title: The effects of movement and physical exertion on soldier vigilance.
abstract: BACKGROUND
  The effects of movement and physical exertion on cognitive processes remain unclear. Some studies report improvements in information processing while others report decrements or no change. To address relationships between movement, physical exertion, and cognitive performance, vigilance performance while soldiers walked with a heavy (40 kg) load was examined.
  
  
  METHODS
  Volunteers (n = 18) completed six 30-min test sessions on separate days: standing; walking with or without obstacles; while carrying a 40-kg load or no load. Suprathreshold visual, auditory or tactile stimuli were presented during the vigilance task. Dependent measures included accuracy, response time and distance traversed.
  
  
  RESULTS
  Volunteers reported higher perceived exertion (p < 0.05) when carrying a load and these ratings increased with time (p < 0.05). There were fewer correct responses on the vigilance task when carrying a load (p < 0.05) or when walking over obstacles (p < 0.05). Vigilance performance was superior with auditory compared with visual or tactile stimuli (p < 0.05). Less distance was covered when carrying a load (p < 0.05), traversing the course with obstacles (p < 0.05), and when responding to a tactile, compared with an auditory, stimulus (p < 0.05).
  
  
  CONCLUSIONS
  These results indicate walking around obstacles and the exertion of load carriage affect performance on the basic cognitive function of vigilance. Furthermore, they raise fundamental questions about whether cognitive performance data collected from sedentary, rested volunteers are applicable to individuals, including dismounted soldiers, engaged in tasks that concurrently require physical and cognitive resources.
authors.affiliation: U.S. Army Soldier Center, AMSRD-NSC-SS-P, Natick, MA 01760-5020, USA. caroline.mahoney@natick.army.mil
authors.forename: Caroline R
authors.initials: CR
authors.lastname: Mahoney
authors.forename: Edward
authors.initials: E
authors.lastname: Hirsch
authors.forename: Leif
authors.initials: L
authors.lastname: Hasselquist
authors.forename: Larry L
authors.initials: LL
authors.lastname: Lesher
authors.forename: Harris R
authors.initials: HR
authors.lastname: Lieberman
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D006801:Humans; D008297:Male; D008887:Military Medicine; D008889:Military Personnel; D009068:Movement / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D011795:Surveys and Questionnaires; D013647:Task Performance and Analysis; D016474:Weight-Bearing / Q000502:physiology