Page 27 - JSOM Spring 2025

Stress Shoot range, and finishing where they began testing (8km total). This
Upon finishing the 1,200-m Bronco shuttle sprint, the Soldiers run was hand-timed, then verified with the VX Log. After re-
moved to the range, in which designated range facilitators re- turning to the initial testing site, lactate and salivary osmolal-
cited a scripted safety brief, followed by loading and safety ity tests were performed one final time. Then each donation
demonstrations. Soldiers completed three lanes of both static group participant had their donated blood returned under
and dynamic stress shoot marksmanship tasks while wearing medical provider supervision or was given a sham infusion of
a normal combat load. The stress shoot marksmanship tasks 500mL normal saline. Each participant was asked after each
were completed using their assigned 5.56×45-mm chambered testing session which procedure (blood draw or sham control)
M4A1 carbine assault rifle and 9-mm pistol. they had been subject to on that day. Participants were then re-
leased no earlier than 10 minutes after a successful autologous
At the facilitator’s signal, the Soldiers moved to lane 1 and transfusion of collected blood.
initiated contact with three International Practical Shooting
Confederation (IPSC) silhouette cardboard targets at 40m, Data were recorded on data sheets and entered into a secure
shooting two rounds per target using the rifle. After six rounds, spreadsheet. The VX Log devices were downloaded daily, and
they sprinted to a cone 10m from the targets to shoot at the files were manually analyzed using the corresponding times
same three targets, two shots per target. They then sprinted from the data sheets. Markers were set for each phase includ-
back to the 40m cone to repeat two rounds per target using the ing rest, 1,200-m shuttle run, stress shoot, and distance run.
rifle. Each IPSC target was placed 7m apart from each other. Maximum heart rate and estimated core temperature for each
phase were then exported. Prism 10 (GraphPad Software,
After 24 rounds were shot at lane 1, the Soldiers immediately Boston, MA) was used for all statistical analyses. Dependent
transitioned to lane 2. They ran 20m around the berm and up t tests were used to compare the trials, and Hedges’ g effect
to the 10m cone to shoot four IPSC targets, two shots per tar- size was calculated to provide the magnitude of the differences
get. By the third target, the Soldier’s magazine was empty, and between trials in terms of standard deviation. Magnitude was
they switched to their pistol for the last two targets. Following interpreted where small = 0.2, moderate = 0.6, large = 1.2,
10
completion of these four targets, they ran 25m to a five-target very large = 2.0. A 2×4 condition-by-time RMANOVA was
dueling tree and shot once per target at 10m. After hitting all used to examine heart rate, estimated core temperature, blood
five targets, they ran back to the 50m cone and switched to lactate, and salivary osmolality. For all statistical tests, α was
the rifle, with which they shot two times each IPSC target. set at 0.05.
After the last target was shot, the Soldiers grabbed a 2-handed
rope handle and dragged a 90-lb sled backwards for 25m to Results
the next position. At this position, they shot five times at an
IPSC target from 50m away, quickly moved to a 10m cone, All Soldiers who began the study completed both testing pro-
and then shot three IPSC targets while moving laterally, two tocols, and no adverse events were noted. Blinding was only
shots per target. 26% effective, as Soldiers were able to correctly identify the
procedure that they had been subjected to 74% of the time.
The Soldiers then ran to the third lane and engaged a single There was a moderate-to-large, statistically significant increase
steel target from 50m with their pistol. They shot at the single in shuttle run time due to blood donation (Hedges’ g=1.0; Fig-
steel target until two impacts were made or until their pistol ure 1). We also detected moderate, statistically significant in-
magazine ran out of ammunition. Once one of these condi- creases in shooting scores (Hedges’ g=0.5) and 8-km run times
tions was met, the Soldier ran from the 50m cone to the 25m (Hedges’ g=0.7) due to blood donation (Figures 2 and 3).
cone, where three more steel targets were hit, twice per target.
From the 25m cone, the Soldier ran to the 10m cone and re- FIGURE 1 Estimation plot of individual 1500-m shuttle times
peated the same procedure. Once all targets were shot, the Sol- for control (mean 395.8 s) and blood draw (mean 405.6 s) trials
dier sprinted back to the 40m cone, which marked completion (p=.008, Hedges’ g=1.0).
of the stress shoot test, which was hand timed.

The IPSC targets consisted of A–D scoring zones, which al-
lowed the range facilitator to assess the accuracy of each shot
for scoring. A 1-second and 3-second time penalty was imple-
mented for shots in the C zone and D zone, respectively, while
a 5-second penalty was enforced for shots missed, both on the
IPSC and steel targets. On the dueling tree, a 5-second penalty
was added per target missed. Finally, the Soldier was penal-
ized 5 seconds for not remembering instructions, which were
stated prior to the start of the stress shoot test. The Soldier
then locked and cleared both weapons and left the range for
post-shoot physiological testing.

Distance Run
After the stress shoot, Soldiers were tested for lactate and ∆
salivary osmolality and moved to the last event. Still in their
combat load, they ran from the range where they had just
completed the stress shoot to the initial staging building where
the pre-exercise assessments were performed, then back to the The mean difference was 12.5 seconds between trials.

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