Amino acids and sport


Amino acids are the building blocks of protein. There are around 250 amino acids which fulfil different roles and only 20 of them form protein.

Amino acids used to make up protein can be divided into two groups:

  • essential amino acids, so called because the body cannot produce them itself so they need to be part of a regular diet.There are nine of them.
  • Non-essential amino acids, so called because the body can synthesize them itself.

Essential amino acids

There are nine of them.


Isoleucine significantly improves recovery after sport and prevents muscle catabolism.

Isoleucine helps to produce energy, improve endurance levels and is a source of energy for the muscle.

Isoleucine stabilises and regulates blood sugar levels.


Phenylalanine stimulates the thyroid gland, which secretes a hormone that regulates the nervous system and relieves pain: thyroxine.

Phenylalanine produces neurotransmitters, which are used to send information to and from the brain. It therefore plays a part in learning and memorisation.

Phenylalanine is a natural antidepressant and the body turns it into dopamine, noradrenaline and adrenaline, which are essential molecules for the transmission of nerve impulses.

Phenylalanine also helps to regulate appetite.


Valine is a natural stimulant and contributes to the correct functioning of the nervous system. Valine produces energy. It is quickly absorbed and distributed to the muscles immediately.

Valine helps to repair muscle tissue.


Methionine is a powerful antioxidant which neutralizes free radicals and helps to prevent ageing. It is also an antitoxin and antifatigue agent.

Methionine also reduces histamine and cholesterol levels by stimulating the production of lecithin in the liver, which promotes the fluidity of cell membranes.

Methionine helps to break down lipids and prevents them from building up in the liver and arteries.

Methionine is the precursor of cysteine and taurine which help muscle recovery.

Methionine enables vitamin B9 uptake and improves zinc absorption.


Leucine is a muscle stimulant. It provides the muscles with energy by stimulating protein production.It helps muscle regeneration and repair.

Leucine reduces blood sugar levels by stimulating insulin release.

Leucine aids growth hormone synthesis.


Threonine helps to form elastin and collagen which are required for cartilage and ligament growth.

Threonine helps to balance protein levels in the body.

Threonine helps to ensure a healthy digestive system by facilitating the exchange of nutrients between the intestine and blood. It also helps to disperse fat in the liver.


Lysine helps to form antibodies and regenerate damaged tissue. It contributes to the metabolism of carbohydrates and helps fat absorption. It facilitates collagen formation in combination with vitamin C.

In children, lysine is necessary for bone growth and development. It also boosts calcium absorption in adults.


Tryptophan is a precursor of serotonin. It is a calming agent and antidepressant and aids sleep.

Tryptophan helps to ensure a healthy nervous system, stabilizes moods and reduces appetite. It helps the action of B vitamins and enables vitamin B3 synthesis, reduces carbohydrate requirements and increases blood sugar levels.

Tryptophan stimulates the release of the growth hormone.


Histidine is an essential amino acid during growth. It helps to repair tissue.

Histidine is vital for haemoglobin synthesis and is found in the pancreatic enzymes which digest proteins.

Histidine helps to lower blood pressure. It is required for red and white blood cell synthesis.

The BCAA (Branched Chain Amino Acids)

The BCAA, still called amino acids, include three amino acids: leucine, isoleucine and valine.Between them, the BCAA make up around one third of muscle protein.

Out the three of them, leucine has the most powerful anabolic action, but it needs to other two to produce a lasting effect.

The BCAAs are used in muscle contraction, but not only that, because over sustained periods of effort the body uses the muscles' BCAAs to produce energy.

BCAA intake therefore optimises recovery and muscle gain during rest periods.Recent studies also prove the benefits of taking BCAA during effort, not only to limit the muscle damage incurred but also to preserve muscle glycogen stores, as it is their depletion during exercise that causes the onset of fatigue.

Glutamine and sport

Glutamine is an amino acid which belongs to the non-essential family of amino acids. In people who train regularly, glutamine should be considered as an essential amino acid because the body’s ability to synthesize it is considerably lower than the depletion caused by effort. Our muscles account for around 70% of our total glutamine synthesis.

Glutamine is the most abundant amino acid in the body. It represents about two thirds of the free amino acids in our muscles. There is a close correlation between the level of free glutamine in muscles and the ability to synthesize proteins. The higher the glutamine level, the more powerful anabolism is.

Glutamine also plays a key role in immunity due to its ability to help intestinal cells to heal. Physical effort impairs the intestine’s cells which are the body’s first line of defence. For example, the shock incurred when running is very damaging to intestinal cells.

Marie Fauchille
Dietician | Nutritionist
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