Page 88 - JSOM Fall 2021

Caffeine Gum Does Not Improve Marksmanship, Bound Duration,

Susceptibility to Enemy Fire, or Cognitive Performance During
Tactical Combat Movement Simulation

Jesse A. Stein*; Timothy C. Hepler; Justin A. DeBlauw; Cassandra M. Beattie;
Chaddrick D. Beshirs; Kendra M. Holte; Brady K. Kurtz; Katie M. Heinrich

ABSTRACT
Background: Military personnel supplement caffeine as a worn during direct-fire engagements. 7,18,26 Last, caffeine also
countermeasure during unavoidable sustained wakefulness. improves marksmanship accuracy and reaction time, which
However, its utility in combat-relevant tasks is unknown. This both depreciate in stressful environments. 11,13,15,27–30 While caf-
study examined the effects of caffeinated gum on performance feine represents a viable ergogenic target to support soldiers,
in a tactical combat movement simulation. Materials and it is unclear if caffeine can increase soldier survivability during
Methods: Healthy men (n = 30) and women (n = 9) (age = 25.3 direct-fire engagements.
± 6.8 years; mass 75.1 ± 13.1 kg) completed a marksmanship
with a cognitive workload (CWL) assessment and a fire-and- Blount and colleagues developed a model to predict suscep-
move simulation (16 6-m bounds) in experimental conditions tibility to enemy fire during tactical combat movements such
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(placebo versus caffeinated gum, 4mg/kg). Susceptibility to as direct-fire engagements. The susceptibility to enemy fire
enemy fire was modeled on bound duration during the fire- model was predicated on a soldier’s bound duration and ex-
and-move simulation. Results: Across both conditions, bound posure to enemy fire (e.g., longer bound duration, longer ex-
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duration and susceptibility to enemy fire increased by 9.3% posure, and increased susceptibility to enemy fire). Physical
and 7.8%, respectively (p = .001). Cognitive performance de- fatigue accumulates rapidly during repeated high- intensity
creased after the fire-and-move simulation across both con- sprints and exposure time progressively increases during di-
ditions (p < .05). However, bound duration, susceptibility to rect-fire engagements. 3,4,32 However, caffeine may mitigate
enemy fire, marksmanship, and cognitive performance did not performance decrements during direct-fire engagements by
differ between the caffeine and placebo conditions. Conclu- sustaining bound durations.
sion: These data do not support a benefit of using caffeinated
gum to improve simulated tactical combat movements. To the best of our knowledge, the effects of caffeine supple-
mentation on marksmanship and susceptibility to enemy fire
Keywords: caffeine gum; marksmanship; bound duration; en- during a tactical combat movement, simulating a direct-fire
emy fire; cognitive performance; tactical combat movement engagement, remain unknown. We hypothesized that perfor-
simulation mance would deteriorate during a tactical combat movement
simulation resulting in significant decrements in marksman-
ship, cognition, and susceptibility to enemy fire. Additionally,
we hypothesized that caffeine supplementation would signifi-
Introduction
cantly attenuate performance decrements in marksmanship,
In combat, warfighters are involved in direct-fire engagements cognition, and susceptibility to enemy fire during the tactical
that are responsible for nearly half of all casualties. Perfor- combat movement simulation.
1
mance during direct-fire engagements is critical and requires
soldiers to perform repeated high-intensity sprints. Addition-
ally, Soldiers deliver suppressive fire to protect friendly units Methods
advancing on hostile forces during recovery periods. Multi- Design
2–9
ple stressors act on warfighters that deteriorate physical and The study was approved by the Kansas State University Insti-
cognitive performance. These stressors, in turn, decrease com- tutional Review Board (#9821). Subjects attended four labo-
bat effectiveness. 3,10–12 Countermeasures to restore warfighter ratory visits. Subjects were informed of the study procedures,
performance in austere conditions have used pharmacological provided written consent, completed baseline measures, and
substances such as caffeine. 13–16 were familiarized with the tactical combat movement simula-
tion during the first laboratory visit. Subjects were randomized
Caffeine is an ergogenic aid that improves both physical and in a double-blind, counterbalanced, crossover design to deter-
cognitive performance. 17–22 Emerging evidence suggests that mine the effects of caffeine on performance during the tacti-
caffeine improves repeated sprint performance, which dete- cal combat movement simulation. The second laboratory visit
riorates during direct-fire engagements. 3,4,23–25 Additionally, served as a baseline (BL) control with no supplement provided
caffeine improves muscular strength and power, which may to the subject before completing the tactical combat movement
help soldiers tolerate heavy personal protective equipment simulation. The effects of caffeine (CAF) versus placebo (PLA)
*Correspondence to Jesse A. Stein, Kansas State University, College of Health and Human Sciences, Department of Kinesiology, 920 Denison
Ave., Natatorium 8, Manhattan, KS 66506, USA; or jesse.a.stein.ctr@mail.mil
All authors are from the Department of Kinesiology, College of Health and Human Sciences, Kansas State University, Manhattan, KS.

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