2 Studies that might be of interest. Of course, would be nice to get a more of an analysis. The full papers are available in the links.

http://ajpendo.physiology.org/cgi/content/full/288/4/E761
http://jcem.endojournals.org/cgi/content/f...625798f5a0562d9

Exogenous amino acids stimulate human muscle anabolism without interfering with the response to mixed meal ingestion -- Paddon-Jones et al. 288 (4): E761 -- AJP - Endocrinology and Metabolism

Quote:
Exogenous amino acids stimulate human muscle anabolism without interfering with the response to mixed meal ingestion

Douglas Paddon-Jones,1,3 Melinda Sheffield-Moore,1,3 Asle Aarsland,1,2,3 Robert R. Wolfe,1,2,3 and Arny A. Ferrando1,3 Departments of 1Surgery and 2Anesthesiology, The University of Texas Medical Branch, and 3Shriners Hospitals for Children, Galveston, Texas
Submitted 2 July 2004 ; accepted in final form 29 November 2004

We sought to determine whether ingestion of a between-meal supplement containing 30 g of carbohydrate and 15 g of essential amino acids (CAA) altered the metabolic response to a nutritionally mixed meal in healthy, recreationally active male volunteers. A control group (CON; n = 6, 38 ± 8 yr, 86 ± 10 kg, 179 ± 3 cm) received a liquid mixed meal [protein, 23.4 ± 1.0 g (essential amino acids, 14.7 ± 0.7 g); carbohydrate, 126.6 ± 4.0 g; fat, 30.3 ± 2.8 g] every 5 h (0830, 1330, 1830). The experimental group (SUP; n = 7, 36 ± 10 yr, 87 ± 12 kg, 180 ± 3 cm) consumed the same meals but, in addition, were given CAA supplements (1100, 1600, 2100). Net phenylalanine balance (NB) and fractional synthetic rate (FSR) were calculated during a 16-h primed constant infusion of L-[ring-2H5]phenylalanine. Ingestion of a combination of CAA supplements and meals resulted in a greater mixed muscle FSR than ingestion of the meals alone (SUP, 0.099 ± 0.008; CON, 0.076 ± 0.005%/h; P < 0.05). Both groups experienced an improvement in NB after the morning (SUP, –2.2 ± 3.3; CON, –1.5 ± 3.5 nmol·min–1·100 ml leg volume–1) and evening meals (SUP, –9.7 ± 4.3; CON, –6.7 ± 4.1 nmol·min–1·100 ml leg volume–1). NB after CAA ingestion was significantly greater than after the meals, with values of 40.2 ± 8.5 nmol·min–1·100 ml leg volume–1. These data indicate that CAA supplementation produces a greater anabolic effect than ingestion of intact protein but does not interfere with the normal metabolic response to a meal.
Essential Amino Acid and Carbohydrate Supplementation Ameliorates Muscle Protein Loss in Humans during 28 Days Bedrest -- Paddon-Jones et al. 89 (9): 4351 -- Journal of Clinical Endocrinology & Metabolism

Quote:
Essential amino acid and carbohydrate supplementation ameliorates muscle protein loss in humans during 28 days bedrest.

Paddon-Jones D, Sheffield-Moore M, Urban RJ, Sanford AP, Aarsland A, Wolfe RR, Ferrando AA.Collaborators (1)Wolfe RR.
Metabolism Unit, 815 Market Street, Galveston, Texas 77550, USA. djpaddon@utmb.edu

We determined whether essential amino acid and carbohydrate supplementation could offset the catabolic response to prolonged inactivity. Major outcome measures included mixed muscle fractional synthetic rate (FSR), phenylalanine net balance, lean leg mass, and leg extension strength. On d 1 and 28, vastus lateralis muscle biopsies and femoral arterio-venous blood samples were obtained during a primed constant infusion of l-[ring-(2)H(5)]phenylalanine. Net balance and FSR were calculated over 16 h, during which the control group (CON) received a nutritionally mixed meal every 5 h (0830, 1330, and 1830 h). The experimental group (EXP) also consumed 16.5 g essential amino acids and 30 g carbohydrate (1100, 1600, and 2100 h). The dietary regimen was maintained during bedrest. FSR was higher in the EXP group on d 1 (EXP, 0.099 +/- 0.008%/h; CON: 0.075 +/- 0.005%/h) and d 28 (EXP, 0.093 +/- 0.006%/h; CON, 0.055 +/- 0.007%/h). Lean leg mass was maintained throughout bedrest in the EXP group (+0.2 +/- 0.3 kg), but fell in the CON group (-0.4 +/- 0.1 kg). Strength loss was more pronounced in the CON group (EXP, -8.8 +/- 1.4 kg; CON, -17.8 +/- 4.4 kg). Essential amino acid and carbohydrate supplementation may represent a viable intervention for individuals at risk of sarcopenia due to immobility or prolonged bedrest.
Even though calorie intake was a confound in the 1st study, looking at the individual response to a meal vs. EAA and glucose supplement, the EAA appears to provide a much greater increase in muscle protein synthesis.

translate to a measurable change in muscle mass over a period of weeks or months, recent data from our laboratory suggest that there is indeed a correlation between acute stimulation of muscle protein synthesis and chronic changes in muscle mass (27, 33). In a recent study in which subjects were provided with an EAA supplement three times a day for 28 days during bed rest, the repeated acute stimulation of muscle protein synthesis provided by the CAA supplement on day 1 of bed rest resulted in a predicted net gain of 7.5 g of muscle over a 24-h period (27). When extrapolated over the entire 28-day study, the predicted change in muscle mass corresponded to the actual change in muscle mass (210 g) measured by dual-energy X-ray absorptiometry. Although it may be tempting to speculate that such a supplement regimen would enable sedentary individuals to increase muscle mass without any accompanying physical activity, it must be noted that the estimated change in muscle mass was small (7.5 g/day) and may not represent a linear and/or continuous increase in muscle mass for extended periods greater than a month.

In conclusion, ingestion of a CAA supplement produces a greater anabolic effect than ingestion of a nutritionally mixed meal, despite similar EAA content. Furthermore, ingestion of the CAA supplement does not result in a subsequent compensatory nadir in net phenylalanine balance and does not effect the normal anabolic response to ingestion of a nutritionally mixed meal.