Page 77 - Journal of Special Operations Medicine - Spring 2014

decreased 83%, which is within the range of a hypo- Sustained operations, ranging from 3-day missions to 8
gonadal male. 16,17 Circulating concentrations of insulin- weeks of training, are consistently described in the sci-
like growth factor 1 (IGF-1) decreased 55%, whereas entific literature as (1) high-energy expenditure, (2) un-
cortisol increased 32%. Additionally, body mass (BM) derfeeding, and (3) sleep deprivation. The combination
decreased 12.6%, fat-free mass (FFM) decreased 6%, of these operational stressors can lead to deleterious ef-
and fat mass (FM) decreased 50%. Absolute changes fects on physical and cognitive performance of Special
in FFM were significantly (although weakly) corre- Operators (Table 1). Body fat composition undergoes
lated with changes in IGF-1 (r = 0.42) and cortisol (r = significant changes following SUSOPS, and the longer
–0.33), but not testosterone (r = 0.22). Similarly, abso- the SUSOPS, the greater is the effect on percent body
lute changes in FM were significantly (although weakly) fat composition. For example, BM has been reported
correlated with changes in IGF-1 (r = –0.30) and cortisol to decrease 3.1% after 72 hours of SUSOPS, 4.1% af-
22
(r = 0.40), but not testosterone (r = –0.20). These results ter 8 days of SUSOPS, and 12.6% after 8 weeks of
23
suggest that changes in IGF-1 and cortisol are better in- Ranger School. Fat-free mass has been reported to
16
dicators of severe weight loss correlating with tissue loss decrease 2.3% after 72 hours of SUSOPS, with losses
during operational stress rather than reductions in tes- of FFM in the arms and trunk only (4–5%). A simi-
22
tosterone. Monitoring circulating levels of endogenous lar 2.4% decrease in FFM was reported after 8 days of
16
hormones in Special Operators during training or dur- SUSOPS, and Ranger students lost 6% of initial FFM
23
ing missions may not be practical. after 8 weeks of training. Significant decrements in
16
FFM were reported in only the arms (12%) and legs
Nonetheless, Nindl et al. found that after several (9%) after Ranger School, differing from the regional
months of high operational stress there were significant losses in FFM after 72 hours of operational stress. 16,22
negative physiological changes that occurred. Friedl et Furthermore, overall FFM decreased 5% after 8 days of
16
al. also studied the effects of “chronic energy deficit” special support and reconnaissance (SSR), and the lower
on endogenous hormone levels throughout the 8-week extremities lost 6% of muscle mass. A 5% decrease in
5
Ranger course. Analogous to the findings of Nindl et FFM after 8 days of SSR and a 6% decrease in FFM
18
al, after 8 weeks of high-stress training, testosterone after 8 weeks of Ranger training depict the effects of
16
decreased 86.5% and IGF-1 decreased 57.1%. Corti- mission duration and differences in types of operational
18
sol increased 60.1%. Friedl et al. reported that energy stress imposed on the human body.
deficit was associated with the significant declines in
testosterone, not exercise. For example, testosterone Whereas SSR units experience immobilization and
18
levels returned to normal during re-feeding despite high- muscle atrophy due to lack of muscular loading, high-
energy expenditures during the training course, which intensity, long-duration training leads to muscle atrophy
averaged 6,000kcal/day. Friedl et al. suggested that ar- most likely attributed to nutritional deficiency, overex-
tificial restoration of hormone levels within the normal ertion, and changes in hormonal levels. Because little
range may be beneficial physiologically and psychologi- can be done to change the reality of SUSOPS, an ap-
cally for Ranger students. 18 propriate nutritional countermeasure may be beneficial
in mitigating or preventing the losses of BM and FFM
Despite the lack of correlation between FFM and testos- during missions. The First Strike Ration is a suggested
®
terone reported by Nindl et al, testosterone and FFM countermeasure for SUSOPS and is designed for use
16
are known to be positively correlated with muscular during repetitive 3- to 7-day missions that also include a
strength. Thus, Nindl et al. suggest the research and recommended recovery period of approximately 1 to 3
19
development of a novel therapeutic agent as a counter- days between missions. This ration should be approxi-
24
measure, which would allow circulating concentrations mately 2,400kcal/day and should include the following
of endogenous growth and anabolic hormones to be macronutrients: 100 to 120g of protein, 350g of carbo-
maintained, thus possibly attenuating losses in FFM. hydrate, and an estimated 58 to 67g of fat.
16
Another recommended countermeasure would be the
prescription of amino acid supplements. For example, Furthermore, it is recommended that a high-carbohydrate
Opstad and Aakvaag found that during a 5-day Ranger supplement (~400kcal or 100g) be added to the First
training course of operational stress, testosterone levels Strike Ration for Operators who require higher energy
did not recover after cadets consumed additional calo- needs. By using this ration, body weight loss during
24
ries primarily from carbohydrates. This suggests that SUSOPS could be attenuated, and it is recommended
20
caloric deficiency is not a contributing factor toward that weight loss be measured after 1 month of using this
lowered testosterone levels and that changes in testos- ration. Erdman et al. recommend that if an Operator’s
terone and IGF-1 may be related to an insufficient in- weight loss is greater than 10%, he should not be sent
take of amino acids. 7,20,21 on assault missions until weight stabilizes within 5% of

Operational Stressors on Physical Performance and Countermeasures 69