Last week after finishing up my posts about exercise-induced hormones I fully intended on digging deeper into the importance of carbohydrates, specifically simple carbohydrates surrounding training. While I certainly will be doing this research soon, this week I’d like to look at branched-chain amino acids (BCAAs) and their role in muscle-protein synthesis, around training specifically. This topic came up from a reader last week who questioned the role of BCAAs consumed during exercise and whether or not it really does aid in muscle-protein synthesis or not. It was actually a pretty good question given all the information we learned about exercise-induced hormones the last two weeks.
Before we get started I’d like to say if there are ever any topics you’d like to me research regarding training and nutrition please feel free to comment and let me know and I’d be more than happy to look into it. It may not necessarily warrant an entire article like in this case but I’ll certainly look into it and get back you. If it takes an article I’m more than happy to do that too. With that said, let’s kick back, relax and take a look at the role of BCAAs for muscle-protein synthesis surrounding training.
BCAAs are essential amino acids that can be oxidized in skeletal muscle. It is known that exercise promotes degradation of BCAAs. One thing that has been shown over and over is that BCAAs are anti-catabolic. This is one reason why you hear about utilizing BCAAs during training when on a fat loss diet when you are in a caloric deficit. Since the acute effects of exercise are catabolic, the thought process behind utilizing BCAAs with training seems to make sense. Exercise requires a sequence of metabolic adjustments from the catabolic period of exercise to the anabolic period of recovery and BCAAs can help aid in both periods.
We know that BCAAs are anti-catabolic, but what is less clear is how much they help in muscle-protein synthesis and in turn anabolism during exercise when muscle building in a priority. The key word there is during exercise. Numerous studies have shown that BCAAs, especially leucine, have a stimulatory effect on protein synthesis in the recovery period after exercise. One study done on human subjects supplementing with BCAAs during and after one session of quadriceps muscle resistance exercise showed that BCAAs activate mTOR and p70 S6 kinase in human muscle in the recovery period after exercise. This is great for showing the importance of recovering with BCAAs but the study didn’t show the difference between supplementing during and after, since it did both we don’t know if the intra-workout supplementation did anything or if the post-workout was enough on its own.
In all my research I was unable to find anything that clearly showed consuming BCAAs during exercise had a positive effect on muscle-protein synthesis. In one study consumption of BCAAs did not significantly effect the next exchange of aromatic amino acids in the exercising muscle during exercise. Researchers said, however, that things like the rate of release of phenylalanine and tyrosine are so variable that it makes it tough to conclude the effect during exercise. This was a common theme I found for anything that researched intra-workout BCAA consumption in regards to muscle-protein synthesis. They always went back to saying there were too many variables to make any conclusions. If the act of exercise is catabolic, is it really possible to increase protein synthesis during this period by supplementing with BCAAs? I’d say I doubt it, but that doesn’t mean there aren’t benefits either.
Studies do show that BCAA supplementation before and after exercise has beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis. While it’s not fully known if BCAAs taken during exercise increase protein synthesis I think it’s safe to say it’s not going to hurt and their anti-catabolic effects warrant some thought. It’s of my opinion, however, that if you are consuming BCAAs either in the form of a straight BCAA supplement or by getting them from whey protein, which is rich in BCAAs, before and after your workout, then that will be all you need to increase protein synthesis as well as assist in minimizing the breakdown of protein from exercise. If you feel intra-workout BCAAs help, even if just for something like a lower rate of perceived exertion, then by all means use them all you want.
On top of increasing protein synthesis BCAAs have been shown to maximize fat loss, improve exercise efficiency by reducing fatigue due to heightened aerobic and anaerobic capacity, improve testosterone levels, reduce cortisol levels and improve strength. So while we don’t know about intra-workout BCAAs and protein synthesis for certain, the fact remains that research shows consumption around training helps maximize muscle mass by either helping increase muscle-protein synthesis or decrease muscle-protein degradation. You really can’t go wrong with BCAAs, intra-workout or not.