UBC Theses and Dissertations
The effects of macro- and micro- nutrient timing on post-exercise hepcidin response in elite and professional athletes Dahlquist, Dylan Timothy
BACKGROUND INFORMATION Iron deficiency (ID) has debilitating effects on athletic performance, causing significant reductions (-34%) in VO₂max. Inflammation caused by exercise has been shown to impede iron absorption in the digestive tract by up-regulating the expression of the iron regulatory protein, hepcidin. To date, nutritional interventions to blunt hepcidin response have been few and equivocal. We investigated the effects of nutrient timing with essential macro- and micro- nutrients to potentially attenuate the post-exercise rise in hepcidin in highly trained athletes. PURPOSE To determine if a post-exercise drink consisting of whey protein isolate (25g) and carbohydrates (75g) with the addition of vitamins, D₃ (5,000 IU) and K₂ (1,000 mcg) (VPRO) or without D₃ and K₂ (PRO), following a bout of high-intensity interval exercise has an effect on the acute post-exercise hepcidin responses in athletes as compared to a non-caloric placebo drink (PLA). Our hypothesis was that both VPRO and PRO will significantly decrease hepcidin following a bout of high intensity exercise as compared to PLA, with VPRO supplementation having a greater effect on hepcidin versus PRO supplementation alone. METHODS Ten elite male cyclists (age: 26.9 ± 6.4 yrs; VO₂max: 67.4 ± 4.4 ml/kg/min) partook in four cycling sessions. A randomized, placebo-controlled, single-blinded triple crossover design was utilized. Experimental days consisted of an 8-min warm-up at 50% pVO₂max, followed by 8 x 3 min intervals at 85% pVO₂max with, 1.5 min at 60% pVO₂max between each interval. Blood samples were collected pre-exercise, post-exercise and three hours post-exercise. Three varying drinks (PRO, VPRO or PLA) were consumed immediately after the post-exercise blood sample. RESULTS/CONCLUSIONS The results from the investigation demonstrate that following a fatiguing interval-based cycling exercise in highly-trained athletes, subjects experienced a significant time-dependent increase in all biomarkers measured independent of post-exercise drink composition. In conclusion, the post-exercise drinks had no significant effect on any biomarker. The findings could potentially be related to the dosage of nutrients, the timing of blood samples, or the training status of individuals. The lack of an effect in either of the drinks on hepcidin and other biomarkers are contrary to our hypothesis.
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