Monday, October 22, 2012
Friday, October 5, 2012
Carbohydrate drinks and endurance performance
Study supports what I have been recommending for years, during endurance events like 10km or longer hydrate using a drink containing 4-7% carbohydrate for maximum performance and the least amount of digestive distress.In the study below, the carbohydrate was supplied in grams of CHO per liter of fluid per hour. 70 grams/liter is equivalent to 7% CHO in the drink.
Med Sci Sports Exerc. 2012 Oct 2. [Epub ahead of print]
Curvilinear Dose-Response Relationship of Carbohydrate (0-120 g•h-1) and Performance.
Source
1Gatorade Sports Science Institute, Barrington, IL 2Department of Kinesiology, Auburn University, Auburn, AL 3Scout Consulting, Hebron, IL 4Department of Health and Human Performance, University of Montana, Missoula, MT 5Department of Kinesiology, Louisiana State University, Baton Rouge, LA 6Dairy Research Institute, Rosemont, IL.Abstract
ABSTRACT: There is a lack of consensus regarding the optimal range of carbohydrate (CHO) ingestion rates recommended for endurance athletes. Purpose: This study investigated the relationship between CHO dose and cycling time-trial performance to identify an optimal range of CHO ingestion rates for endurance performance. Methods: Fifty-one cyclists and triathletes (28 ± 7 yr, mean ± SD) across four research sites completed four trials. Each trial consisted of a 2-h constant load ride at 95% of the workload that elicited a 4-mM blood lactate concentration immediately followed by a computer-simulated 20-km time-trial, which subjects were asked to complete as quickly as possible. Twelve CHO electrolyte (18 mmol•L Na, 3 mmol•L K, and 11 mmol•L Cl) beverages (three at each site) were tested in a double-blind manner, providing subjects 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 g CHO (1:1:1 glucose-fructose-maltodextrin)•h during the 2-h constant load ride at a fluid intake rate of 1 L•h. All subjects also consumed a non-caloric placebo on one counterbalanced test occasion. Data were natural log transformed, subjected to a mixed model analysis, and are reported as adjusted treatment means. Results: We estimate incremental performance improvements of 1.0, 2.0, 3.0, 4.0, and 4.7% at 9, 19, 31, 48 and 78 g•h respectively with diminishing performance enhancement seen at CHO levels greater than 78 g•h. Conclusion: CHO beverage ingestion and endurance (~160 min) performance appear to be related in a curvilinear dose-response manner, with the best performance occurring with a CHO (1:1:1 glucose-fructose-maltodextrin) ingestion rate of 78 g•h.- PMID:
- 22968309
- [PubMed - as supplied by publisher]
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