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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] [Abstract] [Key Words] [MESH Headings] [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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2
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Haverkamp HC, Balmain BN. Ventilatory Responses to Exercise by Age, Sex, and Health Status. Curr Sports Med Rep 2024; 23:79-85. [PMID: 38437493 DOI: 10.1249/jsr.0000000000001149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
ABSTRACT An understanding of the normal pulmonary responses to incremental exercise is requisite for appropriate interpretation of findings from clinical exercise testing. The purpose of this review is to provide concrete information to aid the interpretation of the exercise ventilatory response in both healthy and diseased populations. We begin with an overview of the normal exercise ventilatory response to incremental exercise in the healthy, normally trained young-to-middle aged adult male. The exercise ventilatory responses in two nonpatient populations (females, elderly) are then juxtaposed with the responses in healthy males. The review concludes with overviews of the exercise ventilatory responses in four patient populations (obesity, chronic obstructive pulmonary disease, asthma, congestive heart failure). Again, we use the normal response in healthy adults as the framework for interpreting the responses in the clinical groups. For each healthy and clinical population, recent, impactful research findings will be presented.
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Affiliation(s)
- Hans Christian Haverkamp
- Department of Nutrition and Exercise Physiology, Elson S. Floyd College of Medicine, Washington State University-Spokane Health Sciences, Spokane, WA
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Brotto AR, Phillips DB, Rowland SD, Moore LE, Wong E, Stickland MK. Reduced tidal volume-inflection point and elevated operating lung volumes during exercise in females with well-controlled asthma. BMJ Open Respir Res 2023; 10:e001791. [PMID: 38135461 DOI: 10.1136/bmjresp-2023-001791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 12/01/2023] [Indexed: 12/24/2023] Open
Abstract
INTRODUCTION Individuals with asthma breathe at higher operating lung volumes during exercise compared with healthy individuals, which contributes to increased exertional dyspnoea. In health, females are more likely to develop exertional dyspnoea than males at a given workload or ventilation, and therefore, it is possible that females with asthma may develop disproportional dyspnoea on exertion. The purpose of this study was to compare operating lung volume and dyspnoea responses during exercise in females with and without asthma. METHODS Sixteen female controls and 16 females with asthma were recruited for the study along with 16 male controls and 16 males with asthma as a comparison group. Asthma was confirmed using American Thoracic Society criteria. Participants completed a cycle ergometry cardiopulmonary exercise test to volitional exhaustion. Inspiratory capacity manoeuvres were performed to estimate inspiratory reserve volume (IRV) and dyspnoea was evaluated using the Modified Borg Scale. RESULTS Females with asthma exhibited elevated dyspnoea during submaximal exercise compared with female controls (p<0.05). Females with asthma obtained a similar IRV and dyspnoea at peak exercise compared with healthy females despite lower ventilatory demand, suggesting mechanical constraint to tidal volume (VT) expansion. VT-inflection point was observed at significantly lower ventilation and V̇O2 in females with asthma compared with female controls. Forced expired volume in 1 s was significantly associated with VT-inflection point in females with asthma (R2=0.401; p<0.01) but not female controls (R2=0.002; p=0.88). CONCLUSION These results suggest that females with asthma are more prone to experience exertional dyspnoea, secondary to dynamic mechanical constraints during submaximal exercise when compared with females without asthma.
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Affiliation(s)
- Andrew R Brotto
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Devin B Phillips
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- School of Kinesiology and Health Science, Faculty of Health, York University, Toronto, Ontario, Canada
| | - Samira D Rowland
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Linn E Moore
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Eric Wong
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Michael K Stickland
- Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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Haverkamp HC, Luu P, DeCato TW, Petrics G. Artificial neural network identification of exercise expiratory flow-limitation in adults. Sci Rep 2023; 13:17247. [PMID: 37821579 PMCID: PMC10567738 DOI: 10.1038/s41598-023-44331-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/06/2023] [Indexed: 10/13/2023] Open
Abstract
Identification of ventilatory constraint is a key objective of clinical exercise testing. Expiratory flow-limitation (EFL) is a well-known type of ventilatory constraint. However, EFL is difficult to measure, and commercial metabolic carts do not readily identify or quantify EFL. Deep machine learning might provide a new approach for identifying EFL. The objective of this study was to determine if a convolutional neural network (CNN) could accurately identify EFL during exercise in adults in whom baseline airway function varied from normal to mildly obstructed. 2931 spontaneous exercise flow-volume loops (eFVL) were placed within the baseline maximal expiratory flow-volume curves (MEFV) from 22 adults (15 M, 7 F; age, 32 yrs) in whom lung function varied from normal to mildly obstructed. Each eFVL was coded as EFL or non-EFL, where EFL was defined by eFVLs with expired airflow meeting or exceeding the MEFV curve. A CNN with seven hidden layers and a 2-neuron softmax output layer was used to analyze the eFVLs. Three separate analyses were conducted: (1) all subjects (n = 2931 eFVLs, [GRALL]), (2) subjects with normal spirometry (n = 1921 eFVLs [GRNORM]), (3) subjects with mild airway obstruction (n = 1010 eFVLs, [GRLOW]). The final output of the CNN was the probability of EFL or non-EFL in each eFVL, which is considered EFL if the probability exceeds 0.5 or 50%. Baseline forced expiratory volume in 1 s/forced vital capacity was 0.77 (94% predicted) in GRALL, 0.83 (100% predicted) in GRNORM, and 0.69 (83% predicted) in GRLOW. CNN model accuracy was 90.6, 90.5, and 88.0% in GRALL, GRNORM and GRLOW, respectively. Negative predictive value (NPV) was higher than positive predictive value (PPV) in GRNORM (93.5 vs. 78.2% for NPV vs. PPV). In GRLOW, PPV was slightly higher than NPV (89.5 vs. 84.5% for PPV vs. NPV). A CNN performed very well at identifying eFVLs with EFL during exercise. These findings suggest that deep machine learning could become a viable tool for identifying ventilatory constraint during clinical exercise testing.
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Affiliation(s)
- Hans Christian Haverkamp
- Department of Nutrition and Exercise Physiology, Washington State University-Spokane Health Sciences, Elson S. Floyd College of Medicine, 412 E. Spokane Falls Blvd., Spokane, WA, 99202-2131, USA.
| | - Peter Luu
- Department of Nutrition and Exercise Physiology, Washington State University-Spokane Health Sciences, Elson S. Floyd College of Medicine, 412 E. Spokane Falls Blvd., Spokane, WA, 99202-2131, USA
| | - Thomas W DeCato
- Department of Medical Education and Clinical Sciences, Washington State University-Spokane Health Sciences, Elson S. Floyd College of Medicine, Spokane, WA, USA
- Division of Respiratory & Critical Care Physiology & Medicine, Harbor-UCLA Medical Center and the Lundquist Institute for Biomedical Innovation, Torrance, CA, USA
| | - Gregory Petrics
- Department of Mathematics, Vermont State University-Johnson, Johnson, VT, USA
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Franceschi E, Drick N, Fuge J, Santus P, Fischer B, Kayser M, Welte T, Suhling H. The impact of anti-eosinophilic therapy on exercise capacity and inspiratory muscle strength in patients with severe asthma. ERJ Open Res 2023; 9:00341-2022. [PMID: 36949965 PMCID: PMC10026001 DOI: 10.1183/23120541.00341-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 11/09/2022] [Indexed: 03/18/2023] Open
Abstract
Introduction Exercise limitation is frequently described among asthmatic patients and could be related to different mechanisms of the pulmonary, cardiovascular and muscular systems. Despite this, cardiopulmonary exercise testing (CPET) does not have an established role in the management of severe asthma. The aim of our study was to investigate the role of CPET and inspiratory pressure measurement in exercise capacity and muscle strength in severe asthmatic patients treated with anti-IL-5 therapy. Methods A monocentric observational study was conducted at Hanover Medical School, Germany, from April 2018 to June 2019. Patients affected by severe asthma treated with either mepolizumab or benralizumab were included. All patients underwent CPET before the initiation of antibody therapy and after 3 months, and follow-up visits were scheduled at 3, 6 and 12 months with plethysmography, inspiratory pressure measurement and blood gas analysis. Results 14 patients were enrolled: 10 (71.4%) females, median age 52 years (IQR 47-61). Seven patients were treated with benralizumab, seven with mepolizumab. Oxygen uptake (V'O2 peak) did not change significantly after 3 months of antibody treatment, while the mean value of the breathing reserve exhaustion reduced significantly from 78% to 60% (p=0.004). Whereas at baseline seven patients depleted the breathing reserve and two of them experienced oxygen desaturation during exercise, at 3 months no one presented any desaturation or breathing reserve exhaustion. The inspiratory pressure remained unchanged before and after the antibody therapy. Conclusion CPET could show hints of alveolar recruitment and ventilatory efficiency in severe asthma patients treated with antibody therapy.
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Affiliation(s)
- Elisa Franceschi
- Department of Respiratory Diseases, Ospedale Luigi Sacco, Polo Universitario, ASST Fatebenefratelli-Sacco, Milan, Italy
- Department of Biomedical and Clinical Sciences (DIBIC), Università degli Studi di Milano, Milan, Italy
- Corresponding author: Elisa Franceschi ()
| | - Nora Drick
- Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | - Jan Fuge
- Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL) , Hannover, Germany
| | - Pierachille Santus
- Department of Respiratory Diseases, Ospedale Luigi Sacco, Polo Universitario, ASST Fatebenefratelli-Sacco, Milan, Italy
- Department of Biomedical and Clinical Sciences (DIBIC), Università degli Studi di Milano, Milan, Italy
| | - Bettina Fischer
- Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | - Moritz Kayser
- Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | - Tobias Welte
- Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL) , Hannover, Germany
| | - Hendrik Suhling
- Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
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Rossman MJ, Petrics G, Klansky A, Craig K, Irvin CG, Haverkamp HC. Exercise-induced Bronchodilation Equalizes Exercise Ventilatory Mechanics despite Variable Baseline Airway Function in Asthma. Med Sci Sports Exerc 2022; 54:258-266. [PMID: 34559730 PMCID: PMC8892975 DOI: 10.1249/mss.0000000000002793] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE We quantified the magnitude of exercise-induced bronchodilation in adult asthmatics under conditions of narrowed and dilated airways. We then assessed the effect of the bronchodilation on ventilatory capacity and the extent of ventilatory limitation during exercise. METHODS Eleven asthmatics completed three exercise bouts on a cycle ergometer. Exercise was preceded by no treatment (trialCON), inhaled β2 agonist (trialBD), or a eucapnic voluntary hyperpnea challenge (trialBC). Maximal expiratory flow-volume maneuvers (MEFV) were performed before and within 40 s of exercise cessation. Exercise tidal flow-volume loops were placed within the preexercise and postexercise MEFV curve and used to determine expiratory flow limitation and maximum ventilatory capacity (V˙ECap). RESULTS Preexercise airway function was different among the trials (forced expiratory volume 1 s during trialCON, trialBD, and trialBC = 3.3 ± 0.8 L, 3.8 ± 0.8 L, and 2.9 ± 0.8 L, respectively; P < 0.05). Maximal expired airflow increased with exercise during all three trials, but the increase was greatest during trialBC (delta forced expiratory volume 1 s during trialCON, trialBD, and trialBC = +12.2% ± 13.1%, +5.2% ± 5.7%, +28.1% ± 15.7%). Thus, the extent of expiratory flow limitation decreased, and V˙ECap increased, when the postexercise MEFV curve was used. During trialCON and trialBC, actual exercise ventilation exceeded V˙ECap calculated with the preexercise MEFV curve in seven and nine subjects, respectively. CONCLUSIONS These findings demonstrate the critical importance of exercise bronchodilation in the asthmatic with narrowed airways. Of clinical relevance, the results also highlight the importance of assessing airway function during or immediately after exercise in asthmatic persons; otherwise, mechanical limitations to exercise ventilation will be overestimated.
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Affiliation(s)
- Matthew J Rossman
- Department of Integrative Physiology, University of Colorado-Boulder, Boulder, CO
| | - Greg Petrics
- Department of Environmental and Health Sciences, Northern Vermont University-Johnson, Johnson, VT
| | - Andrew Klansky
- Department of Environmental and Health Sciences, Northern Vermont University-Johnson, Johnson, VT
| | - Kasie Craig
- Department of Environmental and Health Sciences, Northern Vermont University-Johnson, Johnson, VT
| | - Charles G Irvin
- Departments of Medicine and Biophysics Pulmonary and Critical Care Medicine, University of Vermont, Burlington, VT
| | - Hans Christian Haverkamp
- Department of Nutrition and Exercise Physiology, Elson S. Floyd College of Medicine, Washington State University-Spokane Health Sciences, Spokane, WA
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Dempsey JA, Neder JA, Phillips DB, O'Donnell DE. The physiology and pathophysiology of exercise hyperpnea. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:201-232. [PMID: 35965027 DOI: 10.1016/b978-0-323-91534-2.00001-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In health, the near-eucapnic, highly efficient hyperpnea during mild-to-moderate intensity exercise is driven by three obligatory contributions, namely, feedforward central command from supra-medullary locomotor centers, feedback from limb muscle afferents, and respiratory CO2 exchange (V̇CO2). Inhibiting each of these stimuli during exercise elicits a reduction in hyperpnea even in the continuing presence of the other major stimuli. However, the relative contribution of each stimulus to the hyperpnea remains unknown as does the means by which V̇CO2 is sensed. Mediation of the hyperventilatory response to exercise in health is attributed to the multiple feedback and feedforward stimuli resulting from muscle fatigue. In patients with COPD, diaphragm EMG amplitude and its relation to ventilatory output are used to decipher mechanisms underlying the patients' abnormal ventilatory responses, dynamic lung hyperinflation and dyspnea during exercise. Key contributions to these exercise-limiting responses across the spectrum of COPD severity include high dead space ventilation, an excessive neural drive to breathe and highly fatigable limb muscles, together with mechanical constraints on ventilation. Major controversies concerning control of exercise hyperpnea are discussed along with the need for innovative research to uncover the link of metabolism to breathing in health and disease.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, United States.
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
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Collins SÉ, Phillips DB, Brotto AR, Rampuri ZH, Stickland MK. Ventilatory efficiency in athletes, asthma and obesity. Eur Respir Rev 2021; 30:30/161/200206. [PMID: 34289980 DOI: 10.1183/16000617.0206-2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/16/2020] [Indexed: 11/05/2022] Open
Abstract
During submaximal exercise, minute ventilation (V' E) increases in proportion to metabolic rate (i.e. carbon dioxide production (V' CO2 )) to maintain arterial blood gas homeostasis. The ratio V' E/V' CO2 , commonly termed ventilatory efficiency, is a useful tool to evaluate exercise responses in healthy individuals and patients with chronic disease. Emerging research has shown abnormal ventilatory responses to exercise (either elevated or blunted V' E/V' CO2 ) in some chronic respiratory and cardiovascular conditions. This review will briefly provide an overview of the physiology of ventilatory efficiency, before describing the ventilatory responses to exercise in healthy trained endurance athletes, patients with asthma, and patients with obesity. During submaximal exercise, the V' E/V' CO2 response is generally normal in endurance-trained individuals, patients with asthma and patients with obesity. However, in endurance-trained individuals, asthmatics who demonstrate exercise induced-bronchoconstriction, and morbidly obese individuals, the V' E/V' CO2 can be blunted at maximal exercise, likely because of mechanical ventilatory constraint.
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Affiliation(s)
- Sophie É Collins
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University, Kingston, Canada
| | - Andrew R Brotto
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Zahrah H Rampuri
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada
| | - Michael K Stickland
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.,G.F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, Canada
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Dempsey JA, La Gerche A, Hull JH. Is the healthy respiratory system built just right, overbuilt, or underbuilt to meet the demands imposed by exercise? J Appl Physiol (1985) 2020; 129:1235-1256. [PMID: 32790594 DOI: 10.1152/japplphysiol.00444.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In the healthy, untrained young adult, a case is made for a respiratory system (airways, pulmonary vasculature, lung parenchyma, respiratory muscles, and neural ventilatory control system) that is near ideally designed to ensure a highly efficient, homeostatic response to exercise of varying intensities and durations. Our aim was then to consider circumstances in which the intra/extrathoracic airways, pulmonary vasculature, respiratory muscles, and/or blood-gas distribution are underbuilt or inadequately regulated relative to the demands imposed by the cardiovascular system. In these instances, the respiratory system presents a significant limitation to O2 transport and contributes to the occurrence of locomotor muscle fatigue, inhibition of central locomotor output, and exercise performance. Most prominent in these examples of an "underbuilt" respiratory system are highly trained endurance athletes, with additional influences of sex, aging, hypoxic environments, and the highly inbred equine. We summarize by evaluating the relative influences of these respiratory system limitations on exercise performance and their impact on pathophysiology and provide recommendations for future investigation.
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Affiliation(s)
- Jerome A Dempsey
- John Robert Sutton Professor of Population Health Sciences, John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Andre La Gerche
- Clinical Research Domain, Baker Heart and Diabetes Institute, Melbourne, Australia.,National Center for Sports Cardiology, St. Vincent's Hospital, Melbourne, Fitzroy, Australia
| | - James H Hull
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom.,Institute of Sport, Exercise and Health (ISEH), University College London, United Kingdom
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Francescato MP, Canciani M, Cettolo V. Interchangeability between two breath-by-breath O 2 uptake calculation algorithms in asthmatic and healthy volunteers. Eur J Appl Physiol 2020; 120:1417-1428. [PMID: 32306150 DOI: 10.1007/s00421-020-04374-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 04/09/2020] [Indexed: 10/24/2022]
Abstract
INTRODUCTION The interchangeability analysis has been recently proposed to objectively assess whether a newly developed measurement tool can substitute the older ones; this analysis assumes that the measures yielded by the compared tools should differ less than a maximum acceptable value. We aimed to assess the interchangeability rate (IR) of the breath-by-breath O2 uptake data calculated with the "Independent breath" (IND) and the "Expiration-only" (EXP) algorithms. METHODS Oxygen, carbon dioxide fractions, and ventilatory flow were recorded continuously over 26 min in 18 asthmatic and 20 well-matched healthy volunteers at rest, during cycling, and recovery; oxygen uptake (V'O2) was calculated with the two algorithms under comparison. Coefficients of variation (CVs) of all the steady-state condition were modeled as a function of the average V'O2 values and IR was calculated accordingly. RESULTS CVs were significantly greater in the asthmatic volunteers (F = 5.97, p < 0.05), being lower for IND compared to EXP (F > 7.04, p < 0.02). CVs decreased as a function of the reciprocal of the square root of the average V'O2. The IR, calculated on the basis of this relationship, was not significantly different in the two groups of volunteers (F = 0.77, p = 0.385); taking as reference method the IND, or EXP algorithms, the IR values were significantly different (F = 58.6, p < 0.001), amounting to 97.4 ± 2.2% or to 98.2 ± 1.7%, respectively. CONCLUSION The relative noise of V'O2 was greater in the asthmatic volunteers compared to the healthy ones and was lower for IND compared to EXP. The interchangeability analysis suggested that IND might be a better substitute for EXP than the opposite.
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Affiliation(s)
| | - Mario Canciani
- Allergology and Pulmonology Clinic and Laboratory, ALPI Association, Udine, Italy
| | - Valentina Cettolo
- Department of Medicine, University of Udine, P.le Kolbe 4, 33100, Udine, Italy
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11
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Boutou AK, Daniil Z, Pitsiou G, Papakosta D, Kioumis I, Stanopoulos I. Cardiopulmonary exercise testing in patients with asthma: What is its clinical value? Respir Med 2020; 167:105953. [PMID: 32280032 DOI: 10.1016/j.rmed.2020.105953] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 03/29/2020] [Accepted: 03/31/2020] [Indexed: 01/28/2023]
Abstract
Asthma is one of the most common respiratory disorders, characterized by fully or largely reversible airflow limitation. Asthma symptoms can be triggered or magnified during exertion, while physical activity limitation is often present among asthmatic patients. Cardiopulmonary exercise testing (CPET) is a dynamic, non-invasive technique which provides a thorough assessment of exercise physiology, involving the integrative assessment of cardiopulmonary, neuromuscular and metabolic responses during exercise. This review summarizes current evidence regarding the utility of CPET in the diagnostic work-up, functional evaluation and therapeutic intervention among patients with asthma, highlighting its potential role for thorough patient assessment and physician clinical desicion-making.
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Affiliation(s)
- Afroditi K Boutou
- Department of Respiratory Medicine, "G. Papanikolaou" Hospital, Thessaloniki, Greece.
| | - Zoi Daniil
- Department of Respiratory Medicine, Faculty of Medicine, University of Thessaly, Larissa, Greece
| | - Georgia Pitsiou
- Department of Respiratory Failure, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Despoina Papakosta
- Department of Respiratory Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Ioannis Kioumis
- Department of Respiratory Failure, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Ioannis Stanopoulos
- Department of Respiratory Failure, Aristotle University of Thessaloniki, Thessaloniki, Greece
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12
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Understanding the total airway response to exercise: current perspectives and future challenges. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.05.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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13
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O'Donnell DE, Elbehairy AF, Berton DC, Domnik NJ, Neder JA. Advances in the Evaluation of Respiratory Pathophysiology during Exercise in Chronic Lung Diseases. Front Physiol 2017; 8:82. [PMID: 28275353 PMCID: PMC5319975 DOI: 10.3389/fphys.2017.00082] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/30/2017] [Indexed: 11/13/2022] Open
Abstract
Dyspnea and exercise limitation are among the most common symptoms experienced by patients with various chronic lung diseases and are linked to poor quality of life. Our understanding of the source and nature of perceived respiratory discomfort and exercise intolerance in chronic lung diseases has increased substantially in recent years. These new mechanistic insights are the primary focus of the current review. Cardiopulmonary exercise testing (CPET) provides a unique opportunity to objectively evaluate the ability of the respiratory system to respond to imposed incremental physiological stress. In addition to measuring aerobic capacity and quantifying an individual's cardiac and ventilatory reserves, we have expanded the role of CPET to include evaluation of symptom intensity, together with a simple "non-invasive" assessment of relevant ventilatory control parameters and dynamic respiratory mechanics during standardized incremental tests to tolerance. This review explores the application of the new advances in the clinical evaluation of the pathophysiology of exercise intolerance in chronic obstructive pulmonary disease (COPD), chronic asthma, interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH). We hope to demonstrate how this novel approach to CPET interpretation, which includes a quantification of activity-related dyspnea and evaluation of its underlying mechanisms, enhances our ability to meaningfully intervene to improve quality of life in these pathologically-distinct conditions.
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Affiliation(s)
- Denis E. O'Donnell
- Division of Respiratory Medicine, Department of Medicine, Queen's University and Kingston General HospitalKingston, ON, Canada
| | - Amany F. Elbehairy
- Division of Respiratory Medicine, Department of Medicine, Queen's University and Kingston General HospitalKingston, ON, Canada
- Department of Chest Diseases, Faculty of Medicine, Alexandria UniversityAlexandria, Egypt
| | - Danilo C. Berton
- Division of Respiratory Medicine, Department of Medicine, Queen's University and Kingston General HospitalKingston, ON, Canada
| | - Nicolle J. Domnik
- Division of Respiratory Medicine, Department of Medicine, Queen's University and Kingston General HospitalKingston, ON, Canada
| | - J. Alberto Neder
- Division of Respiratory Medicine, Department of Medicine, Queen's University and Kingston General HospitalKingston, ON, Canada
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14
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Lu KD, Manoukian K, Radom-Aizik S, Cooper DM, Galant SP. Obesity, Asthma, and Exercise in Child and Adolescent Health. Pediatr Exerc Sci 2016; 28:264-274. [PMID: 26618409 PMCID: PMC5904022 DOI: 10.1123/pes.2015-0122] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Obesity increases the risk of asthma throughout life but the underlying mechanisms linking these all too common threats to child health are poorly understood. Acute bouts of exercise, aerobic fitness, and levels of physical activity clearly play a role in the pathogenesis and/or management of both childhood obesity and asthma. Moreover, both obesity and physical inactivity are associated with asthma symptomatology and response to therapy (a particularly challenging feature of obesity-related asthma). In this article, we review current understandings of the link between physical activity, aerobic fitness and the asthma-obesity link in children and adolescents (e.g., the impact of chronic low-grade inflammation, lung mechanics, and direct effects of metabolic health on the lung). Gaps in our knowledge regarding the physiological mechanisms linking asthma, obesity and exercise are often compounded by imprecise estimations of adiposity and challenges of assessing aerobic fitness in children. Addressing these gaps could lead to practical interventions and clinical approaches that could mitigate the profound health care crisis of the increasing comorbidity of asthma, physical inactivity, and obesity in children.
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Affiliation(s)
- Kim D. Lu
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
| | | | - Shlomit Radom-Aizik
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
| | - Dan M. Cooper
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
| | - Stanley P. Galant
- Pediatric Exercise and Genomics Research Center, Department of Pediatrics, UC Irvine School of Medicine
- Children’s Hospital of Orange County, Orange, California
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15
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Koch S, Karacabeyli D, Galts C, MacInnis MJ, Sporer BC, Koehle MS. Effects of inhaled bronchodilators on lung function and cycling performance in female athletes with and without exercise-induced bronchoconstriction. J Sci Med Sport 2015; 18:607-12. [DOI: 10.1016/j.jsams.2014.07.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/18/2014] [Accepted: 07/31/2014] [Indexed: 10/24/2022]
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16
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Price OJ, Hull JH, Backer V, Hostrup M, Ansley L. The impact of exercise-induced bronchoconstriction on athletic performance: a systematic review. Sports Med 2015; 44:1749-61. [PMID: 25129699 DOI: 10.1007/s40279-014-0238-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Exercise-induced bronchoconstriction (EIB) describes the phenomenon of transient airway narrowing in association with physical activity. Although it may seem likely that EIB would have a detrimental impact on athletic performance, this has yet to be established. OBJECTIVES The aim of this review is to provide a systematic appraisal of the current status of knowledge regarding EIB and exercise performance and to highlight potential mechanisms by which performance may be compromised by EIB. DATA SOURCES AND STUDY SELECTION PubMed/Medline and EBSCO databases were searched up to May 2014 using the search parameter: [('exercise' OR 'athlete') AND ('asthma' OR 'bronchoconstriction' OR 'hypersensitivity') AND 'performance']. This search string returned 243 citations. After systematically reviewing all of the abstracts, 101 duplicate papers were removed, with 132 papers excluded for not including an exercise performance outcome measure. RESULTS The remaining ten studies that met the initial criteria were included in this review; six evaluated the performance of physically active individuals with asthma and/or EIB while four assessed the effects of medication on performance in a comparable population. CONCLUSION The evidence concludes that whilst it is reasonable to suspect that EIB does impact athletic performance, there is currently insufficient evidence to provide a definitive answer.
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Affiliation(s)
- Oliver J Price
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK,
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17
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Berntsen S, Lødrup Carlsen KC, Anderssen SA, Mowinckel P, Carlsen KH. Factors associated with aerobic fitness in adolescents with asthma. Respir Med 2013; 107:1164-71. [PMID: 23632101 DOI: 10.1016/j.rmed.2013.04.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 04/01/2013] [Accepted: 04/08/2013] [Indexed: 11/20/2022]
Abstract
BACKGROUND In adolescents with asthma, information on factors associated with cardiorespiratory fitness levels is limited. The present study aimed to determine if objectively measured physical activity as well as potential relevant factors such as lung function, asthma exacerbations, use of inhaled corticosteroids or skin fold thickness are associated with direct measurements of peak oxygen uptake (V˙O2peak) in adolescents with asthma. METHODS From a nested case-control study at 13-years in the Environment and Childhood Asthma birth cohort study in Oslo, Norway, 86 13-years old adolescents with and 76 without asthma performed maximal running on a treadmill with V˙O2peak measured. The sum of four skin fold thicknesses was recorded, followed by wearing an activity monitor for four consecutive days. Lung function was measured by maximum forced expiratory flow-volume curves and body plethysmography. Asthma exacerbations and use of medication were registered by parental structured interview. Data were analysed using multiple regression analysis. RESULTS Vigorous physical activity (coefficients with 95% confidence intervals; 1.73 (0.32, 3.14)) and skin fold thickness -0.35 (-0.41, -0.28)) were significantly associated with V˙O2peak in adolescents with asthma. Neither use of inhaled corticosteroids, lung function nor number of asthma exacerbations was associated with V˙O2peak when taking physical activity and skin fold thickness into account. In the adolescents without asthma only skin fold thicknesses was negatively associated with V˙O2peak -3.5 (-4.1, -2.8). CONCLUSIONS V˙O2peak appears to be determined by vigorous physical activity level in Norwegian adolescents with asthma and not by asthma-related factors such as use of inhaled corticosteroids, lung function nor number of asthma exacerbations.
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18
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Exercise-induced bronchoconstriction. Ann Allergy Asthma Immunol 2013; 110:311-5. [PMID: 23621999 DOI: 10.1016/j.anai.2013.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 01/11/2013] [Accepted: 02/04/2013] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To review the literature regarding the pathophysiology of exercise-induced bronchoconstriction (EIB). DATA SOURCES The databases of PubMed, Ovid MEDLINE, and Scopus were searched for articles using the subject headings and/or keywords asthma, exercise-induced/etiology, exercise, mechanism, pathogenesis, and bronchoconstriction. STUDY SELECTIONS Articles were selected based on their relevance to the focus of this review, with emphasis on the specific pathophysiologic mechanisms of EIB. RESULTS EIB occurs in response to the loss of water from the lower airways that results from heating and humidifying large volumes of air in a short period. The resulting hyperosmolar environment activates various cellular mechanisms to release mediators from mast cells, eosinophils, epithelial cells, and sensory nerves. These mediators, in turn, lead to airway smooth muscle contraction and bronchoconstriction. Airway hyperresponsiveness in elite athletes may develop from a process of airway injury and changes in the contractile properties of airway smooth muscle. CONCLUSION EIB commonly affects individuals with and without clinically recognized asthma, especially those who participate in competitive athletics. Through years of research, the pathophysiology of EIB is now better understood and involves a complex interaction between several different cell types and mediators. Continued research to improve the knowledge regarding the mechanisms of EIB should aid the identification, diagnosis, and treatment of this common condition.
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Dempsey JA, McKenzie DC, Haverkamp HC, Eldridge MW. Update in the Understanding of Respiratory Limitations to Exercise Performance in Fit, Active Adults. Chest 2008; 134:613-622. [DOI: 10.1378/chest.07-2730] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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20
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Muñoz PA, Gómez FP, Manrique HA, Roca J, Barberà JA, Young IH, Anderson SD, Rodríguez-Roisin R. Pulmonary gas exchange response to exercise- and mannitol-induced bronchoconstriction in mild asthma. J Appl Physiol (1985) 2008; 105:1477-85. [PMID: 18756011 DOI: 10.1152/japplphysiol.00108.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Both exercise (EIB) and mannitol challenges were performed in asthmatic patients to assess and compare their pulmonary gas exchange responses for an equivalent degree of bronchoconstriction. In 11 subjects with EIB [27 +/- 4 (SD) yr; forced expiratory volume in 1 s (FEV(1)), 86 +/- 8% predicted], ventilation-perfusion (Va/Q) distributions (using multiple inert gas elimination technique) were measured 5, 15, and 45 min after cycling exercise (FEV(1) fall, 35 +/- 12%) and after mannitol (33 +/- 10%), 1 wk apart. Five minutes after EIB, minute ventilation (Ve; by 123 +/- 60%), cardiac output (Qt, by 48 +/- 29%), and oxygen uptake (Vo2; by 54 +/- 25%) increased, whereas arterial Po2 (Pa(O2); by 14 +/- 11 Torr) decreased due to moderate Va/Q imbalance, assessed by increases in dispersions of pulmonary blood flow (log SD(Q); by 0.53 +/- 0.16) and alveolar ventilation (log SD(V); by 0.28 +/- 0.15) (dimensionless) (P < 0.01 each). In contrast, for an equivalent degree of bronchoconstriction and minor increases in Ve, Qt, and Vo2, mannitol decreased Pa(O2) more intensely (by 24 +/- 9 Torr) despite fewer disturbances in log SDQ (by 0.27 +/- 0.12). Notwithstanding, mannitol-induced increase in log SDV at 5 min (by 0.35 +/- 0.15) was similar to that observed during EIB, as was the slow recovery in log SD(V) and high Va/Q ratio areas, at variance with the faster recovery of log SD(Q) and low Va/Q ratio areas. In asthmatic individuals, EIB provokes more Va/Q imbalance but less hypoxemia than mannitol, primarily due to postexercise increases in Ve and Qt benefiting Pa(O2). Va/Q inequalities during both challenges most likely reflect uneven airway narrowing and blood flow redistribution generating distinctive Va/Q patterns, including the development of areas with low and high Va/Q ratios.
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Affiliation(s)
- Phillip A Muñoz
- Servei de Pneumologia, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Ciber Enfermedades Respiratorias, Universitat de Barcelona, Spain
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21
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McKenzie DC, Boulet LP. Asthma, outdoor air quality and the Olympic Games. CMAJ 2008; 179:543-8. [PMID: 18687919 DOI: 10.1503/cmaj.080982] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- Donald C McKenzie
- Division of Sports Medicine and School of Human Kinetics, University of British Columbia, Vancouver, BC.
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Haverkamp HC, Dempsey JA, Pegelow DF, Miller JD, Romer LM, Santana M, Eldridge MW. Treatment of airway inflammation improves exercise pulmonary gas exchange and performance in asthmatic subjects. J Allergy Clin Immunol 2007; 120:39-47. [PMID: 17451800 DOI: 10.1016/j.jaci.2007.03.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 02/16/2007] [Accepted: 03/08/2007] [Indexed: 11/27/2022]
Abstract
BACKGROUND Asthma is an inflammatory disease of the airways that can lead to impaired arterial blood oxygenation during exercise. OBJECTIVE We asked whether treatment of airway inflammation in asthmatic subjects would improve arterial blood gases during whole-body exercise. METHODS By using a double-blind parallel-group design, 19 asthmatic subjects completed treadmill exercise to exhaustion on 2 occasions: (1) before and (2) after 6 weeks' treatment with an inhaled corticosteroid (ICS; n = 9) or placebo (n = 10). RESULTS The ICS group had improved resting pulmonary function, decreased exercise-induced bronchospasm, and decreased postexercise sputum histamine during the posttreatment study compared with that during the pretreatment study. In the ICS group exercise Pao(2) was significantly increased after treatment (84.8 to 93.8 mm Hg). Increased alveolar ventilation (arterial Pco(2) decreased from 36.9 to 34.1 mm Hg) accounted for 37% of the increased Pao(2) and improved gas exchange efficiency (alveolar-to-arterial Po(2) difference decreased from 22.5 to 16.3 mm Hg) accounted for the remaining 63% of the increased Pao(2) after treatment. In the ICS group exercise time to exhaustion was increased from 9.9 minutes during the pretreatment study to 14.8 minutes during the posttreatment study. CONCLUSION Treatment of airway inflammation in asthmatic subjects can improve arterial blood oxygenation during exercise by (1) improving airway function, thereby allowing increased alveolar ventilation during exercise, and (2) improving the efficiency of alveolar-to-arterial blood O(2) exchange. CLINICAL IMPLICATIONS In asthmatic patients ICSs not only attenuate exercise-induced bronchospasm but also improve arterial blood oxygenation during exercise.
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Affiliation(s)
- Hans C Haverkamp
- Department of Medicine, University of Vermont, Vermont Lung Center, Burlington, VT 05405, USA.
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Haverkamp HC, Dempsey JA, Miller JD, Romer LM, Pegelow DF, Lovering AT, Eldridge MW. Repeat exercise normalizes the gas-exchange impairment induced by a previous exercise bout in asthmatic subjects. J Appl Physiol (1985) 2005; 99:1843-52. [PMID: 16037395 DOI: 10.1152/japplphysiol.01399.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Twenty-one subjects with asthma underwent treadmill exercise to exhaustion at a workload that elicited approximately 90% of each subject's maximal O2 uptake (EX1). After EX1, 12 subjects experienced significant exercise-induced bronchospasm [(EIB+), %decrease in forced expiratory volume in 1.0 s = -24.0 +/- 11.5%; pulmonary resistance at rest vs. postexercise = 3.2 +/- 1.5 vs. 8.1 +/- 4.5 cmH2O.l(-1).s(-1)] and nine did not (EIB-). The alveolar-to-arterial Po2 difference (A-aDo2) was widened from rest (9.1 +/- 6.7 Torr) to 23.1 +/- 10.4 and 18.1 +/- 9.1 Torr at 35 min after EX1 in subjects with and without EIB, respectively (P < 0.05). Arterial Po2 (PaO2) was reduced in both groups during recovery (EIB+, -16.0 +/- -13.0 Torr vs. baseline; EIB-, -11.0 +/- 9.4 Torr vs. baseline, P < or = 0.05). Forty minutes after EX1, a second exercise bout was completed at maximal O2 uptake. During the second exercise bout, pulmonary resistance decreased to baseline levels in the EIB+ group and the A-aDo2 and PaO2 returned to match the values seen during EX1 in both groups. Sputum histamine (34.6 +/- 25.9 vs. 61.2 +/- 42.0 ng/ml, pre- vs. postexercise) and urinary 9alpha,11beta-prostaglandin F2 (74.5 +/- 38.6 vs. 164.6 +/- 84.2 ng/mmol creatinine, pre- vs. postexercise) were increased after exercise only in the EIB+ group (P < 0.05), and postexercise sputum histamine was significantly correlated with the exercise PaO2 and A-aDo2 in the EIB+ subjects. Thus exercise causes gas-exchange impairment during the postexercise period in asthmatic subjects independent of decreases in forced expiratory flow rates after the exercise; however, a subsequent exercise bout normalizes this impairment secondary in part to a fast acting, robust exercise-induced bronchodilatory response.
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Affiliation(s)
- H C Haverkamp
- Department of Population Health Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA.
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