Heart rate variability, commonly abbreviated as HRV, is an accurate, non-invasive measure of the autonomic nervous system (ANS), the body’s main control system for self-regulation. HRV is widely considered the most comprehensive biomarker of health and fitness. Read on to learn how HRV is different from heart rate and how it can be used to improve your well-being.

What is heart rate variability and why does it matter?

Heart rate variability (HRV) is a measurement of the variation in time between successive heartbeats. You can track the indicator using an at-home sensor to get an important glimpse into how you respond to stress and how your health and well-being are trending.

Tracking HRV helps you:

• Tune in to your body so you can make smart, informed decisions about your health, fitness, and well-being.
• Prevent burnout from stress.
• Avoid overtraining.
• Identify risk of illness early to accelerate recovery.
• Track quantified progress over time to see when your health, fitness, and well-being are improving or declining.
• Stay accountable to your goals.

To understand HRV, it’s important to know that the human heart is not a metronome. A heart rate of 60 beats per minute suggests one beat per second; in reality, there are millisecond variations between successive heartbeats. Some beats are more like 0.9 seconds apart while others are more like 1.2 seconds apart. 

Oddly enough, the healthiest hearts don’t have more steady, consistent intervals. Instead, these hearts react and recover from stressors and soothers quickly, causing heartbeat intervals to vary. Because of that, a high HRV score is the healthiest.  

High HRV scores correlate with resilience, fitness, longevity, and strong mental health, while low HRV scores correlate with inflammation, reduced fitness levels, poorer health, and increased risk of chronic disease in the long term.

Tracking HRV creates a powerful feedback loop that can motivate behavioral change and make you more aware of how your lifestyle and habits impact your overall wellness goals.

HRV is not the same as heart rate

When people first discover HRV, they often confuse it with heart rate. However, the two indicators couldn’t be more different. Heart rate measures how many times your heart beats per minute, while HRV measures the changes in time (or variability) between successive heartbeats. The time between beats is measured in milliseconds (ms) and is called an “R-R interval” or “inter-beat interval (IBI).

While you can easily measure your heart rate by resting your finger on the inside of your wrist or the neck below the ear, HRV cannot be measured by touch. Calculating your HRV requires the use of a device that’s sensitive enough to calculate the exact number of milliseconds between each heartbeat.

Both heart rate and HRV are measurements of the heart. However, the power of HRV rests in its insight into the autonomic nervous system (ANS), the body’s main control system for self-regulation.

Learn More: Heart Rate Variability vs. Heart Rate

HRV and the autonomic nervous system

Even when the body is completely at rest, a grand balancing act — called homeostasis — is taking place. Homeostasis means “changing to stay the same,” and is central to understanding how even the simplest single-celled organisms stay alive. 

The principle of changing to stay the same is illustrated by the athlete pictured below who is working hard to stay on the slackline.

The athlete makes thousands of small adjustments in response to the gale forces that disturb their balance. This same phenomenon is happening inside your body every second of every day as you respond to the dynamic conditions of your life and surroundings. 

The variability we experience between heartbeats is a direct result of the autonomic nervous system fine-tuning our physiology in response to life’s ups and downs. 

How the body responds to and recovers from stress

The ANS helps us maintain homeostasis through its two branches: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PSNS).

The sympathetic nervous system (SNS) controls your body’s “fight or flight” reactions in response to internal and external stressors. It stimulates blood glucose (to fuel your muscles) and pupil dilation (to see the threat better), slows digestion (to focus energy on the present danger), and increases heart rate (to ensure adequate blood circulation to run or fight). 

The SNS is ideally activated to overcome short-term stress situations such as running from a tiger or fighting an intruder. However, the response also occurs when you exercise, perform challenging mental tasks, get in an argument, or even sit in traffic.

Learn More: Deep dive into the sympathetic nervous system with this video by CrashCourse.

The parasympathetic nervous system (PSNS) controls your “rest and digest” responses and is associated with recovery. Parasympathetic activation conserves energy, constricts pupils, aids digestion, and slows the heart rate. The PSNS is meant to help build for the long term and is needed to grow faster, stronger, and healthier.

Learn More: Delve into the parasympathetic nervous system with this video by CrashCourse.

What gives rise to heart rate variability?

Think of the body like a race car: The SNS is like the accelerator, revving you up in stressful situations, and the PSNS is like the braking system, returning the body to a resting state after the stressor has passed. 

With every heartbeat, your nervous system says “slow down” or “speed up” based on feedback from your senses and emotions. As you navigate the world, your ANS sets the relative balance of the SNS and PSNS based on what’s happening at that moment.

Balance leans toward parasympathetic

Sometimes, this balance leans toward the SNS (like when something stressful is happening). Other times, it leans toward the PSNS (like when you’re sleeping or chilling out).

What is autonomic fitness?

For our body to maintain optimal health and well-being, both our braking system (the PSNS) and our accelerator (the SNS) need to function. When both these systems are working well, we can respond to stress quickly and return to normal just as fast.

Have you ever witnessed a young child in distress — loudly crying one moment, yet happily playing a minute later, the stress immediately forgotten? Children are resilient, and often have high HRV scores and autonomic fitness, which helps them bounce back from stress like rubber bands. 

Many older adults, on the other hand, need time to adjust after periods of high emotional stress. Thus, it takes longer for their ANS to return their physiology to a resting state. 

We explore this and more about the science of longevity in a discussion with Dr. Joon Yun, founder of the Palo Alto Longevity Prize.

How does HRV relate to overall well-being?

The SNS’s response to stress focuses on short-term survival as opposed to long-term health. This acute response can become chronic in the presence of stress from daily life, such as work, relationships, financial, environmental, dietary, physical, and lifestyle choices. Chronically accumulated stress from multiple sources can contribute to drastically reduced health and performance over the long term.

A high HRV is a good indicator that your body is equipped to respond to stress and is correlated with increased resilience and emotional control. When you encounter uncomfortable, stressful, or even traumatic situations, you are more likely to show flexibility and adaptability.

Similarly, low HRV is correlated with mental disorders, including anxiety and depression. In extreme cases, low HRV can indicate dysfunction of the autonomic nervous system. HRV has even been shown to be a predictor of psychological illness up to 10 years in the future. 

A significant amount of research published over the past 50 years correlates heart rate variability to:

• Disease risk and progression (diabetes, cardiovascular disease, respiratory diseases, gastrointestinal diseases, autoimmune conditions, etc.)
• Morbidity and mortality
• Biological aging and health
• Mental health, mood, depression, anxiety, PTSD
• Physical performance 
• Injury prevention
• Guided rehabilitation
• Mental cognition

A low HRV is not necessarily a bad thing — it could simply be a signal that you need to eat a more nutritious diet or eat at regular hours. A low HRV can also help you realize that you’re working too many hours or not sleeping enough to allow your body to recover.

Learn More: Is a higher HRV always ‘better’?

What is a normal HRV?

Heart rate variability is based on individual circumstances. Everything from your mindset, air quality, age, and exercise patterns can affect HRV. This is why we emphasize personal trends and improvement over comparing ourselves to others. If you want to get a sense of where your HRV should be, you can browse the HRV scores of others within your population demographic. For example, the average HRV score for Elite HRV users is 59.3. 

Since many factors influence HRV, the “normal” HRV will vary by age and gender, and lifestyle. Scoring low on any given day is usually nothing to worry about. It is your average HRV over time that matters most.

Histogram data of HRV scores for 24,764 Elite HRV users.

What is a good HRV? 

You may be asking yourself, “what is a good HRV score?” or “what is a healthy HRV score?” The answer is not so straightforward. 

Many factors influence HRV, so it is difficult to give a specific number that would be a good HRV score for each individual. However, it can be helpful to see how you compare to others in your age group. The table below is a comparison of the average HRV scores, categorized by age ranges and gender.

Table 2. Data from 10,308 Elite HRV users showing ln(rMSSD) and Elite HRV Score presented by age range and gender.

Learn More: Check out our page on Normative HRV Scores by Age and Gender to see how you compare to others in your age group.

Since many Elite HRV users tend to be people who strive to live healthy lifestyles, the ranges in the table above tend to be considered a “good” range for that gender and age group. So, if you fall within that range for your gender and age group, then you likely have a “good” HRV score. 

For example, if you are a 28-year-old woman with an HRV score of 66, which falls within the range of 61.83 plus or minus 10.59, then you probably have a “good” HRV score. 

Ideally though, instead of using others’ HRV scores for comparison, you should begin to monitor your HRV scores regularly and look for upward trends as you incorporate positive changes into your lifestyle. In general, you should expect to see an upward trend in HRV scores as you incorporate those healthy changes into your routine. 

It’s important to note that your daily HRV scores can go up or down daily so look at your HRV trends over time rather than from day to day. 

What factors affect HRV? 

A few of the primary factors that impact heart rate variability include sleep, nutrition and physical activity, but the research shows that there are many known factors that affect HRV. 

1. Lifestyle
   • Sleep
   • Nutrition
   • Exercise
   • Alcohol consumption
   • Tobacco or drug usage
2. Training
   • Volume
   • Intensity
   • Exercise
   • Unfamiliar stimuli
3. Biological
   • Age
   • Gender
   • Ethnicity
   • Genetics
   • Illness
4. Mental Health
   • Stress
   • Depression
   • Anxiety
   • Emotions
   • Medication
5. Environment
   • Chemical exposure
   • Exposure to electromagnetic fields (EMF)
   • Air quality
   • Work schedule
   • Usage of vibrating tools

Table 1. A list of some factors that influence HRV, categorized by environmental, lifestyle, and biological factors.

How to improve your HRV score

If you decide your HRV is not quite where you want it to be, there are plenty of ways to improve your HRV score. Look at the previous table that lists the lifestyle factors that can affect your HRV and consider which factors are low-hanging fruit for you. Some easy fixes include:

1. Exercise

Exercise is essential for overall health. Pay attention to your body and focus on balancing regular training and recovery to increase your HRV. Don’t push too hard or ignore it when you’re tired or in pain. Have active recovery days with activities like walking or yoga to incorporate movement with minimal stress.

2. Eat Well

A review of the impact of diet on HRV found that HRV can determine the positive or negative impact of diet on overall health. Processed food and sugar can wreak havoc on your body and boost stress hormones, both of which will negatively affect your HRV. Aim to eat whole, fresh, anti-inflammatory foods that nourish your body. Consider adjusting your micronutrients or taking supplements to boost your HRV. Nutrition isn’t just about what you eat — pay attention to when you eat, too. Eating at predictable times is a great way to establish a healthy HRV. 

3. Drink More Water

Dehydration is a surefire way to put unnecessary physical and mental stress on the body. Your heart rate and blood pressure both increase when your body is dehydrated. Keep a water bottle handy to decrease your risk.

4. Limit Your Alcohol Intake

Just a single night of drinking can negatively impact your HRV by decreasing PSNS activation. When PSNS activation is limited, your body does not recover properly. 

5. Prioritize Sleep

A night of tossing and turning can trigger your sympathetic nervous system. Appropriate quality and quantity of rest, on the other hand, encourage your parasympathetic nervous system to kick into gear. HRV scores can be used to screen people with sleep disorders. If you consistently have trouble sleeping and have low HRV scores, consult a doctor to determine whether you have a condition that disrupts your sleep. 

6. Prioritize Mental Health

Stress isn’t just emotional — it creates physical changes in your body by activating the SNS. 

If you live a high-stress lifestyle or you’re struggling with anxiety or depression, it will impact your body and overall health. Reach out to a therapist to address your mental health. The connection and encouragement signal a sense of safety to your body, which helps you better recover from stress. 

7. Build emotional resilience

Learning how to control your emotions can also help improve HRV scores. Positive and negative feelings can directly impact HRV. When you feel negative emotions coming on, take a few deep breaths and work to control those feelings. Various breathing exercises can help you relax and may help when dealing with difficult emotions. 

8. Breathe

HRV biofeedback breathing (HRV-BF), also called HRV training, is one of the most important and effective tools for boosting health. You can increase your HRV by using a feedback or breath-pacing device to slow your breathing, which helps increase the variability of your heart rate. One technique requires you to slow down your breathing to six breaths per minute.

9. Meditate

Meditation is another powerful technique to reduce stress and improve HRV scores. Some meditation methods teach you to focus on your breathing or the sensations throughout your body. Find one you like so you’ll be better able to commit to it.

If you want to improve your HRV and you’re just getting started, there’s a simple three-step process that you should follow. Read more here: “How to make sense of your HRV.”

What are HRV trends and how can you spot them? 

As you begin to make healthy changes to your lifestyle you should begin to see an overall upward trend, objective feedback that you’re getting healthier.

The chart below is an illustration of daily HRV scores over 50 days. While the day-to-day scores are not always in an upward direction, there is an overall upward trend by day 50. That means that health and fitness are trending in the right direction and the person is likely getting healthier.

Scatter Plot. Illustration of daily resting HRV scores plotted over 50 days during the incorporation of a healthy diet and regular exercise.

Sometimes, the trend shows a downward slope over a period of weeks or months. This could be the result of overtraining, poor sleep, unhealthy nutrition, or high physical or mental stress. Even environmental factors that you may not have considered, like high exposure to electromagnetic fields (EMF) due to increased mobile phone usage, can affect your scores. A recent or oncoming illness can also cause a dip in HRV. 

Think about which lifestyle modifications are possible to ensure you give your body the right nutrition and the ability to recover from a hard day’s work and exercise. Remember that the SNS and PSNS systems are working to balance the heart rate, so it’s important to allow your body to recover, especially after stress, including long or intense exercise regimens.  

As you age, your HRV trend will eventually decrease. However, maintaining a healthy lifestyle can keep you at peak performance.

Learn More: How to make sense of your HRV

How to track your HRV

The Elite HRV app makes tracking and understanding your HRV easy. The app lets you tag your HRV measurements with the important things going on in your life, helps you analyze the results, and provides daily HRV-based guidance.  

So, join our thriving community of self-improvers and start learning about your HRV today.

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References

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