Immune Responses to Strenuous Exercise and Carbohydrate Intake in Boys and Men
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Few studies describe immune responses to exercise in children, compared with adults, and none have investigated the influence of carbohydrate (CHO) intake. We hypothesized less perturbation and a faster recovery of the immune system with exercise in children, regardless of supplemental energy. Twelve boys (9.8 +/- 0.1 y) and 10 men (22.1 +/- 0.5 y) cycled for 60 min at 70% o(2max) while drinking 6% CHO (CHO-T) or flavored water (FW-T). Blood samples were collected before (PRE), immediately after (POST), and 60 min after (REC) exercise. Boys, compared with men, had smaller (p < 0.05) increases in total leukocytes (28% versus 38%), natural killer (NK) cells (78% versus 236%), and NK T cells (42% versus 128%) at POST, averaged across beverage trials. Exercise did not increase tumor necrosis factor-alpha (TNF-alpha), but significantly (p < 0.05) increased IL-6 in men (189%), but not in boys (11%). In both trials, lymphocytes and T cells at REC were suppressed (p < 0.05), relative to PRE, in men (-21%), but not in boys (4%). IL-6 remained elevated ( p< 0.001) in men at REC, with no change from POST in boys. In boys, but not in men, CHO significantly (p < 0.05) attenuated increases in neutrophil, lymphocyte, and NK cell counts at POST. Neutrophils at REC in CHO-T were lower (p < 0.05) than in FW-T in men ( approximately 25%) and in boys ( approximately 17%). CHO had no effect on TNF-alpha or IL-6 in either group. Our results indicate a distinct pattern of the immune response to exercise and CHO intake in boys, compared with men.
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