Habituation of the cold shock response: a systematic review and meta-analysis

Martin J. Barwood, Clare Eglin, Samuel P. Hills, Nicola Johnston, Heather Massey, Terry McMorris, Michael J. Tipton, Hitoshi Wakabayashi, Lisa Webster

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Abstract

Cold water immersion (CWI) evokes the life-threatening reflex cold shock response (CSR), inducing hyperventilation, increasing cardiac arrhythmias, and increasing drowning risk by impairing safety behaviour. Repeated CWI induces CSR habituation (i.e., diminishing response with same stimulus magnitude) after ∼4 immersions, with variation between studies. We quantified the magnitude and coefficient of variation (CoV) in the CSR in a systematic review and meta-analysis with search terms entered to Medline, SportDiscus, PsychINFO, Pubmed, and Cochrane Central Register. Random effects meta-analyses, including effect sizes (Cohen's d) from 17 eligible groups (k), were conducted for heart rate (HR, n = 145, k = 17), respiratory frequency (fR, n = 73, k = 12), minute ventilation (Ve, n = 106, k = 10) and tidal volume (Vt, n = 46, k=6). All CSR variables habituated (p < 0.001) with large or moderate pooled effect sizes: ΔHR -14 (10) bt. min−1 (d: −1.19); ΔfR −8 (7) br. min−1 (d: −0.78); ΔVe, −21.3 (9.8) L. min−1 (d: −1.64); ΔVt −0.4 (0.3) L −1. Variation was greatest in Ve (control vs comparator immersion: 32.5&24.7%) compared to Vt (11.8&12.1%). Repeated CWI induces CSR habituation potentially reducing drowning risk. We consider the neurophysiological and behavioural consequences.
Original languageEnglish
Article number103775
Number of pages16
JournalJournal of Thermal Biology
Volume119
Early online date27 Dec 2023
DOIs
Publication statusPublished - 1 Jan 2024

Keywords

  • Drowning risk
  • Cold shock response
  • Non-fatal drowning
  • Immersion
  • Safety behaviour
  • Sensitisation
  • Psychophysiology

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