title: Electrical activity of the diaphragm during progressive cycling exercise in endurance-trained men.
abstract: The study aimed to investigate diaphragm respiratory drive modulation through electrical activity of the diaphragm (EADi) during progressive cycling in endurance-trained men (N=7) and to test day-to-day measurement reliability. Normalized EADi increased at exercise intensities from 40% workload (WL) to 70% and 85%WL but plateaued from 70% to 85% (p<0.05). V˙O2, V˙CO2, V˙E, increased at all exercise intensities, where Vt and BF increased from 40% to 55% WL and from 70% to 85% and RER increased at 70% and 85% (p<0.05). Bland-Altman plots of normalized EADi showed bias of 0.9% and -6.4% and limits of agreement of ±36.0% and ±30.4% for absolute measurements and relative changes from 40% WL, respectively. Within-day variability appeared constant indicating that measurements within a trial are reliable. Results suggest that diaphragm respiratory drive increases at moderate exercise intensities, but plateaus at high intensities where other respiratory muscles might contribute significantly to the breathing effort, perhaps to "protect" against diaphragm fatigue.
authors.affiliation: Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark. Electronic address: mkpo@hst.aau.dk.
authors.forename: Mathias Krogh
authors.initials: MK
authors.lastname: Poulsen
authors.affiliation: Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark.
authors.forename: Lars Pilegaard
authors.initials: LP
authors.lastname: Thomsen
authors.affiliation: Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark.
authors.forename: Nicolai Lees
authors.initials: NL
authors.lastname: Mifsud
authors.affiliation: Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark.
authors.forename: Niels-Peter Brøchner
authors.initials: NP
authors.lastname: Nielsen
authors.affiliation: Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark.
authors.forename: René Melvad
authors.initials: RM
authors.lastname: Jørgensen
authors.affiliation: Department of Anesthesiology, Aalborg University Hospital, 9000 Aalborg, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Kjærgaard
authors.affiliation: Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark.
authors.forename: Dan Stieper
authors.initials: DS
authors.lastname: Karbing
mesh_terms: D000328:Adult; D001642:Bicycling; D003964:Diaphragm / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D012143:Respiratory Physiological Phenomena
keywords: Diaphragm; Drive; Exercise; Progressive; Reliability; Respiratory