There's no shortage of products available to suit whatever need you're looking for when it comes to fitness supplements.
They come in a wide variety of forms, from the traditional protein shakes and mass gainers to the highly specific creatine, HMB, or amino acids that offer precision support pre-, intra-, and post-workout.
For those unfamiliar with the world of fitness supplements, it can be a challenge to navigate through what will work for your goals, never mind how to actually use it.
With a quick internet search, you'll return hundreds of websites giving you the rundown of what to take, when to take it, and what it does.
But one of the more common questions around fitness supplements is whether they're safe to consume on non-training days, especially regarding things like amino acid supplements.
So in lieu of the questions, we're going to set the facts straight—do BCAAs have a place in your diet on off days? Read on as we outline everything you need to know.
The Basics: What Do BCAAs Do?
Knowing why BCAAs may be beneficial to take on off days comes down to understanding the branched-chain amino acids' role in the body and for athletic performance.
There are four major functions of the BCAAs:
1. Promote Muscle Growth
The #1 draw for BCAAs is their ability to boost muscle growth because they contain concentrated amounts of leucine; generally speaking, you'll see a 2:1 ratio of leucine to isoleucine and valine, and that's because leucine plays an essential role in protein metabolism by promoting protein synthesis and inhibiting protein degradation via mechanisms involving the mammalian target of rapamycin (mTOR).
Studies suggest that the anabolic effects of the BCAAs are likely to be mediated through changes in signaling pathways controlling protein synthesis, which involve phosphorylation of mTOR and the subsequent activation of p70 S6 kinase and the eukaryotic initiation factor 4E-binding protein 1 1.
But for MPS to occur, all 20 amino acids—the 9 essentials and 11 non-essentials—that make up a muscle protein must be present.
So, solely taking a BCAA hoping to stimulate MPS unfortunately won't work. Still, it does boost the amount of leucine available to enhance muscle protein synthesis after resistance training by activating mTOR, which eventually affects translation initiation and elongation of proteins 2-4—boom, muscle growth.
2. Accelerate Recovery and Reduce Muscle Soreness
Exercise damages muscles—we all know that. And we've all experienced the three days of pain that can follow an intense workout.
But according to research, BCAA supplementation may help to attenuate muscle damage and speed up recovery. This is one of the major reasons BCAAs can be beneficial on off-days; we'll talk more about this below.
Resistance exercises cause micro-damage in muscle fibers, which can lead to delayed onset muscle soreness (DOMS), reductions in strength and force production, along with an increased efflux of intramuscular proteins into the blood.
And for people who regularly engage in strenuous exercise without proper repair, the damage may accumulate and become chronic, leading to poor recovery, increased discomfort, and diminished performance.
Protein and amino acid supplements, however, are shown to be an effective intervention for enhancing recovery.
Research shows that BCAAs may reduce protein degradation and/or muscle enzyme release, decrease skeletal muscle damage in response to resistance training, reduce muscle soreness, mitigate central fatigue, and accelerate muscle recovery post exercise 5.
3. Reduce Fatigue
If you didn't think about BCAAs helping to reduce fatigue, think again. Some studies show amino acids may be involved in energy production and reducing the accumulation of fatigue-inducing compounds like 5-HT (serotonin), lactate, and ammonia during physical exertion.
One study looked at the effects of BCAA consumption on markers of fatigue and found that participants ingesting BCAAs had lower levels of serotonin, creatine kinase (CK), and lactate dehydrogenase (LDH) 6 compared to those taking a placebo. Accumulation of these substances during endurance exercise may impair exercise performance.
Researchers suggest BCAAs may reduce central fatigue by altering brain concentrations of 5-hydroxytryptamine (5-HT) that induce fatigue. But despite this, tryptophan, the precursor to 5-HT, transport across the blood-brain barrier (BBB) is the rate-limiting step in the synthesis of 5-HT; thus, it largely controls perceived and experienced fatigue.
However, studies have demonstrated plasma ratio of free tryptophan to BCAAs increases during physical activity so that tryptophan is taken up preferentially by the brain, which may increase the synthesis of 5-HT 7 and thus increase fatigue.
Although, because larger amino acids like leucine, isoleucine, and valine use the same transport proteins as tryptophan to cross the BBB, increasing plasma concentrations of BCAAs would theoretically reduce tryptophan uptake and the subsequent synthesis of 5-HT, thereby delaying the onset of fatigue.
4. Prevent Muscle Loss
For times when the body is in a caloric deficit, BCAAs become especially important.
Because you don't want the body to enter a catabolic state when you're not training, fasting, or training in a fasted state, adding in a good BCAA supplement can help safeguard you against the effects of muscle protein breakdown during times of reduced energy consumption.
When the body doesn't have enough energy reserves to draw on, it pulls from any stored resources.
Under normal circumstances, glycogen will always be the first to go, but when glycogen runs out, the body will need another fuel source.
Fat provides a high-energy substrate, but fat cannot be used towards MPS. As such, the body will go after existing muscle tissue to supply the required amino acids.
And while this can be the case, it's not guaranteed. It's unlikely to happen if you're consuming adequate amounts of dietary protein and your amino acid pool is full, but if you're not (and so many of us don't), you may be at risk of muscle breakdown.
When To Take BCAAs
The most optimal time to consume BCAAs is, of course, pre- or post-workout. Because resistance training causes micro-damage to muscles that require essential amino acids to repair, consuming your aminos before or after a workout guarantees immediate availability to start the repair process.
Research suggests that people ingesting BCAAs pre-workout may receive more benefits towards reducing DOMS and muscle damage.
In one specific study, 15 men were given BCAAs or a placebo before and after exercise, as well as the three days before exercise. Various markers of muscle damage were measured for the following four days 8.
Results showed that serum BCAA and 3HMB concentrations increased significantly in the pre-workout group immediately after the exercise, returning to baseline levels over the following days.
However, DOMS, upper arm circumference (CIR), and range of motion (ROM) were significantly improved in the pre-workout group.
Serum levels of creatine kinase (CK), lactate dehydrogenase (LDH), and aldolase were also significantly suppressed compared to the control group.
This study shows that BCAA supplementation before exercise may help attenuate DOMS and exercise-induced muscle damage (EIMD) caused by eccentric exercise than supplementation post-workout.
But what about on days you're not training?
Should You Take BCAAs On Rest Days?
The quick answer is yes.
Like we mentioned earlier, BCAAs play an important role in muscle repair and recovery, which means that their role on off-days comes into play through accelerating muscle repair to enable a faster, more efficient recovery.
Most people are aware of their role in increasing muscle mass, but they've also been implicated in limiting structural and metabolic alterations associated with exercise damage 9.
If DOMS and EIMD set in hard, the likelihood of you training the next day at your full potential is going to be significantly reduced. Chances are you'll actually be out from max performance for a few days.
But when you add a good BCAA supplement into the mix, you're giving that process a little kick.
Because the branched-chain amino acids are metabolized in skeletal muscle, as opposed to the liver like the other essential amino acids 10, BCAAs have been considered a potential nutritional strategy to avoid or at least ease exercise-induced muscle damage.
EIMD is primarily associated with mechanical strain and the resulting inflammatory processes, which means that reducing muscle protein breakdown during exercise and scavenging reactive oxygen species that cause the damage could alleviate some structural and metabolic alterations seen after EIMD 9.
Studies have looked at BCAA supplementation's effects on EIMD and DOMS through variations in frequency, amount, and duration, finding few positive outcomes with high frequency, high dose supplementation over a short duration.
Rather, a more extended supplementation period (>10 days) is necessary to receive the beneficial effects 9.
Authors concluded that BCAA supplementation taken prior (days to weeks) to strenuous exercise could help to mitigate skeletal muscle tissues alterations by enhancing mitochondrial biogenesis and reactive oxygen species (free radical) scavenging 11.
Taken together, there is ample research to support the benefits of BCAA supplementation on reducing EIMD and the onset of DOMS.
Still, as studies have noted, long-term supplementation at an appropriate dose is generally required to actually produce positive effects.
So, even if you're not training, taking your BCAAs will improve and accelerate your recovery, helping you get back into the gym faster and maximize your performance and results quicker.
- E Blomstrand, J Eliasson, HK Karlsson, R Köhnke. Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise. J Nutr. 2006;136(1 Suppl):269S-73S.
- MJ Drummond, BB Rasmussen. Leucine-enriched nutrients and the regulation of mammalian target of rapamycin signalling and human skeletal muscle protein synthesis. Curr Opin Clin Nutr Metab Care. 2008;11(3):222-226.
- BB Rasmussen, KD Tipton, SL Miller, SE Wolf, RR Wolfe. An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. J Appl Physiol (1985). 2000;88(2):386-392.
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