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Dominelli PB, Sheel AW. The pulmonary physiology of exercise. Adv Physiol Educ 2024; 48:238-251. [PMID: 38205515 DOI: 10.1152/advan.00067.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 12/14/2023] [Accepted: 01/07/2024] [Indexed: 01/12/2024]
Abstract
The pulmonary system is the first and last "line of defense" in terms of maintaining blood gas homeostasis during exercise. Our review provides the reader with an overview of how the pulmonary system responds to acute exercise. We undertook this endeavor to provide a companion article to "Cardiovascular Response to Exercise," which was published in Advances in Physiological Education. Together, these articles provide the readers with a solid foundation of the cardiopulmonary response to acute exercise in healthy individuals. The intended audience of this review is level undergraduate or graduate students and/or instructors for such classes. By intention, we intend this to be used as an educational resource and seek to provide illustrative examples to reinforce topics as well as highlight uncertainty to encourage the reader to think "beyond the textbook." Our treatment of the topic presents "classic" concepts along with new information on the pulmonary physiology of healthy aging.NEW & NOTEWORTHY Our narrative review is written with the student of the pulmonary physiology of exercise in mind, be it a senior undergraduate or graduate student or those simply refreshing their knowledge. We also aim to provide examples where the reader can incorporate real scenarios.
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Affiliation(s)
- Paolo B Dominelli
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - A William Sheel
- School of Kinesiology, The University of British Columbia, Vancouver, British Columbia, Canada
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Thompson BP, Doherty CJ, Mann LM, Chang JC, Angus SA, Foster GE, Au JS, Dominelli PB. Supramaximal Testing to Confirm the Achievement of V̇O 2max in Acute Hypoxia. Med Sci Sports Exerc 2024; 56:673-681. [PMID: 37962226 DOI: 10.1249/mss.0000000000003339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
PURPOSE We sought to determine if supramaximal exercise testing confirms the achievement of V̇O 2max in acute hypoxia. We hypothesized that the incremental and supramaximal V̇O 2 will be sufficiently similar in acute hypoxia. METHODS Twenty-one healthy adults (males n = 13, females n = 8) completed incremental and supramaximal exercise tests in normoxia and acute hypoxia (fraction inspired oxygen = 0.14) separated by at least 48 h. Incremental exercise started at 80 and 60 W in normoxia and 40 and 20 W in hypoxia for males and females, respectively, with all increasing by 20 W each minute until volitional exhaustion. After a 20-min postexercise rest period, a supramaximal test at 110% peak power until volitional exhaustion was completed. RESULTS Supramaximal exercise testing yielded a lower V̇O 2 than incremental testing in hypoxia (3.11 ± 0.78 vs 3.21 ± 0.83 L·min -1 , P = 0.001) and normoxia (3.71 ± 0.91 vs 3.80 ± 1.02 L·min -1 , P = 0.01). Incremental and supramaximal V̇O 2 were statistically similar, using investigator-determined equivalence bounds ±150 mL·min -1 , in hypoxia ( P = 0.02, 90% confidence interval [CI] = 0.05-0.14) and normoxia ( P = 0.03, 90% CI = 0.01-0.14). Likewise, using ±2.1 mL·kg -1 ·min -1 bounds, incremental and supramaximal V̇O 2 values were statistically similar in hypoxia ( P = 0.04, 90% CI = 0.70-2.0) and normoxia ( P = 0.04, 90% CI = 0.30-2.0). CONCLUSIONS Despite differences in the oxygen cascade, incremental and supramaximal V̇O 2 values were statistically similar in both hypoxia and normoxia, demonstrating the utility of supramaximal verification of V̇O 2max in the setting of acute hypoxia.
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Affiliation(s)
- Benjamin P Thompson
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, CANADA
| | - Connor J Doherty
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, CANADA
| | - Leah M Mann
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, CANADA
| | - Jou-Chung Chang
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, CANADA
| | - Sarah A Angus
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, CANADA
| | - Glen E Foster
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, CANADA
| | - Jason S Au
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, CANADA
| | - Paolo B Dominelli
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, CANADA
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Mann LM, Chan JS, Angus SA, Doherty CJ, Thompson BP, Foster GE, Dominelli PB. Tidal expiratory flow limitation during exercise is unrelated to peripheral hypercapnic chemosensitivity. Respir Physiol Neurobiol 2024; 325:104254. [PMID: 38552704 DOI: 10.1016/j.resp.2024.104254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/23/2024] [Accepted: 03/24/2024] [Indexed: 04/12/2024]
Abstract
We sought to determine if peripheral hypercapnic chemosensitivity is related to expiratory flow limitation (EFL) during exercise. Twenty participants completed one testing day which consisted of peripheral hypercapnic chemosensitivity testing and a maximal exercise test to exhaustion. The chemosensitivity testing consisting of two breaths of 10% CO2 (O2∼21%) repeated 5 times during seated rest and the first 2 exercise intensities during the maximal exercise test. Following chemosensitivity testing, participants continued cycling with the intensity increasing 20 W every 1.5 minutes till exhaustion. Maximal expiratory flow-volume curves were derived from forced expiratory capacity maneuvers performed before and after exercise at varying efforts. Inspiratory capacity maneuvers were performed during each exercise stage to determine EFL. There was no difference between the EFL and non-EFL hypercapnic chemoresponse (mean response during exercise 0.96 ± 0.46 and 0.91 ± 0.33 l min-1 mmHg-1, p=0.783). Peripheral hypercapnic chemosensitivity during mild exercise does not appear to be related to the development of EFL during exercise.
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Affiliation(s)
- Leah M Mann
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
| | - Jason S Chan
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Sarah A Angus
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Connor J Doherty
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Benjamin P Thompson
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Glen E Foster
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC V1V 1V7, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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Molgat-Seon Y, Sawatzky MAT, Dominelli PB, Kirby M, Guenette JA, Bourbeau J, Tan WC, Sheel AW. Dysanapsis is not associated with exertional dyspnoea in healthy male and female never-smokers aged 40 years and older. Appl Physiol Nutr Metab 2024; 49:223-235. [PMID: 37847929 DOI: 10.1139/apnm-2023-0246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
In healthy adults, airway-to-lung (i.e., dysanapsis) ratio is lower and dyspnoea during exercise at a given minute ventilation (V̇E) is higher in females than in males. We investigated the relationship between dysanapsis and sex on exertional dyspnoea in healthy adults. We hypothesized that females would have a smaller airway-to-lung ratio than males and that exertional dyspnoea would be associated with airway-to-lung ratio in males and females. We analyzed data from n = 100 healthy never-smokers aged ≥40 years enrolled in the Canadian Cohort Obstructive Lung Disease (CanCOLD) study who underwent pulmonary function testing, a chest computed tomography scan, and cardiopulmonary exercise testing. The luminal area of the trachea, right main bronchus, left main bronchus, right upper lobe, bronchus intermedius, left upper lobe, and left lower lobe were 22%-37% smaller (all p < 0.001) and the airway-to-lung ratio (i.e., average large conducting airway diameter relative to total lung capacity) was lower in females than in males (0.609 ± 0.070 vs. 0.674 ± 0.082; p < 0.001). During exercise, there was a significant effect of V̇E, sex, and their interaction on dyspnoea (all p < 0.05), indicating that dyspnoea increased as a function of V̇E to a greater extent in females than in males. However, after adjusting for age and total lung capacity, there were no significant associations between airway-to-lung ratio and measures of exertional dyspnoea, regardless of sex (all r < 0.34; all p > 0.05). Our findings suggest that sex differences in airway size do not contribute to sex differences in exertional dyspnoea.
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Affiliation(s)
- Yannick Molgat-Seon
- Department of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
- Centre for Heart and Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, BC V6Z 1Y6, Canada
| | - Mathieu A T Sawatzky
- Department of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - Paolo B Dominelli
- Department of KinesiologyUniversity of Waterloo, Waterloo, ON N2 L3G1, Canada
| | - Miranda Kirby
- Department of PhysicsToronto Metropolitan University, Toronto, ON M5 B2K3, Canada
| | - Jordan A Guenette
- Centre for Heart and Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, BC V6Z 1Y6, Canada
- Department of Physical TherapyThe University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- School of Kinesiology, The University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jean Bourbeau
- Department of MedicineMcGill University, Montreal, QC H4A 3J1, Canada
| | - Wan C Tan
- Centre for Heart and Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, BC V6Z 1Y6, Canada
| | - A William Sheel
- Centre for Heart and Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, BC V6Z 1Y6, Canada
- School of Kinesiology, The University of British Columbia, Vancouver, BC V6T 1Z1, Canada
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Wright MD, Mann LM, Doherty CJ, Thompson BP, Angus SA, Chang JC, Dominelli PB. Peripheral hypercapnic chemosensitivity at rest and progressive exercise intensities in males and females. J Appl Physiol (1985) 2024; 136:274-282. [PMID: 38126093 DOI: 10.1152/japplphysiol.00578.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/04/2023] [Accepted: 12/13/2023] [Indexed: 12/23/2023] Open
Abstract
Peripheral hypercapnic chemosensitivity (PHC) is the ventilatory response to hypercapnia and is enhanced with acute whole body exercise. However, little is known about the mechanism(s) responsible for the exercise-related increase in PHC and if progressive exercise leads to further augmentation. We hypothesized that unloaded cycle exercise (0 W) would increase PHC but progressively increasing the intensity would not further augment the response. Twenty healthy subjects completed two testing days. Day 1 was a maximal exercise test on a cycle ergometer to determine peak power output (Wmax). Day 2 consisted of six 12-min stages: 1) rest on chair, 2) rest on bike, 3) 0 W unloaded cycling, 4) 25% Wmax, 5) 50% Wmax, and 6) ∼70% Wmax with ∼10 min of rest between each exercise stage. In each stage, PHC was assessed via two breaths of 10% CO2 (∼21% O2) repeated five times with ∼45 s between each to ensure end-tidal CO2 ([Formula: see text]) and ventilation returned to baseline. Prestimulus [Formula: see text] was not different between rest and unloaded cycling (P = 0.478). There was a significant increase in PHC between seated rest and 25% Wmax (0.71 ± 0.37 vs. 1.03 ± 0.52 L·mmHg-1·min-1, respectively, P = 0.0006) and between seated rest and unloaded cycling (0.71 ± 0.37 vs. 1.04 ± 0.4 L·mmHg-1·min-1, respectively, P = 0.0017). There was no effect of exercise intensity on PHC (1.03 ± 0.52 vs. 0.95 ± 0.58 vs. 1.01 ± 0.65 L·mmHg-1·min-1 for 25, 50, and 70% Wmax, P = 0.44). The increased PHC response from seated rest to unloaded and 25% Wmax, but no effect of exercise intensity suggests a possible feedforward/feedback mechanism causing increased PHC sensitivity through the act of cycling.NEW & NOTEWORTHY Unloaded exercise significantly increased the peripheral hypercapnic ventilatory response (HCVR) compared with rest. However, increases in exercise intensity did not further augment peripheral HCVR. Males had a greater peripheral HCVR compared with females, but there was no interaction between sex and intensity. The lack of sex interactions suggests the mechanism augmenting the peripheral HCVR with exercise is independent of sex. The increase in peripheral HCVR with exercise is likely due to central command.
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Affiliation(s)
- Madeline D Wright
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Leah M Mann
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Connor J Doherty
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin P Thompson
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Sarah A Angus
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Jou-Chung Chang
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Paolo B Dominelli
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
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Dominelli PB, Senefeld JW, Wiggins CC, Baker SE, Clayburn AJ, Joyner MJ. Quadriceps fatigue during hypoxic and ischemic knee-extension exercise is similar in males and females. J Appl Physiol (1985) 2024; 136:177-188. [PMID: 38059290 DOI: 10.1152/japplphysiol.00656.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 11/29/2023] [Accepted: 12/04/2023] [Indexed: 12/08/2023] Open
Abstract
Hypoxia is known to increase muscle fatigue via both central and peripheral mechanisms. Females are typically less fatigable than males during isometric fatiguing contractions due to greater peripheral blood flow. However, sex differences in fatigue are blunted during dynamic fatiguing tasks. Thus, this study determined the interactions of sex and hypoxia on knee extensor muscle contractile function during a dynamic, ischemic fatiguing contraction. Electrical stimulation was used to determine contractile properties of the knee extensor muscles in eight males and eight females before and after an ischemic, dynamic fatiguing task while inspiring room air or a hypoxic gas mixture (10% O2:90% N2). Fatigue (assessed as time-to-task failure) was ∼10% greater during the hypoxic condition (94.3 ± 33.4 s) compared with normoxic condition (107.0 ± 42.8 s, P = 0.041) and ∼40% greater for females than males (77.1 ± 18.8 vs. 124.2 ± 38.7, P < 0.001). Immediately after the dynamic fatiguing task, there were reductions in maximal voluntary contraction force (P = 0.034) and electrically evoked twitch force (P < 0.001), and these reductions did not differ based on sex or inspirate. Cerebral tissue oxygenation showed a significant interaction of time and inspirate (P = 0.003) whereby it increased during normoxia and remained unchanged in hypoxia. No sex-related differences in the changes of cerebral tissue oxygenation were observed (P = 0.528). These data suggest that acute hypoxia increases central fatigue during ischemic single-leg exercise resulting in earlier exercise termination, but the effect does not differ based on sex.NEW & NOTEWORTHY Hypoxia exacerbates fatigue via central mechanisms after ischemic single-leg exercise. The greater fatigue observed during ischemic dynamic fatiguing exercise with hypoxia inspirate did not differ between the sexes. Hypoxia-induced central limitations are present in acute ischemic exercise and do not appear different in males and females.
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Affiliation(s)
- Paolo B Dominelli
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Jonathon W Senefeld
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
- Department of Kinesiology, Michigan State University, East Lansing, Michigan, United States
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Andrew J Clayburn
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
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Angus SA, Taylor JL, Mann LM, Williams AM, Stöhr EJ, Au JS, Sheel AW, Dominelli PB. Attenuating intrathoracic pressure swings decreases cardiac output at different intensities of exercise. J Physiol 2023; 601:4807-4821. [PMID: 37772933 DOI: 10.1113/jp285101] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 09/05/2023] [Indexed: 09/30/2023] Open
Abstract
Intrathoracic pressure (ITP) swings that permit spontaneous ventilation have physiological implications for the heart. We sought to determine the effect of respiration on cardiac output (Q ̇ $\dot Q$ ) during semi-supine cycle exercise using a proportional assist ventilator to minimize ITP changes and lower the work of breathing (Wb ). Twenty-four participants (12 females) completed three exercise trials at 30%, 60% and 80% peak power (Wmax ) with unloaded (using a proportional assist ventilator, PAV) and spontaneous breathing. Intrathoracic and intraabdominal pressures were measured with balloon catheters placed in the oesophagus and stomach. Left ventricular (LV) volumes andQ ̇ $\dot Q$ were determined via echocardiography. Heart rate (HR) was measured with electrocardiogram and a customized metabolic cart measured oxygen uptake (V ̇ O 2 ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}}}$ ). Oesophageal pressure swings decreased from spontaneous to PAV breathing by -2.8 ± 3.1, -4.9 ± 5.7 and -8.1 ± 7.7 cmH2 O at 30%, 60% and 80% Wmax , respectively (P = 0.01). However, the decreases in Wb were similar across exercise intensities (27 ± 42 vs. 35 ± 24 vs. 41 ± 22%, respectively, P = 0.156). During PAV breathing compared to spontaneous breathing,Q ̇ $\dot Q$ decreased by -1.0 ± 1.3 vs. -1.4 ± 1.4 vs. -1.5 ± 1.9 l min-1 (all P < 0.05) and stroke volume decreased during PAV breathing by -11 ± 12 vs. -9 ± 10 vs. -7 ± 11 ml from spontaneous breathing at 30%, 60% and 80% Wmax , respectively (all P < 0.05). HR was lower during PAV breathing by -5 ± 4 beats min-1 at 80% Wmax (P < 0.0001). Oxygen uptake decreased by 100 ml min-1 during PAV breathing compared to spontaneous breathing at 80% Wmax (P < 0.0001). Overall, attenuating ITPs mitigated LV preload and ejection, thereby suggesting that the ITPs associated with spontaneous respiration impact cardiac function during exercise. KEY POINTS: Pulmonary ventilation is accomplished by alterations in intrathoracic pressure (ITP), which have physiological implications on the heart and dynamically influence the loading parameters of the heart. Proportional assist ventilation was used to attenuate ITP changes and decrease the work of breathing during exercise to examine its effects on left ventricular (LV) function. Proportional assist ventilation with progressive exercise intensities (30%, 60% and 80% Wmax ) led to reductions in cardiac output at all intensities, primarily through reductions in stroke volume. Decreases in LV end-diastolic volume (30% and 60% Wmax ) and increases in LV end-systolic volume (80% Wmax ) were responsible for the reduction in stroke volume. The relationship between cardiac output and oxygen uptake is disrupted during respiratory muscle unloading.
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Affiliation(s)
- Sarah A Angus
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Joshua L Taylor
- School of Kinesiology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Leah M Mann
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Alexandra M Williams
- International Collaboration on Repair Discoveries (ICORD), The University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Science, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Eric J Stöhr
- Institute of Sports Science, COR-HELIX, Leibniz University Hannover, Hannover, Germany
- Department of Medicine, Division of Cardiology, Columbia University Irving Medical Center, New York, NY, USA
| | - Jason S Au
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Andrew William Sheel
- School of Kinesiology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Paolo B Dominelli
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
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Ramsook AH, Dominelli PB, Angus SA, Senefeld JW, Wiggins CC, Joyner MJ. The oxygen transport cascade and exercise: Lessons from comparative physiology. Comp Biochem Physiol A Mol Integr Physiol 2023; 282:111442. [PMID: 37182787 DOI: 10.1016/j.cbpa.2023.111442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/09/2023] [Accepted: 05/11/2023] [Indexed: 05/16/2023]
Abstract
Studies of animal physiology not only provide valuable knowledge for the species in question, but also offer insights into human physiology. This thought is best highlighted by the 'Krogh Principle', which states "for many problems there is an animal on which it can be most conveniently studied". This graphical review focuses on three distinct stages of the oxygen transport cascade in which human exercise physiology knowledge has been enhanced by studies carried out in animal models. We begin by exploring ventilation, and the detrimental effects of cold, dry air on the airways in two sets of elite athletes, the cross-country skier and the racing sled dog. We then discuss the transport of oxygen via hemoglobin and the shifts in humans and deer mice with relatively shifted oxygen dissociation curves. Finally, we consider the technical difficulties of measuring respiratory muscle blood flow in exercising humans and how an equine model can provide an understanding of the distribution of blood flow during exercise. These cases illustrate the complementary nature of physiological studies across species.
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Affiliation(s)
- Andrew H Ramsook
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, USA
| | - Paolo B Dominelli
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Sarah A Angus
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Jonathon W Senefeld
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, USA; Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Chad C Wiggins
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, USA; Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Michael J Joyner
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, USA; Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.
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Pruter WW, Klassen SA, Dominelli PB, Wiggins CC, Senefeld JW, Roy TK, Joyner MJ, Baker SE. Attenuated cardiac autonomic function in humans with high-affinity hemoglobin and compensatory polycythemia. Am J Physiol Regul Integr Comp Physiol 2023; 324:R625-R634. [PMID: 36878486 PMCID: PMC10085552 DOI: 10.1152/ajpregu.00113.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 02/28/2023] [Accepted: 03/01/2023] [Indexed: 03/08/2023]
Abstract
During hypoxic exposure, humans with high-affinity hemoglobin (and compensatory polycythemia) have blunted increases in heart rate compared with healthy humans with typical oxyhemoglobin dissociation curves. This response may be associated with altered autonomic control of heart rate. Our hypothesis-generating study aimed to investigate cardiac baroreflex sensitivity and heart rate variability among nine humans with high-affinity hemoglobin [6 females, O2 partial pressure at 50% [Formula: see text] (P50) = 16 ± 1 mmHg] compared with 12 humans with typical affinity hemoglobin (6 F, P50 = 26 ± 1 mmHg). Participants breathed normal room air for a 10-min baseline, followed by 20 min of isocapnic hypoxic exposure, designed to lower the arterial partial pressure O2 ([Formula: see text]) to ∼50 mmHg. Beat-by-beat heart rate and arterial blood pressure were recorded. Data were averaged in 5-min periods throughout the hypoxia exposure, beginning with the last 5 min of baseline in normoxia. Spontaneous cardiac baroreflex sensitivity and heart rate variability were determined using the sequence method and the time and frequency domain analyses, respectively. Cardiac baroreflex sensitivity was lower in humans with high-affinity hemoglobin than controls at baseline and during isocapnic hypoxic exposure (normoxia: 7 ± 4 vs. 16 ± 10 ms/mmHg, hypoxia minutes 15-20: 4 ± 3 vs. 14 ± 11 ms/mmHg; group effect: P = 0.02, high-affinity hemoglobin vs. control, respectively). Heart rate variability calculated in both the time (standard deviation of the N-N interval) and frequency (low frequency) domains was lower in humans with high-affinity hemoglobin than in controls (all P < 0.05). Our data suggest that humans with high-affinity hemoglobin may have attenuated cardiac autonomic function.
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Affiliation(s)
- Wyatt W Pruter
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Stephen A Klassen
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Jonathon W Senefeld
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Tuhin K Roy
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
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Chan JS, Mann LM, Doherty CJ, Angus SA, Thompson BP, Devries MC, Hughson RL, Dominelli PB. The effect of inspiratory muscle training and detraining on the respiratory metaboreflex. Exp Physiol 2023; 108:636-649. [PMID: 36754374 PMCID: PMC10103864 DOI: 10.1113/ep090779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 12/13/2022] [Indexed: 02/10/2023]
Abstract
NEW FINDINGS What is the central question of this study? Is the attenuation of the respiratory muscle metaboreflex preserved after detraining? What is the main finding and its importance? Inspiratory muscle training increased respiratory muscle strength and attenuated the respiratory muscle metaboreflex as evident by lower heart rate and blood pressure. After 5 weeks of no inspiratory muscle training (detraining), respiratory muscle strength was still elevated and the metaboreflex was still attenuated. The benefits of inspiratory muscle training persist after cessation of training, and attenuation of the respiratory metaboreflex follows changes in respiratory muscle strength. ABSTRACT Respiratory muscle training (RMT) improves respiratory muscle (RM) strength and attenuates the RM metaboreflex. However, the time course of muscle function loss after the absence of training or 'detraining' is less known and some evidence suggest the respiratory muscles atrophy faster than other muscles. We sought to determine the RM metaboreflex in response to 5 weeks of RMT and 5 weeks of detraining. An experimental group (2F, 6M; 26 ± 4years) completed 5 weeks of RMT and tibialis anterior (TA) training (each 5 days/week at 50% of maximal inspiratory pressure (MIP) and 50% maximal isometric force, respectively) followed by 5 weeks of no training (detraining) while a control group (1F, 7M; 24 ± 1years) underwent no intervention. Prior to training (PRE), post-training (POST) and post-detraining (DETR), all participants underwent a loaded breathing task (LBT) to failure (60% MIP) while heart rate and mean arterial blood pressure (MAP) were measured. Five weeks of training increased RM (18 ± 9%, P < 0.001) and TA (+34 ± 19%, P < 0.001) strength and both remained elevated after 5 weeks of detraining (MIP-POST vs. MIP-DETR: 154 ± 31 vs. 153 ± 28 cmH2O, respectively, P = 0.853; TA-POST vs. TA-DETR: 86 ± 19 vs. 85 ± 16 N, respectively, P = 0.982). However, the rise in MAP during LBT was attenuated POST (-11 ± 17%, P = 0.003) and DETR (-9 ± 9%, P = 0.007) during the iso-time LBT. The control group had no change in MIP (P = 0.33), TA strength (P = 0.385), or iso-time MAP (P = 0.867) during LBT across all time points. In conclusion, RM and TA have similar temporal strength gains and the attenuation of the respiratory muscle metaboreflex remains after 5 weeks of detraining.
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Affiliation(s)
- Jason S. Chan
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
| | - Leah M. Mann
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
| | - Connor J. Doherty
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
| | - Sarah A. Angus
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
| | - Benjamin P. Thompson
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
| | - Michaela C. Devries
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
| | - Richard L. Hughson
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
- Schlegel‐UW Research Institute for AgingWaterlooOntarioCanada
| | - Paolo B. Dominelli
- Department of Kinesiology and Health SciencesFaculty of HealthUniversity of WaterlooWaterlooOntarioCanada
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11
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Chang JC, Angus SA, Doherty C, Thompson BP, Mann L, Molgat-Seon Y, Dominelli PB. Perception of exercise-induced dyspnea after experimentally induced breathing discomfort. Appl Physiol Nutr Metab 2023. [PMID: 36957991 DOI: 10.1139/apnm-2022-0362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
The perception of dyspnea is influenced by both physiological and psychological factors. We sought to determine if exertional dyspnea perception could be experimentally manipulated through prior exposure to heightened dyspnea while exercising. We hypothesized that dyspnea perception during exercise would be lower following an induced dyspnea task (IDT). Sixteen healthy participants (8 females, 8 males) completed two days of exercise testing. Day 1 involved an incremental cycle exercise test starting at 40W for females and 60W for males, increasing by 20W each minute until volitional exhaustion. Following the maximal exercise test on Day 1, participants completed IDT, involving 5-mins of exercise at 70% of peak workrate with 500 mL dead space and external resistance (i.e., 6.8±2.3cmH2O·s-1·L-1 inspiration, 3.8±0.7cmH2O·s-1·L-1 expiration). Day 2 consisted of an incremental exercise test identical to Day 1. At maximal exercise, there were no differences in oxygen uptake (V̇O2; 44.7±7.7 vs 46.5±6.3 mL·kg-1·min-1), minute ventilation (120±35 vs 127±38 L·min-1), dyspnea (6.5 [4,8.5] vs 6[4.25,8.75]) or leg discomfort (6 [5,8.75] vs 7 [5,9]) between days (all p>0.05). At 60-80% of peak V̇O2 (V̇O2peak), dyspnea was significantly lower on Day 2 (-0.75[-1.375,0] for 60, and -0.5[0,-2] for 80%, p<0.05) despite no differences in relevant physiological variables. The onset of perceived dyspnea occurred at a significantly higher exercise intensity on Day 2 than on Day 1 (42±19 vs 51±17%V̇O2peak, respectively; p<0.05). Except for 40% V̇O2peak (p=0.05), RPE-L was not different at any intensities nor was the onset of perceived leg discomfort different between days (38±14 vs 43±10 % V̇O2peak, respectively; p=0.10). Exposure to heightened dyspnea alters exercise-induced dyspnea perception during subsequent submaximal exercise bouts.
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Affiliation(s)
- Jou-Chung Chang
- University of Waterloo, 8430, Department of Kinesiology and Health Sciences, Waterloo, Canada;
| | - Sarah Anne Angus
- University of Waterloo, 8430, Department of Kinesiology, Waterloo, Ontario, Canada;
| | - Connor Doherty
- University of Waterloo, 8430, Department of Kinesiology, Waterloo, Ontario, Canada;
| | - Benjamin P Thompson
- University of Waterloo, 8430, Department of Kinesiology and Health Sciences, Waterloo, Canada;
| | - Leah Mann
- University of Waterloo, 8430, Department of Kinesiology, Waterloo, Ontario, Canada;
| | - Yannick Molgat-Seon
- University of Winnipeg, 8665, Kinesiology & Applied Health, Winnipeg, Manitoba, Canada;
| | - Paolo B Dominelli
- University of Waterloo, 8430, Department of Kinesiology and Health Sciences, Waterloo, Canada;
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12
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Angus SA, Chang JC, Mann LM, Thompson BP, Doherty CJ, Dominelli PB. Altering magnetic field strength impacts the assessment of diaphragmatic function using cervical magnetic stimulation. Respir Physiol Neurobiol 2023; 309:104012. [PMID: 36592844 DOI: 10.1016/j.resp.2022.104012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/20/2022] [Accepted: 12/28/2022] [Indexed: 12/31/2022]
Abstract
Quantifying diaphragm neuromuscular function using cervical magnetic stimulation (CMS) typically uses only a single stimulator (1-Stim) which may be inadequate to maximally stimulate the phrenic nerves. We questioned if using two stimulators (2-Stim) together alters diaphragm neuromuscular function at baseline and following inspiratory pressure threshold loading. Six (n = 3 female) healthy young participants were instrumented with esophageal and gastric balloon tipped catheters and electrodes over the 7-8th intercostal space. With either 1-Stim or 2-Stim an incremental protocol, where the stimulator intensity was progressively increased was completed prior to a series of potentiated twitches. The inspiratory threshold loading test consisted of loaded breathing to failure. Compared to 1-Stim, 2-Stim resulted in significantly greater unpotentiated Pditw and M-waves during the incremental protocol (both p < 0.01). Similarly, 2-Stim resulted in greater potentiated Pditw (31 ± 8 vs. 41 ± 9 cmH2O; p = 0.02) and M-waves (6.4 ± 2.9 vs. 8.6 ± 2.4 V; p = 0.02). Our findings suggest that CMS using 1-Stim is unlikely to generate a sufficient magnetic field to maximally stimulate the phrenic nerves and may underestimate diaphragm function.
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Affiliation(s)
- Sarah A Angus
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, Canada
| | - Jou-Chung Chang
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, Canada
| | - Leah M Mann
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, Canada
| | - Benjamin P Thompson
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, Canada
| | - Connor J Doherty
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, Canada
| | - Paolo B Dominelli
- Department of Kinesiology and Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, Canada.
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13
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Ferguson ON, Mitchell RA, Schaeffer MR, Ramsook AH, Dhillon SS, Dominelli PB, Molgat-Seon Y, Guenette JA. Effects of Face Masks on the Multiple Dimensions and Neurophysiological Mechanisms of Exertional Dyspnea. Med Sci Sports Exerc 2023; 55:450-461. [PMID: 36469484 DOI: 10.1249/mss.0000000000003074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
INTRODUCTION During the coronavirus disease 2019 pandemic, public health officials widely adopted the use of face masks (FM) to minimize infections. Despite consistent evidence that FMs increase dyspnea, no studies have examined the multidimensional components of dyspnea or their underlying physiological mechanisms. METHODS In a randomized crossover design, 16 healthy individuals ( n = 9 women, 25 ± 3 yr) completed incremental cycling tests over three visits, where visits 2 and 3 were randomized to either surgical FM or no mask control. Dyspnea intensity and unpleasantness were assessed throughout exercise (0-10 Borg scale), and the Multidimensional Dyspnea Profile was administered immediately after exercise. Crural diaphragmatic EMG and esophageal pressure were measured using a catheter to estimate neural respiratory drive and respiratory muscle effort, respectively. RESULTS Dyspnea unpleasantness was significantly greater with the FM at the highest equivalent submaximal work rate achieved by a given participant in both conditions (iso-work; 5.9 ± 1.7 vs 3.9 ± 2.9 Borg 0-10 units, P = 0.007) and at peak exercise (7.8 ± 2.1 vs 5.9 ± 3.4 Borg 0-10 units, P = 0.01) with no differences in dyspnea intensity ratings throughout exercise compared with control. There were significant increases in the sensory quality of "smothering/air hunger" ( P = 0.01) and the emotional response of "anxiousness" ( P = 0.04) in the FM condition. There were significant increases in diaphragmatic EMG and esophageal pressure at select submaximal work rates, but no differences in heart rate, pulse oximetry-derived arterial oxygen saturation, or breathing frequency throughout exercise with FMs compared with control. FMs significantly reduced peak work rate and exercise duration (both P = 0.02). CONCLUSIONS FMs negatively impact the affective domain of dyspnea and increase neural respiratory drive and respiratory muscle effort during exercise, although the impact on other cardiorespiratory responses are minimal.
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Affiliation(s)
| | | | | | | | - Satvir S Dhillon
- Centre for Heart Lung Innovation, Providence Research, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, CANADA
| | - Paolo B Dominelli
- Department of Kinesiology, Faculty of Health, University of Waterloo, Waterloo, Ontario, CANADA
| | - Yannick Molgat-Seon
- Faculty of Kinesiology and Applied Health, The University of Winnipeg, Winnipeg, Manitoba, CANADA
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14
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Doherty CJ, Chang JC, Thompson BP, Swenson ER, Foster GE, Dominelli PB. The Impact of Acetazolamide and Methazolamide on Exercise Performance in Normoxia and Hypoxia. High Alt Med Biol 2023; 24:7-18. [PMID: 36802203 DOI: 10.1089/ham.2022.0134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Doherty, Connor J., Jou-Chung Chang, Benjamin P. Thompson, Erik R. Swenson, Glen E. Foster, and Paolo B. Dominelli. The impact of acetazolamide and methazolamide on exercise performance in normoxia and hypoxia. High Alt Med Biol. 24:7-18, 2023.-Carbonic anhydrase (CA) inhibitors are commonly prescribed for acute mountain sickness (AMS). In this review, we sought to examine how two CA inhibitors, acetazolamide (AZ) and methazolamide (MZ), affect exercise performance in normoxia and hypoxia. First, we briefly describe the role of CA inhibition in facilitating the increase in ventilation and arterial oxygenation in preventing and treating AMS. Next, we detail how AZ affects exercise performance in normoxia and hypoxia and this is followed by a discussion on MZ. We emphasize that the overarching focus of the review is how the two drugs potentially affect exercise performance, rather than their ability to prevent/treat AMS per se, their interrelationship will be discussed. Overall, we suggest that AZ hinders exercise performance in normoxia, but may be beneficial in hypoxia. Based upon head-to-head studies of AZ and MZ in humans on diaphragmatic and locomotor strength in normoxia, MZ may be a better CA inhibitor when exercise performance is crucial at high altitude.
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Affiliation(s)
- Connor J Doherty
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Jou-Chung Chang
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin P Thompson
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Erik R Swenson
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Washington, USA
- Medical Service, VA Puget Sound Health Care System, Seattle, Washington, USA
| | - Glen E Foster
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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15
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Gerson EAM, Dominelli PB, Leahy MG, Kipp S, Guenette JA, Archiza B, Sheel AW. The effect of proportional assist ventilation on the electrical activity of the human diaphragm during exercise. Exp Physiol 2023; 108:296-306. [PMID: 36420595 PMCID: PMC10103863 DOI: 10.1113/ep090808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/10/2022] [Indexed: 11/25/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the effect of lowering the normally occurring work of breathing on the electrical activity and pressure generated by the diaphragm during submaximal exercise in healthy humans? What is the main finding and its importance? Ventilatory assist during exercise elicits a proportional lowering of both the work performed by the diaphragm and diaphragm electrical activity. These findings have implications for exercise training studies using proportional assist ventilation to reduce diaphragm work in patients with cardiopulmonary disease. ABSTRACT We hypothesized that when a proportional assist ventilator (PAV) is applied in order to reduce the pressure generated by the diaphragm, there would be a corresponding reduction in electrical activity of the diaphragm. Healthy participants (five male and four female) completed an incremental cycle exercise test to exhaustion in order to calculate workloads for subsequent trials. On the experimental day, participants performed submaximal cycling, and three levels of assisted ventilation were applied (low, medium and high). Ventilatory parameters, pulmonary pressures and EMG of the diaphragm (EMGdi ) were obtained. To compare the PAV conditions with spontaneous breathing intervals, ANOVA procedures were used, and significant effects were evaluated with a Tukey-Kramer test. Significance was set at P < 0.05. The work of breathing was not different between the lowest level of unloading and spontaneous breathing (P = 0.151) but was significantly lower during medium (25%, P = 0.02) and high (36%, P < 0.001) levels of PAV. The pressure-time product of the diaphragm (PTPdi ) was lower across PAV unloading conditions (P < 0.05). The EMGdi was significantly lower in medium and high PAV conditions (P = 0.035 and P < 0.001, respectively). The mean reductions of EMGdi with PAV unloading were 14, 22 and 39%, respectively. The change in EMGdi for a given lowering of PTPdi with the PAV was significantly correlated (r = 0.61, P = 0.01). Ventilatory assist during exercise elicits a reduction in the electrical activity of the diaphragm, and there is a proportional lowering of the work of breathing. Our findings have implications for exercise training studies using assisted ventilation to reduce diaphragm work in patients with cardiopulmonary disease.
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Affiliation(s)
- Emily A. M. Gerson
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | | | - Michael G. Leahy
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - Shalaya Kipp
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - Jordan A. Guenette
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Centre for Heart Lung InnovationProvidence ResearchThe University of British Columbia, St. Paul's HospitalVancouverBritish ColumbiaCanada
- Department of Physical TherapyFaculty of MedicineThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - Bruno Archiza
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Department of PhysiotherapyCardiopulmonary Physiotherapy LaboratoryNucleus of Research in Physical Exercise, Federal University of Sao CarlosSao CarlosBrazil
| | - Andrew William Sheel
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
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16
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Mann LM, Chan JS, Angus SA, Doherty CJ, Thompson BP, Foster GE, Hughson RL, Dominelli PB. Peripheral hypercapnic chemosensitivity in trained and untrained females and males during exercise. J Appl Physiol (1985) 2022; 133:1309-1317. [PMID: 36302156 DOI: 10.1152/japplphysiol.00460.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Hypercapnic chemosensitivity is the response to the increased partial pressure of carbon dioxide and results from central and peripheral chemosensor stimulation. The hypercapnic chemosensitivity of the peripheral chemoreceptors is potentially impacted by acute exercise, aerobic fitness, and sex. We sought to determine the peripheral chemoresponse to transient hypercapnia at rest and during exercise in males and females of various fitness. We hypothesized that 1) higher fitness participants would have lower hypercapnic chemosensitivity compared with those with lower fitness and 2) males would have a higher chemoresponse than females. Forty healthy participants (20 females) participated in one test day involving transient hypercapnic chemosensitivity testing and a maximal exercise test. Chemosensitivity testing involved two breaths of 10% CO2 repeated five times (45 s to 1 min between repeats) at rest and the first two stages of a maximal exercise test. There was no significant difference between higher and lower aerobic fitness groups, (mean difference 0.23 ± 0.22 rest; -0.07 ± 0.04 stage 1; 0.11 ± 0.17 stage 2 L/mmHg·min) during each stage (P = 0.472). However, we saw a significant increase in the hypercapnic response during stage 1 (0.98 ± 0.4 L/mmHg·min) compared with rest (0.79 ± 0.5 L/mmHg·min; P = 0.01). Finally, at 80 W, males had a higher chemoresponse compared with females, which persisted following body surface area correction (0.56 ± 0.2 vs. 0.42 ± 0.2 L/mmHg·min·m2, for females and males respectively (P = 0.038). Our findings suggest that sex, unlike aerobic fitness, influences peripheral hypercapnic chemosensitivity and that context (i.e., rest vs. exercise) is an important consideration.NEW & NOTEWORTHY The hypercapnic chemoresponse to transient CO2 showed an increase during acute physical activity; however, this response did not persist with further increases in intensity and was not different between participants of different aerobic fitness. Males and females show a differing response to CO2 during exercise when compared with an iso-V̇co2. Our results suggest that adaptations that lead to increased aerobic fitness do not impact the hypercapnic ventilatory response but there is an effect of sex.
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Affiliation(s)
- Leah M Mann
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Jason S Chan
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Sarah A Angus
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Connor J Doherty
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin P Thompson
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Glen E Foster
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Richard L Hughson
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.,Schlegel-UW Research Institute for Aging, Waterloo, Ontario, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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17
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Jeltema JL, Gorman EK, Ovrom EA, Ripoll JG, Dominelli PB, Joyner MJ, Welch BT, Senefeld JW, Wiggins CC. Greater central airway luminal area in people with COVID-19: a case-control series. Sci Rep 2022; 12:17970. [PMID: 36289306 PMCID: PMC9606286 DOI: 10.1038/s41598-022-22005-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/07/2022] [Indexed: 01/24/2023] Open
Abstract
Respiratory epithelium in the conducting airways of the human body is one of the primary targets of SARS-CoV-2 infection, however, there is a paucity of studies describing the association between COVID-19 and physical characteristics of the conducting airways. To better understand the pathophysiology of COVID-19 on the size of larger conducting airways, we determined the luminal area of the central airways in patients with a history of COVID-19 compared to a height-matched cohort of controls using a case-control study design. Using three-dimensional reconstruction from low-dose high-resolution computed tomography, we retrospectively assessed airway luminal cross-sectional area in 114 patients with COVID-19 (66 females, 48 males) and 114 healthy, sex- and height-matched controls (66 females, 48 males). People with a history of smoking, cardiopulmonary disease, or a body mass index greater than 40 kg·m-2 were excluded. Luminal areas of seven conducting airways were analyzed, including trachea, left and right main bronchus, intermediate bronchus, left and right upper lobe, and left lower lobe. For the central conducting airways, luminal area was ~ 15% greater patients with COVID-19 compared to matched controls (p < 0.05). Among patients with COVID-19, there were generally no differences in the luminal areas of the conducting airways between hospitalized patients compared to patients who did not require COVID-19-related hospitalization. Our findings suggest that males and females with COVID-19 have pathologically larger conducting airway luminal areas than healthy, sex- and height-matched controls.
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Affiliation(s)
- Jeffrey L Jeltema
- Alix School of Medicine, Mayo Clinic, Rochester, MN, USA
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Ellen K Gorman
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Erik A Ovrom
- Alix School of Medicine, Mayo Clinic, Rochester, MN, USA
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Juan G Ripoll
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Brian T Welch
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - Jonathon W Senefeld
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
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18
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Dominelli PB. Respiratory muscle metaboreflex: Connecting the 'dots'. Exp Physiol 2022; 107:1013-1014. [PMID: 35866454 DOI: 10.1113/ep090659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 07/11/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Paolo B Dominelli
- Department of Kinesiology and Health Science, Faculty of Health, University of Waterloo
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19
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Webb KL, Elshaer AN, Dominelli PB, Senefeld JW, Hammer SM, Baker SE, Shepherd JRA, Roy TK, Joyner MJ, Wiggins CC. Muscle oxygenation during normoxic and hypoxic cycling exercise in humans with high affinity haemoglobin. Exp Physiol 2022; 107:854-863. [PMID: 35603981 PMCID: PMC9357130 DOI: 10.1113/ep090308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 05/17/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do humans with high affinity haemoglobin (HAH) demonstrate attenuated skeletal muscle deoxygenation during normoxic and hypoxic exercise? What is the main finding and its importance? Examination of NIRS-derived muscle oxygenation profiles suggests that fractional oxygen extraction is blunted during hypoxic exercise in humans with HAH compared to controls. However, muscle tissue oxygen saturation levels were higher in humans with HAH during exercise in normoxia compared to controls. These alterations in fractional oxygen extraction in humans with HAH may influence blood flow regulation and exercise capacity during hypoxia. ABSTRACT Recently, our lab has shown that humans with genetic mutations resulting in high affinity haemoglobin (HAH) demonstrate better maintained aerobic capacity and peak power output during hypoxic exercise versus normoxic exercise compared to humans with normal affinity haemoglobin. However, the influence of HAH on tissue oxygenation within exercising muscle during normoxia and hypoxia is unknown. Therefore, we examined near-infrared spectroscopy (NIRS)-derived oxygenation profiles of the vastus lateralis during graded cycling exercise in normoxia and hypoxia among humans with HAH (n = 5) and controls with normal affinity haemoglobin (n = 12). The HAH group elicited a blunted increase of deoxygenated haemoglobin+myoglobin during hypoxic exercise compared to the control group (P = 0.03), suggesting reduced fractional oxygen extraction in the HAH group. In addition, the HAH group maintained a higher level of muscle tissue oxygen saturation during normoxic exercise (HAH, 75 ± 4% vs. controls, 65 ± 3%, P = 0.049) and there were no differences between groups in muscle tissue oxygen saturation during hypoxic exercise (HAH, 68 ± 3% vs. controls, 68 ± 2%, P = 0.943). Overall, our results suggest that humans with HAH may demonstrate divergent patterns of fractional oxygen extraction during hypoxic exercise and elevated muscle tissue oxygenation during normoxic exercise compared to controls. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kevin L Webb
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Ahmed N Elshaer
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States.,College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Paolo B Dominelli
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States.,Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Jonathon W Senefeld
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Shane M Hammer
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - John R A Shepherd
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Tuhin K Roy
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, United States
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20
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Pruter WW, Klassen SA, Dominelli PB, Wiggins CC, Senefeld JW, Roy TK, Joyner MJ, Baker SE. Cardiac baroreflex sensitivity and heart rate variability are lower in humans with high affinity hemoglobin compared to typical affinity hemoglobin. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.0r874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Angus SA, Henderson WR, Banoei MM, Molgat‐Seon Y, Peters CM, Parmar HR, Griesdale DEG, Sekhon M, Sheel AW, Winston BW, Dominelli PB. Therapeutic hypothermia attenuates physiologic, histologic, and metabolomic markers of injury in a porcine model of acute respiratory distress syndrome. Physiol Rep 2022; 10:e15286. [PMID: 35510328 PMCID: PMC9069168 DOI: 10.14814/phy2.15286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 03/29/2022] [Accepted: 04/02/2022] [Indexed: 06/14/2023] Open
Abstract
Acute respiratory distress syndrome (ARDS) is a lung injury characterized by noncardiogenic pulmonary edema and hypoxic respiratory failure. The purpose of this study was to investigate the effects of therapeutic hypothermia on short-term experimental ARDS. Twenty adult female Yorkshire pigs were divided into four groups (n = 5 each): normothermic control (C), normothermic injured (I), hypothermic control (HC), and hypothermic injured (HI). Acute respiratory distress syndrome was induced experimentally via intrapulmonary injection of oleic acid. Target core temperature was achieved in the HI group within 1 h of injury induction. Cardiorespiratory, histologic, cytokine, and metabolomic data were collected on all animals prior to and following injury/sham. All data were collected for approximately 12 h from the beginning of the study until euthanasia. Therapeutic hypothermia reduced injury in the HI compared to the I group (histological injury score = 0.51 ± 0.18 vs. 0.76 ± 0.06; p = 0.02) with no change in gas exchange. All groups expressed distinct phenotypes, with a reduction in pro-inflammatory metabolites, an increase in anti-inflammatory metabolites, and a reduction in inflammatory cytokines observed in the HI group compared to the I group. Changes to respiratory system mechanics in the injured groups were due to increases in lung elastance (E) and resistance (R) (ΔE from pre-injury = 46 ± 14 cmH2 O L-1 , p < 0.0001; ΔR from pre-injury: 3 ± 2 cmH2 O L-1 s- , p = 0.30) rather than changes to the chest wall (ΔE from pre-injury: 0.7 ± 1.6 cmH2 O L-1 , p = 0.99; ΔR from pre-injury: 0.6 ± 0.1 cmH2 O L-1 s- , p = 0.01). Both control groups had no change in respiratory mechanics. In conclusion, therapeutic hypothermia can reduce markers of injury and inflammation associated with experimentally induced short-term ARDS.
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Affiliation(s)
- Sarah A. Angus
- Department of KinesiologyUniversity of WaterlooWaterlooOntarioCanada
| | - William R. Henderson
- Division of Critical Care MedicineDepartment of MedicineFaculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Mohammad M. Banoei
- Department of Critical Care MedicineUniversity of CalgaryCalgaryAlbertaCanada
| | - Yannick Molgat‐Seon
- Department Kinesiology and Applied HealthUniversity of WinnipegWinnipegManitobaCanada
| | - Carli M. Peters
- School of KinesiologyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Hanna R. Parmar
- School of KinesiologyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Donald E. G. Griesdale
- Division of Critical Care MedicineDepartment of MedicineFaculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
- Department of AnesthesiologyPharmacology & TherapeuticsUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Mypinder Sekhon
- Division of Critical Care MedicineDepartment of MedicineFaculty of MedicineUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Andrew William Sheel
- School of KinesiologyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Brent W. Winston
- Department of Critical Care MedicineUniversity of CalgaryCalgaryAlbertaCanada
- Departments of Medicine and Biochemistry & Molecular BiologyUniversity of CalgaryCalgaryAlbertaCanada
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22
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Abstract
In this review, we detail how the pulmonary system's response to exercise is impacted by both sex and gender in healthy humans across the lifespan. First, the rationale for why sex and gender differences should be considered is explored, and then anatomical differences are highlighted, namely that females typically have smaller lungs and airways than males. Thereafter, we describe how these anatomical differences can impact functional aspects such as respiratory muscle energetics and activation, mechanical ventilatory constraints, diaphragm fatigue, and pulmonary gas exchange in healthy adults and children. Finally, we detail how gender can impact the pulmonary response to exercise. Biological sex can influence the pulmonary response to exercise in healthy individuals across the lifespanhttps://bit.ly/3ejMDrv
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Affiliation(s)
| | - Yannick Molgat-Seon
- Dept of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, MB, Canada.,Centre for Heart and Lung Innovation, Providence Health Care Research Institute, St Paul's Hospital, Vancouver, BC, Canada
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23
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Hedge ET, Hughson RL, Dominelli PB. Repeatability and reproducibility of changes in thoracoabdominal compartmental volumes and breathing pattern during low-, moderate- and heavy-intensity exercise. Eur J Appl Physiol 2022; 122:1217-1229. [DOI: 10.1007/s00421-022-04917-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 02/15/2022] [Indexed: 11/03/2022]
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24
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Webb KL, Dominelli PB, Baker SE, Klassen SA, Joyner MJ, Senefeld JW, Wiggins CC. Influence of High Hemoglobin-Oxygen Affinity on Humans During Hypoxia. Front Physiol 2022; 12:763933. [PMID: 35095551 PMCID: PMC8795792 DOI: 10.3389/fphys.2021.763933] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/22/2021] [Indexed: 01/11/2023] Open
Abstract
Humans elicit a robust series of physiological responses to maintain adequate oxygen delivery during hypoxia, including a transient reduction in hemoglobin-oxygen (Hb-O2) affinity. However, high Hb-O2 affinity has been identified as a beneficial adaptation in several species that have been exposed to high altitude for generations. The observed differences in Hb-O2 affinity between humans and species adapted to high altitude pose a central question: is higher or lower Hb-O2 affinity in humans more advantageous when O2 availability is limited? Humans with genetic mutations in hemoglobin structure resulting in high Hb-O2 affinity have shown attenuated cardiorespiratory adjustments during hypoxia both at rest and during exercise, providing unique insight into this central question. Therefore, the purpose of this review is to examine the influence of high Hb-O2 affinity during hypoxia through comparison of cardiovascular and respiratory adjustments elicited by humans with high Hb-O2 affinity compared to those with normal Hb-O2 affinity.
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Affiliation(s)
- Kevin L. Webb
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
| | | | - Sarah E. Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
| | - Stephen A. Klassen
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Michael J. Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
| | - Jonathon W. Senefeld
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
| | - Chad C. Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
- *Correspondence: Chad C. Wiggins,
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25
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Doherty CJ, Mann LM, Angus SA, Chan JS, Molgat-Seon Y, Dominelli PB. Impact Of Wearing A Mask During Cycling Exercise. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760244.94590.ef] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Katayama K, Dominelli PB, Foster GE, Kipp S, Leahy MG, Ishida K, Sheel AW. Respiratory modulation of sympathetic vasomotor outflow during graded leg cycling. J Appl Physiol (1985) 2021; 131:858-867. [PMID: 34197231 DOI: 10.1152/japplphysiol.00118.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Respiratory modulation of sympathetic vasomotor outflow to skeletal muscles (muscle sympathetic nerve activity; MSNA) occurs in resting humans. Specifically, MSNA is highest at end-expiration and lowest at end-inspiration during quiet, resting breathing. We tested the hypothesis that within-breath modulation of MSNA would be amplified during graded leg cycling. Thirteen (n = 3 females) healthy young (age: 25.2 ± 4.7 yr) individuals completed all testing. MSNA (right median nerve) was measured at rest (baseline) and during semirecumbent cycle exercise at 40%, 60%, and 80% of maximal workload (Wmax). MSNA burst frequency (BF) was 20.0 ± 4.0 bursts/min at baseline and was not different during exercise at 40%Wmax (21.3 ± 3.7 bursts/min; P = 0.292). Thereafter, MSNA BF increased significantly compared with baseline (60%Wmax: 31.6 ± 5.8 bursts/min; P < 0.001, 80%Wmax: 44.7 ± 5.3 bursts/min; P < 0.001). At baseline and all exercise intensities, MSNA BF was lowest at end-inspiration and greatest at mid-to-end expiration. The within-breath change in MSNA BF (ΔMSNA BF; end-expiration minus end-inspiration) gradually increased from baseline to 60%Wmax leg cycling, but no further increase appeared at 80%Wmax exercise. Our results indicate that within-breath modulation of MSNA is amplified from baseline to moderate intensity during dynamic exercise in young healthy individuals, and that no further potentiation occurs at higher exercise intensities. Our findings provide an important extension of our understanding of respiratory influences on sympathetic vasomotor control.NEW & NOTEWORTHY Within-breath modulation of sympathetic vasomotor outflow to skeletal muscle (muscle sympathetic nerve activity; MSNA) occurs in spontaneously breathing humans at rest. It is unknown if respiratory modulation persists during dynamic whole body exercise. We found that MSNA burst frequency was lowest at end-inspiration and highest at mid-to-end expiration during rest and graded leg cycling. Respiratory modulation of sympathetic vasomotor outflow remains intact and is amplified during dynamic whole body exercise.
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Affiliation(s)
- Keisho Katayama
- Research Center of Health, Physical Fitness and Sports, Graduate School of Medicine, Nagoya University, Nagoya, Japan
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Shalaya Kipp
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael G Leahy
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Koji Ishida
- Research Center of Health, Physical Fitness and Sports, Graduate School of Medicine, Nagoya University, Nagoya, Japan
| | - Andrew William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
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27
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Doherty CJ, Mann LM, Angus SA, Chan JS, Molgat-Seon Y, Dominelli PB. Impact of wearing a surgical and cloth mask during cycle exercise. Appl Physiol Nutr Metab 2021; 46:753-762. [PMID: 33960846 DOI: 10.1139/apnm-2021-0190] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We sought to determine the impact of wearing cloth or surgical masks on the cardiopulmonary responses to moderate-intensity exercise. Twelve subjects (n = 5 females) completed three, 8-min cycling trials while breathing through a non-rebreathing valve (laboratory control), cloth, or surgical mask. Heart rate (HR), oxyhemoglobin saturation (SpO2), breathing frequency, mouth pressure, partial pressure of end-tidal carbon dioxide (PetCO2) and oxygen (PetO2), dyspnea were measured throughout exercise. A subset of n = 6 subjects completed an additional exercise bout without a mask (ecological control). There were no differences in breathing frequency, HR or SpO2 across conditions (all p > 0.05). Compared with the laboratory control (4.7 ± 0.9 cmH2O [mean ± SD]), mouth pressure swings were smaller with the surgical mask (0.9 ± 0.7; p < 0.0001), but similar with the cloth mask (3.6 ± 4.8 cmH2O; p = 0.66). Wearing a cloth mask decreased PetO2 (-3.5 ± 3.7 mm Hg) and increased PetCO2 (+2.0 ± 1.3 mm Hg) relative to the ecological control (both p < 0.05). There were no differences in end-tidal gases between mask conditions and laboratory control (both p > 0.05). Dyspnea was similar between the control conditions and the surgical mask (p > 0.05) but was greater with the cloth mask compared with laboratory (+0.9 ± 1.2) and ecological (+1.5 ± 1.3) control conditions (both p < 0.05). Wearing a mask during short-term moderate-intensity exercise may increase dyspnea but has minimal impact on the cardiopulmonary response. Novelty: Wearing surgical or cloth masks during exercise has no impact on breathing frequency, tidal volume, oxygenation, and heart rate However, there are some changes in inspired and expired gas fractions that are physiologically irrelevant. In young healthy individuals, wearing surgical or cloth masks during submaximal exercise has few physiological consequences.
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Affiliation(s)
- Connor J Doherty
- Department of Kinesiology, Faculty of Health, University of Waterloo, Waterloo, Ontario, Canada
| | - Leah M Mann
- Department of Kinesiology, Faculty of Health, University of Waterloo, Waterloo, Ontario, Canada
| | - Sarah A Angus
- Department of Kinesiology, Faculty of Health, University of Waterloo, Waterloo, Ontario, Canada
| | - Jason S Chan
- Department of Kinesiology, Faculty of Health, University of Waterloo, Waterloo, Ontario, Canada
| | - Yannick Molgat-Seon
- Centre for Heart Lung Innovation, St. Paul's Hospital, The University of British Columbia, Vancouver, British Columbia, Canada.,The Gupta Faculty of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, Faculty of Health, University of Waterloo, Waterloo, Ontario, Canada
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28
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Dominelli PB, Wiggins CC, Roy TK, Secomb TW, Curry TB, Joyner MJ. The Oxygen Cascade During Exercise in Health and Disease. Mayo Clin Proc 2021; 96:1017-1032. [PMID: 33714599 PMCID: PMC8026750 DOI: 10.1016/j.mayocp.2020.06.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/08/2020] [Accepted: 06/29/2020] [Indexed: 12/28/2022]
Abstract
The oxygen transport cascade describes the physiological steps that bring atmospheric oxygen into the body where it is delivered and consumed by metabolically active tissue. As such, the oxygen cascade is fundamental to our understanding of exercise in health and disease. Our narrative review will highlight each step of the oxygen transport cascade from inspiration of atmospheric oxygen down to mitochondrial consumption in both healthy active males and females along with clinical conditions. We will focus on how different steps interact along with principles of homeostasis, physiological redundancies, and adaptation. In particular, we highlight some of the parallels between elite athletes and clinical conditions in terms of the oxygen cascade.
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Affiliation(s)
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Tuhin K Roy
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Timothy W Secomb
- Departments of Physiology and Mathematics, University of Arizona, Tucson
| | - Timothy B Curry
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN.
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29
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Senefeld JW, Wiggins CC, Regimbal RJ, Dominelli PB, Baker SE, Joyner MJ. Ergogenic Effect of Nitrate Supplementation: A Systematic Review and Meta-analysis. Med Sci Sports Exerc 2021; 52:2250-2261. [PMID: 32936597 PMCID: PMC7494956 DOI: 10.1249/mss.0000000000002363] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Supplemental digital content is available in the text. Although over 100 studies and reviews have examined the ergogenic effects of dietary nitrate (NO3−) supplementation in young, healthy men and women, it is unclear if participant and environmental factors modulate the well-described ergogenic effects—particularly relevant factors include biological sex, aerobic fitness, and fraction of inspired oxygen (FiO2) during exercise. To address this limitation, the literature was systematically reviewed for randomized, crossover, placebo-controlled studies reporting exercise performance outcome metrics with NO3− supplementation in young, healthy adults. Of the 2033 articles identified, 80 were eligible for inclusion in the meta-analysis. Random-effects meta-analysis demonstrated that exercise performance improved with NO3− supplementation compared with placebo (d = 0.174; 95% confidence interval (CI), 0.120–0.229; P < 0.001). Subgroup analyses conducted on biological sex, aerobic fitness, and FiO2 demonstrated that the ergogenic effect of NO3− supplementation was as follows: 1) not observed in studies with only women (n = 6; d = 0.116; 95% CI, −0.126 to 0.358; P = 0.347), 2) not observed in well-trained endurance athletes (≥65 mL·kg−1·min−1; n = 26; d = 0.021; 95% CI, −0.103 to 0.144; P = 0.745), and 3) not modulated by FiO2 (hypoxia vs normoxia). Together, the meta-analyses demonstrated a clear ergogenic effect of NO3− supplementation in recreationally active, young, healthy men across different exercise paradigms and NO3− supplementation parameters; however, the effect size of NO3− supplementation was objectively small (d = 0.174). NO3− supplementation has more limited utility as an ergogenic aid in participants with excellent aerobic fitness that have optimized other training parameters. Mechanistic research and studies incorporating a wide variety of subjects (e.g., women) are needed to advance the study of NO3− supplementation; however, additional descriptive studies of young, healthy men may have limited utility.
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Affiliation(s)
- Jonathon W Senefeld
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Riley J Regimbal
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | | | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN
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30
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Hopkins SR, Dominelli PB, Davis CK, Guenette JA, Luks AM, Molgat-Seon Y, Sá RC, Sheel AW, Swenson ER, Stickland MK. Face Masks and the Cardiorespiratory Response to Physical Activity in Health and Disease. Ann Am Thorac Soc 2021; 18:399-407. [PMID: 33196294 PMCID: PMC7919154 DOI: 10.1513/annalsats.202008-990cme] [Citation(s) in RCA: 93] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 11/16/2020] [Indexed: 11/21/2022] Open
Abstract
To minimize transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the novel coronavirus responsible for coronavirus disease (COVID-19), the U.S. Centers for Disease Control and Prevention and the World Health Organization recommend wearing face masks in public. Some have expressed concern that these may affect the cardiopulmonary system by increasing the work of breathing, altering pulmonary gas exchange and increasing dyspnea, especially during physical activity. These concerns have been derived largely from studies evaluating devices intentionally designed to severely affect respiratory mechanics and gas exchange. We review the literature on the effects of various face masks and respirators on the respiratory system during physical activity using data from several models: cloth face coverings and surgical masks, N95 respirators, industrial respirators, and applied highly resistive or high-dead space respiratory loads. Overall, the available data suggest that although dyspnea may be increased and alter perceived effort with activity, the effects on work of breathing, blood gases, and other physiological parameters imposed by face masks during physical activity are small, often too small to be detected, even during very heavy exercise. There is no current evidence to support sex-based or age-based differences in the physiological responses to exercise while wearing a face mask. Although the available data suggest that negative effects of using cloth or surgical face masks during physical activity in healthy individuals are negligible and unlikely to impact exercise tolerance significantly, for some individuals with severe cardiopulmonary disease, any added resistance and/or minor changes in blood gases may evoke considerably more dyspnea and, thus, affect exercise capacity.
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Affiliation(s)
| | - Paolo B. Dominelli
- Department of Pediatrics, University of California, San Diego, California
| | | | - Jordan A. Guenette
- Centre for Heart Lung Innovation
- Department of Physical Therapy, Faculty of Medicine, and
- School of Kinesiology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrew M. Luks
- St. Paul’s Hospital, Vancouver, British Columbia, Canada
| | - Yannick Molgat-Seon
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Seattle, Washington
| | | | - A. William Sheel
- Department of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Erik R. Swenson
- St. Paul’s Hospital, Vancouver, British Columbia, Canada
- Medical Service, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
| | - Michael K. Stickland
- Division of Pulmonary Medicine, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada; and
- G. F. MacDonald Centre for Lung Health (Covenant Health) and
- Medicine Strategic Clinical Network, Alberta Health Services, Edmonton, Alberta, Canada
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31
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Peters CM, Molgat‐Seon Y, Dominelli PB, Lee AMD, Lane P, Lam S, Sheel AW. Fiber optic endoscopic optical coherence tomography (OCT) to assess human airways: The relationship between anatomy and physiological function during dynamic exercise. Physiol Rep 2021; 9:e14657. [PMID: 33369886 PMCID: PMC7769176 DOI: 10.14814/phy2.14657] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 10/27/2020] [Indexed: 11/24/2022] Open
Abstract
Airway luminal area (Ai ) influences respiratory mechanics during dynamic exercise; however, previous studies have investigated the relationship between airway anatomy and physiological function in different groups of individuals. The purpose of this study was to determine the effect of Ai on respiratory mechanics by making in vivo measures of airway dimensions and work of breathing (Wb) in the same individuals. Healthy participants (3F/2M; 23-45 years) completed a cycle exercise test to exhaustion. During exercise, Wb was assessed using an esophageal balloon catheter, while simultaneously assessing minute ventilation ( V ˙ E ). On a separate day, subjects underwent a bronchoscopy procedure to capture optical coherence tomography (OCT) measures of three airways in the right lung. Each participant's Wb- V ˙ E data were fit to a non-linear regression equation (Wb = a V ˙ E3 + b V ˙ E2 ) that partitions Wb into its turbulent resistive (a) and viscoelastic (b) components. Measures of Ai and luminal diameter were made for the 4th-6th airway generations. A composite index of airway size was calculated as the sum of the Ai for each generation and the total area of the 4th-6th generation was calculated based on Weibel's model. Constant a was significantly correlated to the Weibel model total airway area (r = -0.94, p = 0.017) and index of airway size (r = -0.929, p = 0.023), whereas constant b was not associated with either measure (both p > 0.05). We found that individuals who had the smallest Ai had the highest resistive Wb and our findings provide the basis for further study of the relationship between airway size and respiratory mechanics during exercise.
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Affiliation(s)
- Carli M. Peters
- School of KinesiologyUniversity of British ColumbiaVancouverBCCanada
| | - Yannick Molgat‐Seon
- School of KinesiologyUniversity of British ColumbiaVancouverBCCanada
- Department of Kinesiology and Applied HealthUniversity of WinnipegWinnipegMBCanada
| | - Paolo B. Dominelli
- School of KinesiologyUniversity of British ColumbiaVancouverBCCanada
- Department of KinesiologyUniversity of WaterlooWaterlooONCanada
| | - Anthony M. D. Lee
- Integrative Oncology Department Imaging UnitBC Cancer Research CenterVancouverBCCanada
| | - Pierre Lane
- Integrative Oncology Department Imaging UnitBC Cancer Research CenterVancouverBCCanada
- School of Engineering ScienceSimon Fraser UniversityBurnabyBCCanada
| | - Stephen Lam
- Integrative Oncology Department Imaging UnitBC Cancer Research CenterVancouverBCCanada
| | - Andrew W. Sheel
- School of KinesiologyUniversity of British ColumbiaVancouverBCCanada
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32
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Wiggins CC, Baker SE, Shepherd JRA, Uchida K, Joyner MJ, Dominelli PB. Body position does not influence muscle oxygenation during submaximal cycling. Transl Sports Med 2020. [DOI: 10.1002/tsm2.202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Chad C. Wiggins
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic Rochester MN USA
| | - Sarah E. Baker
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic Rochester MN USA
| | - John R. A. Shepherd
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic Rochester MN USA
| | - Koji Uchida
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic Rochester MN USA
| | - Michael J. Joyner
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic Rochester MN USA
| | - Paolo B. Dominelli
- Department of Anesthesiology and Perioperative Medicine Mayo Clinic Rochester MN USA
- Department of Kinesiology University of Waterloo Waterloo ON Canada
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33
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Mann LM, Granger EA, Chan JS, Yu A, Molgat-Seon Y, Dominelli PB. Minimizing airflow turbulence in women lowers the work of breathing to levels similar to men. J Appl Physiol (1985) 2020; 129:410-418. [PMID: 32702273 DOI: 10.1152/japplphysiol.00347.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Smaller airways increase resistance and the propensity toward turbulent airflow, both of which are thought to be mechanisms behind greater resistive and total work of breathing (Wb) in females. Previous research examining the effect of airway size on the Wb between the sexes is limited by the inability to experimentally manipulate airway size. Heliox (21% oxygen, balance helium) is less dense than room air, which reduces turbulent airflow and airway resistance. The purpose of our study was to utilize heliox inspiration in women to provide a stimulus physiologically similar to increasing airway size. We hypothesized that when breathing heliox women would have a Wb similar to men breathing room air. Eighteen healthy young subjects (n = 9 women, 9 men) completed two maximal exercise tests on a cycle ergometer over 2 days. Subjects breathed room air for one test and heliox for the other. Wb was assessed with an esophageal balloon catheter. During the room air trial, when ventilations were >65 L/min, women had a significantly greater Wb compared with men (P < 0.05). The greater Wb in women was due to greater resistance to turbulent flow. For both sexes, breathing heliox resulted in increased expiratory flow (+132 ± 18% of room air), an elimination of expiratory flow limitation, and a reduction in Wb (69 ± 12% of room air) (all P < 0.05). When the women were breathing heliox, Wb was not different from that in the men breathing room air. Our findings support the idea that the smaller conducting airways in females are responsible for a greater total and resistive Wb.NEW & NOTEWORTHY When healthy young women breathe heliox gas during exercise, their work of breathing is not different from men breathing room air. Heliox inspiration reduces airway resistance and promotes laminar flow, which is a physiologically similar effect of increasing airway size. Our findings provide experimental evidence that smaller airways in women are responsible for the greater work of breathing during exercise.
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Affiliation(s)
- Leah M Mann
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Emily A Granger
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Jason S Chan
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Annie Yu
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
| | - Yannick Molgat-Seon
- Department of Kinesiology and Applied Health, Gupta Faculty of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, Manitoba, Canada.,Centre for Heart and Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada
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Wiggins CC, Dominelli PB, Senefeld JW, Shepherd JR, Baker SE, Uchida K, Joyner MJ. Skeletal Muscle Endurance And Oxygen Uptake Kinetics During Cycling In Patients With High Affinity Hemoglobin. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000675800.49464.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Guo WL, Eli IM, Ripoll JG, Baker SE, Shepherd JRA, Wiggins CC, Welch BT, Joyner MJ, Dominelli PB. Bronchopulmonary dysplasia patients have preserved CT-measured central airway luminal area. Respir Med 2020; 170:106071. [PMID: 32843156 DOI: 10.1016/j.rmed.2020.106071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/16/2020] [Accepted: 06/22/2020] [Indexed: 10/24/2022]
Abstract
Bronchopulmonary dysplasia (BPD) is a condition of neonatal chronic lung disease due to disruption or dysregulation of pulmonary development. However, the pathophysiology of BPD in the larger conducting airways is not yet fully understood. The objective of our study was to determine if the area of the central airways are altered in patients with a history of BPD. We hypothesized that compared to age- and sex-matched controls, BPD patients would have decreased area of the central conducting airways. Twenty-two BPD patients (n = 10 male, n = 12 female; median age = 10 [range:1-49] yrs) and n = 22 matched controls (n = 10 male, n = 12 female; median age = 10 [range:1-48] yrs) who had undergone a chest computed tomography (CT) scan were retrospectively identified. Measurement and analysis was performed using software that reconstructs the airways into 3D. Measurements of airway area were conducted at three points based on anatomic bifurcations for each of the following structures: trachea, left main bronchus, left upper lobe, left lower lobe, right main bronchus, intermediate bronchus, and right upper lobe. The luminal area for each airway was calculated based on the averages of the three measures. Airway luminal area was not different between BPD patients and matched controls for any of the measured airways (p > 0.05). Total lung volume detected in the CT scans was not different between BPD patients and matched controls (median [range]; 2775 [522-6215] vs 2969 [851-5612] cm3, p > 0.05). Our results suggest the luminal areas of the large conducting airways in patients with BPD are not different from matched controls.
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Affiliation(s)
- Winston L Guo
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Ilhan M Eli
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Juan G Ripoll
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - John R A Shepherd
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Brian T Welch
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.
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Abstract
Healthy women have proportionally smaller lungs and airways compared with height-matched men. These anatomical sex-based differences result in greater mechanical ventilatory constraints and may influence the integrative response to exercise. Our review will examine this hypothesis in healthy humans in the context of dynamic whole-body exercise.
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Affiliation(s)
- Paolo B Dominelli
- Department of Anesthesia, Mayo Clinic, Rochester, MN.,Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada
| | - Yannick Molgat-Seon
- Centre for Heart and Lung Innovation, St. Paul's Hospital.,Department of Physical Therapy, Faculty of Medicine, and
| | - A William Sheel
- School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC, Canada
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Guo WL, Eli IM, Ripoll JG, Baker SE, Shepherd JR, Wiggins CC, Joyner MJ, Dominelli PB. Bronchopulmonary Dysplasia Patients Have Preserved CT‐Measured Central Airway Luminal Area. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.03321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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38
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Wiggins CC, Dominelli PB, Senefeld JW, Shepherd JR, Baker SE, Uchida K, Joyner MJ. Skeletal muscle blood flow and vascular conductance are enhanced in humans with high‐affinity hemoglobin during handgrip exercise in severe hypoxia. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.00495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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39
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Ahmed EN, Dominelli PB, Baker SE, Shepherd JR, Hoyer JD, Oliveira JL, Joyner MJ, Wiggins CC. Muscle oxygenation during hypoxic exercise in humans: Effect of high‐affinity hemoglobin. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.00275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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Ripoll JG, Guo W, Andersen KJ, Baker SE, Wiggins CC, Shepherd JRA, Carter RE, Welch BT, Joyner MJ, Dominelli PB. Sex differences in paediatric airway anatomy. Exp Physiol 2020; 105:721-731. [PMID: 32003484 DOI: 10.1113/ep088370] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 01/24/2020] [Indexed: 12/15/2022]
Abstract
NEW FINDINGS What is the central question of this study? Are sex difference in the central airways present in healthy paediatric patients? What is the main finding and its importance? In patients ≤12 years we found no sex differences in central airway luminal area. After 14 years, the males had significantly larger central airway luminal areas than the females. The sex differences were minimized, but preserved when correcting for height. Luminal area is the main determinant of airway resistance and our finding could help explain sex differences in pulmonary system limitations to exercise in paediatric patients. ABSTRACT Cross-sectional airway area is the main determinant of resistance to airflow in the respiratory system. In paediatric patients (<18 years), previous evidence for sex differences in cross-sectional airway area was limited to patients with history of pulmonary disease or cadaveric studies with small numbers of subjects. These studies either only report tracheal data and do not include a range of ages or correct for height. Therefore, we sought to assess sex differences in airway luminal area utilizing paediatric patients of varying ages and no history of respiratory disease. Using three-dimensional reconstructions from high-resolution computed tomography scans, we retrospectively assessed the cross-sectional airway area in healthy paediatric females (n = 97) and males (n = 128) over a range of ages (1-17 years). The areas of the trachea, left main bronchus, left upper lobe, left lower lobe, right main bronchus, intermediate bronchus and right upper lobe were measured at three discrete points by a blinded investigator. No differences between the sexes were noted in the cross-sectional areas of the youngest (ages 1-12 years) patients (P > 0.05). However, in patients ≥14 years the cross-sectional areas were larger in the males compared to females in most airway sites. For instance, the cross-sectional size of the trachea was 25% (218 ± 44 vs. 163 ± 24 mm2 , P < 0.01) larger in males vs. females among ages 13-17 years. When accounting for height, these sex differences in airway areas were attenuated, but persisted. Our results indicate that sex differences in paediatric airway cross-sectional area manifest after age ≥14 years and are independent of height.
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Affiliation(s)
- Juan G Ripoll
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Winston Guo
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Kylie J Andersen
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - John R A Shepherd
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Rickey E Carter
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | - Brian T Welch
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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Abstract
NEW FINDINGS What is the topic of this review? The limits to maximal aerobic capacity. What advances does it highlight? A synthesis of data and ideas about what limits maximal aerobic capacity demonstrates the central roles of cardiac output, stroke volume and red blood cell mass in the complex physiological responses to maximal exercise. In healthy humans these factors, along with skeletal muscle blood flow, dominate systemic delivery of oxygen to the contracting muscles and set the upper limit of aerobic energy production by skeletal muscles. In elite athletes and patients with pulmonary disease the lungs can also limit oxygen uptake and delivery. ABSTRACT In this paper we review the physiological determinants of V ̇ O 2 max and discuss the role this variable plays as a determinant of endurance exercise performance. Because the ability to sustain a given pace during a competitive athletic event requires competitors to 'manage' fatigue and go as fast as possible without fatiguing prematurely, V ̇ O 2 max is one of the variables that sets the physiological upper limit for sustained energy production by the contracting skeletal muscles.
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Affiliation(s)
- Michael J Joyner
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Rochester, MN, 55905, USA
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada, N2L 3G1
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42
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Dominelli PB, Wiggins CC, Baker SE, Shepherd JRA, Roberts SK, Roy TK, Curry TB, Hoyer JD, Oliveira JL, Joyner MJ. Influence of high affinity haemoglobin on the response to normoxic and hypoxic exercise. J Physiol 2020; 598:1475-1490. [PMID: 31923331 DOI: 10.1113/jp279161] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/20/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Theoretical models suggest there is no benefit of high affinity haemoglobin to preserve maximal oxygen uptake in acute hypoxia but the comparative biology literature has many examples of species that are evolutionarily adapted to hypoxia and have high affinity haemoglobin. We studied humans with high affinity haemoglobin and compensatory polycythaemia. These subjects performed maximal exercise tests in normoxia and hypoxia to determine how their altered haemoglobin affinity impacts hypoxic exercise tolerance. The high affinity haemoglobin participants demonstrated an attenuated decline in maximal aerobic capacity in acute hypoxia. Those with high affinity haemoglobin had no worsening of pulmonary gas exchange during hypoxic exercise but had greater lactate and lower pH than controls for all exercise bouts. High affinity haemoglobin and compensatory polycythaemia mitigated the decline in exercise performance in acute hypoxia through a higher arterial oxygen content and an unchanged pulmonary gas exchange. ABSTRACT The longstanding dogma is that humans exhibit an acute reduction in haemoglobin (Hb) binding affinity for oxygen that facilitates adaptation to moderate hypoxia. However, many animals have adapted to high altitude through enhanced Hb binding affinity for oxygen. The objective of the study was to determine whether high affinity haemoglobin (HAH) affects maximal and submaximal exercise capacity. To accomplish this, we recruited individuals (n = 11, n = 8 females) with HAH (P50 = 16 ± 1 mmHg), had them perform normoxic and acute hypoxic (15% inspired oxygen) maximal exercise tests, and then compared their results to matched controls (P50 = 26 ± 1, n = 14, n = 8 females). Cardiorespiratory and arterial blood gases were collected throughout both exercise tests. Despite no difference in end-exercise arterial oxygen tension in hypoxia (59 ± 6 vs. 59 ± 9 mmHg for controls and HAH, respectively), the HAH subjects' oxyhaemoglobin saturation ( S a , O 2 ) was ∼7% higher. Those with HAH had an attenuated decline in maximal oxygen uptake ( V ̇ O 2 max ) (4 ± 5% vs. 12 ± %, p < 0.001) in hypoxia and the change in V ̇ O 2 max between trials was related to the change in S a O 2 (r = -0.75, p < 0.0001). Compared to normoxia, the controls' alveolar-to-arterial oxygen gradient significantly increased during hypoxic exercise, whereas pulmonary gas exchange in HAH subjects was unchanged between the two exercise trials. However, arterial lactate was significantly higher and arterial pH significantly lower in the HAH subjects for both exercise trials. We conclude that HAH attenuates the decline in maximal aerobic capacity and preserves pulmonary gas exchange during acute hypoxic exercise. Our data support the comparative biology literature indicating that HAH is a positive adaptation to acute hypoxia.
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Affiliation(s)
- Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.,Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - John R A Shepherd
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Shelly K Roberts
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Tuhin K Roy
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Timothy B Curry
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - James D Hoyer
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Jennifer L Oliveira
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
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43
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Dominelli PB, Baker SE, Wiggins CC, Stewart GM, Sajgalik P, Shepherd JRA, Roberts SK, Roy TK, Curry TB, Hoyer JD, Oliveira JL, Foster GE, Joyner MJ. Dissociating the effects of oxygen pressure and content on the control of breathing and acute hypoxic response. J Appl Physiol (1985) 2019; 127:1622-1631. [PMID: 31647724 PMCID: PMC6962610 DOI: 10.1152/japplphysiol.00569.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/18/2019] [Accepted: 10/20/2019] [Indexed: 11/22/2022] Open
Abstract
Arterial oxygen tension and oxyhemoglobin saturation (S a O 2 ) decrease in parallel during hypoxia. Distinguishing between changes in oxygen tension and oxygen content as the relevant physiological stimulus for cardiorespiratory alterations remains challenging. To overcome this, we recruited nine individuals with hemoglobinopathy manifesting as high-affinity hemoglobin [HAH; partial pressure at 50% S a O 2 (P50) = 16 ± 0.4 mmHg] causing greater S a O 2 at a given oxygen partial pressure compared with control subjects (n = 12, P50 = 26 ± 0.4 mmHg). We assessed ventilatory and cardiovascular responses to acute isocapnic hypoxia, iso-oxic hypercapnia, and 20 min of isocapnic hypoxia (arterial Po2 = 50 mmHg). Blood gas alterations were achieved with dynamic end-tidal forcing. When expressed as a function of the logarithm of oxygen partial pressure, ventilatory sensitivity to hypoxia was not different between groups. However, there was a significant difference when expressed as a function of S a O 2 . Conversely, the rise in heart rate was blunted in HAH subjects when expressed as a function of partial pressure but similar when expressed as a function of S a O 2 . Ventilatory sensitivity to hypercapnia was not different between groups. During sustained isocapnic hypoxia, the rise in minute ventilation was similar between groups; however, heart rate was significantly greater in the controls during 3 to 9 min of exposure. Our results support the notion that oxygen tension, not content, alters cellular Po2 in the chemosensors and drives the hypoxic ventilatory response. Our study suggests that in addition to oxygen partial pressure, oxygen content may also influence the heart rate response to hypoxia.NEW & NOTEWORTHY We dissociated the effects of oxygen content and pressure of cardiorespiratory regulation studying individuals with high-affinity hemoglobin (HAH). During hypoxia, the ventilatory response, expressed as a function of oxygen tension, was similar between HAH variants and controls; however, the rise in heart rate was blunted in the variants. Our work supports the notion that the hypoxic ventilatory response is regulated by oxygen tension, whereas cardiovascular regulation may be influenced by arterial oxygen content and tension.
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Affiliation(s)
- Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Sarah E Baker
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Chad C Wiggins
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Glenn M Stewart
- Department of Cardiovascular Disease, Mayo Clinic, Rochester, Minnesota
| | - Pavol Sajgalik
- Department of Cardiovascular Disease, Mayo Clinic, Rochester, Minnesota
| | - John R A Shepherd
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Shelly K Roberts
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Tuhin K Roy
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Timothy B Curry
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - James D Hoyer
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Jennifer L Oliveira
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Glen E Foster
- School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Michael J Joyner
- Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
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Teppema LJ, Boulet LM, Hackett HK, Dominelli PB, Cheyne WS, Dominelli GS, Swenson ER, Foster GE. Influence of methazolamide on the human control of breathing: A comparison to acetazolamide. Exp Physiol 2019; 105:293-301. [PMID: 31595565 DOI: 10.1113/ep088058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 10/04/2019] [Indexed: 01/15/2023]
Abstract
NEW FINDINGS What is the central question of this study? Acetazolamide and methazolamide both reduce hypoxic pulmonary vasoconstriction equally, but methazolamide does not impair skeletal muscle function. The effect of methazolamide on respiratory control in humans is not yet known. What is the main finding and its importance? Similar to acetazolamide after chronic oral administration, methazolamide causes a metabolic acidosis and shifts the ventilatory CO2 response curve leftwards without reducing O2 sensitivity. The change in ventilation over the change in log P O 2 provides a more accurate measure of hypoxic sensitivity than the change in ventilation over the change in arterial oxyhaemoglobin saturation. ABSTRACT Acetazolamide is used to prevent/treat acute mountain sickness and both central and obstructive sleep apnoea. Methazolamide, like acetazolamide, reduces hypoxic pulmonary vasoconstriction, but has fewer side-effects, including less impairment of skeletal muscle function. Given that the effects of methazolamide on respiratory control in humans are unknown, we compared the effects of oral methazolamide and acetazolamide on ventilatory control and determined the ventilation-log P O 2 relationship in humans. In a double-blind, placebo-controlled, randomized cross-over design, we studied the effects of acetazolamide (250 mg three times daily), methazolamide (100 mg twice daily) and placebo in 14 young male subjects who were exposed to 7 min of normoxic hypercapnia and to three levels of eucapnia and hypercapnic hypoxia. With placebo, methazolamide and acetazolamide, the CO2 sensitivities were 2.39 ± 1.29, 3.27 ± 1.82 and 2.62 ± 1.79 l min-1 mmHg-1 (n.s.) and estimated apnoeic thresholds 32 ± 3, 28 ± 3 and 26 ± 3 mmHg, respectively (P < 0.001, placebo versus methazolamide and acetazolamide). The relationship between ventilation ( V ̇ I ) and log P O 2 (using arterialized venous P O 2 in hypoxia) was linear, and neither agent influenced the relationship between hypoxic sensitivity ( Δ V ̇ I / Δ log P O 2 ) and arterial [H+ ]. Using Δ V ̇ I / Δ log P O 2 rather than Δ V ̇ I /Δ arterial oxyhaemoglobin saturation enables a more accurate estimation of oxygenation and ventilatory control in metabolic acidosis/alkalosis when right- or leftward shifts of the oxyhaemoglobin saturation curve occur. Given that acetazolamide and methazolamide have similar effects on ventilatory control, methazolamide might be preferred for indications requiring the use of a carbonic anhydrase inhibitor, avoiding some of the negative side-effects of acetazolamide.
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Affiliation(s)
- Luc J Teppema
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Heather K Hackett
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Paolo B Dominelli
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada.,Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada
| | - William S Cheyne
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Giulio S Dominelli
- Southern Medical Program, University of British Columbia, Kelowna, BC, Canada
| | - Erik R Swenson
- Division of Pulmonary & Critical Care Medicine, VA Puget Sound Health Care System, University of Washington, Seattle, WA, USA
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
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Zuo L, Simpson A, Dominelli PB, Henderson WR. Commentaries on Viewpoint: Looking beyond macroventilatory parameters and rethinking ventilator-induced lung injury. J Appl Physiol (1985) 2019; 124:1219. [PMID: 29745824 DOI: 10.1152/japplphysiol.00069.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Li Zuo
- School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, Columbus, Ohio
| | - Alicia Simpson
- School of Health and Rehabilitation Sciences, The Ohio State University College of Medicine, Columbus, Ohio
| | | | - William R. Henderson
- Division of Critical Care Medicine, University of British Columbia, Vancouver, BC, Canada
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46
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Molgat-Seon Y, Dominelli PB, Guenette JA, Sheel AW. Modelling the effects of age and sex on the resistive and viscoelastic components of the work of breathing during exercise. Exp Physiol 2019; 104:1737-1745. [PMID: 31408911 DOI: 10.1113/ep087956] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 08/12/2019] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the effect of age and sex on the resistive and viscoelastic components of work of breathing (Wb ) during exercise? What is the main finding and its importance? The resistive and viscoelastic components of Wb were higher in older adults, regardless of sex. The resistive, but not viscoelastic, component of Wb was higher in females than in males, regardless of age. These findings contribute to improving our understanding of the effects of ageing and sex on the mechanical ventilatory response to exercise. ABSTRACT Healthy ageing and biological sex each affect the work of breathing (Wb ) for a given minute ventilation ( V ̇ E ). Age-related structural changes to the respiratory system lead to an increase in both the resistive and viscoelastic components of Wb ; however, it is unclear whether healthy ageing differentially alters the mechanics of breathing in males and females. We analysed data from 22 older (60-80 years, n = 12 females) and 22 younger (20-30 years, n = 11 females) males and females that underwent an incremental cycle exercise test to exhaustion. V ̇ E and Wb were assessed at rest and throughout exercise. Wb - V ̇ E data for each participant were fitted to a non-linear equation (i.e. Wb = a V ̇ E 3 + b V ̇ E 2 ) that partitions Wb into resistive (i.e. a V ̇ E 3 ) and viscoelastic (i.e. b V ̇ E 2 ) components. We then modelled the effects of healthy ageing and biological sex on each component of Wb . Overall, the model fit was excellent (r2 : 0.99 ± 0.01). There was a significant main effect of age and sex on the resistive component of Wb (both P < 0.05), and a significant main effect of age (P < 0.001), but not sex (P = 0.309), on the viscoelastic component of Wb . No significant interactions between age and sex on a V ̇ E 3 or b V ̇ E 2 were noted (both P > 0.05). Our findings indicate that during exercise: (i) the higher total Wb in females relative to males is due to a higher resistive, but not viscoelastic, component of Wb , and (ii) regardless of sex, the higher Wb in older adults relative to younger adults is due to higher resistive and viscoelastic components of Wb .
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Affiliation(s)
- Yannick Molgat-Seon
- Department of Kinesiology and Applied Health, Gupta Faculty of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, MB, Canada.,Centre for Heart and Lung Innovation, St Paul's Hospital, Vancouver, BC, Canada.,Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.,School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Jordan A Guenette
- Centre for Heart and Lung Innovation, St Paul's Hospital, Vancouver, BC, Canada.,Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.,School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC, Canada
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Molgat-Seon Y, Dominelli PB, Peters CM, Guenette JA, Sheel AW, Gladstone IM, Lovering AT, Duke JW. Analysis of maximal expiratory flow-volume curves in adult survivors of preterm birth. Am J Physiol Regul Integr Comp Physiol 2019; 317:R588-R596. [PMID: 31433666 DOI: 10.1152/ajpregu.00114.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Adult survivors of very preterm (≤32 wk gestational age) birth without (PRE) and with bronchopulmonary dysplasia (BPD) have variable degrees of airflow obstruction at rest. Assessment of the shape of the maximal expiratory flow-volume (MEFV) curve in PRE and BPD may provide information concerning their unique pattern of airflow obstruction. The purposes of the present study were to 1) quantitatively assess the shape of the MEFV curve in PRE, BPD, and healthy adults born at full-term (CON), 2) identify where along the MEFV curve differences in shape existed between groups, and 3) determine the association between an index of MEFV curve shape and characteristics of preterm birth (i.e., gestational age, mass at birth, duration of oxygen therapy) in PRE and BPD. To do so, we calculated the average slope ratio (SR) throughout the effort-independent portion of the MEFV curve and at increments of 5% of forced vital capacity (FVC) between 20 and 80% of FVC in PRE (n = 19), BPD (n = 25), and CON (n = 20). We found that average SR was significantly higher in PRE (1.34 ± 0.35) and BPD (1.33 ± 0.45) compared with CON (1.03 ± 0.22; both P < 0.05) but similar between PRE and BPD (P = 0.99). Differences in SR between groups occurred early in expiration (i.e., 20-30% of FVC). There was no association between SR and characteristics of preterm birth in PRE and BPD groups (all P > 0.05). The mechanism(s) of increased SR during early expiration in PRE/BPD relative to CON is unknown but may be due to differences in the structural and mechanical properties of the airways.
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Affiliation(s)
- Yannick Molgat-Seon
- Department of Kinesiology and Applied Health, University of Winnipeg, Winnipeg, Manitoba, Canada.,Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart and Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Carli M Peters
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jordan A Guenette
- Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart and Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada.,School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Igor M Gladstone
- Oregon Health and Sciences University, Department of Paediatrics, Portland, Oregon
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Joseph W Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
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Shepherd JRA, Dominelli PB, Roy TK, Secomb TW, Hoyer JD, Oliveira JL, Joyner MJ. Modelling the relationships between haemoglobin oxygen affinity and the oxygen cascade in humans. J Physiol 2019; 597:4193-4202. [PMID: 31290158 DOI: 10.1113/jp277591] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 07/08/2019] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Haemoglobin affinity is an integral concept in exercise physiology that impacts oxygen uptake, delivery and consumption. How chronic alterations in haemoglobin affinity impact physiology is unknown. Using human haemoglobin variants, we demonstrate that the affinity of haemoglobin for oxygen is highly correlated with haemoglobin concentration. Using the Fick equation, we model how altered haemoglobin affinity and the associated haemoglobin concentration influences oxygen consumption at rest and during exercise via alterations in cardiac output and mixed-venous P O 2 . The combination of low oxygen affinity haemoglobin and reduced haemoglobin concentration seen in vivo may be unable to support oxygen uptake during moderate or heavy exercise. ABSTRACT The physiological implications, with regard to exercise, of altered haemoglobin affinity for oxygen are not fully understood. Data from the Mayo Clinic Laboratories database of rare human haemoglobin variants reveal a strong inverse correlation (r = -0.82) between blood haemoglobin concentration and P50 , an index of oxygen affinity [Hb = -0.3135(P50 ) + 23.636]. In the present study, observed P50 values for high, normal and low oxygen-affinity haemoglobin variants (13, 26 and 39 mmHg) and corresponding haemoglobin concentrations (19.5, 15.5 and 11.4 g dL-1 respectively) are used to model oxygen consumption as a fraction of delivery at rest ( V ̇ O 2 = 0.25 L min-1 , cardiac output = 5.70 L min-1 ) and during exercise ( V ̇ O 2 = 2.75 L min-1 , cardiac output = 18.9 l min-1 ). With high-affinity haemoglobin, the model shows that normal levels of oxygen consumption can be achieved at rest and during exercise at the assumed cardiac output levels, with reduced oxygen extraction both at rest (16.8% high affinity vs. 21.7% normal) and during exercise (55.8% high affinity vs. 72.2% normal). With low-affinity haemoglobin, which predicts low haemoglobin concentration, oxygen consumption at rest can be sustained with the assumed cardiac output, with increased oxygen extraction (31.1% low affinity vs. 21.7% normal). However, exercise at 2.75 l min-1 cannot be achieved with the assumed cardiac output, even with 100% oxygen extraction. In conclusion, the model indicates chronic alterations in P50 associate directly with Hb concentration, highlighting that human Hb variants can serve as 'experiments of nature' to address fundamental hypotheses on oxygen transport and exercise.
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Affiliation(s)
- John R A Shepherd
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Paolo B Dominelli
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Kinesiology, University of Waterloo, Waterloo, ON, USA
| | - Tuhin K Roy
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
| | - Timothy W Secomb
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - James D Hoyer
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Jennifer L Oliveira
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Michael J Joyner
- Department of Anesthesiology & Perioperative Medicine, Mayo Clinic, Rochester, MN, USA
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Sheel AW, Dominelli PB. Breathing during exercise: There is no such thing as a free lunch. Exp Physiol 2019; 104:1333-1334. [PMID: 31325338 DOI: 10.1113/ep087922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 07/17/2019] [Indexed: 11/08/2022]
Affiliation(s)
- A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
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Abstract
Exercise-induced arterial hypoxemia (EIAH) is characterized by the decrease in arterial oxygen tension and oxyhemoglobin saturation during dynamic aerobic exercise. Since the time of the initial observations, our knowledge and understanding of EIAH has grown, but many unknowns remain. The purpose of this review is to provide an update on recent findings, highlight areas of disagreement, and identify where information is lacking. Specifically, this review will place emphasis on (i) the occurrence of EIAH during submaximal exercise, (ii) whether there are sex differences in the development and severity of EIAH, and (iii) unresolved questions and future directions.
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Affiliation(s)
- Paolo B. Dominelli
- Department of Anesthesiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - A. William Sheel
- School of Kinesiology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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