Blood pressure measures the force blood exerts against the walls of the arteries and is a fundamental indicator of cardiovascular wellness. The reading, expressed as two numbers separated by a slash, shows how effectively the heart and blood vessels circulate blood throughout the body. Understanding this measurement is important for assessing long-term health risks. This analysis will interpret the specific reading of 118/57 by breaking down its components and comparing it to official health standards.
What Systolic and Diastolic Numbers Mean
A blood pressure reading is composed of two distinct measurements, each reflecting a different phase of the heart’s cycle. The top number, 118 in this case, is the systolic pressure, which measures the pressure in the arteries when the heart muscle contracts and pushes blood out. This phase, known as systole, represents the maximum force exerted on the arterial walls during the heartbeat. A healthy systolic reading indicates the heart is pumping with appropriate force and the arteries can manage that pressure.
The bottom number, 57, is the diastolic pressure, which measures the pressure in the arteries while the heart is at rest between beats. This period of relaxation, called diastole, is when the heart chambers refill with blood. Diastolic pressure is important because it shows the minimum pressure maintained in the vessels, allowing the coronary arteries to receive oxygenated blood. Both systolic and diastolic values are measured in millimeters of mercury (mm Hg).
Standard Blood Pressure Categories
Major health organizations classify blood pressure readings into specific categories to guide health management. The most favorable category is Normal, defined as a systolic pressure below 120 mm Hg and a diastolic pressure below 80 mm Hg. Maintaining readings within this range signifies a low risk for cardiovascular complications.
The next classification is Elevated, where the systolic pressure is between 120 and 129 mm Hg, but the diastolic pressure remains below 80 mm Hg. This category is a warning sign that could progress to high blood pressure without lifestyle modifications. Hypertension, or high blood pressure, is divided into two stages.
Stage 1 Hypertension begins when the systolic pressure is between 130 and 139 mm Hg or the diastolic pressure is between 80 and 89 mm Hg. Stage 2 Hypertension is diagnosed when the systolic pressure reaches 140 mm Hg or higher, or the diastolic pressure is 90 mm Hg or higher. These cutoffs provide a standardized framework for medical professionals to assess risk and recommend treatment plans, which often involve lifestyle adjustments and sometimes medication.
How 118/57 is Classified
Analyzing the reading of 118/57 against established standards shows a generally excellent result, though one component warrants a closer look. The systolic pressure of 118 mm Hg falls within the Normal category, indicating the force exerted by the heart during contraction is well-regulated.
The diastolic pressure of 57 mm Hg is also below the 80 mm Hg limit for Normal blood pressure. A diastolic reading below 60 mm Hg is considered on the lower end of the spectrum, sometimes referred to as isolated diastolic hypotension when the systolic number is normal. While 57 is not clinically defined as hypotension (generally below 90/60 mm Hg), it approaches a range that can be concerning for some individuals.
The concern with a low diastolic number is that it can reduce blood flow and oxygen supply to the heart muscle, which receives blood primarily during the resting phase. Consistently low diastolic pressure, especially below 60 mm Hg, has been associated with an increased risk of cardiovascular damage and heart failure, particularly in older adults.
For a healthy, non-symptomatic person, 118/57 is usually considered highly favorable and beneficial. Monitoring for symptoms associated with low pressure, such as dizziness or fatigue, is important. If no symptoms are present, the overall classification is Normal, but the slightly low diastolic number warrants consistent attention during future checkups.
Why Blood Pressure Readings Fluctuate
A single blood pressure reading only captures a moment in time, as the measurement naturally changes many times throughout the day. These fluctuations are predictable responses to internal and external stimuli and do not necessarily indicate a health problem. Emotional states, such as stress or anxiety, can cause a temporary surge due to the release of hormones like adrenaline.
Physical activity is another common cause of temporary shifts, as blood pressure rises during exercise and drops afterward. Simple daily habits also influence the reading; consuming caffeine or nicotine can lead to a short-term spike by stimulating the nervous system. Blood pressure naturally follows a circadian rhythm, often being lowest during sleep and rising in the early morning.
To obtain the most accurate measurement, it is important to sit quietly for at least five minutes before the reading. The arm should be supported at heart level, the feet flat on the floor, and talking should be avoided during the measurement. Understanding these variables helps ensure that a single reading is not misinterpreted.