Jogging. Swimming. Cycling. Dancing. What do all these activities have in common? They’re aerobic, which means the heart is pumping oxygen-rich blood to your working muscles. Your heart is beating faster, blood is flowing from your muscles to your lungs, and you’re producing endorphins, those feel-good hormones that naturally put you in a better mood. The benefits of amino acid supplements for bodybuilders striving to increase their muscle growth are quite well-known, but the ways amino acids can enhance the effect of aerobic exercise receive less attention.
Here's what you need to know in order to combine essential amino acid (EAA) supplements with aerobic exercise for maximum benefits.
What Are Essential Amino Acids (EAAs)?
There are many different types of amino acids as well as a variety of ways to divide them into categories. In terms of dietary supplements, however, two specific groups of amino acids unequivocally reign supreme: essential amino acids (EAAs) and branched-chain amino acids (BCAAs). You can read this article if you're interested in a more thorough run-down of the differences between the two, but for now, it's sufficient to understand that the term branched-chain amino acids refers to a subgroup of three essential amino acids: leucine, isoleucine, and valine.
The reason essential amino acids are referred to as essential is that, unlike the other 11 nonessential amino acids, your body cannot synthesize them de novo. Instead, it requires an external supply of these vital amino acids from the food you eat or other sources, such as supplements. There are nine EAAs total:
Each EAA has its own distinct and important functions within the human body. Some of these amino acids, like the three BCAAs, have particularly exciting effects. Valine, for instance, helps prevent the erosion of muscle mass during exercise. This limits muscle damage and post-workout soreness, helping you to recover more quickly and perform at full function again faster.
What many people do not fully grasp, however, in part because of the misleading claims put forth by unethical manufacturers, is that it is impossible to access the benefits of any single EAA without a supplemental, well-balanced dose of the remaining eight EAAs.
Why EAA Supplements Outperform BCAA Supplements
Much of the research on the benefits of amino acid supplements for improving exercise performance has been focused on the use of BCAAs rather than on essential amino acid supplements. As we explained in the previous section, however, solely increasing your intake of BCAAs will not allow you to obtain the full benefits associated with those amino acids. In order to bring about the positive changes you desire, you must provide your body with an optimally balanced dose of all the EAAs.
To illuminate why that is, let's look at a specific amino acid: leucine, one of three branched-chain amino acids (BCAAs) and the most abundant essential amino acid in muscle.
Leucine promotes muscle recovery after vigorous workouts, boosts stamina and endurance, and enhances anabolism (the muscle-building component of the muscle protein synthesis process). But, unlike other essential amino acids, leucine (and its BCAA comrades isoleucine and valine) undergoes oxidative degradation during aerobic exercise.
Given that the body can use leucine for energy during aerobic exercise, it may seem reasonable to supply extra leucine to offset the oxidation that transpires during the muscle protein breakdown process. Here’s where things get muddled.
When you introduce more leucine or BCAAs into the bloodstream, a greater percentage is oxidized. That’s because the body is designed to keep a balanced composition of amino acids available in the blood, so mechanisms kick in to reduce the leucine you’ve ingested.
To avoid that dilemma, it's best to take a supplement containing all nine essential amino acids.
A 2018 study conducted by researchers from the University of Texas looked at the effect of EAAs and aerobic exercise on skeletal muscle protein anabolism. The goal of the Phase 1, double-blind, placebo-controlled, randomized clinical trial was to determine if ongoing EAA supplementation with 15 grams taken daily, supervised aerobic training 3 days weekly, or a combination of the two interventions could increase muscle mass and function by stimulating muscle protein synthesis.
The researchers measured muscle strength, physical function, body weight and composition, and muscle protein synthesis both before and after the 24-week trial. Only participants who took the EAA supplement showed improvements to muscle strength and muscle protein synthesis.
Timing Your EAA Supplement Doses for Maximum Impact
Though the study cited above did not specify the times at which participants took their EAA supplements, scientists have found that due to the oxidation of BCAAs that transpires during aerobic exercise, the time at which you take your supplements can markedly impact the extent of the benefits you experience.
Pre-Workout EAA Supplements: The Bottom Line
The efficiency of the supplement is considerably reduced when taken pre-workout or during aerobic exercise when the metabolic pathways of BCAA oxidation are already revved up. Consequently, the supplemental leucine or BCAAs will not be available to promote muscle protein turnover.
Nonetheless, ingesting leucine or BCAAs before or during exercise will offset to some extent the accelerated oxidation of these amino acids, as long as all the EAAs are provided. Perhaps more importantly, increasing BCAAs and phenylalanine during exercise encourages the synthesis of the excitatory neurotransmitter dopamine relative to the depressant neurotransmitter serotonin. This can improve mental focus and delay the perception of fatigue.
While it won't impede your progress or cause any adverse effects if you take an EAA supplement before your workout, the post-exercise use of EAAs can provide far more significant benefits.
Post-Workout EAA Supplements: The Bottom Line
Replenishing your body's stores of EAAs after an aerobic workout can help to maximize the positive impact of your hard work. The post-workout benefits of EAA supplements are especially pronounced when taken the first hour after aerobic exercise.
EAAs produce a potent anabolic effect, serving as the key precursors for increased protein turnover. An increase in muscle protein turnover is the metabolic basis for improved muscle fiber functioning. In addition, EAAs increase the production and functioning of the mitochondria, the site in each cell where energy production takes place These responses can only be achieved with a formulation containing all of the EAAs, since all EAAs function as building blocks from which new proteins are formed.
While BCAAs alone are not effective, the optimal EAA formulation for post-aerobic-exercise supplementation should have a higher proportion of BCAAs in the total mixture than is represented in the composition of muscle protein in order to restore the BCAAS that were metabolized during exercise.