Trial of Testosterone Undecanoate for Optimizing Performance During Military Operations

The objective of this study is to determine the effects of a single dose of testosterone undecanoate during and in recovery from simulated operational stress.

This is a double-blind, randomized, placebo controlled trial in 32 physically active men exposed to 20 complete days (days 8-27) of simulated operational stress followed by 20 complete days of recovery (days 29-48). After completing baseline testing (Phase 1), participants will be randomized to receive either a single intramuscular injection of testosterone undecanoate or an isovolumetric placebo (Day 8). The 20-day simulated operational stress (Phase 2) will be highly controlled (live-in study) and consist of 4 successive cycles of undulating stress, starting with 2 consecutive days of low stress followed by 3 consecutive days of high stress. Low- and high-stress days will result from low and high militarily-relevant exercise-induced energy expenditures, adequate and restricted sleep (8 hours vs. 4 hours daily), and diet restriction to produce energy deficits. After completing Phase 2, participants will be released to resume their habitual physical activity routines and will be provided a controlled diet to consume (Phase 3), to assess recovery from sustained, severe operational stress.

Eligibility Criteria:
Inclusion Criteria:

* Men aged 18-35 years
* Ability to understand verbal or written instructions/testing materials in English
* Physically active (as determined by accelerometry and review of a physical activity log)
* Not taking any prescription medications and/or willing to refrain from all medication use prior to and throughout the entire study period, unless provided/approved by the study physician
* Willing to refrain from alcohol, smoking, e-cigarettes or use of any nicotine product, caffeine, and dietary supplement use throughout the entire study period
* Willing to live on the Pennington Biomedical Research Center inpatient unit for 20 consecutive days
* Meets age-specific US Army body composition standards according to Army Regulation 600-9, which includes estimates of percent body fat based on height, weight, and circumference measures (neck and waist)
* Total testosterone concentration is within the normal physiological range (300-1,000 ng/dL)

Exclusion Criteria:

* Musculoskeletal injuries that compromise exercise capability
* Diagnosed cardiometabolic disorders (i.e., hypertension, hyperlipidemia, kidney disease, diabetes, etc.)
* Allergies or intolerance to foods, vegetarian practices, or history of complications with lidocaine
* Anabolic steroid, human growth hormone, or nutritional testosterone precursor-like supplement use within the past 6 months
* Will not refrain from smoking (any nicotine product), alcohol, caffeine, or any other dietary supplement during the study
* Adults unable to consent
* Women
* Prisoners
* Sedentary or engages in insufficient quantities of physical activity per week (aerobic and/or resistance training as determined by accelerometry and review of a physical activity log)
* Exceeds age-specific US Army body composition standards according to Army Regulation 600-9
* Previous history of kidney stones unless otherwise approved by the medical investigator
* Systolic blood pressure \> 150 or diastolic blood pressure \> 95 mmHg
* Previous history of breast or prostate cancer
* Previous history of Chronic Obstructive Pulmonary Disease or Obstructive Sleep Apnea
* Prostate-Specific Antigen (PSA) \> 3ng/ml, Hematocrit \> 50%, or positive urine drug screening
* Based on the investigative team's clinical judgment, a subject may not be appropriate for participation in the study