title: "Float first and kick for your life": Psychophysiological basis for safety behaviour on accidental short-term cold water immersion.
abstract: BACKGROUND
  Accidental cold-water immersion (CWI) evokes the life threatening cold shock response (CSR) which increases the risk of drowning. Consequently, the safety behaviour selected is critical in determining survival; the present advice is to 'float first' and remain stationary (i.e. rest). We examined whether leg only exercise (i.e., treading water; 'CWI-Kick') immediately on CWI could reduce the symptoms of the CSR, offset the reduction in cerebral blood flow that is known to occur and reduce the CSR's symptoms of breathlessness. We also examined whether perceptual responses instinctive to accidental CWI were exacerbated by this alternative behaviour. We contrasted CWI-Kick to a 'CWI-Rest' condition and a thermoneutral control (35°C); 'TN-Rest'.
  
  
  METHODS
  Seventeen participants were tested (9 males, 8 females). All immersions were standardised; water temperature in cold conditions (i.e., 12°C) was matched ±/0.5°C within participant. Middle cerebral artery blood flow velocity (MCAv) and cardiorespiratory responses were measured along with thermal perception (sensation and comfort) and dyspnoea. Data were analysed using repeated measures ANOVA (alpha level of 0.05).
  
  
  RESULTS
  MCAv was significantly reduced in CWI-Rest (-6 (9)%; 1st minute of immersion) but was offset by leg only exercise immediately on cold water entry; CWI-Kick MCAv was never different to TN-Rest (-3 (16)% cf. 5 (4)%). All CWI cardiorespiratory and perceptual responses were different to TN-Rest but were not exacerbated by leg only exercise.
  
  
  CONCLUSIONS
  Treading water may aid survival by offsetting the reduction in brain blood flow velocity without changing the instinctive behavioural response (i.e. perceptions). "Float first - and kick for your life" would be a suitable amendment to the water safety advice.
authors.affiliation: Northumbria University, Department of Sport, Exercise and Rehabilitation, Northumberland Building, Northumberland Rd, Newcastle Upon Tyne, UK. Electronic address: martin.barwood@northumbria.ac.uk.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Barwood
authors.affiliation: James Cook University Hospital, Emergency Medicine Unit, Marton Road, Middlesbrough, UK. Electronic address: hburrowz@gmail.com.
authors.forename: Holly
authors.initials: H
authors.lastname: Burrows
authors.affiliation: Northumbria University, Department of Sport, Exercise and Rehabilitation, Northumberland Building, Northumberland Rd, Newcastle Upon Tyne, UK. Electronic address: jess.cessford@northumbria.ac.uk.
authors.forename: Jess
authors.initials: J
authors.lastname: Cessford
authors.affiliation: Northumbria University, Department of Sport, Exercise and Rehabilitation, Northumberland Building, Northumberland Rd, Newcastle Upon Tyne, UK. Electronic address: stuart.goodall@northumbria.ac.uk.
authors.forename: Stuart
authors.initials: S
authors.lastname: Goodall
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply; D003080:Cold Temperature / Q000009:adverse effects; D058639:Cold-Shock Response / Q000502:physiology*; D004417:Dyspnea / Q000175:diagnosis / Q000209:etiology; D004924:Escape Reaction / Q000502:physiology*; D005260:Female; D006801:Humans; D007101:Immersion / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption; D010465:Perception / Q000502:physiology; D011603:Psychophysiology; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water
keywords: Thermal perception; Treading water; Water safety