Heart Rate Variability

Heart rate variability is the natural variation of timing between heartbeats. High variability indicates better health and a strong ability to adapt to stress, while low HRV is a valuable predictor of some severe health conditions.

Key Takeways

• Definition: Normal heart rate variability (HRV) measures the variation in time between heartbeats, indicating autonomic nervous system balance.
• Health Indicator: Low average heart rate variability may signal future health problems, such as high blood pressure, while higher HRV is common in healthy adults.
• Monitoring: Wrist-worn fitness devices and chest strap monitors can track HRV.
• Circadian Rhythm: HRV follows the body’s circadian rhythm, with variations throughout the day.
• Lifestyle Impact: Good lifestyle habits, like regular exercise and stress management, improve HRV.
• Warning Sign: Extremely low HRV can indicate a medical emergency.

What is Heart Rate Variability?

The heart doesn’t beat in perfect time like a metronome. Heart rate variability (HRV) measures the time variation between heartbeats or “RR intervals.”

Heart rate variability can be used to evaluate the balance between the sympathetic and parasympathetic branches of the autonomic nervous system.

The autonomic nervous system controls the body’s “fight or flight” and “rest and digest” responses. Evaluating the complex relationship between these nervous system branches can help measure and predict overall health.

A higher level of heart rate variability is generally associated with better health.

The Connection Between Heart Rate Variability and Overall Health

Heart rate variability can be useful for assessing overall health alongside other health markers.

Healthy individuals generally show higher heart rate variability - as in, more variance between heartbeat timing - associated with a lower risk of cardiovascular disease (CVD) and diabetes.

High HRV indicates that the body is more able to adapt to stressors and maintain cardiovascular function, leading to lower rates of disease and lower rates of all-cause mortality.

As an Indicator of Other Conditions

Research has shown that heart rate variability effectively indicates many health conditions, including:

• Diabetes
• Cardiovascular disease
• Depression
• Anxiety
• Premature death.

A low HRV may indicate poor autonomic nervous system functioning in people with cardiovascular disease, leading to arrhythmia (irregular heartbeats) and heart failure.

Heart rate variability measurements may be helpful in determining someone’s current level of health and predicting future health issues.

Influences on Heart Rate Variability

Many factors can impact heart rate variability within and outside the body.

Lifestyle, diet and nutrition, and stress are some of the most influential factors through various mechanisms in the autonomic nervous system.

Autonomic Nervous System

The autonomic nervous system controls the body’s subconscious functions, like breathing, heartbeats, and digestion.

It has two branches, sympathetic and parasympathetic, which work in opposition. Heart rate variability is controlled by the autonomic nervous system, with the two branches having different influences on HRV.

Sympathetic Nervous System

Responsible for the body’s “fight or flight” mode, the sympathetic nervous system primes the body for action.

In stressful or exciting situations, the body activates its sympathetic nervous system, causing physiological changes, including increased blood pressure and heart rate, stress or anxiety, and heightened awareness.

Along with this priming of the body for action, heart rate variability decreases, meaning the time between heartbeats is more consistent.

Pulse increases, too, meaning heartbeats are both closer together and more uniform.

Parasympathetic Nervous System

The parasympathetic nervous system is active during daily living and provides the body’s “rest and digest” actions or relaxation response.

Blood pressure, respiratory rate, and pulse decrease in periods of low stress and relaxation when the parasympathetic nervous system is dominant.

The parasympathetic nervous system triggers higher heart rate variability, meaning less stress on the cardiovascular and cardiorespiratory systems.

In relaxing or non-stressful situations, HRV increases, meaning more timing variability and longer periods between heartbeats.

Lifestyle Factors

Lifestyle factors have a significant impact on heart rate variability.

Habits generally associated with poor health tend to decrease heart rate variability:

• Inactive or sedentary lifestyles
• Poor sleep habits
• Poor nutrition
• Smoking
• Heavy drinking
• Obesity
• Chronically high-stress levels

General Health

Healthy, active people tend to maintain a higher, more healthy level of heart rate variability when compared to sedentary and unhealthy populations.

Heart rate variability is used as a marker of general health; therefore, one can improve one's heart rate variability by living a healthy lifestyle.

Heart Rate Variability and Stress

Stress is one of the largest influences on heart rate variability. Unhealthy stress levels are associated with poor general health, and the relationship to heart rate variability reflects this.

How Heart Rate Variability Reflects the Body’s Stress Response

Heart rate variability shows the balance between the sympathetic and parasympathetic nervous systems.

A high HRV indicates that the body has a healthy stress response, while a low HRV shows an inability to adapt to and cope with stress, which can cause poor health if not properly managed.

HRV measurements can be a key tool for evaluating and improving the body’s stress response.

Acute

Acute stress is the stress felt briefly in a specific situation, like running late for work or arguing with a loved one.

In these acute stress scenarios, the sympathetic nervous system overrides the parasympathetic system, leading to higher blood pressure, a quickened pulse, and lower heart rate variability.

Fight or flight response is a survival tool and is not inherently bad; activating the sympathetic system allows for heightened senses and faster reaction time in stressful situations.

Alongside higher blood pressure and a quicker respiration rate, lower heart rate variability primes the body for immediate action.

Chronic

If stressful situations persist and the body runs on the sympathetic system for an extended period, this is known as chronic stress.

Long-term sympathetic nervous system activation increases the risk of chronically low HRV and poor health.

Chronic stress is known as “the silent killer” because of its association with much higher rates of physical and mental health disorders.

A chronically low HRV may indicate a high-stress lifestyle; managing stress is critical to improving HRV.

Treating Stress

Improving heart rate variability by reducing stress can reduce the chances of serious disease and improve quality of life.

HRV is not the only indicator of stress nor the only health marker that stress affects.

Still, a stress management routine incorporating physical activity, adequate rest, a healthy diet, and fewer stressors can reduce chronic stress and increase heart rate variability.

Measuring Heart Rate Variability

The time between heartbeats is very short, meaning the tools to measure HRV must be highly precise.

HRV measurements calculate the variation in time between heartbeats, not just the time itself.

HRV varies significantly from person to person and from situation to situation, meaning that one measure at one point may not indicate an overall trend.

It’s important to track heart rate variability over time to see the whole picture.

Clinical

Clinical heart rate variability metrics are used to assess heart rate variability at one point.

The gold standard for HRV measurement is the electrocardiogram (ECG), but doctors also use photoplethysmography (PPG) technology to measure heart rate variability.

HRV data are then analyzed with specific software to calculate HRV parameters and give a picture of heart rhythm.

Because so many factors influence HRV, one data point from one doctor visit doesn’t necessarily indicate a healthy heart or a health problem.

HRV data should be considered alongside other health markers.  

At-Home

Some at-home methods to measure heart rate variability include wearable heart rate monitors, smartwatches, and other wrist devices.

Regular HRV measurements from these devices can track heart rate variability, showing someone’s normal HRV trend.

While these data can be useful to measure a person’s HRV, they should always be considered alongside the recommendations of a medical professional before making any significant life changes based on personal data.

Improving Heart Rate Variability: Tips and Strategies

Like any aspect of fitness, heart rate variability can be improved. A proper diet, lots of physical activity, and a low-stress life can help to eliminate low heart rate variability and improve health.

Exercise

Physical fitness is one of the most critical components of a healthy life.

A healthy cardiovascular system improves the body’s ability to manage stress and can increase heart rate variability.

Regular exercise improves heart health, reduces heart problems, and improves mental health by releasing endorphins.

Mindfulness and Meditation

Because of their close relation to stress levels, mindfulness and meditation can lead to a higher HRV.

Meditation is one of the best ways to manage both acute and chronic stress, leading to a higher HRV.

Practicing mindfulness or meditation and working toward a healthy work-life balance can drop chronic stress levels and reduce sympathetic nervous system activation.

Supplements, Nutrients, and Dietary Changes

Healthy eating, limiting alcohol consumption, avoiding smoking, and not using drugs are all associated with a higher HRV.

Some experimental evidence shows that some supplements can be used to manage stress like Ashwagandha and Rhodiola rosea.

It’s also essential to give the body all the nutrients it needs, like zinc and magnesium, to promote heart health and reduce stress, improving heart rate variability.

Biofeedback

Biofeedback combines the body’s natural senses with external measuring tools to provide feedback.

For heart rate variability, biofeedback measures the nervous system's activity through:            

• Respiratory rate
• Blood pressure
• Pulse

This information is relayed to the patient as they practice relaxation strategies while receiving real-time feedback on their nervous system activity.

Biofeedback aims to equip the patient with tools to regulate the balance between sympathetic and parasympathetic activity and often incorporates deep breathing, meditation, and relaxation.

Learning to manage the fight or flight system and switch to rest and digest mode can drop chronic stress, raise HRV, and improve general health, especially over long periods.

Frequently Asked Questions

Is it Better to Have High or Low Heart Rate Variability?

Higher levels of heart rate variability are better than low HRV.

High HRV is associated with better health and indicates the body is better equipped to adapt to stress. Lower heart rate variability indicates that the body struggles to cope with stress and may predict poor health outcomes.

Can Heart Rate Variability Predict Bad Health Outcomes?

Yes, heart rate variability can be used when predicting bad health outcomes.

Studies have shown that a low HRV may predict a myocardial infarction (heart attack) or complete heart failure, among other conditions.

Should I Measure My Heart Rate Variability?

It wouldn’t hurt to measure HRV, but it’s important to remember that heart rate variability isn’t the end-all of health information.

HRV data should be considered alongside other measures of health. Talk to a doctor before making significant health-related changes based on personal HRV data.

The contents of this article are provided for informational purposes only and are not intended to substitute for professional medical advice, diagnosis, or treatment. It is always recommended to consult with a qualified healthcare provider before making any health-related changes or if you have any questions or concerns about your health. Anahana is not liable for any errors, omissions, or consequences that may occur from using the information provided.

References

Respiratory Sinus Arrhythmia - an overview | ScienceDirect Topics

Heart rate variability in myocardial infarction and heart failure - ScienceDirect

Stress and Health: Psychological, Behavioral, and Biological Determinants

Heart rate variability: How it might indicate well-being - Harvard Health

Heart rate variability - Wikipedia

Everything You Should Know About Heart Rate Variability (HRV) 

Heart Rate Variability Monitors & HRV Compatible Gadgets 

Disclaimer

The contents of this article are provided for informational purposes only and are not intended to substitute for professional medical advice, diagnosis, or treatment. It is always recommended to consult with a qualified healthcare provider before making any health-related changes or if you have any questions or concerns about your health. Anahana is not liable for any errors, omissions, or consequences that may occur from the use of the information provided.