title: Influence of cold water immersion on limb and cutaneous blood flow at rest.
abstract: BACKGROUND
  Cold water immersion reduces exercise-induced muscle damage. Benefits may partly arise from a decline in limb blood flow; however, no study has comprehensively investigated the influence of different degrees of cooling undertaken via cold water immersion on limb blood flow responses.
  
  
  OBJECTIVE
  To determine the influence of cold (8°C) and cool (22°C) water immersion on lower limb and cutaneous blood flow.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Nine men were placed in a semireclined position and lowered into 8°C or 22°C water to the iliac crest for two 5-minute periods interspersed with 2 minutes of nonimmersion. Rectal and thigh skin temperature, deep and superficial muscle temperature, heart rate, mean arterial pressure, thigh cutaneous blood velocity (laser Doppler), and superficial femoral artery blood flow (duplex ultrasound) were measured during immersion and for 30 minutes after immersion. Indices of vascular conductance were calculated (flux and blood flow/mean arterial pressure).
  
  
  RESULTS
  Reductions in rectal temperature (8°C, 0.2° ± 0.1°C; 22°C, 0.1° ± 0.1°C) and thigh skin temperature (8°C, 6.2° ± 0.5°C; 22°C, 3.2° ± 0.2°C) were greater in 8°C water than in 22°C (P < .01). Femoral artery conductance was reduced to a similar extent immediately after immersion (~30%) and 30 minutes after immersion (~40%) under both conditions (P < .01). In contrast, there was less thigh cutaneous vasoconstriction during and after immersion in 8°C water compared with 22°C (P = .01).
  
  
  CONCLUSIONS
  These data suggest that immersion at both temperatures resulted in similar whole limb blood flow but, paradoxically, more blood was distributed to the skin in the colder water. This suggests that colder temperatures may be associated with reduced muscle blood flow, which could provide an explanation for the benefits of cold water immersion in alleviating exercise-induced muscle damage in sports and athletic contexts.
  
  
  CONCLUSIONS
  Colder water temperatures may be more effective in the treatment of exercise-induced muscle damage and injury rehabilitation because of greater reductions in muscle blood flow.
authors.affiliation: Warren Gregson, Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool L3 3AF UK. W.Gregson@ljmu.ac.uk
authors.forename: Warren
authors.initials: W
authors.lastname: Gregson
authors.forename: Mark A
authors.initials: MA
authors.lastname: Black
authors.forename: Helen
authors.initials: H
authors.lastname: Jones
authors.forename: Jordon
authors.initials: J
authors.lastname: Milson
authors.forename: James
authors.initials: J
authors.lastname: Morton
authors.forename: Brian
authors.initials: B
authors.lastname: Dawson
authors.forename: Greg
authors.initials: G
authors.lastname: Atkinson
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Green
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000628:therapy; D001794:Blood Pressure; D001833:Body Temperature Regulation; D003080:Cold Temperature; D017679:Cryotherapy; D005263:Femoral Artery / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D007101:Immersion; D017078:Laser-Doppler Flowmetry; D007866:Leg / Q000098:blood supply; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply*; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply*; D055815:Young Adult