Immunological Changes in Response to Acute Exercise, Considering Puberty and Sex
This research was conducted to elucidate age-, puberty-, and sex-related effects on immunological changes in response to acute exercise. Compared with young men, 9-and 10-yr-old boys experienced smaller natural killer (NK) cell and interleukin-6 (IL-6) changes and a faster neutrophil and IL-6 recovery in response to exercise (Chapter 3). In these boys, exercise-induced neutrophil and NK cell changes were also more sensitive to carbohydrate (CHO) intake. The possible interaction of puberty and CHO intake on NK cell responses to exercise was then investigated in boys at the same chronological age (Chapter 4 ). The magnitude of change in NK cells was greatest in boys at advanced stages of puberty, and responses to CHO intake were most sensitive in prepubertal boys. To further investigate age-, puberty-, and sex-related differences in leukocyte and cytokine responses to exercise, boys and girls ages 12 and 14 were studied (Chapter 5). Neutrophil, lymphocyte, NK cell, and IL-6 responses were more pronounced in 14-yr-old versus 12-yr-old and in mid-versus early-pubertal girls. Age-and puberty-related differences in neutrophil recovery were also observed in the boys. Sex differences (girls> boys) in lymphocytes and NK cells were observed among 14-yr-old, but not 12-yr-old and among mid-, but not late-pubertal subjects. Finally, the effects of sex, menstrual phase (MP) and oral contraceptive (OC) use on leukocyte and IL-6 responses to exercise were studied in adults (Chapter 6). Compared with men, women experienced larger increases in lymphocytes, but MP did not influence immune changes. A novel observation was that OC use increased the magnitude of exercise-induced changes in leukocyte subsets. Collectively, the studies in this thesis represent the first comprehensive examination of age-, puberty-, and sex-related effects on immunological changes in response to exercise and provide the first reports of immune-related responses to CHO intake during exercise in children.