title: The effect of water immersion during exercise on cerebral blood flow.
abstract: BACKGROUND
  Regular exercise induces recurrent increases in cerebrovascular perfusion. In peripheral arteries, such episodic increases in perfusion are responsible for improvement in arterial function and health. We examined the hypothesis that exercise during immersion augments cerebral blood flow velocity compared with intensity-matched land-based exercise.
  
  
  METHODS
  Fifteen normotensive participants were recruited (26 ± 4 yr, 24.3 ± 1.9 kg·m). We continuously assessed mean arterial blood pressure, HR, stroke volume, oxygen consumption, and blood flow velocities through the middle and posterior cerebral arteries before, during, and after 20-min bouts of water- and land-based stepping exercise of matched intensity. The order in which the exercise conditions were performed was randomized between subjects. Water-based exercise was performed in 30°C water to the level of the right atrium.
  
  
  RESULTS
  The water- and land-based exercise bouts were closely matched for oxygen consumption (13.3 mL·kg·min (95% confidence interval (CI), 12.2-14.6) vs 13.5 mL·kg·min (95% CI, 12.1-14.8), P = 0.89) and HR (95 bpm (95% CI, 90-101) vs 96 bpm (95% CI, 91-102), P = 0.65). Compared with land-based exercise, water-based exercise induced an increase in middle cerebral artery blood flow velocity (74 cm·s (95% CI, 66-81) vs 67 cm·s (95% CI, 60-74) P < 0.001), posterior cerebral artery blood flow velocity (47 cm·s (95% CI, 40-53) vs 43 cm·s (95% CI, 37-49), P < 0.001), mean arterial blood pressure (106 mm Hg (95% CI, 100-111) vs 101 mm Hg (95% CI, 95-106), P < 0.001), and partial pressure of expired CO2 (P ≤ 0.001).
  
  
  CONCLUSIONS
  Our findings suggest that water-based exercise augments cerebral blood flow, relative to land-based exercise of similar intensity, in healthy humans.
authors: 1School of Sport Science, Exercise and Health, University of Western Australia, Crawley, Western Australia, AUSTRALIA; 2Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM; 3Graduate School of Health Science, Kobe University, Hyogo Prefecture, JAPAN; and 4Radboud University Medical Center, Nijmegen, NETHERLANDS.
authors: Christopher J A
authors: CJ
authors: Pugh
authors: Victoria S
authors: VS
authors: Sprung
authors: Kumiko
authors: K
authors: Ono
authors: Angela L
authors: AL
authors: Spence
authors: Dick H J
authors: DH
authors: Thijssen
authors: Howard H
authors: HH
authors: Carter
authors: Daniel J
authors: DJ
authors: Green
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000502:physiology; D002560:Cerebrovascular Circulation; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate; D006801:Humans; D007101:Immersion; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology; D010101:Oxygen Consumption; D020769:Posterior Cerebral Artery / Q000502:physiology; D012119:Respiration; D013318:Stroke Volume; D014867:Water; D055815:Young Adult
chemical_list: D014867:Water; D002245:Carbon Dioxide