BCAA Basics Part 2
In Part I, we discussed the importance of leucine and that it is a trigger for MPS, but what can we do to maximize protein synthesis for the entire day, and extend the time in which our body is building or preserving muscle? A study performed by Gabriel Wilson and colleagues wanted to examine what could be done to extend protein synthesis throughout the day. The researchers wanted to examine whether a dose of leucine, carbohydrates, or leucine and carbohydrates would be able to overcome the decline in muscle protein synthesis that occurs 180 minutes after a protein rich meal.1 The rats followed a 20% protein, 50% carbohydrate, and 30% fat diet. After 7 days of this diet, they were deprived of food for 12 hours, given a 4 gram meal, and then 135 minutes after that meal, the rats were administered a 5mL oral dose of either 2.63g of carbs (half glucose, half sucrose), 270 mg of leucine, 2.63g of carbs and 270 mg of leucine, or water. The results showed that at 90 minutes, there was a peak in muscle protein synthesis, and with the water group, had returned to baseline. However, all three other groups were able to keep protein synthesis elevated at its peak or close to it. A combination of leucine and carbs, was slightly better at increasing protein synthesis than either carbs, or leucine alone, but not to a significant degree. 2
The above graph demonstrates the effect of leucine, carbs,
and leucine+carbs on MPS at 180 min when MPS seems to decrease.
From these results we come away with the knowledge that we can extend protein synthesis between meals, and prevent it from returning to baseline, leaving us in a muscle building state until our next meal. It’s interesting that carbohydrates kept protein synthesis elevated. Insulin is strong storage hormone, and forces glucose into muscle cells. This influx of glucose must be enough fuel for the muscle cell to keep the process going. Previous studies stated that once a certain level of leucine is reached, no more leucine will further increase muscle protein synthesis. So why is it that about two hours after ingestion of a leucine high meal, you can consume more leucine and extend the duration of this process? Leucine is also known to spike insulin levels. This may provide another way for the muscle cell to get fuel, as it seems to get exhausted with too much synthesis. In addition, the research also shows that carbohydrate consumption is not necessary, and does not further enhance muscle protein synthesis, and therefor recovery.
Leucine is critical in protein synthesis, and recovery, but what else can we do to enhance recovery, and improve performance? HMB. HMB (beta-hydroxy-beta-methylbuterate) is a metabolite of leucine. HMB may decrease breakdown, allowing you to put more stress on to your muscles, improve recovery, allowing you to perform more often and at a higher level, and it may enhance fat loss creating better body composition. However, we cannot simply ingest more leucine to get HMB. In order to get 3g of HMB (the recommended dose), we would need to ingest 60g of leucine which will equate to approximately 500g of protein.3 In order to get the optimal amount, supplementation is necessary.
A double-blind placebo controlled study conducted by Dr. Jacob Wilson and colleagues, examined the effect that 12 weeks of HMB had on 20 resistance trained men. The athletes were put on a diet formulated by a registered dietitian, consisting of 25% protein, 50% carbohydrates, and 25% fat. 3 day food records indicated that the diets consisted of 22% protein, 45% carbohydrates, and 33% fat with no difference between the two groups. The athletes were given 1g doses of either HMB or a placebo 30 minutes prior to exercise, at the mid-day, and evening meals. The exercise protocol consisted of three phases. Phase one was a 3 day per week undulating periodized resistance training program that lasted 8 weeks. Phase two was a 2 week overreaching cycle. This means that the athletes performed 5 days of training, as well as one day of power testing. Phase three consisted of two weeks of reduced training volume, as a form of active recovery. The HMB group was able to increase squat strength by 25% (vs 5% placebo), bench press strength by 12% (3% placebo), deadlift by 16% (9% placebo), and 18% for total strength (6% placebo), all of which were significantly greater when compared to the placebo. The Wingate test is a way to measure power output. The HMB supplemented group had a 18% increase in power compared to a 12% increase for the placebo. During the overreaching phase (phase two) the HMB group had almost no decrease in performance, while the placebo group had a significant decrease. The HMB group also had a significant decrease in body fat, and increase in body mass, while the placebo group had a slight drop in body fat.4
HMB is in its infancy when it comes to increasing performance, but these results are very promising. HMB has the ability to have athletes train extremely hard, without any real decrease in performance. This can lead to greater adaptation over time, and even more accrual of lean body mass, strength, and power. HMB also seemed to have a significant impact on weight loss and body composition. This is important to athletes because it can make them lighter, and they can have more functioning tissue (muscle) and perform to a higher degree.
Tune into Part 3!
References
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.
Wilson GJ, Layman DK, Moulton CJ, Norton LE, Anthony TG, Proud CG, Rupassara SI, Garlick PJ. Leucine or carbohydrate supplementation reduces AMPK and eEF2 phosphorylation and extends postprandial muscle protein synthesis and rats. Am J Physiol Endocrinol Metab. 2011 Dec;301(6):E1236-42.
Wilson GJ, Wilson JM, Manninen AH. Effects of beta-hydroxy-beta-methylbutyrate (HMB) on exercise performance and body composition across varying levels of age, sex, and training experience: A review. Nutr Metab (Lond). 2008;5:1.
Wilson JM, Lowery RP, Joy JM, et al. The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study. Eur J Appl Physiol. 2014;114(6):1217-27.
