Effect of red bull energy drink on auditory reaction time and maximal voluntary contraction

The use of "Energy Drinks" (ED) is increasing in India. Students specially use these drinks to rejuvenate after strenuous exercises or as a stimulant during exam times. The most common ingredient in EDs is caffeine and a popular ED available and commonly used is Red Bull, containing 80 mg of caffeine in 250 ml bottle. The primary aim of this study was to investigate the effects of Red Bull energy drink on Auditory reaction time and Maximal voluntary contraction. A homogeneous group containing twenty medical students (10 males, 10 females) participated in a crossover study in which they were randomized to supplement with Red Bull (2 mg/kg body weight of caffeine) or isoenergetic isovolumetric noncaffeinated control drink (a combination of Appy Fizz, Cranberry juice and soda) separated by 7 days. Maximal voluntary contraction (MVC) was recorded as the highest of the 3 values of maximal isometric force generated from the dominant hand using hand grip dynamometer (Biopac systems). Auditory reaction time (ART) was the average of 10 values of the time interval between the click sound and response by pressing the push button using hand held switch (Biopac systems). The energy and control drinks after one hour of consumption significantly reduced the Auditory reaction time in males (ED 232 ± 59 Vs 204 ± 34 s and Control 223 ± 57 Vs 210 ± 51 s; p < 0.05) as well as in females (ED 227 ± 56 Vs 214 ± 48 s and Control 224 ± 45 Vs 215 ± 36 s; p < 0.05) but had no effect on MVC in either sex (males ED 381 ± 37 Vs 371 ± 36 and Control 375 ± 61 Vs 363 ± 36 Newton, females ED 227 ± 23 Vs 227 ± 32 and Control 234 ± 46 Vs 228 ± 37 Newton). When compared across the gender groups, there was no significant difference between males and females in the effects of any of the drinks on the ART but there was an overall significantly lower MVC in females compared to males. Both energy drink and the control drink significantly improve the reaction time but may not have any effect on muscular performance. Energy drink per se is no better than control drink, which may indicate that there is no role of caffeine in the beneficial effect seen after the drinks.