ELECTROCARDIOGRAPHIC ALTERATIONS ASSOCIATED WITH THE HEARTS OF ATHLETES

Physical conditioning induces numerous cardiovascular adaptations, inc luding vagotonia and increased cardiac volume and mass. These adaptati ons characterise the 'athletic heart' and account for most of the norm al variants in the athlete's electrocardiogram. Common alterations ass ociated with vagotonia include sinus bradycardia, sinus arrhythmia, ju nctional escape beats, first degree atrioventricular block and second degree (Mobitz type I) atrioventricular block. Common electrocardiogra phic variants associated with increased cardiac mass and volume includ e increased voltage, prominent U waves, intraventricular conduction de lays, early repolarisation and increased QT intervals. It is sometimes difficult to differentiate the healthy athlete with an athletic heart from the athletic patient with a diseased heart. Thus, further evalua tion may be warranted, especially when the athlete also presents with hypertension and/or abnormalities of the cardiovascular physical exami nation.