Oxygen cost of exercise hyperpnea: implications for performance

Aaron, E. A.; Seow, K. C.; Johnson, Bruce D.; Dempsey, Jerome A.

doi:10.1152/jappl.1992.72.5.1818

Cited by 321 publications

(258 citation statements)

References 17 publications

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“…To meet these ventilatory requirements the respiratory muscles require a substantial blood flow and O 2 supply. Data in highly fit subjects suggest that up to 16% of the total V O 2 max and total cardiac output is devoted to inspiratory and expiratory muscles during maximum exercise (3,40). These indirect estimates agree closely with those in running equines as measured directly with radiolabeled microspheres (75,76).…”

Section: Exercise Demands On the Respiratory Musclessupporting

confidence: 69%

Exercise-induced respiratory muscle fatigue: implications for performance

Romer

Polkey²

2008

Journal of Applied Physiology

260

212

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Romer LM, Polkey MI. Exercise-induced respiratory muscle fatigue: implications for performance. J Appl Physiol 104: 879 -888, 2008. First published December 20, 2007 doi:10.1152/japplphysiol.01157.2007.-It is commonly held that the respiratory system has ample capacity relative to the demand for maximal O 2 and CO2 transport in healthy humans exercising near sea level. However, this situation may not apply during heavy-intensity, sustained exercise where exercise may encroach on the capacity of the respiratory system. Nerve stimulation techniques have provided objective evidence that the diaphragm and abdominal muscles are susceptible to fatigue with heavy, sustained exercise. The fatigue appears to be due to elevated levels of respiratory muscle work combined with an increased competition for blood flow with limb locomotor muscles. When respiratory muscles are prefatigued using voluntary respiratory maneuvers, time to exhaustion during subsequent exercise is decreased. Partially unloading the respiratory muscles during heavy exercise using low-density gas mixtures or mechanical ventilation can prevent exercise-induced diaphragm fatigue and increase exercise time to exhaustion. Collectively, these findings suggest that respiratory muscle fatigue may be involved in limiting exercise tolerance or that other factors, including alterations in the sensation of dyspnea or mechanical load, may be important. The major consequence of respiratory muscle fatigue is an increased sympathetic vasoconstrictor outflow to working skeletal muscle through a respiratory muscle metaboreflex, thereby reducing limb blood flow and increasing the severity of exerciseinduced locomotor muscle fatigue. An increase in limb locomotor muscle fatigue may play a pivotal role in determining exercise tolerance through a direct effect on muscle force output and a feedback effect on effort perception, causing reduced motor output to the working limb muscles. respiratory muscles; exercise; diaphragm; abdominals; magnetic stimulation; metaboreflex THE PURPOSE OF THIS MINIREVIEW is to address the question of whether the respiratory demands of exercise contribute significantly toward exercise limitation, either directly through limitations of the respiratory muscle pump or indirectly through effects on limb blood flow and locomotor muscle fatigue. We describe the mechanical and metabolic costs of meeting the ventilatory requirements of exercise. We then ask whether the respiratory muscles fatigue with exercise, what factors contribute to any such fatigue, and what the implications of these factors are for exercise tolerance. Finally, we deal with the potential mechanisms by which respiratory muscle fatigue could compromise exercise tolerance and whether it is possible to overcome this potential respiratory limitation. Our review focuses on the healthy young adult exercising near sea level. However, we also consider special circumstances that determine the balance between metabolic demand and respiratory system capacity in the highly trained endurance ...

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Section: Exercise Demands On the Respiratory Musclessupporting

confidence: 69%

Exercise-induced respiratory muscle fatigue: implications for performance

Romer

Polkey²

2008

Journal of Applied Physiology

260

212

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“…1 However, mask-induced respiratory changes remain central in the explanations for impaired exercise performance during mask wear in the studies discussed above. First, an obvious difference between mask wear and non-wear is respiratory dead space.…”

Section: Discussionmentioning

confidence: 99%

Incremental exercise test performance with and without a respiratory gas collection system

Clark¹

2017

S. Afr. j. sports med

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IntroductionExercise testing with respiratory gas collection (RGC) and analysis during indirect calorimetry has long been a routine procedure in exercise physiology laboratories, enabling the simultaneous measureorIgInal research arTIcle abstract objective. Despite their widespread use in exercise testing, few data are available on the effect of wearing respiratory gas collection (RGC) systems on exercise test performance. Industrial-type mask wear is thought to impair exercise performance through increased respiratory dead space, flow resistance and/or discomfort when compared with RGC facemasks, but whether performance decrements exist for RGC facemask wear versus non-wear is unclear. The objective of this study was to evaluate the difference in incremental exercise test performance with and without a RGC system. Incremental exercise test performance with and without a respiratory gas collection system corresPonDence:James James r clark (Bsc (hons), (Ba (hons))Institute for Sport Research, Department of Biokinetics, Sport and Leisure Sciences, University of Pretoria Design. Twenty moderately active males (age 21.0 ± 1.9 years; VO2peak 55.9 ± 3.0 ml•kg -1 •min -1 ) performed two progressive treadmill tests to volitional exhaustion. In random order subjects ran with (MASK) or without (NO-MASK) a RGC facemask and flow sensor connected to a gas analyzer. Descriptive data (mean ± SD) were determined for all parameters. The Wilcoxon signed rank test for paired differences was used to assess mean differences between MASK and NO-MASK conditions.results. Exercise time to exhaustion, peak treadmill speed, peak blood lactate concentration, peak heart rate and rating of perceived exertion (RPE) were not different (p>0.05) between MASK and NO-MASK conditions.conclusions. Incremental exercise test performance is not adversely affected by RGC and analysis equipment, at least in short duration progressive treadmill exercise. Respiratory gas analysis during exercise testing for diagnostic, performance assessment or training prescription purposes would appear to be unaffected by RGC systems.

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“…In support of this concept, Aaron et al [35] observed that the oxygen cost of breathing increases to 15% of total oxygen consumption in the presence of severe expiratory airflow limitation.…”

Section: Increased Work and Oxygen Cost Of Respiratory Musclesmentioning

confidence: 93%

“…During exercise in healthy subjects, the oxygen consumption of respiratory muscles accounts for 5-10% of whole body oxygen consumption [35]. However, alterations in EELV, ventilation-perfusion ratio and airway calibre alter the work, and therefore oxygen consumption of the respiratory muscles [36].…”

Section: Increased Work and Oxygen Cost Of Respiratory Musclesmentioning

confidence: 99%