Effects of hypoxia on exercise‐induced diaphragm fatigue in healthy males and females

Reinhard, Paige A.; Archiza, Bruno; Welch, Joseph F.; Benbaruj, Jenna; Guenette, Jordan A.; Koehle, Michael S.; Sheel, A. William

doi:10.14814/phy2.15589

Cited by 4 publications

(4 citation statements)

References 39 publications

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“…Chest-wall restriction during submaximal exercise elicited an increase in trueV̇normalE (~8 L·min −1 ) and trueẆnormalB (~230 J·min −1 ), resulting in greater diaphragm fatigue than unrestricted exercise (16). Moreover, the magnitude of reduction in diaphragm pressure generating capacity (−23% diaphragmatic pressure) with chest-wall strapping during submaximal exercise is consistent with that seen with exhaustive exercise and the associated decrements in exercise performance (17–19). These data could potentially indicate that even mild chest-wall restriction (i.e., via a sports bra underband) can influence the levels of respiratory muscle work and time to exhaustion.…”

Section: Discussionsupporting

confidence: 66%

Sports Bra Restriction on Respiratory Mechanics during Exercise

KIPP,

LEAHY,

SHEEL

2024

Medicine &Amp; Science in Sports &Amp; Exercise

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Women perform exercise in sports bras to limit breast motion. However, as the breasts become restricted, respiratory function may become compromised. Purpose We set out to understand how underband tightness or pressure of a sports bra relates to respiratory function and the mechanical work of breathing ( during exercise. Our secondary purpose was to quantify the effects of underband pressure on O2 during submaximal running. Methods Nine highly trained, female runners with normal pulmonary function completed maximal and submaximal running in three levels of underband restriction: loose, self-selected, and tight. Results During maximal exercise, we observed a significantly greater during the tight condition (350 ± 78 J/min) compared to the loose condition (301 ± 78 J/min; p < 0.05), and a 5% increase in minute ventilation ( ) during the tight condition compared to the loose condition (p < 0.05). The pattern of breathing also differed between the two conditions; the greater maximal during the tight condition was achieved by a higher breathing frequency (57 ± 6 vs. 52 ± 7 breaths/min; p < 0.05), despite tidal volume being significantly lower in the tight condition compared to the loose condition (1.97 ± 0.20 vs. 2.05 ± 0.23 L; p < 0.05). During steady-state submaximal running, O2 increased 1.3 ± 1.1% (range: -0.3 to 3.2%, p < 0.05) in the tight condition compared to the loose condition. Conclusions Respiratory function may become compromised by the pressure exerted by the underband of a sports bra when women self-select their bra size. In the current study, loosening the underband pressure resulted in a decreased work of breathing, changed the ventilatory breathing pattern to deeper, less frequent breaths, and decreased submaximal oxygen uptake (improved running economy). Our findings suggest sports bra underbands can impair breathing mechanics during exercise and influence whole-body metabolic rate.

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Section: Discussionsupporting

confidence: 66%

Sports Bra Restriction on Respiratory Mechanics during Exercise

KIPP,

LEAHY,

SHEEL

2024

Medicine &Amp; Science in Sports &Amp; Exercise

Self Cite

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“…In the present study in which V E at matched oxygen demand and walking speed was ~ 55–95 L min −1 in the hypoxic condition, V T was either similar or increased relative to U and LN, which again suggests that an increased power of breathing may have been required to achieve this higher V E . Importantly, this potential elevation in ventilatory work would likely hasten the development of respiratory muscle fatigue and the attendant metaboreflex (St Croix et al 2000 ; Derchak et al 2002 ), particularly in hypoxia where diaphragm fatiguability is increased (Babcock et al 1995 ; Reinhard et al 2023 ). Given this, more research is needed to assess how hypoxia, ventilatory demand, and breathing mechanics may interact to influence respiratory fatigue and blood flow responses.…”

Section: Discussionmentioning

confidence: 99%

Load carriage physiology in normoxia and hypoxia

Baur,

Buchanan

et al. 2023

Eur J Appl Physiol

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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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“…В міофібрилах і капілярах діафрагми на тлі хронічної гіпоксії, яку створювали у тварин шляхом накладання вікрилової лігатури навколо відповідної частини трахеї на 21 день, спостерігали розвиток суттєвих ультраструктурних зміни в м'язових волокнах. Подібні результати були виявлені у роботах ряду дослідників [15][16][17]. У тварин обох дослідних груп з гострою і хронічною гіпоксією загальноморфологічна організація діафрагми була гістологічно не зміненою.…”

Section: обговорення результатів дослідженняunclassified

Development of Ultrastructural Changes in Diaphragm Muscle Fibers During Partial Tracheal Stenosis in Young Sexually Immature Rats

Molochek,

Savosko,

Makarenko

2024

Act. Probl. of the Modern Med.

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Introduction. The study of congenital pathology of the respiratory tract in children is of great importance for theoretical and clinical pediatric otolaryngology. Currently, in the scientific literature there are single works concerning the study of the pathogenesis and clinic of laryngomalacia. First of all, this concerns the effect of acute and chronic hypoxia on the muscles of the respiratory system, in particular, the diaphragm. The aim of thіs work is to reveal the effect of hypoxia on the development of pronounced structural and functional changes in the diaphragm muscles of sexually immature animals when modeling partial tracheal occlusion. Materials and methods. Surgical partial occlusion of the trachea was performed on in sexually immature Wistar rats; we applied electron microscopy, morphometric and statistical research methods. Results. The obtained data demonstrated that the muscle fibers of the diaphragm are characterized by significant structural, functional and metabolic resistance to the development of acute or chronic hypoxia due to limited lung ventilation in rats. The density of muscle fibers did not change in any of the used terms of the experiment (7 and 21 days). On the 7th day of hypoxic exposure, a change in the state of the matrix of mitochondria of muscle fibers was observed, which was accompanied by partial ultrastructural rearrangements of the organization of these organelles. At the same time, no significant changes were observed during histological studies. Electrongrams demonstrated the ultrastructural damages were mainly limited to focal reduction of myofibrils and an increase in the mitochondria's diameter and found as especially pronounced on day 21 (a state of chronic hypoxia) on the muscular component of the respiratory system in rats. These changes are accompanied by the development of dystrophic disorders in the diaphragm myofibrils. On day 21 changes in the transendothelial transport of substance molecules were also detected. This was based on establishing the fact of a significant reduction in the number of pinocytosis vesicles in the cytoplasm of endothelial cells of diaphragm hemocapillaries in animals with partial tracheal occlusion. Disruption of the structural organization of actomyosin complexes was revealed in muscle fibers due to pathological changes in the mitochondria of myofibrils. It should be noted the development of destruction or complete loss of an important ultrastructural component of muscle fibers, Z-lines. These changes were completely absent on the 7th day following the influence of partial tracheal occlusion and the development of acute hypoxia. Moreover, on day 21, partial lysis of a significant amount of myofilaments of muscle fibers was observed. In addition, the development of the process of fiber swelling was detected against the background of which the above-mentioned ultrastructural destruction of the muscular component in the diaphragm was observed. These changes indicate the need for earlier treatment of laryngomalacia in children. The delay in surgical intervention leads to the development of severe or irreversible structural changes not only in the respiratory organs, but also in their muscular system. Conclusion. The muscular elements of the diaphragm have the pronounced and significant resistance to the state of hypoxia under conditions of limited ventilation of the respiratory tract. Ultrastructural and morphometric data, found on the 21st day after the modeling of partial tracheal stenosis, are not only of a compensatory and adaptive in nature, but also signs of pronounced disorders in the muscle fibers of the central part of the diaphragm in test animals.

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Effects of hypoxia on exercise‐induced diaphragm fatigue in healthy males and females

Cited by 4 publications

References 39 publications

Sports Bra Restriction on Respiratory Mechanics during Exercise

Sports Bra Restriction on Respiratory Mechanics during Exercise

Load carriage physiology in normoxia and hypoxia

Development of Ultrastructural Changes in Diaphragm Muscle Fibers During Partial Tracheal Stenosis in Young Sexually Immature Rats

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