GLOSSARY

Negative Nitrogen Balance occurs when nitrogen losses exceed input over the assessment period. It can indicate bodily protein loss without identifying the cause by itself.

An underfed high-training athlete may need energy and protein adjusted, not one amino acid alone. Soreness does not diagnose negative balance. Duration, health, intake and losses belong together in assessment.

Nitrogen balance compares nitrogen inputs and outputs over a specified period. Urine is not the only loss: faeces, skin and sweat contribute, sometimes through estimates. Incomplete food or loss records can shift the result. It does not directly measure muscle mass or establish adequacy of every other nutrient in the person's diet.

Amino-acid nitrogen is transferred, reused or excreted; some becomes urea in the liver and is eliminated through the kidneys. The carbon skeleton has separate metabolic fates. This normal process alone does not diagnose kidney injury, although established kidney disease requires an individually appropriate dietary protein plan rather than automatic use of sport targets.