Hi Chris,

Bodybuilders have long used insulin as a training/recovery tool (drug). Have
you considered a possible additive effect of amino acids to the insulin
response from carbohydrate to enhance recovery? I'm still new to the area of
hormones but I'm finding some research that might have been overlooked by
the low-carb diet gurus showing insulin responses to amino acids too.

When 30 g of glucose is orally administered, there is a 550% increase in the
overall rate of insulin secretion (Porksen et al, 1996). With a similar does
of an amino acid mixture (0.35g/kg body weight, or ~30g for an 80kg athlete)
there is a similar effect (533% increase in total insulin) (Knerr et al,
2003; Gröschl et al, 2003). As far as I can tell, amino acids and glucose
produce similar insulin effects.

We get an insulin response to amino acids because insulin is a storage
hormone. Most people are most familiar with its properties for storing
carbohydrate, but it also stores protein. Insulin plays a key role in
increasing protein synthesis (Rennie, 2001; Tipton and Wolfe, 2001; Biolo et
al, 1999; Fryburg et al 1995), inhibits proteolysis (muscle breakdown)
(Fryburg et al 1995), and muscle hypertrophy (Tipton and Wolfe, 2001),
especially after resistance training (Fluckey et al, 1996a; Fluckey et al,
1996b). Resistance exercise can even stimulate insulin secretion (Fluckey et
al, 1995). Even if we stimulate insulin secretion with carbohydrate feeding
we can still get protein synthesis (Welle et al, 1989), assuming adequate
amino acids are present.

Amino acids stimulating insulin production is somewhat non-intuitive, but
from a functional perspective it makes sense. If you want to keep the amino
acids, you need to store them. So maybe protein/amino acid supplements
benefit exercise training by adding to the carbohydrate-induced insulin
response. Any feedback anybody has on this would be greatly appreciated.

Cheers,
Eric

__________________________________
Eric Drinkwater, MPE
Ph.D. Scholar, Victoria University
Department of Physiology
Australian Institute of Sport
PO Box 176
Belconnen ACT
Australia
2616
Phone +61 2 6214 7887
Fax +61 2 6214 1904
eric.drinkwater@...

References:

Biolo G, Williams BD, Fleming RY, Wolfe RR. Insulin action on muscle protein
kinetics and amino acid transport during recovery after resistance exercise.
Diabetes. 1999 May; 48(5): 949-57.

Fluckey JD, Kraemer WJ, Farrell PA. Pancreatic islet insulin secretion is
increased after resistance exercise in rats. J Appl Physiol. 1995 Oct;
79(4): 1100-5.

Fluckey JD, Vary TC, Jefferson LS, Evans WJ, Farrell PA. Insulin stimulation
of protein synthesis in rat skeletal muscle following resistance exercise is
maintained with advancing age. J Gerontol A Biol Sci Med Sci. 1996a Sep;
51(5): B323-30.

Fluckey JD, Vary TC, Jefferson LS, Farrell PA. Augmented insulin action on
rates of protein synthesis after resistance exercise in rats. Am J Physiol.
1996 Feb; 270(2 Pt 1): E313-9.

Fryburg DA, Jahn LA, Hill SA, Oliveras DM, Barrett EJ. Insulin and
insulin-like growth factor-I enhance human skeletal muscle protein anabolism
during hyperaminoacidemia by different mechanisms. J Clin Invest. 1995 Oct;
96(4): 1722-9.

Gröschl M, Knerr I, Topf H-G, Schmid P, Rascher, W and Rauh, M. Endocrine
responses to the oral ingestion of a physiological dose of essential amino
acids in humans. J Endocrinol. 2003 Nov; 179(2): 237-44.

Knerr I, Groschl M, Rascher W, Rauh M. Endocrine effects of food intake:
insulin, ghrelin, and leptin responses to a single bolus of essential amino
acids in humans. Ann Nutr Metab. 2003; 47(6): 312-8.

Porksen N, Munn S, Steers J, Veldhuis JD, Butler PC. Effects of glucose
ingestion versus infusion on pulsatile insulin secretion. The incretin
effect is achieved by amplification of insulin secretory burst mass.
Diabetes. 1996 Oct; 45(10): 1317-23.

Rennie MJ. Control of muscle protein synthesis as a result of contractile
activity and amino acid availability: implications for protein requirements.
Int J Sport Nutr Exerc Metab. 2001 Dec; 11 Suppl: S170-6.

Tipton KD, Wolfe RR. Exercise, protein metabolism, and muscle growth. Int J
Sport Nutr Exerc Metab. 2001 Mar; 11(1): 109-32.

Welle S, Matthews DE, Campbell RG, Nair KS. Stimulation of protein turnover
by carbohydrate overfeeding in men. Am J Physiol. 1989 Sep; 257(3 Pt 1):
E413-7.

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