Whether you’re eating a lean fillet steak for dinner or downing a whey protein shake after your workout, the goal is the same. The aim of consuming all this protein is to flood your system with amino acids, the building blocks of muscle.
Amino acids are organic compounds that are biologically significant to the anabolyc process as they aid muscle protein synthesis. They also fulfill other vital roles in the body by acting as neurotransmitters, signal hormone release via their transport function and are components of haemoglobin, cell membranes, fibrin (for clotting) and contractile elements. This means that they are also closely linked with disease prevention, mental health and the optimal functioning of our internal, endocrine and musculoskeletal systems.
By understanding the role that amino acids play in the body and how to manipulate your intake you can take your growth to a whole new level.
But before delving into the practical elements of amino acids let’s get the science and biology out of the way.
Amino acids are made from two funcional groups, namely an amine (-NH2) and a carboxylic (organic) acid (-COOH) functional group, along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen and nitrogen.
There are about 600 known amino acids, which can be classified in various ways.
Of most relevance to bodybuilders, amino acids are the second largest constituent of human muscle tissue (water is the largest constituent). Dor the purpose of this article we will focus on the roles that amino acids play in terms of muscle growth, from a structural and biological perspective.
Twenty-two amino acids are naturally incorporated into polypeptides (proteins) and are called proteinogenic or natural amino acids. Of these, 20 are encoded by the universal genetic code. The remaining two – selenocysteine and pyrrolysine – are incorporated into proteins by unique synthetic mechanisms. there are many other amino acids that are called non-proteinogenic or non-standard that are either non found in proteins, such as carnithine and GABA, or are not produced directly and in isolation by standard cellular structures.
Of the 20 standard amino acidsthat are most relevant to bodybuilders, nine are considered essential amino acids (EAA) because they cannot be created from other compounds by the human body. As such they must be supplied through our diets from whole food and supplements. Other amino acids may be considered conditionally essential in certain instances, like during times of illness, stress or excessive exercise. Conditionally essential amino acids incclude arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline and serine. There are also non-essential amino acids (NEAA) that are provided by the liver.
Role in protein synthesis
Amino acids build muscle by forming the structural units of proteins, they achieve this by joining together to form short polymer chains called peptides through a process known as dehydration synthesis. These peptides then form longer chains of 10 or more peptides called polypeptides.
A polypeptide that contains more than 50 amino acids is generally cconsidered to be a protein molecule, depending on the manner in which they are bound together. These are the building blocks of muscle, These polymers are linear and unbranched, with each amino acid within the chain attached to two neighboring amino acids. The process of making proteins is called translation and involves the step-by-step addition of amino acids to a growing protein chain by a ribosome. The order in which the amino acids are added is read through a person’s genetic code from an mRNA template, which is an RNA copy of a gene.
In order for protein synthesis to occur an adequate supply of both essential and non-essential amino acids is vital. If one of the essential amino acids is missing then the pronein synthesis can stop. When we onsume amino acids, in the form of either whole food or supplements, the 20 standard amino acids are either used to synthesise proteins and other biomolecules, or are oxidised to urea and carbon dioxide as a source of energy, depending on the needs of the body at the time.
The body’s priority will always be to obtain sufficient energy to maintain vital functions such as circulation, respiration and digestion. Therefore, in the absence of adequate dietary carbohydrates and fat calories, the body will catabolise dietary protein or use protein from the blood, liver, pancreas, muscles and other tissues in order to maintain vital organs and functions. This is when glucogenic amino acids are converted into glucose, through the process of gluconeogenesis.
However, when amino-acids are used as a fuel source muscles appear to preferentially utilise the Branched Chain Amino Acids (BCAA) leucine, isoleucine and valine.
In order for protein synthesis to occur, an adequate supply of both essential and non-essential amino acids is vital. If one of the essential amino acids is missing, then protein synthesis can stop.
Best sources of essential amino acids
- Whey protein
- Amino acid supplements: complete (blends) or individual (free form) amino acid products and BCAAs.
- Animal protein: meat, chicken, turkey, venison, eggs and dairy
- Vegetarian protein: beans, seeds (which only provide incomplete proteins) and soy (a complete protein)
Protein digestion begins in the stomach, where pepsin cleaves amino acid bonds to break proteins down into their polypeptides and small amounts of free amino acids. When these protein ‘fragments’ enter the small intestine enzymes cleave them into peptides and amino acids are liberated one at a time. The amino acids then enter the bloodstream via the capillary beds in the small intestine. These free amino acids form an amino acid pool and are then transported in the blood to the cell structures that require them, including muscle cells, which use them to replace tissue proteins.
This means the more complex the protein structure the longer the process takes for amino acids to enter the bloodstream. As such, supplementing with a suitable amino acid product makes amino acids immediately available for absorption and transport to damaged muscle cells.
The bioavailability a protein is the key measure of its ability to be used by the body. The higher the biological value (BV) the more readily the body can absorb the protein and convert it to amino acid form.
- Whey protein blended (hydrolysed) BV= 100-159
- Whey BV = 104
- Eggs BV = 100
- Cow’s milk BV = 91
- Egg white BV = 88
- Beef BV = 80
- Fish BV = 79
- Chicken BV = 77
- Casein BV = 77
- Soy BV = 74
AMINO ACID TIMING
Various studies have highlighted the importance of using amino acid supplements before and/or during exercise. This is due to the high bioavailability of the amino acids, which means they are used to repair muscle cells as the damage occurs. This approach can also spare muscle by providing free amino acids in the bloodstream for energy production if required.
A 2001 Texas study published in the “American Journal of Physiology-Endocrinology and Metabolism” had participants consume amino acid- carbohydrate supplements prior to exercising on one trial, and after exercising on the other trial. Uptake of the supplement by the muscles was greater when consumed pre-exercise, suggesting that supplementing amino acids before your workout may be more beneficial.
Another reason for this is that amino acids cannot be stored for use at a later stage, like glucose (in the form of stored muscle and liver glycogen) or free fatty acids. This means you need to supply your body with the amino acids it needs during exercise, not just after it.
A whole food meal that is rich in protein can also be eaten before a workout, but this may result in digestive discomfort if eaten too close to your workout, which may impact on performance. Unfortunately, a high protein meal won’t deliver significant amounts of amino acids into your bloodstream immediately. It can take up to a hour or more to digest, especially if blood flow to the gastrointestinal tract has been diminished due to post-exercise peripheral blood flow demands. The composition of your meal can also impeded the delivery of amino acids to muscle cells as fat is a rate-limiting factor in gastric emptying. Cooking can also affect amino acids as some are sensitive to heat. As such the cooking process may cause amino acid decomposition.
The most reliable way to deliver amino acids to working muscles is to ingest specific amino acids in free form. Free form amino acid supplements do not require any digestion and are free of chemical bonds to other molecules. This means that they can move quickly through the stomach and into the small intestine, where they are rapidly absorbed into the bloodstream.
The 1-2 hour post-exercise anabolic window and first thing in the morning (after waking from sleep in a fasted state) are the two most important times when you need to ingest a significant amount of protein to deliver amino acids to muscles.
Whey protein, free form amino acid products and/or amino acid blends are the ideal sources in the post-exercise anabolic window to ensure the rapid delivery of amino acids to muscles.
Supporting this notion is a study conducted by the Department of Surgery, Shriners Hospital for Children/Galveston, University of Texas Medical Branch in 2001. It determined that the ingestion of a relatively small amount (6g) of orally administered EAAs stimulated net muscle protein balance in healthy volunteers when consumed one and two hours after resistance exercise.
These supplements can then be followed by whole food meals that are rich in protein to continue to the amino acid ‘trickle effect’ and maintain an anabolic state. Various studies have also found a correlation between amino acid ingestion and the retention of muscle mass during rest or periods of immobility.
AMINO ACID SUPPLEMENTS
When using amino acids in supplemental form, consider sticking to L-form amino acids. The ‘L’ before the amino acid name, for example L-glutamine, refers to the structure of the amino acid.
It indicates that the amino acid is in a human form and is therefore easier to digest and assimilate.
Amino acid ratios can also be manipulated to elicit other important anabolic responses. For instance, certain amino acid combinations can prompt the release of important hormones. These combinations can up-regulate natural hormone production, negating the need to introduce exogenous hormones and other anabolic substances into the system.
A number of products on the market, like Human Growth Hormone (HGH) boosters and precursors, use pre-dosed amino acid ratios to stimulate the natural secretion of HGH from the pituitary gland and hypothalamus. This is generally done through the combination of a number of amino acids, the most important being L-glutamine, L-arginine, L-ornithine and L-lysine, along with growth hormone releasing peptides.
Certain amino acids have a synergistic effect on each other when combined in certain ratios, as opposed to using them individually. As an example, arginine AAKG, which is far better than the HCL version due to its high bioavailability, increases the release of HGH in its own right. However, when you combine ornithine and lysine with it, it boosts the effect of the arginine by about four times.
Glutamine is also an important amino acid as it both enhances muscular protein synthesis and increases circulating growth hormone levels.
The combination of these amino acids, along with other important substances will work in a number of phases to up-regulate the body’s pituitary response and amino acid potentiation systems. The pituitary response system is up-regulated by HGH boosters as they increase the release of powerful substances called secretagogues, which prompt the endocrine system to secrete hormones, in this case growth hormone. The secretagogues that stimulate HGH production are also said to suppress somatostatin production, which is a hormone produced by a number of organs in the body that inhibits the secretion of growth hormone.
Certain amino acid combinations can prompt the release of important hormones, these combinations can up-regulate natural hormone production negating the need to introduce exogenous hormones and other anabolic substances into the system.
The most reliable way to deliver amino acids to working muscles is to ingest specific amino acids in free form.
IMPORTANT AMINO ACIDS FOR BODYBUILDING
BCAAs, so named because of their unique chemical structure (a basic tree with branches), are metabolised directly in the muscle and can be converted into energy to prevent muscle catabolism. If you supplement with BCAAs the body does not have to break down muscle tissue to derive extra energy. A study conducted at the School of Human Biology, University of Guelph, Ontario, Canada, confirmed that the use of BCAAs (up to 4g) during and after exercise could result in a significant reduction of muscle catabolism during exercise.
Glutamine is the most abundant amino acid found in muscles and can account for as much as 60% of the free amino acids in skeletal muscle. Glutamine positively affects growth hormone maintenance, cell volume, immune function and protein substrate recycling for enhanced protein synthesis in muscle.
Taurine is the second most abundant amino acid in muscle. Taurine plays an important role in cell volumisation, which can boost hydration that results in a higher rate of protein synthesis.
Arginine is an amino acid that is conditionally essential in certain instances. Arginine plays a pivotal role in creatine production and is also critical for the production of growth hormone. Arginine also helps to remove excess nitrogenous ammonia, which is developed during the protein urea cycle.