Abstract
Background:
Caffeine and carbohydrates are used by consumers to increase exercise and certain aspects of cognitive performance. This study investigated the effectiveness of an energy drink (ED) containing caffeine to enhance cycling time-trial performance and cognitive performance at rest, during strenuous exercise, and after exercise.
Methods:
The experimental protocol was a double-blind, placebo-controlled, randomized, crossover design. The treatments were ED containing caffeine (160 mg), carbohydrate (54 g), taurine, and Panax ginseng, and a caffeine-free noncaloric placebo beverage (PLA). After a 12-hour calorie and caffeine abstention, exercise performance was measured by time to finish a simulated 35-km cycling time-trial course. Cognitive performance was measured by a Stroop Test, a tapping task, a reaction time task, and an executive function task consisting of both tapping and reaction time. Participants (n=15, seven women, eight men) were grouped as low-baseline (LO) or high-baseline (HI) since 5 of 15 participants (3 women, 2 men) had elevated baseline blood caffeine concentrations at both experimental trials.
Results:
Race performance improved by an average of 3% in both LO and HI groups when participants consumed ED compared with PLA. Although VO2 and heart rate were greater throughout the race for ED compared with PLA, there was no difference in perceived exertion between treatments. ED also increased taps per second in the tapping task before and after exercise.
Conclusions:
The results suggest that ED is an effective pre-exercise supplement that can improve cycling time-trial performance and possibly simple aspects of cognitive function even under elevated basal blood caffeine levels.
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