Title: Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise.
Researchers: Tipton KD, Rasmussen BB, Miller SL, Wolf SE, Owens-Stovall SK, Petrini BE, & Wolfe RR.
Source: American Journal of Physiology Endocrinology & Metabolism. 2001 Aug;281(2):E197-206.
Summary: This study was designed to determine whether drinking an essential amino acid-carbohydrate supplement (6gEAA+35g carbs) before exercise results in a greater anabolic response than supplementation after resistance exercise.
Methods: Six healthy human subjects participated in two trials in random order, PRE (6g EAA+35g carbs consumed immediately before exercise), and POST (6g EAA+35g carbs consumed immediately after exercise). A primed, continuous infusion of L-[ring-(2)H(5)]phenylalanine, femoral arteriovenous catheterization, and muscle biopsies from the vastus lateralis were used to determine phenylalanine concentrations, enrichments, and net uptake across the leg.
Results: Blood and muscle phenylalanine concentrations were increased by approximately 130% after drink consumption in both trials. Amino acid delivery to the leg was increased during exercise and remained elevated for the 2 h after exercise in both trials.
Delivery of amino acids (amino acid concentration times blood flow) was significantly greater in PRE than in POST during the exercise bout and in the 1st h after exercise. Total net phenylalanine uptake across the leg was greater during PRE (209 +/- 42 mg) than during POST (81 +/- 19).
Phenylalanine disappearance rate, an indicator of muscle protein synthesis from blood amino acids, increased after EAC consumption in both trials.
Conclusion: These results indicate that the response of net muscle protein synthesis to consumption of an EAC solution immediately before resistance exercise is greater than that when the solution is consumed after exercise, primarily because of an increase in muscle protein synthesis as a result of increased delivery of amino acids to the leg.
Discussion: First let's talk about what's right with this study. Then we'll tackle what's wrong with it to keep things in perspective.
Here's what they did right. These researchers measured systemic levels of amino acids after the drink, the amount of amino acids delivered to muscle tissue, as well as the uptake of amino acids into the muscle for protein synthesis.
This way they were able to follow the effects of the protein drink from the time it entered the blood stream to its eventual incorporation into muscle protein.
What they found was that systemic (amino acids in the blood stream) levels of amino acids were the same whether you took the drink before or after training.
Amino acid delivery to the leg increased during exercise, and remained elevated for at least 2 hours after training. This is the result of increased blood flow to the working muscle. This increase in blood flow peaks during exercise then returns to normal over the next 2 hours.
Here is where it gets interesting. Delivery of amino acids, meaning the quantity of amino acids delivered to the muscle, was significantly greater when they gave the protein drink before training and remained significantly higher for at least an hour after the workout, compared to drinking it immediately after training.
The increased delivery of amino acids from drinking the protein drink before training increased amino acid uptake into muscle by over 250%!
The superiority of taking protein before training is obvious when comparing the percentage of amino acids taken up by the leg from the protein drink. When the protein drink was taken before training, ~42% of the amino acids in the drink were taken up into the muscle.
The proportion was much lower when the protein was drank after training, only about 16% of the drink was taken up into the muscle. That's over twice as much of the amino acids being taken up by muscle when it is consumed before training. It was estimated that ~86% of total uptake was incorporated into proteins whereas only ~48% of total uptake during the post workout trail was incorporated into proteins. That's a huge difference.
As for the bad, this study only used 6 grams of amino acids! I can blow my nose and produce more than 6 grams of protein. These researchers had previously (1) used higher amounts of protein (40 grams) without carbs, so in this study they wanted to see if they could elicit a similar anabolic response with less protein and more carbs.
Of course, anybody who's serious about putting on muscle weight is going to need more than 6 grams of amino acids before their workout. I would suggest at least 20 grams before and another 20 grams after.
Although they used only essential amino acids in this study, using a whole protein source is equally effective as long as it contains all the essential amino acids.
If you want the most muscle growth from your protein supplements, you must take one right before training, and the another right after.
- Tipton, KD, Ferrando AA, Phillips SM, Doyle D, Jr, and Wolfe RR. Postexercise net protein synthesis in human muscle from orally administered amino acids. Am J Physiol Endocrinol Metab 276: E628-E634, 1999