Acute glutamine ingestion modulates lymphocytic responses to exhaustive exercise in the heat

The purpose of this study was to determine if acute intake of glutamine modulates homeostatic, hematologic, immune, and inflammatory responses to exhaustive exercise in the heat. Thirteen healthy, untrained young men participated in this randomized, double-blind, placebo-controlled, crossover study. They served as their own control and completed 2 trials of treadmill exercise at 40% maximal oxygen uptake to exhaustion in a hot environment (temperature, 38.0 ± 1.0 °C; relative humidity, 60.0% ± 5.0%; oxygen, 20.8%) following placebo (PLA) and glutamine (GLN) consumption. Heart rate, gastrointestinal temperature, forehead temperature, the rating of perceived exertion, and body weight were measured. Blood samples were collected before and after exercise. After exhaustive exercise in the heat (PLA vs. GLN: 42.0 ± 9.5 vs. 39.6 ± 7.8 min, p > 0.05), significant changes in homeostatic, hematologic, and immune parameters (elevated natural killer (NK) cells and neutrophils, and reduced CD4+/CD8+ ratio and CD19+ ly...