The thresholds for a dangerous heart rate at rest or a maximum heart rate when active depend on age, sex, weight, and fitness level.
For example, someone who is very fit may be able to safely achieve a faster heart rate during exercise and a lower resting heart rate than someone who does not regularly exercise.
This article discusses normal heart rates and how too-high or too-low heart rates can be harmful to your health.
Dangerous Heart Rate vs. Normal
What a dangerous heart rate is for you depends on your personal targets, which a healthcare provider can help you set.
Though a normal resting heart rate for adults ranges from 60 to 100 beats per minute, you can have a resting heart rate outside this range that is perfectly fine for you. If you are very physically active, for example, a resting heart rate of 40 beats per minute may be your norm.A high heart rate during exercise is considered safe as long as you don’t exceed your maximum heart rate.
Maximum heart rate varies from person to person, but in general, you can figure out your maximum heart rate by subtracting your age from 220.
When Heart Rate Is Too High
Having a heart rate that’s considered too high is called tachycardia. In general, tachycardia refers to a heart rate that is above 100 beats per minute. Tachycardia can be dangerous, but isn’t always.
There are different types of tachycardia. A higher heart rate naturally occurs when you’re exercising, for example. You can also experience tachycardia during scary or stressful events, if you consume a lot of caffeine, or if you are a heavy smoker. An overactive thyroid is a medical condition that can cause a high heart rate.
Tachycardia can also occur when the electrical signals in your heart that cause it to beat are firing abnormally. Because your heart is beating faster than it should, it can’t fill back up completely. As a result, less blood is delivered to the rest of your body.
In some cases, tachycardia does not cause any symptoms. In others, it can cause:
Dizziness Fainting Pounding heartbeat Chest pain or pressure Shortness of breath Palpitations (fast-beating, fluttering, or pounding heartbeats) Tiredness
Frequently exceeding a safe maximum heart rate can be dangerous. This is because an overworked heart is less efficient at pumping blood throughout the body. This can result in loss of consciousness or heart attack.
Seek immediate medical attention if you experience a sudden or severe onset of any of these heart attack symptoms:
Chest pain or pressureJaw, arm, neck, or back painDifficulty breathingWeaknessDizziness/faintingFatigueNausea/vomiting
Tachycardia can lead to heart failure.
When Heart Rate Is Low
A heart rate that is considered too low is called bradycardia. This typically refers to a heart rate lower than 60 beats per minute for adults.
A low heart rate is not always abnormal. In fact, it can even be a sign of physical fitness.
For example, if you are an endurance athlete, your heart probably works very efficiently. Your normal heart rate could be closer to 40 or 50 beats per minute—or even lower. This means that your heart doesn’t have to pump as fast to deliver oxygen to the rest of your body.
Bradycardia can also be a symptom of underlying medical conditions, however. Low heart rate can occur when electrical impulses don’t travel along correct paths in the heart or when the structures that generate these electrical impulses are damaged.
Low heart rate can also occur with heart disease, heart attack, and other medical conditions such as hypothyroidism (underactive thyroid).
Symptoms of bradycardia are similar to those caused by a high heart rate. These can include:
DizzinessFaintingDifficulty breathingConfusionWeaknessTirednessLimited ability to exercise
Bradycardia can also lead to heart failure and changes in blood pressure (both high and low).
Dangerous Heart Rates in Children
Normal heart rates are higher in infants and children than adults. These numbers decrease as a child gets older.
It can be more difficult to know when a child is experiencing abnormal heart rates, especially if they are too young to talk. Older children might know that they feel faint or weak or are experiencing heart palpitations. Additional symptoms in younger kids can include:
Pale skinTirednessIrritabilityDifficulty feedingShortness of breath
When to See a Healthcare Provider
If you suspect that you or your child has a heart rate that is too high or too low, see your healthcare provider. You’ll likely have testing done to determine the cause of your symptoms.
An electrocardiogram (ECG or EKG) is commonly the first test performed to determine the cause of an abnormal heart rate. During this test, electrodes are attached to your chest (and sometimes arms or legs) to detect the electrical impulses as they pass through your heart.
Your doctor might also have you wear a portable heart monitor for a day (or longer) to record your heartbeat for longer periods of time.
Be sure to tell them about any medications you are taking, as certain drugs impact heart rate. For example, beta-blockers slow a person’s heart down, while decongestants can increase heart rate.
Summary
In general, the normal resting heart rate for adults is 60 to 100 beats per minute. However, heart rate varies from person to person, and your ideal heart rate might be higher or lower than this range.
Many factors can contribute to a change in heart rate, including exercising, consuming caffeine, smoking, and more. In some cases, a heart rate that is too high or too low can be a sign of underlying issues with the electrical impulses in your heart, or other medical conditions.
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