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Grippo A, Carrai R, Chiti L, Bruni GI, Scano G, Duranti R. Effect of limb muscle fatigue on perception of respiratory effort in healthy subjects. J Appl Physiol (1985) 2010; 109:367-76. [DOI: 10.1152/japplphysiol.00608.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The role of nonrespiratory peripheral afferents in dyspnea perception has not been fully elucidated yet. Our hypothesis is that fatigue-induced activation of limb muscle metaboreceptors served by group IV fine afferent fibers may impact on respiratory effort perception. We studied 12 healthy subjects breathing against progressive inspiratory resistive loads (10, 18, 30, 40, and 90 cmH2O·l−1·s) before and after inducing low-frequency fatigue of quadriceps muscle by repeating sustained contractions at ≥80% of maximal voluntary contraction. Subjects also underwent a sham protocol while performing two loaded breathing runs without muscle fatigue in between. During the loaded breathing, while subjects mimicked the quiet breathing pattern using a visual feedback, ventilation, tidal volume, respiratory frequency, pleural pressure swings, arterial oxygen saturation, end-tidal partial pressure of CO2, and dyspnea by a Borg scale were recorded. Compared with prefatigue, limb muscle fatigue resulted in a higher increase in respiratory effort perception for any given ventilation, tidal volume, respiratory frequency, pleural pressure swings, end-tidal partial pressure of CO2, and arterial oxygen saturation. No difference between the two runs was observed with the sham protocol. The present data support the hypothesis that fatigue of limb muscles increases respiratory effort perception associated with loaded breathing, likely by the activation of limb muscle metaboreceptors.
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Affiliation(s)
- Antonello Grippo
- Neurological and Psychiatric Sciences, University of Florence, and
- Departments of 3Neurology and
| | - Riccardo Carrai
- Neurological and Psychiatric Sciences, University of Florence, and
- Respiratory Rehabilitation, Fondazione Don Gnocchi IRCCS, Florence, Italy
| | | | | | - Giorgio Scano
- Departments of 1Internal Medicine and
- Respiratory Rehabilitation, Fondazione Don Gnocchi IRCCS, Florence, Italy
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Dyspnea. Mechanisms, assessment, and management: a consensus statement. American Thoracic Society. Am J Respir Crit Care Med 1999; 159:321-40. [PMID: 9872857 DOI: 10.1164/ajrccm.159.1.ats898] [Citation(s) in RCA: 754] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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