A small increase in performance is often the difference between winning and losing for athletes, and energy supplements are marketed to give them a competitive edge. One such supplement is XS® Energy Drink which contains B vitamins, caffeine, taurine, and an herbal adaptogen blend. XS® Energy Drink is primarily designed and marketed as an alertness stimulus; however, it is also marketed to athletes as a performance enhancing supplement. The hypothesis of this investigation was that the consumption of XS® Energy Drink before exercise would increase aerobic capacity (an increase in Vo2max) and time to fatigue, and would decrease time for recovery from the exercise bout. Twelve 18-24 year old athletes performed two Vo2max tests following a modified Ellestad Treadmill protocol. Prior to testing, a double-blind cross-over method was used to administer the energy supplement or the placebo. Vo2max (p=0.99), time to muscle fatigue (p=0.48), maximum heart rate (p=0.66), VEmax (p=0.10), time at which R is greater than 1 (p=0.50), or recovery time to one half Vo2max (p=0.67) were not significantly different with ingestion of XS® Energy Drink over placebo. The second trial was significantly longer than the first (p=0.01) likely due to the desire to improve exercise time or familiarization with the testing procedures. Results showed no physiological effects of XS® Energy Drink; however, there is a possibility of psychological advantage.
Sheehan, K. M.,
& Hartzler, L. K.
(2011). Effects of XS® Energy Drink on Aerobic Exercise Capacity of Athletes. International Journal of Exercise Science, 4 (2), 8, 152-163.