title: The effects of cold and lower body negative pressure on cardiovascular homeostasis.
abstract: OBJECTIVE
  The purpose of this study is to determine how cold exposure and lower body negative pressure effected cardiovascular variables.
  
  
  METHODS
  Eleven males (20.3 years ± 2.7) underwent two 20-minute exposures to LBNP. During the 2 trials, the subjects were exposed to cold air (10°C) (COLD) and to ambient temperature (23°C) (AMB). The trials consisted of a 100-minute pre-LBNP period followed by a 20-minute exposure to LBNP and then a 15-minute recovery period. Cardiovascular variables were recorded every 30 minutes using bioimpedance.
  
  
  RESULTS
  When LBNP was applied during the AMB trials, stroke volume immediately decreased. During the COLD trial, there was a five-minute delay before the decrease in stroke volume. Heart rate increased immediately after LBNP initiation during the AMB trials but there was a delay in the increase during the COLD trials. That same pattern was followed with mean arterial blood pressures. Cerebral oxygenation was significantly lower throughout the COLD trial as compared to the AMB trials. Six subjects reported symptoms of syncope or presyncope during the AMB trials but there were no reports of symptoms during the COLD trials.
  
  
  CONCLUSIONS
  From analysis of this data, cold improved the subject's tolerance to LBNP.
authors: Exercise and Environmental Physiology Laboratory, Kent State University, Kent, OH 44242, USA ; Department of Kinesiology, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA.
authors: David J
authors: DJ
authors: Kean
authors: Exercise and Environmental Physiology Laboratory, Kent State University, Kent, OH 44242, USA ; Farquhar College of Arts and Sciences, Nova Southeastern University, Fort Lauderdale-Davie, FL 33314, USA.
authors: Corey A
authors: CA
authors: Peacock
authors: Exercise and Environmental Physiology Laboratory, Kent State University, Kent, OH 44242, USA ; Department of Kinesiology and Health, Northern Kentucky University, Highland Heights, KY 41099, USA.
authors: Gabriel J
authors: GJ
authors: Sanders
authors: Exercise and Environmental Physiology Laboratory, Kent State University, Kent, OH 44242, USA.
authors: John
authors: J
authors: McDaniel
authors: Department of Kinesiology, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209, USA.
authors: Lisa A C
authors: LA
authors: Colvin
authors: Exercise and Environmental Physiology Laboratory, Kent State University, Kent, OH 44242, USA.
authors: Ellen L
authors: EL
authors: Glickman
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002319:Cardiovascular System / Q000378:metabolism / Q000473:pathology*; D003080:Cold Temperature; D006339:Heart Rate; D006706:Homeostasis; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D013318:Stroke Volume; D013575:Syncope / Q000503:physiopathology