title: Effects of carbohydrate dose and frequency on metabolism, gastrointestinal discomfort, and cross-country skiing performance.
abstract: 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.
authors: Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden.|Human Physiology Research Group, Department for Health, University of Bath, Bath, UK.
authors: B
authors: B
authors: Stocks
authors: Human Physiology Research Group, Department for Health, University of Bath, Bath, UK.
authors: J A
authors: JA
authors: Betts
authors: Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden.
authors: K
authors: K
authors: McGawley
mesh_terms: D015746:Abdominal Pain / Q000209:etiology; D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000009:adverse effects*; D005080:Exercise Test; D005260:Female; D005632:Fructose / Q000008:administration & dosage / Q000009:adverse effects; D006339:Heart Rate; D006801:Humans; D050356:Lipid Metabolism; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D005082:Physical Exertion; D011134:Polysaccharides / Q000008:administration & dosage / Q000009:adverse effects; D012865:Skiing / Q000502:physiology*; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D011134:Polysaccharides; D005632:Fructose; C008315:maltodextrin
keywords: Endurance performance; Nordic skiing; glucose; multiple-transportable carbohydrate; roller skiing