From the article:
Myth: Glutamine is a great supplement for weight lifters.
Mythbuster: Tim Ziegenfuss
First, let me point out that I don't expect my take on glutamine to resonate with those who're convinced it's a worthwhile supplement.
I'll concede that glutamine is the most abundant free amino acid in the body, and has important roles in muscle tissue (as a nitrogen shuttle), the brain (as a component of cerebrospinal fluid), and the intestinal mucosa/immune cells (as an energy substrate). It's also cheap and pretty much tasteless, and supplement companies have worked hard to convince consumers that glutamine has anti-catabolic properties in humans.
But when you get right down to it, the most important role of glutamine for athletes is gut health. If you're an athlete competing in endurance-based sports, glutamine may help prevent upper-respiratory infections. If you simply slam the iron, a few grams of glutamine isn't going to do squat.
Put simply, I don't know of a single study in humans that shows glutamine has anabolic or anti-catabolic properties that increase training adaptations during resistance exercise. That includes a terrific study from Canada in which subjects were given 45 grams of glutamine per day during a six-week training program. Compared to the placebo group, subjects consuming glutamine had no greater increases in strength (measured via squat, bench press, and knee-extension torque), body composition (lean mass determined via DEXA), or muscle-protein breakdown (determined via urinary 3-methylhistidine excretion).
So ultimately, my take on glutamine and weight training is this: If you're into micromanaging things, glutamine probably won't hurt your efforts in the gym. But it almost certainly won't help.