BCAA Basics Part 1
Protein is what our muscle cells are made of. Protein is essential in recovery, growth, and even energy production of muscle tissue. Many athletes and fitness enthusiasts look to protein to improve their athletic performance. Not only can protein benefit athletic performance, but it can also improve body composition, increase or maintain muscle mass, and keep these athletes healthy past their athletic careers. For many athletes, it is extremely difficult to gage how much protein they really need to add to their diet. It can come in supplemental form or it may come with an increase of whole food proteins. Athletes in the past just reached for a protein shake, and thought that that was that. Protein may work in boosting performance, but it will not be optimized if the proper protocols are not followed. Increasing athletic performance is not as simply as increasing protein in the athlete’s diet. Protein quality, the amount, and timing of the protein intake, are all crucial in creating an environment in the body that is able to perform well, recover efficiently, and grow in size. Many studies examine body composition, which can improve performance as well since there is more functioning tissue in the body, and less overall weight. Recommendations on protein intake related to quantity, quality, and timing will be suggested based on the current scientific research. Athletic performance is improved with the use of leucine, timing of optimal leucine intake, HMB, and simply increasing protein won’t have a significant effect on performance.
Before continuing, the athlete needs to understand what leucine is. Leucine is an essential amino acid, one of three branched chain amino acids. It alone is responsible for stimulating muscle protein synthesis, which will stop the negative protein balance or breakdown of protein that occurs from resistance training, and flip it so that you are in a positive balance, and able to increase muscle size and strength. 1 A study conducted by Dr. Layne Norton and colleagues found that leucine was responsible for the strongest activation of muscle protein synthesis, however, the length of this spike in protein synthesis did not correlate with the amount of leucine. The study used male rats, and fed them for 5 days with a diet consisting of 20% protein (whey protein), 50% carbohydrates, and 30% fats. The rats were then starved for 12 hours, fed a 4 gram meal that was rich in leucine, and then plasma and skeletal muscle samples were taken at 45, 90, 135, 180, and 300 minutes after consumption. The results indicated that muscle protein synthesis was highest between 45 and 90 min, and returned to baseline at 180 minute
These two graphs illustrate how leucine may be linked to MPS (muscle protein synthesis).
The second part of the study examined two
different protein sources. Whey protein, which is very high in leucine (10.6%), and wheat protein, which contains a lower amount of leucine (6.8%). The rats were fed a similar feeding protocol for 5 days except that the diet consisted of 14% protein, 56% carbohydrates, and 30% fats. The rats were starved for 12 hours, and then fed a 4 gram meal consisting of one of the following: 10% wheat protein, 10% whey protein, 20% wheat protein, 20% whey protein, 30% wheat protein, or 30% whey protein. Plasma and skeletal muscle samples were taken 90 minutes after consumption. Why at 90 minutes, because the first part of the experiment determined that 90 minutes was when muscle protein synthesis was at its highest activation. The results showed that all of the whey protein groups (10%, 20%, and 30%) were able to stimulate protein synthesis, and only the 20% and 30% wheat groups were able to initiate protein synthesis. In addition, leucine concentrations were higher in all of the whey groups, except the 30% group. This is an indication that 30% wheat was substantial enough to peak muscle protein synthesis.2
What does this research tell us? Leucine is the trigger for muscle growth, and muscle preservation, but it is not the determinant for how long this increase in protein synthesis lasts. There seems to be a threshold level that once hit, muscle protein synthesis can no longer be increased. Leucine was also a clear indicator of protein quality based on the second part of the experiment. The higher the leucine content was, the better the protein synthesis response. Protein quality is crucially important. The higher the quality of protein, the less overall protein (and therefore calories) are consumed leading to better body composition, and muscle is preserved better, because protein balance is now positive and not negative.
Tune into Part 2 for more!
References
Layman DK, Norton LE. Leucine Regulates Translation Initiation of Protein Synthesis in Skeletal Muscle after Exercise. J. Nutr. 136: 533S–S537, 2006
Norton LE, Layman DK, Bunpo P, Anthony TG, Brana DV, Garlick PJ. The leucine content of a complete meal directs peak activation but not duration of skeletal muscle protein synthesis and Mammalian target of rapamycin signaling in rats. J Nutr. 2009 Jun;139(6):1103-9.
