Blood pressure represents the force exerted by circulating blood against the inner walls of your arteries. This force is primarily generated by your heart as it pumps blood throughout the circulatory system. Understanding your blood pressure numbers is important because they offer insights into your cardiovascular well-being, influencing the delivery of oxygen and nutrients to all your organs and tissues.
What Do the Numbers Mean?
Blood pressure readings consist of two distinct numbers, typically presented as a fraction, such as 120/80 mmHg. The top number is the systolic pressure, which reflects the pressure in your arteries when your heart contracts and pushes blood out. This phase, called systole, is when the pressure on your arterial walls is highest.
The bottom number represents the diastolic pressure, which is the pressure in your arteries when your heart rests and refills with blood between beats. During this relaxation phase, known as diastole, the blood pressure within the vessels is at its lowest.
Decoding Blood Pressure Categories
Healthcare organizations define specific blood pressure ranges to categorize a person’s status. Normal blood pressure is considered a systolic reading less than 120 mmHg and a diastolic reading less than 80 mmHg. Maintaining these levels indicates healthy blood flow and heart function.
Elevated blood pressure is defined by a systolic pressure between 120 and 129 mmHg and a diastolic pressure less than 80 mmHg. This category warns of increased risk for developing high blood pressure. Lifestyle adjustments are often recommended to prevent progression.
Hypertension Stage 1 is diagnosed when systolic pressure is between 130 and 139 mmHg or diastolic pressure is between 80 and 89 mmHg. At this stage, cardiovascular complication risk doubles compared to normal. Medical guidance, including potential lifestyle changes, often begins here.
Hypertension Stage 2 applies to readings where systolic pressure is 140 mmHg or higher, or diastolic pressure is 90 mmHg or higher. This indicates significant high blood pressure, often requiring both lifestyle modifications and medication to manage.
A hypertensive crisis is a severe condition where systolic pressure exceeds 180 mmHg and/or diastolic pressure exceeds 120 mmHg. This demands immediate medical attention, especially with symptoms of organ damage. Low blood pressure (hypotension) generally falls below 90/60 mmHg and can cause dizziness or fainting.
Factors That Influence Your Readings
Numerous factors can influence blood pressure readings, both temporarily and over the long term. Short-term influences include physical activity, which can cause systolic pressure to increase by 10 to 20 mmHg. Consuming alcohol, caffeine, or tobacco can also cause temporary spikes; avoid these for at least 30 minutes before a measurement.
Emotional states like stress or anxiety can elevate blood pressure. Even talking during a measurement can increase systolic pressure by 10 to 15 mmHg. Proper posture, with a supported back and uncrossed legs, also impacts accuracy.
Long-term influences on blood pressure include dietary habits, exercise levels, and overall body weight. Age and genetics also play a role; systolic blood pressure often rises with age due to stiffening arteries. Medications and health conditions can also affect readings. White coat syndrome, where readings are higher in a clinical setting due to anxiety, is another common influence.
How Blood Pressure is Measured
Blood pressure is measured using an inflatable cuff and a pressure gauge. In a clinical setting, a healthcare provider wraps the cuff around the upper arm, just above the elbow. The cuff is then inflated, temporarily compressing the brachial artery and blocking blood flow.
As the cuff slowly deflates, the healthcare provider uses a stethoscope to listen for blood flow, noting when the first sound is heard (systolic) and when sounds disappear (diastolic). Automated devices perform this process electronically, displaying the readings digitally.
At-home monitoring is widely used to track readings outside a doctor’s office. For accurate home readings, use an automated upper-arm cuff on a bare arm, rest for five minutes before measuring, and avoid talking. Taking multiple readings, ideally two in the morning and two in the evening for a week, provides a comprehensive picture of typical blood pressure.