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What is heart rate? What should be the normal heart rate? To know more, read the full article.
In simple terms, heart rate can be defined as the number of times a heart beats per minute or the number of times the heart contracts per minute.
Heart rate indicates the number of times the heart is beating to pump out blood to the rest of the body through the arteries.
The measuring unit of heart rate is beats per minute. The heart rate is a clinical entity that is used by almost every healthcare professional.
A normal adult has a heart rate of 72 beats per minute. But the heart rate does not remain constant throughout the day.
Various factors determine the rate at which the heart should beat.
1. The Heart:
The adult human heart is divided into 4 chambers. The chambers are of two types.
The Atria and the Ventricle. The atria are also known as the upper chambers, and the ventricles are the lower chambers of the heart.1
The heart is divided into right and left sides, each side consisting of an atrium and ventricle.
The heart also consists of valves that prevent the backflow of blood.
Arteries and veins carry out the blood along with the heart and throughout the body.
1.1 The Conduction System:
The heart has special types of cells that can generate and conduct electric impulses. The heart has a special pathway for this electric impulse to travel, which forms the heart’s conducting system.
The pathway of the electric impulse is as follows:
- The SA NODE present in the right atrium can generate an electric impulse.
- This impulse is then passed to the AV NODE, which is present at the bottom of the right atrium.
- It then gets divided into right and left bundle branches.
- The impulse is then passed to the BUNDLE OF HIS, which is a collection of nerve fibers.
- These fibers then pass the electric impulse to the PURKINGE FIBERS, the end fibers, and supply the ventricles.
Let us now discuss the beating of the heart, that is the heart rate.
2. Normal Resting Heart Rate
Normal resting heart rate is when a person is resting or when no physical activity is carried out.
The normal range of a heart rate is 60 to 100 heartbeats per minute.
According to American Heart Association, the normal resting heart rate according to different ages is different and is not the same for everyone.
Even people belonging to the same age group may have different values.
3. Abnormal Heart Rate
An abnormal heart rate is known as Arrhythmia. It is a problem with the heart, a condition where a person’s heart might beat too slow, too fast, or in an irregular or unusual rhythm.
3.1 Bradycardia and Tachycardia
When the heart rate during the resting period ranges below 60 beats per minute, it is known as bradycardia.
It is common in older individuals.
When the heart rate in the resting period ranges above 100 beats per minute, it is known as tachycardia.
3.2 Sinus Bradycardia
Sinus bradycardia is caused when the SA node present in the heart sends out electrical signals at a slower rate leading to a lower heart rate.
3.3 Sinus Tachycardia
Sinus tachycardia is caused when the SA node present in the heart sends out electrical signals at a higher rate leading to an increase in the heart rate.
3.4 Supraventricular Tachycardia
It is also known as SVT.
When the lower chambers of the heart or the ventricles beat at irregular levels, it leads to SVT.
The heart rate increases and the heart beats at irregular levels.
4. How to Measure the Normal Heart Rate?
The heart rate can be calculated or measured easily at home without any device.
4.1 Steps:
- Sit in a comfortable position with your arm supported.
- Now place your index finger and middle finger on the radial artery. This artery can be easily located near the thumb on the ventral aspect of the forearm.
- Press lightly, and you will feel upbeat, which indicates that you have placed your finger on the radial artery.
- When the rhythm of the pulse feels constant, set a timer of one minute and begin counting. Count the number of beats that occur in one minute.
- The calculated value which is a number, is known as Pulse Rate.
The normal pulse rate is nothing but the heart rate.
5. Factors That Influence Heart Rate
5.1. Age/Gender
Heart rate usually differs according to age.
Children usually have a higher heart rate as compared to older individuals who have a lower heart.
Females usually have a higher rate as compared to males due to different metabolic demands.
5.2. Temperature
Normal Heart rate usually increases with an increase in body temperature.
The rate of the heart is affected by the position of the body. When the body is prone or lying down, the normal heart rate is reduced. It is usually considered a normal resting heart rate.
When the body is in a sitting or standing position, the heart rate slightly increases.
5.3. Emotions
The normal heart rate is highly affected by the emotional status of the body.
Anxiety, stress, panic attacks, fear, and all emotions cause an increase in the heart rate.
Also, euphoria, excitement, and appreciation change the heart rate.
5.4. Exercise and Stress Test
With vigorous physical activity, the normal heart rate increases.
While performing any exercise, the average maximum heart rate according to age should be known.
This is a very important tool in determining heart health.
This is an important indication in a stress test.
A Stress test is a medical test that determines cardiovascular health by measuring the heart rate with an increase in the body’s activity.
It is carried out on a treadmill under the invigilation of a certified healthcare provider.
The speed of the treadmill is gradually increased, and the electrical activity of the heart is recorded.
Moderate intensity activities to strenuous activities are performed by the person undertaking the stress test.
If the person has a healthy heart, he can undertake the stress test very well with reaching the target heart rate.
If any other medical condition or heart disease is present that causes cardiovascular deconditioning, the target heart rate is not reached, leading to further investigations.
The heart rate can also be calculated using an ECG.
The ECG records the heart’s electrical activity and converts it into a graph known as an electrocardiograph.
The ECG helps detect the abnormal electric activity of the heart and the part of the heart involved.
5.5. Hormones
Hormones have a great influence on heart rate.
The sympathetic nervous system2 releases hormones like epinephrine and norepinephrine, which increase the heart rate. Adrenaline, also known as the fight or flight hormone, released during a stressful situation, increases the heart rate.
The parasympathetic nervous system releases acetylcholine3 which decreases heart rate.
5.6. Medicines and Comorbidities
Individuals undertaking medicines have a direct effect on their heart rate. These medicines could be used to correct arrhythmia or improve cardiovascular conditioning or any other health condition.
Other associated health conditions may also increase the heart rate. Individuals prone to high blood pressure have an increased heart rate. Diabetic individuals also have a high heart rate as well as fluctuating blood pressure.
Individuals with overactive or interactive thyroid function and anemia also have a higher heart rate.
5.7. Parity
With the advancing gestational period, the heart rate increases. This can be considered dangerous.
This is caused due to an increase in the stroke volume and the body’s metabolic demands, increasing the risk of heart disease.4
5.8. Peripheral Resistance
Peripheral resistance is the resistance that the peripheral blood vessels offer to the blood flow.
The higher the resistance, the higher the heart rate.
6. How to Lower Down an Increased Heart Rate?
An increase in normal heart rate can cause a lot of distress to the individual.
Various signs can be noticed with an increased heart rate.
Following are the signals worth watching:
- Difficulty in breathing, also known as dyspnea
- Palpitations
- Nausea
- Confusion
- Headache
- Vomiting
- Sweating
- The feeling of heaviness in the chest
- Audible heart sounds
- Unable to stand or sit
- Poor concentration
- Chest pain
- Chest tightness
- Fainting or near fainting
- The feeling of a racing heart.
In such a situation, one must not start panicking but rather act purposefully.
6.1 Steps:
- Sit or lie down on a comfortable mattress
- Remove any tight type of clothing
- Make sure that the area is well-ventilated. Open all the windows and doors for proper ventilation.
- Call for help if the situation starts worsening
- Till the help arrives, start with deep breathing
- Inhale from the nose and slowly exhale from the mouth by making a narrow opening through the lips as if blowing out a candle.
- Continue this cycle at least 5 to 6 times per minute.
7. Conclusion
The normal resting heart ranges between 60 and 100 beats per minute. Various factors determine the rate at the very beats.
The palpation of the pulse is a direct measure to calculate the heart rate. The radial pulse is used to calculate the heart rate.
Regular exercise like yoga, cycling, and swimming, help maintain a healthy heart rate. It is best advised to exercise regularly in the target heart rate zone.
The exercise program should be fixed and must involve moderate-intensity activities. Exercises help to keep your heart strong. With proper exercise and physical fitness, you need to take good care of your diet too, since losing weight can lead to slowing your higher resting heart rate.
Regular heart health checkups by a recognized healthcare provider should be done. This is because your actual maximum heart rate or average heart rate can be most accurately determined by a professional only.
- Kang, Dongwoo, et al. “Heart chambers and whole heart segmentation techniques.” Journal of Electronic Imaging 21.1 (2012): 010901-010901. ↩︎
- Dibona, Gerald F. “Sympathetic nervous system and hypertension.” Hypertension 61.3 (2013): 556-560. ↩︎
- Hasselmo, Michael E., and James M. Bower. “Acetylcholine and memory.” Trends in neurosciences 16.6 (1993): 218-222. ↩︎
- Steenland, Kyle. “Passive smoking and the risk of heart disease.” Jama 267.1 (1992): 94-99. ↩︎
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