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- Title
Sustained Exposure to High Carbohydrate Availability Does Not Influence Iron-Regulatory Responses in Elite Endurance Athletes.
- Authors
McKay, Alannah K.A.; Peeling, Peter; Pyne, David B.; Tee, Nicolin; Welveart, Marijke; Heikura, Ida A.; Sharma, Avish P.; Whitfield, Jamie; Ross, Megan L.; van Swelm, Rachel P.L.; Laarakkers, Coby M.; Burke, Louise M.
- Abstract
This study implemented a 2-week high carbohydrate (CHO) diet intended to maximize CHO oxidation rates and examined the iron-regulatory response to a 26-km race walking effort. Twenty international-level, male race walkers were assigned to either a novel high CHO diet (MAX = 10 g/kg body mass CHO daily) inclusive of gut-training strategies, or a moderate CHO control diet (CON = 6 g/kg body mass CHO daily) for a 2-week training period. The athletes completed a 26-km race walking test protocol before and after the dietary intervention. Venous blood samples were collected pre-, post-, and 3 hr postexercise and measured for serum ferritin, interleukin-6, and hepcidin-25 concentrations. Similar decreases in serum ferritin (17–23%) occurred postintervention in MAX and CON. At the baseline, CON had a greater postexercise increase in interleukin-6 levels after 26 km of walking (20.1-fold, 95% CI [9.2, 35.7]) compared with MAX (10.2-fold, 95% CI [3.7, 18.7]). A similar finding was evident for hepcidin levels 3 hr postexercise (CON = 10.8-fold, 95% CI [4.8, 21.2]; MAX = 8.8-fold, 95% CI [3.9, 16.4]). Postintervention, there were no substantial differences in the interleukin-6 response (CON = 13.6-fold, 95% CI [9.2, 20.5]; MAX = 11.2-fold, 95% CI [6.5, 21.3]) or hepcidin levels (CON = 7.1-fold, 95% CI [2.1, 15.4]; MAX = 6.3-fold, 95% CI [1.8, 14.6]) between the dietary groups. Higher resting serum ferritin (p =.004) and hotter trial ambient temperatures (p =.014) were associated with greater hepcidin levels 3 hr postexercise. Very high CHO diets employed by endurance athletes to increase CHO oxidation have little impact on iron regulation in elite athletes. It appears that variations in serum ferritin concentration and ambient temperature, rather than dietary CHO, are associated with increased hepcidin concentrations 3 hr postexercise.
- Subjects
IRON metabolism; INTERLEUKINS; HEAT; CONFIDENCE intervals; TEMPERATURE; FERRITIN; TOXIC substance exposure; CARBOHYDRATE content of food; PHYSICAL fitness; WALKING (Sports); ATHLETES; MEDICAL protocols; PRE-tests &; post-tests; ENDURANCE sports; DESCRIPTIVE statistics; BODY mass index
- Publication
International Journal of Sport Nutrition & Exercise Metabolism, 2021, Vol 31, Issue 2, p101
- ISSN
1526-484X
- Publication type
Article
- DOI
10.1123/ijsnem.2020-0224