scholarly journals The Respiratory System during Intermittent-Sprint Work: Respiratory Muscle Work and the Critical Distribution of Oxygen

2020 ◽  
Author(s):  
Ramón F. Rodriguez ◽  
Robert J. Aughey ◽  
François Billaut
Keyword(s):  
Respiratory System ◽  
Work Of Breathing ◽  
Respiratory Muscles ◽  
Moderate Intensity ◽  
Healthy Individuals ◽  
Moderate Intensity Exercise ◽  
Muscle Work ◽  
Skeletal Muscle Oxygenation ◽  
New Evidence ◽  
The Relationship

In healthy individuals at rest and while performing moderate-intensity exercise, systemic blood flow is distributed to tissues relative to their metabolic oxygen demands. During sustained high-intensity exercise, competition for oxygen delivery arises between locomotor and respiratory muscles, and the heightened metabolic work of breathing, therefore, contributes to limited skeletal muscle oxygenation and contractility. Intriguingly, this does not appear to be the case for intermittent-sprint work. This chapter presents new evidence, based on inspiratory muscle mechanical loading and hypoxic gas breathing, to support that the respiratory system of healthy men is capable of accommodating the oxygen needs of both locomotor and respiratory muscles when work is interspersed with short recovery periods. Only when moderate hypoxemia is induced, substantial oxygen competition arises in favour of the respiratory muscles. These findings extend our understanding of the relationship between mechanical and metabolic limits of varied exercise modes.

O2 uptake kinetics, pyruvate dehydrogenase activity, and muscle deoxygenation in young and older adults during the transition to moderate-intensity exercise

2008 ◽  
Vol 294 (2) ◽  
pp. R577-R584 ◽  
Author(s):  
B. J. Gurd ◽  
S. J. Peters ◽  
G. J. F. Heigenhauser ◽  
P. J. LeBlanc ◽  
T. J. Doherty ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Pyruvate Dehydrogenase ◽  
Lactate Threshold ◽  
Time Course ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Similar Time ◽  
O2 Uptake Kinetics ◽  
The Relationship

The adaptation of pulmonary O2 uptake (V̇o2p) kinetics is slowed in older compared with young adults during the transition to moderate-intensity exercise. In this study, we examined the relationship between V̇o2p kinetics and mitochondrial pyruvate dehydrogenase (PDH) activity in young ( n = 7) and older ( n = 6) adults. Subjects performed cycle exercise to a work rate corresponding to ∼90% of estimated lactate threshold. Phase 2 V̇o2p kinetics were slower ( P < 0.05) in older (τ = 40 ± 17 s) compared with young (τ = 21 ± 6 s) adults. Relative phosphocreatine (PCr) breakdown was greater ( P < 0.05) at 30 s in older compared with young adults. Absolute PCr breakdown at 6 min was greater ( P < 0.05) in older compared with young adults. In young adults, PDH activity increased ( P < 0.05) from baseline to 30 s, with no further change observed at 6 min. In older adults, PDH activity during baseline exercise was similar to that seen in young adults. During the exercise transition, PDH activity did not increase ( P > 0.05) at 30 s of exercise but was elevated ( P < 0.05) after 6 min. The change in deoxyhemoglobin (HHb) was greater for a given V̇o2p in older adults, and there was a similar time course of HHb accompanying the slower V̇o2p kinetics in the older adults, suggesting a slower adaptation of bulk O2 delivery in older adults. In conclusion, the slower adaptation of V̇o2p in older adults is likely a result of both an increased metabolic inertia and lower O2 availability.

Variations in air viscosity due to changes in water vapor pressure for isothermal conditions at temperatures below 40 °C

1970 ◽  
Vol 48 (1) ◽  
pp. 50-53 ◽  
Author(s):  
P. D. Roy ◽  
W. T. Josenhans ◽  
C. H. Miller
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Work Of Breathing ◽  
Water Vapor Pressure ◽  
Respiratory Muscles ◽  
Work Load ◽  
Reynolds Numbers ◽  
Pressure Drops ◽  
Isothermal Test ◽  
The Relationship

The viscosities of moist and dry air were measured at four temperatures to determine variations due to changes in water vapor content under isothermal test conditions. Paired measurements (240) of volumetric rates of air flow and pressure drops along a tube were made. Corresponding coefficients of viscosity were calculated from the Hagen–Poiseuille equation, laminar flow being assured by limiting maximal Reynolds numbers. The relationship between viscosity (η) and water vapor pressure [Formula: see text] was found to be approximately linear. The increase in the work load of the respiratory muscles due to an increase in air humidity, and hence viscosity, from purely physical considerations, appears to be very small compared with the total work of breathing.

scholarly journals Eicosanoid Production following One Bout of Exercise in Middle-Aged African American Pre- and Stage 1 Hypertensives

2011 ◽  
Vol 2011 ◽  
pp. 1-7
Author(s):  
Sheara Williamson ◽  
Deepti Varma ◽  
Michael Brown ◽  
Susan Jansen
Keyword(s):  
African American ◽  
Aerobic Capacity ◽  
High Performance ◽  
Urinary Metabolites ◽  
Moderate Intensity ◽  
Middle Aged ◽  
Moderate Intensity Exercise ◽  
Exercise Induced ◽  
The Relationship ◽  
Eicosanoid Formation

Endothelial dysfunction and a sedentary lifestyle may be involved in the development of hypertension which is proliferative among middle-aged African Americans (AA). Signaling molecules derived from the oxidation of 20-carbon fatty acid molecules known as eicosanoids influence vascular tone. The relationship between aerobic fitness and eicosanoid formation following exercise in middle-aged African American hypertensives is unknown.Purpose. To determine the relationship between aerobic capacity and eicosanoid formation after a bout of moderate-intensity exercise in middle-aged AA hypertensives.Methods. Ten sedentary hypertensive AA underwent 50 min of aerobic exercise at 65% VO2max. Urine was collected for 24 hr on two occasions, prior to testing and immediately following the bout of exercise. Urinary metabolites of prostacyclin (6-keto PGF1α) and thromboxane (11-dTXB2) were measured during the day and night periods by high-performance liquid chromatography (HPLC).Results. 6-keto PGF1αlevels significantly increased () following the bout of exercise compared to the control day. There was a significant relationship (, ) between 6-keto PGF1αlevels and VO2max during the exercise day.Conclusion. Based on this preliminary study, there appears to be a relationship between aerobic capacity and exercise-induced 6-keto PGF1αproduction in middle-aged hypertensive AAs. AAs with lower VO2max had lower 6-keto PGF1αformation.

Pulmonary function

2017 ◽  
Author(s):  
Alison M McManus ◽  
Neil Armstrong
Keyword(s):  
Pulmonary Function ◽  
Ventilatory Response ◽  
Work Of Breathing ◽  
Pulmonary Ventilation ◽  
Moderate Intensity ◽  
Energetic Cost ◽  
Metabolic Demand ◽  
Moderate Intensity Exercise ◽  
Ventilatory Control ◽  
Considerable Research

The principles of pulmonary ventilation are the same for children and adults. Ventilation adjusts to alterations in metabolic demand in the child; but for a given exercise intensity there is a greater ventilation when expressed relative to body mass and a higher energetic cost of breathing in the child compared to the adult. Limited evidence suggests child-adult differences may be a result of immature chemoreception, a greater drive to breathe, differences in airway dimensions, and the mechanical work of breathing. There are few studies investigating the dynamic ventilatory response to moderate intensity exercise and none to heavy or very heavy intensity exercise in the child. Little attention has been devoted to the developmental pattern of ventilatory control, although there is evidence of altered chemoreceptive modulation of breathing in the child. Considerable research will be necessary before we have a full appreciation of pulmonary function during exercise in the child.

scholarly journals Respiratory muscle function in the newborn: a narrative review

2021 ◽  
Author(s):  
Theodore Dassios ◽  
Aggeliki Vervenioti ◽  
Gabriel Dimitriou
Keyword(s):  
Congenital Anomalies ◽  
Muscle Function ◽  
Respiratory Muscle ◽  
Work Of Breathing ◽  
Respiratory Muscles ◽  
Current Evidence ◽  
Muscle Fibres ◽  
List Type ◽  
Respiratory Muscle Function ◽  
Neurally Adjusted Ventilator Assist

Abstract Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure–time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. Impact Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.

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