Differing cytokine responses by ethnic groups to a bout of exercise-induced muscle damage: A preliminary report

Background: Strenuous exercise has been shown to alter immune and inflammatory responses potentially predisposing athletes to infection and injury. Ethnic disparities have been demonstrated in athletic performance and in the way individuals respond to exercise as well as in the predisposition towards certain diseases however, the information relating to immune and inflammatory responses to exercise between ethnic groups is still limited. The aim of this study was to investigate whether serum cytokine levels respond differently to eccentrically-biased exercise in African and Caucasian males. Methods: Seven black and 8 white males (18-22 years), active but untrained, participated in the study. Participants performed a 60-minute downhill run on a treadmill (gradient -13.5%) at a speed eliciting 75% of their VO₂peak on a level grade. Venipunctures were performed before, immediately after and then at 3, 6, 9, 12, 24 hours, and 1, 2 and 3 weeks afterwards. The following serum cytokine concentrations were quantified using the Bio-Plex suspension array system: IL-4, IL-6, IL-10, IL-Ira, IL-12p70, IFNγ, IL-7, IL-8, MCP-1, MIP-1β, eotaxin, IP-10, IL-1β, TNFα, GM-CSF, G-CSF, FGF basic and VEGF. Results: Significant differences between the two groups were evident from 6 hours postexercise onwards with the African runners maintaining significantly higher relative cytokine concentrations. IL-6 serum concentrations of the African runners, for example, ranged from 8% to 55.1% higher than that of the Caucasian runners from 6 hours to 2 weeks postexercise (P<0.05). Conclusions: The study demonstrated that the cytokine response to a bout of downhill running differs between African and Caucasian runners indicating that ethnicity may play a role in exercise-induced immune and inflammatory responses.