McMaster’s University is home to some of the leading protein researchers. Since Leucine is the hottest amino acid you can bet they are going to put it to the test.
This time they took several formulations and gave them to men right after training (one leg extensions). They took muscle biopsies from both the trained leg and the rested leg right after the last training set, 1.5 hours, and 4.5 hours later. They split these 40 guys into 5 groups and gave them the following immediately after the leg extensions:
- 6 grams of whey protein (including .75 grams of Leucine) (W6 Group)
- 6 grams of whey protein, with 2.25 grams of Leucine (or 3 grams of total Leucine) (W6 + Low LEU)
- 25 grams of whey protein (including 3 grams of Leucine) (W25)
- 6 grams of whey protein, with 4.25 grams of Leucine, 1 gram of isoleucine, and 1 gram of valine added (5 grams of Leucine total) (W6+BCAA)
- 6 grams of whey protein, with 4.25 grams of Leucine, 1 gram of alanine, and 1 gram of glycine added (5 grams of Leucine total) (W6+High LEU)
All five drinks contained carbs and fats but were equal in calories (241). Interestingly they also gave them prepackaged meals for the two days prior to testing including 1.2 grams of protein per kilogram of body weight, which ensures a greater consistency in terms of protein response on the testing day. Other findings included:
Insulin response to all 5 drinks was similar
- For plasma aminos, area under the curve (AUC) for leucine was greatest in the 5th group (6 grams of protein plus leucine)
- Time to max concentrations was greatest in the 4th group (6 grams protein plus BCAA’s), but occurred first in the Protein plus high leucine group (5th group)
- Intracellular leucine was greatest in the 5th group at 1.5 hours, and 4.5 hours (which was just slightly above baseline)
- Overall maximum protein synthesis was greatest in the 25 gram whey protein group (267%) and the low protein, high leucine group (group 5)was slightly behind at 220%. Meaning both were better than even group 4 with added BCAA’s.
The authors of this study conclude:
Our results showed that the addition of a higher dose of leucine to a smaller amount of protein (6.25 g) within a mixed macro- nutrient beverage enhanced MPS to the same level as that seen with 4 times as much whey protein (25 g).
Now perhaps the most interesting part of this study other than low protein, high leucine working just as well as 25 grams of whey protein is that the low protein, high leucine group with added glycine and alanine performed better than the low protein, high leucine with added BCAA’s. Meaning that perhaps all this controversy over “spiked” protein with added glycine and taurine really isn’t as bad as we thought. That’s of course assuming each scoop has an adequate leucine dose. Do you think supplement companies did this on purpose?? I would not be surprised to see them claim they did now that they have some scientific support. SIGH
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