Acute dietary carbohydrate manipulation and the subsequent inflammatory and hepcidin responses to exercise

Claire E. Badenhorst, Brian Dawson, Gregory R. Cox, Coby M. Laarakkers, Dorine W. Swinkels, Peter Peeling

To examine the effects of 24-h controlled carbohydrate intake on next day pre- and post-exercise inflammatory and hepcidin responses. In a crossover design, 12 well-trained endurance athletes (Ht 181.08 ± 7.68 cm; Wt 74.8 ± 11.5 kg, VO2peak 68.9 ± 7.2 ml kg(-1) min(-1)) completed two experimental (2-day) trials. On day 1, participants completed a glycogen depletion task, including a 16-km run (80 % vVO2peak) and 5 × 1 min efforts (130 % vVO2peak) separated by 2-min recovery. Subsequently, strict dietary control was enforced for 24 h, where low carbohydrate (LCHO 3 g kg(-1)) or high carbohydrate (HCHO 10 g kg(-1)) diets were provided. Twenty-four hours later, participants completed an 8 × 3 min interval running session at 85 % vVO2peak followed by 3-h monitored recovery. Venous blood samples were collected pre-, immediately post- and 3-h post-exercise, which were analyzed for interleukin-6, serum iron, ferritin and hepcidin. Interleukin-6 was elevated (p < 0.001) immediately post-exercise compared to baseline in both conditions, but was lower in HCHO (p = 0.015). Hepcidin levels were also lower at baseline (p = 0.049) in HCHO, and a large effect (d = 0.72) indicated a trend for lower levels at 3-h post-exercise compared to LCHO. Serum iron was increased post-exercise for both trials (p = 0.001), whereas serum ferritin remained unchanged. Twenty-four hours of controlled low carbohydrate intake resulted in higher baseline hepcidin levels and post-exercise IL-6 responses than a high carbohydrate intake. Such hormone increases may be induced by gluconeogenic signaling of the liver, and may negatively impact an athlete's iron metabolism.