A heartbeat which momentarily loses its rhythm. The heart may miss a beat which is then followed by a heavy jolt. It is not a cause for concern as long as a person with ectopic beats has an otherwise normal heart, and as long as the ectopics occur during rest. If they occur during exercise and increase in frequency with the intensity of exercise, or if the ectopics combine with other abnormalities, the sufferer should seek medical advice.

Well-trained athletes have a relatively high incidence of abnormal heart rhythms but, in the absence of other symptoms, these variations are normal and do not indicate heart disease. Ectopics can be caused by drugs such as caffeine.

Food and Fitness: A Dictionary of Diet and Exercise. Copyright © 1997, 2003 by Oxford University Press. All rights reserved.