Page 101 - JSOM Spring 2020

8 weeks of US Army Ranger training reportedly decreased production of testosterone in the Leydig cells of the testes. As
body mass, fat mass, and lean body mass, with reductions in levels of testosterone increase, the levels of testosterone inhibit
field measures of strength and power of 16–21%. However, the release of gonadotropin-releasing hormone, LH, and FSH
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SOF training durations as few as 3 days have been reported to via negative feedback systems.
markedly alter body composition and musculoskeletal function
(Table 1). Synthetic derivatives of testosterone, known as anabolic an-
drogenic steroids (AAS), were developed in East Germany and
Available research on military personnel during SOF training later in the United States. AAS are principally testosterone
focusing on the 72 hours of training exposure shows decreases molecules that have been modified in the 17α-carbon posi-
in LBM, diminished muscular function, and decreased tes- tion, affecting liver metabolism of the compound, as well as
tosterone levels (Table 1). The reductions in testosterone ap- the half-life, potency, and toxicity of the synthetic compound.
pear to be the additive effects of very high physical demand, AAS bind to androgen receptors, stimulate the actions of tes-
reduced caloric intake, a negative caloric balance, and sleep tosterone, and vary in delivery vehicle from oral and transder-
deprivation. Each of these factors has separately been shown mal to injectable forms.
to reduce testosterone. Collectively, the resulting reduction in
functional capacity during SOF training likely occurs during Therapeutic Testosterone Therapy
SUSOPS and may impair mission success and endanger the Exogenous testosterone therapy has shown modest benefits
safety of personnel. It is theorized that use of exogenous tes- in antiaging research as well as in combating type 2 diabetes
tosterone therapy in military personnel during SUSOPS is and Alzheimer disease. Men typically experience reductions
consistent with its use in patients suffering from wasting dis- in testosterone as a function of aging, resulting in low levels
eases or low LBM. During SUSOPS, the effects of physically of LBM, type 2 diabetics normally have not only obesity but
demanding conditions, injury, a negative energy balance, and also lower levels of LBM. In addition, individuals living with
sleep deprivation may be attenuated by the use of supplemen- human immunodeficiency virus (HIV) infection typically have
tal testosterone, which may provide greater likelihood of mis- low testosterone levels and may be treated with testosterone
sion success. to combat fatigue. In the case of HIV-positive patients, it is
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likely that fatigue is at least in part related to decreased LBM
Understanding that SOF’s initial and sustainment training is impairing normal activities of daily living.
physiologically demanding, can the use of testosterone supple-
mentation offset the adverse effects on body composition and Studies investigating the effects of testosterone or AAS on
muscle function experienced throughout an Operator’s career? skeletal muscle function have overwhelming used male sub-
jects. This is due to the potential unwanted androgenic effects
resulting in masculinization in females. Most studies using
Background
exogenous testosterone without the addition of resistance
Testosterone Biochemistry training 19–27 generally used subjects who were older than 40
Testosterone is a steroid (lipid-based) hormone that has both years (mean age 46.3 years) (Table 2). However, male subjects
androgenic and anabolic effects. The anabolic effect of tes- in their 20s to 30s were more commonly studied 28–34 when re-
tosterone is principally the stimulation of protein synthe- sistance training was combined with exogenous testosterone
sis in muscle and bone, whereas the androgenic effects are treatment (Table 3).
the secondary sex characteristics (e.g., body hair, deepening
of the voice, and male reproductive function). The produc- As summarized in Tables 2 and 3, exogenous testosterone or
tion of testosterone is regulated by the hypothalamic-pitu- AAS has been administered for as few as 4 weeks or up to 24
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itary-gonadal (HPG) axis. When testosterone levels are low, months. 19,22 The average dosage used in studies investigating
the hypothalamus releases gonadotropin-releasing hormone, exogenous testosterone treatment was ~250–300mg weekly,
which stimulates the release of luteinizing hormone (LH) and for an average of 35–40 weeks (Tables 2 and 3). Dosages of
follicle-stimulating hormone (FSH). LH and FSH stimulate AAS do not correlate directly with testosterone dosages and

TABLE 1 Effects of Special Operations Training on Lean Body Mass and Muscle Strength
Subjects %Δ
Duration EE EI Energy Sleep %Δ Δ BM %Δ Lower Body
Source Age (y) n (days) (kcal/day) (kcal/day) Balance (h/day) Testosterone (kg) LBM Strength/Power
Nindl 6 22 ± 3 14 3 4,500 1,600 –2,900 3.6 –2.5 –2.3 –6.3
Morgan 11 28.8 ± 5 124 ~3 –43
Gomez-Merino 7 21 ± 2 26 5 3,200 –35
Vaara 8 52 5 –47 –1.6
Aakvaag 22–25 8 6 10,960 1,600 –9,360 2 –84 –4 –8.9
Welsh 24 ± 1 29 8 3,834 1,540 –2,294 NA NA –4.1 –2.4
7,000– 4,000–
Kyröoläinen 24 ± 2 10 5–20 3,000 –4.2 –3.4
3,000 1,000
Friedl 13 96 4,000 2,800 –1,200 3.6 –88 –12.1 –7.3
Friedl 13 96 4,200 3,200 –1,000 3.6 –88 –10 –6.1
Nindl 5 24.6 ± 4.4 50 96 2 –83 –10 –6.1 –20.0
Mean 39.4 5,498.8 2,420 –3,351 3.0 –63 –6.1 –4.6 –11.7
Abbreviations: Δ, change; NA, not available.

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