Altered thermoregulatory responses after 15 days of head-down tilt
Abstract
To determine whether extended exposure to a simulation of microgravity alters thermoregulatory reflex control of skin blood flow, six adult males (mean age 40 +/- 2 yr) were exposed to 15 days of 6 degrees head-down tilt (HDT). On an ambulatory control day before HDT exposure and on HDT day 15, the core temperature of each subject was increased by 0.5–1.0 degree C by whole body heating with a water-perfused suit. Mean skin temperature, oral temperature (Tor), mean arterial pressure, and forearm blood flow were measured throughout the protocol. Forearm vascular conductance (FVC) was calculated from the ratio of forearm blood flow to mean arterial pressure. After HDT exposure, the Tor threshold at which reflex thermally induced increases in FVC began was elevated (36.87 +/- 0.06 to 37.00 +/- 0.09 degrees C; P = 0.043), whereas the slope of the Tor-FVC relationship after this threshold was reduced (13.7 +/- 2.3 to 9.5 +/- 1.1 FVC units/degrees C; P = 0.038). Moreover, normothermic FVC and FVC at the highest common Tor between pre- and post-HDT trials were reduced after HDT (normothermic: 4.2 +/- 0.5 to 3.0 +/- 0.4 ml.100 ml-1.min-1.100 mmHg-1, P = 0.04; hyperthermic: 12.4 +/- 1.0 to 7.8 +/- 0.7 ml.100 ml-1.min-1.100 mmHg-1, P < 0.001). These data suggest that HDT exposure reduces thermoregulatory responses to heat stress. The mechanisms resulting in such an impaired thermoregulatory response are unknown but are likely related to the relative dehydration that accompanies this exposure.
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Previous research has noted increases in core body temperature during spaceflight and impaired thermoregulation during space analogs, but these studies were limited to short missions and did not investigate the effect of acute physical exercise on core body temperature.
“While previous research has noted increases in CBT during spaceflight15–17 and impaired thermoregulation during space analogs, i.e. head-down tilt bed rest18, these studies were limited to short missions and did not investigate the effect of acute physical exercise on CBT.”
From Increased core body temperature in astronauts during long-duration space missions (2017) · cites this paper as [18]
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CONVERTINO, V. A., BLOOMFIELD, S. A., & GREENLEAF, J. E. (1997) · Medicine &amp Science in Sports &amp Exercise · doi:10.1097/00005768-199702000-00004 · Cited by 309 · see citing works
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Shibasaki, M., Wilson, T. E., & Crandall, C. G. (2006) · Journal of Applied Physiology · doi:10.1152/japplphysiol.01124.2005 · Cited by 310 · see citing works
“(125) found that sweating responses to an exercise thermal stress, previously reported to be impaired after simulated and actual microgravity exposure (18, 29, 42, 67, 76), were preserved in subjects who exercise trained throughout bed rest.”
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Johnson, J. M., & Proppe, D. W. (1996) · Comprehensive physiology · doi:10.1002/cphy.cp040111 · Cited by 302 · see citing works
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McDonald, C. M. (2002) · American Journal of Physical Medicine & Rehabilitation · doi:10.1097/00002060-200211001-00012 · Cited by 224 · see citing works
Physiological, Pharmacokinetic, and Pharmacodynamic Changes in Space
Graebe, A., Schuck, E. L., Lensing, P., Putcha, L., & Derendorf, H. (2004) · The Journal of Clinical Pharmacology · doi:10.1177/0091270004267193 · Cited by 113 · see citing works
Increased core body temperature in astronauts during long-duration space missions
Stahn, A. C., Werner, A., Opatz, O., Maggioni, M. A., Steinach, M., von Ahlefeld, V. W., Moore, A., Crucian, B. E., Smith, S. M., Zwart, S. R., et al. (2017) · Scientific Reports · doi:10.1038/s41598-017-15560-w · Cited by 100 · see citing works
Blanc, S., Normand, S., Ritz, P., Pachiaudi, C., Vico, L., Gharib, C., & Gauquelin‐Koch, G. (1998) · The Journal of Clinical Endocrinology & Metabolism · doi:10.1210/jcem.83.12.5340 · Cited by 86 · see citing works
Physical training and the control of skin blood flow
Johnson, J. M. (1998) · Medicine & Science in Sports & Exercise · doi:10.1097/00005768-199803000-00007 · Cited by 86 · see citing works
Self-citationSimulated microgravity, psychic stress, and immune cells in men: observations during 120-day 6° HDT
Choukèr, A., Thiel, M., Баранов, В. М., Meshkov, D., Kotov, A. N., Peter, K., Messmer, K., & Christ, F. (2001) · Journal of Applied Physiology · doi:10.1152/jappl.2001.90.5.1736 · Cited by 59 · see citing works
“Besides adaptive changes of the cardiovascular system, permanent bed rest in the 6° HDT position is also a reliable and accepted experimental procedure to mimic the effects of microgravity on various other organ systems, including the neuromuscular apparatus (10, 15), thermoregulation (6), and the circadian rhythm (23…”
BackgroundEffect of increasing central venous pressure during passive heating on skin blood flow
Crandall, C. G., Levine, B. D., & Etzel, R. A. (1999) · Journal of Applied Physiology · doi:10.1152/jappl.1999.86.2.605 · Cited by 56 · see citing works
“These data provide a possible explanation for attenuated thermoregulatory responses in dehydrated subjects (9, 20) or in subjects exposed to simulated or actual microgravity (4, 8).”
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Boegli, Y., Gremion, G., Golay, S., Kübli, S., Liaudet, L., Leyvraz, P., Waeber, B., & Feihl, F. (2003) · Journal of Investigative Dermatology · doi:10.1046/j.1523-1747.2003.12518.x · Cited by 50 · see citing works
Crandall, C. G., Shibasaki, M., Wilson, T. E., Cui, J., & Levine, B. D. (2003) · Journal of Applied Physiology · doi:10.1152/japplphysiol.00790.2002 · Cited by 47 · see citing works
“Prior studies have identified that after actual and simulated spaceflight thermoregulatory responses are impaired as evidenced by elevated internal temperatures during exercise as well as reduced cutaneous vasodilator and sweating responses after actual and/or simulated microgravity exposure (7, 11, 13, 23).”
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“Salivary cortisol levels are closely correlated with blood cortisol levels and therefore reliably reflect HPA activity (13-16).”
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“, by long-term hypokinesia in head-down tilt (HDT) at 6° (7, 9, 17, 40) or by water immersion (8)].”
Role of skin blood flow and sweating rate in exercise thermoregulation after bed rest
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“(7) observed a significant increase in supine resting oral temperature after 15 days of bed rest in subjects wearing a waterperfused suit before the introduction of warm water.”
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Mueller, P. J., Clifford, P. S., Crandall, C. G., Smith, S. A., & Fadel, P. J. (2017) · Comprehensive physiology · doi:10.1002/cphy.c160040 · Cited by 48 · see citing works
Self-citationMueller, P. J., Foley, C. M., & Hasser, E. M. (2005) · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · doi:10.1152/ajpregu.00820.2004 · Cited by 30 · see citing works
“In addition, reduced dilation has been reported in the vasculatures of the forearm in patients on bed rest (10, 11, 29, 57) and in astronauts after long-term spaceflight (17).”
BackgroundExercise throughout 6° head-down tilt bed rest preserves thermoregulatory responses
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“Thus given these prior findings (5, 16, 20), coupled with the costs of repeating this study with nonexercising subjects, we chose to study the effects of aerobic exercise training during HDT bed rest only on subjects who exercised during bed rest exposure.”
BackgroundInfluentialSelf-citationHayashi, K., Honda, Y., Ogawa, T., Kondo, N., & Nishiyasu, T. (2009) · European Journal of Applied Physiology · doi:10.1007/s00421-009-1152-0 · Cited by 22 · see citing works
Attenuated thermoregulatory sweating and cutaneous vasodilation after 14-day bed rest in humans
Michikami, D., Kamiya, A., Fu, Q., Iwase, S., Mano, T., & Sunagawa, K. (2004) · Journal of Applied Physiology · doi:10.1152/japplphysiol.00025.2003 · Cited by 22 · see citing works
“A recent study has reported that HDBR attenuated thermoregulatory cutaneous vasodilation, whereas it increased the threshold temperature and decreasing sensitivity (7, 15).”
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“Higher HRs are attributed to the aforementioned narrow body heat dissipation gradient in hotter climates, with the resultant increase in BCT and skin temperature triggering augmented blood flow to the cutaneous circuit in order to permit greater heat dissipation [48].”
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BackgroundMueller, P., Clifford, P. S., Crandall, C., Smith, S. A., & Fadel, P. J. (2017) · Comprehensive Physiology · doi:10.1002/j.2040-4603.2018.tb00001.x · Cited by 36 · see citing works
Self-citationExercise training and 3-day head down bed rest deconditioning: exercise thermoregulation.
Smorawiński, J., Mlynarczyk, C. M., Ziemba, A. W., et al. (2005) · PubMed · Cited by 13 · see citing works
Navasiolava, N. M., de Germain, V., Levrard, T., et al. (2010) · Autonomic Neuroscience · doi:10.1016/j.autneu.2010.10.003 · Cited by 11 · see citing works
The influence of temporary semi-supine and supine postures on temperature regulation in humans
Aizawa, S., & Cabanac, M. (2002) · Journal of Thermal Biology · doi:10.1016/s0306-4565(01)00023-7 · Cited by 12 · see citing works
Sato, M., Kanikowska, D., Iwase, S., et al. (2009) · International Journal of Biometeorology · doi:10.1007/s00484-009-0230-7 · Cited by 8 · see citing works
GREENLEAF, J. E., Hutchinson, T., Shaffer-Bailey, M., et al. (1996) · European Journal of Applied Physiology · doi:10.1007/bf00599689 · Cited by 7 · see citing works
“Exercise thermoregulation under ambulatory conditions in humans with constant heat production appears to be controlled by heat dissipation responses; from sweating and evaporative heat loss (Greenleaf and Castle 1971), and also from heat transportation via change in blood flow from working muscles to and through the s…”
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Wyller, V. B. (2007) · Duo Research Archive (University of Oslo) · Cited by 6 · see citing works
Bhaskaran, S., Jagtap, S. S., & Vidyasagar, P. B. (2009) · Biophysical Reviews and Letters · doi:10.1142/s179304800900106x · Cited by 4 · see citing works
Cardiovascular Adjustments to Heat Stress
Johnson, J. M., & Proppe, D. W. (1994) · Comprehensive physiology · doi:10.1002/j.2040-4603.1994.tb01157.x · Cited by 3 · see citing works
Self-citationSteinach, M., & Gunga, H. (2019) · Springer eBooks · doi:10.1007/978-3-030-16996-1_9 · Cited by 3 · see citing works
Steinach, M., & Gunga, H. (2011) · Springer eBooks · doi:10.1007/978-3-642-22272-6_7 · Cited by 3 · see citing works
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Nimpal, M., Winter, P., Schnell, S., & zu Eulenburg, P. (2025) · Journal of Cerebral Blood Flow & Metabolism · doi:10.1177/0271678x251400470 · Cited by 1 · see citing works
“107, 108 There is compelling evidence that compromised CBF leads to an The absence of significant changes across all measured parameters during the Supine-Supine condition provides strong evidence that the neurovasculature is well adapted to uniform gravitational gradients.”
McKenna, Z. J., Sarma, S., Atkins, W. C., Gideon, E. A., McNary, J. L., & Crandall, C. G. (2025) · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · doi:10.1152/ajpregu.00276.2025 · Cited by 1 · see citing works
Self-citationPeripheral vascular responses to heat stress after hindlimb suspension
Looft‐Wilson, R. C., & GISOLFI, C. V. (2002) · Medicine & Science in Sports & Exercise · doi:10.1097/00005768-200207000-00011 · Cited by 1 · see citing works
The Development of a 2-Dimensional Human Thermal Model
Iyoho, A. E., Jang, T. S., & Nair, S. S. (2002) · SAE technical papers on CD-ROM/SAE technical paper series · doi:10.4271/2002-01-2540 · Cited by 1 · see citing works
Exercise temperature regulation following a 35‐day horizontal bedrest
Kounalakis, S. N., Keramidas, M. E., Eiken, O., & Mekjavić, I. B. (2021) · Experimental Physiology · doi:10.1113/ep089539 · Cited by 1 · see citing works
“Previous bedrest studies have also demonstrated a reduction in skin temperature and blood flow at resting thermoneutral conditions (Crandall et al., 1994, 2003; Keramidas et al., 2014; McDonnell et al., 2014), as well as an impairment in cutaneous vasodilatory responsiveness to thermal and/or…”
BackgroundResultHuman thermoregulation in microgravity environments: Insights from a computational model
Chithramol, M. K., & Shine, S. R. (2025) · Life Sciences in Space Research · doi:10.1016/j.lssr.2025.03.008 · Cited by 1 · see citing works
The Patient with Respiratory Failure—Preferred Practice Pattern 6F
Malone, D. J., & Adler, J. V. (2004) · Elsevier eBooks · doi:10.1016/b978-032301840-1.50019-0 · Cited by 1 · see citing works
Evetts, S. N. (2009) · Elsevier eBooks · doi:10.1016/b978-0-7506-8580-1.00003-8 · Cited by 1 · see citing works
Regulation and Heat Tolerance by Men in Heat Before and After Head-Down Tile
Xue-Jun, Y., Tiande, Y., Cheng, P., et al. (2005) · SAE technical papers on CD-ROM/SAE technical paper series · doi:10.4271/2005-01-2999
A importância da atividade física durante o período de imobilização.
Melo, A., & López, R. (2005) · Redalyc (Universidad Autónoma del Estado de México)
Pastushkova, L. K., Messmer, K., Peter, K., Thiel, M., Choukèr, A., Smith, L., Christ, F., Ларина, И. М., Ничипорук, И. А., Heppener, M., et al. (2015)
thermoregulation after bed rest Role of skin blood flow and sweating rate in exercise
Williams, W. J., Schneider, S. M., Crandall, C. G., et al. (2013)
Self-citationBrearley, M. B. (2006) · Charles Darwin University · doi:10.25913/5ea284be5d019
Kilroy, E. A. (2020) · DigitalCommons (California Polytechnic State University)
Digital Twin Definition for Detecting Abnormal Perspiration Patterns in High-Stress Professions
Vizitiu, C., Turcin, I., Dominey, K. A., Softic, S., Dinculescu, A. C., Bocăneț, V., Dugan, C., & Moraru, S.-A. (2024) · RoEduNet Conference: Networking in Education and Research (RoEduNet) · doi:10.1109/roedunet64292.2024.10722390
“Exposure to microgravity has been shown to reduce sweating as a thermoregulatory response, leading to the logical follow-up question of whether perspiration due to the psychological stimulus of high-stress situations also affects sweat pattens [19 - 21].”
BackgroundYeom, S., Kang, G.-R., Roh, S.-H., & Lee, J. (2025) · 한국생활환경학회지 · doi:10.21086/ksles.2025.10.32.5.604
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Platts, S. H., Stenger, M. B., Ribeiro, L. C., & Lee, S. M. C. (2010) · NASA Technical Reports Server (NASA)
- Authors
- Crandall, C. G., Johnson, J. M., Convertino, V. A., Raven, P. B., & Engelke, K. A.
- Affiliations
- Department of Physiology, Texas College of Osteopathic Medicine, Fort Worth 76107.
- Venue
- Journal of Applied Physiology
- Publisher
- American Physiological Society
- Published
- 1994-10-01
- Volume
- 77
- Issue
- 4
- Pages
- 1863-1867
- ISSN
- 0161-7567 (ISSN-L)
- 8750-7587
- 1522-1601
- OpenAlex
- W1905579438
- Cited by
- 54
- References
- 0
- Citations by year
- 2025: 4 · 2024: 1 · 2021: 2 · 2020: 2 · 2019: 1 · 2018: 1 · 2017: 2 · 2016: 1 · 2015: 1 · 2013: 1
- FWCI
- 1.13
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of Applied Physiology (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Institutes of Health (1f32hl008861-01)
- National Heart, Lung, and Blood Institute (HL-08861)
- Topics
- Health Sciences › Medicine › Physiology › Spaceflight effects on biology
- Health Sciences › Medicine › Physiology › Thermoregulation and physiological responses
- Health Sciences › Medicine › Surgery › Cardiovascular Syncope and Autonomic Disorders
- Keywords
- thermoregulation, head-down tilt, simulated microgravity, skin blood flow, forearm vascular conductance, heat stress, oral temperature, core body temperature, dehydration
- MeSH terms
- Adult, Blood Flow Velocity, Blood Pressure, Body Temperature, Body Temperature Regulation, Forearm, Hot Temperature, Humans, Male, Regional Blood Flow, Skin, Skin Physiological Phenomena, Skin Temperature, Sodium, Stress, Physiological, Vasoconstriction, Head-Down Tilt
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