VITAMIN-C SUPPLEMENTATION DOES NOT ALTER THE IMMUNE-RESPONSE TO 2.5 HOURS OF RUNNING

This randomized, double-blind, placebo-controlled study was designed t o determine the influence of vitamin C supplementation on the immune r esponse to 2.5 hr of high-intensity running. Twelve experienced marath on runners (VO2 max 51.6 +/- 1.5 ml.kg(-1).min(-1), age 40.5 +/- 2.0 y ears) were randomized into vitamin C (1,000 mg/day for 8 days) or plac ebo groups. On the test day, subjects ran at 75-80% VO2 max for 2.5 hr , with five blood samples taken before and for 6 hr after. Blood sampl es were analyzed for cortisol and catecholamines; leukocyte subsets; i nterleukin-6; natural killer cell activity; lymphocyte proliferation a s induced by concanavalin A, phytohemagglutinin, and pokeweed mitogen; and granulocyte phagocytosis and activated oxidative burst. Compared with placebo, vitamin C supplementation had no significant effect on t he pattern of change in any of these hormonal or immune measures follo wing 2.5 hr of intensive running.