Carbohydrate feedings 1 h before exercise improves cycling performance

• Published in: The American journal of clinical nutrition Vol. 54; no. 5; pp. 866 - 870
• Main Authors: Sherman, WM, Peden, MC, Wright, DA
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.11.1991; American Society for Clinical Nutrition
• Subjects: ACIDE GRAS; ACIDE LACTIQUE; ACIDO LACTICO; ACIDOS GRASOS; ACTIVIDAD FISICA; ACTIVITE PHYSIQUE; ADDITIF ALIMENTAIRE; ADITIVOS ALIMENTARIOS; Adult; ADULTE; ADULTOS; ADULTS; BICYCLING; Biological and medical sciences; blood glucose; Blood Glucose - analysis; BLOOD SERUM; BLOOD SUGAR; CARBOHIDRATOS; carbohydrate oxidation; CARBOHYDRATES; DIET; DIETA; Dietary Carbohydrates - metabolism; Dietary Carbohydrates - pharmacology; exertion; Exhaustion; FATTY ACIDS; Fatty Acids, Nonesterified - blood; FOOD ADDITIVES; FREQUENCE DU POULS; Fundamental and applied biological sciences. Psychology; GLICEMIA; GLUCIDE; GLYCAEMIA; GLYCEMIE; Heart Rate; HOMBRES; HOMME; Humans; INSULIN; Insulin - blood; INSULINA; INSULINE; LACTIC ACID; LOISIR; Male; MEN; Metabolisms and neurohumoral controls; Osmolar Concentration; Oxidation-Reduction; Oxygen Consumption; PHYSICAL ACTIVITY; Physical Exertion; preexercise feeding; Pulmonary Gas Exchange; PULSACIONES; PULSE RATE; RECREACION; RECREATION; REGIME ALIMENTAIRE; SERUM SANGUIN; Space life sciences; SUERO SANGUINEO; SUPPLEMENTS; Time Factors; Vertebrates: anatomy and physiology, studies on body, several organs or systems; YOUNG ADULTS; carbohydrate oxidation; blood glucose; preexercise feeding; exertion; Exhaustion; Physical exercise; Human; Carbohydrate; Physical performance; Diet; Glycemia
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/54.5.866

The effects of consuming two different amounts of liquid carbohydrate 1 h before exercise on the metabolic responses during exercise and on exercise performance were determined. Subjects consumed either 1.1 g (LC) or 2.2 g (HC) carbohydrate/kg body mass or a placebo (P). Subjects cycled at 70% of maximal oxygen consumption (VO2max) for 90 min and then underwent a performance trial. Blood glucose and insulin responses during exercise were different among the three trials. Total carbohydrate oxidation was greater for the carbohydrate trials compared with P. Time-trial performance was significantly improved by LC and HC. Despite elevated insulin concentrations at the start of and during exercise, and despite an initial drop in blood glucose, consumption of between 1.1 and 2.2 g liquid carbohydrate/kg body mass 60 min before moderately intense prolonged exercise can improve performance, presumably via enhanced carbohydrate oxidation.