Cytokines and growth factors during and after a wrestling season in adolescent boys.
OBJECTIVE
Brief periods of aerobic exercise training lead to reductions, rather then the expected increases in circulating IGF-I. We hypothesized that intense exercise training in adolescents initially leads to simultaneous increases in proinflammatory cytokines and decreases in activity of the GH/IGF-I axis; and that as exercise training proceeds, levels of proinflammatory cytokines become reduced, and a rebound in IGF-I ensues leading to the higher IGF-I levels.


METHODS
To test this, we evaluated the GH/IGF-I axis and levels of inflammatory cytokines (IL-6, TNF-alpha, IL-1beta, IL-1ra), body composition, and fitness in 13 healthy adolescent boys (mean age 15.9 +/- 0.3 yr) over the course of a high-school wrestling season. Subjects were tested preseason, midseason (6 wk), peak season (12-14 wk), and 4 wk postseason.


RESULTS
No significant weight loss was noted throughout the season. During the wrestling season (mid and peak) both total (P < 0.046) and free (P < 0.002) IGF-I levels decreased, whereas proinflammatory cytokines (IL-1ra, P < 0.005; IGFBP-1, P < 0.013; and IGFBP-2, P < 0.025) increased. GHBP (P < 0.018) levels also decreased during the season. In the postseason, there were significant increases in GHBP, and free and total IGF-I, whereas proinflammatory cytokines decreased.


CONCLUSIONS
An initial catabolic-type hormonal response occurs with intense exercise training in adolescents. This is followed by a rebound in circulating growth factors when the period of heavy training ceases.
Nemet
Dan
D
Center for the Study of Health Effects of Exercise in Children, University of California, Irvine, Children's Hospital, College of Medicine, Orange, CA 92868, USA.
Pontello
Andria M
AM
Rose-Gottron
Christie
C
Cooper
Dan M
DM
D000293:Adolescent; D000704:Analysis of Variance; D001823:Body Composition; D015992:Body Mass Index; D016207:Cytokines / Q000097:blood*; D006133:Growth Substances / Q000097:blood*; D006801:Humans; D016014:Linear Models; D008297:Male; D010809:Physical Fitness; D014952:Wrestling / Q000502:physiology*
D016207:Cytokines; D006133:Growth Substances