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Baur DA, Baur KG, Buchanan BK, Ortiz MJ, Doody AG. Load carriage physiology in normoxia and hypoxia. Eur J Appl Physiol 2024; 124:925-943. [PMID: 37740748 PMCID: PMC10879375 DOI: 10.1007/s00421-023-05320-2] [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: 06/06/2023] [Accepted: 09/08/2023] [Indexed: 09/25/2023]
Abstract
PURPOSE To determine the effects of load carriage in normoxia and normobaric hypoxia on ventilatory responses, hemodynamics, tissue oxygenation, and metabolism. METHODS Healthy males (n = 12) completed 3 randomly ordered baseline graded exercise tests in the following conditions: (1) unloaded normoxic (U: FIO2 = 20.93%), (2) loaded (~ 30 kg) normoxic (LN), and (3) loaded hypoxic simulating ~ 3650 m (LH: FIO2 = ~ 13%). Thereafter, experimental exercise trials were completed in quasi-randomized order (i.e., U completed first) consisting of 3 × 10 min of walking (separated by 5 min seated rest) with stages matched with the U condition (in ascending order) for relative intensity, absolute oxygen consumption ([VO2]; 1.7 L min-1), and walking speed (1.45 ± 0.15 m s-1). RESULTS Load carriage increased perceived exertion and reduced VO2max (LN: - 7%; LH: - 32%; p < 0.05). At matched VO2, stroke volume and tidal volume were reduced and maintained with LN and LH vs. U, respectively (p < 0.05). Increases in cardiac output and minute ventilation at matched VO2 (with LH) and speed (with LN and LH), were primarily accomplished via increases in heart rate and breathing frequency (p < 0.05). Cerebral oxygenated hemoglobin (O2HHb) was increased at all intensities with LN, but deoxygenated hemoglobin and total hemoglobin were increased with LH (p < 0.05). Muscle oxygen kinetics and substrate utilization were similar between LN and U, but LH increased CHO dependence and reduced muscle O2HHb at matched speed (p < 0.05). CONCLUSION Load carriage reduces cardiorespiratory efficiency and increases physiological strain, particularly in hypoxic environments. Potential load carriage-induced alterations in cerebral blood flow may increase the risk for altitude illnesses and requires further study.
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Affiliation(s)
- Daniel A Baur
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA.
| | - Katherine G Baur
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Beverley K Buchanan
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Miles J Ortiz
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Abaigeal G Doody
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
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2
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Smith JR, Senefeld JW, Larson KF, Joyner MJ. Consequences of group III/IV afferent feedback and respiratory muscle work on exercise tolerance in heart failure with reduced ejection fraction. Exp Physiol 2023; 108:1351-1365. [PMID: 37735814 PMCID: PMC10900130 DOI: 10.1113/ep090755] [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: 12/29/2022] [Accepted: 09/06/2023] [Indexed: 09/23/2023]
Abstract
Exercise intolerance and exertional dyspnoea are the cardinal symptoms of heart failure with reduced ejection fraction (HFrEF). In HFrEF, abnormal autonomic and cardiopulmonary responses arising from locomotor muscle group III/IV afferent feedback is one of the primary mechanisms contributing to exercise intolerance. HFrEF patients also have pulmonary system and respiratory muscle abnormalities that impair exercise tolerance. Thus, the primary impetus for this review was to describe the mechanistic consequences of locomotor muscle group III/IV afferent feedback and respiratory muscle work in HFrEF. To address this, we first discuss the abnormal autonomic and cardiopulmonary responses mediated by locomotor muscle afferent feedback in HFrEF. Next, we outline how respiratory muscle work impairs exercise tolerance in HFrEF through its effects on locomotor muscle O2 delivery. We then discuss the direct and indirect evidence supporting an interaction between locomotor muscle group III/IV afferent feedback and respiratory muscle work during exercise in HFrEF. Last, we outline future research directions related to locomotor and respiratory muscle abnormalities to progress the field forward in understanding the pathophysiology of exercise intolerance in HFrEF. NEW FINDINGS: What is the topic of this review? This review is focused on understanding the role that locomotor muscle group III/IV afferent feedback and respiratory muscle work play in the pathophysiology of exercise intolerance in patients with heart failure. What advances does it highlight? This review proposes that the concomitant effects of locomotor muscle afferent feedback and respiratory muscle work worsen exercise tolerance and exacerbate exertional dyspnoea in patients with heart failure.
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Affiliation(s)
- Joshua R. Smith
- Department of Cardiovascular MedicineMayo ClinicRochesterMNUSA
| | - Jonathon W. Senefeld
- Department of Anesthesiology and Perioperative MedicineMayo ClinicRochesterMNUSA
- Department of Kinesiology and Community HealthUniversity of Illinois at Urbana‐ChampaignUrbanaILUSA
| | | | - Michael J. Joyner
- Department of Anesthesiology and Perioperative MedicineMayo ClinicRochesterMNUSA
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3
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Vasquez-Bonilla AA, Brazo-Sayavera J, Timón R, Olcina G. Monitoring Muscle Oxygen Asymmetry as a Strategy to Prevent Injuries in Footballers. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2023; 94:609-617. [PMID: 35442862 DOI: 10.1080/02701367.2022.2026865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 12/30/2021] [Indexed: 06/14/2023]
Abstract
Purpose: It has been hypothesized that sports injury risk is explained by muscle metabolism. The objective was to evaluate the muscle oxygen saturation slopes (ΔSmO2 slopes) and muscle oxygenation asymmetry (MO2Asy) at rest and to study their associations with injuries during the pre-season. Methods: A total of 16 male and 10 female footballers participated in this study. Injuries were diagnosed and classified by level of severity during the pre-season. The workload was also evaluated using the rate of perceived exertion × training time, from which the accumulated loads. The SmO2 was measured at rest in the gastrocnemius muscle using the arterial occlusion method in the dominant and non-dominant legs. The repeated measures ANOVA, relative risk, and binary logistic regression were applied to assess the probability of injury with SmO2 and workload. Results: Higher MO2Asy and ΔSmO2 Slope 2 were found among footballer who suffered high-severity injuries and those who presented no injuries. In addition, an MO2Asy greater than 15% and an increase in accumulated load were variables that explained a greater probability of injury. Conclusion: This study presents the new concept of muscle oxygenation asymmetry in sports science and its possible application in injury prevention through the measurement of SmO2 at rest.
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Schaer CE, Erne D, Tageldin D, Wüthrich TU, Beltrami FG, Spengler CM. Effects of Sprint Interval and Endurance Respiratory Muscle Training on Postcycling Inspiratory and Quadriceps Fatigue. Med Sci Sports Exerc 2023; 55:1683-1694. [PMID: 37076980 DOI: 10.1249/mss.0000000000003192] [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: 04/21/2023]
Abstract
PURPOSE We investigated whether a 4-wk period of respiratory muscle endurance training (RMET) or respiratory muscle sprint interval training (RMSIT) would lead to an attenuation of inspiratory muscle and quadriceps fatigue after a bout of high-intensity cycling compared with a placebo intervention (PLAT), as predicted by the respiratory metaboreflex model. METHODS Thirty-three active, young healthy adults performed RMET, RMSIT, or PLAT. Changes in inspiratory muscle and quadriceps twitches in response to a cycling test at 90% of peak work capacity were assessed before and after training. EMG activity and deoxyhemoglobin (HHb, via near-infrared spectroscopy) of the quadriceps and inspiratory muscles were also monitored during the cycling test, along with cardiorespiratory and perceptual variables. RESULTS At pretraining, cycling reduced the twitch force of the inspiratory muscles (86% ± 11% baseline) and quadriceps (66% ± 16% baseline). Training did not attenuate the drop in twitch force of the inspiratory muscles (PLAT, -3.5 ± 4.9 percent-points [p.p.]; RMET, 2.7 ± 11.3 p.p.; RMSIT, 4.1 ± 8.5 p.p.; group-training interaction, P = 0.394) or quadriceps (PLAT, 3.8 ± 18.6 p.p.; RMET, -2.6 ± 14.0 p.p.; RMSIT, 5.2 ± 9.8 p.p.; group-training interaction P = 0.432). EMG activity and HHb levels during cycling did not change after training for either group. Only RMSIT showed a within-group decrease in the perception of respiratory exertion with training. CONCLUSIONS Four weeks of RMET or RMSIT did not attenuate the development of exercise-induced inspiratory or quadriceps fatigue. The ergogenic effects of respiratory muscle training during whole-body exercise might be related to an attenuation of perceptual responses.
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Affiliation(s)
- Corina E Schaer
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, SWITZERLAND
| | - Desirée Erne
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, SWITZERLAND
| | - Dina Tageldin
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, SWITZERLAND
| | - Thomas U Wüthrich
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, SWITZERLAND
| | - Fernando G Beltrami
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, SWITZERLAND
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5
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Leahy MG, Kipp S, Benbaruj JM, Charkoudian N, Foster GE, Koehle MS, Sheel AW. Effects of sex and ageing on the human respiratory muscle metaboreflex. J Physiol 2023; 601:689-702. [PMID: 36453597 DOI: 10.1113/jp283838] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 11/22/2022] [Indexed: 12/05/2022] Open
Abstract
Intense inspiratory muscle work evokes a sympathetically mediated pressor reflex, termed the respiratory muscle metaboreflex, in which young females demonstrate an attenuated response relative to males. However, the effects of ageing and female sex hormones on the respiratory muscle metaboreflex are unclear. We tested the hypothesis that the pressor response to inspiratory work would be similar between older males and females, and higher relative to their younger counterparts. Healthy, normotensive young (26 ± 3 years) males (YM; n = 10) and females (YF; n = 10), as well as older (64 ± 5 years) males (OM; n = 10) and females (OF; n = 10), performed inspiratory pressure threshold loading (PTL) to task failure. Older adults had a greater mean arterial pressure (MAP) response to PTL than young (P < 0.001). YF had a lower MAP compared to YM (+10 ± 6 vs. +19 ± 15 mmHg, P = 0.026); however, there was no difference observed between OF and OM (+26 ± 11 vs. +27 ± 11 mmHg, P = 0.162). Older adults had a lower heart rate response to PTL than young (P = 0.002). There was no effect of sex between young females and males (+19 ± 9 and +27 ± 11 bpm, P = 0.186) or older females and males (+17 ± 7 and +20 ± 7 bpm, P = 0.753). We conclude the respiratory muscle metaboreflex response is heightened in older adults, and the sex effect between older males and post-menopause females is absent, suggesting an effect of circulating sex hormones. KEY POINTS: The arterial blood pressure response to the respiratory muscle metaboreflex is greater in older males and females. Compared to sex-matched young individuals, there is no sex differences in the blood pressure response between older males and post-menopause females. Our results suggest the differences between males and females in the cardiovascular response to high levels of inspiratory muscle work is abolished with reduced circulating female sex hormones.
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Affiliation(s)
- Michael G Leahy
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Shalaya Kipp
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Jenna M Benbaruj
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Nisha Charkoudian
- Thermal & Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, BC, Canada
| | - Michael S Koehle
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Divison of Sport Medicine, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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6
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Hammer SM, Bruhn EJ, Bissen TG, Muer JD, Villarraga N, Borlaug BA, Olson TP, Smith JR. Inspiratory and leg muscle blood flows during inspiratory muscle metaboreflex activation in heart failure with preserved ejection fraction. J Appl Physiol (1985) 2022; 133:1202-1211. [PMID: 36227167 PMCID: PMC9639766 DOI: 10.1152/japplphysiol.00141.2022] [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: 03/07/2022] [Revised: 09/29/2022] [Accepted: 10/07/2022] [Indexed: 11/22/2022] Open
Abstract
The purpose of this study was to determine the cardiovascular consequences elicited by activation of the inspiratory muscle metaboreflex in patients with heart failure with preserved ejection fraction (HFpEF) and controls. Patients with HFpEF (n = 15; 69 ± 10 yr; 33 ± 4 kg/m2) and controls (n = 14; 70 ± 8 yr; 28 ± 4 kg/m2) performed an inspiratory loading trial at 60% maximal inspiratory pressure (PIMAX) until task failure. Mean arterial pressure (MAP) was measured continuously. Near-infrared spectroscopy and bolus injections of indocyanine green dye were used to determine the percent change in blood flow index (%ΔBFI) from baseline to the final minute of inspiratory loading in the vastus lateralis and sternocleidomastoid muscles. Vascular resistance index (VRI) was calculated. Time to task failure was shorter in HFpEF than in controls (339 ± 197 s vs. 626 ± 403 s; P = 0.02). Compared with controls, patients with HFpEF had a greater increase from baseline in MAP (16 ± 7 vs. 10 ± 6 mmHg) and vastus lateralis VRI (76 ± 45 vs. 32 ± 19%) as well as a greater decrease in vastus lateralis %ΔBFI (-32 ± 14 vs. -17 ± 9%) (all, P < 0.05). Sternocleidomastoid %ΔBFI normalized to absolute inspiratory pressure was higher in HFpEF compared with controls (8.0 ± 5.0 vs. 4.0 ± 1.9% per cmH2O·s; P = 0.03). These data indicate that patients with HFpEF exhibit exaggerated cardiovascular responses with inspiratory muscle metaboreflex activation compared with controls.NEW & NOTEWORTHY Respiratory muscle dysfunction is thought to contribute to exercise intolerance in heart failure with preserved ejection fraction (HFpEF); however, the underlying mechanisms are unknown. In the present study, patients with HFpEF had greater increases in leg muscle vascular resistance index and greater decreases in leg muscle blood flow index compared with controls during inspiratory resistive breathing (to activate the metaboreflex). Furthermore, respiratory muscle blood flow index responses normalized to pressure generation during inspiratory resistive breathing were exaggerated in HFpEF compared with controls.
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Affiliation(s)
- Shane M Hammer
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, Oklahoma
| | - Eric J Bruhn
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
| | - Thomas G Bissen
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
| | - Jessica D Muer
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
| | - Nicolas Villarraga
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
| | - Barry A Borlaug
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
| | - Thomas P Olson
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
| | - Joshua R Smith
- Department of Cardiovascular Medicine, https://ror.org/03zzw1w08Mayo Clinic, Rochester, Minnesota
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7
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Shiozawa K, Kashima H, Mizuno S, Ishida K, Katayama K. Blood pressure and celiac artery blood flow responses during increased inspiratory muscle work in healthy males. Exp Physiol 2022; 107:1094-1104. [PMID: 35770992 DOI: 10.1113/ep090504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 06/23/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Increased work of breathing and the accumulation of metabolites have neural and cardiovascular consequences through a respiratory muscle-induced metaboreflex. The influence of respiratory muscle-induced metaboreflex on splanchnic blood flow in humans remains unknown. What is the main finding and its importance? Celiac artery blood flow decreased gradually during inspiratory resistive breathing, accompanied by a progressive increase in arterial blood pressure. It is possible that respiratory muscle-induced metaboreflex contributes to splanchnic blood flow regulation. ABSTRACT The purpose of this study was to clarify the effect of increasing inspiratory muscle work on celiac artery blood flow. Eleven healthy young males completed the study. The subjects performed voluntary hyperventilation with or without inspiratory resistance (loading or non-loading trial) (tidal volume of 40% of vital capacity and breathing frequency of 20 breaths/min). The loading trial was conducted with inspiratory resistance (40% of maximal inspiratory pressure) and was terminated when the subjects could no longer maintain the target tidal volume or breathing frequency. The non-loading trial was conducted without inspiratory resistance and was the same length as the loading trial. Arterial blood pressure was recorded using finger photoplethysmography, and celiac artery blood flow was measured using Doppler ultrasound. Mean arterial blood pressure (MAP) increased gradually during the loading trial (89.0±10.8 to 103.9±17.3 mmHg, mean ± SD) but not in the non-loading trial (88.7±5.9 to 90.4±9.9 mmHg). Celiac artery blood flow and celiac vascular conductance decreased gradually during the loading trial (601.2±155.7 to 482.6±149.5 mL/min and 6.9±2.2 to 4.8±1.7 mL/min/mmHg, respectively), but were unchanged in the non-loading trial (630.7±157.1 to 635.6±195.7 mL/min and 7.1±1.8 to 7.2±2.9 mL/min/mmHg, respectively). These results show that increasing inspiratory muscle work affects splanchnic blood flow regulation, and we suggest that it is possibly mediated by the inspiratory muscle-induced metaboreflex. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kana Shiozawa
- Graduate School of Medicine, Nagoya University, Nagoya, Japan
| | - Hideaki Kashima
- Department of Health Sciences, Prefectural University of Hiroshima, Japan
| | - Sahiro Mizuno
- Research and Development, Hosei University, Tokyo, Japan
| | - Koji Ishida
- Graduate School of Medicine, Nagoya University, Nagoya, Japan.,Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
| | - Keisho Katayama
- Graduate School of Medicine, Nagoya University, Nagoya, Japan.,Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
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8
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Respiratory muscle training improves exercise tolerance and respiratory muscle function/structure post-stroke at short term: A systematic review and meta-analysis. Ann Phys Rehabil Med 2021; 65:101596. [PMID: 34687960 DOI: 10.1016/j.rehab.2021.101596] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 07/21/2021] [Accepted: 07/31/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Previous reviews relating to the effects of respiratory muscle training (RMT) after stroke tend to focus on only one type of training (inspiratory or expiratory muscles) and most based the results on poor-quality studies (PEDro score ≤4). OBJECTIVES With this systematic review and meta-analysis, we aimed to determine the effects of RMT (inspiratory or expiratory muscle training, or mixed) on exercise tolerance, respiratory muscle function and pulmonary function and also the effects depending on the type of training performed at short- and medium-term in post-stroke. METHODS Databases searched were MEDLINE, PEDro, CINAHL, EMBASE and Web of Science up to the end of April 2020. The quality and risk of bias for each included study was examined by the PEDro scale (including only high-quality studies) and Cochrane Risk of Bias tool. RESULTS Nine studies (463 patients) were included. The meta-analysis showed a significant increase in exercise tolerance [4 studies; n = 111; standardized mean difference [SMD] = 0.65 (95% confidence interval 0.27-1.04)]; inspiratory muscle strength [9 studies; n = 344; SMD = 0.65 (0.17-1.13)]; inspiratory muscle endurance [3 studies; n = 81; SMD = 1.19 (0.71-1.66)]; diaphragm thickness [3 studies; n = 79; SMD = 0.9 (0.43-1.37)]; and peak expiratory flow [3 studies; n = 84; SMD = 0.55 (0.03-1.08)] in the short-term. There were no benefits on expiratory muscle strength and pulmonary function variables (forced expiratory volume in 1 s) in the short-term. CONCLUSIONS The meta-analysis provided moderate-quality evidence that RMT improves exercise tolerance, diaphragm thickness and pulmonary function (i.e., peak expiratory flow) and low-quality evidence for the effects on inspiratory muscle strength and endurance in stroke survivors in the short-term. None of these effects are retained in the medium-term. Combined inspiratory and expiratory muscle training seems to promote greater respiratory changes than inspiratory muscle training alone.
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9
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Sheel AW, Taylor JL, Katayama K. The hyperpnoea of exercise in health: Respiratory influences on neurovascular control. Exp Physiol 2020; 105:1984-1989. [PMID: 32034952 DOI: 10.1113/ep088103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 02/03/2020] [Indexed: 12/29/2022]
Abstract
NEW FINDINGS What is the topic of this review? Elevated demand is placed on the respiratory muscles during whole-body exercise-induced hyperpnoea. What is the role of elevated demand in neural modulation of cardiovascular control in respiratory and locomotor skeletal muscle, and what are the mechanisms involved? What advances does it highlight? There is a sympathetic restraint of blood flow to locomotor muscles during near-maximal exercise, which might function to maintain blood pressure. During submaximal exercise, respiratory muscle blood flow might be also be reduced if ventilatory load is sufficiently high. Methodological advances (near-infrared spectroscopy with indocyanine green) confirm that blood flow is diverted away from respiratory muscles when the work of breathing is alleviated. ABSTRACT It is known that the respiratory muscles have a significant increasing oxygen demand in line with hyperpnoea during whole-body endurance exercise and are susceptible to fatigue, in much the same way as locomotor muscles. The act of ventilation can itself be considered a form of exercise. The manipulation of respiratory load at near-maximal exercise alters leg blood flow significantly, demonstrating a competitive relationship between different skeletal muscle vascular beds to perfuse both sets of muscles adequately with a finite cardiac output. In recent years, the question has moved towards whether this effect exists during submaximal exercise, and the use of more direct measurements of respiratory muscle blood flow itself to confirm assumptions that uphold the concept. Evidence thus far has shown that there is a reciprocal effect on blood flow redistribution during ventilatory load manipulation observed at the respiratory muscles themselves and that the effect is observable during submaximal exercise, where active limb blood flow was reduced in conditions that simulated a high work of breathing. This has clinical applications for populations with respiratory disease and heart failure, where the work of breathing is remarkably high, even during submaximal efforts.
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Affiliation(s)
- A William Sheel
- School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC, Canada
| | - Joshua Landen Taylor
- School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC, Canada
| | - Keisho Katayama
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan.,Graduate School of Medicine, Nagoya University, Nagoya, Japan
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10
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Cross TJ, Kim CH, Johnson BD, Lalande S. The interactions between respiratory and cardiovascular systems in systolic heart failure. J Appl Physiol (1985) 2019; 128:214-224. [PMID: 31774354 DOI: 10.1152/japplphysiol.00113.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heart failure (HF) is a complex and multifaceted disease. The disease affects multiple organ systems, including the respiratory system. This review provides three unique examples illustrating how the cardiovascular and respiratory systems interrelate because of the pathology of HF. Specifically, these examples outline the impact of HF pathophysiology on 1) respiratory mechanics and the mechanical "cost" of breathing; 2) mechanical interactions of the heart and lungs; and on 3) abnormalities of pulmonary gas exchange during exercise, and how this may be applied to treatment. The goal of this review is to, therefore, raise the awareness that HF, though primarily a disease of the heart, is accompanied by marked pathology of the respiratory system.
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Affiliation(s)
- Troy James Cross
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester Minnesota
| | - Chul-Ho Kim
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester Minnesota
| | - Bruce D Johnson
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester Minnesota
| | - Sophie Lalande
- Department of Kinesiology and Heath Education, University of Texas at Austin, Austin, Texas
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11
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Geary CM, Welch JF, McDonald MR, Peters CM, Leahy MG, Reinhard PA, Sheel AW. Diaphragm fatigue and inspiratory muscle metaboreflex in men and women matched for absolute diaphragmatic work during pressure-threshold loading. J Physiol 2019; 597:4797-4808. [PMID: 31348520 DOI: 10.1113/jp278380] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/23/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The female diaphragm fatigues at a slower rate compared to that of males, with blunted cardiovascular consequences (i.e. inspiratory muscle metaboreflex). It is unclear if these findings are a function of relative or absolute diaphragmatic work. We asked if sex differences in diaphragm fatigue and the inspiratory muscle metaboreflex persisted during inspiratory loading performed at equal absolute intensities. We found that matching men and women for absolute diaphragmatic work resulted in an equal degree of diaphragm fatigue, despite women performing significantly greater work relative to body mass. Metabolite-induced reflex influences in sympathetic outflow originating from the diaphragm are attenuated in women, with potential implications for blood flow distribution during exercise. ABSTRACT In response to inspiratory pressure-threshold loading (PTL), women have greater inspiratory muscle endurance time, slower rate of diaphragm fatigue development, and a blunted pressor response compared to men. It is unclear if these differences are due to discrepancies in absolute diaphragm force output. We tested the hypothesis that following inspirations performed at equal absolute intensities, females would develop a similar level of diaphragm fatigue and an attenuated cardiovascular response relative to men. Healthy young men (n = 8, age = 24 ± 3 years) and women (n = 8, age = 23 ± 3 years) performed PTL whilst targeting a transdiaphragmatic pressure (Pdi ) of 92 cmH2 O for 5 min. Diaphragm fatigue was assessed via twitch Pdi (Pdi,tw ) using cervical magnetic stimulation. Heart rate (HR) and mean arterial blood pressure were monitored continuously. During PTL, the absolute amount of diaphragm work was not different between men (13,399 ± 2019 cmH2 O s) and women (12,986 ± 1846 cmH2 O s; P > 0.05); however, women performed the PTL task at a higher relative P ¯ di /Pdi,max . Following inspiratory PTL, the magnitude of reduction in Pdi,tw was similar between men (-27.1 ± 7.2%) and women (-23.8 ± 13.8%; P > 0.05). There were significant increases in HR over time (P < 0.05), but this did not differ on the basis of sex (P > 0.05). Mean arterial blood pressure increased significantly over time in both men and women (P < 0.05); however, the rate of change was higher in men (6.24 ± 2.54 mmHg min-1 ) than in women (4.15 ± 2.52 mmHg min-1 ) (P < 0.05). We conclude that the female diaphragm is protected against severe fatigue when inspiratory work is excessive and as a result does not evoke overt sympathoexcitation.
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Affiliation(s)
- Caitlin M Geary
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Joseph F Welch
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Malcolm R McDonald
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Carli M Peters
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Michael G Leahy
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Paige A Reinhard
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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12
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Phillips DB, Stickland MK. Respiratory limitations to exercise in health: a brief review. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Hoffmeister AD, Lima KSD, Cavalli NP, Callegaro CC. Metaborreflexo inspiratório eleva a pressão arterial em indivíduos obesos e eutróficos. FISIOTERAPIA EM MOVIMENTO 2019. [DOI: 10.1590/1980-5918.0032.ao42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Resumo Introdução: O metaborreflexo, ativado pelo acúmulo de metabólitos durante o exercício, ocasiona vasoconstrição periférica, resultando em elevação da pressão arterial. Indivíduos obesos apresentam redução da endurance muscular inspiratória, sugerindo um acúmulo precoce de metabólitos e, consequentemente, alterações no metaborreflexo inspiratório. Objetivo: Comparar as respostas hemodinâmicas mediadas pelo metaborreflexo inspiratório em indivíduos obesos e em eutróficos. Método: Participaram do estudo vinte indivíduos obesos (31 ± 6 anos, dez homens, 37,5 ± 4,7 kg/m 2 ) e vinte eutróficos (29 ± 8 anos, dez homens, 23,2 ± 1,5 kg/m 2 ) submetidos a avaliação da força muscular respiratória através de manovacuometria. O metaborreflexo inspiratório foi induzido através de exercício resistido a 60% da pressão inspiratória máxima mantido até a exaustão. O protocolo controle consistiu na respiração sem resistência inspiratória (zero cmH 2 O) mantida durante 30 minutos. A pressão arterial e a frequência cardíaca foram mensuradas ao longo dos protocolos, realizados em dias distintos e em ordem randomizada. Resultados: O protocolo de indução do metaborreflexo inspiratório induziu aumento das pressões arteriais sistólica, diastólica e média, bem como da frequência cardíaca semelhante em indivíduos obesos e eutróficos. Conforme esperado, no protocolo controle as variáveis hemodinâmicas permaneceram inalteradas. Conclusão: A força muscular inspiratória não variou (p = 0,814) entre indivíduos obesos e eutróficos. Este estudo sugere que indivíduos obesos apresentam respostas hemodinâmicas, induzidas pelo metaborreflexo inspiratório, semelhantes aos indivíduos eutróficos.
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Hoffmeister AD, Lima KSD, Albuquerque IMD, Binotto V, Callegaro CC. Endurance muscular inspiratória em indivíduos obesos e eutróficos. FISIOTERAPIA E PESQUISA 2018. [DOI: 10.1590/1809-2950/18005525042018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
RESUMO O objetivo deste estudo foi comparar a endurance muscular inspiratória e as respostas hemodinâmicas de indivíduos obesos e eutróficos. Trata-se de um estudo transversal com amostra composta por 20 indivíduos obesos (31±6 anos, 10 homens, 37,5±4,7 kg/m2) e 20 indivíduos eutróficos (29±8 anos, 10 homens, 23,2±1,5 kg/m2). A força muscular inspiratória e expiratória foi mensurada por manovacuometria, através da determinação da pressão inspiratória máxima e da pressão expiratória máxima. A endurance muscular inspiratória foi determinada por meio de exercício inspiratório com carga progressiva, iniciado com carga de 50% da pressão inspiratória máxima por 3 minutos, seguidos de incremento de 10% a cada 3 minutos até que o indivíduo fosse incapaz de continuar o teste. Verificou-se que os indivíduos obesos (470 ± 326 seg) apresentaram endurance muscular inspiratória reduzida em comparação com os eutróficos (651 ± 215 seg). A força muscular inspiratória e expiratória não diferiu entre os grupos. O teste de exercício progressivo induziu aumento da pressão arterial sistólica, diastólica e média e da frequência cardíaca, semelhante em indivíduos obesos e eutróficos. Foi possível concluir que embora a endurance muscular inspiratória de indivíduos obesos seja menor que a de eutróficos, as respostas hemodinâmicas induzidas pelo teste de endurance muscular inspiratória foram semelhantes nos dois grupos.
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15
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Sheel AW, Boushel R, Dempsey JA. Competition for blood flow distribution between respiratory and locomotor muscles: implications for muscle fatigue. J Appl Physiol (1985) 2018; 125:820-831. [PMID: 29878876 DOI: 10.1152/japplphysiol.00189.2018] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Sympathetically induced vasoconstrictor modulation of local vasodilation occurs in contracting skeletal muscle during exercise to ensure appropriate perfusion of a large active muscle mass and to maintain also arterial blood pressure. In this synthesis, we discuss the contribution of group III-IV muscle afferents to the sympathetic modulation of blood flow distribution to locomotor and respiratory muscles during exercise. This is followed by an examination of the conditions under which diaphragm and locomotor muscle fatigue occur. Emphasis is given to those studies in humans and animal models that experimentally changed respiratory muscle work to evaluate blood flow redistribution and its effects on locomotor muscle fatigue, and conversely, those that evaluated the influence of coincident limb muscle contraction on respiratory muscle blood flow and fatigue. We propose the concept of a "two-way street of sympathetic vasoconstrictor activity" emanating from both limb and respiratory muscle metaboreceptors during exercise, which constrains blood flow and O2 transport thereby promoting fatigue of both sets of muscles. We end with considerations of a hierarchy of blood flow distribution during exercise between respiratory versus locomotor musculatures and the clinical implications of muscle afferent feedback influences on muscle perfusion, fatigue, and exercise tolerance.
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Affiliation(s)
- A William Sheel
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Robert Boushel
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Jerome A Dempsey
- Department of Population Health Sciences, John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin , Madison, Wisconsin
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16
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Horiuchi M, Endo J, Dobashi S, Handa Y, Kiuchi M, Koyama K. Muscle oxygenation profiles between active and inactive muscles with nitrate supplementation under hypoxic exercise. Physiol Rep 2018; 5:5/20/e13475. [PMID: 29066597 PMCID: PMC5661236 DOI: 10.14814/phy2.13475] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 12/02/2022] Open
Abstract
Whether dietary nitrate supplementation improves exercise performance or not is still controversial. While redistribution of sufficient oxygen from inactive to active muscles is essential for optimal exercise performance, no study investigated the effects of nitrate supplementation on muscle oxygenation profiles between active and inactive muscles. Nine healthy males performed 25 min of submaximal (heart rate ~140 bpm; EXsub) and incremental cycling (EXmax) until exhaustion under three conditions: (A) normoxia without drink; (B) hypoxia (FiO2 = 13.95%) with placebo (PL); and (c) hypoxia with beetroot juice (BR). PL and BR were provided for 4 days. Oxygenated and deoxygenated hemoglobin (HbO2 and HHb) were measured in vastus lateralis (active) and biceps brachii (inactive) muscles, and the oxygen saturation of skeletal muscle (StO2; HbO2/total Hb) were calculated. During EXsub, BR suppressed the HHb increases in active muscles during the last 5 min of exercise. During EXmax, time to exhaustion with BR (513 ± 24 sec) was significantly longer than with PL (490 ± 39 sec, P < 0.05). In active muscles, BR suppressed the HHb increases at moderate work rates during EXmax compared to PL (P < 0.05). In addition, BR supplementation was associated with greater reductions in HbO2 and StO2 at higher work rates in inactive muscles during EXmax. Collectively, these findings indicate that short‐term dietary nitrate supplementation improved hypoxic exercise tolerance, perhaps, due to suppressed increases in HHb in active muscles at moderate work rates. Moreover, nitrate supplementation caused greater reductions in oxygenation in inactive muscle at higher work rates during hypoxic exercise.
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Affiliation(s)
- Masahiro Horiuchi
- Division of Human Environmental Science, Mt. Fuji Research Institute, Fuji-yoshida, Japan
| | - Junko Endo
- Division of Human Environmental Science, Mt. Fuji Research Institute, Fuji-yoshida, Japan
| | - Shohei Dobashi
- Graduate School Department of Interdisciplinary, University of Yamanashi, Kofu, Japan
| | - Yoko Handa
- Division of Human Environmental Science, Mt. Fuji Research Institute, Fuji-yoshida, Japan
| | - Masataka Kiuchi
- Graduate School Department of Interdisciplinary, University of Yamanashi, Kofu, Japan
| | - Katsuhiro Koyama
- Graduate School Department of Interdisciplinary, University of Yamanashi, Kofu, Japan
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17
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Asimakos A, Toumpanakis D, Karatza MH, Vasileiou S, Katsaounou P, Mastora Z, Vassilakopoulos T. Immune cell response to strenuous resistive breathing: comparison with whole body exercise and the effects of antioxidants. Int J Chron Obstruct Pulmon Dis 2018; 13:529-545. [PMID: 29445271 PMCID: PMC5808692 DOI: 10.2147/copd.s154533] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Background/hypothesis Whole body exercise (WBE) changes lymphocyte subset percentages in peripheral blood. Resistive breathing, a hallmark of diseases of airway obstruction, is a form of exercise for the inspiratory muscles. Strenuous muscle contractions induce oxidative stress that may mediate immune alterations following exercise. We hypothesized that inspiratory resistive breathing (IRB) alters peripheral blood lymphocyte subsets and that oxidative stress mediates lymphocyte subpopulation alterations following both WBE and IRB. Patients and methods Six healthy nonathletes performed two WBE and two IRB sessions for 45 minutes at 70% of VO2 maximum and 70% of maximum inspiratory pressure (Pimax), respectively, before and after the administration of antioxidants (vitamins E, A, and C for 75 days, allopurinol for 30 days, and N-acetylcysteine for 3 days). Blood was drawn at baseline, at the end of each session, and 2 hours into recovery. Lymphocyte subsets were determined by flow cytometry. Results Before antioxidant supplementation at both WBE end and IRB end, the natural killer cell percentage increased, the T helper cell (CD3+ CD4+) percentage was reduced, and the CD4/CD8 ratio was depressed, a response which was abolished by antioxidants only after IRB. Furthermore, at IRB end, antioxidants promoted CD8+ CD38+ and blunted cytotoxic T-cell percentage increase. CD8+ CD45RA+ cell percentage changes were blunted after antioxidant supplementation in both WBE and IRB. Conclusion We conclude that IRB produces (as WBE) changes in peripheral blood lymphocyte subsets and that oxidative stress is a major stimulus predominantly for IRB-induced lymphocyte subset alterations.
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Affiliation(s)
- Andreas Asimakos
- GP Livanos and M Simou Laboratories, Thorax Foundation.,Critical Care Department and Pulmonary Unit, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens
| | - Dimitrios Toumpanakis
- GP Livanos and M Simou Laboratories, Thorax Foundation.,Critical Care Department and Pulmonary Unit, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens
| | | | | | - Paraskevi Katsaounou
- GP Livanos and M Simou Laboratories, Thorax Foundation.,Critical Care Department and Pulmonary Unit, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens
| | - Zafeiria Mastora
- GP Livanos and M Simou Laboratories, Thorax Foundation.,Critical Care Department and Pulmonary Unit, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens
| | - Theodoros Vassilakopoulos
- GP Livanos and M Simou Laboratories, Thorax Foundation.,Critical Care Department and Pulmonary Unit, Evangelismos Hospital, Medical School, National and Kapodistrian University of Athens.,3rd Department of Critical Care Medicine, Evgenideion Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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18
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Ouksel H. [Role of therapeutic education for patients with COPD participating in respiratory rehabilitation programs]. REVUE DE PNEUMOLOGIE CLINIQUE 2017; 73:309-315. [PMID: 29122397 DOI: 10.1016/j.pneumo.2017.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/08/2017] [Accepted: 09/10/2017] [Indexed: 06/07/2023]
Abstract
National and international guidelines confirm that therapeutic education should be an integral part of respiratory rehabilitation programs. Here we outline the pathophysiological foundation of respiratory rehabilitation in order to better apprehend the underlying rationale while taking into consideration each patient's symptoms, the real justification of any therapeutic intervention. Therapeutic education points out the fact that it is the patient who is being treated, not the illness. It is also the occasion to recall that long-term efficacy implies patient-centered interventions. Therapeutic education thus plays a central role in respiratory rehabilitation. It is implicated in all phases of rehabilitation and particularly for disease-specific indications. It optimizes the chances of long-term success, a clinical, if not evidence-based, observation.
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Affiliation(s)
- H Ouksel
- Département de pneumologie, 04, rue Larrey, 49933 Angers cedex 9, France.
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19
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Iepsen UW, Munch GW, Ryrsø CK, Secher NH, Lange P, Thaning P, Pedersen BK, Mortensen SP. Muscle α-adrenergic responsiveness during exercise and ATP-induced vasodilation in chronic obstructive pulmonary disease patients. Am J Physiol Heart Circ Physiol 2017; 314:H180-H187. [PMID: 29030339 DOI: 10.1152/ajpheart.00398.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathetic vasoconstriction is blunted in exercising muscle (functional sympatholysis) but becomes attenuated with age. We tested the hypothesis that functional sympatholysis is further impaired in chronic obstructive pulmonary disease (COPD) patients. We determined leg blood flow and calculated leg vascular conductance (LVC) during 1) femoral-arterial Tyramine infusion (evokes endogenous norepinephrine release, 1 µmol·min-1·kg leg mass-1), 2) one-legged knee extensor exercise with and without Tyramine infusion [10 W and 20% of maximal workload (WLmax)], 3) ATP (0.05 µmol·min-1·kg leg mass-1) and Tyramine infusion, and 4) incremental ATP infusions (0.05, 0.3, and 3.0 µmol·min-1·kg leg mass-1). We included 10 patients with moderate to severe COPD and 8 age-matched healthy control subjects. Overall, leg blood flow and LVC were lower in COPD patients during exercise ( P < 0.05). Tyramine reduced LVC in both groups at 10-W exercise (COPD: -3 ± 1 ml·min-1·mmHg-1 and controls: -3 ± 1 ml·min-1·mmHg-1, P < 0.05) and 20% WLmax (COPD: -4 ± 1 ml·min-1·mmHg-1 and controls: -3 ± 1 ml·min-1·mmHg-1, P < 0.05) with no difference between groups. Incremental ATP infusions induced dose-dependent vasodilation with no difference between groups, and, in addition, the vasoconstrictor response to Tyramine infused together with ATP was not different between groups (COPD: -0.03 ± 0.01 l·min-1·kg leg mass-1 vs. CONTROLS -0.04 ± 0.01 l·min-1·kg leg mass-1, P > 0.05). Compared with age-matched healthy control subjects, the vasodilatory response to ATP is intact in COPD patients and their ability to blunt sympathetic vasoconstriction (functional sympatholysis) as evaluated by intra-arterial Tyramine during exercise or ATP infusion is maintained. NEW & NOTEWORTHY The ability to blunt sympathetic vasoconstriction in exercising muscle and ATP-induced dilation in chronic obstructive pulmonary disease patients remains unexplored. Chronic obstructive pulmonary disease patients demonstrated similar sympathetic vasoconstriction in response to intra-arterial Tyramine during exercise and ATP-induced vasodilation compared with age-matched healthy control subjects.
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Affiliation(s)
- U W Iepsen
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark
| | - G W Munch
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark
| | - C K Ryrsø
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark
| | - N H Secher
- Department of Anesthesiology, The Copenhagen Muscle Research Centre, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark
| | - P Lange
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark.,Medical Department O, Respiratory Section, Herlev and Gentofte Hospital, Copenhagen , Denmark.,Department of Public Health, Section of Social Medicine, University of Copenhagen , Copenhagen , Denmark
| | - P Thaning
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark.,Medical Department O, Respiratory Section, Herlev and Gentofte Hospital, Copenhagen , Denmark
| | - B K Pedersen
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark
| | - S P Mortensen
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, University of Copenhagen, Rigshospitalet, Copenhagen , Denmark.,Department of Cardiovascular and Renal Research, University of Southern Denmark, Denmark
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20
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Dominelli PB, Archiza B, Ramsook AH, Mitchell RA, Peters CM, Molgat-Seon Y, Henderson WR, Koehle MS, Boushel R, Sheel AW. Effects of respiratory muscle work on respiratory and locomotor blood flow during exercise. Exp Physiol 2017; 102:1535-1547. [DOI: 10.1113/ep086566] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Accepted: 08/21/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Paolo B. Dominelli
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
| | - Bruno Archiza
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
- Department of Physical Therapy; Federal University of São Carlos; São Carlos São Paulo Brazil
| | - Andrew H. Ramsook
- Centre for Heart Lung Innovation, Providence Health Care Research Institute; University of British Columbia; Vancouver BC Canada
| | - Reid A. Mitchell
- Centre for Heart Lung Innovation, Providence Health Care Research Institute; University of British Columbia; Vancouver BC Canada
| | - Carli M. Peters
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
| | | | | | - Michael S. Koehle
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
- Faculty of Medicine; University of British Columbia; Vancouver BC Canada
| | - Robert Boushel
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
| | - A. William Sheel
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
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21
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Moreno AM, Toledo-Arruda AC, Lima JS, Duarte CS, Villacorta H, Nóbrega AC. Inspiratory Muscle Training Improves Intercostal and Forearm Muscle Oxygenation in Patients With Chronic Heart Failure: Evidence of the Origin of the Respiratory Metaboreflex. J Card Fail 2017; 23:672-679. [DOI: 10.1016/j.cardfail.2017.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 04/13/2017] [Accepted: 05/05/2017] [Indexed: 10/19/2022]
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Peters CM, Welch JF, Dominelli PB, Molgat-Seon Y, Romer LM, McKenzie DC, Sheel AW. Influence of inspiratory resistive loading on expiratory muscle fatigue in healthy humans. Exp Physiol 2017. [PMID: 28646592 DOI: 10.1113/ep086346] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
NEW FINDINGS What is the central question of this study? This study is the first to measure objectively both inspiratory and expiratory muscle fatigue after inspiratory resistive loading to determine whether the expiratory muscles are activated to the point of fatigue when specifically loading the inspiratory muscles. What is the main finding and its importance? The absence of abdominal muscle fatigue suggests that future studies attempting to understand the neural and circulatory consequences of diaphragm fatigue can use inspiratory resistive loading without considering the confounding effects of abdominal muscle fatigue. Expiratory resistive loading elicits inspiratory as well as expiratory muscle fatigue, suggesting parallel coactivation of the inspiratory muscles during expiration. It is unknown whether the expiratory muscles are likewise coactivated to the point of fatigue during inspiratory resistive loading (IRL). The purpose of this study was to determine whether IRL elicits expiratory as well as inspiratory muscle fatigue. Healthy male subjects (n = 9) underwent isocapnic IRL (60% maximal inspiratory pressure, 15 breaths min-1 , 0.7 inspiratory duty cycle) to task failure. Abdominal and diaphragm contractile function was assessed at baseline and at 3, 15 and 30 min post-IRL by measuring gastric twitch pressure (Pga,tw ) and transdiaphragmatic twitch pressure (Pdi,tw ) in response to potentiated magnetic stimulation of the thoracic and phrenic nerves, respectively. Fatigue was defined as a significant reduction from baseline in Pga,tw or Pdi,tw . Throughout IRL, there was a time-dependent increase in cardiac frequency and mean arterial blood pressure, suggesting activation of the respiratory muscle metaboreflex. The Pdi,tw was significantly lower than baseline (34.3 ± 9.6 cmH2 O) at 3 (23.2 ± 5.7 cmH2 O, P < 0.001), 15 (24.2 ± 5.1 cmH2 O, P < 0.001) and 30 min post-IRL (26.3 ± 6.0 cmH2 O, P < 0.001). The Pga,tw was not significantly different from baseline (37.6 ± 17.1 cmH2 O) at 3 (36.5 ± 14.6 cmH2 O), 15 (33.7 ± 12.4 cmH2 O) and 30 min post-IRL (32.9 ± 11.3 cmH2 O). Inspiratory resistive loading elicits objective evidence of diaphragm, but not abdominal, muscle fatigue. Agonist-antagonist interactions for the respiratory muscles appear to be more important during expiratory versus inspiratory loading.
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Affiliation(s)
- Carli M Peters
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Joseph F Welch
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Paolo B Dominelli
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Yannick Molgat-Seon
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Lee M Romer
- Centre for Human Performance, Exercise and Rehabilitation, College of Health and Life Sciences, Brunel University London, Uxbridge, UK.,Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge, UK
| | - Donald C McKenzie
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Faculty of Medicine, Division of Sports Medicine, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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23
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Klenze H, Köhler TC, Farquharson F, Walterspacher S, Duerschmied D, Roecker K, Kabitz HJ, Walker DJ. Resting limb muscle perfusion during inspiratory muscle loading in hypoxia and normoxia. Respir Physiol Neurobiol 2017. [PMID: 28625661 DOI: 10.1016/j.resp.2017.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Fatiguing of respiratory muscles reduces peripheral muscle perfusion. Further, acute hypoxia enhances respiratory muscle fatigue. This study investigated the effects of inspiratory muscle loading (IML) on resting locomotor muscle perfusion in hypoxia compared to normoxia. METHODS Ten subjects completed two study days of fatiguing IML (blinded, randomized) in normobaric hypoxia (targeted oxygen saturation 80%) and normoxia, respectively. Contrast-enhanced ultrasound (CEUS) of the gastrocnemius muscle and popliteal doppler ultrasonography were used to monitor muscle perfusion. Based on CEUS and monitored cardiac output, perfusion surrogate parameters (CLPaer and CLPap) were established. RESULTS Muscle perfusion declines early during IML in normoxia (CLPaer: -54±25%, p<0.01; CLPap: -58±32%, p<0.01) and hypoxia (CLPaer: -43±23%, p<0.01; CLPap: -41±20%, p<0.01). Hypoxia compared to normoxia increased cardiac output before (+23±19%, p<0.01 ANOVA) and during (+22±20%, p<0.01 ANOVA) IML, while local muscle perfusion during IML remained unchanged (CLPaer: p=0.41 ANOVA; CLPap: p=0.29 ANOVA). CONCLUSION Acute hypoxia compared to normoxia does not affect locomotor muscle perfusion during fatiguing IML.
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Affiliation(s)
- Hannes Klenze
- Department of Pneumology and Intensive Care Medicine, Academic Teaching Hospital Klinikum Konstanz, Germany.
| | | | - Franziska Farquharson
- Department of Pneumology and Intensive Care Medicine, Academic Teaching Hospital Klinikum Konstanz, Germany
| | - Stephan Walterspacher
- Department of Pneumology and Intensive Care Medicine, Academic Teaching Hospital Klinikum Konstanz, Germany; Department of Medicine/Pneumology, Faculty of Health, Witten/Herdecke University, Witten, Germany
| | - Daniel Duerschmied
- Cardiology and Angiology I, University Heart Center Freiburg - Bad Krozingen and Interdisciplinary Medical Intensive Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Kai Roecker
- Department of Applied Public Health (AGW), Furtwangen University, Germany
| | - Hans-Joachim Kabitz
- Department of Pneumology and Intensive Care Medicine, Academic Teaching Hospital Klinikum Konstanz, Germany
| | - David Johannes Walker
- Department of Pneumology and Intensive Care Medicine, Academic Teaching Hospital Klinikum Konstanz, Germany; Department of Medicine/Pneumology, Faculty of Health, Witten/Herdecke University, Witten, Germany
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24
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Smith JR, Didier KD, Hammer SM, Alexander AM, Kurti SP, Copp SW, Barstow TJ, Harms CA. Effect of cyclooxygenase inhibition on the inspiratory muscle metaboreflex-induced cardiovascular consequences in men. J Appl Physiol (1985) 2017; 123:197-204. [PMID: 28522759 DOI: 10.1152/japplphysiol.00165.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/03/2017] [Accepted: 05/10/2017] [Indexed: 12/25/2022] Open
Abstract
Inspiratory muscle metaboreflex activation increases mean arterial pressure (MAP) and limb vascular resistance (LVR) and decreases limb blood flow (Q̇L). Cyclooxygenase (COX) inhibition has been found to attenuate limb skeletal muscle metaboreflex-induced increases in muscle sympathetic nerve activity. We hypothesized that compared with placebo (PLA), COX inhibition would attenuate inspiratory muscle metaboreflex-induced 1) increases in MAP and LVR and 2) decreases in Q̇L Seven men (22 ± 1 yr) were recruited and orally consumed ibuprofen (IB; 10 mg/kg) or PLA 90 min before performing the cold pressor test (CPT) for 2 min and inspiratory resistive breathing task (IRBT) for 14.9 ± 2.0 min at 65% of maximal inspiratory pressure. Breathing frequency was 20 breaths/min with a 50% duty cycle during the IRBTs. MAP was measured via automated oscillometry, Q̇L was determined via Doppler ultrasound, and LVR was calculated as MAP divided by Q̇L Electromyography was recorded on the leg to ensure no muscle contraction occurred. The 65% IRBT led to greater increases (P = 0.02) in 6-keto-prostaglandin-F1α with PLA compared with IB. IB, compared with PLA, led to greater (P < 0.01) increases in MAP (IB: 17 ± 7 mmHg vs. PLA: 8 ± 5 mmHg) and LVR (IB: 69 ± 28% vs. PLA: 52 ± 22%) at the final minute of the 65% IRBT. The decrease in Q̇L was not different (P = 0.72) between IB (-28 ± 11%) and PLA (-27 ± 9%) at the final minute. The increase in MAP during the CPT was not different (P = 0.87) between IB (25 ± 11 mmHg) and PLA (24 ± 6 mmHg). Contrary to our hypotheses, COX inhibition led to greater inspiratory muscle metaboreflex-induced increases in MAP and LVR.NEW & NOTEWORTHY Cyclooxygenase (COX) products play a role in activating the muscle metaboreflex. It is not known whether COX products contribute to the inspiratory muscle metaboreflex. Herein, we demonstrate that COX inhibition led to greater increases in blood pressure and limb vascular resistance compared with placebo during inspiratory muscle metaboreflex activation.
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Affiliation(s)
- Joshua R Smith
- Department of Kinesiology, Kansas State University, Manhattan Kansas
| | - Kaylin D Didier
- Department of Kinesiology, Kansas State University, Manhattan Kansas
| | - Shane M Hammer
- Department of Kinesiology, Kansas State University, Manhattan Kansas
| | | | - Stephanie P Kurti
- Department of Kinesiology, Kansas State University, Manhattan Kansas
| | - Steven W Copp
- Department of Kinesiology, Kansas State University, Manhattan Kansas
| | - Thomas J Barstow
- Department of Kinesiology, Kansas State University, Manhattan Kansas
| | - Craig A Harms
- Department of Kinesiology, Kansas State University, Manhattan Kansas
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Smith JR, Alexander AM, Hammer SM, Didier KD, Kurti SP, Broxterman RM, Barstow TJ, Harms CA. Cardiovascular consequences of the inspiratory muscle metaboreflex: effects of age and sex. Am J Physiol Heart Circ Physiol 2017; 312:H1013-H1020. [DOI: 10.1152/ajpheart.00818.2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/22/2017] [Accepted: 02/23/2017] [Indexed: 01/15/2023]
Abstract
With inspiratory muscle metaboreflex activation, we hypothesized that, compared with their younger counterparts, older men and women would exhibit greater 1) increases in mean arterial pressure (MAP) and limb vascular resistance (LVR) and 2) decreases in limb blood flow (Q̇L) but 3) no sex differences would be present in older adults. Sixteen young adults [8 young men (YM) and 8 young women (YW), 18–24 yr] and 16 older adults [8 older men (OM) and 8 older women (OW), 60–73 yr] performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths/min with a 50% duty cycle. At baseline and during the IRBTs, MAP was measured via automated oscillometry, Q̇L was determined via Doppler ultrasound, and LVR was calculated. The 65% IRBT led to significantly greater increases in MAP in OW (15.9 ± 8.1 mmHg) compared with YW (6.9 ± 1.4 mmHg) but not ( P > 0.05) between OM (12.3 ± 5.7 mmHg) and YM (10.8 ± 5.7 mmHg). OW (−20.2 ± 7.2%) had greater ( P < 0.05) decreases in Q̇L compared with YW (−9.4 ± 10.2%), but no significant differences were present between OM (−22.8 ± 9.7%) and YM (−22.7 ± 11.3%) during the 65% IRBT. The 65% IRBT led to greater ( P < 0.05) increases in LVR in OW (48.2 ± 25.5%) compared with YW (19.7 ± 15.0%), but no differences ( P > 0.05) existed among OM (54.4 ± 17.8%) and YM (47.1 ± 23.3%). No significant differences were present in MAP, Q̇L, or LVR between OM and OW. These data suggest that OW exhibit a greater inspiratory muscle metaboreflex compared with YW, whereas no differences between OM and YM existed. Finally, sex differences in the inspiratory muscle metaboreflex are not present in older adults. NEW & NOTEWORTHY Premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with young men; however, it is unknown whether these sex differences are present in older adults. Older women exhibited a greater inspiratory muscle metaboreflex compared with premenopausal women, whereas no differences were present between older and younger men.
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Affiliation(s)
- Joshua R. Smith
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Shane M. Hammer
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Kaylin D. Didier
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | | | - Thomas J. Barstow
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Craig A. Harms
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
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Garske LA, Lal R, Stewart IB, Morris NR, Cross TJ, Adams L. Exertional dyspnea associated with chest wall strapping is reduced when external dead space substitutes for part of the exercise stimulus to ventilation. J Appl Physiol (1985) 2017; 122:1179-1187. [DOI: 10.1152/japplphysiol.00051.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 01/30/2017] [Accepted: 01/30/2017] [Indexed: 11/22/2022] Open
Abstract
Chest wall strapping has been used to assess mechanisms of dyspnea with restrictive lung disease. This study examined the hypothesis that dyspnea with restriction depends principally on the degree of reflex ventilatory stimulation. We compared dyspnea at the same (iso)ventilation when added dead space provided a component of the ventilatory stimulus during exercise. Eleven healthy men undertook a randomized controlled crossover trial that compared four constant work exercise conditions: 1) control (CTRL): unrestricted breathing at 90% gas exchange threshold (GET); 2) CTRL+dead space (DS): unrestricted breathing with 0.6-l dead space, at isoventilation to CTRL due to reduced exercise intensity; 3) CWS: chest wall strapping at 90% GET; and 4) CWS+DS: chest strapping with 0.6-l dead space, at isoventilation to CWS with reduced exercise intensity. Chest strapping reduced forced vital capacity by 30.4 ± 2.2% (mean ± SE). Dyspnea at isoventilation was unchanged with CTRL+DS compared with CTRL (1.93 ± 0.49 and 2.17 ± 0.43, 0–10 numeric rating scale, respectively; P = 0.244). Dyspnea was lower with CWS+DS compared with CWS (3.40 ± 0.52 and 4.51 ± 0.53, respectively; P = 0.003). Perceived leg fatigue was reduced with CTRL+DS compared with CTRL (2.36 ± 0.48 and 2.86 ± 0.59, respectively; P = 0.049) and lower with CWS+DS compared with CWS (1.86 ± 0.30 and 4.00 ± 0.79, respectively; P = 0.006). With unrestricted breathing, dead space did not change dyspnea at isoventilation, suggesting that dyspnea does not depend on the mode of reflex ventilatory stimulation in healthy individuals. With chest strapping, dead space presented a less potent stimulus to dyspnea, raising the possibility that leg muscle work contributes to dyspnea perception independent of the ventilatory stimulus. NEW & NOTEWORTHY Chest wall strapping was applied to healthy humans to simulate restrictive lung disease. With chest wall strapping, dyspnea was reduced when dead space substituted for part of a constant exercise stimulus to ventilation. Dyspnea associated with chest wall strapping depended on the contribution of leg muscle work to ventilatory stimulation. Chest wall strapping might not be a clinically relevant model to determine whether an alternative reflex ventilatory stimulus mimics the intensity of exertional dyspnea.
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Affiliation(s)
- Luke A. Garske
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
- Respiratory and Sleep Medicine, Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Ravin Lal
- Allied Health Sciences and Menzies Health Institute of Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Ian B. Stewart
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Norman R. Morris
- Allied Health Sciences and Menzies Health Institute of Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Troy J. Cross
- Allied Health Sciences and Menzies Health Institute of Queensland, Griffith University, Gold Coast, Queensland, Australia
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota; and
| | - Lewis Adams
- Allied Health Sciences and Menzies Health Institute of Queensland, Griffith University, Gold Coast, Queensland, Australia
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Caruso FCR, Simões RP, Reis MS, Guizilini S, Alves VLDS, Papa V, Arena R, Borghi-Silva A. High-Intensity Inspiratory Protocol Increases Heart Rate Variability in Myocardial Revascularization Patients. Braz J Cardiovasc Surg 2016; 31:38-44. [PMID: 27074273 PMCID: PMC5062699 DOI: 10.5935/1678-9741.20160007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 02/05/2016] [Indexed: 11/20/2022] Open
Abstract
Objective: To evaluate heart rate variability during an inspiratory muscle endurance
protocol at three different load levels [30%, 60% and 80% of maximal
inspiratory pressure], in patients who had previously undergone
coronary artery bypass grafting. Methods: Nineteen late postoperative myocardial revascularization patients
participating in a cardiovascular rehabilitation program were studied.
Maximal inspiratory pressure maneuvers were performed. An inspiratory muscle
endurance protocol at 30%, 60% and 80% of maximal inspiratory pressure was
applied for four minutes each, in random order. Heart rate and RR intervals
were recorded and heart rate variability was analyzed by time (RMSSD-the
mean of the standard deviations for all R-R intervals, and RMSM-root-mean
square differences of successive R-R intervals) and frequency domains
indices (high and low frequency) in normalized units. ANOVA for repeated
measurements was used to compare heart rate variability indices and Student
t-test was used to compare the maximal inspiratory pressure and maximal
expiratory pressure values. Results: Heart rate increased during performance of maximal respiratory pressures
maneuvers, and the maximal inspiratory pressure and maximal expiratory
pressure mean values were significantly lower than predicted values
(P<0.05). RMSSD increased significantly at 80% in
relation to rest and 30% of maximal inspiratory pressure and RMSM decreased
at 30% and 60% of maximal inspiratory pressure in relation to rest
(P<0.05). Additionally, there was significant and
progressive decrease in low frequency and increase in high frequency at 30%,
60% and 80% of maximal inspiratory pressure in relation to the resting
condition. Conclusion: These results suggest that respiratory muscle training at high intensities
can promote greater parasympathetic activity and it may confer important
benefits during a rehabilitation program in post-coronary artery bypass
grafting.
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Affiliation(s)
| | - Rodrigo Polaquini Simões
- Laboratory of Cardiopulmonary Physiotherapy, Federal University of São Carlos, São Carlos, SP, Brazil
| | - Michel Silva Reis
- Department of Physiotherapy, Faculty of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Solange Guizilini
- Department of Sciences of Human Movement, Federal University of São Paulo, Santos, SP, Brazil
| | | | - Valeria Papa
- Hospital São Francisco of Ribeirão Preto, Ribeirão Preto, SP, Brazil
| | - Ross Arena
- Department of Physical Therapy and Integrative Physiology Laboratory, College of Applied Health Sciences, University of Illinois Chicago, Chicago, IL, USA
| | - Audrey Borghi-Silva
- Laboratory of Cardiopulmonary Physiotherapy, Federal University of São Carlos, São Carlos, SP, Brazil
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Smith JR, Broxterman RM, Hammer SM, Alexander AM, Didier KD, Kurti SP, Barstow TJ, Harms CA. Sex differences in the cardiovascular consequences of the inspiratory muscle metaboreflex. Am J Physiol Regul Integr Comp Physiol 2016; 311:R574-81. [DOI: 10.1152/ajpregu.00187.2016] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/30/2016] [Indexed: 11/22/2022]
Abstract
It is currently unknown whether sex differences exist in the cardiovascular consequences of the inspiratory muscle metaboreflex. We hypothesized that the activation of the inspiratory muscle metaboreflex will lead to less of an increase in mean arterial pressure (MAP) and limb vascular resistance (LVR) and less of a decrease in limb blood flow (Q̇L) in women compared with men. Twenty healthy men ( n = 10, 23 ± 2 yr) and women ( n = 10, 22 ± 3 yr) were recruited for this study. Subjects performed inspiratory resistive breathing tasks (IRBTs) at 2% or 65% of their maximal inspiratory mouth pressure (PIMAX). During the IRBTs, the breathing frequency was 20 breaths/min with a 50% duty cycle. At rest and during the IRBTs, MAP was measured via automated oscillometry, Q̇L was measured via Doppler ultrasound, and LVR was calculated. EMG was recorded on the leg to ensure no muscle contraction occurred. The 65% IRBT led to attenuated increases ( P < 0.01) from baseline in women compared with men for MAP (W: 7.3 ± 2.0 mmHg; M: 11.1 ± 5.0 mmHg) and LVR (W: 17.7% ± 14.0%; M: 47.9 ± 21.0%), as well as less of a decrease ( P < 0.01) in Q̇L (W: −7.5 ± 9.9%; M: −23.3 ± 10.2%). These sex differences in MAP, Q̇L, and LVR were still present in a subset of subjects matched for PIMAX. The 2% IRBT resulted in no significant changes in MAP, Q̇L, or LVR across time or between men and women. These data indicate premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with age-matched men.
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Affiliation(s)
- Joshua R. Smith
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Shane M. Hammer
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Kaylin D. Didier
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Thomas J. Barstow
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Craig A. Harms
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
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Inspiratory loading and limb blood flow in COPD: The modulating effects of resting lung hyperinflation. Respir Physiol Neurobiol 2016; 228:25-9. [DOI: 10.1016/j.resp.2016.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 02/22/2016] [Accepted: 03/03/2016] [Indexed: 11/18/2022]
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Fan JL, Kayser B. Fatigue and Exhaustion in Hypoxia: The Role of Cerebral Oxygenation. High Alt Med Biol 2016; 17:72-84. [DOI: 10.1089/ham.2016.0034] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Affiliation(s)
- Jui-Lin Fan
- Centre for Translational Physiology, University of Otago, Wellington, New Zealand
- Department of Surgery & Anaesthesia, University of Otago, Wellington, New Zealand
| | - Bengt Kayser
- Institute of Sports Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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31
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Gravier FÉ, Bonnevie T, Medrinal C, Debeaumont D, Dupuis J, Viacroze C, Muir JF, Tardif C. Ventilation non invasive au cours de la réhabilitation respiratoire des patients atteints de BPCO. Rev Mal Respir 2016; 33:422-30. [DOI: 10.1016/j.rmr.2015.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 09/07/2015] [Indexed: 10/22/2022]
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Phillips DB, Stickland MK, Petersen SR. Ventilatory responses to prolonged exercise with heavy load carriage. Eur J Appl Physiol 2015; 116:19-27. [DOI: 10.1007/s00421-015-3240-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 08/07/2015] [Indexed: 10/23/2022]
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Spruit MA, Singh SJ, Garvey C, ZuWallack R, Nici L, Rochester C, Hill K, Holland AE, Lareau SC, Man WDC, Pitta F, Sewell L, Raskin J, Bourbeau J, Crouch R, Franssen FME, Casaburi R, Vercoulen JH, Vogiatzis I, Gosselink R, Clini EM, Effing TW, Maltais F, van der Palen J, Troosters T, Janssen DJA, Collins E, Garcia-Aymerich J, Brooks D, Fahy BF, Puhan MA, Hoogendoorn M, Garrod R, Schols AMWJ, Carlin B, Benzo R, Meek P, Morgan M, Rutten-van Mölken MPMH, Ries AL, Make B, Goldstein RS, Dowson CA, Brozek JL, Donner CF, Wouters EFM. An official American Thoracic Society/European Respiratory Society statement: key concepts and advances in pulmonary rehabilitation. Am J Respir Crit Care Med 2013; 188:e13-64. [PMID: 24127811 DOI: 10.1164/rccm.201309-1634st] [Citation(s) in RCA: 2099] [Impact Index Per Article: 190.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Pulmonary rehabilitation is recognized as a core component of the management of individuals with chronic respiratory disease. Since the 2006 American Thoracic Society (ATS)/European Respiratory Society (ERS) Statement on Pulmonary Rehabilitation, there has been considerable growth in our knowledge of its efficacy and scope. PURPOSE The purpose of this Statement is to update the 2006 document, including a new definition of pulmonary rehabilitation and highlighting key concepts and major advances in the field. METHODS A multidisciplinary committee of experts representing the ATS Pulmonary Rehabilitation Assembly and the ERS Scientific Group 01.02, "Rehabilitation and Chronic Care," determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant clinical and scientific expertise. The final content of this Statement was agreed on by all members. RESULTS An updated definition of pulmonary rehabilitation is proposed. New data are presented on the science and application of pulmonary rehabilitation, including its effectiveness in acutely ill individuals with chronic obstructive pulmonary disease, and in individuals with other chronic respiratory diseases. The important role of pulmonary rehabilitation in chronic disease management is highlighted. In addition, the role of health behavior change in optimizing and maintaining benefits is discussed. CONCLUSIONS The considerable growth in the science and application of pulmonary rehabilitation since 2006 adds further support for its efficacy in a wide range of individuals with chronic respiratory disease.
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Abstract
During dynamic exercise, the healthy pulmonary system faces several major challenges, including decreases in mixed venous oxygen content and increases in mixed venous carbon dioxide. As such, the ventilatory demand is increased, while the rising cardiac output means that blood will have considerably less time in the pulmonary capillaries to accomplish gas exchange. Blood gas homeostasis must be accomplished by precise regulation of alveolar ventilation via medullary neural networks and sensory reflex mechanisms. It is equally important that cardiovascular and pulmonary system responses to exercise be precisely matched to the increase in metabolic requirements, and that the substantial gas transport needs of both respiratory and locomotor muscles be considered. Our article addresses each of these topics with emphasis on the healthy, young adult exercising in normoxia. We review recent evidence concerning how exercise hyperpnea influences sympathetic vasoconstrictor outflow and the effect this might have on the ability to perform muscular work. We also review sex-based differences in lung mechanics.
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Affiliation(s)
- Andrew William Sheel
- The School of Kinesiology, The University of British Columbia, Vancouver, Canada.
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36
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Wüthrich TU, Notter DA, Spengler CM. Effect of inspiratory muscle fatigue on exercise performance taking into account the fatigue-induced excess respiratory drive. Exp Physiol 2013; 98:1705-17. [DOI: 10.1113/expphysiol.2013.073635] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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37
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McConnell AK. CrossTalk opposing view: respiratory muscle training does improve exercise tolerance. J Physiol 2013; 590:3397-8; discussion 3399-400. [PMID: 22855045 DOI: 10.1113/jphysiol.2012.235572] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Alison K McConnell
- Centre for Sports Medicine and Human Performance, Brunel University, London UB8 3PH,
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38
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Limberg JK, Morgan BJ, Schrage WG, Dempsey JA. Respiratory influences on muscle sympathetic nerve activity and vascular conductance in the steady state. Am J Physiol Heart Circ Physiol 2013; 304:H1615-23. [PMID: 23585141 DOI: 10.1152/ajpheart.00112.2013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In patients with hypertension, volitional slowing of the respiratory rate has been purported to reduce arterial pressure via withdrawal of sympathetic tone. We examined the effects of paced breathing at 7, 14, and 21 breaths/min, with reciprocal changes in tidal volume, on muscle sympathetic nerve activity, forearm blood flow, forearm vascular conductance, and blood pressure in 21 men and women, 8 of whom had modest elevations in systemic arterial pressure. These alterations in breathing frequency and volume did not affect steady-state levels of sympathetic activity, blood flow, vascular conductance, or blood pressure (all P > 0.05), even though they had the expected effect on sympathetic activity within breaths (i.e., increased modulation during low-frequency/high-tidal volume breathing) (P < 0.001). These findings were consistent across subjects with widely varied baseline levels of sympathetic activity (4-fold), mean arterial pressure (78-110 mmHg), and vascular conductance (15-fold), and those who became hypocapnic during paced breathing vs. those who maintained normocapnia. These findings challenge the notion that slow, deep breathing lowers arterial pressure by suppressing steady-state sympathetic outflow.
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Affiliation(s)
- Jacqueline K Limberg
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, School of Education, University of Wisconsin, Madison, WI, USA
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Janssens L, Brumagne S, McConnell AK, Raymaekers J, Goossens N, Gayan-Ramirez G, Hermans G, Troosters T. The assessment of inspiratory muscle fatigue in healthy individuals: A systematic review. Respir Med 2013; 107:331-46. [DOI: 10.1016/j.rmed.2012.11.019] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 11/15/2012] [Indexed: 01/11/2023]
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Inspiratory loading and limb locomotor and respiratory muscle deoxygenation during cycling exercise. Respir Physiol Neurobiol 2012; 185:506-14. [PMID: 23228896 DOI: 10.1016/j.resp.2012.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Revised: 11/26/2012] [Accepted: 11/29/2012] [Indexed: 11/20/2022]
Abstract
The aim of this study was to determine the effect of inspiratory loading on limb locomotor (LM) and respiratory muscle (RM) deoxygenation ([deoxy (Hb+Mb)]) using NIRS during constant-power cycling exercise. Sixteen, male cyclists completed three, 6-min trials. The intensity of the first 3-min of each trial was equivalent to ~80% V(O(2max)) (EX(80%)); during the final 3-min, subjects received an intervention consisting of either moderate inspiratory loading (Load(mod)), heavy inspiratory loading (Load(heavy)), or maximal exercise (Load(EX)). Load(heavy) significantly increased LM [deoxy(Hb+Mb)] from 12.2±9.0 μm during EX(80%) to 15.3±11.7 μm, and RM [deoxy(Hb+Mb)] from 5.9±3.6 μm to 9.5±6.6 μm. LM and RM [deoxy(Hb+Mb)] were significantly increased from EX(80%) to Load(EX); 12.8±9.1 μm to 16.4±10.3 μm and 5.9±2.9 μm to 11.0±6.4 μm, respectively. These data suggest an increase in respiratory muscle load increases muscle deoxy(Hb+Mb) and thus may indicate a reduction in oxygen delivery and/or increased oxygen extraction by the active muscles.
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Dempsey JA. New perspectives concerning feedback influences on cardiorespiratory control during rhythmic exercise and on exercise performance. J Physiol 2012; 590:4129-44. [PMID: 22826128 DOI: 10.1113/jphysiol.2012.233908] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The cardioaccelerator and ventilatory responses to rhythmic exercise in the human are commonly viewed as being mediated predominantly via feedforward 'central command' mechanisms, with contributions from locomotor muscle afferents to the sympathetically mediated pressor response. We have assessed the relative contributions of three types of feedback afferents on the cardiorespiratory response to voluntary, rhythmic exercise by inhibiting their normal 'tonic' activity in healthy animals and humans and in chronic heart failure. Transient inhibition of the carotid chemoreceptors during moderate intensity exercise reduced muscle sympathetic nerve activity (MSNA) and increased limb vascular conductance and blood flow; and reducing the normal level of respiratory muscle work during heavier intensity exercise increased limb vascular conductance and blood flow. These cardiorespiratory effects were prevented via ganglionic blockade and were enhanced in chronic heart failure and in hypoxia. Blockade of μ opioid sensitive locomotor muscle afferents, with preservation of central motor output via intrathecal fentanyl: (a) reduced the mean arterial blood pressure (MAP), heart rate and ventilatory responses to all steady state exercise intensities; and (b) during sustained high intensity exercise, reduced O(2) transport, increased central motor output and end-exercise muscle fatigue and reduced endurance performance. We propose that these three afferent reflexes - probably acting in concert with feedforward central command - contribute significantly to preserving O(2) transport to locomotor and to respiratory muscles during exercise. Locomotor muscle afferents also appear to provide feedback concerning the metabolic state of the muscle to influence central motor output, thereby limiting peripheral fatigue development.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin - Madison, 1300 University Ave, Room 4245 MSC, Madison, WI 53706-1532, USA.
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42
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Limitations of respiratory muscle and vastus lateralis blood flow during continuous exercise. Respir Physiol Neurobiol 2012; 181:302-7. [DOI: 10.1016/j.resp.2012.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 04/02/2012] [Accepted: 04/03/2012] [Indexed: 11/24/2022]
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Katayama K, Iwamoto E, Ishida K, Koike T, Saito M. Inspiratory muscle fatigue increases sympathetic vasomotor outflow and blood pressure during submaximal exercise. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1167-75. [PMID: 22461178 DOI: 10.1152/ajpregu.00006.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to elucidate the influence of inspiratory muscle fatigue on muscle sympathetic nerve activity (MSNA) and blood pressure (BP) response during submaximal exercise. We hypothesized that inspiratory muscle fatigue would elicit increases in sympathetic vasoconstrictor outflow and BP during dynamic leg exercise. The subjects carried out four submaximal exercise tests: two were maximal inspiratory pressure (PI(max)) tests and two were MSNA tests. In the PI(max) tests, the subjects performed two 10-min exercises at 40% peak oxygen uptake using a cycle ergometer in a semirecumbent position [spontaneous breathing for 5 min and with or without inspiratory resistive breathing for 5 min (breathing frequency: 60 breaths/min, inspiratory and expiratory times were each set at 0.5 s)]. Before and immediately after exercise, PI(max) was estimated. In MSNA tests, the subjects performed two 15-min exercises (spontaneous breathing for 5 min, with or without inspiratory resistive breathing for 5 min, and spontaneous breathing for 5 min). MSNA was recorded via microneurography of the right median nerve at the elbow. PI(max) decreased following exercise with resistive breathing, whereas no change was found without resistance. The time-dependent increase in MSNA burst frequency (BF) appeared during exercise with inspiratory resistive breathing, accompanied by an augmentation of diastolic BP (DBP) (with resistance: MSNA, BF +83.4%; DBP, +23.8%; without resistance: MSNA BF, +19.2%; DBP, -0.4%, from spontaneous breathing during exercise). These results suggest that inspiratory muscle fatigue induces increases in muscle sympathetic vasomotor outflow and BP during dynamic leg exercise at mild intensity.
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Affiliation(s)
- Keisho Katayama
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan.
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Forbes S, Game A, Syrotuik D, Jones R, Bell GJ. The Effect of Inspiratory and Expiratory Respiratory Muscle Training in Rowers. Res Sports Med 2011; 19:217-30. [DOI: 10.1080/15438627.2011.608033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- S. Forbes
- a Faculty of Physical Education & Recreation , University of Alberta , Edmonton, Alberta, Canada
| | - A. Game
- a Faculty of Physical Education & Recreation , University of Alberta , Edmonton, Alberta, Canada
| | - D. Syrotuik
- a Faculty of Physical Education & Recreation , University of Alberta , Edmonton, Alberta, Canada
| | - R. Jones
- b Faculty of Medicine , University of Alberta , Edmonton, Alberta, Canada
| | - G. J. Bell
- a Faculty of Physical Education & Recreation , University of Alberta , Edmonton, Alberta, Canada
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Shadgan B, Guenette JA, Sheel AW, Reid WD. Sternocleidomastoid muscle deoxygenation in response to incremental inspiratory threshold loading measured by near infrared spectroscopy. Respir Physiol Neurobiol 2011; 178:202-9. [DOI: 10.1016/j.resp.2011.06.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 05/31/2011] [Accepted: 06/03/2011] [Indexed: 10/18/2022]
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46
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Attenuated inspiratory muscle metaboreflex in endurance-trained individuals. Respir Physiol Neurobiol 2011; 177:24-9. [DOI: 10.1016/j.resp.2011.03.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 02/28/2011] [Accepted: 03/01/2011] [Indexed: 11/19/2022]
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Effect of inspiratory muscle training intensities on pulmonary function and work capacity in people who are healthy: a randomized controlled trial. Phys Ther 2011; 91:894-905. [PMID: 21493747 DOI: 10.2522/ptj.20090413] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Inspiratory muscle training (IMT) has been shown to improve inspiratory muscle function, lung volumes (vital capacity [VC] and total lung capacity [TLC]), work capacity, and power output in people who are healthy; however, no data exist that demonstrate the effect of varying intensities of IMT to produce these outcomes. OBJECTIVES The purpose of this study was to evaluate the impact of IMT at varying intensities on inspiratory muscle function, VC, TLC, work capacity, and power output in people who are healthy. DESIGN This was a randomized controlled trial. SETTING The study was conducted in a clinical laboratory. PARTICIPANTS Forty people who were healthy (mean age=21.7 years) were randomly assigned to 4 groups of 10 individuals. INTERVENTIONS Three of the groups completed an 8-week program of IMT set at 80%, 60%, and 40% of sustained maximum inspiratory effort. Training was performed 3 days per week, with 24 hours separating training sessions. A control group did not participate in any form of training. MEASUREMENTS Baseline and posttraining measurements of body composition, VC, TLC, inspiratory muscle function (including maximum inspiratory pressure [MIP] and sustained maximum inspiratory pressure [SMIP]), work capacity (minutes of exercise), and power output were obtained. RESULTS The participants in the 80%, 60%, and 40% training groups demonstrated significant increases in MIP and SMIP, whereas those in the 80% and 60% training groups had increased work capacity and power output. Only the 80% group improved their VC and TLC. The control group demonstrated no change in any outcome measures. LIMITATIONS This study may have been underpowered to demonstrate improved work capacity and power output in individuals who trained at 40% of sustained maximum inspiratory effort. CONCLUSION High-intensity IMT set at 80% of maximal effort resulted in increased MIP and SMIP, lung volumes, work capacity, and power output in individuals who were healthy, whereas IMT at 60% of maximal effort increased work capacity and power output only. Inspiratory muscle training intensities lower than 40% of maximal effort do not translate into quantitative functional outcomes.
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Keramidas ME, Kounalakis SN, Eiken O, Mekjavic IB. Muscle and cerebral oxygenation during exercise performance after short-term respiratory work. Respir Physiol Neurobiol 2011; 175:247-54. [DOI: 10.1016/j.resp.2010.11.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 11/19/2010] [Accepted: 11/19/2010] [Indexed: 11/25/2022]
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MccONNELL ALISONK, GRIFFITHS LISAA. Acute Cardiorespiratory Responses to Inspiratory Pressure Threshold Loading. Med Sci Sports Exerc 2010; 42:1696-703. [DOI: 10.1249/mss.0b013e3181d435cf] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bailey SJ, Romer LM, Kelly J, Wilkerson DP, DiMenna FJ, Jones AM. Inspiratory muscle training enhances pulmonary O(2) uptake kinetics and high-intensity exercise tolerance in humans. J Appl Physiol (1985) 2010; 109:457-68. [PMID: 20507969 DOI: 10.1152/japplphysiol.00077.2010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fatigue of the respiratory muscles during intense exercise might compromise leg blood flow, thereby constraining oxygen uptake (Vo(2)) and limiting exercise tolerance. We tested the hypothesis that inspiratory muscle training (IMT) would reduce inspiratory muscle fatigue, speed Vo(2) kinetics and enhance exercise tolerance. Sixteen recreationally active subjects (mean + or - SD, age 22 + or - 4 yr) were randomly assigned to receive 4 wk of either pressure threshold IMT [30 breaths twice daily at approximately 50% of maximum inspiratory pressure (MIP)] or sham treatment (60 breaths once daily at approximately 15% of MIP). The subjects completed moderate-, severe- and maximal-intensity "step" exercise transitions on a cycle ergometer before (Pre) and after (Post) the 4-wk intervention period for determination of Vo(2) kinetics and exercise tolerance. There were no significant changes in the physiological variables of interest after Sham. After IMT, baseline MIP was significantly increased (Pre vs. Post: 155 + or - 22 vs. 181 + or - 21 cmH(2)O; P < 0.001), and the degree of inspiratory muscle fatigue was reduced after severe- and maximal-intensity exercise. During severe exercise, the Vo(2) slow component was reduced (Pre vs. Post: 0.60 + or - 0.20 vs. 0.53 + or - 0.24 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 765 + or - 249 vs. 1,061 + or - 304 s; P < 0.01). Similarly, during maximal exercise, the Vo(2) slow component was reduced (Pre vs. Post: 0.28 + or - 0.14 vs. 0.18 + or - 0.07 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 177 + or - 24 vs. 208 + or - 37 s; P < 0.01). Four weeks of IMT, which reduced inspiratory muscle fatigue, resulted in a reduced Vo(2) slow-component amplitude and an improved exercise tolerance during severe- and maximal-intensity exercise. The results indicate that the enhanced exercise tolerance observed after IMT might be related, at least in part, to improved Vo(2) dynamics, presumably as a consequence of increased blood flow to the exercising limbs.
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Affiliation(s)
- Stephen J Bailey
- School of Sport and Health Sciences, St. Luke's Campus, Univ. of Exeter, Heavitree Road, Exeter, Devon EX1 2LU, UK
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