Journal articles: 'Thermoneutral immersion'

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Knight, D. R., and S. M. Horvath. "Urinary responses to cold temperature during water immersion." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 248, no. 5 (May 1, 1985): R560—R566. http://dx.doi.org/10.1152/ajpregu.1985.248.5.r560.

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If cold temperature combines with ambient water pressure to stimulate the Henry-Gauer reflex in humans, then free water clearance (CH2O) should be greater during immersion in cold water (29.8 degrees C) than during exposure to cold air (14.8 degrees C) or immersion in thermoneutral water (35 degrees C). Urinary responses to these environments were compared with control measurements made during 6 h of sitting in thermoneutral air (27.6 degrees C). CH2O was not significantly greater in cold water than in the other environments. Rather, the diuretic response was characterized by an increased osmolar clearance (P less than 0.05). Cold temperature and water pressure additively raised urinary output during cold water immersion, with ambient water pressure accounting for two-thirds of the urinary water loss. An elevated rate of sodium excretion (P less than 0.05) began significantly earlier in cold water than in thermoneutral water. This effect of low temperature might have resulted from cold-induced vasoconstriction, since cold temperatures was observed to reduce the foot volume. Sodium excretion was inversely proportional to vital capacity, indicating a responsiveness of the kidney to expansion of the central blood volume. In addition to the effects of water pressure and cold temperature, urinary function was also sensitive to time. The rate of potassium excretion was significantly elevated at min 199 of exposure to all environments. Failure of CH2O to increase above control values indicated that the human diuretic response to cold water immersion is atypical for the Henry-Gauer reflex.

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Boldt, Leif-Hendrik, Waltraud Fraszl, Lothar Röcker, Jörg Christian Schefold, Mathias Steinach, Thilo Noack, and Hanns-Christian Gunga. "Changes in the haemostatic system after thermoneutral and hyperthermic water immersion." European Journal of Applied Physiology 102, no. 5 (November 28, 2007): 547–54. http://dx.doi.org/10.1007/s00421-007-0620-7.

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Hope, Arvid, Leif Aanderud, and Asbjørn Aakvaag. "Dehydration and body fluid-regulating hormones during sweating in warm (38°C) fresh- and seawater immersion." Journal of Applied Physiology 91, no. 4 (October 1, 2001): 1529–34. http://dx.doi.org/10.1152/jappl.2001.91.4.1529.

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Body weight (BW) reductions of more than 4 kg have been observed during diving with the open hot water suit, a technique in which heated seawater (SW) continuously floods the skin surface. To test the hypothesis that osmotic effects may be involved in these fluid-loss processes, head-out immersion experiments in 38°C freshwater (FW) and SW for 4 h were performed. Average BW reduction was 2.5 and 1.9 kg in SW and FW head-out immersion, respectively ( P < 0.01). Atrial natriuretic peptide increased during the first 30 min of SW immersion (5.6–13.4 pmol/l, P < 0.01) followed by a reduction to 7.6 pmol/l ( P < 0.01). This paralleled an initial decrease in aldosterone (from 427 to 306 pmol/l, P < 0.05) followed by an increase to 843 pmol/l ( P < 0.01). The effects of temperature on fluid loss were studied in thermoneutral (34.5°C) and 38°C SW for 2 h. In thermoneutral SW, calculated sweat production was negligible (0.05 kg) compared with 1.2 kg in warm SW. We recommend that, if a dive is planned to last for more than 4 h, a mandatory break for fluid intake should be incorporated in the diving regulations.

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Gaustad, Svein Erik, Alf O. Brubakk, Morten Høydal, Daniele Catalucci, Gianluigi Condorelli, Zeljko Dujic, Jasna Marinovic, Marko Ljubkovic, Andreas Møllerløkken, and Ulrik Wisløff. "Immersion before dry simulated dive reduces cardiomyocyte function and increases mortality after decompression." Journal of Applied Physiology 109, no. 3 (September 2010): 752–57. http://dx.doi.org/10.1152/japplphysiol.01257.2009.

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Diving and decompression performed under immersed conditions have been shown to reduce cardiac function. The mechanisms for these changes are not known. The effect of immersion before a simulated hyperbaric dive on cardiomyocyte function was studied. Twenty-three rats were assigned to four groups: control, 1 h thermoneutral immersion, dry dive, and 1 h thermoneutral immersion before a dive (preimmersion dive). Rats exposed to a dive were compressed to 700 kPa, maintained for 45 min breathing air, and decompressed linearly to the surface at a rate of 50 kPa/min. Postdive, the animals were anesthetized and the right ventricle insonated for bubble detection using ultrasound. Isolation of cardiomyocytes from the left ventricle was performed and studied using an inverted fluorescence microscope with video-based sarcomere spacing. Compared with a dry dive, preimmersion dive significantly increased bubble production and decreased the survival time (bubble grade 1 vs. 5, and survival time 60 vs. 17 min, respectively). Preimmersion dive lead to 18% decreased cardiomyocyte shortening, 20% slower diastolic relengthening, and 22% higher calcium amplitudes compared with controls. The protein levels of the sarco-endoplasmic reticulum calcium ATPase (SERCA2a), Na+/Ca2+ exchanger (NCX), and phospholamban phosphorylation in the left ventricular tissue were significantly reduced after both dry and preimmersion dive compared with control and immersed animals. The data suggest that immersion before a dive results in impaired cardiomyocyte and Ca2+ handling and may be a cellular explanation to reduced cardiac function observed in humans after a dive.

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Wada, F., S. Sagawa, K. Miki, K. Nagaya, S. Nakamitsu, K. Shiraki, and J. E. Greenleaf. "Mechanism of thirst attenuation during head-out water immersion in men." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 268, no. 3 (March 1, 1995): R583—R589. http://dx.doi.org/10.1152/ajpregu.1995.268.3.r583.

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The purpose was to determine whether extracellular volume or osmolality was the major contributing factor for reduction of thirst in air and head-out water immersion in hypohydrated subjects. Eight males (19-25 yr) were subjected to thermoneutral immersion and thermoneutral air under two hydration conditions without further drinking: euhydration in water (Eu-H2O) and euhydration in air, and hypohydration in water (Hypo-H2O) and hypohydration in air (3.7% wt loss after exercise in heat). The increased thirst sensation with Hypo-H2O decreased (P < 0.05) within 10 min of immersion and continued thereafter. Mean plasma osmolality (288 +/- 1 mosmol/kgH2O) and sodium (140 +/- 1 meq/l) remained elevated, and plasma volume increased by 4.2 +/- 1.0% (P < 0.05) throughout Hypo-H2O. A sustained increase (P < 0.05) in stroke volume accompanied the prompt and sustained decrease in plasma renin activity and sustained increase (P < 0.05) in plasma atrial natriuretic peptide during Eu-H2O and Hypo-H2O. Plasma vasopressin decreased from 5.3 +/- 0.7 to 2.9 +/- 0.5 pg/ml (P < 0.05) during Hypo-H2O but was unchanged in Eu-H2O. These findings suggest a sustained stimulation of the atrial baroreceptors and reduction of a dipsogenic stimulus without major alterations of extracellular osmolality in Hypo-H2O. Thus it appears that vascular volume-induced stimuli of cardiopulmonary baroreceptors play a more important role than extracellular osmolality in reducing thirst sensations during immersion in hypohydrated subjects.

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Mourot, Laurent, Malika Bouhaddi, Emmanuel Gandelin, Sylvie Cappelle, Gilles Dumoulin, Jean-Pierre Wolf, Jean Denis Rouillon, and Jacques Regnard. "Cardiovascular Autonomic Control During Short-Term Thermoneutral and Cool Head-Out Immersion." Aviation, Space, and Environmental Medicine 79, no. 1 (January 1, 2008): 14–20. http://dx.doi.org/10.3357/asem.2147.2008.

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Garzon, Mauricio, Olivier Dupuy, Laurent Bosquet, Anil Nigam, Alain Steve Comtois, Martin Juneau, and Mathieu Gayda. "Thermoneutral immersion exercise accelerates heart rate recovery: A potential novel training modality." European Journal of Sport Science 17, no. 3 (September 6, 2016): 310–16. http://dx.doi.org/10.1080/17461391.2016.1226391.

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Reed, Emma L., Morgan L. Worley, Nathan J. Klaes, Jacqueline C. Dirr, Dziana Vertsiakhouskaya, Manjoyt Sandhur, Zachary J. Schlader, and Blair D. Johnson. "The Effects Of Acute Thermoneutral And Hot Water Immersion On Cerebrovascular Reactivity." Medicine & Science in Sports & Exercise 52, no. 7S (July 2020): 973. http://dx.doi.org/10.1249/01.mss.0000686152.05282.42.

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Marmura, Hana, and Matthew Palmer. "Exercise Recovery with Cold and Thermoneutral Water Immersion and Performance in Athletes." Medicine & Science in Sports & Exercise 51, Supplement (June 2019): 648. http://dx.doi.org/10.1249/01.mss.0000562435.69398.54.

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Coulange, Mathieu, Florence Riera, Bruno Melin, Stephane Delliaux, Nathalie Kipson, Chantal Gimenez, Claude Robinet, and Yves Jammes. "Consequences of prolonged total thermoneutral immersion on muscle performance and EMG activity." Pflügers Archiv - European Journal of Physiology 455, no. 5 (October 2, 2007): 903–11. http://dx.doi.org/10.1007/s00424-007-0335-y.

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Burke, W. E., and I. B. Mekjavic. "Estimation of regional cutaneous cold sensitivity by analysis of the gasping response." Journal of Applied Physiology 71, no. 5 (November 1, 1991): 1933–40. http://dx.doi.org/10.1152/jappl.1991.71.5.1933.

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Regional cutaneous sensitivity to cooling was assessed in males by separately immersing four discrete skin regions in cold water (15 degrees C) during head-out immersion. The response measured was gasping at the onset of immersion; the gasping response appears to be the result of a nonthermoregulatory neurogenic drive from cutaneous cold receptors. Subjects of similar body proportions wore a neoprene “dry” suit modified to allow exposure to the water of either the arms, upper torso, lower torso, or legs, while keeping the unexposed skin regions thermoneutral. Each subject was immersed to the sternal notch in all four conditions of partial exposure plus one condition of whole body exposure. The five cold water conditions were matched by control immersions in lukewarm (34 degrees C) water, and trials were randomized. The magnitude of the gasping response was determined by mouth occlusion pressure (P0.1). For each subject, P0.1 values for the 1st min of immersion were integrated, and control trial values, although minimal, were subtracted from their cold water counterpart to account for any gasping due to the experimental design. Results were averaged and showed that the highest P0.1 values were elicited from whole body exposure, followed in descending order by exposures of the upper torso, legs, lower torso, and arms. Correction of the P0.1 response for differences in exposed surface area (A) and cooling stimulus (delta T) between regions gave a cold sensitivity index [CSI, P0.1/(A.delta T)] for each region and showed that the index for the upper torso was significantly higher than that for the arms or legs; no significant difference was observed between the indexes for the upper and lower torso.(ABSTRACT TRUNCATED AT 250 WORDS)

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Sackett, James R., Zachary J. Schlader, Christopher L. Chapman, and Blair D. Johnson. "Central Chemosensitivity is Augmented during Thermoneutral Head Out Water Immersion in Healthy Adults." Medicine & Science in Sports & Exercise 50, no. 5S (May 2018): 337. http://dx.doi.org/10.1249/01.mss.0000536190.70098.7a.

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Watenpaugh, Donald E., Bettina Pump, Peter Bie, and Peter Norsk. "Does gender influence human cardiovascular and renal responses to water immersion?" Journal of Applied Physiology 89, no. 2 (August 1, 2000): 621–28. http://dx.doi.org/10.1152/jappl.2000.89.2.621.

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We hypothesized that women and men exhibit similar cardiovascular and renal responses to thermoneutral water immersion (WI) to the neck. Ten women and nine men underwent two sessions in random order: 1) seated nonimmersed for 5.5 h (control) and 2) WI for 3 h, with subjects seated nonimmersed for 1.5 h pre- and 1 h postimmersion. We measured left atrial diameter, heart rate, arterial pressure, urine volume and osmolality, and urinary endothelin, urodilatin, sodium, and potassium excretion. No significant difference existed between groups in cardiovascular responses. The groups also exhibited mostly similar renal responses to immersion after adjustment for body mass. However, female urodilatin excretion per kilogram during immersion was over twofold that of men, and the female kaliuretic response to immersion was delayed and less pronounced relative to that in men. Men may excrete more potassium than women during immersion because men possess greater lean body mass (potassium per kilogram). Results obtained in men during WI may be cautiously extrapolated to women, yet urodilatin and potassium responses exhibit gender differences.

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Reed, Emma L., Morgan L. Worley, James Sackett, Adam C. Bloomfield, and Blair Johnson. "Muscle Sympathetic Nerve Activity during Thermoneutral Head‐Out Water Immersion with and without Hyperoxia." FASEB Journal 34, S1 (April 2020): 1. http://dx.doi.org/10.1096/fasebj.2020.34.s1.06426.

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Schega, Lutz, Gunter Claus, Michael Almeling, Andre Niklas, and Daniel J. Daly. "Cardiovascular Responses During Thermoneutral, Head-Out Water Immersion in Patients With Coronary Artery Disease." Journal of Cardiopulmonary Rehabilitation and Prevention 27, no. 2 (March 2007): 76–80. http://dx.doi.org/10.1097/01.hcr.0000265033.11930.99.

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Maxel, X., F. Girollet, L. Stubbe, E. Boudot, L. Darraillans, and J. L. Bodnar. "Aquatic Osteopathy Treatment Assessment by Infrared Thermography on Healthy Subjects After Thermoneutral Water Immersion." Journal of Chiropractic Medicine 18, no. 3 (September 2019): 188–97. http://dx.doi.org/10.1016/j.jcm.2019.07.007.

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Gordon, Christopher J., Alison L. Fogarty, John E. Greenleaf, Nigel A. S. Taylor, and Jodie M. Stocks. "Direct and indirect methods for determining plasma volume during thermoneutral and cold-water immersion." European Journal of Applied Physiology 89, no. 5 (June 2003): 471–74. http://dx.doi.org/10.1007/s00421-003-0823-5.

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Anderson, J. V., N. D. Millar, J. P. O'Hare, J. C. MacKenzie, R. J. M. Corrall, and S. R. Bloom. "Atrial natriuretic peptide: Physiological release associated with natriuresis during water immersion in man." Clinical Science 71, no. 3 (September 1, 1986): 319–22. http://dx.doi.org/10.1042/cs0710319.

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1. Thermoneutral water immersion produces a physiological increase of thoracic blood volume, raises central venous pressure and increases urinary sodium excretion by a hitherto ill-understood mechanism. We have investigated whether this enhanced sodium excretion could be mediated by the recently discovered natriuretic factor, atrial natriuretic peptide (ANP). 2. During water immersion there was a highly significant (P < 0.001) twofold increase of the mean plasma ANP concentration and a doubling of the mean urinary sodium excretion. Both were unchanged during the control experiments. 3. These results are consistent with the hypotheses (a) that ANP is released into plasma in response to central blood volume expansion and (b) that it functions as a natriuretic hormone in normal man under physiological conditions.

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Ayme, Karine, Olivier Gavarry, Pascal Rossi, Anne-Virginie Desruelle, Jacques Regnard, and Alain Boussuges. "Effect of head-out water immersion on vascular function in healthy subjects." Applied Physiology, Nutrition, and Metabolism 39, no. 4 (April 2014): 425–31. http://dx.doi.org/10.1139/apnm-2013-0153.

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Immersion in thermoneutral water increases cardiac output and peripheral blood flow and reduces systemic vascular resistance. This study examined the effects of head-out water immersion on vascular function. Twelve healthy middle-aged males were immersed during 60 min in the seated position, with water at the level of xiphoid. Local and central vascular tone regulating systems were studied during that time. Brachial artery diameter and blood flow were recorded using ultrasonography and Doppler. Endothelial function was assessed with flow-mediated dilation. Results were compared with the same investigations performed under reference conditions in ambient air. During water immersion, brachial artery diameter increased (3.7 ± 0.2 mm in ambient air vs. 4 ± 0.2 mm in water immersion; p < 0.05). Endothelium-mediated dilation was significantly lower in water immersion than in ambient air (10% vs. 15%; p = 0.01). Nevertheless, the difference disappeared when the percentage vasodilatation of the brachial artery was normalized to the shear stimulus. Smooth muscle-mediated dilation was similar in the 2 conditions. Spectral analysis of systolic blood pressure variability indicated a decrease in sympathetic vascular activity. Plasma levels of nitric oxide metabolites remained unchanged, whereas levels of natriuretic peptides were significantly elevated. An increase in brachial blood flow, a decrease in sympathetic activity, a warming of the skin, and an increase in natriuretic peptides might be involved in the increase in reference diameter observed during water immersion. Endothelial cell reactivity and smooth muscle function did not appear to be altered.

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Gabrielsen, A., L. B. Johansen, and P. Norsk. "Central cardiovascular pressures during graded water immersion in humans." Journal of Applied Physiology 75, no. 2 (August 1, 1993): 581–85. http://dx.doi.org/10.1152/jappl.1993.75.2.581.

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Thermoneutral (34.9 degrees C) water immersion (WI) was conducted with 12 upright seated normal males at four consecutive water levels (5–10 min each): knee (reference), xiphoid process, fourth intercostal space, and sternoclavicular notch. Thereafter, water was let out of the tank and the experiment was repeated from the neck to the knees at the same levels. Arterial pulse pressure (PP), central venous pressure (CVP), and transmural CVP (TCVP = CVP - esophageal pressure; n = 4) gradually increased with increasing water levels (P < 0.05). Heart rate (HR) decreased at WI to the xiphoid process (P < 0.05) and thereafter remained at this level, whereas mean arterial pressure remained unchanged. There was a closer linear correlation between HR and PP (r = -0.35, P < 0.01) than between HR and CVP (r = -0.13, P > 0.05). Furthermore, there was a significant positive linear correlation between CVP and TCVP (r = 0.83, P < 0.01). We conclude that WI in humans induces an increase in cardiac filling pressures with an increase in PP and a consequent decrease in HR. Furthermore, changes in CVP accurately reflect changes in cardiac distension (TCVP) during WI.

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Johansen, L. B., N. Foldager, C. Stadeager, M. S. Kristensen, P. Bie, J. Warberg, M. Kamegai, and P. Norsk. "Plasma volume, fluid shifts, and renal responses in humans during 12 h of head-out water immersion." Journal of Applied Physiology 73, no. 2 (August 1, 1992): 539–44. http://dx.doi.org/10.1152/jappl.1992.73.2.539.

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Changes in plasma volume (PV) throughout 12 h of thermoneutral (34.5 degrees C) water immersion (WI) were evaluated in eight subjects by an improved Evans blue (EB) technique and by measurements of hematocrit (Hct), hemoglobin (Hb), and plasma protein concentrations (Pprot). Appropriate time control studies (n = 6) showed no measurable change in PV. At 30 min of immersion, EB measurements demonstrated an increase in PV of 16 +/- 2% (457 +/- 70 ml). Calculations, however, based on concomitant changes in Hct, Hb, and Pprot showed an increase in PV of only 6.9 +/- 0.9 to 10.0 +/- 0.8% at 30 min of WI. PV values based on EB measurements subsequently declined throughout WI to (but not below) the preimmersion level. Concomitantly, changes in PV calculated from Pprot values remained increased, whereas estimations of changes in PV based on Hct and Hb values returned to prestudy levels after 4 h of immersion. It is concluded that PV initially increases by 16 +/- 2% during WI and does not decline below preimmersion and control levels during 12 h of immersion despite a loss of 0.9 +/- 0.2 liter of body fluid. Furthermore, changes in Hct, Hb, and Pprot do not provide accurate measures of the changes in PV during WI in humans.

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Weston, C. F. M., J. P. O'Hare, J. M. Evans, and R. J. M. Corrall. "Haemodynamic changes in man during immersion in water at different temperatures." Clinical Science 73, no. 6 (December 1, 1987): 613–16. http://dx.doi.org/10.1042/cs0730613.

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1. Stroke volume and cardiac output were measured using the Doppler ultrasound technique in 16 normal subjects immersed to the neck in water at 33°C, 35°C, 37°C and 39°C. A standard aortic diameter was assumed and results were expressed as percentage changes from pre-immersion resting values. 2. Cardiac output rose progressively at higher temperatures, increasing by 30% at 33°C and by 121% at 39°C. At thermoneutral temperatures (33°C and 35°C) this was achieved by an increase in stroke volume of 50% despite a significant decrease in heart rate. There was a further rise in stroke volume and pulse rate at higher temperatures and a mean tachycardia of 109 ± 4 beats/min was noted at 39°C. Calculated peripheral resistance reduced progressively with increasing temperature of immersion. 3. This non-invasive and simple technique may provide a non-exercise-related cardiovascular stress test to study cardiovascular responses in a variety of pathophysiological states.

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Worley, Morgan L., Emma L. Reed, Jacqueline C. Dirr, Zachary J. Schlader, and Blair D. Johnson. "Cerebral Autoregulation Is Not Different Between Hot And Thermoneutral Head-Out Water Immersion In Healthy Participants." Medicine & Science in Sports & Exercise 52, no. 7S (July 2020): 974. http://dx.doi.org/10.1249/01.mss.0000686156.78202.63.

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Nakamitsu, S., S. Sagawa, K. Miki, F. Wada, K. Nagaya, L. C. Keil, C. Drummer, et al. "Effect of water temperature on diuresis-natriuresis: AVP, ANP, and urodilatin during immersion in men." Journal of Applied Physiology 77, no. 4 (October 1, 1994): 1919–25. http://dx.doi.org/10.1152/jappl.1994.77.4.1919.

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Effects of water temperature on diuresis, natriuresis, and associated endocrine responses during head-out immersion were studied in eight men (23.4 +/- 0.3 yr) during four 5-h experimental conditions: air control at 28 degrees C and immersion at 34.5 degrees C [thermoneutral (Tnt)], 36 degrees C [above Tnt (aTnt)], and 32 degrees C [below Tnt (bTnt)]. Esophageal temperature decreased by approximately 0.4 degrees C in bTnt and increased by approximately 0.5 degrees C in aTnt. Cardiac output increased by approximately 80% in aTnt and approximately 40% in bTnt while thoracic impedance, an index of central blood pooling, decreased by 7.5 omega in bTnt (NS vs. Tnt) and 8.8 omega in aTnt (P < 0.05 vs. Tnt and bTnt). Total peripheral resistance decreased at all temperatures (50% in aTnt, 20% in bTnt). Urine flow and Na+ excretion increased by sixfold in bTnt and Tnt but by only threefold in aTnt. Creatinine clearance was unchanged while osmolal clearance (but not free water clearance) increased two-fold with all immersions. Plasma atrial natriuretic peptide (ANP), urinary urodilatin, and urinary guanosine 3′,5′-cyclic monophosphate increased while plasma renin activity, aldosterone, and arginine vasopressin (AVP) decreased similarly at all temperatures. bTnt did not potentiate diuresis by selective attenuation of AVP. The overall natriuretic response exhibited a higher correlation with urodilatin (r = 0.45, P < 0.001) than with ANP (r = 0.26, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

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Overmayer, Ryan, Francisco Tavares, and Matthew William Driller. "Acute Post-Exercise Recovery Strategies in Cycling: A Review." Journal of Science and Cycling 7, no. 3 (December 31, 2018): 11–44. http://dx.doi.org/10.28985/181231.jsc.04.

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Cycling events often include multiple races a day or racing over consecutive days. Congested competition schedules and increased training load have led to the implementation of recovery strategies; with the goal of alleviating post-exercise fatigue and enhancing subsequent performance. This review aims to review the efficacy of recovery strategies used following different cycling events. Compression garments have been shown to improve subsequent 30s – 30min mean cycling power and 5-min max cycling power, while cold water immersion may improve 5-15s sprint cycling power output, 1-15min time trial (TT) total work performed and mean power output in hot and humid conditions. Cold water immersion was also more beneficial than active recovery at improving total work performed. Contrast water therapy could increase 15s – 15min TT work performed and sprint mean and peak power output. Similarly, active recovery has been shown to improve power measures and time to completion. Conversely, hot water immersion appears to be detrimental to sprint power output and TT power output over consecutive days. Thermoneutral water immersion appears beneficial for improving average cycling speed and time to completion during a 20-km TT, where humidification therapy and sports massage are beneficial at improving sprint and middle duration time trial performance. A combination of recovery strategies appear more beneficial than stand-alone strategies and various combinations should be explored further.

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Pretorius, Thea, Dominique D. Gagnon, and Gordon G. Giesbrecht. "Core cooling and thermal responses during whole-head, facial, and dorsal immersion in 17 °C water." Applied Physiology, Nutrition, and Metabolism 35, no. 5 (October 2010): 627–34. http://dx.doi.org/10.1139/h10-057.

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This study isolated the effects of dorsal, facial, and whole-head immersion in 17 °C water on peripheral vasoconstriction and the rate of body core cooling. Seven male subjects were studied in thermoneutral air (∼28 °C). On 3 separate days, they lay prone or supine on a bed with their heads inserted through the side of an adjustable immersion tank. Following 10 min of baseline measurements, the water level was raised such that the water immersed the dorsum, face, or whole head, with the immersion period lasting 60 min. During the first 30 min, the core (esophageal) cooling rate increased from dorsum (0.29 ± 0.2 °C·h–1) to face (0.47 ± 0.1 °C·h–1) to whole head (0.69 ± 0.2 °C·h–1) (p < 0.001); cooling rates were similar during the final 30 min (mean, 0.16 ± 0.1 °C·h–1). During the first 30 min, fingertip blood flow (laser Doppler flux as percent of baseline) decreased faster in whole-head immersion (114 ± 52%·h–1) than in either facial (51 ± 47%·h–1) or dorsal (41 ± 55%·h–1) immersion (p < 0.03); rates of flow decrease were similar during minutes 30 to 60 (mean, 22.5 ± 19%·h–1). Total head heat loss over 60 min was significantly different between whole-head (120.5 ± 13 kJ), facial (86.8 ± 17 kJ), and dorsal (46.0 ± 11 kJ) immersion (p < 0.001). The rate of core cooling, relative to head heat loss, was similar in all conditions (mean, 0.0037 ± 0.001 °C·kJ–1). Although the whole head elicited a higher rate of vasoconstriction, the face did not elicit more vasoconstriction than the dorsum. Rather, the progressive increase in core cooling from dorsal to facial to whole-head immersion simply correlates with increased heat loss.

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Liner, M. H. "Tissue gas stores of the body and head-out immersion in humans." Journal of Applied Physiology 75, no. 3 (September 1, 1993): 1285–93. http://dx.doi.org/10.1152/jappl.1993.75.3.1285.

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Breath-by-breath gas exchange was studied in 10 subjects during and after transitions between dry conditions and head-out immersion in thermoneutral conditions. Cardiac index (CI) was estimated by means of impedance cardiography. Previous largely qualitative models of changes in tissue gas stores after blood volume shifts could be confirmed and extended to include a quantitative analysis of O2 and CO2 tissue stores. An increase in CI by 47.0% during immersion was associated with an increase in the tissue O2 stores by 122 ml/m2 and a decrease in the tissue CO2 stores by 148 ml/m2. The time constants for the recovery of O2 uptake (tau O2) and CO2 elimination after initial increases after the dry-to-immersion transition were 32.4 and 79.3 s, respectively. The decrease in CI on return to the dry conditions was associated with a drop in tissue O2 stores and a tau O2 of 144 s. The increase in tissue O2 stores during immersion as well as the difference in tau O2 between the two transitions were larger than could be explained by the change in CI only. This was attributed to changes in the distributions of peripheral blood flow and venous blood volume. Compared with the O2 stores, the decrease in CO2 stores was better predicted by the change in CI. The present results emphasize that the changes in pulmonary and tissue gas exchange imposed by head-out immersion transients mainly reflect movement of gas in and out of body stores.

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MacArthur, Robert A., and Alvin P. Dyck. "Aquatic thermoregulation of captive and free-ranging beavers (Castor canadensis)." Canadian Journal of Zoology 68, no. 11 (November 1, 1990): 2409–16. http://dx.doi.org/10.1139/z90-334.

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Abdominal cooling occurred in 91% of all aquatic excursions documented in free-ranging beavers during fall and winter. Kits aged 4–7 months cooled faster and spent less time foraging in 1–12 °C water than did animals > 1 year old. All beavers tested in the laboratory displayed abdominal cooling in 2–20 °C water, with maximal cooling rates recorded in a 5- to 7-week-old kit. Immersion in cold water induced strong peripheral cooling, though skin temperatures beneath the pelage remained within 4–5 °C of abdominal measurements. The resting metabolic rate of beavers > 1 year old was independent of water temperature between 19 and 31 °C, but increased proportionately at lower temperatures. Whole-body conductance of resting animals was on average 1.6–3.0 times higher in water than in air. Maximum testing metabolic rates in water varied from 1.8 to 2.4 times the mean resting thermoneutral rate in air. Our results suggest that beavers mitigate the thermogenic effort required in water by adopting a thermoregulatory strategy which combines avoidance of prolonged immersion with a tolerance to passive cooling.

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Krasney, J. A., M. Carroll, E. Krasney, J. Iwamoto, J. R. Claybaugh, and S. K. Hong. "Renal, hormonal, and fluid shift responses to ANP during head-out water immersion in awake dogs." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 261, no. 1 (July 1, 1991): R188—R197. http://dx.doi.org/10.1152/ajpregu.1991.261.1.r188.

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Renal responses to low doses of atrial natriuretic peptide (ANP) may be potentiated during water immersion-induced central hypervolemia. To test this hypothesis, ANP was infused in awake dogs in doses of 0, 5, and 25 ng.kg-1.min-1 either when the dogs were in air or during head-out water immersion (WI) under thermoneutral conditions (37 degrees C). In general, there were greater diuretic (V) and natriuretic responses (UNaV) at the same level of plasma ANP in WI, with the slopes (or sensitivities) of V and UNaV in relation to plasma ANP levels being significantly increased during WI. Plasma renin activity decreased only during WI and was significantly correlated with both V and UNaV only during WI. Plasma and urinary arginine vasopressin levels were unchanged during WI. Infusion of ANP prevented the usual decline of hematocrit that occurs during WI. These results support the view that the renal sensitivity to ANP is augmented during the plasma volume expansion of WI. In addition, ANP may attenuate the transcapillary fluid shift that occurs during WI.

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Norsk, P., F. Bonde-Petersen, and N. J. Christensen. "Catecholamines, circulation, and the kidney during water immersion in humans." Journal of Applied Physiology 69, no. 2 (August 1, 1990): 479–84. http://dx.doi.org/10.1152/jappl.1990.69.2.479.

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Because results in literature are discrepant with regard to the effects of water immersion (WI) on the release of norepinephrine (NE) in humans, the following study was performed. Simultaneous measurements of plasma NE, central cardiovascular variables, and renal sodium excretion were conducted in eight normal male subjects on 2 study days; 6 h of thermoneutral (35.0 degrees C) WI to the neck were preceded and followed by 1 h in the seated posture outside the water and 8 h of a seated control period. During the control period, the subjects wore a water-perfused garment (water temperature 34.6 degrees C) to obtain the same skin temperature as during WI. The subjects were fluid restricted overnight and kept in this condition throughout the study. Compared with the prestudy, post-study, and control periods, plasma NE decreased significantly by 61% during WI. Simultaneously, central venous pressure, cardiac output, stroke volume, systolic arterial pressure, and arterial pulse pressure increased, whereas heart rate decreased. Renal sodium excretion and urine flow rate increased. In conclusion, the release of NE is suppressed in humans during immersion. This decrease probably reflects a decrease in sympathetic nervous activity initiated by stimulation of low- and high-pressure baroreceptors. It is possible that the decrease in NE acts as one of several mechanisms of the natriuresis and diuresis of immersion in humans.

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Gabrielsen, Anders, Vibeke B. Sørensen, Bettina Pump, Søren Galatius, Regitze Videbæk, Peter Bie, Jørgen Warberg, et al. "Cardiovascular and neuroendocrine responses to water immersion in compensated heart failure." American Journal of Physiology-Heart and Circulatory Physiology 279, no. 4 (October 1, 2000): H1931—H1940. http://dx.doi.org/10.1152/ajpheart.2000.279.4.h1931.

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The hypothesis was tested that cardiovascular and neuroendocrine (norepinephrine, renin, and vasopressin) responses to central blood volume expansion are blunted in compensated heart failure (HF). Nine HF patients [New York Heart Association class II–III, ejection fraction = 0.28 ± 0.02 (SE)] and 10 age-matched controls (ejection fraction = 0.68 ± 0.03) underwent 30 min of thermoneutral (34.7 ± 0.02°C) water immersion (WI) to the xiphoid process. WI increased ( P < 0.05) central venous pressure by 3.7 ± 0.6 and 3.2 ± 0.4 mmHg and stroke volume index by 12.2 ± 2.1 and 7.2 ± 2.1 ml · beat−1 · m−2 in controls and HF patients, respectively. During WI, systemic vascular resistance decreased ( P < 0.05) similarly by 365 ± 66 and 582 ± 227 dyn · s · cm−5 in controls and HF patients, respectively. Forearm subcutaneous vascular resistance decreased by 19 ± 7% ( P < 0.05) in controls but did not change in HF patients. Heart rate decreased less during WI in HF patients, whereas release of norepinephrine, renin, and vasopressin was suppressed similarly in the two groups. We suggest that reflex control of forearm vascular beds and heart rate is blunted in compensated HF but that baroreflex-mediated systemic vasodilatation and neuroendocrine responses to central blood volume expansion are preserved.

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Takamata, A., G. W. Mack, N. S. Stachenfeld, and E. R. Nadel. "Body temperature modification of osmotically induced vasopressin secretion and thirst in humans." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 269, no. 4 (October 1, 1995): R874—R880. http://dx.doi.org/10.1152/ajpregu.1995.269.4.r874.

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We examined the effect of increased body core temperature (Tes) on the plasma arginine vasopressin concentration ([AVP]p) and thirst responses to increased plasma osmolality (Posm) induced by 3% NaCl infusion for 120 min in seven healthy humans. Tes was increased by immersion of the lower legs in 41 degrees C water in a 28 degrees C room (passive heating; HT). Immersion of the lower legs in 34.5 degrees C water on a separate day served as the control (thermoneutral; NT). The 120-min hypertonic saline infusion was initiated 30 min after the onset of leg immersion and was followed by a 30-min rehydration period. Tes in HT increased by 0.21 +/- 0.04 degree C before infusion and by 0.86 +/- 0.08 degree C at the end of infusion. The change in Tes in NT before and after the infusion was negligible. Posm was increased by 15.0 +/- 1.0 mosmol/kgH2O by infusion in both NT and HT. [AVP]p increased by 3.48 +/- 0.72 pg/ml in NT and by 7.59 +/- 1.02 pg/ml in HT. Thus the increase in [AVP]p at a given increase in Posm was markedly higher in HT than in NT. The plasma renin activity response to hypertonic saline infusion in both conditions was similar. Subjective thirst rating and cumulative water intake during rehydration were higher in HT than in NT.(ABSTRACT TRUNCATED AT 250 WORDS)

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Sackett, James R., Zachary J. Schlader, Morgan C. O'Leary, Christopher L. Chapman, and Blair D. Johnson. "Central chemosensitivity is augmented during 2 h of thermoneutral head-out water immersion in healthy men and women." Experimental Physiology 103, no. 5 (April 30, 2018): 714–27. http://dx.doi.org/10.1113/ep086870.

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Al Haddad, Hani, Paul B. Laursen, Didier Chollet, Frédéric Lemaitre, Saïd Ahmaidi, and Martin Buchheit. "Effect of cold or thermoneutral water immersion on post-exercise heart rate recovery and heart rate variability indices." Autonomic Neuroscience 156, no. 1-2 (August 2010): 111–16. http://dx.doi.org/10.1016/j.autneu.2010.03.017.

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Hurrie, Daryl M. G., and Gordon G. Giesbrecht. "Is active recovery during cold water immersion better than active or passive recovery in thermoneutral water for postrecovery high-intensity sprint interval performance?" Applied Physiology, Nutrition, and Metabolism 45, no. 3 (March 2020): 251–57. http://dx.doi.org/10.1139/apnm-2019-0189.

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High-intensity exercise is impaired by increased esophageal temperature (Tes) above 38 °C and/or decreased muscle temperature. We compared the effects of three 30-min recovery strategies following a first set of three 30-s Wingate tests (set 1), on a similar postrecovery set of Wingate tests (set 2). Recovery conditions were passive recovery in thermoneutral (34 °C) water (Passive-TN) and active recovery (underwater cycling; ∼33% maximum power) in thermoneutral (Active-TN) or cold (15 °C) water (Active-C). Tes rose for all conditions by the end of set 1 (∼1.0 °C). After recovery, Tes returned to baseline in both Active-C and Passive-TN but remained elevated in Active-TN (p < 0.05). At the end of set 2, Tes was lower in Active-C (37.2 °C) than both Passive-TN (38.1 °C) and Active-TN (38.8 °C) (p < 0.05). From set 1 to 2 mean power did not change with Passive-TN (+0.2%), increased with Active-TN (+2.4%; p < 0.05), and decreased with Active-C (–3.2%; p < 0.05). Heart rate was similar between conditions throughout, except at end-recovery; it was lower in Passive-TN (92 beats·min−1) than both exercise conditions (Active-TN, 126 beats·min−1; Active-C, 116 beats·min−1) (p < 0.05). Although Active-C significantly reduced Tes, the best postrecovery performance occurred with Active-TN. Novelty An initial set of 3 Wingates increased Tes to ∼38 °C. Thirty minutes of Active-C was well tolerated, and decreased Tes and blood lactate to baseline values, but decreased subsequent Wingate performance.

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Wester, T. E., A. D. Cherry, N. W. Pollock, J. J. Freiberger, M. J. Natoli, E. A. Schinazi, P. O. Doar, et al. "Effects of head and body cooling on hemodynamics during immersed prone exercise at 1 ATA." Journal of Applied Physiology 106, no. 2 (February 2009): 691–700. http://dx.doi.org/10.1152/japplphysiol.91237.2008.

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Immersion pulmonary edema (IPE) is a condition with sudden onset in divers and swimmers suspected to be due to pulmonary arterial or venous hypertension induced by exercise in cold water, although it does occur even with adequate thermal protection. We tested the hypothesis that cold head immersion could facilitate IPE via a reflex rise in pulmonary vascular pressure due solely to cooling of the head. Ten volunteers were instrumented with ECG and radial and pulmonary artery catheters and studied at 1 atm absolute (ATA) during dry and immersed rest and exercise in thermoneutral (29–31°C) and cold (18–20°C) water. A head tent varied the temperature of the water surrounding the head independently of the trunk and limbs. Heart rate, Fick cardiac output (CO), mean arterial pressure (MAP), mean pulmonary artery pressure (MPAP), pulmonary artery wedge pressure (PAWP), and central venous pressure (CVP) were measured. MPAP, PAWP, and CO were significantly higher in cold pool water ( P ≤ 0.004). Resting MPAP and PAWP values (means ± SD) were 20 ± 2.9/13 ± 3.9 (cold body/cold head), 21 ± 3.1/14 ± 5.2 (cold/warm), 14 ± 1.5/10 ± 2.2 (warm/warm), and 15 ± 1.6/10 ± 2.6 mmHg (warm/cold). Exercise values were higher; cold body immersion augmented the rise in MPAP during exercise. MAP increased during immersion, especially in cold water ( P < 0.0001). Except for a transient additive effect on MAP and MPAP during rapid head cooling, cold water on the head had no effect on vascular pressures. The results support a hemodynamic cause for IPE mediated in part by cooling of the trunk and extremities. This does not support the use of increased head insulation to prevent IPE.

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Glass, Stephen M., Christopher K. Rhea, Matthew W. Wittstein, Scott E. Ross, John P. Florian, and F. J. Haran. "Changes in Posture Following a Single Session of Long-Duration Water Immersion." Journal of Applied Biomechanics 34, no. 6 (December 1, 2018): 435–41. http://dx.doi.org/10.1123/jab.2017-0181.

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Transitioning between different sensory environments is known to affect sensorimotor function and postural control. Water immersion presents a novel environmental stimulus common to many professional and recreational pursuits, but is not well-studied with regard to its sensorimotor effects upon transitioning back to land. The authors investigated the effects of long-duration water immersion on terrestrial postural control outcomes in veteran divers. Eleven healthy men completed a 6-hour thermoneutral pool dive (4.57 m) breathing diver air. Center of pressure was observed before and 15 minutes after the dive under 4 conditions: (1) eyes open/stable surface (Open-Stable); (2) eyes open/foam surface (Open-Foam); (3) eyes closed/stable surface (Closed-Stable); and (4) eyes closed/foam surface (Closed-Foam). Postdive decreases in postural sway were observed in all testing conditions except for Open-Stable. The specific pattern of center of pressure changes in the postdive window is consistent with (1) a stiffening/overregulation of the ankle strategy during Open-Foam, Closed-Stable, and Closed-Foam or (2) acute upweighting of vestibular input along with downweighting of somatosensory, proprioceptive, and visual inputs. Thus, our findings suggest that postimmersion decreases in postural sway may have been driven by changes in weighting of sensory inputs and associated changes in balance strategy following adaptation to the aquatic environment.

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Miki, K., Y. Hayashida, S. Sagawa, and K. Shiraki. "Renal sympathetic nerve activity and natriuresis during water immersion in conscious dogs." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 256, no. 2 (February 1, 1989): R299—R305. http://dx.doi.org/10.1152/ajpregu.1989.256.2.r299.

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The role of renal sympathetic nerve activity (RSNA) in the natriuresis and diuresis induced by head-out water immersion (WI) was studied in eight conscious female dogs. The dog was instrumented chronically with a stainless steel electrode for the measurement of RSNA and two catheters for the measurements of systemic arterial (Pa) and central venous (Pv) pressures. The WI caused an immediate reduction of RSNA by 43 +/- 7% (P less than 0.05), and this low level was sustained throughout a 120-min WI under thermoneutral conditions (37 degrees C). Urine flow and sodium excretion increased by 211 +/- 54 (P less than 0.05) and 240 +/- 122% (P less than 0.05), respectively, but creatinine clearance did not change significantly during WI. A step increase in Pa (by 10 +/- 4 mmHg, P less than 0.05) and Pv (by 10.0 +/- 0.8 mmHg, P less than 0.05) was observed also during WI. In another series of studies, renal denervations were performed 2-4 wk before the experiment in six of the same dogs. Dogs with renal denervation showed no significant changes in urine flow and sodium excretion in response to WI, whereas Pa and Pv increased by 10 +/- 7 and 10.0 +/- 2.0 mmHg relative to the control level, respectively. It is concluded that the reduction of RSNA observed during WI plays a major role in the natriuresis in the dog.

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Fuchs, Cas J., Joey S. J. Smeets, Joan M. Senden, Antoine H. Zorenc, Joy P. B. Goessens, Wouter D. van Marken Lichtenbelt, Lex B. Verdijk, and Luc J. C. van Loon. "Hot-water immersion does not increase postprandial muscle protein synthesis rates during recovery from resistance-type exercise in healthy, young males." Journal of Applied Physiology 128, no. 4 (April 1, 2020): 1012–22. http://dx.doi.org/10.1152/japplphysiol.00836.2019.

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The purpose of this study was to assess the impact of postexercise hot-water immersion on postprandial myofibrillar protein synthesis rates during recovery from a single bout of resistance-type exercise in healthy, young men. Twelve healthy, adult men (age: 23 ± 1 y) performed a single bout of resistance-type exercise followed by 20 min of water immersion of both legs. One leg was immersed in hot water [46°C: hot-water immersion (HWI)], while the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g intrinsically L-[1-13C]-phenylalanine and L-[1-13C]-leucine labeled milk protein with 45 g of carbohydrates. In addition, primed continuous L-[ ring-2H5]-phenylalanine and L-[1-13C]-leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5-h recovery period. Muscle temperature immediately after water immersion was higher in the HWI compared with the CON leg (37.5 ± 0.1 vs. 35.2 ± 0.2°C; P < 0.001). Incorporation of dietary protein-derived L-[1-13C]-phenylalanine into myofibrillar protein did not differ between the HWI and CON leg during the 5-h recovery period (0.025 ± 0.003 vs. 0.024 ± 0.002 MPE; P = 0.953). Postexercise myofibrillar protein synthesis rates did not differ between the HWI and CON leg based upon L-[1-13C]-leucine (0.050 ± 0.005 vs. 0.049 ± 0.002%/h; P = 0.815) and L-[ ring-2H5]-phenylalanine (0.048 ± 0.002 vs. 0.047 ± 0.003%/h; P = 0.877), respectively. Hot-water immersion during recovery from resistance-type exercise does not increase the postprandial rise in myofibrillar protein synthesis rates. In addition, postexercise hot-water immersion does not increase the capacity of the muscle to incorporate dietary protein-derived amino acids in muscle tissue protein during subsequent recovery. NEW & NOTEWORTHY This is the first study to assess the effect of postexercise hot-water immersion on postprandial myofibrillar protein synthesis rates and the incorporation of dietary protein-derived amino acids into muscle protein. We observed that hot-water immersion during recovery from a single bout of resistance-type exercise does not further increase myofibrillar protein synthesis rates or augment the postprandial incorporation of dietary protein-derived amino acids in muscle throughout 5 h of postexercise recovery.

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Sackett, James R., Zachary J. Schlader, Suman Sarker, Christopher L. Chapman, and Blair D. Johnson. "Peripheral chemosensitivity is not blunted during 2 h of thermoneutral head out water immersion in healthy men and women." Physiological Reports 5, no. 20 (October 19, 2017): e13472. http://dx.doi.org/10.14814/phy2.13472.

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Crampton, David, Bernard Donne, Stuart A. Warmington, and Mikel Egaña. "Cycling time to failure is better maintained by cold than contrast or thermoneutral lower-body water immersion in normothermia." European Journal of Applied Physiology 113, no. 12 (October 6, 2013): 3059–67. http://dx.doi.org/10.1007/s00421-013-2737-1.

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Norsk, P., C. Drummer, L. B. Johansen, and R. Gerzer. "Effect of water immersion on renal natriuretic peptide (urodilatin) excretion in humans." Journal of Applied Physiology 74, no. 6 (June 1, 1993): 2881–85. http://dx.doi.org/10.1152/jappl.1993.74.6.2881.

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We examined 1) the effect of thermoneutral (34.5 +/- 0.5 degrees C) water immersion to the neck (WI) in humans on the temporal profile of renal urodilatin [atrial natriuretic peptide- (ANP) (95–,126)] excretion and 2) the relationship between urodilatin and urinary fluid (V) and sodium (UNaV) excretion. Eight normal subjects underwent 12 h of WI, and another group of eight were studied during seated control conditions. The subjects ingested 200 ml of tap water hourly. WI induced an increase in renal urodilatin and guanosine 3′,5′-cyclic monophosphate (cGMP) excretion, V, and UNaV. After peak values were attained between the 2nd and 5th h of WI, urodilatin and cGMP excretion, V, and UNaV returned toward preimmersion and control levels. At the 12th h of WI, urodilatin and cGMP excretion and V were indistinguishable from preimmersion values but were significantly elevated compared with the control values. UNaV was maintained elevated compared with both preimmersion and control values. During WI, positive and statistically significant linear correlations could be established between V and renal urodilatin excretion in six subjects and between UNaV and urodilatin excretion in four subjects. We conclude that WI induces an increase in the rate of renal urodilatin excretion, attaining a peak value at the 3rd h followed by an attenuation toward preimmersion and control levels. Furthermore, urodilatin might participate as one of several mechanisms of the natriuresis and diuresis of WI in humans.

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Hajduczok, G., K. Miki, J. R. Claybaugh, S. K. Hong, and J. A. Krasney. "Regional circulatory responses to head-out water immersion in conscious dogs." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 253, no. 2 (August 1, 1987): R254—R263. http://dx.doi.org/10.1152/ajpregu.1987.253.2.r254.

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We determined the regional blood flow responses to head-out water immersion (WI) in intact (INT) and cardiac-denervated (CD) conscious dogs. Immersing dogs in thermoneutral water (37 degrees C) in the quadruped position for 100 min resulted in significant increases in cardiac output (Qco) above control values by 38.7% in the INT dogs and 39.2% in the CD dogs (P less than 0.01). Arterial pressure increased by 32 and 34.7% in the INT and CD groups, respectively, during WI, with no significant changes occurring in the calculated total peripheral resistance. Regional blood flow responses were measured with 15-microns radiolabeled microspheres. Flows in the INT and CD groups increased significantly to the heart (40, 38%), skin (93, 96%), fat (79, 83%), diaphragm (44, 48%), and intercostal muscles (58, 55%), whereas there were no changes in renal cortical blood flows during WI. Total brain blood flows did not change significantly on immersion; however, blood flows in both INT and CD animals were increased to the cerebellum (19, 22%), but a significant decrease in pituitary flow (52%) was observed only in the CD group during WI. Gastrointestinal tissue flows increased only during early WI in both INT (45%) and CD (47%) animals. However, blood flows to the skeletal muscles increased only during late WI in the INT (53%) and CD (47%) groups. There were no significant differences between the INT and CD groups. Rectal temperatures and systemic O2 consumption (VO2) were unchanged during WI in both groups of animals. These observations indicate that WI leads to a sustained elevation of Qco accompanied by selective increases in regional tissue perfusion that may be accounted for in some tissues by an increase in metabolic demand or by local heating responses and produces a time-dependent redistribution of blood flow away from the gastrointestinal tissues toward skeletal muscle tissues, which may be due to a partial uncoupling of the normal Q/VO2 relationship. This may be caused by thermal or central neurohumoral mechanisms. These regional circulatory responses are not dependent on the presence of the cardiac nerves.

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Ahokas, E. K., H. Kyröläinen, A. A. Mero, S. Walker, H. G. Hanstock, and J. K. Ihalainen. "Water immersion methods do not alter muscle damage and inflammation biomarkers after high-intensity sprinting and jumping exercise." European Journal of Applied Physiology 120, no. 12 (September 2, 2020): 2625–34. http://dx.doi.org/10.1007/s00421-020-04481-8.

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Abstract Purpose The aim of this study was to compare the efficacy of three water immersion interventions performed after active recovery compared to active recovery only on the resolution of inflammation and markers of muscle damage post-exercise. Methods Nine physically active men (n = 9; age 20‒35 years) performed an intensive loading protocol, including maximal jumps and sprinting on four occasions. After each trial, one of three recovery interventions (10 min duration) was used in a random order: cold-water immersion (CWI, 10 °C), thermoneutral water immersion (TWI, 24 °C), contrast water therapy (CWT, alternately 10 °C and 38 °C). All of these methods were performed after an active recovery (10 min bicycle ergometer), and were compared to active recovery only (ACT). 5 min, 1, 24, 48, and 96 h after exercise bouts, immune response and recovery were assessed through leukocyte subsets, monocyte chemoattractant protein-1, myoglobin and high-sensitivity C-reactive protein concentrations. Results Significant changes in all blood markers occurred at post-loading (p < 0.05), but there were no significant differences observed in the recovery between methods. However, retrospective analysis revealed significant trial-order effects for myoglobin and neutrophils (p < 0.01). Only lymphocytes displayed satisfactory reliability in the exercise response, with intraclass correlation coefficient > 0.5. Conclusions The recovery methods did not affect the resolution of inflammatory and immune responses after high-intensity sprinting and jumping exercise. It is notable that the biomarker responses were variable within individuals. Thus, the lack of differences between recovery methods may have been influenced by the reliability of exercise-induced biomarker responses.

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Tajima, F., S. Sagawa, J. Iwamoto, K. Miki, J. R. Claybaugh, and K. Shiraki. "Renal and endocrine responses in the elderly during head-out water immersion." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 254, no. 6 (June 1, 1988): R977—R983. http://dx.doi.org/10.1152/ajpregu.1988.254.6.r977.

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After overnight food and fluid restriction, seven healthy old (62-74 yr) and eight young (21-28 yr) men were examined before, during, and after 3-h head-out immersion (HOI) in thermoneutral water (34.5 +/- 0.5 degrees C). On separate days, all subjects remained seated in air for 5 h to obtain the time control data. Although HOI induced a reversible increase in urine flow in all subjects, the response was faster and greater in magnitude in the elderly than in the young. Na excretion and osmolal clearance also followed a response pattern identical to that of urine flow; thus the HOI-induced diuresis was entirely osmotic. Endogenous creatinine clearance increased in the elderly at 2 h of HOI, suggesting an age-related modification in kidney hemodynamics. Although there was virtually the same cephalad blood shift (measured by impedance cardiography), mean arterial pressure significantly increased (P less than 0.05) during HOI in the elderly, which also indicated a different response of peripheral circulation to HOI in the elderly. Control level of plasma atrial natriuretic factor (ANF) was nearly twofold greater in the elderly compared with the young. The HOI induced a nearly fourfold increase in ANF in the elderly, whereas that for the young was threefold. Both plasma aldosterone and ADH responses to HOI were attenuated in the elderly compared with the young, which had no correlation with urine flow or Na excretion. It is concluded that the elderly release more ANF at a given cephalad volume expansion compared with the young, but the vasodilative reaction to ANF was attenuated in the elderly.

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Naumann, Johannes, Nina Bureau, Stefan Schmidt, Catharina Sadaghiani, and Roman Huber. "A single center three-arm parallel-group, randomized controlled study to evaluate antihypertensive effects of frequent immersion in thermoneutral water." International Journal of Cardiology 188 (June 2015): 73–75. http://dx.doi.org/10.1016/j.ijcard.2015.04.022.

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O'Brien, Catherine, and Scott J. Montain. "Hypohydration effect on finger skin temperature and blood flow during cold-water finger immersion." Journal of Applied Physiology 94, no. 2 (February 1, 2003): 598–603. http://dx.doi.org/10.1152/japplphysiol.00678.2002.

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This study was conducted to determine whether hypohydration (Hy) alters blood flow, skin temperature, or cold-induced vasodilation (CIVD) during peripheral cooling. Fourteen subjects sat in a thermoneutral environment (27°C) during 15-min warm-water (42°C) and 30-min cold-water (4°C) finger immersion (FI) while euhydrated (Eu) and, again, during Hy. Hy (−4% body weight) was induced before FI by exercise-heat exposure (38°C, 30% relative humidity) with no fluid replacement, whereas during Eu, fluid intake maintained body weight. Finger pad blood flow [as measured by laser-Doppler flux (LDF)] and nail bed (Tnb), pad (Tpad), and core (Tc) temperatures were measured. LDF decreased similarly during Eu and Hy (32 ± 10 and 33 ± 13% of peak during warm-water immersion). Mean Tnb and Tpad were similar between Eu (7.1 ± 1.0 and 11.5 ± 1.6°C) and Hy (7.4 ± 1.3 and 12.6 ± 2.1°C). CIVD parameters (e.g., nadir, onset time, apex) were similar between trials, except Tpad nadir was higher during Hy (10.4 ± 3.8°C) than during Eu (7.9 ± 1.6°C), which was attributed to higher Tc in six subjects during Hy (37.5 ± 0.2°C), compared with during Eu (37.1 ± 0.1°C). The results of this study provide no evidence that Hy alters finger blood flow, skin temperature, or CIVD during peripheral cooling.

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Tajima, F., S. Sagawa, J. Iwamoto, K. Miki, B. J. Freund, J. R. Claybaugh, and K. Shiraki. "Cardiovascular, renal, and endocrine responses in male quadriplegics during head-out water immersion." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 258, no. 6 (June 1, 1990): R1424—R1430. http://dx.doi.org/10.1152/ajpregu.1990.258.6.r1424.

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The present study was undertaken to determine the relative influence of the action of the central nervous system on the mechanism of water-immersion-induced diuresis by comparing physiological responses of quadriplegic (QP) and normal subjects. After overnight fasting seven male QP subjects with complete cervical cord transections (C5-C8) and six normal men were tested before, during, and after 3 h of head-out immersion (HOI) in thermoneutral water (34.5-35.0 degrees C). The reversible increase in urine flow and the total urine volume (309 +/- 53 ml in 3 h) in QP subjects were comparable with that of the normal subjects (318 +/- 96 ml in 3 h). While osmolal excretion was increased in QP subjects, its magnitude was less when compared with that of normal subjects. Instead, the increased urine flow in QP subjects was characterized by increased glomerular filtration rate (GFR) and free water clearance, in contrast to a predominantly osmotic diuresis with no changes in GFR in the normal subjects. The HOI elevated (P less than 0.05) systolic pressure only in QP subjects, whereas the increase in cardiac output was the same in both groups. While plasma renin activity and aldosterone responses to HOI in QP subjects were comparable with those of normal individuals, plasma atrial natriuretic factor (ANF) in QP subjects was twofold higher (P less than 0.05) during HOI, and the approximately threefold increase in ANF (P less than 0.05) in QP subjects due to HOI was the same as that of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

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Pesenti, Fernanda Bortolo, Rubens Alexandre da Silva, Daniel Correa Monteiro, Leticia Alves da Silva, and Christiane de Souza Guerino Macedo. "THE EFFECT OF COLD WATER IMMERSION ON PAIN, MUSCLE RECRUITMENT AND POSTURAL CONTROL IN ATHLETES." Revista Brasileira de Medicina do Esporte 26, no. 4 (August 2020): 323–27. http://dx.doi.org/10.1590/1517-869220202604214839.

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ABSTRACT Introduction Numerous recovery strategies have been used to minimize performance loss related to delayed onset muscle soreness in athletes, and are part of prevention programs and training of most high-level sports. Objective To analyze the effects of cold-water immersion on delayed-onset muscle soreness, muscle recruitment, and postural control in soccer players. Objective The maximum load of the quadriceps femoris muscle strength was determined. After three days, the pain scale was used to measure the subject’s pain intensity. The recruitment of the quadriceps muscle was determined at the moment of the kick, and was associated with postural control. Methods Randomized, blinded clinical trial study. Two repeated series of maximum load sets at 60% MVC, performed in a knee extension chair, were used to induce quadriceps fatigue in the athletes. Participants Twenty-eight soccer players were allocated to four intervention groups: cold water immersion (CWIG, n = 7), thermoneutral water immersion (TWIG, n = 7), active recovery (ARG, n = 7), and rest (RG, n = 7), with each intervention being carried out for ten minutes. Revaluations were carried out after 24, 48, and 72 hours of the fatigue protocol. Results Pain intensity in the CWIG returned to baseline after 72 hours, while the TWIG, ARG, and RG continued to feel greater pain. For the other outcomes, no differences were found between the groups. Conclusion With regard to muscle recruitment and postural control at the time of the kick, no significant differences were found for the time periods or intervention established. Level of evidence I; High-quality randomized clinical trial with or without statistically significant difference, but with narrow confidence intervals.

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Ferrigno, M., D. D. Hickey, M. H. Liner, and C. E. Lundgren. "Cardiac performance in humans during breath holding." Journal of Applied Physiology 60, no. 6 (June 1, 1986): 1871–77. http://dx.doi.org/10.1152/jappl.1986.60.6.1871.

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The effects on cardiac performance of high and low intrathoracic pressures induced by breath holding at large and small lung volumes have been investigated. Cardiac index and systolic time intervals were recorded from six resting subjects with impedance cardiography in both the nonimmersed and immersed condition. A thermoneutral environment (air 28 degrees C, water 35 degrees C) was used to eliminate the cold-induced circulatory component of the diving response. Cardiac performance was enhanced during immersion compared with nonimmersion, whereas it was depressed by breath holding at large lung volume. The depressed performance was apparent from the decrease in cardiac index (24.1% in the immersed and 20.9% in the nonimmersed condition) and from changes in systolic time intervals, e.g., shortening of left ventricular ejection time coupled with lengthening of preejection period. In the absence of the cold water component of the diving response, breath holding at the large lung volume used by breath-hold divers tends to reduce cardiac performance presumably by impeding venous return.

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Journal articles on the topic 'Thermoneutral immersion'

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