What is hypertension (high blood pressure)?.
Blood pressure is the force exerted by the blood against the walls of blood vessels, and the magnitude of this force depends on the cardiac output and the resistance of the blood vessels.
The blood flowing inside vessels exerts a force against the walls - this is blood pressure.
More information on the biology and physics of normal blood pressure is available, along with details of how blood pressure is measured, what normal measurements look like, and how they change with age and exercise. Hypertension is defined as having a blood pressure higher than 140 over 90 mmHg, with a consensus across medical guidelines.
This means the systolic reading (the pressure as the heart pumps blood around the body) is over 140 mmHg (millimeters of mercury) and/or the diastolic reading (as the heart relaxes and refills with blood) is over 90 mmHg.
This threshold has been set to define hypertension for clinical convenience as patients experience benefits once they bring their blood pressure below this level.
However, medical experts consider high blood pressure as having a continuous relationship to cardiovascular health.1,6 They believe that, to a point, the lower the blood pressure the better (down to levels of 115-110 mmHg systolic, and 75-70 mmHg diastolic)
This view has led the American Heart Association (AHA), for example, to define the following ranges of blood pressure (in mmHg):