What Is a Normal Heart Rate Variability (HRV)?

Heart rate variability (HRV), or the difference in time between your heartbeats, is one of many measurable indicators of heart health. HRV can be associated with health conditions, similar to how blood pressure and cholesterol levels can indicate an underlying condition. Athletes may also be able to use their HRV to optimize training.

The average "good," or normal range, HRV among healthy adults is 19–75 milliseconds. A too-low HRV may indicate heart problems, such as an irregular heartbeat and heart failure. A high HRV, in contrast, can be a sign of cardiovascular fitness.

The human heart can beat more than 115,000 times a day. You might not pay any mind to the rate at which your heart beats, but how it varies can tell you a lot. Read on to learn what normal HRV is and what it can tell you about your health.

What Is Heart Rate Variability?

Heart rate is the number of times the heart beats per minute. HRV is a measure of the change in timing between successive heartbeats. Having variation in heart rate is not only completely normal but also necessary. Your heart is constantly keeping blood flow at a consistent level, keeping pace with your body's needs.

Your heart may beat at a steady rate of 60 beats per minute while you are resting. However, your heart rate may pick up to keep pace with your activities, such as if your alarm clock suddenly rings and you get up to face the day ahead.

Your heart rate also needs to increase during exercise to provide blood flow to your working muscles and distribute blood to carry oxygen throughout your body. If your heart rate did not increase, you would quickly become lightheaded and perhaps even faint.

Other factors that influence HRV include:

• Alcohol consumption
• Anxiety disorders, chronic stress, or depression
• Body mass index (BMI)
• Coffee consumption
• Genetics
• Inflammation and infection
• Physiological factors like age, circadian rhythm, and gender
• Smoking

How Does it Work?

The heart's electrical system controls heart rate. The electrical system sets heart rate based on what's happening with the:

• Body temperature
• Cardiovascular system
• Circadian rhythm
• Hormones
• Metabolism
• Nervous system
• Respiratory system

Each of these factors affects the beat-to-beat variation of the heart, which is responsible for HRV. You also have to consider the roles of the parasympathetic and sympathetic nervous systems.

The parasympathetic system is what's in control when you are at rest. The sympathetic nervous system is responsible for the "fight-or-flight" response. These two systems are counterparts closely tied to the heart rate and HRV.

Each breath you take impacts HRV through stimulation of the parasympathetic nervous system. The sympathetic nervous system releases the hormones of epinephrine or adrenaline when fight or flight kicks in. These hormones cause an increase in heart rate.

Benefits

Paying attention to your HRV can be a good thing. Benefits include:

• Better assessment of your lifestyle habits: Your HRV is influenced by modifiable factors, such as exercise, sleep, and stress. Too high or low of an HRV may clue you into what lifestyle changes may be beneficial for your health.
• Information that can influence workouts: Athletes may use HRV to plan their workouts. A high HRV can be ideal for high-intensity workouts, while a low HRV is good for rest days. Some evidence suggests that paying attention to your HRV can help minimize injury risk.
• Gained insight into your stress levels: A low HRV might indicate that your body is in "fight-or-flight" mode. This physiological response to stress is controlled by the sympathetic nervous system.

How To Check 

You need to have your heart monitored to measure HRV. This monitoring can last anywhere from less than five minutes to 24 hours. Medical devices such as an electrocardiogram (EKG), heart rhythm monitors, pacemakers, and internal cardiac defibrillators can all measure HRV.

Some people, like competitive athletes looking to improve their performance, want to measure their HRV at home. You can do this by wearing a fitness device, such as a smartwatch.

Heart Rate Variability Values

HRV can reveal information about cardiovascular health and fitness. Too high or too low of an HRV may indicate an underlying health concern.

High

A higher HRV is generally a good sign of heart health and cardiovascular fitness. Athletes tend to have greater degrees of cardiovascular fitness. Exercise training improves the heart's efficiency, resulting in a higher HRV.

Athletes may use HRV as part of specific training protocols to enhance endurance and performance. More research is needed to determine how best to incorporate HRV into training protocols.

A higher HRV doesn't always mean better heart health. Arrhythmias, which are potentially serious irregular heartbeats, can also cause high HRV.

Low

A reduced HRV is typically associated with an increased risk of death, arrhythmias, and heart attack. Abnormally low HRV has also been linked to early death, heart failure, and sudden cardiac death.

Aging can decrease HRV. Health conditions, such as inflammatory disease, chronic pain, mood disorders, and sleep disorders, may also lower HRV.

How To Improve Heart Rate Variability

Humans don't have control over many factors that influence HRV. Research has shown that HRV can be improved in a few ways, such as increasing exercise. Exercise trains your heart to pump more efficiently. Its effect on HRV may be due to its effect of stimulating the parasympathetic nervous system. Treatment of conditions linked to low HRV, such as chronic pain or sleep disorders, may also improve it.

Other factors that have been linked to an improved HRV include:

• Breathing exercises
• Meditation
• Stress reduction
• The Mediterranean diet

When To Contact a Healthcare Provider

It's time to see a healthcare provider if you're concerned about your heart health and notice abnormally low or high heart rate in relation to your activities. Worrisome signs could include a heart rate that doesn't increase with exercise or is racing while at rest.

Certain arrhythmias, such as atrial fibrillation (an irregular, often rapid heartbeat), can affect HRV. It's important to have a healthcare provider evaluate and treat these conditions.

A Quick Review

HRV is just one of many indicators of cardiovascular health and fitness. It's normal and healthy to have variability in heart rate throughout the day based on various activities. Athletes tend to have higher HRV, which corresponds with higher cardiovascular fitness. HRV data may be incorporated into some training protocols to improve endurance.

You can generally improve HRV with a structured exercise program. Other lifestyle changes, such as stress reduction and a healthy diet, may also help.

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