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Johnson NE, Burma JS, Seok J, Miutz LN, Smirl JD. Influence of sex on the reliability of cerebral blood velocity regulation during lower body negative pressure and supine cycling with considerations of the menstrual cycle. Physiol Meas 2023; 44:114001. [PMID: 37848016 DOI: 10.1088/1361-6579/ad0425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 10/17/2023] [Indexed: 10/19/2023]
Abstract
Objective.To evaluate sex differences in the reliability of absolute and relative cerebral blood velocity (CBv) during concurrent supine cycling with lower body negative pressure (LBNP).Approach. A total of 19 participants (11 females; aged 20-33 years) completed five testing sessions, occurring on 7 d intervals. Visit 1 was a maximal-ramp-cycle test to ascertain peak CBv wattage. During visits 2-5, supine cycling protocol occurred at individualized peak CBv wattages with progressive decreases in LBNP from 0 to -20, -40, -60, -70, and -80 Torr. Menstrual cycle day was self-reported via the Rhinessa Women's Questionnaire. Transcranial Doppler ultrasound insonated bilateral middle cerebral artery velocity (MCAv). Two-way ANOVA assessed potential day- and sex-differences at each LBNP stage. Reliability was determined using intraclass correlation coefficients (ICC) and coefficient of variation (CoV).Main results. For all physiological measures, no main-effects were present for day- or interaction-terms (p> 0.067; negligible-to-small effect sizes), while sex differences were noted for MCAv, blood pressure, and heart rate (p< 0.046). Across visits, males and females displayed excellent and good-to-excellent levels of reliability for MCAv metrics, respectively (ICC range: 0.745-0.999; CoV range: 0.33%-9.90%).Significance. During the current investigation, both relative and absolute CBv demonstrated high reliability in both male and female participants during a supine LBNP cycling protocol. An exploratory analysis revealed increased variance was found in female participants dependent on contraceptive use. Despite this, results indicate future LBNP studies may include females at any menstrual cycle stage.
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Affiliation(s)
- Nathan E Johnson
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada
| | - Joel S Burma
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada
| | - Jina Seok
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada
| | - Lauren N Miutz
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Department of Health and Sport Science, University of Dayton, Dayton, OH, United States of America
| | - Jonathan D Smirl
- Cerebrovascular Concussion Lab, Faculty of Kinesiology, University of Calgary, Alberta, Canada
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- Libin Cardiovascular Institute of Alberta, University of Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Integrated Concussion Research Program, University of Calgary, Calgary, Alberta, Canada
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Changes in the reactivity of the vertebrobasilar arteries when using glucose-electrolyte drink with antioxidant plant extracts during submaximal exercise test. ACTA BIOMEDICA SCIENTIFICA 2023. [DOI: 10.29413/abs.2023-8.1.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023] Open
Abstract
The aim. To assess the effect of glucose-electrolyte composition with plant extracts having antioxidant activity on the hemodynamic parameters of vertebrobasilar system during the incrementally increasing submaximal exercise test.Materials and methods. The study included 12 athletes (6 candidates for master of sports and 6 masters of sports) aged 18–22, who have been engaged in orienteering for 10 years and more. Time of aerobic exercise – 2 hours a day, five days a week. The study subjects performed an incrementally increasing submaximal exercise test and also submaximal exercise test with the preventive intake of a glucose-electrolyte composition with plant extracts having antioxidant properties. To assess the hemodynamic parameters in all study subjects we used Doppler ultrasound of the cerebral vessels, evaluating vertebrobasilar system blood flow, exercise gas test in the modification of hypo- and hyperventilation, and also positional test.Results. A single intake of glucose-electrolyte drink under conditions of incrementally increasing exercise test contributed to the manifestation of a homeostatic effect in hemodynamic parameters of the vertebrobasilar arteries. It is evidenced by the approximation to the pre-exercise level of maximum systolic velocity and average blood velocity in the breath-holding test, of the diastolic blood velocity in the hyperventilation test, and of the pulsatility index in the torsion test, as compared to the isolated submaximal exercise test which caused the change in both velocity indicators and calculated indices during the functional tests.The article considers the main mechanisms underlying the change in arterial hemodynamic parameters caused by incrementally increasing load, as well as describes the proposed mechanisms arising from the combined effect of an incrementally increasing load and the intake of a glucose-electrolyte composition with plant extracts having antioxidant activity.Conclusion. It was shown that using glucose-electrolyte drink contributed to the restoration of hemodynamic parameters of the vertebrobasilar arteries after an incrementally increasing submaximal exercise test.
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Kelley EF, Cross TJ, Johnson BD. Inspiratory threshold loading negatively impacts attentional performance. Front Psychol 2022; 13:959515. [PMID: 36186373 PMCID: PMC9524251 DOI: 10.3389/fpsyg.2022.959515] [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: 06/01/2022] [Accepted: 08/26/2022] [Indexed: 11/13/2022] Open
Abstract
RationaleThere are growing concerns over the occurrence of adverse physiologic events (PEs) occurring in pilots during operation of United States Air Force and Navy high-performance aircraft. We hypothesize that a heightened inspiratory work of breathing experienced by jet pilots by virtue of the on-board life support system may constitute a “distraction stimulus” consequent to an increased sensation of respiratory muscle effort. As such, the purpose of this study was to determine whether increasing inspiratory muscle effort adversely impacts on attentional performance.MethodsTwelve, healthy participants (age: 29 ± 6 years) were recruited for this study. Participants completed six repetitions of a modified Masked Conjunctive Continuous Performance Task (MCCPT) protocol while breathing against four different inspiratory threshold loads to assess median reaction times (RTs). A computer-controlled threshold loading device was used to set the inspiratory threshold loads. Repeated measures analysis of variances (ANOVAs) were performed to examine: (i) the efficacy of the threshold loading device to impose significantly higher loading at each loading condition; (ii) the effects of loading condition on respiratory muscle effort sensation; and (iii) the influence of hypercapnia on MCCPT scores during inspiratory threshold loading. Generalized additive mixed effects models (GAMMs) were used to examine the potential non-linear effects of respiratory muscular effort sensation, device loading, and hypercapnia, on MCCPT scores during inspiratory threshold loading.ResultsInspiratory threshold loading significantly augmented (P < 0.05) inspiratory effort sensation and the inspiratory pressure-time product (PTP). Our analyses also revealed that median hit RT was positively associated with inspiratory effort sensation during inspiratory loading trials.ConclusionThe findings of this work suggest that it was not increasing inspiratory muscle effort (i.e., PTP) per se, but rather participant’s subjective perception of inspiratory “load” that impacts negatively on attentional performance; i.e., as the degree of inspiratory effort sensation increased, sotoo did median hit RT. As such, it is reasonable to suggest that minimizing inspiratory effort sensation (independent of the mechanical output of the inspiratory muscles) during high-performance flight operations may prove useful in reducing pilot RTs during complex behavioral tasks.
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Affiliation(s)
- Eli F. Kelley
- Air Force Research Laboratory (AFRL), 711HPW/RHBFP, WPAFB, Dayton, OH, United States
- *Correspondence: Eli F. Kelley,
| | - Troy J. Cross
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Bruce D. Johnson
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States
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Bozkurt S, Ayten UE. ln silico simulation of the interaction among autoregulatory mechanisms regulating cerebral blood flow rate in the healthy and systolic heart failure conditions during exercise. Med Biol Eng Comput 2022; 60:1863-1879. [DOI: 10.1007/s11517-022-02585-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 04/22/2022] [Indexed: 11/29/2022]
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Caldwell HG, Hoiland RL, Smith KJ, Brassard P, Bain AR, Tymko MM, Howe CA, Carr JM, Stacey BS, Bailey DM, Drapeau A, Sekhon MS, MacLeod DB, Ainslie PN. Trans-cerebral HCO 3- and PCO 2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans. J Cereb Blood Flow Metab 2022; 42:559-571. [PMID: 34904461 PMCID: PMC8943603 DOI: 10.1177/0271678x211065924] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO3-]) and carbon dioxide tension (PCO2) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO2 (PaCO2) (n = 39); and 2) metabolic acidosis via incremental cycling exercise to exhaustion (n = 24). During respiratory acidosis, arterial [HCO3-] increased by 0.15 ± 0.05 mmol ⋅ l-1 per mmHg elevation in PaCO2 across a wide physiological range (35 to 60 mmHg PaCO2; P < 0.001). The narrowing of the venous-arterial [HCO3-] and PCO2 differences with respiratory acidosis were both related to the hypercapnia-induced elevations in cerebral blood flow (CBF) (both P < 0.001; subset n = 27); thus, trans-cerebral [HCO3-] exchange (CBF × venous-arterial [HCO3-] difference) was reduced indicating a shift from net release toward net uptake of [HCO3-] (P = 0.004). Arterial [HCO3-] was reduced by -0.48 ± 0.15 mmol ⋅ l-1 per nmol ⋅ l-1 increase in arterial [H+] with exercise-induced acidosis (P < 0.001). There was no relationship between the venous-arterial [HCO3-] difference and arterial [H+] with exercise-induced acidosis or CBF; therefore, trans-cerebral [HCO3-] exchange was unaltered throughout exercise when indexed against arterial [H+] or pH (P = 0.933 and P = 0.896, respectively). These results indicate that increases and decreases in systemic [HCO3-] - during acute respiratory/exercise-induced metabolic acidosis, respectively - differentially affect cerebrovascular acid-base balance (via trans-cerebral [HCO3-] exchange).
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Kurt J Smith
- Department of Exercise Science, Physical and Health Education, Faculty of Education, University of Victoria, Victoria, British Columbia, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Anthony R Bain
- Faculty of Human Kinetics, Department of Kinesiology, University of Windsor, Windsor, ON, Canada
| | - Michael M Tymko
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Jay Mjr Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, 8167Vancouver General Hospital, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
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Carr JMJR, Caldwell HG, Carter H, Smith K, Tymko MM, Green DJ, Ainslie PN, Hoiland RL. The stability of cerebrovascular CO 2 reactivity following attainment of physiological steady-state. Exp Physiol 2021; 106:2542-2555. [PMID: 34730862 DOI: 10.1113/ep089982] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/14/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? During a steady-state cerebrovascular CO2 reactivity test, do different data extraction time points change the outcome for cerebrovascular CO2 reactivity? What is the main finding and its importance? Once steady-state end-tidal pressure of CO2 and haemodynamics were achieved, cerebral blood flow was stable, and so cerebrovascular CO2 reactivity values remained unchanged regardless of data extraction length (30 vs. 60 s) and time point (at 2-5 min). ABSTRACT This study assessed cerebrovascular CO2 reactivity (CVR) and examined data extraction time points and durations with the hypotheses that: (1) there would be no difference in CVR values when calculated with cerebral blood flow (CBF) measures at different time points following the attainment of physiological steady-state, (2) once steady-state was achieved there would be no difference in CVR values derived from 60 to 30 s extracted means, and (3) that changes in V ̇ E would not be associated with any changes in CVR. We conducted a single step iso-oxic hypercapnic CVR test using dynamic end-tidal forcing (end-tidal P C O 2 , +9.4 ± 0.7 mmHg), and transcranial Doppler and Duplex ultrasound of middle cerebral artery (MCA) and internal carotid artery (ICA), respectively. From the second minute of hypercapnia onwards, physiological steady-state was apparent, with no subsequent changes in end-tidal P C O 2 , P O 2 or mean arterial pressure. Therefore, CVR measured in the ICA and MCA was stable following the second minute of hypercapnia onwards. Data extraction durations of 30 or 60 s did not give statistically different CVR values. No differences in CVR were detected following the second minute of hypercapnia after accounting for mean arterial pressure via calculated conductance or covariation of mean arterial pressure. These findings demonstrate that, provided the P C O 2 stimulus remains in a steady-state, data extracted from any minute of a CVR test during physiological steady-state conditions produce equivalent CVR values; any change in the CVR value would represent a failure of CVR mechanisms, a change in the magnitude of the stimulus, or measurement error.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Howard Carter
- Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), University of Western Australia, Perth, Australia
| | - Kurt Smith
- Cerebrovascular Health, Exercise, and Environmental Research Sciences Laboratory (CHEERS), School of Exercise Science and Physical Health Education, Faculty of Education, University of Victoria, Victoria, British Columbia, Canada
| | - Michael M Tymko
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Canada
| | - Daniel J Green
- Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), University of Western Australia, Perth, Australia
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, British Columbia, Canada.,Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.,International Collaborations on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada
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Carr JMJR, Caldwell HG, Ainslie PN. Cerebral blood flow, cerebrovascular reactivity and their influence on ventilatory sensitivity. Exp Physiol 2021; 106:1425-1448. [PMID: 33932955 DOI: 10.1113/ep089446] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 04/26/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? Cerebrovascular reactivity to CO2 , which is a principal factor in determining ventilatory responses to CO2 through the role reactivity plays in determining cerebral extra- and intracellular pH. What advances does it highlight? Recent animal evidence suggests central chemoreceptor vasculature may demonstrate regionally heterogeneous cerebrovascular reactivity to CO2 , potentially as a protective mechanism against excessive CO2 washout from the central chemoreceptors, thereby allowing ventilation to reflect the systemic acid-base balance needs (respiratory changes in P aC O 2 ) rather than solely the cerebral needs. Ventilation per se does not influence cerebrovascular reactivity independent of changes in P aC O 2 . ABSTRACT Alveolar ventilation and cerebral blood flow are both predominantly regulated by arterial blood gases, especially arterial P C O 2 , and so are intricately entwined. In this review, the fundamental mechanisms underlying cerebrovascular reactivity and central chemoreceptor control of breathing are covered. We discuss the interaction of cerebral blood flow and its reactivity with the control of ventilation and ventilatory responsiveness to changes in P C O 2 , as well as the lack of influence of ventilation itself on cerebrovascular reactivity. We briefly summarize the effects of arterial hypoxaemia on the relationship between ventilatory and cerebrovascular response to both P C O 2 and P O 2 . We then highlight key methodological considerations regarding the interaction of reactivity and ventilatory sensitivity, including the following: regional heterogeneity of cerebrovascular reactivity; a pharmacological approach for the reduction of cerebral blood flow; reactivity assessment techniques; the influence of mean arterial blood pressure; and sex-related differences. Finally, we discuss ventilatory and cerebrovascular control in the context of high altitude and congestive heart failure. Future research directions and pertinent questions of interest are highlighted throughout.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
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Tarumi T, Yamabe T, Fukuie M, Zhu DC, Zhang R, Ogoh S, Sugawara J. Brain blood and cerebrospinal fluid flow dynamics during rhythmic handgrip exercise in young healthy men and women. J Physiol 2021; 599:1799-1813. [PMID: 33481257 DOI: 10.1113/jp281063] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/12/2021] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS The cerebral fluid response to exercise, including the arterial and venous cerebral blood flow (CBF) and cerebrospinal fluid (CSF), currently remains unknown. We used time-resolved phase-contrast magnetic resonance imaging to assess changes in CBF and CSF flow dynamics during moderate-intensity rhythmic handgrip (RHG) exercise in young healthy men and women. Our data demonstrated that RHG increases the cerebral arterial inflow and venous outflow while decreasing the pulsatile CSF flow during RHG. Furthermore, changes in blood stroke volume at the measured arteries, veins, and sinuses and CSF stroke volume at the cerebral aqueduct were positively correlated with each other during RHG. Male and female participants exhibited distinct blood pressure responses to RHG, but their cerebral fluid responses were similar. These results collectively suggest that RHG influences both CBF and CSF flow dynamics in a way that is consistent with the Monro-Kellie hypothesis to maintain intracranial volume-pressure homeostasis in young healthy adults. ABSTRACT Cerebral blood flow (CBF) increases during exercise, but its impact on cerebrospinal fluid (CSF) flow remains unknown. This study investigated CBF and CSF flow dynamics during moderate-intensity rhythmic handgrip (RHG) exercise in young healthy men and women. Twenty-six participants (12 women) underwent the RHG and resting control conditions in random order. Participants performed 3 sets of RHG, during which cine phase-contrast magnetic resonance imaging (PC-MRI) was performed to measure blood stroke volume (SV) and flow rate in the internal carotid (ICA) and vertebral (VA) arteries, the internal jugular vein (IJV), the superior sagittal (SSS) and straight sinuses (SRS), and CSF SV and flow rate in the cerebral aqueduct of Sylvius. Blood pressure, end-tidal CO2 (EtCO2 ), heart rate (HR), and respiratory rate were simultaneously measured during cine PC-MRI scans. Compared with control conditions, RHG showed significant elevations of HR, mean arterial pressure, and respiratory rate with a mild reduction of EtCO2 (all P < 0.05). RHG decreased blood SV in the measured arteries, veins, and sinuses and CSF SV in the aqueduct (all P < 0.05). Conversely, RHG increased blood flow in the ICA, VA, and IJV (all P < 0.05). At the aqueduct, RHG decreased the absolute CSF flow rate (P = 0.0307), which was calculated as a sum of the caudal and cranial CSF flow rates. Change in the ICA SV was positively correlated with changes in the IJV, SSS, SRS, and aqueductal SV during RHG (all P < 0.05). These findings demonstrate a close coupling between the CBF and CSF flow dynamics during RHG in young healthy adults.
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Affiliation(s)
- Takashi Tarumi
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.,Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA
| | - Takayuki Yamabe
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
| | - Marina Fukuie
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
| | - David C Zhu
- Department of Radiology and Cognitive Imaging Research Center, Michigan State University, East Lansing, Michigan, USA
| | - Rong Zhang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Texas, USA.,Department of Neurology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-shi, Saitama, Japan
| | - Jun Sugawara
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
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Williams JS, Dunford EC, Cheng JL, Moncion K, Valentino SE, Droog CA, Cherubini JM, King TJ, Noguchi KS, Wiley E, Turner JR, Tang A, Al-Khazraji BK, MacDonald MJ. The impact of the 24-h movement spectrum on vascular remodeling in older men and women: a review. Am J Physiol Heart Circ Physiol 2021; 320:H1136-H1155. [PMID: 33449851 DOI: 10.1152/ajpheart.00754.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Aging is associated with increased risk of cardiovascular and cerebrovascular events, which are preceded by early, negative remodeling of the vasculature. Low physical activity is a well-established risk factor associated with the incidence and development of disease. However, recent physical activity literature indicates the importance of considering the 24-h movement spectrum. Therefore, the purpose of this review was to examine the impact of the 24-h movement spectrum, specifically physical activity (aerobic and resistance training), sedentary behavior, and sleep, on cardiovascular and cerebrovascular outcomes in older adults, with a focus on recent evidence (<10 yr) and sex-based considerations. The review identifies that both aerobic training and being physically active (compared with sedentary) are associated with improvements in endothelial function, arterial stiffness, and cerebrovascular function. Additionally, there is evidence of sex-based differences in endothelial function: a blunted improvement in aerobic training in postmenopausal women compared with men. While minimal research has been conducted in older adults, resistance training does not appear to influence arterial stiffness. Poor sleep quantity or quality are associated with both impaired endothelial function and increased arterial stiffness. Finally, the review highlights mechanistic pathways involved in the regulation of vascular and cerebrovascular function, specifically the balance between pro- and antiatherogenic factors, which mediate the relationship between the 24-h movement spectrum and vascular outcomes. Finally, this review proposes future research directions: examining the role of duration and intensity of training, combining aerobic and resistance training, and exploration of sex-based differences in cardiovascular and cerebrovascular outcomes.
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Affiliation(s)
- Jennifer S Williams
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Emily C Dunford
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Jem L Cheng
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Kevin Moncion
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Sydney E Valentino
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Connor A Droog
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Joshua M Cherubini
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Trevor J King
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Kenneth S Noguchi
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Elise Wiley
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Joshua R Turner
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Ada Tang
- MacStroke Canada, School of Rehabilitation Sciences, McMaster University, Hamilton, Ontario, Canada
| | | | - Maureen J MacDonald
- Vascular Dynamics Lab, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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Komiyama T, Tanoue Y, Sudo M, Costello JT, Uehara Y, Higaki Y, Ando S. Cognitive Impairment during High-Intensity Exercise: Influence of Cerebral Blood Flow. Med Sci Sports Exerc 2020; 52:561-568. [PMID: 31609297 DOI: 10.1249/mss.0000000000002183] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
PURPOSE Cognitive performance appears to be impaired during high-intensity exercise, and this occurs concurrently with a reduction in cerebral blood flow (CBF). However, it is unclear whether cognitive impairment during high-intensity exercise is associated with reduced CBF. We tested the hypothesis that a reduction in CBF is responsible for impaired cognitive performance during high-intensity exercise. METHODS Using a randomized crossover design 17 healthy males performed spatial delayed response and Go/No-Go tasks in three conditions (exercise [EX], exercise+CO2 [EX+CO2], and a nonexercising control [CON]). In the EX and EX+CO2, they performed cognitive tasks at rest and during 8 min of moderate and high-intensity exercise. Exercise intensity corresponded to ~50% (moderate) and ~80% (high) of peak oxygen uptake. In the EX+CO2, the participants inspired hypercapnic gas (2% CO2) during high-intensity exercise. In the CON, they performed the cognitive tasks without exercise. RESULTS Middle cerebral artery mean velocity increased during high-intensity exercise in the EX+CO2 relative to the EX (69.4 [10.6] cm·s, vs 57.2 [7.7] cm·s, P < 0.001). Accuracy of the cognitive tasks was impaired during high-intensity exercise in the EX (84.1% [13.3%], P < 0.05) and the EX+ CO2 (85.7 [11.6%], P < 0.05) relative to rest (EX: 95.1% [5.3%], EX+CO2: 95.1 [5.3%]). However, no differences between the EX and the EX+CO2 were observed (P > 0.10). These results demonstrate that restored CBF did not prevent cognitive impairment during high-intensity exercise. CONCLUSIONS We conclude that a reduction in CBF is not responsible for impaired cognitive performance during high-intensity exercise.
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Affiliation(s)
| | - Yukiya Tanoue
- Graduate School of Sports and Health Science, Fukuoka University, Fukuoka, JAPAN
| | - Mizuki Sudo
- Meiji Yasuda Life Foundation of Health and Welfare, Tokyo, JAPAN
| | - Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UNITED KINGDOM
| | | | - Yasuki Higaki
- Faculty of Sports Science, Fukuoka University, Fukuoka, JAPAN
| | - Soichi Ando
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, JAPAN
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11
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Howe CA, Caldwell HG, Carr J, Nowak‐Flück D, Ainslie PN, Hoiland RL. Cerebrovascular reactivity to carbon dioxide is not influenced by variability in the ventilatory sensitivity to carbon dioxide. Exp Physiol 2020; 105:904-915. [DOI: 10.1113/ep088192] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 02/20/2020] [Indexed: 01/01/2023]
Affiliation(s)
- Connor A. Howe
- Centre for HeartLung and Vascular HealthUniversity of British Columbia – Okanagan CampusSchool of Health and Exercise Sciences 3333 University Way Kelowna BC Canada V1V 1V7
| | - Hannah G. Caldwell
- Centre for HeartLung and Vascular HealthUniversity of British Columbia – Okanagan CampusSchool of Health and Exercise Sciences 3333 University Way Kelowna BC Canada V1V 1V7
| | - Jay Carr
- Centre for HeartLung and Vascular HealthUniversity of British Columbia – Okanagan CampusSchool of Health and Exercise Sciences 3333 University Way Kelowna BC Canada V1V 1V7
| | - Daniela Nowak‐Flück
- Centre for HeartLung and Vascular HealthUniversity of British Columbia – Okanagan CampusSchool of Health and Exercise Sciences 3333 University Way Kelowna BC Canada V1V 1V7
| | - Philip N. Ainslie
- Centre for HeartLung and Vascular HealthUniversity of British Columbia – Okanagan CampusSchool of Health and Exercise Sciences 3333 University Way Kelowna BC Canada V1V 1V7
| | - Ryan L. Hoiland
- Centre for HeartLung and Vascular HealthUniversity of British Columbia – Okanagan CampusSchool of Health and Exercise Sciences 3333 University Way Kelowna BC Canada V1V 1V7
- Department of Anesthesiology, Pharmacology, and TherapeuticsVancouver General HospitalWest 12th Avenue, University of British Columbia Vancouver BC Canada V5Z 1M9
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12
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Abstract
People undertaking prolonged vigorous exercise experience substantial bodily fluid losses due to thermoregulatory sweating. If these fluid losses are not replaced, endurance capacity may be impaired in association with a myriad of alterations in physiological function, including hyperthermia, hyperventilation, cardiovascular strain with reductions in brain, skeletal muscle and skin blood perfusion, greater reliance on muscle glycogen and cellular metabolism, alterations in neural activity and, in some conditions, compromised muscle metabolism and aerobic capacity. The physiological strain accompanying progressive exercise-induced dehydration to a level of ~ 4% of body mass loss can be attenuated or even prevented by: (1) ingesting fluids during exercise, (2) exercising in cold environments, and/or (3) working at intensities that require a small fraction of the overall body functional capacity. The impact of dehydration upon physiological function therefore depends on the functional demand evoked by exercise and environmental stress, as cardiac output, limb blood perfusion and muscle metabolism are stable or increase during small muscle mass exercise or resting conditions, but are impaired during whole-body moderate to intense exercise. Progressive dehydration is also associated with an accelerated drop in perfusion and oxygen supply to the human brain during submaximal and maximal endurance exercise. Yet their consequences on aerobic metabolism are greater in the exercising muscles because of the much smaller functional oxygen extraction reserve. This review describes how dehydration differentially impacts physiological function during exercise requiring low compared to high functional demand, with an emphasis on the responses of the human brain, heart and skeletal muscles.
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13
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Caldwell HG, Coombs GB, Howe CA, Hoiland RL, Patrician A, Lucas SJ, Ainslie PN. Evidence for temperature‐mediated regional increases in cerebral blood flow during exercise. J Physiol 2020; 598:1459-1473. [DOI: 10.1113/jp278827] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 12/20/2019] [Indexed: 12/18/2022] Open
Affiliation(s)
- Hannah G. Caldwell
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Geoff B. Coombs
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Connor A. Howe
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Ryan L. Hoiland
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Alexander Patrician
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Samuel J.E. Lucas
- School of Sport Exercise and Rehabilitation Sciences & Centre for Human Brain Health University of Birmingham Birmingham UK
| | - Philip N. Ainslie
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
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14
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Robertson AD, Atwi S, Kostoglou K, Verhoeff NPLG, Oh PI, Mitsis GD, Marzolini S, MacIntosh BJ. Cerebrovascular Pulsatility During Rest and Exercise Reflects Hemodynamic Impairment in Stroke and Cerebral Small Vessel Disease. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:3116-3127. [PMID: 31570171 DOI: 10.1016/j.ultrasmedbio.2019.08.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/24/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
Although aerobic exercise is recommended as a core component of stroke rehabilitation, knowledge of acute cerebrovascular responses in patients is limited. This study tested the hypothesis that older adults with chronic stroke or cerebral small vessel disease (SVD) exhibit a greater increase in pulsatile hemodynamics during exercise compared with young and age-matched healthy adults. Middle cerebral artery blood flow velocity was acquired during 20 min of moderate intensity cycling in 51 participants from four groups (young, old, SVD and stroke). During rest, only the stroke group had a higher pulsatility index (PI) compared with the young group (1.02 ± 0.17 vs 0.83 ± 0.13; p = 0.038). During exercise, however, the SVD group exhibited a larger increase in PI (68 ± 20% relative to rest) than the young (47 ± 19%), old (45 ± 17%) and stroke (40 ± 25%) groups (p < 0.05, for each). The stress of aerobic exercise may reveal arterial dysfunction associated with latent and overt cerebrovascular disease.
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Affiliation(s)
- Andrew D Robertson
- Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, Ottawa, Ontario, Canada; Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.
| | - Sarah Atwi
- Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, Ottawa, Ontario, Canada; Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Kyriaki Kostoglou
- Department of Electrical, Computer and Software Engineering, McGill University, Montreal, Quebec, Canada
| | - Nicolaas Paul L G Verhoeff
- Department of Psychiatry, Division of Geriatric Psychiatry, University of Toronto, Toronto, Ontario, Canada; Sam and Ida Ross Memory Disorders Clinic, Baycrest Health Sciences, Toronto, Ontario, Canada
| | - Paul I Oh
- Toronto Rehab, University Health Network, Toronto Ontario, Canada; Peter Munk Cardiac Centre, University of Toronto, Toronto, Ontario, Canada
| | - Georgios D Mitsis
- Department of Bioengineering, McGill University, Montreal, Quebec, Canada
| | - Susan Marzolini
- Toronto Rehab, University Health Network, Toronto Ontario, Canada
| | - Bradley J MacIntosh
- Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, Ottawa, Ontario, Canada; Hurvitz Brain Sciences Program, Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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15
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Smith KJ, Moreno-Suarez I, Scheer A, Dembo L, Naylor LH, Maiorana AJ, Green DJ. Cerebral blood flow responses to exercise are enhanced in left ventricular assist device patients after an exercise rehabilitation program. J Appl Physiol (1985) 2019; 128:108-116. [PMID: 31774355 DOI: 10.1152/japplphysiol.00604.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cerebral blood flow during exercise is impaired in patients with heart failure implanted with left ventricular assist devices (LVADs). Our aim was to determine whether a 3-mo exercise training program could mitigate cerebrovascular dysfunction. Internal carotid artery (ICA) blood flow and intracranial middle (MCAv) and posterior cerebral (PCAv) artery velocities were measured continuously using Doppler ultrasound, alongside cardiorespiratory measures at rest and in response to an incremental cycle ergometer exercise protocol in 12 LVAD participants (5 female, 53.6 ± 11.8 yr; 84.2 ± 15.7 kg; 1.73 ± 0.08) pre- (PreTR) and post- (PostTR) completion of a 3-mo supervised exercise rehabilitation program. At rest, only PCAv was different PostTR (38.1 ± 10.4 cm/s) compared with PreTR (43.0 ± 10.8 cm/s; P < 0.05). PreTR, the reduction in PCAv observed from rest to exercise (5.2 ± 1.8%) was mitigated PostTR (P < 0.001). Similarly, exercise training enhanced ICA flow during submaximal exercise (~8.6 ± 13.7%), resulting in increased ICA flow PostTR compared with a reduced flow PreTR (P < 0.001). Although both end-tidal partial pressure of carbon dioxide and mean arterial pressure responses during incremental exercise were greater PostTR than PreTR, only the improved PETCO2 was related to the improved ICA flow (R2 = 0.14; P < 0.05). Our findings suggest that short-term exercise training improves cerebrovascular function during exercise in patients with LVADs. This finding should encourage future studies investigating long-term exercise training and cerebral and peripheral vascular adaptation.NEW & NOTEWORTHY Left ventricular assist devices, now used as destination therapy in end-stage heart failure, enable patients to undertake rehabilitative exercise training. We show, for the first time in humans, that training improves cerebrovascular function during exercise in patients with left ventricular assist devices. This finding may have implications for cerebrovascular health in patients with heart failure.
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Affiliation(s)
- Kurt J Smith
- Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia.,School of Kinesiology, Lakehead University, Thunder Bay, Canada
| | | | - Anna Scheer
- School of Physiotherapy and Exercise Science, Curtin University, Bentley, Australia
| | - Lawrence Dembo
- Allied Health Department and Advanced Heart Failure and Cardiac Transplant Service, Fiona Stanley Hospital, Murdoch, Australia
| | - Louise H Naylor
- Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia.,Allied Health Department and Advanced Heart Failure and Cardiac Transplant Service, Fiona Stanley Hospital, Murdoch, Australia
| | - Andrew J Maiorana
- School of Physiotherapy and Exercise Science, Curtin University, Bentley, Australia.,Allied Health Department and Advanced Heart Failure and Cardiac Transplant Service, Fiona Stanley Hospital, Murdoch, Australia
| | - Daniel J Green
- Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia
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16
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Hansen RK, Nielsen PS, Schelske MW, Secher NH, Volianitis S. CO 2 supplementation dissociates cerebral oxygenation and middle cerebral artery blood velocity during maximal cycling. Scand J Med Sci Sports 2019; 30:399-407. [PMID: 31650627 DOI: 10.1111/sms.13582] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/28/2019] [Accepted: 10/21/2019] [Indexed: 12/15/2022]
Abstract
This study evaluated whether the reduction of prefrontal cortex oxygenation (ScO2 ) during maximal exercise depends on the hyperventilation-induced hypocapnic attenuation of middle cerebral artery blood velocity (MCA Vmean ). Twelve endurance-trained males (age: 25 ± 3 years, height: 183 ± 8 cm, weight: 75 ± 9 kg; mean ± SD) performed in three separate laboratory visits, a maximal oxygen uptake (VO2 max) test, an isocapnic (end-tidal CO2 tension (PetCO2 ) clamped at 40 ± 1 mmHg), and an ambient air controlled-pace constant load high-intensity ergometer cycling to exhaustion, while MCA Vmean (transcranial Doppler ultrasound) and ScO2 (near-infrared spectroscopy) were determined. Duration of exercise (12 min 25 s ± 1 min 18 s) was matched by performing the isocapnic trial first. Pulmonary VO2 was 90 ± 6% versus 93 ± 5% of the maximal value (P = .012) and PetCO2 40 ± 1 versus 34 ± 4 mmHg (P < .05) during the isocapnic and control trials, respectively. During the isocapnic trial MCA Vmean increased by 16 ± 13% until clamping was applied and continued to increase (by 14 ± 28%; P = .017) until the end of exercise, while there was no significant change during the control trial (P = .071). In contrast, ScO2 decreased similarly in both trials (-3.2 ± 5.1% and -4.1 ± 9.6%; P < .001, isocapnic and control, respectively) at exhaustion. The reduction in prefrontal cortex oxygenation during maximal exercise does not depend solely on lowered cerebral blood flow as indicated by middle cerebral blood velocity.
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Affiliation(s)
- Rasmus K Hansen
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Peter S Nielsen
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Markus W Schelske
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Niels H Secher
- Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Stefanos Volianitis
- Sport Sciences, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.,Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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17
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Smith KJ, Hoiland RL, Grove R, McKirdy H, Naylor L, Ainslie PN, Green DJ. Matched increases in cerebral artery shear stress, irrespective of stimulus, induce similar changes in extra-cranial arterial diameter in humans. J Cereb Blood Flow Metab 2019; 39:849-858. [PMID: 29125372 PMCID: PMC6501503 DOI: 10.1177/0271678x17739220] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The mechanistic role of arterial shear stress in the regulation of cerebrovascular responses to physiological stimuli (exercise and hypercapnia) is poorly understood. We hypothesised that, if shear stress is a key regulator of arterial dilation, then matched increases in shear, induced by distinct physiological stimuli, would trigger similar dilation of the large extra-cranial arteries. Participants ( n = 10) participated in three 30-min experimental interventions, each separated by ≥48 h: (1) mild-hypercapnia (FICO2:∼0.045); (2) submaximal cycling (EX; 60%HRreserve); or (3) resting (time-matched control, CTRL). Blood flow, diameter, and shear rate were assessed (via Duplex ultrasound) in the internal carotid and vertebral arteries (ICA, VA) at baseline, during and following the interventions. Hypercapnia and EX produced similar elevations in blood flow and shear rate through the ICA and VA ( p < 0.001), which were both greater than CTRL. Vasodilation of ICA and VA diameter in response to hypercapnia (5.3 ± 0.8 and 4.4 ± 2.0%) and EX (4.7 ± 0.7 and 4.7 ± 2.2%) were similar, and greater than CTRL ( p < 0.001). Our findings indicate that matched levels of shear, irrespective of their driving stimulus, induce similar extra-cranial artery dilation. We demonstrate, for the first time in humans, an important mechanistic role for the endothelium in regulating cerebrovascular response to common physiological stimuli in vivo.
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Affiliation(s)
- Kurt J Smith
- 1 Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia
| | - Ryan L Hoiland
- 2 Centre for Hearth Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Ryan Grove
- 1 Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia
| | - Hamish McKirdy
- 1 Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia
| | - Louise Naylor
- 1 Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia
| | - Philip N Ainslie
- 2 Centre for Hearth Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Daniel J Green
- 1 Cardiovascular Research Group, School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Perth, Australia.,3 Research Institute for Sport and Exercise Sciences, John Moores Liverpool University, UK
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18
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SMITH KURTJ, SUAREZ IGNACIOM, SCHEER ANNA, CHASLAND LAURENC, THOMAS HANNAHJ, CORREIA MARILIAA, DEMBO LAWRENCEG, NAYLOR LOUISEH, MAIORANA ANDREWJ, GREEN DANIELJ. Cerebral Blood Flow during Exercise in Heart Failure: Effect of Ventricular Assist Devices. Med Sci Sports Exerc 2019; 51:1372-1379. [DOI: 10.1249/mss.0000000000001904] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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19
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Rieger MG, Nowak-Flück D, Morris LE, Niroula S, Sherpa KT, Tallon CM, Stembridge M, Ainslie PN, McManus AM. UBC-Nepal Expedition: Cerebrovascular Responses to Exercise in Sherpa Children Residing at High Altitude. High Alt Med Biol 2019; 20:45-55. [PMID: 30648898 DOI: 10.1089/ham.2018.0083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Understanding the process of successful adaptation to high altitude provides valuable insight into the pathogenesis of conditions associated with impaired oxygen uptake and utilization. Prepubertal children residing at low altitude show a reduced cerebrovascular response to exercise in comparison to adults, and a transient uncoupling of cerebral blood flow to changes in the partial pressure of end-tidal CO2 (PETCO2); however, little is known about the cerebrovascular response to exercise in high-altitude native children. We sought to compare the cerebral hemodynamic response to acute exercise between prepubertal children residing at high and low altitude. Prepubertal children (n = 32; 17 female) of Sherpa descent (Sherpa children [SC]) at high altitude (3800 m, Nepal) and maturational-matched (n = 32; 20 female) children (lowland children [LLC]) residing at low altitude (342 m, Canada). Ventilation, peripheral oxygen saturation (SpO2), PETCO2, and blood velocity in the middle and posterior cerebral arteries (MCAv and PCAv) were continuously measured during a graded cycling exercise test to exhaustion. At baseline (BL), PETCO2 (-19 ± 4 mmHg, p < 0.001), SpO2 (-6.0% ± 2.1%, p < 0.001), MCAv (-12% ± 5%, p = 0.02), and PCAv (-12% ± 6%, p = 0.04) were lower in SC when compared with LLC. Despite this, the relative change in MCAv and PCAv during exercise was similar between the two groups (p = 0.99). Linear regression analysis demonstrated a positive relationship between changes in PETCO2 with MCAv in SC (R2 = 0.13, p > 0.001), but not in LLC (R2 = 0.03, p = 0.10). Our findings demonstrate a similar increase in intra-cranial perfusion during exercise in prepubertal SC, despite differential BL values and changes in PETCO2 and SpO2.
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Affiliation(s)
- Mathew G Rieger
- 1 Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Daniela Nowak-Flück
- 1 Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Laura E Morris
- 1 Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Shailesh Niroula
- 2 Institute of Medicine, Tribhuvan University, Kathmandu, Nepal.,3 Khunde Hospital, Khunde, Nepal
| | | | - Christine M Tallon
- 1 Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Mike Stembridge
- 4 Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Philip N Ainslie
- 1 Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
| | - Ali M McManus
- 1 Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada
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20
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Stone RM, Ainslie PN, Kerstens TP, Wildfong KW, Tymko MM. Sex differences in the circulatory responses to an isocapnic cold pressor test. Exp Physiol 2018; 104:295-305. [PMID: 30578582 DOI: 10.1113/ep087232] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 12/19/2018] [Indexed: 01/04/2023]
Abstract
NEW FINDINGS What is the central question of this study? Do sex differences exist in the cardiorespiratory responses to an isocapnic cold pressor test (CPT)? What is the main finding and its importance? During the CPT, there were no sex differences in the respiratory response; however, females demonstrated a reduced mean arterial pressure and reduced dilatation of the common carotid artery. Given that the CPT is predictive of future cardiovascular events, these data have clinical implications for improving the utility of the CPT to determine cardiovascular health risk. Sex differences should be taken into consideration when conducting and interpreting a CPT. ABSTRACT The cold pressor test (CPT) elicits a transient increase in sympathetic nervous activity, minute ventilation ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:mi>E</mml:mi></mml:msub> </mml:math> ), mean arterial pressure (MAP) and common carotid artery (CCA) diameter in healthy individuals. Although the extent of dilatation of the CCA in response to the CPT has been used as a clinical indicator of cardiovascular health status, the potential sex differences have yet to be explored. In response to a CPT, we hypothesized that elevations in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:mi>E</mml:mi></mml:msub> </mml:math> and MAP and dilatation of the CCA would be attenuated in females compared with males. In 20 young, healthy participants (10 females), we measured the respiratory, cardiovascular and CCA responses during a CPT, which consisted of a 3 min immersion of the right foot into 0-1 ice water. Blood pressure (via finger photoplethysmography), heart rate (via electrocardiogram) and CCA diameter and velocity (via Duplex ultrasound) were simultaneously recorded immediately before and during the CPT. During the CPT, while controlling end-tidal gases to baseline values, the main findings were as follows: (i) no sex differences were present in absolute or relative changes in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:mi>E</mml:mi></mml:msub> </mml:math> (P = 0.801 and P = 0.179, respectively); (ii) the relative MAP and CCA diameter response were reduced in females by 51 and 55%, respectively (P = 0.008 and P = 0.029 versus males, respectively); and (iii) the relative MAP responses was positively correlated with the dilatation of the CCA in males (r = 0.42, P = 0.019), in females (r = 0.43, P = 0.019) and in males and females combined (r = 0.55, P < 0.001). Given that the CPT is used as a clinical tool to assess cardiovascular health status, sex differences should be considered in future studies.
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Affiliation(s)
- Rachel M Stone
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Thijs P Kerstens
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kevin W Wildfong
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
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21
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Nowak-Flück D, Ainslie PN, Bain AR, Ahmed A, Wildfong KW, Morris LE, Phillips AA, Fisher JP. Effect of healthy aging on cerebral blood flow, CO2 reactivity, and neurovascular coupling during exercise. J Appl Physiol (1985) 2018; 125:1917-1930. [DOI: 10.1152/japplphysiol.00050.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We sought to make the first comparisons of duplex Doppler ultrasonography-derived measures of cerebral blood flow during exercise in young and older individuals and to assess whether healthy aging influences the effect of exercise on neurovascular coupling (NVC) and cerebral vascular reactivity to changes in carbon dioxide (CVRco2). In 10 healthy young (23 ± 2 yr; mean ± SD) and 9 healthy older (66 ± 3 yr) individuals, internal carotid artery (ICA) and vertebral artery (VA) blood flows were concurrently measured, along with middle and posterior cerebral artery mean blood velocity (MCAvmean and PCAvmean). Measures were made at rest and during leg cycling (75 W and 35% maximum aerobic workload). ICA and VA blood flow during dynamic exercise, undertaken at matched absolute (ICA: young 336 ± 95, older 352 ± 155; VA: young 95 ± 43, older 100 ± 30 ml/min) and relative (ICA: young 355 ± 125, older 323 ± 153; VA: young 115 ± 48, older 110 ± 32 ml/min) intensities, were not different between groups ( P > 0.670). The PCAvmean responses to visual stimulation (NVC) were blunted in older versus younger group at rest (16 ± 6% vs. 23 ± 7%, P < 0.026) and exercise; however, these responses were not changed from rest to exercise in either group. The ICA and VA CVRco2 were comparable in both groups and unaltered during exercise. Collectively, our findings suggest that 1) ICA and VA blood flow responses to dynamic exercise are similar in healthy young and older individuals, 2) NVC is blunted in healthy older individuals at rest and exercise but is not different between rest to exercise in either group, and 3) CVRco2 is similar during exercise in healthy young and older groups. NEW & NOTEWORTHY Internal carotid artery and vertebral artery blood flow responses to dynamic exercise are similar in healthy young and older individuals. Neurovascular coupling and cerebrovascular carbon dioxide reactivity, two key mechanisms mediating the cerebral blood flow responses to exercise, are generally unaffected by exercise in both healthy young and older individuals.
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Affiliation(s)
- Daniela Nowak-Flück
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Anthony R. Bain
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Amar Ahmed
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Kevin W. Wildfong
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Laura E. Morris
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Aaron A. Phillips
- Departments of Physiology and Pharmacology and Clinical Neurosciences, Libin Cardiovascular Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - James P. Fisher
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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22
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The Effects of Hyperoxia on Sea-Level Exercise Performance, Training, and Recovery: A Meta-Analysis. Sports Med 2018; 48:153-175. [PMID: 28975517 DOI: 10.1007/s40279-017-0791-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Acute exercise performance can be limited by arterial hypoxemia, such that hyperoxia may be an ergogenic aid by increasing tissue oxygen availability. Hyperoxia during a single bout of exercise performance has been examined using many test modalities, including time trials (TTs), time to exhaustion (TTE), graded exercise tests (GXTs), and dynamic muscle function tests. Hyperoxia has also been used as a long-term training stimulus or a recovery intervention between bouts of exercise. However, due to the methodological differences in fraction of inspired oxygen (FiO2), exercise type, training regime, or recovery protocols, a firm consensus on the effectiveness of hyperoxia as an ergogenic aid for exercise training or recovery remains unclear. OBJECTIVES The aims of this study were to (1) determine the efficacy of hyperoxia as an ergogenic aid for exercise performance, training stimulus, and recovery before subsequent exercise; and (2) determine if a dose-response exists between FiO2 and exercise performance improvements. DATA SOURCE The PubMed, Web of Science, and SPORTDiscus databases were searched for original published articles up to and including 8 September 2017, using appropriate first- and second-order search terms. STUDY SELECTION English-language, peer-reviewed, full-text manuscripts using human participants were reviewed using the process identified in the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. DATA EXTRACTION Data for the following variables were obtained by at least two of the authors: FiO2, wash-in time for gas, exercise performance modality, heart rate, cardiac output, stroke volume, oxygen saturation, arterial and/or capillary lactate, hemoglobin concentration, hematocrit, arterial pH, arterial oxygen content, arterial partial pressure of oxygen and carbon dioxide, consumption of oxygen and carbon dioxide, minute ventilation, tidal volume, respiratory frequency, ratings of perceived exertion of breathing and exercise, and end-tidal oxygen and carbon dioxide partial pressures. DATA GROUPING Data were grouped into type of intervention (acute exercise, recovery, and training), and performance data were grouped into type of exercise (TTs, TTE, GXTs, dynamic muscle function), recovery, and training in hyperoxia. DATA ANALYSIS Hedges' g effect sizes and 95% confidence intervals were calculated. Separate Pearson's correlations were performed comparing the effect size of performance versus FiO2, along with the effect size of arterial content of oxygen, arterial partial pressure of oxygen, and oxygen saturation. RESULTS Fifty-one manuscripts were reviewed. The most common FiO2 for acute exercise was 1.00, with GXTs the most investigated exercise modality. Hyperoxia had a large effect improving TTE (g = 0.89), and small-to-moderate effects increasing TTs (g = 0.56), GXTs (g = 0.40), and dynamic muscle function performance (g = 0.28). An FiO2 ≥ 0.30 was sufficient to increase general exercise performance to a small effect or higher; a moderate positive correlation (r = 0.47-0.63) existed between performance improvement of TTs, TTE, and dynamic muscle function tests and FiO2, but not GXTs (r = 0.06). Exercise training and recovery supplemented with hyperoxia trended towards a large and small ergogenic effect, respectively, but the large variability and limited amount of research on these topics prevented a definitive conclusion. CONCLUSION Acute exercise performance is increased with hyperoxia. An FiO2 ≥ 0.30 appears to be beneficial for performance, with a higher FiO2 being correlated to greater performance improvement in TTs, TTE, and dynamic muscle function tests. Exercise training and recovery supplemented with hyperoxic gas appears to have a beneficial effect on subsequent exercise performance, but small sample size and wide disparity in experimental protocols preclude definitive conclusions.
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23
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Steventon JJ, Hansen AB, Whittaker JR, Wildfong KW, Nowak-Flück D, Tymko MM, Murphy K, Ainslie PN. Cerebrovascular Function in the Large Arteries Is Maintained Following Moderate Intensity Exercise. Front Physiol 2018; 9:1657. [PMID: 30519192 PMCID: PMC6258791 DOI: 10.3389/fphys.2018.01657] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/02/2018] [Indexed: 01/13/2023] Open
Abstract
Exercise has been shown to induce cerebrovascular adaptations. However, the underlying temporal dynamics are poorly understood, and regional variation in the vascular response to exercise has been observed in the large cerebral arteries. Here, we sought to measure the cerebrovascular effects of a single 20-min session of moderate-intensity exercise in the one hour period immediately following exercise cessation. We employed transcranial Doppler (TCD) ultrasonography to measure cerebral blood flow velocity (CBFV) in the middle cerebral artery (MCAv) and posterior cerebral artery (PCAv) before, during, and following exercise. Additionally, we simultaneously measured cerebral blood flow (CBF) in the internal carotid artery (ICA) and vertebral artery (VA) before and up to one hour following exercise cessation using Duplex ultrasound. A hypercapnia challenge was used before and after exercise to examine exercise-induced changes in cerebrovascular reactivity (CVR). We found that MCAv and PCAv were significantly elevated during exercise (p = 4.81 × 10-5 and 2.40 × 10-4, respectively). A general linear model revealed that these changes were largely explained by the partial pressure of end-tidal CO2 and not a direct vascular effect of exercise. After exercise cessation, there was no effect of exercise on CBFV or CVR in the intracranial or extracranial arteries (all p > 0.05). Taken together, these data confirm that CBF is rapidly and uniformly regulated following exercise cessation in healthy young males.
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Affiliation(s)
- Jessica J Steventon
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, United Kingdom.,Cardiff University Brain Research Imaging Centre, School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Alex B Hansen
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Joseph R Whittaker
- Cardiff University Brain Research Imaging Centre, School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Kevin W Wildfong
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Daniela Nowak-Flück
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Michael M Tymko
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Kevin Murphy
- Cardiff University Brain Research Imaging Centre, School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Phil N Ainslie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Science, University of British Columbia Okanagan, Kelowna, BC, Canada
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24
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Ward JL, Craig JC, Liu Y, Vidoni ED, Maletsky R, Poole DC, Billinger SA. Effect of healthy aging and sex on middle cerebral artery blood velocity dynamics during moderate-intensity exercise. Am J Physiol Heart Circ Physiol 2018; 315:H492-H501. [PMID: 29775407 PMCID: PMC6172645 DOI: 10.1152/ajpheart.00129.2018] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Blood velocity measured in the middle cerebral artery (MCAV) increases with finite kinetics during moderate-intensity exercise, and the amplitude and dynamics of the response provide invaluable insights into the controlling mechanisms. The MCAV response after exercise onset is well fit to an exponential model in young individuals but remains to be characterized in their older counterparts. The responsiveness of vasomotor control degrades with advancing age, especially in skeletal muscle. We tested the hypothesis that older subjects would evince a slower and reduced MCAV response to exercise. Twenty-nine healthy young (25 ± 1 yr old) and older (69 ± 1 yr old) adults each performed a rapid transition from rest to moderate-intensity exercise on a recumbent stepper. Resting MCAV was lower in older than young subjects (47 ± 2 vs. 64 ± 3 cm/s, P < 0.001), and amplitude from rest to steady-state exercise was lower in older than young subjects (12 ± 2 vs. 18 ± 3 cm/s, P = 0.04), even after subjects were matched for work rate. As hypothesized, the time constant was significantly longer (slower) in the older than young subjects (51 ± 10 vs. 31 ± 4 s, P = 0.03), driven primarily by older women. Neither age-related differences in fitness, end-tidal CO2, nor blood pressure could account for this effect. Thus, MCAV kinetic analyses revealed a marked impairment in the cerebrovascular response to exercise in older individuals. Kinetic analysis offers a novel approach to evaluate the efficacy of therapeutic interventions for improving cerebrovascular function in elderly and patient populations. NEW & NOTEWORTHY Understanding the dynamic cerebrovascular response to exercise has provided insights into sex-related cerebrovascular control mechanisms throughout the aging process. We report novel differences in the kinetics response of cerebrovascular blood velocity after the onset of moderate-intensity exercise. The exponential increase in brain blood flow from rest to exercise revealed that 1) the kinetics profile of the older group was blunted compared with their young counterparts and 2) the older women demonstrated a slowed response.
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Affiliation(s)
- Jaimie L Ward
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center , Kansas City, Kansas
| | - Jesse C Craig
- Department of Kinesiology and Department of Anatomy and Physiology, Kansas State University , Manhattan, Kansas
| | - Yumei Liu
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center , Kansas City, Kansas
| | - Eric D Vidoni
- University of Kansas Alzheimer's Disease Center, Fairway, Kansas
| | | | - David C Poole
- Department of Kinesiology and Department of Anatomy and Physiology, Kansas State University , Manhattan, Kansas
| | - Sandra A Billinger
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center , Kansas City, Kansas
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25
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Evaluating the methods used for measuring cerebral blood flow at rest and during exercise in humans. Eur J Appl Physiol 2018; 118:1527-1538. [DOI: 10.1007/s00421-018-3887-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/09/2018] [Indexed: 10/16/2022]
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26
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Brugniaux JV, Coombs GB, Barak OF, Dujic Z, Sekhon MS, Ainslie PN. Highs and lows of hyperoxia: physiological, performance, and clinical aspects. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1-R27. [PMID: 29488785 DOI: 10.1152/ajpregu.00165.2017] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Molecular oxygen (O2) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content ([Formula: see text]), it also causes vasoconstriction and hence reduces O2 delivery in various vascular beds, including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e.g., brain ischemia, traumatic brain injury, carbon monoxide poisoning, etc.) and chronic hypoxemia (e.g., severe COPD, etc.) and to help with wound healing, necrosis, or reperfusion injuries (e.g., compromised grafts). Hyperoxia has also been used liberally by athletes in a belief that it offers performance-enhancing benefits; such benefits also extend to hypoxemic patients both at rest and during rehabilitation. This review aims to provide a comprehensive overview of the effects of hyperoxia in humans from the "bench to bedside." The first section will focus on the basic physiological principles of partial pressure of arterial O2, [Formula: see text], and barometric pressure and how these changes lead to variation in regional O2 delivery. This review provides an overview of the evidence for and against the use of hyperoxia as an aid to enhance physical performance. The final section addresses pathophysiological concepts, clinical studies, and implications for therapy. The potential of O2 toxicity and future research directions are also considered.
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Affiliation(s)
| | - Geoff B Coombs
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Faculty of Sport and Physical Education, University of Novi Sad, Novi Sad, Serbia
| | - Zeljko Dujic
- Department of Integrative Physiology, School of Medicine, University of Split , Split , Croatia
| | - Mypinder S Sekhon
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada.,Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia , Vancouver, British Columbia , Canada
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
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27
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Smith KJ, Ainslie PN. Regulation of cerebral blood flow and metabolism during exercise. Exp Physiol 2017; 102:1356-1371. [PMID: 28786150 DOI: 10.1113/ep086249] [Citation(s) in RCA: 191] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 07/31/2017] [Indexed: 12/18/2022]
Abstract
NEW FINDINGS What is the topic of this review? The manuscript collectively combines the experimental observations from >100 publications focusing on the regulation of cerebral blood flow and metabolism during exercise from 1945 to the present day. What advances does it highlight? This article highlights the importance of traditional and historical assessments of cerebral blood flow and metabolism during exercise, as well as traditional and new insights into the complex factors involved in the integrative regulation of brain blood flow and metabolism during exercise. The overarching theme is the importance of quantifying cerebral blood flow and metabolism during exercise using techniques that consider multiple volumetric cerebral haemodynamics (i.e. velocity, diameter, shear and flow). Cerebral function in humans is crucially dependent upon continuous oxygen delivery, metabolic nutrients and active regulation of cerebral blood flow (CBF). As a consequence, cerebrovascular function is precisely titrated by multiple physiological mechanisms, characterized by complex integration, synergism and protective redundancy. At rest, adequate CBF is regulated through reflexive responses in the following order of regulatory importance: fluctuating arterial blood gases (in particularly, partial pressure of carbon dioxide), cerebral metabolism, arterial blood pressure, neurogenic activity and cardiac output. Unfortunately, the magnitude that these integrative and synergistic relationships contribute to governing the CBF during exercise remains unclear. Despite some evidence indicating that CBF regulation during exercise is dependent on the changes of blood pressure, neurogenic activity and cardiac output, their role as a primary governor of the CBF response to exercise remains controversial. In contrast, the balance between the partial pressure of carbon dioxide and cerebral metabolism continues to gain empirical support as the primary contributor to the intensity-dependent changes in CBF observed during submaximal, moderate and maximal exercise. The goal of this review is to summarize the fundamental physiology and mechanisms involved in regulation of CBF and metabolism during exercise. The clinical implications of a better understanding of CBF during exercise and new research directions are also outlined.
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Affiliation(s)
- Kurt J Smith
- Cardiovascular Research Group, School of Sports Science, Exercise and Health, University of Western Australia, Crawley, WA, Australia.,Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
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28
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Ellis LA, Ainslie PN, Armstrong VA, Morris LE, Simair RG, Sletten NR, Tallon CM, McManus AM. Anterior cerebral blood velocity and end-tidal CO 2 responses to exercise differ in children and adults. Am J Physiol Heart Circ Physiol 2017; 312:H1195-H1202. [PMID: 28389601 DOI: 10.1152/ajpheart.00034.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/24/2017] [Accepted: 03/28/2017] [Indexed: 11/22/2022]
Abstract
Little is known about the response of the cerebrovasculature to acute exercise in children and how these responses might differ with adults. Therefore, we compared changes in middle cerebral artery blood velocity (MCAVmean), end-tidal Pco2 ([Formula: see text]), blood pressure, and minute ventilation (V̇e) in response to incremental exercise between children and adults. Thirteen children [age: 9 ± 1 (SD) yr] and thirteen sex-matched adults (age: 25 ± 4 yr) completed a maximal exercise test, during which MCAVmean, [Formula: see text], and V̇e were measured continuously. These variables were measured at rest, at exercise intensities specific to individual ventilatory thresholds, and at maximum. Although MCAVmean was higher at rest in children compared with adults, there were smaller increases in children (1-12%) compared with adults (12-25%) at all exercise intensities. There were alterations in [Formula: see text] with exercise intensity in an age-dependent manner [F(2.5,54.5) = 7.983, P < 0.001; η2 = 0.266], remaining stable in children with increasing exercise intensity (37-39 mmHg; P > 0.05) until hyperventilation-induced reductions following the respiratory compensation point. In adults, [Formula: see text] increased with exercise intensity (36-45 mmHg, P < 0.05) until the ventilatory threshold. From the ventilatory threshold to maximum, adults showed a greater hyperventilation-induced hypocapnia than children. These findings show that the relative increase in MCAVmean during exercise was attenuated in children compared with adults. There was also a weaker relationship between MCAVmean and [Formula: see text] during exercise in children, suggesting that cerebral perfusion may be regulated by different mechanisms during exercise in the child.NEW & NOTEWORTHY These findings provide the first direct evidence that exercise increases cerebral blood flow in children to a lesser extent than in adults. Changes in end-tidal CO2 parallel changes in cerebral perfusion in adults but not in children, suggesting age-dependent regulatory mechanisms of cerebral blood flow during exercise.
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Affiliation(s)
- Lindsay A Ellis
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Victoria A Armstrong
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Laura E Morris
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Ryan G Simair
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Nathan R Sletten
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Christine M Tallon
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Ali M McManus
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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