heart rate

Heart rate is simply how many times the heart beats in a minute — the speed of the pump. Like the revolutions of an engine, it rises when the body demands more (climbing stairs, fear, fever) and falls when at rest or asleep.

In a typical resting adult the heart beats about 60 to 100 times per minute. Trained athletes often sit lower, sometimes in the 40s, because their hearts pump more with each beat. Rates persistently above 100 at rest are called tachycardia and below 60 bradycardia, though neither is automatically abnormal — context matters enormously.

Heart rate is controlled moment to moment by the autonomic nervous system: a sympathetic push speeds it up, a parasympathetic (vagal) brake slows it down. It can be counted at the pulse, listened to with a stethoscope, or measured precisely on an electrocardiogram, and together with blood pressure and breathing it is one of the core vital signs.