1
|
Mastrandrea CJ, Hedge ET, Hughson RL. The Detrimental Effects of Bedrest: Premature Cardiovascular Aging and Dysfunction. Can J Cardiol 2024; 40:1468-1482. [PMID: 38759726 DOI: 10.1016/j.cjca.2024.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 05/08/2024] [Accepted: 05/09/2024] [Indexed: 05/19/2024] Open
Abstract
Bedrest as an experimental paradigm or as an in-patient stay for medical reasons has negative consequences for cardiovascular health. The effects of severe inactivity parallel many of the changes experienced with natural aging but over a much shorter duration. Cardiac function is reduced, arteries stiffen, neural reflex responses are impaired, and metabolic and oxidative stress responses impose burden on the heart and vascular systems. The effect of these changes is revealed in studies of integrative function. Aerobic fitness progressively deteriorates with bedrest and tolerance of upright posture is rapidly impaired. In this review we consider the similarities of aging and bedrest-induced cardiovascular deconditioning. We concur with many recent clinical recommendations that early and regular mobility with upright posture will reduce likelihood of hospital-associated disability related to bedrest.
Collapse
Affiliation(s)
- Carmelo J Mastrandrea
- Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada; Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Eric T Hedge
- Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada; Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Richard L Hughson
- Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada.
| |
Collapse
|
2
|
Mendes Zambetta R, Signini ÉDF, Ocamoto GN, Catai AM, Uliam NR, Santarnecchi E, Russo TL. Effects of weightlessness on the cardiovascular system: a systematic review and meta-analysis. Front Physiol 2024; 15:1438089. [PMID: 39129756 PMCID: PMC11310543 DOI: 10.3389/fphys.2024.1438089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2024] [Accepted: 07/02/2024] [Indexed: 08/13/2024] Open
Abstract
Background: The microgravity environment has a direct impact on the cardiovascular system due to the fluid shift and weightlessness that results in cardiac dysfunction, vascular remodeling, and altered Cardiovascular autonomic modulation (CAM), deconditioning and poor performance on space activities, ultimately endangering the health of astronauts. Objective: This study aimed to identify the acute and chronic effects of microgravity and Earth analogues on cardiovascular anatomy and function and CAM. Methods: CINAHL, Cochrane Library, Scopus, Science Direct, PubMed, and Web of Science databases were searched. Outcomes were grouped into cardiovascular anatomic, functional, and autonomic alterations, and vascular remodeling. Studies were categorized as Spaceflight (SF), Chronic Simulation (CS), or Acute Simulation (AS) based on the weightlessness conditions. Meta-analysis was performed for the most frequent outcomes. Weightlessness and control groups were compared. Results: 62 articles were included with a total of 963 participants involved. The meta-analysis showed that heart rate increased in SF [Mean difference (MD) = 3.44; p = 0.01] and in CS (MD = 4.98; p < 0.0001), whereas cardiac output and stroke volume decreased in CS (MD = -0.49; p = 0.03; and MD = -12.95; p < 0.0001, respectively), and systolic arterial pressure decreased in AS (MD = -5.20; p = 0.03). According to the qualitative synthesis, jugular vein cross-sectional area (CSA) and volume were greater in all conditions, and SF had increased carotid artery CSA. Heart rate variability and baroreflex sensitivity, in general, decreased in SF and CS, whereas both increased in AS. Conclusion: This review indicates that weightlessness impairs the health of astronauts during and after spaceflight, similarly to the effects of aging and immobility, potentially increasing the risk of cardiovascular diseases. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42020215515.
Collapse
Affiliation(s)
| | - Étore De Favari Signini
- Physical Therapy Department, Federal University of São Carlos, UFSCar, São Carlos, SP, Brazil
| | - Gabriela Nagai Ocamoto
- Physical Therapy Department, Federal University of São Carlos, UFSCar, São Carlos, SP, Brazil
- Brain4care Inc., São Carlos, SP, Brazil
| | - Aparecida Maria Catai
- Physical Therapy Department, Federal University of São Carlos, UFSCar, São Carlos, SP, Brazil
| | - Nicoly Ribeiro Uliam
- Physical Therapy Department, Federal University of São Carlos, UFSCar, São Carlos, SP, Brazil
| | | | - Thiago Luiz Russo
- Physical Therapy Department, Federal University of São Carlos, UFSCar, São Carlos, SP, Brazil
| |
Collapse
|
3
|
Robin A, Van Ombergen A, Laurens C, Bergouignan A, Vico L, Linossier MT, Pavy-Le Traon A, Kermorgant M, Chopard A, Py G, Green DA, Tipton M, Choukér A, Denise P, Normand H, Blanc S, Simon C, Rosnet E, Larcher F, Fernandez P, de Glisezinski I, Larrouy D, Harant-Farrugia I, Antunes I, Gauquelin-Koch G, Bareille MP, Billette De Villemeur R, Custaud MA, Navasiolava N. Comprehensive assessment of physiological responses in women during the ESA dry immersion VIVALDI microgravity simulation. Nat Commun 2023; 14:6311. [PMID: 37813884 PMCID: PMC10562467 DOI: 10.1038/s41467-023-41990-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 09/26/2023] [Indexed: 10/11/2023] Open
Abstract
Astronauts in microgravity experience multi-system deconditioning, impacting their inflight efficiency and inducing dysfunctions upon return to Earth gravity. To fill the sex gap of knowledge in the health impact of spaceflights, we simulate microgravity with a 5-day dry immersion in 18 healthy women (ClinicalTrials.gov Identifier: NCT05043974). Here we show that dry immersion rapidly induces a sedentarily-like metabolism shift mimicking the beginning of a metabolic syndrome with a drop in glucose tolerance, an increase in the atherogenic index of plasma, and an impaired lipid profile. Bone remodeling markers suggest a decreased bone formation coupled with an increased bone resorption. Fluid shifts and muscular unloading participate to a marked cardiovascular and sensorimotor deconditioning with decreased orthostatic tolerance, aerobic capacity, and postural balance. Collected datasets provide a comprehensive multi-systemic assessment of dry immersion effects in women and pave the way for future sex-based evaluations of countermeasures.
Collapse
Affiliation(s)
- Adrien Robin
- Univ Angers, CRC, CHU Angers, Inserm, CNRS, MITOVASC, Equipe CARME, SFR ICAT, F-49000, Angers, France.
| | | | - Claire Laurens
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Audrey Bergouignan
- Anschutz Health and Wellness Center, Division of Endocrinology, University of Colorado, Aurora, CO, USA
| | - Laurence Vico
- INSERM, University Jean Monnet, Mines Saint-Etienne, U 1059, Saint Etienne, France
| | | | - Anne Pavy-Le Traon
- Department of Neurology, CHU Toulouse and I2MC-INSERM 1297, Toulouse, France
| | - Marc Kermorgant
- Department of Neurology, CHU Toulouse and I2MC-INSERM 1297, Toulouse, France
| | - Angèle Chopard
- DMEM, Montpellier University, INRAE, Montpellier, France
| | - Guillaume Py
- DMEM, Montpellier University, INRAE, Montpellier, France
| | - David Andrew Green
- Centre of Human and Applied Physiological Sciences, King's College London, London, UK
| | - Michael Tipton
- Extreme Environments Laboratory, School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, PO1 2EF, UK
| | - Alexander Choukér
- Laboratory of Translational Research Stress and Immunity, Department of Anesthesiology, Hospital of the Ludwig-Maximilians-University (LUM), Munich, Germany
| | - Pierre Denise
- Université de Caen Normandie, Inserm, COMETE U1075, CYCERON, CHU de Caen, F-14000, Caen, France
| | - Hervé Normand
- Université de Caen Normandie, Inserm, COMETE U1075, CYCERON, CHU de Caen, F-14000, Caen, France
| | - Stéphane Blanc
- DEPE-IPHC - Département Ecologie, Physiologie et Ethologie, Strasbourg, France
| | - Chantal Simon
- CarMeN Laboratory, INSERM 1060, INRA 1397, University Claude Bernard Lyon1, Human Nutrition Research Center Rhône-Alpes, Oullins, France
| | - Elisabeth Rosnet
- Faculty of Sport Sciences, Université de Reims Champagne-Ardenne, Reims, France
| | | | - Peter Fernandez
- INSERM, University Jean Monnet, Mines Saint-Etienne, U 1059, Saint Etienne, France
| | - Isabelle de Glisezinski
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Dominique Larrouy
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Isabelle Harant-Farrugia
- Institute of Metabolic and Cardiovascular Diseases, INSERM, Paul Sabatier University, UMR1297, Toulouse, France
| | - Inês Antunes
- Telespazio Belgium S.R.L. for the European Space Agency, Noordwijk, The Netherlands
| | | | | | | | - Marc-Antoine Custaud
- Univ Angers, CRC, CHU Angers, Inserm, CNRS, MITOVASC, Equipe CARME, SFR ICAT, F-49000, Angers, France.
| | - Nastassia Navasiolava
- Univ Angers, CRC, CHU Angers, Inserm, CNRS, MITOVASC, Equipe CARME, SFR ICAT, F-49000, Angers, France.
| |
Collapse
|
4
|
Rabineau J, Issertine M, Hoffmann F, Gerlach D, Caiani EG, Haut B, van de Borne P, Tank J, Migeotte PF. Cardiovascular deconditioning and impact of artificial gravity during 60-day head-down bed rest—Insights from 4D flow cardiac MRI. Front Physiol 2022; 13:944587. [PMID: 36277205 PMCID: PMC9586290 DOI: 10.3389/fphys.2022.944587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2022] [Accepted: 09/13/2022] [Indexed: 12/03/2022] Open
Abstract
Microgravity has deleterious effects on the cardiovascular system. We evaluated some parameters of blood flow and vascular stiffness during 60 days of simulated microgravity in head-down tilt (HDT) bed rest. We also tested the hypothesis that daily exposure to 30 min of artificial gravity (1 g) would mitigate these adaptations. 24 healthy subjects (8 women) were evenly distributed in three groups: continuous artificial gravity, intermittent artificial gravity, or control. 4D flow cardiac MRI was acquired in horizontal position before (−9 days), during (5, 21, and 56 days), and after (+4 days) the HDT period. The false discovery rate was set at 0.05. The results are presented as median (first quartile; third quartile). No group or group × time differences were observed so the groups were combined. At the end of the HDT phase, we reported a decrease in the stroke volume allocated to the lower body (−30% [−35%; −22%]) and the upper body (−20% [−30%; +11%]), but in different proportions, reflected by an increased share of blood flow towards the upper body. The aortic pulse wave velocity increased (+16% [+9%; +25%]), and so did other markers of arterial stiffness (CAVI; CAVI0). In males, the time-averaged wall shear stress decreased (−13% [−17%; −5%]) and the relative residence time increased (+14% [+5%; +21%]), while these changes were not observed among females. Most of these parameters tended to or returned to baseline after 4 days of recovery. The effects of the artificial gravity countermeasure were not visible. We recommend increasing the load factor, the time of exposure, or combining it with physical exercise. The changes in blood flow confirmed the different adaptations occurring in the upper and lower body, with a larger share of blood volume dedicated to the upper body during (simulated) microgravity. The aorta appeared stiffer during the HDT phase, however all the changes remained subclinical and probably the sole consequence of reversible functional changes caused by reduced blood flow. Interestingly, some wall shear stress markers were more stable in females than in males. No permanent cardiovascular adaptations following 60 days of HDT bed rest were observed.
Collapse
Affiliation(s)
- Jeremy Rabineau
- LPHYS, Département de Cardiologie, Université Libre de Bruxelles, Brussels, Belgium
- TIPs, École Polytechnique de Bruxelles, Université Libre de Bruxelles, Brussels, Belgium
- *Correspondence: Jeremy Rabineau,
| | - Margot Issertine
- LPHYS, Département de Cardiologie, Université Libre de Bruxelles, Brussels, Belgium
| | - Fabian Hoffmann
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Darius Gerlach
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Enrico G. Caiani
- Electronic, Information and Biomedical Engineering Department, Politecnico di Milano, Milan, Italy
| | - Benoit Haut
- TIPs, École Polytechnique de Bruxelles, Université Libre de Bruxelles, Brussels, Belgium
| | | | - Jens Tank
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | | |
Collapse
|
5
|
Frett T, Lecheler L, Speer M, Marcos D, Pesta D, Tegtbur U, Schmitz MT, Jordan J, Green DA. Comparison of trunk muscle exercises in supine position during short arm centrifugation with 1 g at centre of mass and upright in 1 g. Front Physiol 2022; 13:955312. [PMID: 36060705 PMCID: PMC9428406 DOI: 10.3389/fphys.2022.955312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/26/2022] [Indexed: 12/02/2022] Open
Abstract
Spaceflight is associated with reduced antigravitational muscle activity, which results in trunk muscle atrophy and may contribute to post-flight postural and spinal instability. Exercise in artificial gravity (AG) performed via short-arm human centrifugation (SAHC) is a promising multi-organ countermeasure, especially to mitigate microgravity-induced postural muscle atrophy. Here, we compared trunk muscular activity (mm. rectus abdominis, ext. obliques and multifidi), cardiovascular response and tolerability of trunk muscle exercises performed during centrifugation with 1 g at individual center of mass on a SAHC against standard upright exercising. We recorded heart rate, blood pressure, surface trunk muscle activity, motion sickness and rating of perceived exertion (BORG) of 12 participants (8 male/4 female, 34 ± 7 years, 178.4 ± 8.2 cm, 72.1 ± 9.6 kg). Heart rate was significantly increased (p < 0.001) during exercises without differences in conditions. Systolic blood pressure was higher (p < 0.001) during centrifugation with a delayed rise during exercises in upright condition. Diastolic blood pressure was lower in upright (p = 0.018) compared to counter-clockwise but not to clockwise centrifugation. Target muscle activation were comparable between conditions, although activity of multifidi was lower (clockwise: p = 0.003, counter-clockwise: p < 0.001) and rectus abdominis were higher (clockwise: p = 0.0023, counter-clockwise: < 0.001) during centrifugation in one exercise type. No sessions were terminated, BORG scoring reflected a relevant training intensity and no significant increase in motion sickness was reported during centrifugation. Thus, exercising trunk muscles during centrifugation generates comparable targeted muscular and heart rate response and appears to be well tolerated. Differences in blood pressure were relatively minor and not indicative of haemodynamic challenge. SAHC-based muscle training is a candidate to reduce microgravity-induced inter-vertebral disc pathology and trunk muscle atrophy. However, further optimization is required prior to performance of a training study for individuals with trunk muscle atrophy/dysfunction.
Collapse
Affiliation(s)
- Timo Frett
- German Aerospace Center, Institute of Aerospace Medicine, Cologne, Germany
- *Correspondence: Timo Frett,
| | - Leopold Lecheler
- German Aerospace Center, Institute of Aerospace Medicine, Cologne, Germany
| | | | | | - Dominik Pesta
- German Aerospace Center, Institute of Aerospace Medicine, Cologne, Germany
- Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | - Uwe Tegtbur
- Hannover Medical School, Institutes of Sports Medicine, Hannover, Germany
| | - Marie-Therese Schmitz
- German Aerospace Center, Institute of Aerospace Medicine, Cologne, Germany
- Informatics and Epidemiology, Institute of Medical Biometry, Medical Faculty, University of Bonn, Bonn, Germany
| | - Jens Jordan
- German Aerospace Center, Institute of Aerospace Medicine, Cologne, Germany
- Chair of Aerospace Medicine, University of Cologne, Cologne, Germany
| | - David Andrew Green
- European Space Agency, Cologne, Germany
- King’s College London, London, United Kingdom
- Space Medicine Team, European Astronaut Centre, European Space Agency, Cologne, Germany
- KBRwyle GmbH, Cologne, Germany
| |
Collapse
|
6
|
Hedge ET, Patterson CA, Mastrandrea CJ, Sonjak V, Hajj-Boutros G, Faust A, Morais JA, Hughson RL. Implementation of exercise countermeasures during spaceflight and microgravity analogue studies: Developing countermeasure protocols for bedrest in older adults (BROA). Front Physiol 2022; 13:928313. [PMID: 36017336 PMCID: PMC9395735 DOI: 10.3389/fphys.2022.928313] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/27/2022] [Indexed: 12/18/2022] Open
Abstract
Significant progress has been made in the development of countermeasures to attenuate the negative consequences of prolonged exposure to microgravity on astronauts’ bodies. Deconditioning of several organ systems during flight includes losses to cardiorespiratory fitness, muscle mass, bone density and strength. Similar deconditioning also occurs during prolonged bedrest; any protracted time immobile or inactive, especially for unwell older adults (e.g., confined to hospital beds), can lead to similar detrimental health consequences. Due to limitations in physiological research in space, the six-degree head-down tilt bedrest protocol was developed as ground-based analogue to spaceflight. A variety of exercise countermeasures have been tested as interventions to limit detrimental changes and physiological deconditioning of the musculoskeletal and cardiovascular systems. The Canadian Institutes of Health Research and the Canadian Space Agency recently provided funding for research focused on Understanding the Health Impact of Inactivity to study the efficacy of exercise countermeasures in a 14-day randomized clinical trial of six-degree head-down tilt bedrest study in older adults aged 55–65 years old (BROA). Here we will describe the development of a multi-modality countermeasure protocol for the BROA campaign that includes upper- and lower-body resistance exercise and head-down tilt cycle ergometry (high-intensity interval and continuous aerobic exercise training). We provide reasoning for the choice of these modalities following review of the latest available information on exercise as a countermeasure for inactivity and spaceflight-related deconditioning. In summary, this paper sets out to review up-to-date exercise countermeasure research from spaceflight and head-down bedrest studies, whilst providing support for the proposed research countermeasure protocols developed for the bedrest study in older adults.
Collapse
Affiliation(s)
- Eric T. Hedge
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON, Canada
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | | | | | - Vita Sonjak
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - Guy Hajj-Boutros
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - Andréa Faust
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - José A. Morais
- Research Institute of McGill University Health Centre, McGill University, Montréal, QC, Canada
- Division of Geriatric Medicine, McGill University Health Centre, McGill University, Montréal, QC, Canada
| | - Richard L. Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON, Canada
- *Correspondence: Richard L. Hughson,
| |
Collapse
|
7
|
Tomilovskaya E, Amirova L, Nosikova I, Rukavishnikov I, Chernogorov R, Lebedeva S, Saveko A, Ermakov I, Ponomarev I, Zelenskaya I, Shigueva T, Shishkin N, Kitov V, Riabova A, Brykov V, Abu Sheli N, Vassilieva G, Orlov O. The First Female Dry Immersion (NAIAD-2020): Design and Specifics of a 3-Day Study. Front Physiol 2021; 12:661959. [PMID: 34194336 PMCID: PMC8236811 DOI: 10.3389/fphys.2021.661959] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 05/19/2021] [Indexed: 11/17/2022] Open
Abstract
This article describes procedures and some results of the first study of females undergoing 3-day Dry Immersion. The experiment “NAIAD-2020” was carried out at the Institute of Biomedical Problems (Moscow, Russia) with the participation of six healthy women volunteers (age 30.17 ± 5.5 years, height 1.66 ± 0.1 m, weight 62.05 ± 8.4 kg, BMI 22.39 ± 2.2 kg/m2) with a natural menstrual cycle. During the study, a standard protocol was used, the same as for men, with a minimum period of time spent outside the immersion bath. Before, during and after Immersion, 22 experiments were carried out aimed at studying the neurophysiological, functional, metabolic and psychophysiological functions of the body, the results of which will be presented in future publications. The total time outside the bath for women did not exceed that for men. Systolic and diastolic pressure did not significantly change during the immersion. In the first 24 h after the end of the immersion, heart rate was significantly higher than the background values [F(4,20) = 14.67; P < 0.0001]. Changes in body temperature and water balance were consistent with the patterns found in men. No significant changes in height and weight were found during immersion. All women reported general discomfort and pain in the abdomen and back. The results of this study did not find significant risks to women’s health and showed the feasibility of using this model of the effects of space flight in women of reproductive age.
Collapse
Affiliation(s)
- Elena Tomilovskaya
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Liubov Amirova
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Inna Nosikova
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Ilya Rukavishnikov
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Roman Chernogorov
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Svetlana Lebedeva
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Alina Saveko
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Ivan Ermakov
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Ivan Ponomarev
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Inna Zelenskaya
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Tatiana Shigueva
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Nikita Shishkin
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Vladimir Kitov
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Alexandra Riabova
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Vitaly Brykov
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Nelly Abu Sheli
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Galina Vassilieva
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| | - Oleg Orlov
- Russian Federation State Scientific Center - Institute of Biomedical Problems of the Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
8
|
Möstl S, Orter S, Hoffmann F, Bachler M, Hametner B, Wassertheurer S, Rabineau J, Mulder E, Johannes B, Jordan J, Tank J. Limited Effect of 60-Days Strict Head Down Tilt Bed Rest on Vascular Aging. Front Physiol 2021; 12:685473. [PMID: 34122149 PMCID: PMC8194311 DOI: 10.3389/fphys.2021.685473] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/04/2021] [Indexed: 11/13/2022] Open
Abstract
Background Cardiovascular risk may be increased in astronauts after long term space flights based on biomarkers indicating premature vascular aging. We tested the hypothesis that 60 days of strict 6° head down tilt bed rest (HDTBR), an established space analog, promotes vascular stiffening and that artificial gravity training ameliorates the response. Methods We studied 24 healthy participants (8 women, 24–55 years, BMI = 24.3 ± 2.1 kg/m2) before and at the end of 60 days HDTBR. 16 subjects were assigned to daily artificial gravity. We applied echocardiography to measure stroke volume and isovolumetric contraction time (ICT), calculated aortic compliance (stroke volume/aortic pulse pressure), and assessed aortic distensibility by MRI. Furthermore, we measured brachial-femoral pulse wave velocity (bfPWV) and pulse wave arrival times (PAT) in different vascular beds by blood pressure cuffs and photoplethysmography. We corrected PAT for ICT (cPAT). Results In the pooled sample, diastolic blood pressure (+8 ± 7 mmHg, p < 0.001), heart rate (+7 ± 9 bpm, p = 0.002) and ICT (+8 ± 13 ms, p = 0.036) increased during HDTBR. Stroke volume decreased by 14 ± 15 ml (p = 0.001). bfPWV, aortic compliance, aortic distensibility and all cPAT remained unchanged. Aortic area tended to increase (p = 0.05). None of the parameters showed significant interaction between HDTBR and artificial gravity training. Conclusion 60 days HDTBR, while producing cardiovascular deconditioning and cephalad fluid shifts akin to weightlessness, did not worsen vascular stiffness. Artificial gravity training did not modulate the response.
Collapse
Affiliation(s)
- Stefan Möstl
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Stefan Orter
- Center for Health and Bioresources, AIT Austrian Institute of Technology, Vienna, Austria
| | - Fabian Hoffmann
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany.,Department of Cardiology, University Hospital Cologne, Cologne, Germany
| | - Martin Bachler
- Center for Health and Bioresources, AIT Austrian Institute of Technology, Vienna, Austria
| | - Bernhard Hametner
- Center for Health and Bioresources, AIT Austrian Institute of Technology, Vienna, Austria
| | | | - Jérémy Rabineau
- Laboratory of Physics and Physiology, University of Brussels, Brussels, Belgium
| | - Edwin Mulder
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Bernd Johannes
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| | - Jens Jordan
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany.,Chair of Aerospace Medicine, University Hospital Cologne, Cologne, Germany
| | - Jens Tank
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Cologne, Germany
| |
Collapse
|
9
|
Ogoh S, Sato K, de Abreu S, Denise P, Normand H. Effect of jump exercise training on long-term head-down bed rest-induced cerebral blood flow responses in arteries and veins. Exp Physiol 2021; 106:1549-1558. [PMID: 33866619 DOI: 10.1113/ep089102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 03/29/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the effect of an exercise countermeasure on microgravity-induced change in cerebral blood flow? What is the main finding and its importance? Jump exercise training as a countermeasure did not modify the heterogeneous cerebral blood flow response to head-down bed rest, suggesting that this method is effective in preventing cardiovascular system deconditioning but is not good for cerebral haemodynamics. ABSTRACT This study aimed to examine the effect of an exercise countermeasure on cerebral blood flow (CBF) response to long-term -6° head-down bed rest (HDBR) in all cerebral arteries and veins. Twenty male volunteers were exposed to HDBR for 60 days with (training group, n = 10) or without (control group, n = 10) jump exercise training as a countermeasure to spaceflight. The blood flow in the neck conduit arteries (internal carotid and vertebral artery; ICA and VA) and veins (internal jugular and vertebral veins; IJV and VV) was measured, using ultrasonography before (baseline) HDBR, on the 30th and 57th day of HDBR. Long-term HDBR causes a heterogeneous CBF response between the anterior and the posterior brain or between arteries and veins. Long-term HDBR decreased anterior cerebral arterial and venous blood flow, while posterior cerebral arterial and venous blood flows were well maintained. However, exercise jump training did not change each arterial and venous CBF responses to HDBR (control vs. training; ICA, P = 0.643; VA, P = 0.542; external carotid artery, P = 0.644; IJV, P = 0.980; VV, P = 0.999). These findings suggest that jump exercise training did not modify the heterogeneous CBF response to long-term HDBR.
Collapse
Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | | | - Steven de Abreu
- Unicaen, Inserm Comete, GIP Cyceron, Normandie University, Caen, France
| | - Pierre Denise
- Unicaen, Inserm Comete, GIP Cyceron, Normandie University, Caen, France
| | - Hervé Normand
- Unicaen, Inserm Comete, GIP Cyceron, Normandie University, Caen, France
| |
Collapse
|
10
|
Guinet P, MacNamara JP, Berry M, Larcher F, Bareille MP, Custaud MA, Pavy-Le Traon A, Levine BD, Navasiolava N. MNX (Medium Duration Nutrition and Resistance-Vibration Exercise) Bed-Rest: Effect of Resistance Vibration Exercise Alone or Combined With Whey Protein Supplementation on Cardiovascular System in 21-Day Head-Down Bed Rest. Front Physiol 2020; 11:812. [PMID: 32765296 PMCID: PMC7378749 DOI: 10.3389/fphys.2020.00812] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/18/2020] [Indexed: 12/20/2022] Open
Abstract
Current inflight countermeasures do not completely prevent bone and cardiovascular changes induced by microgravity. High load Resistance Exercise combined with whole body Vibration (RVE) demonstrated benefits on bone and cardiovascular system during previous Head-Down Bed Rest (HDBR) studies. We examined the effectiveness of RVE alone or combined with a nutritional supplementation of Whey protein (NeX) on cardiovascular deconditioning. Eight male subjects (age 34 ± 8 years) in a crossover design completed three 21-day HDBR campaigns (Control-CON, RVE, and NeX). Pre and post HDBR Orthostatic Tolerance (OT) was evaluated by a 15-min head-up tilt test followed by increasing levels of Lower Body Negative Pressure (LBNP). Heart rate (HR), blood pressure (BP), and Sympathetic Index (ΣI) through spectral analysis were measured during OT test. Plasma Volume (PV), and Maximal Oxygen Uptake (VO2max) were measured before and after each campaign. Left ventricular mass, left ventricular end diastolic (LVEDV), end systolic (LVESV), stroke (SV) volumes, and circumferential deformation at rest and during an orthostatic stress simulated by a 30 mmHg LBNP were measured by cardiac MRI. RVE failed to prevent any change in these variables and NeX did not have any additional effect over exercise alone. In the 3 groups, (1) OT time dropped similarly (bed rest p < 0.001), (2) HR and ΣI were increased at rest at the end of HDBR and HR increased markedly during LBNP-tilt test, with inability to increase further the ΣI, (3) PV dropped (bed rest p < 0.001), along with LVEDV, LVESV and SV (p = 0.08, p < 0.001, and p = 0.045, respectively), (4) Left ventricle mass did not change significantly, (5) Deformation of the heart assessed by global circumferential strain was preserved and early diastolic circumferential strain rate was increased during orthostatic stress at the end of HDBR, illustrating preserved systolic and diastolic function respectively, without any difference between groups. Despite the drop in PV and LV volumes, RVE and NeX tended to alleviate the decrease in VO2max. In conclusion, RVE and NeX failed to prevent the cardiovascular deconditioning induced by a 21 day-HDBR.
Collapse
Affiliation(s)
- Patrick Guinet
- Département d’Anesthésie Réanimation, Centre Hospitalier Universitaire de Rennes, Rennes, France
- Centre Hospitalier de Fougères, Fougères, France
| | - James Patrick MacNamara
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | | | - Françoise Larcher
- Laboratoire de Biochimie, Centre Hospitalier Universitaire d’Angers, Angers, France
| | | | - Marc-Antoine Custaud
- Centre de Recherche Clinique, Centre Hospitalier Universitaire d’Angers, Angers, France
- Mitovasc UMR INSERM 1083-CNRS 6015, Université d’Angers, Angers, France
| | - Anne Pavy-Le Traon
- Department of Neurology, French Reference Center for MSA, University Hospital of Toulouse, Toulouse, France
- Institute of Cardiovascular and Metabolic Diseases INSERM U 1048, Toulouse, France
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Nastassia Navasiolava
- Centre de Recherche Clinique, Centre Hospitalier Universitaire d’Angers, Angers, France
- Mitovasc UMR INSERM 1083-CNRS 6015, Université d’Angers, Angers, France
| |
Collapse
|
11
|
Zhang LF, Hargens AR. Spaceflight-Induced Intracranial Hypertension and Visual Impairment: Pathophysiology and Countermeasures. Physiol Rev 2017; 98:59-87. [PMID: 29167331 DOI: 10.1152/physrev.00017.2016] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 05/25/2017] [Accepted: 05/26/2017] [Indexed: 12/21/2022] Open
Abstract
Visual impairment intracranial pressure (VIIP) syndrome is considered an unexplained major risk for future long-duration spaceflight. NASA recently redefined this syndrome as Spaceflight-Associated Neuro-ocular Syndrome (SANS). Evidence thus reviewed supports that chronic, mildly elevated intracranial pressure (ICP) in space (as opposed to more variable ICP with posture and activity on Earth) is largely accounted for by loss of hydrostatic pressures and altered hemodynamics in the intracranial circulation and the cerebrospinal fluid system. In space, an elevated pressure gradient across the lamina cribrosa, caused by a chronic but mildly elevated ICP, likely elicits adaptations of multiple structures and fluid systems in the eye which manifest themselves as the VIIP syndrome. A chronic mismatch between ICP and intraocular pressure (IOP) in space may acclimate the optic nerve head, lamina cribrosa, and optic nerve subarachnoid space to a condition that is maladaptive to Earth, all contributing to the pathogenesis of space VIIP syndrome. Relevant findings help to evaluate whether artificial gravity is an appropriate countermeasure to prevent this seemingly adverse effect of long-duration spaceflight.
Collapse
Affiliation(s)
- Li-Fan Zhang
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an, China; and Department of Orthopaedic Surgery, University of California, San Diego, California
| | - Alan R Hargens
- Department of Aerospace Physiology, Fourth Military Medical University, Xi'an, China; and Department of Orthopaedic Surgery, University of California, San Diego, California
| |
Collapse
|
12
|
Ried-Larsen M, Aarts HM, Joyner MJ. Effects of strict prolonged bed rest on cardiorespiratory fitness: systematic review and meta-analysis. J Appl Physiol (1985) 2017; 123:790-799. [DOI: 10.1152/japplphysiol.00415.2017] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 06/29/2017] [Accepted: 07/07/2017] [Indexed: 12/29/2022] Open
Abstract
The aim of this systematic review and meta-analysis [International Prospective Register of Systematic Reviews (PROSPERO) CRD42017055619] was to assess the effects of strict prolonged bed rest (without countermeasures) on maximal oxygen uptake (V̇o2max) and to explore sources of variation therein. Since 1949, 80 studies with a total of 949 participants (>90% men) have been published with data on strict bed rest and V̇o2max. The studies were conducted mainly in young participants [median age (interquartile range) 24.5 (22.4–34.0) yr]. The duration of bed rest ranged from 1 to 90 days. V̇o2max declined linearly across bed rest duration. No statistical difference in the decline among studies reporting V̇o2max as l/min (−0.3% per day) compared with studies reporting V̇o2max normalized to body weight (ml·kg−1·min−1; −0.43% per day) was observed. Although both total body weight and lean body mass declined in response to bed rest, we did not see any associations with the decline in V̇o2max. However, 15–26% of the variation in the decline in V̇o2max was explained by the pre-bed-rest V̇o2max levels, independent of the duration of bed rest (i.e., higher pre-bed-rest V̇o2max levels were associated with larger declines in V̇o2max). Furthermore, the systematic review revealed a gap in the knowledge about the cardiovascular response to extreme physical inactivity, particularly in older subjects and women of any age group. In addition to its relevance to spaceflight, this lack of data has significant translational implications because younger women sometimes undergo prolonged periods of bed rest associated with the complications of pregnancy and the incidence of hospitalization including prolonged periods of bed rest increases with age. NEW & NOTEWORTHY Large interindividual responses of maximal oxygen uptake (V̇o2max) to aerobic exercise training exist. However, less is known about the variability in the response of V̇o2max to prolonged bed rest. This systematic review and meta-analysis showed that pre-bed-rest V̇o2max values were inversely associated with the change in V̇o2max independent of the duration of bed rest. Moreover, we identified a large knowledge gap about the causes of decline in V̇o2max, particularly in postmenopausal women, which may have clinical implications.
Collapse
Affiliation(s)
- Mathias Ried-Larsen
- Centre for Physical Activity Research, Rigshospitalet, Copenhagen, Denmark; and
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Hugo M. Aarts
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Michael J. Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| |
Collapse
|
13
|
LI XT, YANG CB, ZHU YS, SUN J, SHI F, WANG YC, GAO Y, ZHAO JD, SUN XQ. Moderate Exercise Based on Artificial Gravity Preserves Orthostatic Tolerance and Exercise Capacity During Short-Term Head-Down Bed Rest. Physiol Res 2017; 66:567-580. [DOI: 10.33549/physiolres.933493] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Numerous countermeasures have been proposed to minimize microgravity-induced physical deconditioning, but their benefits are limited. The present study aimed to investigate whether personalized aerobic exercise based on artificial gravity (AG) mitigates multisystem physical deconditioning. Fourteen men were assigned to the control group (n=6) and the countermeasure group (CM, n=8). Subjects in the CM group were exposed to AG (2 Gz at foot level) for 30 min twice daily, during which time cycling exercise of 80-95 % anaerobic threshold (AT) intensity was undertaken. Orthostatic tolerance (OT), exercise tests, and blood assays were determined before and after 4 days head-down bed rest (HDBR). Cardiac systolic function was measured every day. After HDBR, OT decreased to 50.9 % and 77.5 % of pre-HDBR values in control and CM groups, respectively. Exercise endurance, maximal oxygen consumption, and AT decreased to 96.5 %, 91.5 % and 91.8 % of pre-HDBR values, respectively, in the control group. Nevertheless, there were slight changes in the CM group. HDBR increased heart rate, sympathetic activity, and the pre-ejection period, but decreased plasma volume, parasympathetic activity and left-ventricular ejection time in the control group, whereas these effects were eliminated in the CM group. Aldosterone had no change in the control group but increased significantly in the CM group. Our study shows that 80-95 % AT aerobic exercise based on 2 Gz of AG preserves OT and exercise endurance, and affects body fluid regulation during short-term HDBR. The underlying mechanisms might involve maintained cardiac systolic function, preserved plasma volume, and improved sympathetic responses to orthostatic stress.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - X.-Q. SUN
- Department of Aerospace Biodynamics, Faculty of Aerospace Medicine, Fourth Military Medical University, Xi’an, China
| |
Collapse
|
14
|
Heer M, Baecker N, Frings-Meuthen P, Graf S, Zwart SR, Biolo G, Smith SM. Effects of high-protein intake on bone turnover in long-term bed rest in women. Appl Physiol Nutr Metab 2017; 42:537-546. [DOI: 10.1139/apnm-2016-0292] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Bed rest (BR) causes bone loss, even in otherwise healthy subjects. Several studies suggest that ambulatory subjects may benefit from high-protein intake to stimulate protein synthesis and to maintain muscle mass. However, increasing protein intake above the recommended daily intake without adequate calcium and potassium intake may increase bone resorption. We hypothesized that a regimen of high-protein intake (HiPROT), applied in an isocaloric manner during BR, with calcium and potassium intake meeting recommended values, would prevent any effect of BR on bone turnover. After a 20-day ambulatory adaptation to a controlled environment, 16 women participated in a 60-day, 6° head-down-tilt (HDT) BR and were assigned randomly to 1 of 2 groups. Control (CON) subjects (n = 8) received 1 g/(kg body mass·day)−1 dietary protein. HiPROT subjects (n = 8) received 1.45 g protein/(kg body mass·day)−1 plus an additional 0.72 g branched-chain amino acids per day during BR. All subjects received an individually tailored diet (before HDTBR: 1888 ± 98 kcal/day; during HDTBR: 1604 ± 125 kcal/day; after HDTBR: 1900 ± 262 kcal/day), with the CON group’s diet being higher in fat and carbohydrate intake. High-protein intake exacerbated the BR-induced increase in bone resorption marker C-telopeptide (>30%) (p < 0.001) by the end of BR. Bone formation markers were unaffected by BR and high-protein intake. We conclude that high-protein intake in BR might increase bone loss. Further long-duration studies are mandatory to show how the positive effect of protein on muscle mass can be maintained without the risk of reducing bone mineral density.
Collapse
Affiliation(s)
- Martina Heer
- Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, 53115 Bonn, Germany
| | - Natalie Baecker
- Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, 53115 Bonn, Germany
| | - Petra Frings-Meuthen
- German Aerospace Center (DLR), Institute of Aerospace Medicine, 51147 Cologne, Germany
| | - Sonja Graf
- Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, 53115 Bonn, Germany
| | - Sara R. Zwart
- University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Gianni Biolo
- Department of Clinical, Technological and Morphological Sciences, Division of Internal Medicine, University of Trieste, 34127 Trieste, Italy
| | - Scott M. Smith
- Human Health and Performance Directorate, NASA Lyndon B. Johnson Space Center, Houston, TX 77058, USA
| |
Collapse
|
15
|
Schneider SM, Lee SMC, Feiveson AH, Watenpaugh DE, Macias BR, Hargens AR. Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest. Physiol Rep 2017; 4:4/15/e12892. [PMID: 27495299 PMCID: PMC4985554 DOI: 10.14814/phy2.12892] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 07/19/2016] [Indexed: 01/26/2023] Open
Abstract
Leg muscle mass and strength are decreased during reduced activity and non‐weight‐bearing conditions such as bed rest (BR) and spaceflight. Supine treadmill exercise within lower body negative pressure (LBNPEX) provides full‐body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40‐min interval exercise protocol performed against LBNPEX 6 days week−1 would attenuate losses in leg lean mass (LLM), strength, and endurance during 6° head‐down tilt BR, with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non‐exercise control (CON) and the other twin as the exercise subject (EX). Before and after BR, LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre‐ to post‐BR in the male CON subjects (P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre‐ to post‐BR changes were significant in the female subjects, either CON or EX, likely due to their lower pre‐BR values. Importantly, the LBNPEX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit.
Collapse
Affiliation(s)
| | - Stuart M C Lee
- Wyle Science, Technology, and Engineering Group, Houston, Texas
| | | | | | | | | |
Collapse
|
16
|
Ade CJ, Broxterman RM, Moore AD, Barstow TJ. Decreases in maximal oxygen uptake following long-duration spaceflight: Role of convective and diffusive O 2 transport mechanisms. J Appl Physiol (1985) 2017; 122:968-975. [PMID: 28153941 DOI: 10.1152/japplphysiol.00280.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 12/19/2016] [Accepted: 01/19/2017] [Indexed: 01/22/2023] Open
Abstract
We have previously predicted that the decrease in maximal oxygen uptake (V̇o2max) that accompanies time in microgravity reflects decrements in both convective and diffusive O2 transport to the mitochondria of the contracting myocytes. The aim of this investigation was therefore to quantify the relative changes in convective O2 transport (Q̇o2) and O2 diffusing capacity (Do2) following long-duration spaceflight. In nine astronauts, resting hemoglobin concentration ([Hb]), V̇o2max, maximal cardiac output (Q̇Tmax), and differences in arterial and venous O2 contents ([Formula: see text]-[Formula: see text]) were obtained retrospectively for International Space Station Increments 19-33 (April 2009-November 2012). Q̇o2 and Do2 were calculated from these variables via integration of Fick's Principle of Mass Conservation and Fick's Law of Diffusion. V̇o2max significantly decreased from pre- to postflight (-53.9 ± 45.5%, P = 0.008). The significant decrease in Q̇Tmax (-7.8 ± 9.1%, P = 0.05), despite an unchanged [Hb], resulted in a significantly decreased Q̇o2 (-11.4 ± 10.5%, P = 0.02). Do2 significantly decreased from pre- to postflight by -27.5 ± 24.5% (P = 0.04), as did the peak [Formula: see text]-[Formula: see text] (-9.2 ± 7.5%, P = 0.007). With the use of linear regression analysis, changes in V̇o2max were significantly correlated with changes in Do2 (R2 = 0.47; P = 0.04). These data suggest that spaceflight decreases both convective and diffusive O2 transport. These results have practical implications for future long-duration space missions and highlight the need to resolve the specific mechanisms underlying these spaceflight-induced changes along the O2 transport pathway.NEW & NOTEWORTHY Long-duration spaceflight elicited a significant decrease in maximal oxygen uptake. Given the adverse physiological adaptations to microgravity along the O2 transport pathway that have been reported, an integrative approach to the determinants of postflight maximal oxygen uptake is needed. We demonstrate that both convective and diffusive oxygen transport are decreased following ~6 mo International Space Station missions.
Collapse
Affiliation(s)
- C J Ade
- Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma; .,Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - R M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - A D Moore
- Department of Health and Kinesiology, Lamar University, Beaumont, Texas; and
| | - T J Barstow
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| |
Collapse
|
17
|
Macaulay TR, Macias BR, Lee SM, Boda WL, Watenpaugh DE, Hargens AR. Treadmill exercise within lower-body negative pressure attenuates simulated spaceflight-induced reductions of balance abilities in men but not women. NPJ Microgravity 2016; 2:16022. [PMID: 28725733 PMCID: PMC5515523 DOI: 10.1038/npjmgrav.2016.22] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 11/09/2022] Open
Abstract
Spaceflight causes sensorimotor adaptations that result in balance deficiencies on return to a gravitational environment. Treadmill exercise within lower-body negative pressure (LBNP) helps protect physiological function during microgravity as simulated by bed rest. Therefore, we hypothesized that treadmill exercise within LBNP would prevent balance losses in both male and female identical twins during 30 days of 6° head-down tilt bed rest. Fifteen (seven female and eight male) identical twin sets participated in this simulation of microgravity. Within each twin pair, one twin was randomly assigned to an exercise group that performed 40 min of supine treadmill exercise within LBNP set to generate 1.0–1.2 body weight, followed by 5 min of static feet-supported LBNP, 6 days per week. Their identical sibling was assigned to a non-exercise control group with all other bed rest conditions equivalent. Before and immediately after bed rest, subjects completed standing and walking rail balance tests with eyes open and eyes closed. In control subjects, standing rail balance times (men: −42%, women: −40%), rail walk distances (men: −44%, women: −32%) and rail walk times (men: −34%, women: −31%) significantly decreased after bed rest. Compared with controls, treadmill exercise within LBNP significantly attenuated losses of standing rail balance time by 63% in men, but the 41% attenuation in women was not significant. Treadmill exercise within LBNP did not affect rail walk abilities in men or women. Treadmill exercise within LBNP during simulated spaceflight attenuates loss of balance control in men but not in women.
Collapse
Affiliation(s)
- Timothy R Macaulay
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, USA
| | - Brandon R Macias
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, USA
| | - Stuart Mc Lee
- Cardiovascular Laboratory, Wyle Science, Technology and Engineering Group, Houston, TX, USA
| | - Wanda L Boda
- Department of Kinesiology, Sonoma State University, Rohnert Park, CA, USA
| | - Donald E Watenpaugh
- Department of Integrated Physiology, University of North Texas, Fort Worth, TX, USA
| | - Alan R Hargens
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, CA, USA
| |
Collapse
|
18
|
Holt JA, Macias BR, Schneider SM, Watenpaugh DE, Lee SMC, Chang DG, Hargens AR. WISE 2005: Aerobic and resistive countermeasures prevent paraspinal muscle deconditioning during 60-day bed rest in women. J Appl Physiol (1985) 2016; 120:1215-22. [DOI: 10.1152/japplphysiol.00532.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 02/16/2016] [Indexed: 11/22/2022] Open
Abstract
Microgravity-induced lumbar paraspinal muscle deconditioning may contribute to back pain commonly experienced by astronauts and may increase the risk of postflight injury. We hypothesized that a combined resistive and aerobic exercise countermeasure protocol that included spinal loading would mitigate lumbar paraspinal muscle deconditioning during 60 days of bed rest in women. Sixteen women underwent 60-day, 6° head-down-tilt bed rest (BR) and were randomized into control and exercise groups. During bed rest the control group performed no exercise. The exercise group performed supine treadmill exercise within lower body negative pressure (LBNP) for 3-4 days/wk and flywheel resistive exercise for 2–3 days/wk. Paraspinal muscle cross-sectional area (CSA) was measured using a lumbar spine MRI sequence before and after BR. In addition, isokinetic spinal flexion and extension strengths were measured before and after BR. Data are presented as means ± SD. Total lumbar paraspinal muscle CSA decreased significantly more in controls (10.9 ± 3.4%) than in exercisers (4.3 ± 3.4%; P < 0.05). The erector spinae was the primary contributor (76%) to total lumbar paraspinal muscle loss. Moreover, exercise attenuated isokinetic spinal extension loss (−4.3 ± 4.5%), compared with controls (−16.6 ± 11.2%; P < 0.05). In conclusion, LBNP treadmill and flywheel resistive exercises during simulated microgravity mitigate decrements in lumbar paraspinal muscle structure and spine function. Therefore spaceflight exercise countermeasures that attempt to reproduce spinal loads experienced on Earth may mitigate spinal deconditioning during long-duration space travel.
Collapse
Affiliation(s)
- Jacquelyn A. Holt
- Department of Orthopaedic Surgery, University of California, San Diego, California
| | - Brandon R. Macias
- Department of Orthopaedic Surgery, University of California, San Diego, California
| | | | - Donald E. Watenpaugh
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas; and
| | | | - Douglas G. Chang
- Department of Orthopaedic Surgery, University of California, San Diego, California
| | - Alan R. Hargens
- Department of Orthopaedic Surgery, University of California, San Diego, California
| |
Collapse
|
19
|
Ade CJ, Broxterman RM, Barstow TJ. VO(2max) and Microgravity Exposure: Convective versus Diffusive O(2) Transport. Med Sci Sports Exerc 2016; 47:1351-61. [PMID: 25380479 DOI: 10.1249/mss.0000000000000557] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Exposure to a microgravity environment decreases the maximal rate of O2 uptake (VO(2max)) in healthy individuals returning to a gravitational environment. The magnitude of this decrease in VO(2max) is, in part, dependent on the duration of microgravity exposure, such that long exposure may result in up to a 38% decrease in VO(2max). This review identifies the components within the O(2) transport pathway that determine the decrease in postmicrogravity VO(2max) and highlights the potential contributing physiological mechanisms. A retrospective analysis revealed that the decline in VO(2max) is initially mediated by a decrease in convective and diffusive O(2) transport that occurs as the duration of microgravity exposure is extended. Mechanistically, the attenuation of O(2) transport is the combined result of a deconditioning across multiple organ systems including decreases in total blood volume, red blood cell mass, cardiac function and mass, vascular function, skeletal muscle mass, and, potentially, capillary hemodynamics, which become evident during exercise upon re-exposure to the head-to-foot gravitational forces of upright posture on Earth. In summary, VO(2max) is determined by the integration of central and peripheral O(2) transport mechanisms, which, if not maintained during microgravity, will have a substantial long-term detrimental impact on space mission performance and astronaut health.
Collapse
Affiliation(s)
- Carl J Ade
- 1Department of Health and Exercise Science, University of Oklahoma, Norman, OK; 2Department of Kinesiology, Kansas State University, Manhattan, KS; and 3Department of Anatomy and Physiology, Kansas State University, Manhattan, KS
| | | | | |
Collapse
|
20
|
Hargens AR, Vico L. Long-duration bed rest as an analog to microgravity. J Appl Physiol (1985) 2016; 120:891-903. [PMID: 26893033 DOI: 10.1152/japplphysiol.00935.2015] [Citation(s) in RCA: 183] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 02/12/2016] [Indexed: 11/22/2022] Open
Abstract
Long-duration bed rest is widely employed to simulate the effects of microgravity on various physiological systems, especially for studies of bone, muscle, and the cardiovascular system. This microgravity analog is also extensively used to develop and test countermeasures to microgravity-altered adaptations to Earth gravity. Initial investigations of bone loss used horizontal bed rest with the view that this model represented the closest approximation to inactivity and minimization of hydrostatic effects, but all Earth-based analogs must contend with the constant force of gravity by adjustment of the G vector. Later concerns about the lack of similarity between headward fluid shifts in space and those with horizontal bed rest encouraged the use of 6 degree head-down tilt (HDT) bed rest as pioneered by Russian investigators. Headward fluid shifts in space may redistribute bone from the legs to the head. At present, HDT bed rest with normal volunteers is the most common analog for microgravity simulation and to test countermeasures for bone loss, muscle and cardiac atrophy, orthostatic intolerance, and reduced muscle strength/exercise capacity. Also, current physiologic countermeasures are focused on long-duration missions such as Mars, so in this review we emphasize HDT bed rest studies with durations of 30 days and longer. However, recent results suggest that the HDT bed rest analog is less representative as an analog for other important physiological problems of long-duration space flight such as fluid shifts, spinal dysfunction and radiation hazards.
Collapse
Affiliation(s)
- Alan R Hargens
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California; and Institut National de la Santé et de la Recherche Médicale Unité 1059, University of Lyon, St-Etienne, France
| | - Laurence Vico
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California; and Institut National de la Santé et de la Recherche Médicale Unité 1059, University of Lyon, St-Etienne, France
| |
Collapse
|
21
|
Clément GR, Bukley AP, Paloski WH. Artificial gravity as a countermeasure for mitigating physiological deconditioning during long-duration space missions. Front Syst Neurosci 2015; 9:92. [PMID: 26136665 PMCID: PMC4470275 DOI: 10.3389/fnsys.2015.00092] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 05/30/2015] [Indexed: 11/21/2022] Open
Abstract
In spite of the experience gained in human space flight since Yuri Gagarin’s historical flight in 1961, there has yet to be identified a completely effective countermeasure for mitigating the effects of weightlessness on humans. Were astronauts to embark upon a journey to Mars today, the 6-month exposure to weightlessness en route would leave them considerably debilitated, even with the implementation of the suite of piece-meal countermeasures currently employed. Continuous or intermittent exposure to simulated gravitational states on board the spacecraft while traveling to and from Mars, also known as artificial gravity, has the potential for enhancing adaptation to Mars gravity and re-adaptation to Earth gravity. Many physiological functions are adversely affected by the weightless environment of spaceflight because they are calibrated for normal, Earth’s gravity. Hence, the concept of artificial gravity is to provide a broad-spectrum replacement for the gravitational forces that naturally occur on the Earth’s surface, thereby avoiding the physiological deconditioning that takes place in weightlessness. Because researchers have long been concerned by the adverse sensorimotor effects that occur in weightlessness as well as in rotating environments, additional study of the complex interactions among sensorimotor and other physiological systems in rotating environments must be undertaken both on Earth and in space before artificial gravity can be implemented.
Collapse
|
22
|
Lee SMC, Schneider SM, Feiveson AH, Macias BR, Smith SM, Watenpaugh DE, Hargens AR. WISE-2005: Countermeasures to prevent muscle deconditioning during bed rest in women. J Appl Physiol (1985) 2014; 116:654-67. [PMID: 24458754 DOI: 10.1152/japplphysiol.00590.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The objectives of this study were to evaluate the efficacy of two separate countermeasures, exercise and protein supplementation, to prevent muscle strength and lean tissue mass losses during 60 days of bed rest (BR) in women and whether countermeasure efficacy was influenced by pre-BR muscular fitness (strength, endurance, tissue mass). Twenty-four women were assigned to an exercise (EX, n = 8), a no-exercise control (CON, n = 8), or a no-exercise protein supplementation group (PROT, n = 8). EX performed supine treadmill exercise within lower body negative pressure 3-4 days/wk and maximal concentric and eccentric supine leg- and calf-press exercises 2-4 days/wk. PROT consumed a diet with elevated protein content compared with CON and EX (1.6 vs. 1.0 g·kg(-1)·day(-1)). Knee and calf isokinetic strength and endurance, isotonic leg-press strength, and leg lean mass were measured before and after BR. Post-BR knee extensor strength and endurance, ankle strength, and leg lean mass were significantly greater and leg-press strength tended to be higher in EX than in CON and PROT. Post-BR measures in PROT were not different than those in CON. Exercise countermeasure efficacy was less, and strength, endurance, and leg lean mass losses in CON and PROT were greater, in subjects who were more fit pre-BR. An exercise protocol combining resistive and aerobic exercise training protects against losses in strength, endurance, and leg lean mass in women during BR, while a nutritional countermeasure without exercise was not effective. Exercise countermeasures may require individualization to protect higher levels of strength and endurance.
Collapse
Affiliation(s)
- Stuart M C Lee
- Wyle Science, Technology, and Engineering Group, Houston, Texas
| | | | | | | | | | | | | |
Collapse
|
23
|
Adami A, Pizzinelli P, Bringard A, Capelli C, Malacarne M, Lucini D, Simunič B, Pišot R, Ferretti G. Cardiovascular re-adjustments and baroreflex response during clinical reambulation procedure at the end of 35-day bed rest in humans. Appl Physiol Nutr Metab 2013; 38:673-80. [DOI: 10.1139/apnm-2012-0396] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the reambulation procedure after 35-day head-down tilt bed rest (HDTBR) for 9 men, we recorded for the first time heart rate (HR; with electrocardiogram) and arterial pressure profiles (fingertip plethysmography) for 5 min in HDTBR and horizontal (SUP) positions, followed by 12 min in standing position, during which 4 subjects fainted (intolerant, INT) and were laid horizontal again (Recovery). We computed: mean arterial pressure (P¯; pressure profiles integral mean), stroke volume (SV; obtained with Modelflow method), and cardiac output (Q̇; SV × HR). All cardiovascular data remained stable in HDTBR and SUP for both groups (EXP). Taking the upright posture, EXP showed a decrease in SV and an increase in HR, becoming significantly different from SUP within 1 min. Further evolution of these parameters kept Q̇ stable in both groups until the second minute of standing. Afterward, in INT, P̄ precipitated without further HR increases: SV stopped being corrected and Q̇ reached 2.9 ± 0.4 L·min−1 at the last 15 s of standing. Sudden drop in P̄ allowed identification of a low-pressure threshold in INT (70.7 ± 12.9 mm Hg), after which syncope occurred within 80 s. During Recovery, baroreflex curves showed a flat phase (P̄ increase, HR stable), followed by a steep phase (P̄ increased, HR decreased, starting when P̄ was 84.5 ± 12.5 mm Hg and Q̇ was 9.6 ± 1.5 L·min−1). INT, in contrast with tolerant subjects, did not sustain standing because HR was unable to correct for the P̄ drop. These results indicate a major role for impaired arterial baroreflexes in the onset of orthostatic intolerance.
Collapse
Affiliation(s)
- Alessandra Adami
- Département de Neuroscience Fondamentales, Centre Médical Universitaire, Université de Genève, 1 Rue Michel Servet, CH-1211 Genève 4, Switzerland
| | - Paolo Pizzinelli
- Dipartimento di Scienze Cliniche, Ospedale L. Sacco, Università di Milano, via GB. Grassi 74, Milano, Italia
| | - Aurélien Bringard
- Département de Neuroscience Fondamentales, Centre Médical Universitaire, Université de Genève, 1 Rue Michel Servet, CH-1211 Genève 4, Switzerland
| | - Carlo Capelli
- Dipartimento di Scienze Neurologiche, Neuropsicologiche, Morfologiche e Motorie, Facoltà di Scienze Motorie, Università di Verona, via F. Casorati, 54, 37100 Verona, Italia
| | - Mara Malacarne
- Dipartimento di Scienze Cliniche, Ospedale L. Sacco, Università di Milano, via GB. Grassi 74, Milano, Italia
| | - Daniela Lucini
- Dipartimento di Scienze Cliniche, Ospedale L. Sacco, Università di Milano, via GB. Grassi 74, Milano, Italia
| | - Boštjan Simunič
- Institute of Kinesiology Research, Science and Research Center, University of Primorska, Koper, Garibaldijeva street 1, 6000 Koper, Slovenia
| | - Rado Pišot
- Institute of Kinesiology Research, Science and Research Center, University of Primorska, Koper, Garibaldijeva street 1, 6000 Koper, Slovenia
| | - Guido Ferretti
- Département de Neuroscience Fondamentales, Centre Médical Universitaire, Université de Genève, 1 Rue Michel Servet, CH-1211 Genève 4, Switzerland
- Dipartimento di Scienze Biomediche e Biotecnologie, Facoltà di Medicina, Università di Brescia, Viale Europa 11, 25123 Brescia, Italia
| |
Collapse
|
24
|
Zhang LF. Region-specific vascular remodeling and its prevention by artificial gravity in weightless environment. Eur J Appl Physiol 2013; 113:2873-95. [DOI: 10.1007/s00421-013-2597-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 01/20/2013] [Indexed: 10/27/2022]
|
25
|
Zuj KA, Arbeille P, Shoemaker JK, Hughson RL. Cerebral critical closing pressure and CO2 responses during the progression toward syncope. J Appl Physiol (1985) 2013; 114:801-7. [DOI: 10.1152/japplphysiol.01181.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Syncope from sustained orthostasis results from cerebral hypoperfusion associated with reductions in arterial pressure at the level of the brain (BPMCA) and reductions in arterial CO2 as reflected by end-tidal values (PetCO2). It was hypothesized that reductions in PetCO2 increase cerebrovascular tone before a drop in BPMCA that ultimately leads to syncope. Twelve men (21–42 yr of age) completed an orthostatic tolerance test consisting of head-up tilt and progressive lower body negative pressure to presyncope, before and after completing 5 days of continuous head-down bed rest (HDBR). Cerebral blood velocity (CBFV), BPMCA, and PetCO2 were continuously recorded throughout the test. Cerebrovascular indicators, cerebrovascular resistance, critical closing pressure (CrCP), and resistance area product (RAP), were calculated. Comparing from supine baseline to 6–10 min after the start of tilt, there were reductions in CBFV, PetCO2, BPMCA, and CrCP, an increase in RAP, and no change in cerebrovascular resistance index. Over the final 15 min before syncope in the pre-HDBR tests, CBFV and CrCP were significantly related to changes in PetCO2 ( r = 0.69 ± 0.17 and r = 0.63 ± 0.20, respectively), and BPMCA, which was not reduced until the last minute of the test, was correlated with a reduction in RAP ( r = 0.91 ± 0.09). Post-HDBR, tilt tolerance was markedly reduced, and changes in CBFV were dominated by a greater reduction in BPMCA with no relationships to PetCO2. Therefore, pre-HDBR, changes in PetCO2 with orthostasis contributed to increases in cerebrovascular tone and reductions in CBFV during the progression toward syncope, whereas, after 5 days of HDBR, orthostatic responses were dominated by changes in BPMCA.
Collapse
Affiliation(s)
- K. A. Zuj
- University of Waterloo, Waterloo, Ontario, Canada
| | | | | | | |
Collapse
|
26
|
Hargens AR, Bhattacharya R, Schneider SM. Space physiology VI: exercise, artificial gravity, and countermeasure development for prolonged space flight. Eur J Appl Physiol 2012; 113:2183-92. [DOI: 10.1007/s00421-012-2523-5] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/05/2012] [Indexed: 01/06/2023]
|
27
|
Macias BR, D'Lima DD, Cutuk A, Patil S, Steklov N, Neuschwander TB, Meuche S, Colwell CW, Hargens AR. Leg intramuscular pressures and in vivo knee forces during lower body positive and negative pressure treadmill exercise. J Appl Physiol (1985) 2012; 113:31-8. [DOI: 10.1152/japplphysiol.01434.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Quantifying muscle and joint forces over a broad range of weight bearing loads during exercise may provide data required to improve prosthetic materials and better protect against muscle and bone loss. Collectively, leg intramuscular pressure (IMP), ground reaction force (GRF), and the instrumented tibial tray force measurements provide a comprehensive assessment of leg muscle and joint biomechanical effects of gravity during exercise. Titration of body weight (BW) by lower body negative pressure (LBNP) and lower body positive pressure (LBPP) can reproducibly modulate IMP within leg muscle compartments. In addition, previous studies document peak tibial forces during various daily activities of 2.2 to 2.5 BW. The study objective was to determine the IMPs of the leg, axial compressive force on the tibia in vivo, vertical GRF, and knee range of motion during altered BW levels using LBPP and LBNP treadmill exercise. We hypothesize that peak GRF, peak tibial forces, and peak IMPs of the leg correlate linearly with percent BW, as generated across a broad range of upright LBPP and supine LBNP exercise. When running at 2.24 m/s the leg IMPs significantly increased over the loading range of 60% to 140% BW with LBPP and LBNP ( P < 0.001); as expected, leg IMPs were significantly higher when running compared with standing ( P < 0.001). During upright LBPP, total axial force at the knee increased linearly as a function of BW at 0.67 m/s ( R2 = 0.90) and 1.34 m/s ( R2 = 0.98). During supine LBNP, total axial force at the knee increased linearly as a function of BW at 0.67 m/s ( R2 = 0.98) and 1.34 m/s ( R2 = 0.91). The present study is the first to measure IMPs and peak tibial forces in vivo during upright LBPP, upright LBNP, and supine LBNP exercise. These data will aid the development of rehabilitation exercise hardware and prescriptions for patients and astronauts.
Collapse
Affiliation(s)
- Brandon R. Macias
- Department of Health and Kinesiology, Texas A&M University, College Station, Texas
| | - Darryl D. D'Lima
- Orthopaedic Research Laboratories, Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, California; and
| | - Adnan Cutuk
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California
| | - Shantanu Patil
- Orthopaedic Research Laboratories, Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, California; and
| | - Nick Steklov
- Orthopaedic Research Laboratories, Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, California; and
| | - Timothy B. Neuschwander
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California
| | - Sabine Meuche
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California
| | - Clifford W. Colwell
- Orthopaedic Research Laboratories, Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, California; and
| | - Alan R. Hargens
- Department of Orthopaedic Surgery, University of California, San Diego, San Diego, California
| |
Collapse
|
28
|
Aletti F, Ferrario M, Xu D, Greaves DK, Shoemaker JK, Arbeille P, Baselli G, Hughson RL. Short-term variability of blood pressure: effects of lower-body negative pressure and long-duration bed rest. Am J Physiol Regul Integr Comp Physiol 2012; 303:R77-85. [DOI: 10.1152/ajpregu.00050.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mild lower-body negative pressure (LBNP) has been utilized to selectively unload cardiopulmonary baroreceptors, but there is evidence that arterial baroreceptors can be transiently unloaded after the onset of mild LBNP. In this paper, a black box mathematical model for the prediction of diastolic blood pressure (DBP) variability from multiple inputs (systolic blood pressure, R-R interval duration, and central venous pressure) was applied to interpret the dynamics of blood pressure maintenance under the challenge of LBNP and in long-duration, head-down bed rest (HDBR). Hemodynamic recordings from seven participants in the WISE (Women's International Space Simulation for Exploration) Study collected during an experiment of incremental LBNP (−10 mmHg, −20 mmHg, −30 mmHg) were analyzed before and on day 50 of a 60-day-long HDBR campaign. Autoregressive spectral analysis focused on low-frequency (LF, ∼0.1 Hz) oscillations of DBP, which are related to fluctuations in vascular resistance due to sympathetic and baroreflex regulation of vasomotor tone. The arterial baroreflex-related component explained 49 ± 13% of LF variability of DBP in spontaneous conditions, and 89 ± 9% ( P < 0.05) on day 50 of HDBR, while the cardiopulmonary baroreflex component explained 17 ± 9% and 12 ± 4%, respectively. The arterial baroreflex-related variability was significantly increased in bed rest also for LBNP equal to −20 and −30 mmHg. The proposed technique provided a model interpretation of the proportional effect of arterial baroreflex vs. cardiopulmonary baroreflex-mediated components of blood pressure control and showed that arterial baroreflex was the main player in the mediation of DBP variability. Data during bed rest suggested that cardiopulmonary baroreflex-related effects are blunted and that blood pressure maintenance in the presence of an orthostatic stimulus relies mostly on arterial control.
Collapse
Affiliation(s)
- Federico Aletti
- Dipartimento di Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Manuela Ferrario
- Dipartimento di Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Da Xu
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Danielle K. Greaves
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - J. Kevin Shoemaker
- School of Kinesiology, University of Western Ontario, London, Ontario, Canada; and
| | - Philippe Arbeille
- Unité Médecine et Physiologie Spatiale CEntre de Recherche COeur et Maladies vasculaires, University Hospital Trousseau, Tours, France
| | - Giuseppe Baselli
- Dipartimento di Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Richard L. Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
29
|
Zuj KA, Edgell H, Shoemaker JK, Custaud MA, Arbeille P, Hughson RL. WISE 2005: responses of women to sublingual nitroglycerin before and after 56 days of 6° head-down bed rest. J Appl Physiol (1985) 2012; 113:434-41. [PMID: 22653986 DOI: 10.1152/japplphysiol.00445.2012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study tested the hypothesis that cardiovascular effects of sublingual nitroglycerin (NG) would be exaggerated after 56 days of 6° head-down bed rest (HDBR) in women, and that an aerobic and resistive exercise countermeasure (EX, n = 8) would reduce the effect compared with HDBR without exercise (CON, n = 7). Middle cerebral artery maximal blood flow velocity (CBFV), cardiac stroke volume (SV), and superficial femoral artery blood flow (Doppler ultrasound) were recorded at baseline rest and for 5 min following 0.3 mg sublingual NG. Post-HDBR, NG caused greater increases in heart rate (HR) in CON compared with EX (+24.9 ± 7.7 and +18.8 ± 6.6 beats/min, respectively, P < 0.0001). The increase in HR combined with reductions in SV to maintain cardiac output. Systolic, mean, and pulse pressures were reduced 5-10 mmHg by NG, but total peripheral resistance was only slightly reduced at 3 min after NG. Reductions in CBFV of -12.5 ± 3.8 cm/s were seen after NG, but a reduction in the Doppler resistance index suggested dilation of the middle cerebral artery with no differences after HDBR. The femoral artery dilated with NG and blood flow was reduced ∼50% with the appearance of large negative waves suggesting a marked increase in downstream resistance, but there were no effects of HDBR. In general, responses of women to NG were not altered by HDBR; the greater increase in HR in CON but not EX was probably a consequence of cardiovascular deconditioning. These results contrast with the hypothesis and a previous investigation of men after HDBR by revealing no change in cardiovascular responses to exogenous nitric oxide.
Collapse
Affiliation(s)
- K A Zuj
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | | | | | | | | | | |
Collapse
|
30
|
Hughson RL, Shoemaker JK, Blaber AP, Arbeille P, Greaves DK, Pereira-Junior PP, Xu D. Cardiovascular regulation during long-duration spaceflights to the International Space Station. J Appl Physiol (1985) 2012; 112:719-27. [DOI: 10.1152/japplphysiol.01196.2011] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Early evidence from long-duration flights indicates general cardiovascular deconditioning, including reduced arterial baroreflex gain. The current study investigated the spontaneous baroreflex and markers of cardiovascular control in six male astronauts living for 2–6 mo on the International Space Station. Measurements were made from the finger arterial pressure waves during spontaneous breathing (SB) in the supine posture pre- and postflight and during SB and paced breathing (PB, 0.1 Hz) in a seated posture pre- and postflight, as well as early and late in the missions. There were no changes in preflight measurements of heart rate (HR), blood pressure (BP), or spontaneous baroreflex compared with in-flight measurements. There were, however, increases in the estimate of left ventricular ejection time index and a late in-flight increase in cardiac output (CO). The high-frequency component of RR interval spectral power, arterial pulse pressure, and stroke volume were reduced in-flight. Postflight there was a small increase compared with preflight in HR (60.0 ± 9.4 vs. 54.9 ± 9.6 beats/min in the seated posture, P < 0.05) and CO (5.6 ± 0.8 vs. 5.0 ± 1.0 l/min, P < 0.01). Arterial baroreflex response slope was not changed during spaceflight, while a 34% reduction from preflight in baroreflex slope during postflight PB was significant (7.1 ± 2.4 vs. 13.4 ± 6.8 ms/mmHg), but a smaller average reduction (25%) during SB (8.0 ± 2.1 vs. 13.6 ± 7.4 ms/mmHg) was not significant. Overall, these data show no change in markers of cardiovascular stability during long-duration spaceflight and only relatively small changes postflight at rest in the seated position. The current program routine of countermeasures on the International Space Station provided sufficient stimulus to maintain cardiovascular stability under resting conditions during long-duration spaceflight.
Collapse
Affiliation(s)
- R. L. Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo,
| | - J. K. Shoemaker
- School of Kinesiology and Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario,
| | - A. P. Blaber
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada; and
| | - P. Arbeille
- Unite Medecine Physiologie Spatiale, CERCOM, EFMP CHU Trousseau, Tours, France
| | - D. K. Greaves
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo,
| | | | - D. Xu
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo,
| |
Collapse
|
31
|
Coupé M, Yuan M, Demiot C, Bai YQ, Jiang SZ, Li YZ, Arbeille P, Gauquelin-Koch G, Levrard T, Custaud MA, Li YH. Low-magnitude whole body vibration with resistive exercise as a countermeasure against cardiovascular deconditioning after 60 days of head-down bed rest. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1748-54. [DOI: 10.1152/ajpregu.00234.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Whole body vibration with resistive exercise is a promising countermeasure against some weightlessness-induced dysfunctions. Our objective was to study whether the combination of low-magnitude whole body vibration with a resistive exercise can prevent the cardiovascular deconditioning induced by a nonstrict 60-day head-down bed rest (Earth Star International Bed Rest Experiment Project). Fourteen healthy men participated in this study. We recorded electrocardiograms and blood pressure waves by means of a noninvasive beat-by-beat measurement system (Cardiospace, integrated by Centre National d'Etudes Spatiales and Astronaut Center of China) during an orthostatic test (20 min of 75-degree head-up tilt test) before and immediately after bed rest. We estimated heart rate, blood pressure, cardiac output, stroke volume, total peripheral resistance, baroreflex sensitivity, and heart rate variability. Low-magnitude whole body vibration with resistive exercise prevented an increase of the sympathetic index (reflecting the sympathovagal balance of cardiac autonomic control) and limited the decrease of the spontaneous baroreflex sensitivity induced by 60 days of head-down bed rest. However, this countermeasure had very little effect on cardiac hemodynamics and did not improve the orthostatic tolerance. This combined countermeasure did not efficiently prevent orthostatic intolerance but prevents changes in the autonomic nervous system associated with cardiovascular deconditioning. The underlying mechanisms remain hypothetical but might involve cutaneous and muscular mechanoreceptors.
Collapse
Affiliation(s)
- Mickael Coupé
- UMR CNRS 6214–INSERM 771, Faculté de Médecine d'Angers, Angers, France
| | - Ming Yuan
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Claire Demiot
- EA3842, Homéostasie Cellulaire et Pathologies, Faculté de Pharmacie, Limoges, France
| | - Yanqiang Q. Bai
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Shizhong Z. Jiang
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | - Yongzhi Z. Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| | | | | | - Thibaud Levrard
- Televasc, Centre Hospitalier Universitaire d'Angers, Angers, France
| | | | - Yinghui H. Li
- State Key Laboratory of Space Medicine Fundamentals and Application, China Astronaut Research and Training Center, Beijing, China
| |
Collapse
|
32
|
Arbeille P, Shoemaker K, Kerbeci P, Schneider S, Hargens A, Hughson R. Aortic, cerebral and lower limb arterial and venous response to orthostatic stress after a 60-day bedrest. Eur J Appl Physiol 2011; 112:277-84. [PMID: 21541764 DOI: 10.1007/s00421-011-1935-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 03/17/2011] [Indexed: 10/18/2022]
Abstract
The objective of this study is to assess by echography and Doppler the Cerebral (Vmca), Aortic (Vao) and Femoral (Vfem) arterial flow velocity and calf vein (Tibial, Gastrocnemius) section (Tib, Gast) during orthostatic intolerance (OI) test after a 60-day, head down tilt bed rest (HDBR). Twenty-four women (25-40 years) underwent a 60-day HDBR at -6°: eight as control (Con), eight with exercise against lower body negative pressure (Ex-Lb) and eight with nutrition supplement (Nut). Before and after (R0) HDBR, all subjects underwent a 10-min, 80° tilt followed by progressive LBNP until presyncope. After the post-HDBR Tilt + LBNP test, two groups were identified: finishers (F, n = 11) who completed the Tilt and non-finishers (NF, n = 13). A higher percentage decrease in Vao flow, higher percentage distension of Tib vein and a lack of increase in Vmca/Vfem ratio during the post-HDBR Tilt + LBNP compared to pre-HDBR were correlated to OI, but not all of these abnormal responses were present in each of the NF subjects. Abnormal responses were more frequent in Con and Nut than in Ex-Lb subjects. (1) HDBR did not affect the cardiac, arterial and venous responses to the orthostatic test to the same extent in each subject. (2) Exercise within LBNP partially preserved the cardiovascular response to Tilt, while Nutrition supplementation had no efficacy. (3) Cerebral/femoral flow ratio and aortic flow were the parameters most closely related to OI. (4) Reduction in aortic flow was not the major hemodynamic change preceding syncope.
Collapse
Affiliation(s)
- P Arbeille
- University-CHU Trousseau, Tours, France.
| | | | | | | | | | | |
Collapse
|
33
|
Keller DM, Low DA, Davis SL, Hastings J, Crandall CG. Skin surface cooling improves orthostatic tolerance following prolonged head-down bed rest. J Appl Physiol (1985) 2011; 110:1592-7. [PMID: 21454746 DOI: 10.1152/japplphysiol.00233.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prolonged exposure to microgravity, as well as its ground-based analog, head-down bed rest (HDBR), reduces orthostatic tolerance in humans. While skin surface cooling improves orthostatic tolerance, it remains unknown whether this could be an effective countermeasure to preserve orthostatic tolerance following HDBR. We therefore tested the hypothesis that skin surface cooling improves orthostatic tolerance after prolonged HDBR. Eight subjects (six men and two women) participated in the investigation. Orthostatic tolerance was determined using a progressive lower-body negative pressure (LBNP) tolerance test before HDBR during normothermic conditions and on day 16 or day 18 of 6° HDBR during normothermic and skin surface cooling conditions (randomized order post-HDBR). The thermal conditions were achieved by perfusing water (normothermia ∼34°C and skin surface cooling ∼12-15°C) through a tube-lined suit worn by each subject. Tolerance tests were performed after ∼30 min of the respective thermal stimulus. A cumulative stress index (CSI; mmHg LBNP·min) was determined for each LBNP protocol by summing the product of the applied negative pressure and the duration of LBNP at each stage. HDBR reduced normothermic orthostatic tolerance as indexed by a reduction in the CSI from 1,037 ± 96 mmHg·min to 574 ± 63 mmHg·min (P < 0.05). After HDBR, skin surface cooling increased orthostatic tolerance (797 ± 77 mmHg·min) compared with normothermia (P < 0.05). While the reduction in orthostatic tolerance following prolonged HDBR was not completely reversed by acute skin surface cooling, the identified improvements may serve as an important and effective countermeasure for individuals exposed to microgravity, as well as immobilized and bed-stricken individuals.
Collapse
Affiliation(s)
- David M Keller
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, 7232 Greenville Ave., Dallas, TX 75231, USA
| | | | | | | | | |
Collapse
|
34
|
Effects of acceleration in the Gz axis on human cardiopulmonary responses to exercise. Eur J Appl Physiol 2011; 111:2907-17. [PMID: 21437604 DOI: 10.1007/s00421-011-1917-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 03/08/2011] [Indexed: 10/18/2022]
Abstract
The aim of this paper was to develop a model from experimental data allowing a prediction of the cardiopulmonary responses to steady-state submaximal exercise in varying gravitational environments, with acceleration in the G(z) axis (a (g)) ranging from 0 to 3 g. To this aim, we combined data from three different experiments, carried out at Buffalo, at Stockholm and inside the Mir Station. Oxygen consumption, as expected, increased linearly with a (g). In contrast, heart rate increased non-linearly with a (g), whereas stroke volume decreased non-linearly: both were described by quadratic functions. Thus, the relationship between cardiac output and a (g) was described by a fourth power regression equation. Mean arterial pressure increased with a (g) non linearly, a relation that we interpolated again with a quadratic function. Thus, total peripheral resistance varied linearly with a (g). These data led to predict that maximal oxygen consumption would decrease drastically as a (g) is increased. Maximal oxygen consumption would become equal to resting oxygen consumption when a (g) is around 4.5 g, thus indicating the practical impossibility for humans to stay and work on the biggest Planets of the Solar System.
Collapse
|
35
|
Aletti F, Ferrario M, Xu D, Greaves DK, Shoemaker KJ, Arbeille P, Cerutti S, Hughson RL, Baselli G. System identification of baroreflex response to mild lower body negative pressure. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2011; 2011:2550-2553. [PMID: 22254861 DOI: 10.1109/iembs.2011.6090705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The effect of mild lower body negative pressure (LBNP) on baroreflex control of arterial blood pressure (ABP) has long been thought to affect cardiopulmonary baroreflex only, although recent studies have pointed out that arterial baroreceptors may be transiently unloaded too after the rapid onset of mild LBNP. This paper presents a spectral decomposition method for the black box identification of the contribution of arterial and cardiopulmonary baroreflexes to beat-by-beat variability of ABP in response to mild LBNP levels. The significant decrease of mean and diastolic arterial pressure and of the arterial baroreflex mediated contribution to overall variability of ABP which was found, suggested that the unloading of arterial baroreceptors may be reflected by an altered dynamic response of arterial baroreflex, too. In addition, arterial baroreflex mediated modulations were found to be the main player in the modulation of beat-by-beat fluctuations of ABP, while the role of cardiopulmonary baroreflex mediated responses appeared to contribute very little.
Collapse
Affiliation(s)
- Federico Aletti
- Dipartimento di Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 23, 20133 Milan, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Affiliation(s)
- Michael J Joyner
- Department of Anesthesiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
| |
Collapse
|
37
|
DiVasta AD, Walls CE, Feldman HA, Quach AE, Woods ER, Gordon CM, Alexander ME. Malnutrition and hemodynamic status in adolescents hospitalized for anorexia nervosa. ARCHIVES OF PEDIATRICS & ADOLESCENT MEDICINE 2010; 164:706-13. [PMID: 20679161 PMCID: PMC3205985 DOI: 10.1001/archpediatrics.2010.138] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To determine the effects of malnutrition on hemodynamic status of adolescents hospitalized for anorexia nervosa. DESIGN Longitudinal observational study. SETTING Tertiary care pediatric hospital. Patients Thirty-eight adolescents with anorexia nervosa, aged 13 to 21 years, with a mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) of 15.9 (1.8). Intervention Subjects received standard care, including bed rest and graded nutritional therapy. A subsample of subjects (n=19) returned 11 to 57 weeks following hospitalization for a second cardiac evaluation. MAIN OUTCOME MEASURES Results from a 15-lead electrocardiogram, echocardiogram, treadmill stress test, and spinal bone mineral density measurement. RESULTS On admission, 26 subjects (68%) had sinus bradycardia. Bradycardia was less common in participants with a longer duration of illness (P=.04). Left ventricle mass was lower than predicted for age (Z score<-1.0) in 11 subjects (31%). Exercise tolerance was normal by all measures. Both heart rate and QT interval were predictors of spinal bone mineral density. In those who returned for follow-up, absolute measures of left ventricle mass did not change (P=.27). However, the corresponding Z scores declined over time (mean [SD] change, -0.9 [1.3]; P=.02). CONCLUSIONS In acutely malnourished adolescents with anorexia nervosa, few truly pathologic cardiac findings were identified. Sinus bradycardia was observed in most cases. Mild reductions in left ventricle mass and left ventricle function were seen both at baseline and at follow-up, suggesting early sparing of cardiac muscle in the face of moderate malnutrition as well as a relative delay of cardiac muscle restoration. The association of hemodynamic status with altered spinal bone mineral density emphasizes the range of systems affected by malnutrition in anorexia nervosa.
Collapse
Affiliation(s)
- Amy D DiVasta
- Department of Cardiology, Children's Hospital Boston, 333 Longwood Ave, Boston, MA 02115, USA.
| | | | | | | | | | | | | |
Collapse
|
38
|
Shibata S, Perhonen M, Levine BD. Supine cycling plus volume loading prevent cardiovascular deconditioning during bed rest. J Appl Physiol (1985) 2010; 108:1177-86. [PMID: 20223994 DOI: 10.1152/japplphysiol.01408.2009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There are two possible mechanisms contributing to the excessive fall of stroke volume (and its contribution to orthostatic intolerance) in the upright position after bed rest or spaceflight: reduced cardiac filling due to hypovolemia and/or a less distensible heart due to cardiac atrophy. We hypothesized that preservation of cardiac mechanical function by exercise training, plus normalization of cardiac filling with volume infusion, would prevent orthostatic intolerance after bed rest. Eighteen men and three women were assigned to 1) exercise countermeasure (n=14) and 2) no exercise countermeasure (n=7) groups during bed rest. Bed rest occurred in the 6 degrees head-down tilt position for 18 days. The exercise regimen was prescribed to compensate for the estimated cardiac work reduction between bed rest and ambulatory periods. At the end of bed rest, the subjects were further divided into two additional groups for post-bed rest testing: 1) volume loading with intravenous dextran to normalize cardiac filling pressure and 2) no volume loading. Dextran infusion was given to half of the exercise group and all of the sedentary group after bed rest, leading ultimately to three groups: 1) exercise plus volume infusion; 2) exercise alone; and 3) volume infusion alone. Exercise training alone preserved left ventricular mass and distensibility as well as upright exercise capacity, but lower body negative pressure (LBNP) tolerance was still depressed. LBNP tolerance was maintained only when exercise training was accompanied by dextran infusion. Dextran infusion alone following bed rest without exercise maintained neither orthostatic tolerance nor upright exercise capacity. We conclude that daily supine cycle exercise sufficient to prevent cardiac atrophy can prevent orthostatic intolerance after bed rest only when combined with plasma volume restoration. This maintenance of orthostatic tolerance was achieved by neither exercise nor dextran infusion alone. Cardiac atrophy and hypovolemia are likely to contribute independently to orthostatic intolerance after bed rest.
Collapse
Affiliation(s)
- Shigeki Shibata
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and University of Texas Southwestern Medical Center at Dallas, 7232 Greenville Ave., Suite 435, Dallas, TX 75231, USA
| | | | | |
Collapse
|
39
|
SCHNEIDER SUZANNEM, LEE STUARTMC, MACIAS BRANDONR, WATENPAUGH DONALDE, HARGENS ALANR. WISE-2005. Med Sci Sports Exerc 2009; 41:2165-76. [DOI: 10.1249/mss.0b013e3181aa04e5] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
40
|
Hargens AR, Richardson S. Cardiovascular adaptations, fluid shifts, and countermeasures related to space flight. Respir Physiol Neurobiol 2009; 169 Suppl 1:S30-3. [PMID: 19615471 DOI: 10.1016/j.resp.2009.07.005] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Revised: 06/24/2009] [Accepted: 07/02/2009] [Indexed: 10/20/2022]
Abstract
Significant progress has been made related to understanding cardiovascular adaptations to microgravity and development of countermeasures to improve crew re-adaptation to gravity. The primary ongoing issues are orthostatic intolerance after flight, reduced exercise capacity, the effect of vascular-smooth muscle loss on other physiologic systems, development of efficient and low-cost countermeasures to counteract these losses, and an understanding of fluid shift mechanisms. Previous animal studies of cardiovascular adaptations offer evidence that prolonged microgravity remodels walls of blood vessels, which in turn, is important for deconditioning of the cardiovascular system and other functions of the body. Over the past 10 years, our studies have documented that treadmill exercise within lower body negative pressure counteracts most physiologic decrements with bed rest in both women and men. Future studies should improve hardware and protocols to protect crew members during prolonged missions. Finally, it is proposed that transcapillary fluid shifts in microgravity may be related to the loss of tissue weight and external compression of blood vessels.
Collapse
Affiliation(s)
- Alan R Hargens
- Department of Orthopaedic Surgery, University of California, UCSD Medical Center, San Diego, 92103-8894, United States.
| | | |
Collapse
|