Effect of Caffeine, Guarana, and Ginseng on Caloric Expenditure and Substrate Utilization During and After Exercise

Abstract

Background: Energy drinks are often marketed to increase metabolic rate both at rest and during exercise. However, there is no research on how the common combination of caffeine, guarana, and ginseng (CGG), with and without carbohydrate (CHO) consumption, effects exercise and post-exercise metabolism. PURPOSE: The purpose of the present study was to assess how 1.5mg/kg caffeine, 3.75mg/kg ginseng, 0.2mg/kg guarana, and 0.5g/kg carbohydrate affects caloric expenditure and fuel utilization both during and after moderate intensity treadmill running. METHODS: Three males (age: 24 ±3) and four eumenorrheic females (age: 21 ± 1) completed four testing protocols in random order during which they received a beverage containing CGG, CGG/CHO, CHO, or a placebo 5 minutes prior to engaging in a 30 minute bout of treadmill running at 75% VO2 peak. Caloric expenditure and respiratory exchange ratio (RER) were measured via continuous indirect calorimetry during exercise and for 2 hours into the recovery period. RESULTS: Caloric expenditure did not differ between the conditions during or after exercise. Although there were no differences between conditions in RER values during exercise, there was a significant condition by time interaction on RER during recovery. CHO had a higher mean RER value compared to placebo (p <.05) during the first hour of recovery, whereas during the second hour of recovery, mean CHO RER was higher than the mean CGG/CHO RER (p <.05) Conclusions: When consumed with carbohydrate, immediately prior to exercise, the combination of caffeine, guarana, and ginseng does not influence caloric expenditure, but does blunt the oxidation of carbohydrate during exercise recovery.