title: Effect of exercise on cytokines and growth mediators in prepubertal children.
abstract: Many of the anabolic effects of exercise are mediated through insulin-like growth factor-I (IGF-I), but in adolescents, brief exercise training leads to reductions, rather than the expected increase, in circulating IGF-I. Certain cytokines--interleukin-(IL) 1beta (IL-1beta), IL-6 (IL-6), and tumor necrosis factor-alpha--are increased by exercise in adults and are known to inhibit IGF-I. To test the hypothesis that these cytokines might play a role in the adaptation to exercise, we measured the acute effects of exercise on selected cytokines and growth factors in 17 healthy 8- to 11-y-old children (4 females). Designed to mimic patterns and intensity of exercise found in the real lives of American children, the exercise protocol consisted of a 1.5-h soccer practice (of which about 40 min constituted of vigorous exercise). Pre- and postexercise urine and saliva samples were obtained in all subjects and both blood and urine in nine subjects. The exercise led to significant increases in circulating tumor necrosis factor-alpha (18 +/- 7%, p < 0.05) and IL-6 (125 +/- 35%, p < 0.01) as well as a significant increase in the antiinflammatory cytokine IL-1 receptor antagonist (33 +/- 10%, p < 0.01). Urine levels of IL-6 were also substantially increased by exercise (440 +/- 137%, p < 0.0001). Circulating levels of IGF-I were reduced to a small but significant degree (-6.4 +/- 3.2%, p < 0.05), although IGF-binding protein-1 (known to inhibit IGF-I) was substantially increased (156 +/- 40%, p < 0.001). Cytokines are systemically increased after relatively brief exercise in healthy children. This increase may alter critical anabolic agents such as IGF-I and its binding proteins.
authors.affiliation: Department of Pediatrics, University of California, Irvine, College of Medicine, 92697-4475, USA.
authors.forename: T P
authors.initials: TP
authors.lastname: Scheett
authors.forename: P J
authors.initials: PJ
authors.lastname: Mills
authors.forename: M G
authors.initials: MG
authors.lastname: Ziegler
authors.forename: J
authors.initials: J
authors.lastname: Stoppani
authors.forename: D M
authors.initials: DM
authors.lastname: Cooper
mesh_terms: D000328:Adult; D016207:Cytokines / Q000378:metabolism*; D004837:Epinephrine / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005260:Female; D006133:Growth Substances / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D053590:Interleukin 1 Receptor Antagonist Protein; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000097:blood; D012795:Sialoglycoproteins / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D006133:Growth Substances; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D015850:Interleukin-6; D012795:Sialoglycoproteins; D014409:Tumor Necrosis Factor-alpha; D007334:Insulin-Like Growth Factor I; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine