Caffeine Improves Reaction Time in Tactical Personnel

by | Dec 15, 2022 | 2022, Brain Health, Caffeine, Cognitive Health

Written by Chrystal Moulton, Staff Writer. A significant improvement and reaction time was observed among participants assigned caffeine and caffeine combination (P < 0.01).

tactical personnelPrevious studies have already shown the effect of caffeine on reaction time in law enforcement and military personnel i.e. tactical personnel1,2. However, other compounds similar to caffeine such as methylliberine and theacrine have similar pharmacodynamic effects like caffeine. Because the half-lives and peak time of each compound is different, researchers hypothesize the possibility of a synergistic effect of these compounds3-5. The combined pharmacokinetics of each molecule would suggest a sustained effect overtime5,6. In the current trial, researchers compared the effect of caffeine alone, a caffeine combination, and placebo on performance in tactical personnel6.

In a randomized placebo-controlled trial, researchers examined the effects of caffeine alone, caffeine in combination with methylliberine and theacrine, and placebo on marksmanship and vigilance in tactical personnel. Treatments were provided in the form of a capsule. Participants were randomly assigned to receive either 300 mg of caffeine, a combination of 150 mg caffeine, 100 mg methylliberine, and 50 mg theacrine, or 300 mg cellulose (placebo). Participants were required to maintain normal sleep and wake schedules during the one week before the experiment. They were also required to stop alcohol consumption 48 hours before testing and to abstain from caffeine 24 hours before testing. After consumption of their assigned test supplement, participants engaged in two rounds of testing comprised of vigilance, movement, and marksmanship tasks. Participants were allowed time to familiarize themselves with each task before official testing began. Reaction time and hemodynamic response were assessed after each round of testing. Felt arousal was measured at baseline and at 12 different time points throughout the protocol using the Felt Arousal Scale7. Cognitive decision making and accuracy scores were also analyzed for the vigilance, movement, and marksmanship tasks.

A total of 49 participants were recruited for this trial. Forty-eight participants completed the study. No significant differences were observed at baseline. For the vigilance task, researchers found a group by time interaction for reaction time results (F = 3.52, P = 0.038). However, the main effect on decision making scores was time (P = 0.021) with no effect on composites Z scores. Post hoc analysis revealed significant improvements in reaction time between round one and two in those assigned caffeine (P < 0.01, d = – 0.37) and the caffeine combination (P < is 0.01, d = – 0.32) but not the placebo (P = 0.27, d = -0.08). In the movement task, a main effect of time was also observed for measurements of reaction time (F = 44.17, P < 0.01). No group or group by time effects were found for reaction time (P > 0.22). For the marksmanship task, the main effect on accuracy was time (P < 0.05). No group or group by time effects were found for reaction time, accuracy, or composite Z scores (P > 0.20). Furthermore, in measurements of heart rate and felt arousal a main effect of time was found (P < 0.01).

In the end, participants randomly assigned to caffeine and the caffeine combination had a significant improvement in reaction time from round one to round two during the vigilance task. However, for the movement and marksmanship tasks, regardless of the treatment assigned, reaction time and accuracy improved from round one to round two due to time. Additional studies will be needed to assess the effect of caffeine and caffeine combination on reaction time and accuracy. Study limitations include the potential differences in training received by law enforcement, military, and ROTC and the use of a marksmanship simulator and airsoft pistol which do not match outdoor, live-fire conditions.

Source: Cintineo, Harry P., Marissa L. Bello, Alexa J. Chandler, Thomas D. Cardaci, Bridget A. McFadden, and Shawn M. Arent. “Effects of caffeine, methylliberine, and theacrine on vigilance, marksmanship, and hemodynamic responses in tactical personnel: a double-blind, randomized, placebo-controlled trial.” Journal of the International Society of Sports Nutrition 19, no. 1 (2022): 543-564.

© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

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Posted December 15, 2022.

Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.

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