title: Respiratory Muscle Training and Cognitive Function Exercising at Altitude.
abstract: BACKGROUND
  Hiking and trekking often occur at altitudes up to 12,000 ft altitude. The hypoxia-induced hyperventilation at altitude paradoxically reduces arterial CO2 (Paco2). A reduction in Paco2 results in vasoconstriction of the blood vessels of the brain and thus in local hypoxia. The local hypoxia likely affects cognitive function, which may result in reduced performance and altitude accidents. Recent publications have demonstrated that voluntary isocapnic hyperventilatory training of the respiratory muscles (VIHT) can markedly enhance exercise endurance as it is associated with reduced ventilation and its energy cost. VIHT may be useful in blunting the altitude-induced hyperventilation leading to higher Paco2 and improved cognitive function.
  
  
  METHODS
  This study examined the effects of VIHT, compared to control (C) and placebo (PVIHT) groups, on selected measures of executive functioning, including working memory and processing speed (i.e., Stroop Test, Symbol Digit Modalities Test, and Digit Span Forward) at simulated altitude up to 12,000 ft. Associated physiological parameters were also measured.
  
  
  RESULTS
  The Digit Span Forward Test did not show improvements after VIHT in any group. The VIHT group, but not C or PVIHT groups, improved significantly (17-30%) on the Stroop Test. Similarly the VIHT group, but not the C and PVIHT groups, improved correct responses (26%) and number of attempts (24%) on the Symbol Digit Modalities Test. In addition, reaction time was also improved (16%).
  
  
  CONCLUSIONS
  VIHT improved processing speed and working memory during exercise at altitude.
authors.affiliation: Center for Research and Education in Special Environments, Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Quackenbush
authors.forename: Aubrey
authors.initials: A
authors.lastname: Duquin
authors.forename: Samuel
authors.initials: S
authors.lastname: Helfer
authors.forename: David R
authors.initials: DR
authors.lastname: Pendergast
mesh_terms: D000531:Altitude; D001945:Breathing Exercises; D002560:Cerebrovascular Circulation; D003071:Cognition / Q000502:physiology*; D056344:Executive Function; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic; D009483:Neuropsychological Tests; D010101:Oxygen Consumption / Q000502:physiology; D055815:Young Adult