It’s well known that protein is a vital nutrient and one that’s need is increased when exercising especially if strength, muscle size and performance is your goal. Whilst protein as a whole is increased there is something to be said for particular amino acids and the benefits they can offer as individual nutrients rather than just total protein consumption.
The three amino acids Leucine, Isoleucine, and Valine are the Branched chain amino acids. They are three of the essential amino acids and as the name implies they have a branched chain on their chemical structure which makes them different from other amino acids.
BCAA (branched chain amino acids) make up around 10-14% of the total amino acids in muscle proteins within the body. BCAAs can be found in most animal foods such as meats and diary as well as in nuts and soya but to a much lower extent.
Typically, there are two major benefits which can be attributed to BCAA in regards to someone who is seeking performance or body composition gains.
Enhanced protein synthesis
This is the one which has had the most recognition over the past few years and with good reason as it appears that one of the amino acids namely Leucine plays a crucial role in what is termed the anabolic switch in creating growth within muscle.
Leucine promotes protein synthesis and inhibits protein degradation via mechanisms involving the mTOR activation (Target of Rapamycin in mammals). With leucine influencing mTOR which in turn activates protein synthesis which is much in the same way that resistance training activates MTOR to signal to build muscle. As can be seen a combination of resistance training and leucine would be the best options for signalling muscle growth.
This action is independent of one of the major signallers of mTOR which is Insulin1, this is important as those looking to keep calories and carbohydrates low can still reap the benefits of increased protein synthesis activation
As well as increasing muscle growth it would appear that BCAAs can also protect against muscle loss whilst in a low calorie state. Recent research showed that BCAAs prevented muscle loss whilst participants lost fat in a lowered calorie diet whilst those taking carbohydrates lost fat and muscle!2
What was also pertinent was those taking BCAA increased their strength more than the carbohydrate group as well. Evidently from this BCAAs can not only activate muscle growth but also assist in maintaining muscle and strength during periods of fat loss.
Central fatigue opposition BCAAs are stated to delay the onset of fatigue through the central fatigue theory. It is stated that fatigue can be linked to tryptophan (Trp) and 5-hydroxytriptamine (5HT). BCAAs have been reported to act as a defence of 5HTP by acting to block Trp from being uptaken within the brain.
During exercise BCAAs are up-taken into the muscle decreasing BCAA concertation within the blood, this combined with increased Trp concentration due to free fatty acids competing with Trp. In a nutshell during exercise BCAA levels drop whilst Trp Levels increase. This leads to higher levels of Trp in the brain which results in higher production of 5HT and subsequently higher levels of fatigue.
Considering this it’s been suggested that increasing BCAA concentrations during exercise through oral ingestion will halt increased 5HT and prevent earlier fatigue* 3,4.
Why 8:1:1 ratio
Typically in foods and mainly mainstream BCAAs supplements the ratio amongst the three amino acids (Leucine, Isoleucine, and Valine) is often 2:1:1 and whilst there is still benefit to consuming BCAAs in this ratio it would not be deemed optimal. If you look at the above benefits the main active ingredient in these tends to leucine, as such to get the optimal dosing of Leucine you would need to consume significant quantities of BCAAs if they are in a 2:1:1 ratio. By increasing the leucine content, the benefits of BCAA supplementation can be obtained in smaller quantities.
This optimal configuration of BCAAs makes it beneficial in two ways, firstly you don’t need to take BCAAs in excess which is great if in a very tightly controlled calorie diet but secondly you need to spend less to get the optimal dosage and reap the benefits.
In a nutshell who can benefit from increased BCAA intake? The following people would be wise to consider an increase in BCAA ingestion
- Those looking to increase muscle growth and protein synthesis
- Those looking to retain muscle mass whilst dieting
- Those looking to delay fatigue during training or sporting competition
1. Gran et al. 2011 The actions of exogenous leucine on mTOR signalling and amino acid transporters in human myotubes. BMC Physiology
2.Dudgeon et al 2016. In a single blind, matched group design: Branch chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet. Journal of the international society of sports nutrition.
3. Gualano et al. 2011. Branched chain amino acids supplementation enhances exercise capacity and lipid oxidation during endurance exercise after muscle glycogen depletion. Journal of sports medicine and physical fitness
4.Hassmen et al 1994. Branched chain amino acid supplementation during 30km competitive run: mood and cognitivie performance. Nutrition