BCAAs (branched chain amino acids) include leucine, isoleucine, and valine. These are three of the nine essential amino acids (EAAs), meaning our body cannot synthesize them, so we must consume them in our diet. BCAAs are present in complete protein sources such as animal proteins (eggs, dairy, poultry, meat, fish) and soy. BCAAs are unique in that they are the only ones that the muscle can actually take up directly and oxidize for energy. However, in prolonged endurance exercise (more than 90 minutes), the amount of BCAA oxidation is still very small compared to carbohydrate and fat. BCAAs are also important in triggering the anabolic process of muscle protein synthesis (MPS), although leucine appears to be the main driver for this of the three BCAAs.
Like all amino acids, BCAAs flux in and out of the body’s amino acid pool and are used in the body as needed. Provided an athlete is ingesting adequate protein through the diet (at least ~1.2 g/kg-day) and eating high-quality proteins that provide all EAAs, there should be a sufficient amount of BCAAs available in the AA pool for to the body for use when needed.
In theory, supplementing with BCAA during endurance efforts could boost BCAA oxidation and delay fatigue, thereby improving performance or exercise capacity. However, there is no evidence base to suggest BCAA supplementation actually improves performance. Now, if an athlete was not able to regularly meet protein needs through the regular diet alone, it is possible that supplementing during exercise could be of benefit.
Regarding MPS and recovery, leucine is the primary driver of the anabolic response. Likewise, if the athlete is ingesting sufficient protein in his/her regular diet with adequate leucine, BCAA supplementation is likely not necessary. Research examining the effect of BCAA supplementation compared to placebos does show elevated markers with respect to MPS response, but when compared to a complete protein like whey, BCAAs are not better.
Taking all this into consideration, you are probably better off trying to hit your daily protein target (1.2-1.8 g/kg-day), choosing complete protein sources and complementary plant protein sources as often as possible. Both quantity and quality matter! However, if you feel like BCAAs help your performance, then the psychological edge is worth it.
If you regularly fall short on your protein intake, whether or not you are vegan, it would be worth trying supplementation with whey (or BCAAs if you can't have whey), although the best approach is always to eat a whole food diet that provides your daily nutrient requirements.
There may be days when you do very long rides and it’s just not possible timing wise to ingest all your daily protein. In this case, you could use a BCAA supplement during the ride and then ingest a high-quality (i.e., whey) recovery drink and meal post ride.
The recommended dose of BCAAs would provide somewhere between 1.7-3.5 g leucine. For reference, 20-25 grams of whey protein would also provide the recommended amount of leucine.
About the Author
Dr. Namrita Brooke began her coaching practice while a doctoral student. Today she is a full time coach and nutritionist, and she runs an online group program called Fueling Fat Loss. She is also a cycling coach and the head nutritionist with Velocious Cycling Adventures. Her personal athletic experience ranges from endurance mountain biking to off-road triathlon, cross-country mountain bike racing, running, road cycling, duathlon, and cyclocross. Her research background includes hydration and sports drink research, and the interaction of nutrition, physical activity, and the brain.