Red Bull energy drink has led the 5 Billion dollar industry with more than 50% of all revenues. Since the popular emergence of energy drinks in 2002, there is now a popular trend toward sugar-free energy drinks that are mostly charged with caffeine. Caffeine is one of the most widely used ergogenic aids that various research studies have demonstrated increase aerobic endurance and reduce fatigue when consumed 60 minutes prior to workouts. However these “caffeine –endurance” studies included energy drinks that contained both carbohydrates and caffeine. Benefits of caffeine have been attributed to the increase in central nervous system activity. However, there are health concerns with excessive use of caffeine including impaired glucose tolerance, gastrointestinal irritation, anxiety, irritability and nausea, and tachycardia (abnormal rapid heart rate). A few studies have investigated the effects of lower dose caffeine (< 3 mg-kg-1) with carbohydrates due to the concerns of high caffeine intake. One such study by Cox et al (1) replaced a sports drink with the caffeinated soft drink Coke. Cycling performance with Coke was enhanced over placebo by 3.3%. Also, Forbes et al (2) found that regular Red Bull energy drink (2mg-kg-1) increased total bench press repetitions over 3 sets in young adults over placebo.
How well would young adults perform on a sugar-free Red Bull versus a placebo for Run Time-To –Exhaustion and would they feel less fatigued? This type of study was chosen by Candow et al (3) as this type of exercise demand may have application for sporting events which involve acute bursts of speed to finish line such as cross country skiing and triathlons.
Seventeen university students (9 men 8 women) who were performing regular physical activity like running, cycling, and weight training 3-5 times per week, were recruited. All subjects were also low-to moderate caffeine consumers. The study was a double-blind crossover, repeated measure design. Participants were randomized to supplement with Sugar-free Red Bull or placebo 60 minutes before exercise separated by a 7 day period to ensure adequate recovery and to allow adaptation of caffeine withdrawal before the next exercise bout. The placebo was a supplement drink of lemon-lime flavored soft drink, tonic water, lime juice. All the subjects completed the study and 9 correctly guessed when they were taking Red Bull or the placebo. Five subjects incorrectly guessed which drink they were consuming, and 3 subjects did not know.
Results: There was no significant difference in Time-To-Exhaustion between groups. Two subjects reported lower Rate of Perceived Exertion (RPE) compared with placebo, whereas 15 subjects reported no change between sugar-free Red Bull and placebo. This study surprised researchers as they anticipated an improved performance and reduced RPE much like studies with caffeine and sugar.
Discussion: Would the inclusion of a carbohydrate and caffeine drink make for significant differences? Would higher amounts of caffeine have made a difference? What is the moral responsibility of researchers in studies testing with high caffeine doses? How many people are performing at these intensities? Are you one of them?
1 Cox,Gr, Desbrow,B, Montgomery, PG, Anderson, ME, Bruce, CR, Theodore, AM, Martin, DT, Moquin, A. Roberts, A. Hawkley, JA. and Burke, LM. Effects of different protocols of caffeine intake on metabolism and endurance performance. J Appl Physiol 93: 990-999, 2002
2 Forbes, SC, Candow, DG, Little, JP, Magnus, C, and Chilibeck, PD. Effect of Red Bull Energy drink on repeated Wingate cycle performance and bench press muscular endurance. Int J Sprots Nutr Exerc Metab 17 : 433-444, 2007
3 Candow, DG, Kleisinger, AK, Grenier, S, and Dorsch, KD. Effect of Sugar-Free Red Bull Energy Drink on High Intensity Run Time-To-Exhaustion In Young Adults. J Strength and Cond Res 23: 1271-1275, 2009
