title: Brief, high intensity exercise alters serum ghrelin and growth hormone concentrations but not IGF-I, IGF-II or IGF-I bioactivity.
abstract: Exercise stimulates growth hormone (GH) release, but there are conflicting reports regarding the acute effects of exercise on circulating ghrelin and insulin-like growth factor (IGF) concentrations. This investigation examined (1) the effect of a single sprint on circulating GH, ghrelin and IGF concentrations as well as a marker of IGF-I bioactivity, and (2) whether the number of muscle actions performed during a sprint influences these responses. Seven healthy men completed 3 trials in a random order. In two exercise trials they performed a single 30-s sprint on a cycle ergometer against a resistance equivalent to either 7% (FAST) or 9% (SLOW) of their body mass. In the other they rested in the laboratory (CON). Blood samples were taken pre-, immediately post-, 10 and 30 min post-exercise, and at equivalent times in the CON trial. Total ghrelin concentrations declined after the sprint and were significantly lower after 30 min of recovery than they were pre-exercise (pre-exercise vs. 30 min; FAST, 0.62 (0.19) vs. 0.49 (0.16) microg/L, P<0.001; SLOW, 0.59 (0.15) vs. 0.47 (0.13) microg/L, P<0.001). GH concentrations increased in both exercise trials and were greater in the FAST than the SLOW trial. Serum concentrations of total IGF-I, free IGF-I, total IGF-II, and IGF-I bioactivity did not change after sprinting. In conclusion, sprint exercise suppresses total ghrelin concentrations and stimulates GH release but does not alter IGF concentrations or bioactivity.
authors.affiliation: Sport, Health and Exercise Science, University of Bath, Bath, UK. k.stokes@bath.ac.uk
authors.forename: Keith A
authors.initials: KA
authors.lastname: Stokes
authors.forename: Dave
authors.initials: D
authors.lastname: Sykes
authors.forename: Kate L
authors.initials: KL
authors.lastname: Gilbert
authors.forename: Jian-Wen
authors.initials: JW
authors.lastname: Chen
authors.forename: Jan
authors.initials: J
authors.lastname: Frystyk
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D054439:Ghrelin / Q000097:blood*; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008297:Male
chemical_list: D054439:Ghrelin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II