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Watanabe K, Koch Esteves N, Gibson OR, Akiyama K, Watanabe S, González-Alonso J. Heat-related changes in the velocity and kinetic energy of flowing blood influence the human heart's output during hyperthermia. J Physiol 2024; 602:2227-2251. [PMID: 38690610 DOI: 10.1113/jp285760] [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: 10/03/2023] [Accepted: 04/03/2024] [Indexed: 05/02/2024] Open
Abstract
Passive whole-body hyperthermia increases limb blood flow and cardiac output (Q ̇ $\dot Q$ ), but the interplay between peripheral and central thermo-haemodynamic mechanisms remains unclear. Here we tested the hypothesis that local hyperthermia-induced alterations in peripheral blood flow and blood kinetic energy modulate flow to the heart andQ ̇ $\dot Q$ . Body temperatures, regional (leg, arm, head) and systemic haemodynamics, and left ventricular (LV) volumes and functions were assessed in eight healthy males during: (1) 3 h control (normothermic condition); (2) 3 h of single-leg heating; (3) 3 h of two-leg heating; and (4) 2.5 h of whole-body heating. Leg, forearm, and extracranial blood flow increased in close association with local rises in temperature while brain perfusion remained unchanged. Increases in blood velocity with small to no changes in the conduit artery diameter underpinned the augmented limb and extracranial perfusion. In all heating conditions,Q ̇ $\dot Q$ increased in association with proportional elevations in systemic vascular conductance, related to enhanced blood flow, blood velocity, vascular conductance and kinetic energy in the limbs and head (all R2 ≥ 0.803; P < 0.001), but not in the brain. LV systolic (end-systolic elastance and twist) and diastolic functional profiles (untwisting rate), pulmonary ventilation and systemic aerobic metabolism were only altered in whole-body heating. These findings substantiate the idea that local hyperthermia-induced selective alterations in peripheral blood flow modulate the magnitude of flow to the heart andQ ̇ $\dot Q$ through changes in blood velocity and kinetic energy. Localised heat-activated events in the peripheral circulation therefore affect the human heart's output. KEY POINTS: Local and whole-body hyperthermia increases limb and systemic perfusion, but the underlying peripheral and central heat-sensitive mechanisms are not fully established. Here we investigated the regional (leg, arm and head) and systemic haemodynamics (cardiac output:Q ̇ $\dot Q$ ) during passive single-leg, two-leg and whole-body hyperthermia to determine the contribution of peripheral and central thermosensitive factors in the control of human circulation. Single-leg, two-leg, and whole-body hyperthermia induced graded increases in leg blood flow andQ ̇ $\dot Q$ . Brain blood flow, however, remained unchanged in all conditions. Ventilation, extracranial blood flow and cardiac systolic and diastolic functions only increased during whole-body hyperthermia. The augmentedQ ̇ $\dot Q$ with hyperthermia was tightly related to increased limb and head blood velocity, flow and kinetic energy. The findings indicate that local thermosensitive mechanisms modulate regional blood velocity, flow and kinetic energy, thereby controlling the magnitude of flow to the heart and thus the coupling of peripheral and central circulation during hyperthermia.
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Affiliation(s)
- Kazuhito Watanabe
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge, UK
- Faculty of Education and Human Studies, Akita University, Akita, Japan
| | - Nuno Koch Esteves
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge, UK
- Research Centre, University College of Osteopathy, London, UK
| | - Oliver R Gibson
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge, UK
- Centre for Physical Activity in Health and Disease, Brunel University London, Uxbridge, UK
| | - Koichi Akiyama
- Department of Anesthesiology, Kindai University Hospital, Osaka, Japan
| | - Sumie Watanabe
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge, UK
- Faculty of Education and Human Studies, Akita University, Akita, Japan
| | - José González-Alonso
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge, UK
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A century of exercise physiology: key concepts on coupling respiratory oxygen flow to muscle energy demand during exercise. Eur J Appl Physiol 2022; 122:1317-1365. [PMID: 35217911 PMCID: PMC9132876 DOI: 10.1007/s00421-022-04901-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 01/25/2022] [Indexed: 12/26/2022]
Abstract
After a short historical account, and a discussion of Hill and Meyerhof’s theory of the energetics of muscular exercise, we analyse steady-state rest and exercise as the condition wherein coupling of respiration to metabolism is most perfect. The quantitative relationships show that the homeostatic equilibrium, centred around arterial pH of 7.4 and arterial carbon dioxide partial pressure of 40 mmHg, is attained when the ratio of alveolar ventilation to carbon dioxide flow (\documentclass[12pt]{minimal}
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\begin{document}$${\dot{V}}_{A}/{\dot{V}}_{R}{CO}_{2}$$\end{document}V˙A/V˙RCO2) is − 21.6. Several combinations, exploited during exercise, of pertinent respiratory variables are compatible with this equilibrium, allowing adjustment of oxygen flow to oxygen demand without its alteration. During exercise transients, the balance is broken, but the coupling of respiration to metabolism is preserved when, as during moderate exercise, the respiratory system responds faster than the metabolic pathways. At higher exercise intensities, early blood lactate accumulation suggests that the coupling of respiration to metabolism is transiently broken, to be re-established when, at steady state, blood lactate stabilizes at higher levels than resting. In the severe exercise domain, coupling cannot be re-established, so that anaerobic lactic metabolism also contributes to sustain energy demand, lactate concentration goes up and arterial pH falls continuously. The \documentclass[12pt]{minimal}
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\begin{document}$${\dot{V}}_{A}/{\dot{V}}_{R}{CO}_{2}$$\end{document}V˙A/V˙RCO2 decreases below − 21.6, because of ensuing hyperventilation, while lactate keeps being accumulated, so that exercise is rapidly interrupted. The most extreme rupture of the homeostatic equilibrium occurs during breath-holding, because oxygen flow from ambient air to mitochondria is interrupted. No coupling at all is possible between respiration and metabolism in this case.
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Association of electrographic left ventricular hypertrophy with incident hypertension among the Tokyo 1964 Olympic athletes: a 50-year follow-up study. SPORT SCIENCES FOR HEALTH 2021. [DOI: 10.1007/s11332-021-00836-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sex differences in blood pressure regulation during the isometric exercise under heated environment. Blood Press Monit 2021; 27:55-62. [PMID: 34569989 DOI: 10.1097/mbp.0000000000000566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In the absence of heat stress, females increase blood pressure (BP) during isometric handgrip exercise due to cardiac output more than total peripheral resistance (TPR) compared to men. Although heat stress seems to blunt BP responses at rest and during handgrip, possible sex differences remained unknown. We hypothesized that BP responses during handgrip under a heated environment (HOT) will be different between men and women. Eight healthy men (29 ± 6 years) and eight women (26 ± 4 years) participated in this study. The experimental protocol was separated into two environmental conditions: HOT (~ 36 °C) and thermoneutral (TC; ~ 24 °C). In both conditions, participants rested for 30 min and performed the handgrip for 3 min. BP, heart rate (HR) stroke volume and cardiac output were continuously recorded, and TPR was calculated (TPR = mean blood pressure (MBP)/cardiac output). HOT reduced BP and TPR at baseline and during handgrip in females as compared to TC, while males showed similar responses in both thermal conditions. HR was higher under HOT in both groups. Cardiac output and stroke volume were not different under HOT compared to TC for females. In males, cardiac output increased at the last minute of handgrip under HOT through augmented HR, because stroke volume was unchanged. In conclusion, the main effect of HOT was to shift downwards BP and total peripheral resistance at rest and during isometric exercise in females. In males, the combination of handgrip and HOT increased cardiac output by augmented HR, whereas BP presented similar responses between thermal conditions during handgrip.
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Stens NA, Hisdal J, Bakke EF, Kaur N, Sharma A, Stranden E, Thijssen DHJ, Høiseth LØ. Factors mediating the pressor response to isometric muscle contraction: An experimental study in healthy volunteers during lower body negative pressure. PLoS One 2020; 15:e0243627. [PMID: 33296410 PMCID: PMC7725372 DOI: 10.1371/journal.pone.0243627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/24/2020] [Indexed: 12/20/2022] Open
Abstract
Whilst both cardiac output (CO) and total peripheral resistance (TPR) determine mean arterial blood pressure (MAP), their relative importance in the pressor response to isometric exercise remains unclear. This study aimed to elucidate the relative importance of these two different factors by examining pressor responses during cardiopulmonary unloading leading to step-wise reductions in CO. Hemodynamics were investigated in 11 healthy individuals before, during and after two-minute isometric exercise during lower body negative pressure (LBNP; -20mmHg and -40mmHg). The blood pressure response to isometric exercise was similar during normal and reduced preload, despite a step-wise reduction in CO during LBNP (-20mmHg and -40mmHg). During -20mmHg LBNP, the decreased stroke volume, and consequently CO, was counteracted by an increased TPR, while heart rate (HR) was unaffected. HR was increased during -40 mmHg LBNP, although insufficient to maintain CO; the drop in CO was perfectly compensated by an increased TPR to maintain MAP. Likewise, transient application of LBNP (-20mmHg and -40mmHg) resulted in a short transient drop in MAP, caused by a decrease in CO, which was compensated by an increase in TPR. This study suggests that, in case of reductions of CO, changes in TPR are primarily responsible for maintaining the pressor response during isometric exercise. This highlights the relative importance of TPR compared to CO in mediating the pressor response during isometric exercise.
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Affiliation(s)
- Niels A. Stens
- Department of Physiology, Research Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
| | - Jonny Hisdal
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Espen F. Bakke
- Institute of Aviation Medicine, Norwegian Armed Forces Medical Service, Oslo, Norway
| | - Narinder Kaur
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
- Dermatology Center Telemark, Porsgrunn, Norway
| | - Archana Sharma
- Department of Endocrinology, Oslo University Hospital, Oslo, Norway
- Department of Anesthesiology, Oslo University Hospital, Oslo, Norway
| | - Einar Stranden
- Department of Vascular Surgery, Division of Cardiovascular and Pulmonary Diseases, Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway
| | - Dick H. J. Thijssen
- Department of Physiology, Research Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Lars Øivind Høiseth
- Department of Anesthesiology, Oslo University Hospital, Oslo, Norway
- * E-mail:
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Watanabe K, Stöhr EJ, Akiyama K, Watanabe S, González‐Alonso J. Dehydration reduces stroke volume and cardiac output during exercise because of impaired cardiac filling and venous return, not left ventricular function. Physiol Rep 2020; 8:e14433. [PMID: 32538549 PMCID: PMC7294577 DOI: 10.14814/phy2.14433] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 04/12/2020] [Indexed: 12/17/2022] Open
Abstract
Dehydration accrued during intense prolonged whole-body exercise in the heat compromises peripheral blood flow and cardiac output ( Q ˙ ). A markedly reduced stroke volume (SV) is a key feature of the dehydration-induced cardiovascular strain, but whether the lower output of the heart is mediated by peripheral or cardiac factors remains unknown. Therefore, we repeatedly quantified left ventricular (LV) volumes, LV mechanics (LV twist, a marker of systolic muscle function, and LV untwisting rate, an independent marker of LV muscle relaxation), left intra-ventricular pressure gradients, blood volume and peripheral blood flow during 2 hr of cycling in the heat with and without dehydration (DEH: 4.0 ± 0.2% body mass loss and EUH: euhydration control, respectively) in eight participants (three females and five males). While brachial and carotid blood flow, blood volume, SV, LV end-diastolic volume (LVEDV), cardiac filling time, systemic vascular conductance and Q ˙ were reduced in DEH compared to EUH after 2 hr, LV twist and untwisting rate tended to be higher (p = .09 and .06, respectively) and intra-ventricular pressure gradients were not different between the two conditions (p = .22). Furthermore, LVEDV in DEH correlated strongly with blood volume (r = .995, p < .01), head and forearms beat volume (r = .98, p < .05), and diastolic LV filling time (r = .98, p < .05). These findings suggest that the decline in SV underpinning the blunted Q ˙ with exercise-induced dehydration is caused by compromised LV filling and venous return, but not intrinsic systolic or diastolic LV function.
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Affiliation(s)
- Kazuhito Watanabe
- Centre for Human Performance, Exercise and RehabilitationBrunel University LondonUxbridgeUK
- Faculty of Education and Human StudiesAkita UniversityAkitaJapan
| | - Eric J. Stöhr
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
- Department of MedicineDivision of CardiologyColumbia University Irving Medical CenterNew York CityNYUSA
| | - Koichi Akiyama
- Department of AnesthesiologyYodogawa Christian HospitalOsakaJapan
| | - Sumie Watanabe
- Centre for Human Performance, Exercise and RehabilitationBrunel University LondonUxbridgeUK
| | - José González‐Alonso
- Centre for Human Performance, Exercise and RehabilitationBrunel University LondonUxbridgeUK
- Division of Sport, Health and Exercise SciencesDepartment of Life SciencesBrunel University LondonUxbridgeUK
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Fagoni N, Bruseghini P, Adami A, Capelli C, Lador F, Moia C, Tam E, Bringard A, Ferretti G. Effect of Lower Body Negative Pressure on Phase I Cardiovascular Responses at Exercise Onset. Int J Sports Med 2020; 41:209-218. [PMID: 31958874 PMCID: PMC7286127 DOI: 10.1055/a-1028-7496] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We hypothesised that vagal withdrawal and increased venous return interact in determining the
rapid cardiac output (CO) response (phase I) at exercise onset. We used lower body negative
pressure (LBNP) to increase blood distribution to the heart by muscle pump action and reduce
resting vagal activity. We expected a larger increase in stroke volume (SV) and smaller for
heart rate (HR) at progressively stronger LBNP levels, therefore CO response would remain
unchanged. To this aim ten young, healthy males performed a 50 W exercise in supine
position at 0 (Control), −15, −30 and −45 mmHg LBNP exposure.
On single beat basis, we measured HR, SV, and CO. Oxygen uptake was measured breath-by-breath.
Phase I response amplitudes were obtained applying an exponential model. LBNP increased SV
response amplitude threefold from Control to −45 mmHg. HR response amplitude
tended to decrease and prevented changes in CO response. The rapid response of CO explained
that of oxygen uptake. The rapid SV kinetics at exercise onset is compatible with an increased
venous return, whereas the vagal withdrawal conjecture cannot be dismissed for HR. The rapid CO
response may indeed be the result of two independent yet parallel mechanisms, one acting on SV,
the other on HR.
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Affiliation(s)
- Nazzareno Fagoni
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Paolo Bruseghini
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Alessandra Adami
- Department of Kinesiology, University of Rhode Island, United States
| | - Carlo Capelli
- Department of Physical Performances, Norwegian School of Sport Sciences, Oslo, Norway
| | - Frederic Lador
- Division de Pneumologie, Département des Spécialités de Médecine, Hôpitaux Universitaires de Genève, Geneva, Switzerland
| | - Christian Moia
- Département des Neurosciences Fondamentales, Université de Genève Centre Médical Universitaire, Geneve, Switzerland
| | - Enrico Tam
- Dipartimento di Scienze Neurologiche e della Visione, University of Verona, Verona, Italy
| | | | - Guido Ferretti
- Département des Neurosciences Fondamentales, Université de Genève Centre Médical Universitaire, Geneve, Switzerland
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Samora M, Incognito AV, Vianna LC. Sex differences in blood pressure regulation during ischemic isometric exercise: the role of the β-adrenergic receptors. J Appl Physiol (1985) 2019; 127:408-414. [PMID: 31219771 DOI: 10.1152/japplphysiol.00270.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We sought to investigate whether the β-adrenergic receptors play a pivotal role in sex-related differences in arterial blood pressure (BP) regulation during isometric exercise. Sixteen volunteers (8 women) performed 2 min of ischemic isometric handgrip exercise (IHE) and 2 min of postexercise circulatory occlusion (PECO). Heart rate (HR) and beat-to-beat arterial BP were continuously measured. Beat-to-beat estimates of stroke volume (ModelFlow) were obtained and matched with HR to calculate cardiac output (Q̇) and total peripheral resistance (TPR). Two trials were randomly conducted between placebo and nonselective β-adrenergic blockade (40 mg propranolol). Under the placebo condition, the magnitude of the BP response in IHE was lower in women compared with men. During PECO, the BP remained elevated and the sex differences persisted. The β-blockade attenuated the BP response during IHE in men (∆57 ± 4 vs. ∆45 ± 7 mmHg, P = 0.025) due to a reduction in Q̇ (∆3.7 ± 0.5 vs. ∆1.8 ± 0.2 L/min, P = 0.012) while TPR was not affected. In women, however, the BP response during IHE was unchanged (∆27 ± 3 vs. ∆28 ± 3 mmHg, P = 0.889), despite attenuated Q̇ (∆2.7 ± 0.4 vs. ∆1.3 ± 0.2 L/min, P = 0.012). These responses were mediated by a robust increase in TPR under β-blockade (∆-0.2 ± 0.4 vs. ∆2.2 ± 0.7 mmHg·L-1·min, P = 0.012). These findings demonstrate that the sex differences in arterial BP regulation during ischemic IHE are mediated by β-adrenergic receptors.NEW & NOTEWORTHY We found that the blood pressure response during isometric exercise in women is mediated by increases in cardiac output, whereas in men it is mediated by increases in both cardiac output and total peripheral resistance. In addition, women showed a robust increase in total peripheral resistance under β-blockade during isometric exercise and muscle metaboreflex activation. These findings demonstrate that sex differences in blood pressure regulation during isometric exercise are mediated by β-adrenergic receptors.
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Affiliation(s)
- Milena Samora
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasilia, Distrito Federal, Brazil
| | - Anthony V Incognito
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasilia, Distrito Federal, Brazil.,Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Lauro C Vianna
- NeuroV̇ASQ̇-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasilia, Distrito Federal, Brazil
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Forouzan O, Dinges E, Runo JR, Keevil JG, Eickhoff JC, Francois C, Chesler NC. Exercise-Induced Changes in Pulmonary Artery Stiffness in Pulmonary Hypertension. Front Physiol 2019; 10:269. [PMID: 31001123 PMCID: PMC6454859 DOI: 10.3389/fphys.2019.00269] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 02/28/2019] [Indexed: 11/23/2022] Open
Abstract
Background: Pulmonary hypertension causes pulmonary artery (PA) stiffening, which overloads the right ventricle (RV). Since symptoms of pulmonary hypertension (PH) are exacerbated by exercise, exercise-induced PA stiffening is relevant to cardiopulmonary status. Here, we sought to demonstrate the feasibility of using magnetic resonance imaging (MRI) for non-invasive assessment of exercise-induced changes in PA stiffness in patients with PH. Methods: MRI was performed on 7 PH patients and 8 age-matched control subjects at rest and during exercise stress. Main pulmonary artery (MPA) relative area change (RAC) and pulse wave velocity (PWV) were measured from 2D-PC images. Invasive right heart catheterization (RHC) was performed on 5 of the PH patients in conjunction with exercise stress to measure MPA pressures and stiffness index (β). Results: Heart rate and cardiac index (CI) were significantly increased with exercise in both groups. In controls, RAC decreased from 0.27 ± 0.05 at rest to 0.22 ± 0.06 with exercise (P < 0.05); a modest increase in PWV was not significant (P = 0.06). In PH patients, RAC decreased from 0.15 ± 0.02 to 0.11 ± 0.01 (P < 0.05) and PWV and β increased from 3.9 ± 0.54 m/s and 1.86 ± 0.12 at rest to 5.75 ± 0.70 m/s and 3.25 ± 0.26 with exercise (P < 0.05 for both), respectively. These results confirm increased MPA stiffness with exercise stress in both groups and the non-invasive metrics of MPA stiffness correlated well with β. Finally, as assessed by PWV but not RAC, PA stiffness of PH patients increased more than that of controls for comparable levels of moderate exercise. Conclusion: These results demonstrate the feasibility of using MRI for non-invasive assessment of exercise-induced changes in MPA stiffness in a small, heterogeneous group of PH patients in a research context. Similar measurements in a larger cohort are required to investigate differences between PWV and RAC for estimation of MPA stiffness.
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Affiliation(s)
- Omid Forouzan
- College of Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Eric Dinges
- College of Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - James R Runo
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Jonathan G Keevil
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Jens C Eickhoff
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Christopher Francois
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Naomi C Chesler
- College of Engineering, University of Wisconsin-Madison, Madison, WI, United States.,School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
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Abstract
PURPOSE To determine whether heart-rate variability (HRV) was correlated with other training-load and training-tolerance markers for monitoring the effect of a training session on elite synchronized swimmers. METHODS The authors recorded the resting HRV of 12 elite swimmers (mean age = 21.5 [3.5] y) 3 times over 1 wk with a cadence of 48 h prior to the 2015 World Swimming Championships. They continuously monitored heart rate and obtained salivary cortisol (SC) samples before and after the last training session of the week. The authors measured capillary blood lactate (La) 2, 4, and 8 min after the last training session and monitored recovery HRV. They assessed rating of perceived exertion (RPE) over the entire session and tested the association between the highest La concentration (Lapeak), SC, and RPE and relative changes (Δ%) in the natural logarithm of the root-mean-square successive difference of intervals (LnRMSSD). The authors also calculated the smallest worthwhile change of the averaged pre and post LnRMSSD measurements. RESULTS There were periods of pronounced bradycardia (60.5 [16.7] beats/min) during training exercises corresponding to apneic exercise. The magnitude-based inferences showed nonclinically meaningful changes of LnRMSSD. Lapeak (6.8 [2.7] mmol/L) correlated positively with Δ%LnRMSSD and Δ%SC (r = .89, P = .001 and r = .61, P = .04, respectively). CONCLUSIONS There was no change in LnRMSSD and Lapeak, Δ%SC, and RPE indicated reduced sympathetic activation and positive adaptation to the stress imposed by the session. Isolated HRV assessment may reveal a controversial interpretation of autonomic nervous system status or the training tolerance in elite synchronized swimming athletes due to the influence of the diving response.
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Skytioti M, Søvik S, Elstad M. Dynamic cerebral autoregulation is preserved during isometric handgrip and head-down tilt in healthy volunteers. Physiol Rep 2018; 6:e13656. [PMID: 29595918 PMCID: PMC5875546 DOI: 10.14814/phy2.13656] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 02/20/2018] [Accepted: 02/26/2018] [Indexed: 12/29/2022] Open
Abstract
In healthy humans, cerebral blood flow (CBF) is autoregulated against changes in arterial blood pressure. Spontaneous fluctuations in mean arterial pressure (MAP) and CBF can be used to assess cerebral autoregulation. We hypothesized that dynamic cerebral autoregulation is affected by changes in autonomic activity, MAP, and cardiac output (CO) induced by handgrip (HG), head‐down tilt (HDT), and their combination. In thirteen healthy volunteers, we recorded blood velocity by ultrasound in the internal carotid artery (ICA), HR, MAP and CO‐estimates from continuous finger blood pressure, and end‐tidal CO2. Instantaneous ICA beat volume (ICABV, mL) and ICA blood flow (ICABF, mL/min) were calculated. Wavelet synchronization index γ (0–1) was calculated for the pairs: MAP–ICABF, CO–ICABF and HR–ICABV in the low (0.05–0.15 Hz; LF) and high (0.15–0.4 Hz; HF) frequency bands. ICABF did not change between experimental states. MAP and CO were increased during HG (+16% and +15%, respectively, P < 0.001) and during HDT + HG (+12% and +23%, respectively, P < 0.001). In the LF interval, median γ for the MAP–ICABF pair (baseline: 0.23 [0.12–0.28]) and the CO–ICABF pair (baseline: 0.22 [0.15–0.28]) did not change with HG, HDT, or their combination. High γ was observed for the HR–ICABV pair at the respiratory frequency, the oscillations in these variables being in inverse phase. The unaltered ICABF and the low synchronization between MAP and ICABF in the LF interval suggest intact dynamic cerebral autoregulation during HG, HDT, and their combination.
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Affiliation(s)
- Maria Skytioti
- Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Signe Søvik
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,Department of Anaesthesia and Intensive Care, Akershus University Hospital, Lørenskog, Norway
| | - Maja Elstad
- Division of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Sanna I, Pinna V, Milia R, Roberto S, Olla S, Mulliri G, Crisafulli A. Hemodynamic Responses during Enduro-Motorcycling Performance. Front Physiol 2018; 8:1062. [PMID: 29311986 PMCID: PMC5736362 DOI: 10.3389/fphys.2017.01062] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/04/2017] [Indexed: 12/02/2022] Open
Abstract
Much of the information available in the literature on physiological responses during Enduro motorcycling is related to heart rate (HR) and blood lactate (BLa). The aim of this work was to investigate the hemodynamic changes that occur during a 10-min session of Enduro motorcycling. Fifteen skilled riders were enrolled on the study and all participants underwent an Enduro-motorcycling session on a standard track. Hemodynamics were assessed using a miniaturized impedance cardiograph. Results show that HR significantly increased from 96.5 ± 12.8 bpm at rest to 153.1 ± 17.7 bpm during riding, while stroke volume (SV) increased from 53.5 ± 14.1 to 72.2 ± 22.1 ml and cardiac output (CO) from 5.0 ± 1.1 to 10.9 ± 3.0 L·min−1. Moreover, ventricular emptying rate (VER) increased from 192.9 ± 43.0 to 324.1 ± 83.6 ml·s1 and ventricular filling rate (VFR) from 141.1 ± 160.5 to 849 ± 309 ml·s−1. Taken together, these data suggest that Enduro motorcycling induces substantial cardiovascular activation, not only in terms of chronotropism but also in terms of cardiac performance and pre-load, thereby increasing SV and CO. Finally, it is likely that sympathetic-mediated venous constriction occurred. This in turn improved VFR and recruited the Frank-Starling mechanism and inotropic reserve. It was concluded that Enduro motorcycling is a challenging activity for the cardiovascular apparatus.
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Affiliation(s)
- Irene Sanna
- Department of Medical Science and Public Health, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Virginia Pinna
- Department of Medical Science and Public Health, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Raffaele Milia
- Department of Medical Science and Public Health, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Silvana Roberto
- Department of Medical Science and Public Health, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Sergio Olla
- Department of Medical Science and Public Health, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Gabriele Mulliri
- Department of Medical Science and Public Health, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
| | - Antonio Crisafulli
- Department of Medical Science and Public Health, Sports Physiology Laboratory, University of Cagliari, Cagliari, Italy
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Verma AK, Xu D, Garg A, Cote AT, Goswami N, Blaber AP, Tavakolian K. Non-linear Heart Rate and Blood Pressure Interaction in Response to Lower-Body Negative Pressure. Front Physiol 2017; 8:767. [PMID: 29114227 PMCID: PMC5660688 DOI: 10.3389/fphys.2017.00767] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 09/20/2017] [Indexed: 12/14/2022] Open
Abstract
Early detection of hemorrhage remains an open problem. In this regard, blood pressure has been an ineffective measure of blood loss due to numerous compensatory mechanisms sustaining arterial blood pressure homeostasis. Here, we investigate the feasibility of causality detection in the heart rate and blood pressure interaction, a closed-loop control system, for early detection of hemorrhage. The hemorrhage was simulated via graded lower-body negative pressure (LBNP) from 0 to -40 mmHg. The research hypothesis was that a significant elevation of causal control in the direction of blood pressure to heart rate (i.e., baroreflex response) is an early indicator of central hypovolemia. Five minutes of continuous blood pressure and electrocardiogram (ECG) signals were acquired simultaneously from young, healthy participants (27 ± 1 years, N = 27) during each LBNP stage, from which heart rate (represented by RR interval), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were derived. The heart rate and blood pressure causal interaction (RR↔SBP and RR↔MAP) was studied during the last 3 min of each LBNP stage. At supine rest, the non-baroreflex arm (RR→SBP and RR→MAP) showed a significantly (p < 0.001) higher causal drive toward blood pressure regulation compared to the baroreflex arm (SBP→RR and MAP→RR). In response to moderate category hemorrhage (-30 mmHg LBNP), no change was observed in the traditional marker of blood loss i.e., pulse pressure (p = 0.10) along with the RR→SBP (p = 0.76), RR→MAP (p = 0.60), and SBP→RR (p = 0.07) causality compared to the resting stage. Contrarily, a significant elevation in the MAP→RR (p = 0.004) causality was observed. In accordance with our hypothesis, the outcomes of the research underscored the potential of compensatory baroreflex arm (MAP→RR) of the heart rate and blood pressure interaction toward differentiating a simulated moderate category hemorrhage from the resting stage. Therefore, monitoring baroreflex causality can have a clinical utility in making triage decisions to impede hemorrhage progression.
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Affiliation(s)
- Ajay K Verma
- Department of Electrical Engineering, University of North Dakota, Grand Forks, ND, United States
| | - Da Xu
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Amanmeet Garg
- Department of Engineering Science, Simon Fraser University, Burnaby, BC, Canada
| | - Anita T Cote
- School of Human Kinetics, Trinity Western University, Langley, BC, Canada
| | - Nandu Goswami
- Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Andrew P Blaber
- Department of Electrical Engineering, University of North Dakota, Grand Forks, ND, United States.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Kouhyar Tavakolian
- Department of Electrical Engineering, University of North Dakota, Grand Forks, ND, United States.,Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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Black JM, Stöhr EJ, Stone K, Pugh CJA, Stembridge M, Shave R, Esformes JI. The effect of an acute bout of resistance exercise on carotid artery strain and strain rate. Physiol Rep 2017; 4:4/17/e12959. [PMID: 27624687 PMCID: PMC5027362 DOI: 10.14814/phy2.12959] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 08/06/2016] [Indexed: 01/10/2023] Open
Abstract
Arterial wall mechanics likely play an integral role in arterial responses to acute physiological stress. Therefore, this study aimed to determine the impact of low and moderate intensity double‐leg press exercise on common carotid artery (CCA) wall mechanics using 2D vascular strain imaging. Short‐axis CCA ultrasound images were collected in 15 healthy men (age: 21 ± 3 years; stature: 176.5 ± 6.2 cm; body mass; 80.6 ± 15.3 kg) before, during, and immediately after short‐duration isometric double‐leg press exercise at 30% and 60% of participants' one‐repetition maximum (1RM: 317 ± 72 kg). Images were analyzed for peak circumferential strain (PCS), peak systolic and diastolic strain rate (S‐SR and D‐SR), and arterial diameter. Heart rate (HR), systolic and diastolic blood pressure (SBP and DBP) were simultaneously assessed and arterial stiffness indices were calculated post hoc. A two‐way repeated measures ANOVA revealed that during isometric contraction, PCS and S‐SR decreased significantly (P < 0.01) before increasing significantly above resting levels post exercise (P < 0.05 and P < 0.01, respectively). Conversely, D‐SR was unaltered throughout the protocol (P = 0.25). No significant differences were observed between the 30% and 60% 1RM trials. Multiple regression analysis highlighted that HR, BP, and arterial diameter did not fully explain the total variance in PCS, S‐SR, and D‐SR. Acute double‐leg press exercise is therefore associated with similar transient changes in CCA wall mechanics at low and moderate intensities. CCA wall mechanics likely provide additional insight into localized intrinsic vascular wall properties beyond current measures of arterial stiffness.
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Affiliation(s)
- Jane M Black
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Eric J Stöhr
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Keeron Stone
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Christopher J A Pugh
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Mike Stembridge
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Rob Shave
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Joseph I Esformes
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, United Kingdom Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, United Kingdom
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15
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Bringard A, Adami A, Fagoni N, Fontolliet T, Lador F, Moia C, Tam E, Ferretti G. Dynamics of the RR-interval versus blood pressure relationship at exercise onset in humans. Eur J Appl Physiol 2017; 117:619-630. [PMID: 28238048 DOI: 10.1007/s00421-017-3564-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE The dynamics of the postulated phenomenon of exercise baroreflex resetting is poorly understood, but can be investigated using closed-loop procedures. To shed light on some mechanisms and temporal relationships participating in the resetting process, we studied the time course of the relationship between the R-R interval (RRi) and arterial pressure with a closed-loop approach. METHODS On ten young volunteers at rest and during light exercise in supine and upright position, we continuously determined, on single-beat basis, RRi (electrocardiography), and arterial pressure (non-invasive finger pressure cuff). From pulse pressure profiles, we determined cardiac output (CO) by Modelflow, computed mean arterial pressure (MAP), and calculated total peripheral resistance (TPR). RESULTS At exercise start, RRi was lower than in quiet rest. As exercise started, MAP fell to a minimum (MAPm) of 72.8 ± 9.6 mmHg upright and 73.9 ± 6.2 supine, while RRi dropped. The initial RRi versus MAP relationship was linear, with flatter slope than resting baroreflex sensitivity, in both postures. TPR fell and CO increased. After MAPm, RRi and MAP varied in opposite direction toward exercise steady state, with further CO increase. CONCLUSION These results suggest that, initially, the MAP fall was corrected by a RRi reduction along a baroreflex curve, with lower sensitivity than at rest, but eventually in the same pressure range as at rest. After attainment of MAPm, a second phase started, where the postulated baroreflex resetting might have occurred. In conclusion, the change in baroreflex sensitivity and the resetting process are distinct phenomena, under different control systems.
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Affiliation(s)
- Aurélien Bringard
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Alessandra Adami
- Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland.,Division of Respiratory and Critical Care Physiology and Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 W Carson St, Torrance, CA, 90502, USA
| | - Nazzareno Fagoni
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy
| | - Timothée Fontolliet
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Frédéric Lador
- Service de Pneumologie, Programme Hypertension Pulmonaire, Département des Spécialités de Médecine, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève, Switzerland
| | - Christian Moia
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Enrico Tam
- Dipartimento di Scienze Neurologiche, Biomediche e del Movimento, Università di Verona, Via Felice Casorati 43, 37131, Verona, Italy
| | - Guido Ferretti
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland. .,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland. .,Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy.
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Moon HW, Shin SH, Lee CH, Park HY, Sunoo S, Nam SS. Effects of various acute hypoxic conditions on the hemorheological response during exercise and recovery1. Clin Hemorheol Microcirc 2017; 63:451-460. [PMID: 27447423 DOI: 10.3233/ch-16163] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Even though exercise hemorheology at hypoxic condition has been considered as a good tool to understand clinical hemorheology, there have been limited studies reported. Previous researches showed that hemorheological variables are closely correlated with oxygen delivery capacity during exercise. The present study investigated hypoxic responses including RBC deformability and aggregation, metabolic parameters and complete blood cell counts at various hypoxic conditions during cycling exercise and recovery. Eleven Korean healthy male subjects performed submaximal bike exercise at sea level (20.9% O2) and under various hypoxic conditions (16.5% O2, 14.5% O2, 12.8% O2, and 11.2% O2) in a random order. The submaximal bike exercise intensity of the subjects was 70% maximum heart rate at sea level. All variables were measured at rest, during exercise and recovery 30-minute, respectively. As oxygen partial pressure decreased, arterial blood oxygen saturation decreased but oxygen uptake did not change much. Heart rate and lactate concentration during exercise increased when oxygen partial pressure is less than or equal to 14.5% O2 condition. Red blood cell (RBC) counts, hemoglobin counts, and hematocrit level were not apparently altered with hypoxic conditions. RBC deformability showed significant alterations at 11.2% O2 conditions compared with other hypoxic conditions during exercise or recovery, except at 10 minutes recovery. However, decreases in oxygen partial pressure did not affect red blood cell aggregation. Therefore, we conclude that alterations in RBC deformability may reduce aerobic capabilities at hypoxic condition.
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Affiliation(s)
- Hwang-Woon Moon
- Department of Sports and Outdoors, Eulji University, Seongnam, Korea
| | - Se-Hyun Shin
- School of Mechanical Engineering, Korea University, Seoul, Korea
| | - Chul-Hyun Lee
- Department of Sports Medicine, Kyunghee University, Yongin, Korea
| | - Hun-Young Park
- Department of Physical Activity and Performance Institute, Kunkuk University, Seoul, Korea
| | - Sub Sunoo
- Department of Sports Medicine, Kyunghee University, Yongin, Korea
| | - Sang-Seok Nam
- Department of Sports Medicine, Kyunghee University, Yongin, Korea
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17
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Cardiac stroke volume variability measured non-invasively by three methods for detection of central hypovolemia in healthy humans. Eur J Appl Physiol 2016; 116:2187-2196. [DOI: 10.1007/s00421-016-3471-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 09/05/2016] [Indexed: 10/21/2022]
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18
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Moon HW, Sunoo S, Park HY, Lee DJ, Nam SS. Effects of various acute hypoxic conditions on metabolic parameters and cardiac function during exercise and recovery. SPRINGERPLUS 2016; 5:1294. [PMID: 27547668 PMCID: PMC4977266 DOI: 10.1186/s40064-016-2952-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/29/2016] [Indexed: 01/08/2023]
Abstract
Purpose Evaluation of metabolic parameters and cardiac function is important to determine the decrease in aerobic exercise capacity under hypoxic conditions. However, the variations in metabolic parameters and cardiac function and the reasons for the decrease in aerobic exercise capacity under hypoxic conditions have not been clearly explained. The purpose of this study was to compare the responses between sea level and various acute normobaric hypoxic conditions on metabolic parameters and cardiac function during exercise and recovery in order to evaluate aerobic exercise capacity. Methods Ten healthy male participants (21.3 ± 3.06 y) performed submaximal bicycle exercise (116.7 ± 20.1 W and 60 rpm) at sea level (20.9 % O2) and under various normobaric hypoxic conditions (16.5 % O2, 14.5 % O2, 12.8 % O2, and 11.2 % O2) in a random order. Metabolic parameters (arterial oxygen saturation; SPO2, oxygen consumption; VO2, blood lactate level) and cardiac function (heart rate; HR, stroke volume; SV, end-systolic volume; ESV, end-diastolic volume; EDV, ejection fraction; EF, cardiac output; CO) were measured at rest, during exercise (30 min), and recovery (30 min). We compared the responses on metabolic parameters and cardiac function between the different oxygen partial pressure conditions during exercise and recovery. Results The various acute normobaric hypoxic conditions did not affect VO2 and SV during exercise and recovery. SPO2 decreased (p < .05) and blood lactate level increased (p < .05) as the oxygen partial pressure decreased. HR, EF, CO increased (p < .05) and EDV, ESV decreased (p < .05) at oxygen partial pressures of 14.5 % O2 and below compared with 20.9 and 16.5 % O2 during exercise and recovery. Conclusion A decrease in the oxygen partial pressure to 14.5 % O2 and below might be associated with significant changes in metabolic parameters and cardiac function during exercise and recovery. These changes are an acute compensation response to reduced aerobic exercise capacity by decreased oxygen delivering and utilizing capacities under hypoxic conditions.
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Affiliation(s)
- Hwang-Woon Moon
- Department of Sports and Outdoors, Eulji University, Yangji-dong, Sujeong-gu, Seongnam-si, Gyeonggi-do 461-713 Republic of Korea
| | - Sub Sunoo
- Department of Sports Medicine, Kyunghee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104 Republic of Korea
| | - Hun-Young Park
- Performance Activity and Performance Institute, Konkuk University, Hwayang-dong, Gwangjin-gu, Seoul, 143-701 Republic of Korea
| | - Dong-Jun Lee
- Department of Physical Education, MyongJi University, Yongin Campus, Nam-dong, Cheoin-gu, Yongin-si, Gyeonggi-do 449-728 Republic of Korea
| | - Sang-Seok Nam
- Department of Sports Medicine, Kyunghee University, 1732, Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104 Republic of Korea
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Hemodynamic, Autonomic, Ventilatory, and Metabolic Alterations After Resistance Training in Patients With Coronary Artery Disease: A Randomized Controlled Trial. Am J Phys Med Rehabil 2016; 96:226-235. [PMID: 27386813 DOI: 10.1097/phm.0000000000000568] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE The aim of this work was to evaluate the hemodynamic, autonomic, and metabolic responses during resistance and dynamic exercise before and after an 8-week resistance training program using a low-intensity (30% of 1 repetitium maximum), high-repetition (3 sets of 20 repetitions) model, added to an aerobic training program, in a coronary artery disease cohort. DESIGN Twenty male subjects with coronary artery disease (61.1 ± 4.7 years) were randomly assigned to a combined training group (resistance + aerobic) or aerobic training group (AG). Heart rate, stroke volume, cardiac output, minute ventilation, blood lactate, and parasympathetic modulation indices of heart rate (square root of the mean squared differences of successive RR intervals [RMSSD] and dispersion of points perpendicular to the line of identity that provides information about the instantaneous beat-to-beat variability [SD1]) were obtained before and after an 8-week RT program while performing exercise on a cycle ergometer and a 45-degree leg press. RESULTS Resistance training resulted in an increase in maximal and submaximal load tolerance (P < 0.01), a decreased hemodynamic response (P < 0.01), and a reduction in blood lactate in the combined training group compared to the aerobic training group during the 45-degree leg press. During exercise on a cycle ergometer, there was a decreased hemodynamic response and increased minute ventilation (P < 0.01). The 8-week RT program resulted in greater parasympathetic tone (RMSSD and SD1) and an increase in the SDNN index during exercise on a cycle ergometer and 45-degree leg press (P < 0.05). CONCLUSIONS An 8-week resistance training program associated with aerobic training may attenuate hemodynamic stress, and modify metabolic and autonomic responses during resistance exercise. The training program also appeared to elicit beneficial cardiovascular and autonomic effects during exercise.
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Weippert M, Behrens M, Gonschorek R, Bruhn S, Behrens K. Muscular contraction mode differently affects autonomic control during heart rate matched exercise. Front Physiol 2015; 6:156. [PMID: 26042047 PMCID: PMC4436571 DOI: 10.3389/fphys.2015.00156] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 04/29/2015] [Indexed: 11/13/2022] Open
Abstract
The precise contributions of afferent feedback to cardiovascular and respiratory responses to exercise are still unclear. The aim of this crossover study was to assess whether and how autonomic cardiovascular and respiratory control differed in response to dynamic (DYN) and isometric contractions (ISO) at a similar, low heart rate (HR) level. Therefore, 22 healthy males (26.7 ± 3.6 yrs) performed two kinds of voluntary exercises at similar HR: ISO and DYN of the right quadriceps femoris muscle. Although HR was eqivalent (82 ± 8 bpm for DYN and ISO, respectively), rating of exertion, blood pressures, and rate pressure product were higher, whereas breathing frequency, minute ventilation, oxygen uptake and carbon dioxide output were significantly lower during ISO. Tidal volume, end-tidal partial pressures of O2 and CO2, respiratory exchange ratio and capillary blood lactate concentration were comparable between both contraction modes. Heart rate variability (HRV) indicators, SDNN, HF-Power and LF-Power, representing both vagal and sympathetic influences, were significantly higher during ISO. Sample entropy, a non-linear measure of HRV was also significantly affected by contraction mode. It can be concluded that, despite the same net effect on HR, the quality of cardiovascular control during low intensity exercise is significantly different between DYN and ISO. HRV analysis indicated a sympatho-vagal coactivation during ISO. Whether mechanoreceptor feedback alone, a change in central command, or the interaction of both mechanisms is the main contributor of the distinct autonomic responses to the different exercise modes remains to be elucidated.
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Affiliation(s)
- Matthias Weippert
- Institute of Sport Science, University of Rostock Rostock, Germany ; Institute of Exercise Physiology and Public Health Rostock, Germany
| | - Martin Behrens
- Institute of Sport Science, University of Rostock Rostock, Germany
| | - Ray Gonschorek
- Institute of Sport Science, University of Rostock Rostock, Germany
| | - Sven Bruhn
- Institute of Sport Science, University of Rostock Rostock, Germany
| | - Kristin Behrens
- Institute of Exercise Physiology and Public Health Rostock, Germany
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21
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Spruijt OA, de Man FS, Groepenhoff H, Oosterveer F, Westerhof N, Vonk-Noordegraaf A, Bogaard HJ. The Effects of Exercise on Right Ventricular Contractility and Right Ventricular–Arterial Coupling in Pulmonary Hypertension. Am J Respir Crit Care Med 2015; 191:1050-7. [DOI: 10.1164/rccm.201412-2271oc] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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22
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Choate JK, Denton KM, Evans RG, Hodgson Y. Using stimulation of the diving reflex in humans to teach integrative physiology. ADVANCES IN PHYSIOLOGY EDUCATION 2014; 38:355-365. [PMID: 25434020 DOI: 10.1152/advan.00125.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
During underwater submersion, the body responds by conserving O2 and prioritizing blood flow to the brain and heart. These physiological adjustments, which involve the nervous, cardiovascular, and respiratory systems, are known as the diving response and provide an ideal example of integrative physiology. The diving reflex can be stimulated in the practical laboratory setting using breath holding and facial immersion in water. Our undergraduate physiology students complete a laboratory class in which they investigate the effects of stimulating the diving reflex on cardiovascular variables, which are recorded and calculated with a Finapres finger cuff. These variables include heart rate, cardiac output, stroke volume, total peripheral resistance, and arterial pressures (mean, diastolic, and systolic). Components of the diving reflex are stimulated by 1) facial immersion in cold water (15°C), 2) breathing with a snorkel in cold water (15°C), 3) facial immersion in warm water (30°C), and 4) breath holding in air. Statistical analysis of the data generated for each of these four maneuvers allows the students to consider the factors that contribute to the diving response, such as the temperature of the water and the location of the sensory receptors that initiate the response. In addition to providing specific details about the equipment, protocols, and learning outcomes, this report describes how we assess this practical exercise and summarizes some common student misunderstandings of the essential physiological concepts underlying the diving response.
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Affiliation(s)
- Julia K Choate
- Department of Physiology, School of Biomedical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Kate M Denton
- Department of Physiology, School of Biomedical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Roger G Evans
- Department of Physiology, School of Biomedical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Yvonne Hodgson
- Department of Physiology, School of Biomedical Sciences, Monash University, Melbourne, Victoria, Australia
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23
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Sample Entropy and Traditional Measures of Heart Rate Dynamics Reveal Different Modes of Cardiovascular Control During Low Intensity Exercise. ENTROPY 2014. [DOI: 10.3390/e16115698] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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24
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Watanabe K, Ichinose M, Tahara R, Nishiyasu T. Individual differences in cardiac and vascular components of the pressor response to isometric handgrip exercise in humans. Am J Physiol Heart Circ Physiol 2014; 306:H251-60. [DOI: 10.1152/ajpheart.00699.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypotheses that, in humans, changes in cardiac output (CO) and total peripheral vascular resistance (TPR) occurring in response to isometric handgrip exercise vary considerably among individuals and that those individual differences are related to differences in muscle metaboreflex and arterial baroreflex function. Thirty-nine healthy subjects performed a 1-min isometric handgrip exercise at 50% of maximal voluntary contraction. This was followed by a 4-min postexercise muscle ischemia (PEMI) period to selectively maintain activation of the muscle metaboreflex. All subjects showed increases in arterial pressure during exercise. Interindividual coefficients of variation (CVs) for the changes in CO and TPR between rest and exercise periods (CO: 95.1% and TPR: 87.8%) were more than twofold greater than CVs for changes in mean arterial pressure (39.7%). There was a negative correlation between CO and TPR responses during exercise ( r = −0.751, P < 0.01), but these CO and TPR responses correlated positively with the corresponding responses during PEMI ( r = 0.568 and 0.512, respectively, P < 0.01). The CO response during exercise did not correlate with PEMI-induced changes in an index of cardiac parasympathetic tone and cardiac baroreflex sensitivity. These findings demonstrate that the changes in CO and TPR that occur in response to isometric handgrip exercise vary considerably among individuals and that the two responses have an inverse relationship. They also suggest that individual differences in components of the pressor response are attributable in part to variations in muscle metaboreflex-mediated cardioaccelerator and vasoconstrictor responses.
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Affiliation(s)
- Kazuhito Watanabe
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; and
| | - Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
| | - Rei Tahara
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; and
| | - Takeshi Nishiyasu
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan; and
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Weippert M, Behrens K, Rieger A, Stoll R, Kreuzfeld S. Heart rate variability and blood pressure during dynamic and static exercise at similar heart rate levels. PLoS One 2013; 8:e83690. [PMID: 24349546 PMCID: PMC3862773 DOI: 10.1371/journal.pone.0083690] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Accepted: 11/07/2013] [Indexed: 11/19/2022] Open
Abstract
Aim was to elucidate autonomic responses to dynamic and static (isometric) exercise of the lower limbs eliciting the same moderate heart rate (HR) response. Method: 23 males performed two kinds of voluntary exercise in a supine position at similar heart rates: static exercise (SE) of the lower limbs (static leg press) and dynamic exercise (DE) of the lower limbs (cycling). Subjective effort, systolic (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), rate pressure product (RPP) and the time between consecutive heart beats (RR-intervals) were measured. Time-domain (SDNN, RMSSD), frequency-domain (power in the low and high frequency band (LFP, HFP)) and geometric measures (SD1, SD2) as well as non-linear measures of regularity (approximate entropy (ApEn), sample entropy (SampEn) and correlation dimension D2) were calculated. Results: Although HR was similar during both exercise conditions (88±10 bpm), subjective effort, SBP, DBP, MAP and RPP were significantly enhanced during SE. HRV indicators representing overall variability (SDNN, SD 2) and vagal modulated variability (RMSSD, HFP, SD 1) were increased. LFP, thought to be modulated by both autonomic branches, tended to be higher during SE. ApEn and SampEn were decreased whereas D2 was enhanced during SE. It can be concluded that autonomic control processes during SE and DE were qualitatively different despite similar heart rate levels. The differences were reflected by blood pressure and HRV indices. HRV-measures indicated a stronger vagal cardiac activity during SE, while blood pressure response indicated a stronger sympathetic efferent activity to the vessels. The elevated vagal cardiac activity during SE might be a response mechanism, compensating a possible co-activation of sympathetic cardiac efferents, as HR and LF/HF was similar and LFP tended to be higher. However, this conclusion must be drawn cautiously as there is no HRV-marker reflecting “pure” sympathetic cardiac activity.
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Affiliation(s)
- Matthias Weippert
- Institute of Preventive Medicine, University of Rostock Medical School, Rostock, Mecklenburg-Vorpommern, Germany
- Center for Life Science Automation, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany
- * E-mail:
| | - Kristin Behrens
- Institute of Preventive Medicine, University of Rostock Medical School, Rostock, Mecklenburg-Vorpommern, Germany
| | - Annika Rieger
- Center for Life Science Automation, University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany
| | - Regina Stoll
- Institute of Preventive Medicine, University of Rostock Medical School, Rostock, Mecklenburg-Vorpommern, Germany
| | - Steffi Kreuzfeld
- Institute of Preventive Medicine, University of Rostock Medical School, Rostock, Mecklenburg-Vorpommern, Germany
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26
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Rodríguez-Zamora L, Iglesias X, Barrero A, Torres L, Chaverri D, Rodríguez FA. Monitoring internal load parameters during competitive synchronized swimming duet routines in elite athletes. J Strength Cond Res 2013; 28:742-51. [PMID: 23820563 DOI: 10.1519/jsc.0b013e3182a20ee7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of the study is to compare the heart rate (HR) and rate of perceived exertion (RPE) responses as internal load indicators while performing duet routines during training and competition, both in the technical and free programs of synchronized swimming (SS). Participants were 10 SS Olympic medalists (age, 17.4 ± 3.0 years; height, 164.0 ± 6.1 cm; body mass, 52.0 ± 6.4 kg; training, 36.3 ± 6.2 h·wk; experience, 9.2 ± 2.6 years). They were monitored while performing the same technical duet or free duet, during a training session (T) and during an official competition (C). Heart rate was continuously monitored. Rate of perceived exertion was assessed using the Borg CR10 scale. Heart rate responses during T and C were almost identical: pre-exercise mean HR (b·min) was 130.5 ± 13.9 (T) and 133.6 ± 7.7 (C) and quickly increased yielding mean peak values of 184.8 ± 5.8 (T) and 184.8 ± 6.6 (C), with interspersed bradycardic events down to 86.6 ± 4 (T) and 86.3 ± 5 (C). Routines were perceived as "hard" to "extremely hard" by the swimmers in both conditions, and mean RPE scores (0-10+) were equally high during C (7.9 ± 1.2) and T (7.5 ± 1.2) (p = 0.223). Rate of perceived exertion inversely correlated with minimum (R = -0.545; p = 0.008) and mean HR (R = -0.452; p = 0.026) and positively correlated with HRrange (R = 0.520; p = 0.011). The internal load imposed by SS duets performed during training is virtually identical to that elicited in a real competitive situation. Therefore, practicing competitive routines is suitable for developing and maintaining the cardiovascular fitness that is needed for specific conditioning in elite synchronized swimmers, with the added value of favoring exercise automaticity, interindividual coordination, and artistic expression simultaneously.
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Affiliation(s)
- Lara Rodríguez-Zamora
- INEFC-Barcelona Sports Sciences Research Group, Institut Nacional d'Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain
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Rodríguez-Zamora L, Iglesias X, Barrero A, Chaverri D, Erola P, Rodríguez FA. Physiological responses in relation to performance during competition in elite synchronized swimmers. PLoS One 2012; 7:e49098. [PMID: 23155452 PMCID: PMC3498322 DOI: 10.1371/journal.pone.0049098] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/03/2012] [Indexed: 11/26/2022] Open
Abstract
Purpose We aimed to characterize the cardiovascular, lactate and perceived exertion responses in relation to performance during competition in junior and senior elite synchronized swimmers. Methods 34 high level senior (21.4±3.6 years) and junior (15.9±1.0) synchronized swimmers were monitored while performing a total of 96 routines during an official national championship in the technical and free solo, duet and team competitive programs. Heart rate was continuously monitored. Peak blood lactate was obtained from serial capillary samples during recovery. Post-exercise rate of perceived exertion was assessed using the Borg CR-10 scale. Total competition scores were obtained from official records. Results Data collection was complete in 54 cases. Pre-exercise mean heart rate (beats·min−1) was 129.1±13.1, and quickly increased during the exercise to attain mean peak values of 191.7±8.7, with interspersed bradycardic events down to 88.8±28.5. Mean peak blood lactate (mmol·L−1) was highest in the free solo (8.5±1.8) and free duet (7.6±1.8) and lowest at the free team (6.2±1.9). Mean RPE (0–10+) was higher in juniors (7.8±0.9) than in seniors (7.1±1.4). Multivariate analysis revealed that heart rate before and minimum heart rate during the routine predicted 26% of variability in final total score. Conclusions Cardiovascular responses during competition are characterized by intense anticipatory pre-activation and rapidly developing tachycardia up to maximal levels with interspersed periods of marked bradycardia during the exercise bouts performed in apnea. Moderate blood lactate accumulation suggests an adaptive metabolic response as a result of the specific training adaptations attributed to influence of the diving response in synchronized swimmers. Competitive routines are perceived as very to extremely intense, particularly in the free solo and duets. The magnitude of anticipatory heart rate activation and bradycardic response appear to be related to performance variability.
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Affiliation(s)
- Lara Rodríguez-Zamora
- INEFC-Barcelona Sports Sciences Research Group, Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain
| | - Xavier Iglesias
- INEFC-Barcelona Sports Sciences Research Group, Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain
- * E-mail:
| | - Anna Barrero
- INEFC-Barcelona Sports Sciences Research Group, Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain
| | - Diego Chaverri
- INEFC-Barcelona Sports Sciences Research Group, Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain
| | - Pau Erola
- Departament d'Enginyeria Informàtica i Matemàtiques, Universitat Rovira i Virgili, Tarragona, Spain
| | - Ferran A. Rodríguez
- INEFC-Barcelona Sports Sciences Research Group, Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain
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Wåhlin A, Ambarki K, Hauksson J, Birgander R, Malm J, Eklund A. Phase contrast MRI quantification of pulsatile volumes of brain arteries, veins, and cerebrospinal fluids compartments: repeatability and physiological interactions. J Magn Reson Imaging 2011; 35:1055-62. [PMID: 22170792 DOI: 10.1002/jmri.23527] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Accepted: 11/08/2011] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To study measurement repeatability and physiological determinants on measurement stability for phase contrast MRI (PC-MRI) measurements of cyclic volume changes (ΔV) of brain arteries, veins, and cerebrospinal fluid (CSF) compartments. MATERIALS AND METHODS Total cerebral blood flow (tCBF), total internal jugular flow (tJBF) and spinal CSF flow at C2-C3 level and CSF in the aqueduct was measured using five repetitions in 20 healthy subjects. After subtracting net flow, waveforms were integrated to calculate ΔV of arterial, venous, and cerebrospinal fluid compartments. The intraclass correlation coefficient (ICC) was used to measure repeatability. Systematic errors were investigated by a series of phantom measurements. RESULTS For ΔV calculated from tCBF, tJBF and both CSF waveforms, the ICC was ≥0.85. ΔV from the tCBF waveform decreased linearly between repetitions (P = 0.012). Summed CSF and venous volume being shifted out from the cranium was correlated with ΔV calculated from the tCBF waveform (r = 0.75; P < 0.001). Systematic errors increased at resolutions <4 pixels per diameter. CONCLUSION Repeatability of ΔV calculated from tCBF, tJBF, and CSF waveforms allows useful interpretations. The subject's time in the MR system and imaging resolution should be considered when interpreting volume changes. Summed CSF and venous volume changes was associated with arterial volume changes.
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Affiliation(s)
- Anders Wåhlin
- Department of Radiation Sciences, Umeå University, Umeå, Sweden.
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Low-frequency fluctuations in heart rate, cardiac output and mean arterial pressure in humans: what are the physiological relationships? J Hypertens 2011; 29:1327-36. [DOI: 10.1097/hjh.0b013e328347a17a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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30
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Wong BJ, Sheriff DD. Role of splanchnic constriction in governing the hemodynamic responses to gravitational stress in conscious dogs. J Appl Physiol (1985) 2011; 111:40-7. [PMID: 21512154 DOI: 10.1152/japplphysiol.01290.2010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Octreotide is a somatostatin analog that constricts the splanchnic circulation, thereby improving orthostatic tolerance. We tested the hypotheses that octreotide improves orthostatic tolerance by 1)increasing cardiac filling (right atrial) pressure via reductions in vascular capacity; 2) by causing an upward (i.e., cranial) shift of the hydrostatic indifferent point; and 3) by increasing arterial pressure via a reduction in total vascular conductance. Studies were carried out in acepromazine-sedated, hexamethonium-treated atrioventricular-blocked conscious dogs lightly restrained in lateral recumbency. Beat-by-beat cardiac output was held constant via computer-controlled ventricular pacing at rest and during 30 s of 30° head-up tilt. Octreotide (1.5 μg/kg iv) raised right atrial pressure by 0.5 mmHg and raised mean arterial pressure by 11 mmHg by reducing total vascular conductance (all P < 0.05). Right atrial pressure fell by a similar amount in response to tilting before and after octreotide, thus there was no difference in location of the hydrostatic indifferent point. These data indicate that octreotide improves orthostatic tolerance by decreasing total vascular conductance and by increasing cardiac filling pressure via a reduction in unstressed vascular volume and not by eliciting a cranial shift of the location of the hydrostatic indifferent point.
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Affiliation(s)
- Brett J Wong
- Department of Kinesiology, Kansas State University, Manhattan, Kansas, USA
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31
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Trinity JD, McDaniel J, Venturelli M, Fjeldstad AS, Ives SJ, Witman MAH, Barrett-O'Keefe Z, Amann M, Wray DW, Richardson RS. Impact of body position on central and peripheral hemodynamic contributions to movement-induced hyperemia: implications for rehabilitative medicine. Am J Physiol Heart Circ Physiol 2011; 300:H1885-91. [PMID: 21357514 DOI: 10.1152/ajpheart.00038.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study used alterations in body position to identify differences in hemodynamic responses to passive exercise. Central and peripheral hemodynamics were noninvasively measured during 2 min of passive knee extension in 14 subjects, whereas perfusion pressure (PP) was directly measured in a subset of 6 subjects. Movement-induced increases in leg blood flow (LBF) and leg vascular conductance (LVC) were more than twofold greater in the upright compared with supine positions (LBF, supine: 462 ± 6, and upright: 1,084 ± 159 ml/min, P < 0.001; and LVC, supine: 5.3 ± 1.2, and upright: 11.8 ± 2.8 ml·min⁻¹ ·mmHg⁻¹, P < 0.002). The change in heart rate (HR) from baseline to peak was not different between positions (supine: 8 ± 1, and upright: 10 ± 1 beats/min, P = 0.22); however, the elevated HR was maintained for a longer duration when upright. Stroke volume contributed to the increase in cardiac output (CO) during the upright movement only. CO increased in both positions; however, the magnitude and duration of the CO response were greater in the upright position. Mean arterial pressure and PP were higher at baseline and throughout passive movement when upright. Thus exaggerated central hemodynamic responses characterized by an increase in stroke volume and a sustained HR response combined to yield a greater increase in CO during upright movement. This greater central response coupled with the increased PP and LVC explains the twofold greater and more sustained increase in movement-induced hyperemia in the upright compared with supine position and has clinical implications for rehabilitative medicine.
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Affiliation(s)
- Joel D Trinity
- Geriatric Research, Education, and Clinical Center, George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, USA.
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Toska K. Handgrip contraction induces a linear increase in arterial pressure by peripheral vasoconstriction, increased heart rate and a decrease in stroke volume. Acta Physiol (Oxf) 2010; 200:211-21. [PMID: 20456282 DOI: 10.1111/j.1748-1716.2010.02144.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The hypothesis that isometric handgrip induces a progressive increase in arterial pressure and a linear increase in setpoint for arterial pressure control was tested. METHODS The continuous time course of changes in heart rate (HR), stroke volume (SV) and mean arterial pressure (MAP) was recorded during a 2-min handgrip contraction of 40% of maximal voluntary contraction force. Twice during the development of the handgrip-induced, gradual pressure increase of ∼25 mmHg, additional, transient changes in arterial pressure were mechanically induced. The subsequent baroreflex responses to these additional pressure changes were studied. The additional steep increase in arterial pressure (∼10 mmHg) was induced both after 70 and 100 s of handgrip contraction, by inflating bilateral thigh cuffs to suprasystolic pressure. Cuff pressure was released after 10s, thus introducing a steep decrease in MAP. RESULTS During the development of the handgrip-induced pressure increase, HR increased, SV decreased, cardiac output (CO) increased slightly and total peripheral conductance (TPC=CO/MAP) increased (i.e. peripheral vasoconstriction). The circulatory responses to the additional, sudden increase and subsequent decrease in arterial pressure after 70 and 100 s perfectly adjusted arterial pressure back to the linear increase in MAP, indicating an effective baroreflex response. CONCLUSION The increase in MAP which characterizes handgrip-induced pressure response can be regarded as a result of a gradual increase in the set point of the arterial baroreflexes, with no change in the time course and magnitude of the baroreflex responses to additional, induced changes in MAP.
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Affiliation(s)
- K Toska
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
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Abstract
This study evaluates how mechanical factors impact cardiac output at the systemic level, and how mechanical factors influence muscle blood flow at the local level. Importantly, the two are intertwined; events that work locally in the periphery to augment muscle blood flow can also act centrally to contribute to the development of a high cardiac output.
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Affiliation(s)
- D D Sheriff
- Department of Integrative Physiology, The University of Iowa, Iowa City, IA 52242, USA.
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McDaniel J, Fjeldstad AS, Ives S, Hayman M, Kithas P, Richardson RS. Central and peripheral contributors to skeletal muscle hyperemia: response to passive limb movement. J Appl Physiol (1985) 2009; 108:76-84. [PMID: 19910331 DOI: 10.1152/japplphysiol.00895.2009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The central and peripheral contributions to exercise-induced hyperemia are not well understood. Thus, utilizing a reductionist approach, we determined the sequential peripheral and central responses to passive exercise in nine healthy men (33 +/- 9 yr). Cardiac output, heart rate, stroke volume, mean arterial pressure, and femoral blood flow of the passively moved leg and stationary (control) leg were evaluated second by second during 3 min of passive knee extension with and without a thigh cuff that occluded leg blood flow. Without the thigh cuff, significant transient increases in cardiac output (1.0 +/- 0.6 l/min, Delta15%), heart rate (7 +/- 4 beats/min, Delta12%), stroke volume (7 +/- 5 ml, Delta7%), passive leg blood flow (411 +/- 146 ml/min, Delta151%), and control leg blood flow (125 +/- 68 ml/min, Delta43%) and a transient decrease in mean arterial pressure (3 +/- 3 mmHg, 4%) occurred shortly after the onset of limb movement. Although the rise and fall rates of these variables differed, they all returned to baseline values within 45 s; therefore, continued limb movement beyond 45 s does not maintain an increase in cardiac output or net blood flow. Similar changes in the central variables occurred when blood flow to the passively moving leg was occluded. These data confirm the role of peripheral factors and reveal an essential supportive role of cardiac output in the hyperemia at the onset of passive limb movement. This cardiac output response provides an important potential link between the physiology of active and passive exercise.
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Affiliation(s)
- John McDaniel
- VA Medical Center, Bldg 2, 500 Foothill Dr., Salt Lake City, Utah 84148, USA.
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Faisal A, Beavers KR, Robertson AD, Hughson RL. Prior moderate and heavy exercise accelerate oxygen uptake and cardiac output kinetics in endurance athletes. J Appl Physiol (1985) 2009; 106:1553-63. [PMID: 19246653 DOI: 10.1152/japplphysiol.91550.2008] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cardiorespiratory interactions at the onset of dynamic cycling exercise are modified by warm-up exercises. We tested the hypotheses that oxygen uptake (Vo(2)) and cardiac output (Q) kinetics would be accelerated at the onset of heavy and moderate cycling exercise by warm-up. Nine male endurance athletes (peak Vo(2): 60.5 +/- 3.2 ml.min(-1).kg(-1)) performed multiple rides of two different 36-min cycling protocols, involving 6-min bouts at moderate and heavy intensities. Breath-by-breath Vo(2) and beat-by-beat stroke volume (SV) and Q, estimated by Modelflow from the finger pulse, were measured simultaneously with kinetics quantified from the phase II time constant (tau(2)). One novel finding was that both moderate (M) and heavy (H) warm-up bouts accelerated phase II Vo(2) kinetics during a subsequent bout of heavy exercise (tau(2): after M = 22.5 +/- 2.7 s, after H = 22.1 +/- 2.9 vs. 26.2 +/- 3.2 s; P < 0.01). Q kinetics in heavy exercise were accelerated by both warm-up intensities (tau(2): M = 22.0 +/- 4.1 s, H = 23.8 +/- 5.6 s vs. 27.4 +/- 7.2 s; P < 0.05). During moderate exercise, prior heavy-intensity warm-up (one or two bouts) accelerated Vo(2) kinetics and elevated Q at exercise onset, with no changes in Q kinetics. A second novel finding was a significant overshoot in the estimate of SV from Modelflow in the first minutes of each moderate and heavy exercise bout. These findings suggest that the acceleration of Vo(2) kinetics during heavy exercise was enabled by the acceleration of Q kinetics, and that rapid increases in Q at the onset of moderate and heavy exercise might result, in part, from an overshoot of SV.
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Affiliation(s)
- Azmy Faisal
- Faculty of Applied Health Sciences, Univ. of Waterloo, Waterloo, ON N2L3G1, Canada
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