You do resistance training and you want to build muscle, but you can’t be bothered with all those fiddly protein shakes. Why not just add 4 g leucine to a big glass of milk or yoghurt after your workout? 4 g is a big tablespoonful. Researchers at the University of Nottingham in England came to this conclusion after doing an experiment with 36 younger and older men.
The researchers got 9 young men, average age 24, to train their legs on a leg-extension machine. Afterwards they were given a protein drink containing 10 g milk protein and 24 g carbohydrates. A large 300 ml glass of milk or yoghurt contains the same amount of protein, but 10 g less carbs.
Another 9 men were given the protein drink but with 4.2 g leucine [Young Ex+SFO+Leu], and yet another 9 men were given 4.2 g alanine [Young Ex+SFO+Ala].
The researchers did the same with 19 older men, average age 70 [Old Ex+SFO+Leu] [Old Ex+SFO+Ala].
The researchers took samples of tissue from the subjects’ leg muscles on several occasions: before the men started training, and during the remainder of the day afterwards.
The figures below show that, after consuming the protein drink, the synthesis of muscle protein [FSR] increased in both the young and older subjects. When leucine was added to the protein drink, the increase was bigger.
The combination of strength training and protein drink boosted the amount of the anabolic signal molecule p70S6K11 in the subjectsâ€™ muscles. This increase was bigger in both young and old subjects when leucine was added to the protein drink.
“It would be a key next step to combine the anabolic influence of resistance exercise and ingestion of a amino acid source enriched with leucine over longer periods i.e. in order to determine if longer term supplements can increase clinically important aspects of muscle mass and muscle function in older individuals”, the researchers wrote.”
“Indeed, initial studies are in support of this notion, with one study showing that leucine enriched supplements show improvements indices of muscle mass and function. [J Am Geriatr Soc. 2012 Jan;60(1):16-23.] Perhaps our study highlights potential mechanisms underlying this.”
“In conclusion, this study shows that it is possible to enhance muscle protein synthesis and p70S6K1 responses in young and older men by giving leucine enriched suboptimal protein supplements immediately after exercise.”
Enriching a protein drink with leucine augments muscle protein synthesis after resistance exercise in young and older men
Maximizing anabolic responses to feeding and exercise is crucial for muscle maintenance and adaptation to exercise training. We hypothesized that enriching a protein drink with leucine would improve anabolic responses to resistance exercise (RE: 6 × 8 knee-extension repetitions at 75% of 1-RM) in both young and older adults. Groups (n = 9) of young (24 ± 6 y, BMI 23 ± 2 kg m?2) and older men (70 ± 5 y, BMI 25 ± 2 kg m?2) were randomized to either: (i) RE followed by Slim-Fast Optima (SFO 10 g PRO; 24 g CHO) with 4.2 g of leucine (LEU) or, (ii) RE + SFO with 4.2 g of alanine (ALA; isonitrogenous control). Muscle biopsies were taken before, immediately after, and 1, 2 and 4 h after RE and feeding. Muscle protein synthesis (MPS) was measured by incorporation of [1, 2–13C2] leucine into myofibrillar proteins and the phosphorylation of p70S6K1 by immunoblotting. In young men, both area under the curve (AUC; FSR 0–4 h P < 0.05) and peak FSR (0.11 vs. 0.08%.h.?1; P < 0.05) were greater in the SFO + LEU than in the SFO + ALA group, after RE. Similarly, in older men, AUC analysis revealed that post-exercise anabolic responses were greater in the SFO + LEU than SFO + ALA group, after RE (AUC; FSR 0–4 h P < 0.05). Irrespective of age, increases in p70S6K1 phosphorylation were evident in response to both SFO + LEU and SFO + ALA, although greater with leucine supplementation than alanine (fold-change 2.2 vs. 3.2; P < 0.05), specifically in the older men. We conclude that addition of Leucine to a sub-maximal PRO bolus improves anabolic responses to RE in young and older men.