Page 89 - JSOM Fall 2021

were evaluated with order randomized between participants and cognitive workloads (Figure 1). Subjects wore a 25-kg
on the third and fourth laboratory visits. Laboratory visits 1, weight vest during the tactical combat movement simula-
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2, and 3 were separated by at least 48 hours. Laboratory visits tion to replicate a combat load. Subjects wore exercise attire
3 and 4 were separated by at least 96 hours for a washout during the familiarization period (i.e., visit 1). Subjects wore
period. All trials occurred indoors in temperature-controlled a military issued combat uniform and boots during all other
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conditions set to 22°C as previously described. Subjects were sessions (i.e., visits 2 –4). The tactical combat movement simu-
asked to maintain their physical activity and dietary habits lation initiated with a marksmanship and cognitive workload
throughout the study. They were also asked to abstain from protocol. An M4 was modified with a shot, indicating reset-
vigorous physical activity 24 hours before testing, and from ting trigger automatic rifle bolt (SIRT-AR Bolt, Next Level
caffeine and alcohol 12 hours before testing. Training, https://nextleveltraining.com/product/sirt-bolt/), so
squeezing a trigger emitted a laser from the M4. Laser Ac-
Subjects tivated Shot Reporter software (Shooter Technology Group,
Participants were recruited using flyers, in-person presenta- https://lasrapp.com/) was used to acquire marksmanship data.
tions, social media, and email listservs surrounding the greater The marksmanship with cognitive workload protocol was
Kansas State University and Fort Riley area. In an attempt to modified from the Army Research Laboratory to reflect sim-
recruit military personnel, focus was placed on recruiting in ulated shooting. Four targets were mounted to the wall to
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areas with higher proportions of military groups (e.g., ROTC simulate distances of 18, 100, 150, and 200 meters. All targets
buildings, veteran centers, and military installations). Civil- were E-type target silhouettes and had colored backgrounds
ians, including college-aged students, were also permitted to be of yellow, red, green, or blue. The L.A.S.R. software randomly
in the study based on inclusion and exclusion criteria. Subjects called out a target color every 4 seconds until 12 targets were
completed a screening questionnaire to ensure that they were announced. Target callouts were announced electronically us-
in good health, non-tobacco-users, did not possess a condition ing an external speaker. Subjects were asked to aim the mod-
that would be worsened by physical activity, and reported reg- ified M4 and engage the targets by squeezing the trigger as
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ular caffeine use (≥50mg per day of caffeine). Daily caffeine quickly and as accurately as possible. The modified M4 had an
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consumption was evaluated using a 7-day caffeine recall. A iron sight aiming platform that subjects used for accuracy. All
Snellen Visual Acuity Test was used to verify that subjects had subjects confirmed the iron sight’s accuracy before each sim-
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at least 20/30 vision. Corrective lenses were allowed during ulation. Subjects were allowed one trigger squeeze per target
the visual acuity test and required for all testing. Laboratory callout. The number of correctly engaged targets (i.e., marks-
personnel verified that all inclusion and exclusion criteria were manship accuracy) was scored by the L.A.S.R. software. The
satisfied before experimentation. Subjects also demonstrated L.A.S.R. software also reported the time series data for target
proficiency with marksmanship by either providing evidence engagement. The duration between the first target call-out and
of a military rifle qualification in the last 12 months (n = the first target engagement was the first shot reaction time.
8), or by successfully engaging 12 targets with at least 75% The average duration between all target call-outs and target
accuracy using a modified M4 device (n = 31). Thirty-nine engagements was the marksmanship reaction time. The four
subjects qualified for the study (age 25.3 ± 6.8 years; height target configurations were generated, randomly assigned, and
177.1 ± 21.6 cm; mass 75.1 ± 13.1 kg; body fat percent 20.8 counterbalanced across sessions.
± 8.2%; fat-mass 15.8 ± 7.2 kg; fat-free mass 59.3 ± 10.7 kg;
men n = 30). Height was measured using a stadiometer. Body Cognitive workload was induced with a mathematical problem-
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mass, body fat percentage, fat-mass, and fat free mass were solving task similar to that of the Army Research Laboratory.
determined using bioelectrical impedance analysis in standard An auditory message was presented to the subjects through
mode (TBF-300A; Tanita, Japan). the external speaker. The auditory message was delivered in
between target callouts and contained mathematical problems
Supplementation Protocol that were moderate in difficulty and consisted of addition and

Subjects chewed approximately 4mg/kg body mass of caf- subtraction of single and double-digit numbers. Subjects ver-
feinated Military Energy Gum (Market Right Inc., https:// bally answered the mathematical problems before engaging the
militaryenergygum.com/) or placebo gum during sessions 3 next target callout. Twelve auditory messages were presented
and 4. The mode of delivery and dose was selected based on to the subject. The number of correctly answered mathemati-
use in the military and previous research. 16,36 Each piece of cal problems was used as an index of cognitive performance.
gum contained 100mg of caffeine. Pieces of gum were cut in Four sets of mathematical problems were generated, randomly
half to achieve approximately a 4mg/kg body mass dose to the assigned, and counterbalanced across sessions.
closest 50mg increment. The placebo gum was provided by
the manufacturer to replicate the color, taste, size, and texture After answering the last mathematical problem, subjects tran-
of the caffeinated gum. Subjects chewed two boluses of gum sitioned to a fire-and-move simulation to induce a combat-
similar to what was described by Lane and colleagues. Each relevant physical workload. The fire-and-move simulation
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bolus of gum was chewed for at least 10 minutes based on the protocol was modified from Silk and Billing’s protocol, which
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buccal absorption of caffeine. Subjects initiated a standard- is used in the Australian Army Combat Arms Physical Em-
ized warm-up 10 minutes after the second bolus of gum, fol- ployment Standards Assessment. 2,41 Subjects performed 16 × 6
lowed by the tactical combat movement simulation. Subjects meter bounds on a 20 second cycle. Subjects carried a sep-
returned after a minimum of 96 hours and performed the tacti- arate modified M4 to ensure the modified M4 used for
cal combat movement simulation with the opposite gum. 24,25,39 marksmanship-maintained calibration. An auditory message
was used to instruct subjects to initiate each bound. All
Tactical Combat Movement Simulation bounds started from the prone position and terminated in
The tactical combat movement simulation required subjects to the kneeling position. Subjects readopted the prone position
engage a series of targets with a modified M4 under physical before initiating the subsequent bound. The duration of each

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