How genetics affect body shape and athletic performance

After 12 weeks of training, some participants doubled their strength and increased their muscles significantly, while others had little or no change. The worst-performing participants lost 2% of muscle mass and did not gain any strength at all, while the genetic lucky ones increased muscle mass by 59%, their one-rep max by 250%. And this is with absolutely identical loads.

Let's take a look at why the scores are so different and how genetics affect muscle growth.

How genetics affects muscle growth

Number of satellite cells

In his study, Dr. Robert Petrella suggested that the difference in performance under the same physical activity depends on the number and effectiveness of satellite cells - muscle tissue stem cells.

An earlier study found that participants with good muscle hypertrophy scores had more satellite cells and increased their numbers rapidly through exercise.

At the beginning of the experiment, the participants with the best indicators averaged 21 cells per 100 muscle fibers, and by the 16th week of training, the number of satellite cells increased to 30 per 100 fibers.

Participants whose muscles did not increase during the experiment had about 10 satellite cells per 100 muscle fibers. This amount did not change after training.

Gene expression

The dependence of athletic performance on genetics was confirmed by another study. As a result of the same training, out of 66 participants, 17 increased their muscle cross-sectional area by 58% (let's call them successful athletes), 32 participants by 28%, and 17 genetic losers by 0%.

The reasons for this scattering of results:

Increased synthesis of mechanical growth factor. Successful athletes - by 126%, genetic losers - by 0%.
Increased synthesis of myogenin. Successful athletes - by 65%, genetic losers - by 0%.
Increased synthesis of IGF-IEa genes from a variety of mechanical growth factor. Successful athletes - by 105%, genetic losers - by 44%.

Another study found that people with high expression of key hypertrophy genes adapt faster to strength training than normal people.

How genetics affects fat

In the past, genes that endow people with economical metabolism were an evolutionary advantage, because it helped to survive in times of famine. Today, when our lifestyles include sedentary work and excess calories, these same genes cause health problems and obesity.

A study on twins showed that people gain weight differently with the same diet. Twelve pairs of twins were over 1,000 calories per day for 84 days and were sedentary.

With the same diet, participants' results varied widely, ranging from 4 to 13 kilograms. People with the metabolic curse gained three times as much weight as the lucky ones, accumulated 100% excess calories, and increased visceral fat by 200%. The metabolic lucky ones did not have an increase in visceral fat.

Another study showed that heredity determines 42% of subcutaneous fat and 56% of visceral fat. This means that genetics directly affect where your body stores fat.

Another study suggested that changes in metabolic rate and energy expenditure for physical activity were 40% dependent on genetics. Another study found that body mass index is inherited by 40–70%.

In a 1999 study, genetics were shown to influence calorie intake. The same conclusion was reached by other scientists who studied the eating behavior of 836 participants. They found six genetic links that increase calorie and macronutrient intake, including the gene for adiponectin, a hormone that is involved in the regulation of glucose and the breakdown of fatty acids.

It turns out that not only dietary habits and stress levels affect excess weight. Some people are simply genetically more predisposed to overeat and accumulate fat.

How genetics affects strength

The most well-known physical performance-enhancing gene is ACTN3, known as alpha-actinin-3. This gene is being investigated to identify a predisposition to certain sports.

There are two types of alpha-actinin protein - ACTN2 and ACTN3. ACTN2 is found in all types of muscle fibers, and ACTN3 in type IIb - fast and large muscle fibers that are activated by short-term exertion and develop great strength. Therefore, ACTN3 is associated with powerful force production.

Approximately 18% of people worldwide have ACTN3 deficiency. Their bodies produce more ACTN2 to compensate for the lack. These people cannot make explosive movements as quickly as those who have an abundance of this protein. For example, among elite sprinters, there are no people with alpha-actinin-3 deficiency.

The angiotensin converting enzyme (ACE) gene is also involved in athletic performance. An increase in the ACE D allele is associated with strong athletes and sprinters, while an increase in the ACE I allele is more common in athletes with impressive endurance.

One study found that VNTR-1RN gene variants also affect physical development. This gene affects cytokines and enhances the inflammatory response and recovery processes after exercise.

Reichmann's study confirms these findings and links the cytokine interleukin-15 to increased muscle hypertrophy.

What is the bottom line

After all these studies, the opinion may be formed that a strong and beautiful body must be won in the genetic lottery. If you're unlucky, then there's nothing you can do about it. In fact, this is not the case.

First, everyone has genetics problems that need to be worked on. Some people are prone to accumulating fat, while others find it difficult to build muscle. Even among elite athletes, there are no people with perfect genetics, but they still work on shortcomings and achieve their goals.

Secondly, these studies did not take into account the characteristics of specific people and did not select training and nutrition programs for each of them. Yes, with the same program, people with good genetics will perform better, but if you choose the right load, even the worst genetics will not interfere with you.

Keep experimenting, choosing a program, changing your diet and exercising, then you will definitely achieve your goal, despite the genetics. Unlike genetic lucky ones, in your case it will be a real victory.