Consumption of caffeine-containing beverages improves sustained attention and alertness but has no effect on strength or static muscular endurance

Abstract

Energy drinks are widely consumed for their caffeine content and related ergogenic effects. Many energy drinks also contain additional ingredients purported to enhance both physical and cognitive performance; however, it remains unclear whether these benefits are attributable solely to caffeine or the synergistic effect of other ingredients. The purpose of this study was to assess the effects of an energy drink vs. a caffeine-matched control on measures of sustained attention. Using a randomised, double-masked design ( n = 116), subjects were assigned to an energy drink (C4 – Nutrabolt®) or a caffeine-matched control (200 mg caffeine). The following assessments were conducted before and approximately 45 min after consuming an energy drink or caffeine-matched control: psychomotor vigilance test (PVT), MemTrax (memory), handgrip strength, and wall-sit endurance. Both the energy drink and the caffeine-matched control improved pre vs. post for the PVT (i.e. reaction time improved); however, there were no differences in the delta score. The energy drink group showed a significant decrease in the MemTrax assessment (% correct), whereas reaction time increased, with no change in the control group. However, there were no differences in the delta score between groups for either the % correct score or reaction time. There were no significant differences in the handgrip or wall-sit assessments between the two groups. There are no significant differences between the effects of consuming an energy drink or caffeine. Both beverages improved sustained attention and alertness likely due to the effects of caffeine. There were no differences in memory, handgrip strength, or wall-sit endurance.