Acute dietary carbohydrate manipulation and the subsequent inflammatory and hepcidin responses to exercise.
OBJECTIVE
To examine the effects of 24-h controlled carbohydrate intake on next day pre- and post-exercise inflammatory and hepcidin responses.


METHODS
In a crossover design, 12 well-trained endurance athletes (Ht 181.08 ± 7.68 cm; Wt 74.8 ± 11.5 kg, VO 2peak 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 % vVO 2peak) and 5 × 1 min efforts (130 % vVO 2peak) 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 % vVO 2peak 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.


RESULTS
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.


CONCLUSIONS
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.
School of Sport Science, Exercise and Health, The University of Western Australia, M408, 35 Stirling Hwy, Crawley, WA, 6009, Australia. badenhorstclaire1@gmail.com.
Claire E
CE
Badenhorst
School of Sport Science, Exercise and Health, The University of Western Australia, M408, 35 Stirling Hwy, Crawley, WA, 6009, Australia.
Brian
B
Dawson
Sports Nutrition, Australian Institute of Sport, Gold Coast, QLD, Australia.
Gregory R
GR
Cox
Department of Laboratory Medicine (LGEM 830), Radboud University Medical Center, Nijmegen, The Netherlands.|Hepcidinanalysis.com, Geert Grooteplein 10 (830), 6525 GA, Nijmegen, The Netherlands.
Coby M
CM
Laarakkers
Department of Laboratory Medicine (LGEM 830), Radboud University Medical Center, Nijmegen, The Netherlands.|Hepcidinanalysis.com, Geert Grooteplein 10 (830), 6525 GA, Nijmegen, The Netherlands.
Dorine W
DW
Swinkels
School of Sport Science, Exercise and Health, The University of Western Australia, M408, 35 Stirling Hwy, Crawley, WA, 6009, Australia.
Peter
P
Peeling
D000293:Adolescent; D000328:Adult; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000009:adverse effects*; D015444:Exercise; D005293:Ferritins / Q000097:blood; D064451:Hepcidins / Q000097:blood*; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D007501:Iron / Q000097:blood; D008297:Male
D004040:Dietary Carbohydrates; D064451:Hepcidins; D015850:Interleukin-6; D005293:Ferritins; D007501:Iron
Athletes; Carbohydrates; Inflammation; Iron metabolism