Essentials of Nutrition for Sports

Branch-Chain Amino Acids, Arginine, Glutamine

The claim, popular in the late 1990s: Branch-chain amino acids

improve performance by affecting serotonin, a brain hormone.

The evidence: Not convincing. Just the opposite. For example of

six reported studies in 1998, no effect was noted. For example, Foster et al

32 found no effect on serotonin, glucose, or lactate. There

was no change in performance.

Arginine may stimulate the release of hormones including

growth hormone and insulin. Glutamine may be a preferred fuel source for cells that line the gastro

intestinal tract. Pharmacological

dosing of these two amino acids is much higher than the amounts contained in an Endurox serving. The roles of these two amino acids as ergogenic agents are uncertain.

For a more complete review of

proteins and amino acids, read

the basic science section about protein beginning on page

56

, the

amino acid section on page

62

, and the section on athletic

considerations on page

63

.

Remember: Amino acid supplements are not innocuous; they

may be harmful. Carbohydrate/Protein 4:1 Supplementation

The hype about protein for recovery began when Zawadski, in

1995, showed that added protein helps restore glycogen.

Subsequent research has show

n that protein helps when

carbohydrate intake is inadequate

. When and if protein helps,

additional carbohydrate helps even more.

The graph shown on the Endurox R4 manufacturer’s website,

Figure 19

, from a study by van Loon,

33 demonstrating the value of

32 Foster, C., Faria, E., Chinevere, T., & Faria, I. (1

998). Effect of branched-chain amino acid ingestion on

moderate and high intensi

ty cycling. Medicine and Science in Sports and Exercise, 30(5), Su

pplement

abstract 92. View online at http://www-rohan.sdsu.edu/dept/coachsci/csa/vol53/foster.htm. Accessed 11-15-2004.

protein for glycogen resynthesis is politely and charitably best described as deceptive.

Why is

Figure 19

deceptive? Because it implies that protein is

important in recovery. In the van Loon study quoted, when one-quarter again as many protein calories were added to a carbohydrate recovery drink, glycogen synthesis almost doubled.

Figure 19. Glycogen synthesis is almost doubled when one-quarter again as many protein calories are added to a carbohydrate recovery drink. If you are impressed, look immediately below at

Figure 20

.

What the figure used by manufacturer did not show was what

happened when just carbohydrate was used. Instead of adding one-quarter again as many protein calories, if one-quarter again as many carbohydrate calories were added, glycogen synthesis almost tripled.

When calories ingested were equivalent, carbohydrate was

superior to a combination of carbohydrate and protein.

This is shown in the full figure,

Figure 20

.

33 Van Loon, L.J.C., et al. (2000). Maximizing postexercise muscle glycogen synthesis: carbohydrate

supplementation and the application of amino acid or protein hydrolysates mixtures. The American Journal of Clinical Nutrition. 72(106).

Nutrition for Sports, Essentials of 156