Am J Physiol Endocrinol Metab. 2004 Nov 23;
The combined ingestion of protein and free leucine with carbohydrate increases post-exercise muscle protein synthesis in vivo in male subjects.
Koopman R, Wagenmakers AJ, Manders RJ, Zorenc AH, Senden JM, Gorselink M, Keizer HA, van Loon LJ.
Department of Human Biology, Nutrition Research Institute Maastricht (NUTRIM Maastricht University, Maastricht, The Netherlands.
The present study was designed to determine post-exercise muscle protein synthesis and whole-body protein balance following the combined ingestion of carbohydrate with or without protein and/or free leucine. Eight male subjects were randomly assigned to 3 trials in which they consumed drinks containing either carbohydrate (CHO), carbohydrate and protein (CHO+PRO), or carbohydrate, protein and free leucine (CHO+PRO+leu) following 45 min of resistance exercise. A primed, continuous infusion of L-[ring-(13)C6]phenylalanine was applied, with blood samples and muscle biopsies collected to assess fractional synthetic rate (FSR) in the m. vastus lateralis as well as whole-body protein turnover during 6 h of post-exercise recovery. Plasma insulin response was higher in the CHO+PRO+leu compared to the CHO and CHO+PRO trials (+240+/-19% and +77+/-11%, respectively, P<0.05). Whole-body protein breakdown rates were lower, and whole-body protein synthesis rates were higher in the CHO+PRO and CHO+PRO+leu trials compared to the CHO trial (P<0.05). Addition of leucine in the CHO+PRO+leu trial resulted in a lower protein oxidation rate compared to the CHO+PRO trial. Protein balance was negative during recovery in the CHO trial, but positive in the CHO+PRO and CHO+PRO+leu trials. In the CHO+PRO+leu trial, whole-body net protein balance was significantly greater compared to values observed in the CHO+PRO and CHO trials (P<0.05). Mixed muscle FSR, measured over a 6h period of post-exercise recovery, was significantly greater in the CHO+PRO+leu trial compared to the CHO trial (0.095+/-0.006 %(.)h(-1) vs. 0.061+/-0.008 %(.)h(-1), respectively; P<0.05), with intermediate values observed in the CHO+PRO trial (0.0820 +/- 0.0104 %(.)h(-1)). We conclude that the co-ingestion of protein and leucine stimulates muscle protein synthesis and optimizes whole-body protein balance when compared to the intake of carbohydrate only.
From the full text:
Subjects received a beverage volume of 3 ml.kg-1 every 30 minutes to ensure a given dose of 0.3 g carbohydrate.kg-1 (50% as glucose and 50% as maltodextrin) and 0.2 g.kg-1 of a protein
hydrolysate [whey] every h, with or without the addition of 0.1 g.kg-1.h-1 leucine.
It really comes as no surprise that amino acids, especially leucine, can control metabolic signaling by acting as more than just nutrients. This is an excellent paper on the topic:
"The protein kinase mTOR is a common intermediate in both nutrient and hormone signal transduction pathways (Fig. 2). Signaling through mTOR is enhanced by nutrients and anabolic hormones, such as insulin or IGF-I [24,25], and repressed by elevation of cAMP [25-27] or activation of AMPK [28-30], suggesting that one function of mTOR is to integrate the anabolic response to nutrients and insulin and the catabolic response to counter-regulatory hormones, such as glucagon...Although other amino acids have been shown to increase signaling through mTOR, leucine is arguably the most potent of the amino acids in activating the pathway."
HMB is short for beta-hydroxy beta-methylbutyrate, and is a metabolite of leucine, one of the body�s essential amino acids. It one of the most popular body building supplements today, and when used in high enough volumes, very effective.
Can one use HMB instead of leucine and still see equally good or better results?
Also, do you believe the recommend dosage per your article of .1g per kg is adequate for BBers?