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.
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.