Article Text

Effects of training adaption in endurance athletes with atrial fibrillation: protocol for a multicentre randomised controlled trial
  1. Turid Apelland1,
  2. Kristel Janssens2,
  3. Jan Pål Loennechen3,4,
  4. Guido Claessen5,6,7,
  5. Eivind Sørensen1,8,
  6. Amy Mitchell2,
  7. Andreas Berg Sellevold3,4,
  8. Steve Enger1,
  9. Sophia Onarheim1,
  10. Jon Magne Letnes3,4,
  11. Hielko Miljoen9,10,
  12. Arnljot Tveit1,11,
  13. André La Gerche2,12,
  14. Marius Myrstad1,8
  15. on behalf of The NEXAF investigators
  1. 1Department of Medical Research, Bærum Hospital Vestre Viken Trust, Gjettum, Norway
  2. 2Baker Heart and Diabetes Institute, Sports Cardiology Laboratory, Melbourne, Victoria, Australia
  3. 3Clinic of Cardiology, St. Olav’s Hospital, Trondheim University Hospital, Trondheim, Norway
  4. 4Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
  5. 5UHasselt, Faculty of Medicine and Life Sciences, BIOMED-REVAL-Rehabilitation Research Centre, Hasselt University, Diepenbeek, Belgium
  6. 6Hartcentrum Hasselt, Jessa Hospital Hasselt, Belgium
  7. 7Department of Cardiovascular Diseases, KU Leuven, Leuven, Belgium
  8. 8Department of Internal Medicine, Bærum Hospital Vestre Viken Trust, Gjettum, Norway
  9. 9Department of Cardiology, Antwerp University Hospital, Antwerp, Belgium
  10. 10Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
  11. 11Institute of Clinical Medicine, University of Oslo, Oslo, Norway
  12. 12Department of Medicine, St Vincent's Hospital, University of Melbourne, Fitzroy, Victoria, Australia
  1. Correspondence to Dr Turid Apelland; turid.apelland{at}


Endurance athletes have a high prevalence of atrial fibrillation (AF), probably caused by exercise-induced cardiac remodelling. Athletes diagnosed with AF are often advised to reduce the intensity and amount of training but the efficacy of this intervention has not been investigated in endurance athletes with AF. Effects of detraining in endurance athletes with atrial fibrillation is a two-arm international multicentre randomised (1:1) controlled trial on the effects of a period of training adaption on AF burden in endurance athletes with paroxysmal AF.

One-hundred-and-twenty endurance athletes diagnosed with paroxysmal AF are randomised to a 16-week period of intervention (training adaption) or a control group. We define training adaption as training with a heart rate (HR) not exceeding 75% of the individual maximum HR (HRmax), and total duration of weekly training not exceeding 80% of the self-reported average before the study. The control group is instructed to uphold training intensity including sessions with HR ≥85% of HRmax. AF burden is monitored with insertable cardiac monitors, and training intensity with HR chest-straps and connected sports watches. The primary endpoint, AF burden, will be calculated as the cumulative duration of all AF episodes lasting ≥30sec divided by total duration of monitoring. Secondary endpoints include number of AF episodes, adherence to training adaption, exercise capacity, AF symptoms and health-related quality of life, echocardiographic signs of cardiac remodelling and risk of cardiac arrhythmias related to upholding training intensity.

Trial registration number NCT04991337.

Study protocol version 4.7 (Date 9 March 2023).

  • Exercise
  • Sports medicine
  • Athlete
  • Endurance
  • Cardiology

Data availability statement

No data are available.

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Data availability statement

No data are available.

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  • Contributors All authors have contributed to the design of the study. TA and MM drafted the manuscript. All authors read and contributed to the manuscript, gave approval and agreed to be accountable for all aspects of the work.

  • Funding This study is funded by The Norwegian Health Association and Vestre Viken Hospital Trust, Norway.

  • Disclaimer The funders did not have any role in the study design and will not have any role in the collection, management, analysis and interpretation of data or in the writing of the report or decision to submit the report for publication.

  • Competing interests None declared.

  • Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.