title: Cold-Water Immersion for Hyperthermic Humans Wearing American Football Uniforms.
abstract: BACKGROUND
  Current treatment recommendations for American football players with exertional heatstroke are to remove clothing and equipment and immerse the body in cold water. It is unknown if wearing a full American football uniform during cold-water immersion (CWI) impairs rectal temperature (Trec) cooling or exacerbates hypothermic afterdrop.
  
  
  OBJECTIVE
  To determine the time to cool Trec from 39.5°C to 38.0°C while participants wore a full American football uniform or control uniform during CWI and to determine the uniform's effect on Trec recovery postimmersion.
  
  
  METHODS
  Crossover study.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  A total of 18 hydrated, physically active, unacclimated men (age = 22 ± 3 years, height = 178.8 ± 6.8 cm, mass = 82.3 ± 12.6 kg, body fat = 13% ± 4%, body surface area = 2.0 ± 0.2 m(2)).
  
  
  METHODS
  Participants wore the control uniform (undergarments, shorts, crew socks, tennis shoes) or full uniform (control plus T-shirt; tennis shoes; jersey; game pants; padding over knees, thighs, and tailbone; helmet; and shoulder pads). They exercised (temperature approximately 40°C, relative humidity approximately 35%) until Trec reached 39.5°C. They removed their T-shirts and shoes and were then immersed in water (approximately 10°C) while wearing each uniform configuration; time to cool Trec to 38.0°C (in minutes) was recorded. We measured Trec (°C) every 5 minutes for 30 minutes after immersion.
  
  
  METHODS
  Time to cool from 39.5°C to 38.0°C and Trec.
  
  
  RESULTS
  The Trec cooled to 38.0°C in 6.19 ± 2.02 minutes in full uniform and 8.49 ± 4.78 minutes in control uniform (t17 = -2.1, P = .03; effect size = 0.48) corresponding to cooling rates of 0.28°C·min(-1) ± 0.12°C·min(-1) in full uniform and 0.23°C·min(-1) ± 0.11°C·min(-1) in control uniform (t17 = 1.6, P = .07, effect size = 0.44). The Trec postimmersion recovery did not differ between conditions over time (F1,17 = 0.6, P = .59).
  
  
  CONCLUSIONS
  We speculate that higher skin temperatures before CWI, less shivering, and greater conductive cooling explained the faster cooling in full uniform. Cooling rates were considered ideal when the full uniform was worn during CWI, and wearing the full uniform did not cause a greater postimmersion hypothermic afterdrop. Clinicians may immerse football athletes with hyperthermia wearing a full uniform without concern for negatively affecting body-core cooling.
authors.affiliation: School of Rehabilitation and Medical Sciences, Central Michigan University, Mount Pleasant.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Miller
authors.affiliation: Department of Kinesiology, University of New Hampshire, Durham.
authors.forename: Erik E
authors.initials: EE
authors.lastname: Swartz
authors.affiliation: School of Rehabilitation and Medical Sciences, Central Michigan University, Mount Pleasant.
authors.forename: Blaine C
authors.initials: BC
authors.lastname: Long
mesh_terms: D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology; D003020:Clothing; D003080:Cold Temperature; D018592:Cross-Over Studies; D017679:Cryotherapy / Q000379:methods*; D015444:Exercise / Q000502:physiology; D005334:Fever / Q000628:therapy*; D005538:Football / Q000502:physiology*; D018883:Heat Stroke / Q000503:physiopathology / Q000628:therapy; D006358:Hot Temperature; D006801:Humans; D007101:Immersion / Q000503:physiopathology*; D008297:Male; D012881:Skin Temperature / Q000502:physiology; D014481:United States; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water
keywords: heatstroke; rectal temperature; whole-body immersion