Physical performance responses during 72 h of military operational stress

Med Sci Sports Exerc. 2002 Nov;34(11):1814-22. doi: 10.1097/00005768-200211000-00019.


Purpose: To characterize the impact of prolonged work, underfeeding, and sleep deprivation (i.e., sustained operations; SUSOPS) on physical and occupational related performance during military operational stress.

Methods: Ten male soldiers were tested on days 1 (D1), 3 (D3), and 4 (D4) of a control and an experimental week that included prolonged physical work (total daily energy expenditure approximately 4,500 kcal x d(-1)), underfeeding (approximately 1,600 kcal x d(-1)), and sleep deprivation (approximately 2 h x d(-1)). Body composition was measured with dual-energy x-ray absorptiometry (DEXA). Ballistic power was assessed by 30 repetitive squat jumps and bench-press throws. Military-relevant occupational performance was evaluated with a 10-min box lift, obstacle course, grenade throw, rifle marksmanship, and a 25-min wall-build task.

Results: Fat-free mass (-2.3%) and fat mass (-7.3%) declined (P </= 0.05) during SUSOPS. Squat-jump mean power (-9%) and total work (-15%) declined (P </= 0.05) during SUSOPS. Bench-press power output, grenade throw, and marksmanship for pop-up targets were not affected. Obstacle course and box-lift performances were lower (P </= 0.05) on D3 but showed some recovery on D4. Wall building was approximately 25% lower (P </= 0.05) during SUSOPS.

Conclusion: Decrements in performance during SUSOPS are primarily restricted to tasks that recruit muscles that are over-utilized without adequate recovery. General military skill tasks and occupational physical performance tasks are fairly well maintained.

Publication types

  • Clinical Trial
  • Comparative Study

MeSH terms

  • Adaptation, Physiological
  • Adult
  • Analysis of Variance
  • Body Composition
  • Body Weight
  • Humans
  • Male
  • Military Personnel*
  • Occupations
  • Physical Endurance / physiology*
  • Physical Exertion
  • Probability
  • Reference Values
  • Risk Assessment
  • Sampling Studies
  • Stress, Physiological* / physiopathology*
  • Task Performance and Analysis