Effect of preexercise ingestion of modified cornstarch on substrate oxidation during endurance exercise.
The purpose of this study was to investigate differences in substrate oxidation between dextrose (DEX) and unmodified (UAMS) and acid/alcohol-modified (MAMS) cornstarches. Seven endurance-trained men (VO2peak = 59.1 +/- 5.4 mL.kg-1.min-1) participated in 2 h of exercise (66.4% +/- 3.3% VO2peak) 30 min after ingesting 1 g/kg body weight of the experimental carbohydrate or placebo (PLA). Plasma glucose and insulin were elevated after DEX (P < 0.05) compared with UAMS, MAMS, and PLA. Although MAMS and DEX raised carbohydrate oxidation rate through 90 min of exercise, only MAMS persisted throughout 120 min (P < 0.05 compared with all trials). Exogenous-carbohydrate oxidation rate was higher in DEX than in MAMS and UAMS until 90 min of exercise. Acid/alcohol modification resulted in augmented carbohydrate oxidation with a small, sustained increase in exogenous-carbohydrate oxidation rate. MAMS appears to be metabolizable and available for oxidation during exercise.
Johannsen
Neil M
NM
Health and Human Performance, Iowa State University, Ames, IA 50014, USA.
Sharp
Rick L
RL
D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D001944:Breath Tests; D050260:Carbohydrate Metabolism / Q000187:drug effects*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism*; D004311:Double-Blind Method; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010807:Physical Endurance / Q000187:drug effects / Q000502:physiology*; D013213:Starch / Q000008:administration & dosage / Q000378:metabolism*
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin; D013213:Starch; D005947:Glucose