title: Cold-water face immersion per se elicits cardiac parasympathetic activity.
abstract: BACKGROUND
  Cold-water face immersion (FI) is known to produce physiological changes, including bradycardia, by stimulating the parasympathetic system. However, other factors such as sympathetic activity, intrapleural pressures, and changes in chemical mediators may also contribute to these changes.
  
  
  RESULTS
  Eight healthy volunteers underwent a series of experiments designed to observe the effects of FI on heart rate and its variability, as detected using wavelet transformation. Each subject was instructed to bend over and put the entire face into an empty basin with and without breathing (protocols 1 and 2, respectively), and then perform FI in warm-water (protocols 3 and 4, respectively) and cold-water (protocols 5 and 6, respectively) while breathing and breath holding. Change in the R-R interval with FI was only significantly greater for protocol 6 than for the control procedure (protocol 1). Also, changes in the natural logarithm of high-frequency power with FI were significantly greater for protocols 5 and 6 than the protocol 1.
  
  
  CONCLUSIONS
  Bradycardia associated with cold-water FI is mainly attributed to cardiac vagal activity, which is independent of both the change in body position caused by bending over a basin and breath holding.
authors.affiliation: Department of Paediatrics/Developmental Paediatrics, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kinoshita
authors.forename: Shinya
authors.initials: S
authors.lastname: Nagata
authors.forename: Reizo
authors.initials: R
authors.lastname: Baba
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kohmoto
authors.forename: Suketsune
authors.initials: S
authors.lastname: Iwagaki
mesh_terms: D000328:Adult; D001919:Bradycardia; D003080:Cold Temperature; D005145:Face / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007101:Immersion; D008297:Male; D013697:Thermosensing / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology*; D014867:Water
chemical_list: D014867:Water