Why oral glutamine barely moves the muscle pool
Glutamine is the most abundant free amino acid in the body, and healthy people already maintain large plasma and intramuscular pools. The body also synthesizes it readily, so a swallowed dose is largely taken up by the gut and immune cells before it can meaningfully raise the concentration inside skeletal muscle. The system is buffered against the change supplements aim to create.
This is the core reason glutamine underdelivers as a muscle-building aid in well-fed, healthy trainees.
What controlled trials actually found
Randomized studies in healthy resistance-trained people have generally shown no meaningful advantage over placebo for muscle mass, strength, or recovery. The original interest came from clinical settings of severe stress where glutamine pools genuinely fall, a very different context from a healthy lifter.
This is general educational information, not medical advice. Findings differ between healthy and clinically stressed populations. Consult a qualified professional before use, particularly if you have a medical condition.