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Heart rate refers to the number of times the heart contracts, or beats, in one minute. It is one of the most basic and vital signs used to evaluate the functioning of the cardiovascular system. Each beat of the heart pushes blood, carrying oxygen and nutrients, through the arteries to supply the body’s tissues and organs. By counting the beats per minute, doctors and individuals can assess how efficiently the heart is working and how well the body is being supplied with blood and oxygen.

In simple terms, heart rate is a measure of the speed of the heartbeat. It reflects the interaction of the heart’s electrical system, muscular contractions, and the body’s overall demands for oxygen. The heart rate increases when the body requires more oxygen, such as during exercise, stress, or illness, and decreases when the body is at rest or during sleep.

The medical definition of heart rate is:
“The number of heartbeats measured in beats per minute (bpm), which indicates the frequency of cardiac contractions and serves as a clinical indicator of cardiovascular health.”

Normal Heart Rate

The heart rate of a healthy person varies according to age, activity level, fitness, and overall health condition. However, there is a general range considered normal, which serves as a standard in clinical practice. The normal heart rate is usually measured in beats per minute (bpm).

1. Normal Resting Heart Rate in Adults
For healthy adults at rest, the normal heart rate ranges between 60 and 100 beats per minute. This rate ensures that the body receives adequate oxygen and nutrients while conserving energy. A resting heart rate closer to 60 bpm is often seen in physically fit individuals, while rates closer to 100 bpm may occur in people with lower fitness levels, anxiety, or certain medical conditions.

2. Normal Heart Rate in Children
Children generally have faster heart rates than adults because their metabolic needs are higher, and their hearts are smaller. For example:

• Newborns: 100–160 bpm
• Infants (up to 1 year): 90–150 bpm
• Toddlers and preschoolers: 80–140 bpm
• School-age children: 75–120 bpm
• Adolescents: 60–100 bpm (similar to adults)

3. Normal Heart Rate in Elderly People
In older adults, the resting heart rate usually remains within the 60–100 bpm range, but it may trend slightly higher due to age-related changes in the heart and blood vessels. However, a persistently high or very low heart rate in the elderly can indicate underlying disease.

4. Normal Heart Rate in Athletes
Athletes or people with high levels of physical fitness often have a resting heart rate below 60 bpm, sometimes as low as 40–50 bpm. This condition, known as athletic bradycardia, is not a disease but a sign of an efficient heart that pumps more blood with each contraction, reducing the need for frequent beats.

5. Variations in Heart Rate
The heart rate is not a fixed number. It changes throughout the day depending on physical activity, emotions, stress, body temperature, and sleep. During exercise, the heart rate rises to supply more oxygen to muscles, while during rest or deep sleep, it slows down.

Factors Affecting Heart Rate in Detail

Heart rate is not constant; it changes according to the body’s needs and external influences. Several physiological, emotional, and environmental factors can increase or decrease the number of heartbeats per minute. Understanding these factors helps in distinguishing normal variations from abnormal conditions that may require medical attention.

1. Physical Activity and Exercise
When a person engages in physical activity, the muscles demand more oxygen and nutrients. To meet this demand, the heart pumps faster, increasing the heart rate. During intense exercise, the rate can rise to 150–200 bpm, depending on age and fitness level. After exercise, the heart rate gradually returns to its resting level. The speed of this recovery is an indicator of cardiovascular fitness.

2. Fitness Level
People who are physically fit, especially athletes, generally have a lower resting heart rate. Their heart is stronger and pumps more blood with each beat, requiring fewer beats per minute to maintain circulation. This is why some trained athletes have a resting heart rate as low as 40–50 bpm.

3. Age
Heart rate naturally varies with age. Infants and young children have higher heart rates because of their higher metabolic rate and smaller heart size. As a person grows older, the resting heart rate decreases and stabilizes. In elderly individuals, slight increases may occur due to changes in heart tissue and blood vessels.

4. Emotions and Stress
Emotional states such as fear, anger, excitement, or anxiety stimulate the release of adrenaline, a hormone that increases heart rate. This is part of the body’s “fight or flight” response, preparing it to react quickly in stressful situations. Conversely, calmness, relaxation, and meditation can slow the heart rate by activating the parasympathetic nervous system.

5. Body Temperature
When the body temperature rises, such as during fever or exposure to heat, the heart rate increases. This happens because the body works harder to maintain normal temperature by circulating blood to the skin for cooling.

6. Medications and Substances
Certain medicines and substances can directly affect heart rate. For example, beta-blockers slow down the heart rate, while stimulants such as caffeine, nicotine, or some asthma medications increase it. Drugs that influence the nervous system can also cause irregularities in heart rate.

7. Health Conditions
Various medical conditions affect heart rate. An overactive thyroid (hyperthyroidism) increases heart rate, while an underactive thyroid (hypothyroidism) decreases it. Dehydration, anemia, infections, and heart diseases can also cause abnormal changes. In serious cases, irregular heartbeats or arrhythmias may develop.

8. Posture and Body Position
Heart rate may slightly vary depending on body position. For example, when a person suddenly stands up after lying down, the heart rate may briefly increase to maintain blood pressure and proper blood flow to the brain.

9. Sleep and Rest
During deep sleep, the heart rate slows as the body conserves energy and repairs itself. People who are sleep-deprived may have a higher resting heart rate, which increases strain on the heart over time.

10. Environmental Factors
External conditions like high altitude and humidity can influence heart rate. At high altitudes, the oxygen level in the air is lower, so the heart works faster to deliver enough oxygen to tissues. Similarly, in humid environments, the heart rate may rise as the body tries to cool itself.

Methods of Monitoring Heart Rate

Monitoring heart rate is essential for understanding how the heart responds to different conditions such as rest, exercise, stress, and illness. It also plays an important role in detecting early signs of cardiovascular disease. While measuring heart rate gives a snapshot at a single moment, monitoring allows continuous or repeated observation over time, which provides a clearer picture of overall heart function.

The simplest method of monitoring is manual pulse checking. This involves feeling the pulse at specific points like the wrist or neck at regular intervals and recording the beats per minute. Although this method is basic, it helps people keep track of whether their heart rate stays within a normal range during different activities. However, it is not always practical for long-term or continuous observation.

A more reliable approach is using a stethoscope for auscultation. Doctors and nurses listen directly to the heart, often at the chest, to assess both the rate and rhythm. This method provides a more precise reading than manual checking and allows the detection of abnormalities such as irregular beats or murmurs. In hospital settings, this is often done during routine examinations or when a patient shows symptoms of heart problems.

In modern healthcare and fitness, electronic devices are widely used for heart rate monitoring. Wearable heart rate monitors, such as chest straps and wristbands, can record beats continuously and are especially popular among athletes who need to track their heart’s response during training. Fitness trackers and smartwatches use optical sensors that detect blood flow under the skin and display heart rate in real time. These devices allow individuals to monitor their heart activity throughout the day and during different activities such as walking, running, or sleeping.

Pulse oximeters, which are small portable devices placed on the finger, also provide a simple way to monitor heart rate along with oxygen saturation. They are particularly useful for patients with respiratory or cardiac conditions and are commonly used at home or in hospitals for regular checks.

The most accurate method of monitoring is through an electrocardiogram (ECG or EKG). This test records the electrical activity of the heart using electrodes attached to the body. While a standard ECG gives a short recording, continuous ECG monitoring is often used in hospitals, especially in intensive care units, where patients are connected to bedside monitors.

Abnormal Heart Rate

A healthy heart maintains its rhythm within a certain range depending on age, activity level, and health status. When the heart beats too fast, too slow, or irregularly, it is referred to as an abnormal heart rate.

The most common type of abnormality is tachycardia, which means the heart beats faster than normal. In adults, a resting heart rate above 100 beats per minute is generally considered tachycardia. This condition can occur due to fever, dehydration, anxiety, or excessive intake of caffeine and nicotine. It is also associated with medical problems such as thyroid disorders, anemia, lung disease, or heart disease. Persistent tachycardia may reduce the efficiency of the heart, as the chambers do not have enough time to fill with blood before pumping it out. This can lead to dizziness, shortness of breath, chest pain, or fainting in severe cases.

The opposite condition is bradycardia, in which the resting heart rate falls below 60 beats per minute. In athletes and highly fit individuals, a slow heart rate is normal and reflects efficient cardiac function. However, in other people, bradycardia may be caused by aging of the heart’s electrical system, electrolyte imbalances, side effects of medications, or diseases such as hypothyroidism. If the heart beats too slowly, it may not supply enough oxygen-rich blood to the body, leading to fatigue, weakness, dizziness, confusion, or even fainting.

Stress, intense emotions, dehydration, fever, hormonal changes, or overuse of stimulants may alter the heart rate significantly. In such cases, once the trigger is removed or treated, the heart rate usually returns to normal.