CrossTalk opposing view: Bradycardia in the trained athlete is attributable to a downregulation of a pacemaker channel in the sinus node

It is well known that athletes have a low resting heart rate (bradycardia). The bradycardia can be moderate to severe: reports of heart rates of 40–60 beats min−1 in athletes are common (Boyett et al. 2013), and Jensen-Urstad et al. (1997) reported heart rates of 500 marathons held annually worldwide. This is expected to lead to a rise in the number of athletes with heart rhythm problems and a proper understanding of the underlying mechanisms will be central to tackling these issues. Readers are invited to give their views on this and the accompanying CrossTalk articles in this issue by submitting a brief (250 word) comment. Comments may be submitted up to 6 weeks after publication of the article, at which point the discussion will close and the CrossTalk authors will be invited to submit a ‘Last Word’. Please email your comment to jphysiol@physoc.org. Alicia D'Souza is a postdoctoral research fellow at the University of Manchester following a PhD in cardiac physiology. She is also the recipient of the 2014–2015 International Society for Heart Research/Servier Research Fellowship. Dr D'Souza's current research examines the regulation of the cardiac conduction system in health and disease with special emphasis on the effect of exercise training on arrhythmogenesis. Sanjay Sharma is a cardiologist. He qualified in medicine in 1989 from Leeds University. He is currently Professor of Inherited Cardiac Diseases in Sports Cardiology at St George's Hospital, London. He specialises in sports cardiology, in particular pre-participation screening in athletes and the condition known as athlete's heart. Mark Boyett studied cardiac electrophysiology at University College London under the supervision of Brian Jewell and in 1977 was awarded his PhD. After a year as a Royal Society Overseas Fellow at the University of Berne, he moved to the University of Leeds. In 1982 he worked for the first time with Itsuo Kodama who introduced him to the wonders of the sinus node. Mark remained at Leeds for 26 years. In 2005 he moved to the University of Manchester as Professor of Cardiac Electrophysiology. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. None declared.