, but some eventually reach the point where they want to know exactly what the effect of their effort is and how this effect comes about. This article is for them.

Hypertrophy and muscle damage

As I wrote in the introduction, most people who train for muscle growth know that this can be achieved by consciously damaging their muscles through training. The body’s recovering, overcompensating response ensures that the damage is repaired and the restored part becomes stronger and larger to be able to handle the load in the future. This form of muscle growth is called hypertrophy. As explained in the previous section, the muscle works by allowing myosin and actin filaments in the sarcomeres to pull towards each other (contraction) and then release. However, when the load is too heavy for the contraction, the connection between myosin and actin can be torn apart (especially in the eccentric phase when the muscle is lengthening), causing what is often referred to as microtrauma, small tears. With these tears, other important parts of the muscle cell/fiber are also damaged. In this respect, overload is the magic word. Overload is simply any load that your muscle cannot handle at that moment, so it does not necessarily have to be very heavy. For example, with drop sets, you start with a heavy weight and when you can no longer do any more repetitions, you immediately continue with a lighter weight. Eventually, you can be working with “baby weights” and still cause muscle damage because your muscles simply no longer have enough energy to sustain the contraction. The same applies if you do many repetitions with a light weight and can’t do the last repetitions. But I’m already going too much into training forms, which will be extensively covered later. Immediately after the damage occurs, there is an inflammatory response that ultimately leads to the repair of the muscle fibers, making them stronger and larger. This inflammatory response is a series of activities involving growth factors, signaling molecules, various white blood cells, chemicals, fluids, and satellite cells.

Neutrophils

Neutrophil granulocytes, briefly neutrophils, are the first cells to arrive at the damaged muscle cell. Neutrophils are one of the five main types of leukocytes (white blood cells). They make up about 60% of the total amount of white blood cells. Their main function is to ingest and digest certain substances, especially harmful bacteria. In this way, they form the first immune response, the first step of the immune system in response to inflammation. Upon arrival at the muscle cell, they release toxic substances and enzymes that further break down the damaged tissue.

Macrophages

After the neutrophils, macrophages (or “histiocytes”) follow. Macrophage comes from the Greek makros=large and phagein=to eat and stands for “big eater.” “A macrophage is a large mononuclear cell capable of transforming remnants of dead or damaged body cells into intercellular material, foreign cells” (source: wiki). The neutrophils and macrophages literally eat up the tissue broken down by the neutrophils and remove it from the damaged location. This makes room for and prepares for the repair. In this respect, repairing the muscle is the same as replacing a broken window: You can only repair it when the old shards are removed.

Swelling after muscle damage

The swelling that can occur after muscle damage is caused by large amounts of fluid filling the muscle cell and the surrounding area. This increase in fluid stretches the cell membrane (shell of the cell). This signals to increase the size and strength of the cell to prevent it from bursting. In muscle, this is achieved by increasing protein synthesis (building muscle proteins) and reducing protein breakdown. This already explains part of the growth, but also part of the success of creatine as a supplement. Besides helping with ATP production as discussed in part I, creatine also attracts extra fluid to the muscle cell.

Satellite cells and cell nuclei

In addition to clearing up, macrophages have another very important function. They release chemicals that activate and grow so-called satellite cells. Satellite cells are specialized muscle stem cells that contain almost no plasma. These are inactive until they divide in case of damage and one of the new cells moves towards the damaged area and donates its cell nucleus to the muscle cell by fusing with it, thereby giving it more cell nuclei. The cell nucleus controls all the actions of the cell. The more cell nuclei, the more efficient the cell (and thus more power to generate), but also the more plasma the cell can retain (which determines, among other things, the maximum volume of the cell) and the more muscle proteins can be built up. Studies have shown that people who do a lot of resistance training have more cell nuclei than untrained people. In the article on muscle memory, I also described this principle as an explanation for the fact that people who have previously trained a lot quickly regain muscle mass after a period of rest. During the rest, the muscle cells may have become smaller in size, but the number of cell nuclei does not decrease. The muscle then retains its previously achieved potential for additional growth. Satellite cells can also, instead of fusing with an existing muscle fiber, form new myoblasts themselves. A myoblast is a precursor of a myocyte, a muscle cell/fiber, which can then develop into a new muscle fiber.

Is muscle pain necessary for muscle growth?

If you’ve never heard the expression “No pain, no gain,” you haven’t been to the gym often enough. This saying implies that pain is an indication of a good workout and thus muscle growth. Before I delve into the background and accuracy of this expression, I first want to make an important distinction between “good pain” and “bad pain.”

Bad pain

Bad pain is pain caused by, for example, joints, attachments, and sudden, sharp pain. Joint pain can be caused by incorrect execution of an exercise or insufficient warm-up. A good warm-up produces synovial fluid that serves as lubrication for the joints. Pain in the attachments can also have various reasons. Again, a warm-up is important here because the circulation in the attachments, which provides nutrients and removes waste products, is worse than in the muscle itself. A warm-up increases circulation before the attachment is loaded. If you want to know more about this, read the article about tendon injuries. Sharp pain can indicate a tear or strain in the muscle or the attachment. If you persistently train with these types of bad pain, you only worsen the symptoms, making it increasingly difficult to train heavily and thus grow less or not at all in the conscious area. So Bad pain is no gain! Also, read the article: Tendon injuries, cause, treatment and recovery

Good pain

Good pain can be experienced during and after training. The good pain during training is mainly caused by the buildup of lactic acid. In part I of this article, I discussed the different energy systems: 1. ATP-CP system / phosphagen system 2. The Anaerobic system / lactic acid system 3. The Aerobic system In the Anaerobic lactic energy system, active from about 20 seconds of heavy intensity, carbohydrates are incompletely burned, leading to the formation of lactic acid. When more lactic acid enters the muscle than is removed, it accumulates. When the lactic acid then comes into contact with nerve pain points, this leads to a pain stimulus. Lactic acid is an indication of great effort for more than a second or 20, but does not necessarily mean that (good) muscle damage has been caused. The good pain after training is called Delayed Onset Muscle Soreness (DOMS). There has been a lot of research into the cause of DOMS with various results. Multiple culprits have been identified, such as: Lactic acid (just like the good pain during training), muscle damage and resulting inflammatory response (the good damage that leads to growth), damage to attachments and muscle spasms. Which of these ultimately makes the biggest contribution is not clear. It is likely to be a combination of several causes.

Muscle pain = muscle growth?

So this depends on the cause of the muscle pain. This can indeed be caused by microtrauma, the small tears that lead to hypertrophy and muscle growth, or by the inflammation that has arisen. However, it can also be caused by lactic acid, and that lactic acid does not necessarily have to result from training that has led to good damage. Finally, it can also mean damage to an attachment. With some experience, you will quickly know whether a pain comes from the attachment or the muscle itself.

Muscle protein synthesis and protein synthesis

If microtrauma leads to muscle pain, do you always have to have muscle pain to grow? The answer is: Fortunately not. Experienced strength athletes increasingly have to make an effort to experience muscle pain. This is often simply called “habituation,” but we often do not know why this happens. If muscle damage occurs due to training, this does not occur everywhere in the muscle, but only in the fibers that are least resistant to the load. These fibers are not generally the weak links in the muscle, but are at that moment during the exercise or type of execution. J You can read above what steps the muscle takes to strengthen this link as protection against subsequent damage. Research has shown that once damaged and repaired, it is almost impossible to damage a muscle fiber again for several months. This is called the “Repeated bout effect”:

“subsequent bouts of the same exercise, repeated within several days to several months, do not produce as much damage as the first bout” McHugh et al. – Journal of athletic training

In the Netherlands, we use the more general term “law of diminished returns” for this.

Law of diminishing returns

The same strength athletes who experience less and less muscle pain often also see that they still grow despite this, although less than when they started strength training. These results are achieved through the second form of muscle growth:

Muscle protein synthesis

Muscles can also grow by increasing the amount of protein they contain. Muscle cells consist largely of protein. The more protein in the muscle cell (muscle proteins), the larger the muscle cell, the larger the muscle. The muscle cell can make protein by making chains of available amino acids. This is called muscle protein synthesis. Muscle protein synthesis occurs in and around the nuclei of a muscle cell. The muscle cell nuclei contain the genes and DNA that have the blueprint (encode) for (the sequence of amino acids in) all proteins in a muscle. Simply put: When the muscle cell receives the signal to build more protein (for example, through training), this blueprint is copied by the macromolecule messengerRNA (mRNA). mRNA first copies the sequence of amino acids (transcription) and then leaves the cell nucleus, after which the amino acids are brought together in the long chain of the copied protein (translation). Various processes and substances are involved in giving the signal for copying and making protein. These processes and the role of the various substances are very complex. I will therefore not go into all of them, but rather link to wiki for those who really want to delve into the genes.

• mTOR: Mammalian target of rapamycin: Plays a role in regulating growth factors, insulin, and amino acids
• Cytokines: Signaling molecules
• MAPK: Mitogen-activated protein (MAP) kinases: Plays a role in the cell’s response to various stress factors (e.g., heat, inflammation)
• Testosterone: The anabolic-androgenic steroid hormone testosterone works anabolically, which means it signals to use nutrients to build muscle proteins (instead of breaking down protein to provide energy as the catabolic stress hormone cortisol does).
• Insulin: The peptide hormone insulin mainly ensures constant glucose levels in the blood, but also has anabolic properties.
• IGF-1 and HGH: Insulin-like growth factor, a protein encoded by the gene IGF1, and Human Growth Hormone (Growth Hormone). IGF-1 is a metabolite (derivative of) HGH and is structurally similar to insulin, hence the name. IGF-1 is a growth factor that not only grows muscles but basically every cell. Especially organs grow due to IGF-1, which is why the use of IGF-1 as doping can cause nasty side effects. Think of the “Roid guts,” the protruding bellies of bodybuilders. They are bone dry on stage, clearly visible in their abdominal muscles, but still have a large waist. This is because the organs in the abdominal cavity also grow. HGH, growth hormone, produces various growth factors, including IGF-1.

Testosterone, insulin, IGF-1, and HGH are all used as doping with various risks and results. However, insulin is so risky and relatively ineffective that even most hardcore users of steroids do not use it (rightly). Growth hormone is more often used by the pros and relatively little by amateurs because the synthetic product is very expensive. Human growth hormone obtained from the pituitary gland of deceased individuals as used in the medical science in the past is sometimes still used as an alternative despite the risk of contamination with diseases such as Creutzfeldt-Jakob.

Amino acids and muscle growth

Many of the substances mentioned in the protein synthesis process can be compared to the role of a construction worker in building a house. An army of construction workers can, in the style of Extreme Home Makeover, build a castle in a day. However, this can only happen if there are enough building blocks. If not, all the manpower is useless. No matter how many of these signaling substances the body has, it is important that there are enough amino acids to build protein. In addition, there must be enough energy in the form of mainly carbohydrates, but also fats and proteins to prevent the body from breaking down already built protein to provide you with the necessary energy. Since your brain uses a large part of the energy, you can imagine that your body finds this more important than building muscle mass. Proteins in food are first broken down into amino acids. These can be used as energy, but can also be rebuilt into muscle proteins in the cell.

Hypertrophy or muscle protein synthesis

In hypertrophy, muscle protein synthesis is always involved. The same activity that led to damage also leads to muscle protein synthesis. Conversely, this is not always the case. As read, hypertrophy and muscle growth are harder to achieve because the muscle needs a greater load than it can handle. Due to the law of diminishing returns, or the repeated bout effect, this becomes increasingly difficult to achieve. However, hypertrophy is preferred. In the article on muscle memory, I explained that the extra cell nuclei provided by satellite cells apparently remain in the muscle cell for years, possibly forever. The size may decrease, but the number of nuclei remains the same. When people say “Bodybuilding is a thankless sport,” they say that because you can feel that if you stop training for a while and your muscle mass is lost, you basically have to start over. This applies to muscle growth due to protein synthesis because muscle proteins are broken down again when training is stopped and there is no longer a need for such size and/or when the diet is insufficient to keep the muscle cell large. However, hypertrophy-induced muscle growth means that when you start training again, the result follows much faster than the first time because the cell nuclei are already present. Therefore, focus as much as possible on hypertrophy, as muscle protein synthesis also occurs, and you benefit from it longer.

Hypertrophy vs. hyperplasia

In the case of hypertrophy, muscles grow in size because the muscle fibers grow in size. In the case of muscle hyperplasia, muscles grow because the number of muscle fibers increases in number through cell division. Conventional knowledge suggests that hyperplasia of skeletal muscles after birth is not possible. However, there have been several studies by researchers who challenge this and indicate that they have observed hyperplasia in the muscles of animals or indirectly demonstrated it based on human studies. In addition, there is the persistent assertion that growth hormone could cause hyperplasia. Hyperplasia of skeletal muscles in humans (after birth) has not been unequivocally established. Measurement methods to count the number of fibers are controversial and, for example, can in some cases be caused by satellite cells forming new fibers. I will address both hyperplasia and growth hormones separately in a later article.

More muscle growth through variation

As I said, it often becomes increasingly difficult to overload your muscles. The weak links (muscle fibers/cells) have become stronger and protect themselves against new overloads. The reason why so many people encounter this law of diminishing returns is mainly because humans are often creatures of habit. Indeed, you must be to have the discipline to watch your diet all day and go training multiple times a week, even when you don’t feel like it. In the article on motivation, I explained that training and nutrition become much easier when it becomes a habit. You just do what you’re used to. People who train fanatically are often the biggest creatures of habit. A good example is the DVD “The cost of redemption” by Ronnie Coleman, where every meal is the same and his statements are so repetitive that you would think the record got stuck, if it weren’t for the fact that nowadays most people don’t know what a record is anymore. The biggest pitfall is that while habit ensures that you train and eat properly when you should, it often means that the training itself becomes a fixed pattern of exercises. Many try to vary by simply doing the same exercise with increasingly more weight. I know several guys at the gym where, depending on the day, I know exactly which exercises they are going to do. They then do their usual routine, as always. However, you then target the same muscle fibers that have already been repaired repeatedly and hardly respond anymore, even with heavier weights. Unfortunately, this will not lead to muscle growth. One of the most important things for training (besides correct execution, perhaps the most important) is therefore variation in training.

Tips for variation in training for more muscle growth

There are many ways to introduce variation into your training. Below you can find some tips for varying your training.

• Change your training schedule every 4 to 6 weeks or use a fitness schedule that already includes this variation.
• Instead of changing every few weeks, you can also do each training for a muscle group differently. The advantage is that every training is new in the beginning and your body responds to it. The disadvantages are that you will soon have done all the variation you can think of and your body can quickly get used to all that variation. Moreover, it is difficult to measure strength progression if you do a different exercise every time, although this can always be stimulating. If you change your schedule every few weeks as in the first tip, you can measure progression and it has always been a few weeks or longer since you did a variation. Your body can never get used to it.
• Train negatively or eccentrically. In the article on eccentric training, I explain that negative repetitions according to many studies result in more muscle damage and therefore hypertrophy than “normal” concentric training. Eccentric training can be more difficult in practice if you don’t have a partner (then there are immediately fewer exercises you can do). Moreover, your body also gets used to it, so it doesn’t make sense to only train eccentrically from now on.
• More repetitions, less weight. Bodybuilders usually train with a lot of weight and do relatively few repetitions, usually somewhere between 4 and 12 repetitions per set. Try doing, for example, 15 to 20 repetitions for a while. Due to the longer time needed for one set, you stay longer in the anaerobic lactic energy system (20 seconds to 2 minutes) and produce more lactic acid. Your body is not yet used to this, becomes overloaded more quickly, and will therefore respond better.
• Forced repetitions can be used during your regular training to ensure overloading. Some examples.
• Actually, I’ve already given an example of this with eccentric training. Forced repetitions mean going beyond what you can actually do. With eccentric, you do this by taking more weight than you can lift and then slowing it down on the way down.
• Taking a rest for a few seconds and then continuing.
• Having someone help with a few extra repetitions that you couldn’t do alone.
• Dropsets. When you can’t do any more repetitions, immediately choose a lighter weight and continue. You can do this several times until you end up groaning with baby weights in your arms. Some lower the weight only two or three times, others do this until they reach the lightest weight.
• Supersets and giant sets. With a superset, you do two or more exercises for the same muscle group in a row without rest. With a giant set, these are four exercises. In practice, however, the names are often confused.
• Cheating and half reps. Doing half repetitions is a form of cheating. You do the exercise in an easier way than usual. You should only use this as forced repetition by starting with it when you can no longer do normal repetitions. Think of bench presses. You first lower the bar a number of times to the chest. When you feel you can no longer do this, do a few more repetitions where you lower the bar halfway. Another form of cheating is by using your body or momentum to do a few more repetitions. You often see monkeys swinging who immediately start with too heavy weight and use their whole body to lift the weight, for example, with bicep curls or side laterals for shoulders. Start with good execution where you isolate as much as possible the muscles you are training (just stand still with those curls). When you can’t do that anymore, you can swing to force a few more repetitions. However, be careful with the attachments and keep it controlled! In the example of the biceps curls, don’t let the arm drop and jerk it up with a straight arm, which would overload the distal attachment.

The role of nutrition in muscle growth

On this site, there are several pages dedicated to nutrition that extensively discuss the role of various nutrients. Here I will only briefly discuss the nutrients that have been discussed and place them in the context of the processes discussed in these two parts.

• Carbohydrates and fats: In part I, I described the energy supply to muscles. Glycogen plays a major role as fuel. Carbohydrates are the main supplier of glycogen. Their main role in the muscle growth process is to provide energy to ensure that you have the energy to train in addition to your daily activity and to prevent muscle breakdown to provide energy when there is not enough available. Fats play a similar role as an energy supplier, but are like a reserve tank filled with diesel. Fats provide more energy per gram than carbohydrates (respectively 9 kcal and 4 kcal), but do so less quickly. It takes more oxygen to burnfat and because this process is slower, fat provides less high energy peaks. However, carbohydrates are present in very small stocks in the liver and muscles in the form of glycogen. The maximum glycogen stock is very limited. There is about 200-400 grams in the muscles. In the liver, there is a reserve of about 75 to 100 grams and finally, there is glucose in the blood. Depending on the intensity of activity, you can only rely on glycogen for a few hours to a day. However, fat can be stored in tens of kilograms. It is of course not what you want and certainly not healthy, but in theory, you can carry 200 kilograms of fat and survive on this for two years in terms of energy.
• Protein: Muscles can only make muscle protein from amino acids when those amino acids are present. You get these by eating/drink protein-rich foods so that the protein in the body is broken down into amino acids. These amino acids can then be built up into specific muscle protein again. Protein can also serve as an energy source when there are not enough carbohydrates and fats available. To prevent muscle breakdown, it is therefore important to have enough carbohydrates, fats, and protein.
• Creatine: In part I, I described the role of ATP as the main supplier of energy for muscles. Creatine essentially ensures that ATP can be produced faster and more. Carbohydrates and fats are relatively easy to get in sufficient quantities. With protein, it is already more difficult, but still possible to get from food. However, creatine occurs in such small quantities that, despite the relatively small required amount, it is almost impossible to get enough from food. Creatine is therefore one of the most popular supplements in bodybuilding and fitness.
• Water: Necessary for countless processes, but in muscles, among others, for the supply and removal of nutrients and waste products. Also, filling the muscle cell with fluid through training increases its volume, causing it to grow and become stronger to accommodate the new volume.
• Calcium and magnesium: Important for contracting and relaxing muscles.

In the third and final part, I will discuss different muscle fibers and the body types ectomorph, mesomorph, and endomorph.