Risk of Arrhythmias in 52,755 Long-Distance Cross-Country Skiers: A Cohort Study

Study Questions:

Is there an association between the number of completed races and finishing time, and the risk of arrhythmias among participants of Vasaloppet, a 90 km cross-country skiing event?


All participants without known cardiovascular disease who completed Vasaloppet, from 1989 to 1998, were followed through national registries until December 2005. The primary outcome was hospitalization for any arrhythmia; and secondary outcomes were atrial fibrillation/flutter (AF), bradyarrhythmias, other supraventricular tachycardias (SVTs), and ventricular tachycardia/ventricular fibrillation/cardiac arrest (VT/VF/CA).


Among 52,755 participants, 919 experienced arrhythmia during follow-up. Adjusting for age, education, and occupational status, those who completed the highest number of races during the period had higher risk of any arrhythmias (hazard ratio [HR],1.30; 95% confidence interval [CI], 1.08-1.58; for ≥5 vs. 1 completed race), AF (HR, 1.29; 95% CI, 1.04-1.61), and bradyarrhythmias (HR, 2.10; 95% CI, 1.28-3.47). Those who had the fastest relative finishing time also had higher risk of any arrhythmias (HR, 1.30; 95% CI, 1.04-1.62; for 100-160% vs. >240% of winning time), AF (HR, 1.20; 95% CI, 0.93-1.55), and bradyarrhythmias (HR, 1.85; 95% CI, 0.97-3.54). SVT or VT/VF/CA was not associated with finishing time or number of completed races.


Among male participants of a 90 km cross-country skiing event, a faster finishing time and a high number of completed races were associated with higher risk of arrhythmias. This was mainly driven by a higher incidence of AF and bradyarrhythmias. No association with SVT or VT/VF/CA was found.


Increased vagal tone associated with increased aerobic fitness has been implicated as a factor predisposing to AF. This study suggests that surrogate markers for aerobic fitness (number of endurance races completed and faster finishing times) had a direct correlation with risk of arrhythmias including AF and bradyarrhythmias. To the dedicated endurance athlete, this probably is not a reason to train less or to compete at a lower level, but it provides an interesting suggestion of increased cardiac risk (albeit not a mortal cardiac risk) as a result of high-level aerobic conditioning.

Clinical Topics: Arrhythmias and Clinical EP, Sports and Exercise Cardiology, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Athletes, Tachycardia, Supraventricular, Ventricular Fibrillation, Sports, Transcription Factors, Heart Arrest, Tachycardia, Ventricular, Bradycardia, Pregnancy, Prolonged, Hospitalization, Skiing, Atrial Flutter

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