In normal resting conditions, the activity of the heart is generally not perceived by the individual. However, during or immediately after intense physical activity or emotional stress, it may be quite normal to become aware of one's own heartbeat for brief periods; these sensations are regarded as physiological palpitations, in that they represent the normal or expected response to a certain challenge or activity leading to an increase in the frequency and strength of the contraction of the heart. Outside of such situations, instead, palpitations are perceived as abnormal