Page 59 - Journal of Special Operations Medicine - Winter 2015

on body weight as outlined in position papers and fact training or missions occurring above moderate altitude
sheets disseminated by AND, ACSM, USOC, USARIEM and consume adequate calories with a focus on carbo-
and other organizations that provide evidence-based re- hydrate- and protein-rich foods while at altitude. After
sources. Due to the large individual variability in ab- as little as 2 days at altitude, iron stores decrease as the
sorption, distribution, metabolism, and excretion, body increases production of red blood cells. While the
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Special Operators should monitor their own responses current, predominantly male, SOF population has a low
and sensitivities to caffeine intake to minimize sleep potential for anemia, the incidence of iron deficiency is
disturbances. not completely absent in young, healthy men. 93,94 With-
out sufficient iron stores, hypoxia-induced red blood
Arduous environment preparedness cell production could be compromised, resulting in de-
The reality of the Special Operator is that they must per- creased aerobic capacity. Therefore, medical providers
form optimally in the most arduous of environments. should test for serum ferritin, a protein that helps store
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Special Operations occurring in temperature and atmo- iron and is a marker for iron deficiency, in Special Op-
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spheric extremes, under stress and with abnormal sleep/ erators 8–10 weeks prior to training or missions occur-
wake patterns present additional nutrition-related chal- ring at or above moderate altitude. Medical providers
lenges to SOF. should provide referrals for nutrition counseling and
prescribe supplemental iron as indicated by test results.
Various temperature and atmospheric extremes have
been shown to negatively impact military task-specific Special Operations training can evoke a physiological
performance. 82,83 A Special Operator’s ability to ther- stress response. Cognitive decrements from baseline
moregulate is directly impacted by his hydration sta- induced by combat-like stress during an Army Ranger
tus. Both hot and cold environments increase the risk training event and during a Navy SEAL “hell week”
of dehydration. In hot environments, sweat loss and have been reported to be greater than those seen in in-
insensible water loss through respiration and the skin dividuals experiencing clinical hypoglycemia and those
contribute to dehydration and can be exacerbated by with a blood alcohol level qualifying as legally drunk.
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thermal stress of body armor and water immersion. Cortisol, a hormone produced during demanding physi-
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In cold environments, cold-induced diuresis, decreased cal and mental tasks and used to measure physiological
thirst mechanism, and the inconvenience of drinking stress, helps fuel the body’s response to these stressors
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and urinating contribute to dehydration. Although not by breaking down carbohydrate, fat, and protein, and
conclusive, caloric requirements in cold and hot envi- by suppressing the immune system. Although beneficial
ronments may be increased substantially above those in the short term, data have shown a strong relationship
in temperate environments. Substrates used for fuel of sustained elevated cortisol levels with a drop in task-
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during shivering depend on prior nutritional status and specific performance, which appears to be exacerbated
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intensity of shivering, further emphasizing the need for in individuals with higher body-fat percentage. A de-
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balanced macronutrient intake in Special Operators. crease in performance is concerning, since cortisol has
been shown to be elevated during typical training tasks
At and above moderate altitude (2,000–3,000m), the such as hand-to-hand fighting, shooting, skydiv-
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human body compensates for hypoxia by increasing ing, and scuba diving. 102,103 Common training and
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respiration rate, decreasing plasma volume (through combat conditions that result in sleep and food depriva-
diuresis), and decreasing skeletal muscle oxidation. tion, 104,105 circadian misalignment, and survival anxi-
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Higher respiration rates, increased urine output, and ety are also associated with a rise in cortisol levels.
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decreased thirst can contribute to dehydration at alti- Realistic training scenarios using stress inoculation fa-
tude, making the monitoring of fluid consumption im- cilitate Special Operators’ adaptation to these stressful
portant for performance. Disagreement exists regarding events with potential blunting of the stress response ;
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the nutritional significance of a hypoxia-induced reduc- however, studies have shown that even in experienced
tion of skeletal muscle fatty acid oxidation, particularly individuals, cortisol levels will increase when exposed to
at altitude relative workloads. 89,90 However, at absolute these tasks and/or conditions. 101,103,107 Time-dependent
workloads relative to sea level, the increase in glucose consumption of carbohydrate and protein has been
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oxidation and decrease in fatty acid oxidation supports shown to decrease cortisol levels resulting from stress-
pre-altitude glycogen optimization and provision of ful events, and may provide a nutritional strategy for
adequate carbohydrates to fuel activity during altitude preserving performance. Therefore, Special Operators
exposure. In addition to carbohydrates, total energy should consume mixed carbohydrate and protein snacks
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and protein intake must also be monitored to lessen during stressful events, as feasible.
the loss of lean body mass typically seen at higher alti-
tudes. For these reasons, Special Operators should re- Circadian misalignment occurs when normal daily activ-
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frain from low-carbohydrate diets in the weeks prior to ities such as sleep, wake, eat, drink, work, and exercise/
Comprehensive Performance Nutrition for SOF 47