Fig. 1.

The response of IL-6, sIL-6R and sgp130 to a submaximal exercise bout to fatigue. * denotes a significant difference from rest, P < 0.05 (n = 12). At least one week after the initial test, subjects visited the laboratory after a 12 h fast and having avoided any alcohol, caffeine or strenuous exercise for 24 h prior to testing. To ensure euhydration, subjects consumed 1 l of water the night before and 0.5 l 2 h before the experiment. Previous work from our laboratory has shown that this preparation ensures euhydration, as measured by urine specific gravity (Marshall et al. 2006). Subjects then performed cycling exercise at 96 ± 6% LT until volitional exhaustion with water permitted ad libitum throughout. Blood samples were obtained by venepuncture (20 G Insyte-W, BD, USA) from an antecubital vein at rest and immediately post-exercise. Blood samples were collected in K⁺EDTA tubes. For glucose analysis blood was aliquoted into perchloric acid, centrifuged and the supernatant frozen at −80°C until analysis. For cytokine determination blood samples were centrifuged, the plasma removed and frozen at −80°C until analyses. Samples were assayed in duplicate for IL-6 (CV = 6.4%), sIL-6R (CV = 3.4%) and sgp130 (CV = 3.4%) via enzyme-linked immunosorbent assay using commercially available antibody pairs (IL-6:OptEIA IL-6 set; sIL-6R: M5 capture Ab and M182 detection Ab, and sgp130:A1 capture Ab and D2 detection antibody, all from BD Biosciences, Oxford, UK). Blood glucose (CV = 1.7%) was also measured spectrophotometrically using commercially available kits (Randox, UK). Pre and post-exercise blood samples were compared via paired t-tests. Significance was accepted at P < 0.05. Data are presented as Mean ± SD