title: Habituation of the cold shock response may include a significant perceptual component.
abstract: BACKGROUND
  Accidental immersion in cold water is a risk factor for many occupations. Habituation to cold-water immersion (CWI) is one practical means of reducing the cold shock response (CSR) on immersion. We investigated whether repeated thermoneutral water immersion (TWI) induced a perceptual habituation (i.e., could lessen perceived threat and anxiety) and consequently reduce the CSR on subsequent CWI.
  
  
  METHODS
  There were 12 subjects who completed seven 7-min head-out immersions. Immersions one and seven were CWls [15.0 (0.1) degrees C], and immersions two to six were TWI [34.9 (0.10) degrees C]. Anxiety 120-cm visual analogue scale) and the cardiorespiratory responses [heart rate (f(C)), respiratory frequency (f(R)), tidal volume (V(T)), and minute ventilation (V(E))] to immersion were measured throughout. Data were compared within subject between conditions using ANOVA to an alpha level of 0.05.
  
  
  RESULTS
  Acute anxiety was significantly reduced after repeated exposure to the immersion scenario (i.e., TWI): CWI-1: 6.3 (4.4) cm; and CWI-2: 4.5 (4.0) cm [condition mean (SD)]. These differences did not influence the peak in the CSR. The f(C), f(R), and V(E) responses were similar between CWI-1 and CWI-2. V(T) response was significantly lower in CWI-2; mean (SD) across the immersion: CWI-1 1.27 (0.17) vs. CWI-2 1.11 0.21 L.
  
  
  CONCLUSIONS
  Repeated TWI lessened the anxiety associated with CWI (perceptual habituation). This had a negligible effect on the primary components of the CSR, but did lower VT, which may reduce the volume of any aspirated water in an emergency situation. Reducing the threat appraisal of an environmental stressor may be a useful biproduct of survival training, thereby minimizing psychophysiological strain.
authors.affiliation: University of Portsmouth, Department of Sport and Exercise Science, Portsmouth, UK. martin.barwood@port.ac.uk
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Barwood
authors.affiliation: University of Portsmouth, Department of Sport and Exercise Science, Portsmouth, UK.
authors.forename: Jo
authors.initials: J
authors.lastname: Corbett
authors.affiliation: University of Portsmouth, Department of Sport and Exercise Science, Portsmouth, UK.
authors.forename: Christopher R D
authors.initials: CR
authors.lastname: Wagstaff
mesh_terms: D000328:Adult; D001007:Anxiety / Q000503:physiopathology*; D003080:Cold Temperature; D058639:Cold-Shock Response; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D007101:Immersion / Q000503:physiopathology*; D008297:Male; D010465:Perception; D012123:Pulmonary Ventilation; D056152:Respiratory Rate; D013990:Tidal Volume; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water