As a strength or fitness athlete, we don’t need to preach the importance of consuming enough protein to you, right? Chances are you’ve heard it many times before- without adequate protein consumption, you are likely to have a hard time getting where you want to be.
But it’s time to look a little deeper; into the constituents that make up proteins, the amino acids. Are they all created the same? Not at all. Amino acids can be classified as non-essential (the ones the body can make on its own), semi-essential (conditional need), or essential, the ones we must get from our diet.
They are all important to varying degrees, but one small subcategory of three essential amino acids, known as the branched chain amino acids, or BCAAs, play an exceedingly important part in the muscle growth equation.
And the one that stands above them all? That would be L-Leucine without a doubt. But what exactly makes L-Leucine the VIP? Read on below to find out.
The body’s primary source of energy during workouts is glucose (obtained from carbohydrate rich foods), but in the absence of this fuel, it needs to start looking elsewhere[i]. Fat is a viable alternative, as the production of ketone bodies is a decent substitute, but fat adaptation takes some time and generally requires a low carbohydrate diet to begin with.
These mitigating factors aside, BCAAs, inclusive of leucine, are capable of converting to glutamine or alanine, which is subsequently converted into glucose via the process of gluconeogenesis. This process acts as an alternative means for glucose production in the absence of carbohydrate consumption, and is usually employed as a fail-safe for organs such as the brain which preferentially run on glucose.
By making this alternative energy source available, you are likely to complete the workout you set out to accomplish, and not fail for lack of energy half way through.
Increases Post-Workout Muscle Protein Synthesis
The most attractive draw of L-Leucine would have to be its ability to enhance post-workout muscle recovery and kick-start protein synthesis, since this is the reason most of us hit the gym, right?
L-Leucine helps accomplish this not only by taking advantage of the anabolic window following your workout, but also enhances the activity of two other muscle building pathways, mTOR[ii] and AKT by 49% and 98% respectively, in studies conducted on rodents.
Humans also possess these muscle building pathways, and the supplementation of L-Leucine seems to corroborate this finding. There also appears to be a point beyond which not much benefit is obtained from leucine supplementation, but which when achieved helps to “trip” the switch on muscle protein synthesis.
Reduces Protein Degradation
Protein degradation, also known as protein breakdown or catabolism, is an unavoidable consequence of weight training. In the process, BCAA stores in muscles are rapidly depleted, fostering an environment that is not in the best interest of muscle gain.
Muscle breakdown is inevitable during intense training, and is the necessary stimulus that sets the stage for rebuilding of larger, stronger muscle fibres, but only if you arrest it with timely nutrition. L-Leucine, taken along with the other BCAAs prior to, after and even during your workout can effectively flip the script and ensure optimal recovery and a switch to anabolism.
Have you been hit by a bad case of DOMS? DOMS, better known as delayed onset muscle soreness, is that too familiar session of pain that kicks in a day or two after you’ve had an intense workout. While not technically bad, as it gives fair indication that you had subjected your muscles to sufficient workload, it leaves you in more discomfort that you should have to bear.
L-Leucine, it turns out, may offer solace by helping to blunt the amount of pain experienced during this interval. This effect has much to thank owing to its ability to reduce muscle breakdown[iii], which coincides with the extent of muscle damage incurred during training.
Levels of creatine kinase- associated with muscle damage, are also lower when L-Leucine is supplemented, according to findings published[iv] in The Journal of the International Society of Sports Nutrition in 2012.
Leucine Is Highly Anabolic
When most people hear the word “anabolic”, thoughts immediately race through their minds about testosterone and other related steroidal compounds. But how about another hormone, that isn’t a steroid, but instead a peptide?
We’re talking about insulin, one of the body’s most potent anabolic hormones that can help you add pounds of muscle to your frame if utilized the correct way. Given, insulin can also make you very fat since it is primarily a storage hormone.
In order to take advantage of its staggering muscle building capacity, it is best put to use at the peri-workout window. This included both pre and during your workout, plus afterwards- the time it shines the most.
L-Leucine is a strong insulin stimulating agent[v], capable of triggering its release once present in the blood. Whey protein contains a high amount of leucine as well, but to get the maximum benefit from it at the post-workout interval, opt for a straight leucine or BCAA product, as its absorption is much faster than whey.
This will help ensure that muscles preferentially become saturated with these aminos following your workout, while the cavalry; dextrose and whey, are on the way.
While L-Leucine is found in many protein rich foods and powders, when you are trying to maximize protein synthesis following your workout, you need to either use a BCAA or dedicates L-Leucine supplement for maximum speed of absorption. Try to shoot for 2.5g at this interval (and a total of 10g over the course of the day, split into 4 servings) for a great way to end your workout and begin the process of muscle growth.
[i] Duan, Y., Li, F., Li, Y. et al. Amino Acids (2016) 48: 41. https://doi.org/10.1007/s00726-015-2067-1
[ii] Anthony JC, Yoshizawa F, Anthony TG, Vary TC, Jefferson LS, Kimball SR.Leucine stimulates translation initiation in skeletal muscle of postabsorptive rats via a rapamycin-sensitive pathway. J Nutr. 2000 Oct;130(10):2413-9. PubMed PMID: 11015466
[iii] Shimomura Y, Murakami T, Nakai N, Nagasaki M, Harris RA. Exercise promotes BCAA catabolism: effects of BCAA supplementation on skeletal muscle during exercise. J Nutr. 2004 Jun;134(6 Suppl):1583S-1587S. doi: 10.1093/jn/134.6.1583S.Review. PubMed PMID: 15173434.
[iv] Howatson G, Hoad M, Goodall S, Tallent J, Bell PG, French DN. Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: a randomized, double-blind, placebo controlled study. J Int Soc Sports Nutr. 2012;9:20. Published 2012 Jul 12. doi:10.1186/1550-2783-9-20
[v] Yang J, Chi Y, Burkhardt BR, Guan Y, Wolf BA. Leucine metabolism in regulation of insulin secretion from pancreatic beta cells. Nutr Rev. 2010;68(5):270–279. doi:10.1111/j.1753-4887.2010.00282.x