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.
Mary P. Miles, Erin E. Walker, Stephen B. Conant, Shelly P. Hogan and Jessy R. Kidd
Mary P. Miles, Sherri D. Pearson, Jan M. Andring, Jessy R. Kidd and Stella L. Volpe
The purpose of this investigation was to determine whether carbohydrate supplementation during the frst 2 d post exercise recovery influenced the inflammation (IL-6, C-reactive protein [CRP], and cortisol) and muscle-damage responses. Eight participants performed a high-force eccentric elbow-fexion exercise to induce muscle soreness and inflammation and then consumed carbohydrate (0.25 g·kg−1·h−1) or an equal volume of placebo during hours 0–12 and 24–36 post exercise in a double-blind, crossover protocol. Muscle soreness; mid brachial arm circumference; blood glucose, IL-6, CRP, cortisol, and creatine-kinase (CK) activity; and maximal force production were measured pre exercise and 4, 8, 12, 24, 48, and 120 h post exercise. Plasma IL-6 increased, F(5) = 5.27, P < 0.05, 8 h post exercise, with no difference between carbohydrate and placebo conditions. Changes in muscle soreness, arm circumference, strength, and serum CK activity were consistent with small amounts of muscle damage and did not differ between conditions. The authors conclude that carbohydrate supplementation during recovery from soreness-inducing exercise does not influence the delayed IL-6 response temporally linked to inflammation or indications of muscle damage. Thus, increased carbohydrate consumption at levels consistent with recommendations for replenishing glycogen stores does not impair or promote the immune and muscle responses.