Research article summary (published 29 Apr 1991):

Inspiratory muscle relaxation rate after voluntary maximal isocapnic ventilation in humans.

Full Abstract

We have investigated whether the capacity of the inspiratory muscles to generate pressure and flow during a ventilatory load is related to changes in inspiratory muscle relaxation rate. Five highly motivated normal subjects performed voluntary maximal isocapnic ventilation (MIV) for 2 min. Minute ventilation and esophageal, gastric, and transdiaphragmatic pressures were measured breath by breath. We observed that ventilation, peak inspiratory and expiratory pressures, and inspiratory flow rate declined from the start of the run to reach a plateau at 60 s that was sustained for the remainder of the exercise. In a subsequent series of studies, MIV was performed for variable durations between 15 and 120 s. The normalized maximum relaxation rate of unoccluded inspiratory sniffs (sniff MRR, %pressure loss/10 ms) was determined immediately on stopping MIV. Sniff MRR slowed as the duration of MIV increased and paralleled the decline in inspiratory pressure and ventilation observed during the 2-min exercise. No further slowing in MRR occurred when ventilation became sustainable. We conclude that, during MIV, the progressive loss of ventilation and capacity to generate pressure is associated with the early onset and progression of a peripheral fatiguing process within the inspiratory muscles.

Author information

Author/s: Mulvey, D A (DA); Koulouris, N G (NG); Elliott, M W (MW); Laroche, C M (CM); Moxham, J (J); Green, M (M);

Affiliation: Respiratory Muscle Laboratory, Brompton Hospital, London, United Kingdom.

Journal and publication information

Publication Type: Journal Article

Journal: Journal of applied physiology (Bethesda, Md. : 1985) (J Appl Physiol), published in UNITED STATES. (Language: eng)

Reference: 1991-May; vol 70 (issue 5) : pp 2173-80

Dates: Created 1991/09/09; Completed 1991/09/09; Revised 2004/11/17;

PMID: 1907603, status: MEDLINE (last retrieved date: 2/18/2009)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MeSH Headings (categories) shown below.

Adult Carbon Dioxide Electric Stimulation Fatigue - physiopathology Female Humans

Male Muscle Relaxation - physiology Phrenic Nerve - physiology Pressure Respiratory Mechanics - physiology Respiratory Muscles - physiology

Note: Bold headings indicate primary MeSH headings or qualifiers.

Associated Chemicals: Carbon Dioxide (124-38-9)

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