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Effects of carbohydrate dose and frequency on metabolism, gastrointestinal discomfort, and cross‐country skiing performance
Author(s) -
Stocks B.,
Betts J. A.,
McGawley K.
Publication year - 2016
Publication title -
scandinavian journal of medicine and science in sports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.575
H-Index - 115
eISSN - 1600-0838
pISSN - 0905-7188
DOI - 10.1111/sms.12544
Subject(s) - carbohydrate , ingestion , carbohydrate metabolism , time trial , fructose , medicine , lipid oxidation , zoology , endocrinology , chemistry , food science , heart rate , biology , antioxidant , biochemistry , blood pressure
This study investigated carbohydrate ingestion of varied doses and frequencies during a simulated cross‐country skiing time trial. Ten men and three women (age: 30 ± 7 years;V ˙ O 2 m a x: 59.6 ± 5.7 mL/kg/min) completed four, 30‐km classic technique roller skiing time trials on a treadmill. A 1:1 maltodextrin‐fructose carbohydrate solution was provided at high (2.4 g/min; HC ) and moderate (1.2 g/min; MC ) ingestion rates, each at high (six feeds; HF ) and low (two feeds; LF ) frequencies. In the LF trials, blood glucose was elevated following carbohydrate ingestion (at 4 and 19 km) but was reduced at 14 and 29 km compared with HF strategies ( P ≤ 0.05). Gastrointestinal discomfort was higher in HC ‐ LF compared with all other trials ( P ≤ 0.05). Whole‐body lipid oxidation was lower and carbohydrate oxidation was higher in LF compared with HF trials ( P ≤ 0.05). While performance time was not significantly different between trials (140:11 ± 15:31, 140:43 ± 17:40, 139:12 ± 15:32 and 140:33 ± 17:46 min:s in HC‐HF , HC ‐ LF , MC ‐ HF , and MC ‐ LF , respectively; P > 0.05), it was improved with trial order ( P < 0.001). There was no effect of order on any other variable ( P > 0.05). Altering carbohydrate dose or frequency does not affect cross‐country ski performance. However, low‐frequency carbohydrate ingestion resulted in poorer maintenance of euglycemia, reduced lipid oxidation, and increased gastrointestinal discomfort.