An extra heart beat. The normal rhythm of the heart is regulated by signals from the pacemaker region. However, sometimes a signal can come from outside the pacemaker, causing an ectopic beat. Although sometimes worrying and uncomfortable, ectopic beats are usually harmless, but if they occur during exercise, and increase with intensity of exercise, or if they combine with other abnormalities they may be linked to more serious heart conditions.
Subjects: Sports and Exercise Medicine.