Bodybuilding usually refers to increasing and sculpting muscle mass for appearance as well as strength. In a more general sense, bodybuilding can refer to increasing muscle mass and function for the purpose of competing in sports such as football or power sports (e.g., shot putting, discus throwing, etc.). It is a given that bodybuilding requires resistance training. If bodybuilding is for the purpose of improving competitive performance in a specific sport there are likely to be training requirements unique to that sport. This discussion on amino acids for bodybuilding will, therefore, not focus on the specific aspects of training. Regardless of the goal of training, amino acids play a key role in bodybuilding.
Muscle Protein Turnover—the Metabolic Basis for Increased Muscle Mass, Strength, and Function
Muscle function is accomplished by the contraction of muscle protein fibers. Muscle strength and function are determined by how many muscle protein fibers you have and the efficiency with which they contract. Increasing muscle protein mass and contractile efficiency is accomplished by optimizing muscle protein turnover.
Muscle protein turnover refers to the constant breakdown of older muscle proteins that are no longer operating at peak efficiency and replacing them with newly synthesized, more efficient muscle protein fibers. The balance between protein synthesis and breakdown determines whether a muscle is growing or shrinking.
For bodybuilding, the goal is to make the rate of muscle protein synthesis exceed the rate of protein breakdown. Further, the increased balance between muscle protein synthesis and breakdown should optimally be accomplished mainly by stimulating synthesis—protein breakdown gets rid of muscle proteins that are not functioning efficiently, so it is good to keep that process functioning at full speed.
Muscle Protein Synthesis
Muscle proteins are composed of a series of amino acids hooked together in a specific order determined by the messenger RNA (mRNA) in the cell for each specific muscle protein. The sequence of the mRNA is dictated by the DNA in the cell. There is a specific molecule for each amino acid (tRNA) that delivers it to the mRNA as required for incorporation into the protein that is being produced.
A simple, conceptual way to think about the process of muscle protein synthesis is to compare it to the construction of a building. The DNA is basically the idea for the design of the building. The RNA is the written plan or blueprint, and transcription of the mRNA from the DNA is the process of writing up the plan. The tRNA molecules that bring the amino acids to the mRNA for incorporation into protein are like trucks that bring bricks to the building site, and the hooking of amino acids together in the proper order on the mRNA corresponds to the builder “putting the bricks together” according to the blueprint. The protein is the final product, or completed building, ready to serve its function.
The details of how muscle protein is made is important only so that is it clear why all the amino acids must be available in abundance. If the mRNA dictates that the next amino acid in the chain making up the protein is a particular amino acid that is deficient, then the process is halted and no muscle protein is produced.
Amino Acids and Protein Synthesis
The amino acids that must be obtained from the diet are called essential amino acids (EAAs). Amino acids that can be made in the body are called nonessential amino acids (NEAAS).
The nine EAAs are leucine, isoleucine, valine (the three branched-chain amino acids called the BCAAs), phenylalanine, lysine, methionine, phenylalanine, threonine, and tryptophan. There are 11 NEAAS that are components of human protein, although there are other NEAAs—like citrulline and ornithine—also in the body. The availability of EAAs is the key to the rate of muscle protein synthesis. NEAAS are available in abundance.
EAAs and Muscle Protein Synthesis
Consuming EAAs, either as dietary protein or supplements, is the most potent stimulus of muscle protein synthesis. Consuming NEAAs, either alone or with EAAs, has no impact.
EAA supplements have been shown to trigger muscle protein synthesis and increase muscle mass, strength, and physical function in at least 25 clinical trials. The muscle-building response to EAAs is 2-4 times greater than the muscle-building response to the same amount of a whey protein supplement. The muscle-building response to EAAs is even greater than the response to hormonal treatment with testosterone, growth hormone, or insulin.
There is one very big must when it comes to EAA supplementation, however. In order to be effective, all the EAAs are required. That being said, there are varying degrees of importance among the EAAs.
Leucine, in particular, is important. Leucine is the most abundant EAA in muscle protein, so it should comprise the highest proportion of an EAA supplement. Beyond its role as a component of muscle protein, leucine can signal the molecular mechanisms within the cell to initiate the process of protein synthesis. Important as leucine may be, however, it cannot function alone. All the other EAAs are required as well, roughly in proportion to their relative content in muscle. It is not possible to make muscle protein from leucine alone.
Amino Acids for Bodybuilding
It is clear from the above discussion that making sure you consume enough EAAs is an important part of bodybuilding. Even when using EAA supplements, the main source of EAA intake is dietary protein. Therefore, the place to start is with your diet.
Protein is the key dietary component of the basic bodybuilding diet. It will increase your muscle mass. You should set a goal of eating approximately 30% of your caloric intake as high-quality protein. High-quality protein is a protein that contains a high abundance of EAAs.
High-quality proteins are generally animal-based proteins. These protein food sources also have a significant amount of non-protein calories. Therefore, eating a sufficient amount of high-quality protein to supply all the EAAs you need is difficult through normal diet alone. You will most likely run into issues with the flexibility of your diet when eating this amount of high-quality protein food sources because of the non-protein calories. Therefore, EAA supplements can play a vital role in helping you meet your dietary goal for EAA intake.
While the focus of your basic diet should be high-quality protein, you must remember that energy substrates (carbohydrates and fat) are important too. As an example, in a tightly controlled study, subjects drank the same amount of protein in the form of milk. In one case, it was skim milk, and in the other case whole milk. The stimulation of muscle protein synthesis was greater with the whole milk. Under these study conditions, the additional calories provided by the fat in the whole milk helped to fuel muscle building.
You must be in a positive energy balance to gain a significant amount of muscle mass. Carbohydrate is of less importance for resistance training than it is for endurance training, but you should eat enough fruit and vegetables to meet the RDAs for micronutrients. Also, carbohydrate intake will stimulate insulin release, and insulin is an anabolic hormone that will increase the amount of muscle protein made from your EAA intake.
Fat intake will also amplify the anabolic effect of EAAs, and therefore you can eat animal-based, high-quality protein foods without worrying about eating too much fat.
What you do want to keep in mind with your bodybuilding diet is that the more you eat, the bigger you will get. If you do eat a lot while lifting heavy weights and consuming EAA supplements as recommended, a significant part of the weight gain will be muscle.
You will also gain fat with this dietary approach, so you need to carefully monitor your body composition to be sure that the extra fat you put on does not counteract the benefits of the muscle gain. In a sport like powerlifting, that is not likely to be the case, but if you are bodybuilding for appearance, you must reach a balance between muscle and fat gains. This can be accomplished by incorporating aerobic exercise into your training program.
How to Use EAA Supplements for Bodybuilding
The research documenting the optimal use of amino acids for bodybuilding is extensive.
Consuming 15 grams of EAAs 30 minutes before starting your workout will elevate blood EAA concentrations throughout your workout and stop the breakdown of muscle protein that would otherwise occur. A 15-gram dose of EAAs achieves a greater response on muscle protein synthesis than casein or whey protein can, without creating the fullness that can hinder a workout.
Take another 15 grams of EAAs immediately after your workout, and then again one hour later. This program presumes you will be working out every day. On your off days, consume the same amount of EAAs, but instead of working them around exercise take them between meals.
Between the completion of dinner and breakfast the next morning you may be 12 hours or more without food. During this post-absorptive time muscle is breaking down to supply amino acids to tissues and organs that have no protein reserve. Therefore, for maximal muscle-building response, consume another 15 grams of EAAs before bedtime, and set your alarm for a final dose at about 4 am if you are really committed to maximizing muscle gain.
Alternatively, you can take 20 grams of casein protein at bedtime. Casein coagulates in the stomach, so the digestion of the protein is very slow and the resultant amino acids are absorbed over many hours. The anabolic effect will be less than if you take the EAAs, but it will save you the trouble of getting up in the middle of the night.
The total amount of supplemental EAAs should be in the range of 60 grams per day. Consuming this amount of EAAs will stimulate the production of new muscle protein without you having to also take in a significant amount of non-protein calories. The result will be a lean body with increased muscle mass and minimal increase in fat mass. Sixty grams of EAAs in addition to what you eat as part of your bodybuilding diet is needed to drive protein synthesis past what may be your normal genetic limitation.
What Are the Side Effects of EAA Supplements?
This a reasonable question, because bodybuilding requires a much greater level of EAA intake than normal. The fact that it is only EAAs in the supplement is important in this regard. An unusually high amount of dietary protein intake will increase the rate of amino acid oxidation and as a result, burden the kidneys to excrete the ammonia and urea that are natural byproducts of NEAA oxidation.
Here’s the great thing about EAA supplements: there is no such increased oxidation of NEAAs when EAAs are consumed. This is because NEAAs are not also being consumed but are rather being produced in the body. In fact, the oxidation of the NEAAs actually goes down, since they are being incorporated into protein at an increased rate.
Consequently, there is no reason to worry about the side effects of EAA supplements or safety. EAAs have been ruled to be Generally Regarded as Safe (GRAS) by the FDA, and the Food and Nutrition Board of the National Academy of Science has determined that there is no upper limit of consumption beyond which would not be safe.