Electrical activity of the diaphragm during progressive cycling exercise in endurance-trained men

Mathias Krogh Poulsen, Lars Pilegaard Thomsen, Nicolai Lees Mifsud, Niels-Peter Brøchner Nielsen, René Melvad Jørgensen, Søren Kjærgaard, Dan Stieper Karbing

Research output: Contribution to journalJournal articleResearchpeer-review


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). VO 2, VCO 2, VE, 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.

Original languageEnglish
JournalRespiratory Physiology & Neurobiology
Pages (from-to)77-83
Publication statusPublished - 1. Jan 2015
Externally publishedYes


  • Electromyography
  • Bicycling
  • Diaphragm/physiology
  • Exercise/physiology
  • Muscle Fatigue
  • Physical Endurance/physiology
  • Respiratory Physiological Phenomena
  • Respiratory
  • Progressive
  • Exercise
  • Drive
  • Diaphragm
  • Reliability

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