Attenuation of exercise-induced interleukin-6 (IL-6) responses by carbohydrate (CHO) has been demonstrated in studies comparing controlled doses (≥ 0.9 g · kg−1 · h−1) to placebo, but not in studies of voluntary intake. This study sought to determine if attenuation of the IL-6 response during a 32.2-km mountain trail race occurs for high compared to low ad libitum CHO intakes. IL-6, C-reactive protein (CRP), and creatine kinase activity (CK) were analyzed from blood samples collected 12 h pre-, 0, 4, and 24 h post-race. Subjects were grouped into low (n = 14, 0.4 ± 0.1 g · kg−1· h−1) and high (n = 18, 0.8 ± 0.2 g · kg−1 · h−1) CHO intake groups. IL-6 0 h post-race (P < 0.05) was higher in the low (40.2 ± 22.7 pg · mL−1) compared to the high CHO group (32.7 ± 22.1 pg · mL−1). CRP and CK both increased post-race, but no differences were observed between groups. Attenuation of exercise-induced IL-6 is apparent across a range of CHO intakes.
The authors are with the Dept of Health and Human Development, Montana State University, Bozeman, MT 59717.