EFFECT OF GLUTAMINE SUPPLEMENTATION ON CHANGES IN THE IMMUNE-SYSTEM INDUCED BY REPEATED EXERCISE

The ability of lymphocytes to proliferate and generate lymphokine acti vated killer (LAK) cell activity in vitro is dependent on glutamine. I n relation to intense exercise the lymphocyte concentration, the proli ferative response, the natural killer and LAK cell activity, and the p lasma glutamine concentration decline. It has been hypothesized that i n relation to physical activity a lack of glutamine may temporarily af fect the function of the immune system. Purpose: The purpose of this s tudy was to examine the influence of glutamine supplementation on exer cise-induced immune changes. Methods: In a randomized cross-over place bo-controlled study, eight healthy male subjects performed three bouts of ergometer bicycle exercise lasting 60, 45, and 30 min at 75% of th eir (V) over dot O-2max separated by 2 h of rest. Results: The arteria l plasma glutamine concentration declined from 508 +/- 35 (pre-exercis e) to 402 +/- 38 mu M (2 h after the last exercise bout) in the placeb o trial and was maintained above pre-exercise levels in the glutamine supplementation trial. The numbers of circulating lymphocytes and the phytohemagglutinin-stimulated lymphocyte proliferative response declin ed 2 h after, respectively, during each bout of exercise, whereas the LAK cell activity declined 2 h after the third bout. Glutamine supplem entation in vivo, given in the described doses at the specific times, did not influence these changes. Conclusion: The present study does no t appear to support the hypothesis that those aspects of postexercise immune changes studied are caused by decreased plasma glutamine concen trations.