Citation

Hart NH, Newton RU. EBioMedicine 2019; ePub(ePub): ePub.

Affiliation

Exercise Medicine Research Institute, Edith Cowan University, Perth, WA, Australia; School of Medical and Health Science, Edith Cowan University, Perth, WA, Australia; School of Exercise and Nutrition Science, University of Queensland, Brisbane, QLD, Australia.

Copyright

(Copyright © 2019, Elsevier Publishing)

DOI

10.1016/j.ebiom.2019.08.015

PMID

31405757

Abstract

Tactical operators, inclusive of soldiers in the military, are reliant upon their physiological and psychological state in often volatile and extreme life or death situations that require correct decisions and precise actions to ensure operational success with minimal collateral damage. Accordingly, the development of physical and mental resilience are hallmarks of prophylactic and remedial programs designed to ensure military personnel are combat ready, thus optimising their capacity to perform at expert levels, while reducing their risk of injury or the severity of injury sustained. Unfortunately, despite best efforts, current practices have not overcome the significant logistical challenges confronting a military service member's routine exposure to moderate and severe energy deficits upon deployment, resulting from unyielding energy demands and restricted energy intake during missions [1]. Consequently, these episodes of semi-starvation under complex and extreme tactical environments produces a cascade of interlinked negative outcomes, including a hypogonadal endocrine state (suppressed testosterone production), loss of muscle-bone mass and strength, reduced functional capacity, compromised cognition, and a suppressed immune system, culminating in greater susceptibility to injury, illness and sub-optimal performance, jeopardising their own welfare and the welfare of their comrades.

Normal physiologic levels of serum testosterone expressed in young men in the United States ranges from 10.4 to 34.7 nmol/L (300 to 1000 ng/dL) [2]. However, military personnel express up to 65% less serum testosterone as a consequence of stress and duress applied in military training [3], reflecting the inevitable response also experienced by deployed military soldiers. To remedy hypogonadal states induced by moderate-to-severe energy deficits and extreme operational conditions, exogenous testosterone supplementation (testosterone replacement therapy) is a viable countermeasure to effectively reverse the cascade of physical and mental consequences experienced by tactical operators [4]. In alignment with clinical treatment of men with chronically low testosterone levels, the updated Endocrine Society clinical practice guidelines recommend a wide array of pharmacotherapies, the most prominent of which is testosterone enanthate; an easily administered synthetic derivative of testosterone through intramuscular injection; to be given at a starting rate of 75–100 mg/week on average [2]. Such strategies in the hypogonadal civilian have been shown to produce predictable yet important benefits, such as increased myogenesis and osteogenesis (muscle-bone mass and strength), improved physical function, reduced anxiety, increased mood, and increased cognition (i.e. attention, visual scanning ability, executive function and psychomotor speed) [5,6]. These qualities are critical to the performance of military personnel, though whether testosterone replacement produces equivalent outcomes under moderate-to-severe energy deficits as a consequence of extreme operational conditions has yet to be clarified...

Language: en

Keywords

Bone; Endocrine; Endurance; Function; Muscle; Resilience; Strength