Exercise as it relates to Disease/Arrhythmia in Athletes
 An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast (tachycardia), too slow (bradycardia), or with an irregular rhythm (fibrillation).  It is believed that regular endurance athletes are inducing changes in their right ventricle, almost like a form of ventricular dysplasia (scar tissue on the heart). This may eventually lead to ventricular arrhythmia and sudden death. Furthermore, for individuals who already have underlying arrhythmia or other similar heart issues, it appears that with endurance exercise the risk is heightened even further.  Sinus bradycardia and AV block can frequently be observed in athletes, but they do not require attention as long as they are asymptomatic or do not produce pauses exceeding 4 seconds.
At the moment there is no conclusive study that can directly link intense exercise as a cause of arrhythmia, but there is enough cases to warrant concern. Particularly in individuals who have a family history of premature cardiovascular disease, it is recommended that they undergo ECG screening prior to undertaking physical activity.  Medical therapy includes beta blockers or antiarrhythmics, including sotalol, amiodarone, or others. Patients at high risk of sudden death may benefit from the protection of an implanted defibrillator .
==Treatment goals==  •Prevent blood clots from forming to reduce stroke risk •Control your heart rate within a relatively normal range •Restore a normal heart rhythm, if possible •Treat heart disease/condition that may be causing arrhythmia •Reduce other risk factors for heart disease and stroke
summary box 1: common ECG patterns in junior elite athletes
1.Sinus bradycardia (heart rate < 60 beats/min) and sinus arrhythmia are common (80% and 52% respectively). 2.First degree atrioventricular block is present in 5% but higher degrees of atrioventricular block are rare. 3.Partial RBBB is present in almost one third of athletes. 4.Isolated Sokolow voltage criterion for LVH is present in almost half of all athletes. 5.ST segment elevation and tall T waves are present in 45% and 22% respectively. 6.Voltage criteria for left and right atrial enlargement are present in 14 and 16% respectively. 7.ECG changes in junior elite athletes are not dissimilar to those in senior athletes.
Some recommended readings that help support this article http://bjsm.bmj.com/content/33/5/319.full.pdf+html
1. What Is an Arrhythmia? - NHLBI, NIH. 2013. What Is an Arrhythmia? - NHLBI, NIH. [ONLINE] Available at: http://www.nhlbi.nih.gov/health/health-topics/topics/arr/. [Accessed 23 October 2013].
2. Endurance athletes: exploring the limits andbeyond . 2013. Endurance athletes: exploring the limits andbeyond . [ONLINE] Available at: http://eurheartj.oxfordjournals.org/content/24/16/1469.. [Accessed 23 October 2013].
3. Stanford Cardiovascular Health - Stanford Hospital & Clinics - Stanford Medicine. 2013. Stanford Cardiovascular Health - Stanford Hospital & Clinics - Stanford Medicine. [ONLINE] Available at: http://stanfordhospital.org/cardiovascularhealth/. [Accessed 23 October 2013].
4. Electrocardiographic changes in 1000 highly trained junior elite athletes. . 2013. Electrocardiographic changes in 1000 highly trained junior elite athletes. . [ONLINE] Available at: http://bjsm.bmj.com/content/33/5/319.full.pdf+html. [Accessed 23 October 2013].Prevention & Treatment of Arrhythmia. 2013. 5. Prevention & Treatment of Arrhythmia. [ONLINE] Available at: http://www.heart.org/HEARTORG/Conditions/Arrhythmia/PreventionTreatmentofArrhythmia/Prevention-Treatment-of-Arrhythmia_UCM_002026_Article.jsp. [Accessed 23 October 2013].