title: Remote ischaemic preconditioning shortens QT intervals during exercise in healthy subjects.
abstract: The protective action of remote ischaemic preconditioning (RIPC) has been demonstrated in the context of surgical interventions in cardiology. Application of RIPC to sports performance has been proposed, but its effect on the electrocardiogram (ECG) during exercise remains unknown. This exploratory study aims to measure the changes in ventricular repolarization observed during exercise following RIPC in healthy subjects. In an experimental randomized crossover study, 17 subjects underwent two bouts of constant load exercise tests at 75% and 115% of gas exchange threshold (GET). Prior to exercise, they were allocated to either control or RIPC intervention with four cycles of 5 min of ischaemia followed by 5 min of reperfusion. ECG was continuously recorded during the protocol. QT and RR intervals were measured every 30 s (on an average tracing of the preceding 10 s). Although the time course of RR intervals did not differ between the two interventions (p = .56 at 75% GET and p = .74 at 115% GET), a significant shortening of QT intervals (measured from Q onset to T end) was observed during exercise (mean ± standard deviation of RIPC vs.
  
  
  METHODS
  -32 ± 19 ms at 75% GET (p < .001) and -34 ± 12 ms at 115% GET (p < .001)) as well as during recovery (-21 ± 8 ms at 75% GET (p < .001) and -16 ± 11 ms at 115% GET (p < .001)). This effect was not present at rest. These RIPC-related changes were clearly identifiable on the QT-RR loops after hysteresis reduction. RIPC therefore induces heart rate-independent shortening of QT intervals that is revealed during exercise.
authors.affiliation: a Department of Kinesiology , University of Montreal , Montreal , QC , Canada.|b Laboratory of Pathophysiology of EXercise (LPEX), Department of Kinesiology , University of Montreal , Montreal , QC , Canada.
authors.forename: Maxime
authors.initials: M
authors.lastname: Caru
authors.affiliation: a Department of Kinesiology , University of Montreal , Montreal , QC , Canada.|b Laboratory of Pathophysiology of EXercise (LPEX), Department of Kinesiology , University of Montreal , Montreal , QC , Canada.|c Centre Hospitalier de l'Université de Montréal, Research Center (CRCHUM) , Montreal , QC , Canada.
authors.forename: François
authors.initials: F
authors.lastname: Lalonde
authors.affiliation: a Department of Kinesiology , University of Montreal , Montreal , QC , Canada.|b Laboratory of Pathophysiology of EXercise (LPEX), Department of Kinesiology , University of Montreal , Montreal , QC , Canada.
authors.forename: Hugo
authors.initials: H
authors.lastname: Gravel
authors.affiliation: a Department of Kinesiology , University of Montreal , Montreal , QC , Canada.
authors.forename: Chantal
authors.initials: C
authors.lastname: Daigle
authors.affiliation: c Centre Hospitalier de l'Université de Montréal, Research Center (CRCHUM) , Montreal , QC , Canada.|d Cardiology Division , Centre Hospitalier de l'Université de Montréal (CHUM) , Montreal , QC , Canada.
authors.forename: François
authors.initials: F
authors.lastname: Tournoux
authors.affiliation: e Department of Molecular and Integrative Physiology , University of Montreal , Montreal , QC , Canada.|f Hôpital du Sacré-Coeur de Montréal , Research Center , Montreal , QC , Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Jacquemet
authors.affiliation: a Department of Kinesiology , University of Montreal , Montreal , QC , Canada.|b Laboratory of Pathophysiology of EXercise (LPEX), Department of Kinesiology , University of Montreal , Montreal , QC , Canada.|c Centre Hospitalier de l'Université de Montréal, Research Center (CRCHUM) , Montreal , QC , Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Curnier
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D019194:Ischemic Preconditioning / Q000706:statistics & numerical data*; D008297:Male; D055815:Young Adult
keywords: QT-interval; Remote ischaemic preconditioning; electrophysiology; exercise; sports medicine; ventricular repolarization