Serum Cytokines in Black and White Males After Eccentrically Biased Aerobic Exercise

Purpose: To determine the effect of eccentrically biased aerobic exercise and ethnic group on circulating cytokine levels. Methods: Seven black and eight white males (18 - 22 years), active but untrained, participated in the study. Subjects performed a 60-minute downhill run on a treadmill (gradient - 13.5%) at a speed eliciting 75% of their VO2 peak on a level grade. Venipunctures were performed before, immediately after (IA) and then at 3, 6, 9, 12, hours and at 1, 2 and 3 weeks after the run. Plasma creatine kinase (CK) activity and percentage change (pre vs each post time point) in 18 serum cytokines concentrations (measured using Bio-Plex Cytokine Assays, Bio-Rad, Hercules, CA) were compared using a two way (2 x 9) repeated measures ANOVA. Significance was set at P ≤ 0.05. Results: There was an interaction (P = 0.0055) and ethnic group effect (P <0.0001) for CK activity with consistently higher levels in the black group. CK increased over time after the run, peaking at 12 h for both groups. There were significant interaction effects for the percentage change in cytokine levels. These were significantly higher (ranging from 25% to 132%) in the black compared with the white group at multiple time points for IL-10 (P = 0.02, T-helper 2 cytokine), IFN-γ (P = 0.03, T-helper 1 cytokine), TNF-α (P = 0.05, proinflammatory), the chemokines CXCL 10 (P = 0.001), eotaxin (P = 0.02) and IL-8 (P = 0.05), G-CSF (P = 0.05, colony stimulating factor) and VEGF (P = 0.005, angiogenesis). Conclusions: CK was significantly higher in the black group suggesting greater muscle damage. Differences in the percentage change in the serum cytokines, in particular the chemokines and VEGF suggest a heightened immunological/inflammatory milieu in the circulation of the black group that may be the consequence of the extent of the exercise-induced muscle damage. The performance and health implications of this finding warrant further investigation.