Medicine & Science in Sports & Exercise:
D-30 Free Communication/Poster - Macronutrient Metabolism II - Carbohydrates: JUNE 2, 2011 1:00 PM - 6:00 PM: ROOM: Hall B
Petrella, John K.; Aiken, Alan; Jung, Alan P.
Samford University, Birmingham, AL. (Sponsor: Scott Bickel, FACSM)
(No relationships reported)
PURPOSE: The purpose of this study was to examine changes in blood glucose after various methods of carbohydrate supplementation during a standardized bout of cycling.
METHODS: Eight moderately active males (21 ± 1 years, 85 ± 11 kg) performed three trials of a 60 minute cycling bout at 70% VO2 max. For each trial, the subject received one of three types of carbohydrate supplements: a 5% liquid carbohydrate supplement (Gatorade Endurance Formula, Chicago, IL) and a 9% gel-based supplement (PowerGel, PowerBar Energy Gel, Berkley, CA) taken without and with 16oz of water (PowerGel with water). Each supplementation trial provided 27g of carbohydrate. Trials were counterbalanced and separated by at least 48 hours. Blood glucose and heart rate were recorded at baseline, at each five-minute interval during exercise, and post exercise. A repeated measures ANOVA was used to detect differences between trials. All data are reported as means and standard deviations.
RESULTS: Subjects did not differ in heart rate at baseline (83-86 bpm, p=0.78) or in response to exercise during the three trials (p=0.21 -0.95). There were no difference in glucose at baseline prior to the ingestion of the supplement (Gatorade, 84.9 ± 12 mg/dl; PowerGel, 85.3 ± 7 mg/dl; 84.9 ± 5 mg/dl, p=0.98). With Gatorade, blood glucose peaked at 105.1 ± 15 mg/dl after 15 min of exercise. At 60 min of exercise, blood glucose dropped below baseline values (66.9 ± 3 mg/dl). With PowerGel, blood glucose never significantly changed from baseline (p=0.89-0.99). When consuming PowerGel with water, blood glucose peaked at 99.1 ± 15 mg/dl after 15 min of exercise and returned to values similar to baseline at 60 minutes (p=0.99).
CONCLUSION: The type of carbohydrate supplement and fluid volume can influenced both the time to peak blood glucose and the ability to maintain blood glucose during 1hr of exercise.