Effect of carbohydrate or carbohydrate plus medium-chain triglyceride ingestion on cycling time trial performance.
This study examined the effectiveness of ingesting a carbohydrate or carbohydrate + medium-chain triglycerides (MCT) on metabolism and cycling performance. Eight endurance-trained men [peak O(2) uptake = 4.71 +/- 0.09 (SE) l/min] completed 35 kJ/kg as quickly as possible [time trial (TT)] while consuming 250 ml/15 min of either a 6% (wt/vol) carbohydrate solution (C), a 6% carbohydrate + 4.2% MCT solution (C+M), or a sweet placebo (P). Time to complete the set amount of work was reduced in both C and C+M compared with P by 7 and 5%, respectively (C: 166 +/- 7 min; C+M: 169 +/- 7 min; P: 178 +/- 11 min; P < 0.01). Plasma glucose concentration was maintained at or above resting values throughout both C and C+M trials but decreased (P < 0.05) below resting values in P at the completion of the TT. The estimated rate of carbohydrate oxidation was not different during the first 90 min of exercise but thereafter was reduced (P < 0.05) in P and was maintained in both C and C+M. These data demonstrate that carbohydrate ingestion during exercise improves 100-km TT performance compared with a sweet placebo, but the addition of MCT does not provide any further performance enhancement.
Angus
D J
DJ
Exercise Physiology and Metabolism Laboratory, Department of Physiology, The University of Melbourne, Parkville, Victoria 3052, Australia.
Hargreaves
M
M
Dancey
J
J
Febbraio
M A
MA
D000328:Adult; D001628:Beverages; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose / Q000187:drug effects; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005223:Fats / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008970:Molecular Weight; D010084:Oxidation-Reduction / Q000187:drug effects; D010100:Oxygen / Q000378:metabolism; D013997:Time Factors; D014280:Triglycerides / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005223:Fats; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides; D019344:Lactic Acid; D010100:Oxygen