The Foundation of Heartify’s Personalized Insights
Science
National Library of Medicine:
Applying Heart Rate Variability to Monitor Health and Performance in Tactical Personnel: A Narrative Review
DID YOU KNOW?
Every year, millions of people worldwide die from cardiovascular disease.
According to the World Health Organization, this is the no. 1 cause of death globally - so it is crucial to be proactive to prevent heart problems in the future. One of the indicators which help monitor heart health is HRV.
National Library of Medicine:
Heart Rate Variability: New Perspectives on Physiological Mechanisms, Assessment of Self-regulatory Capacity, and Health risk. (McCraty R, Shaffer F.)
What Is Heart Rate Variability?
HRV
Heart rate variability is an important indicator of overall cardiovascular health. It shows how your nervous system functions and the ability to respond to physical, mental, and emotional stressors. In recent years, there has been a resurgence of interest in HRV, thanks partly to technological advances that have made measuring more accessible.
Heart rate variability, or HRV, is a measure of time between each heartbeat, known as RR intervals. In other words, if your heart rate is 80 beats per minute, there may be 0.7 seconds between two beats or more – 1.20 seconds.
National Library of Medicine:
Real-world heart rate norms in the Health eHeart study (Robert Avram, Geoffrey H. Tison, Kirstin Aschbacher, Peter Kuhar, Eric Vittinghoff, Michael Butzner, Ryan Runge, Nancy Wu, Mark J. Pletcher, Gregory M. Marcus, and Jeffrey Olgin)
HRV VS. HR
Heart rate and heart rate variability are two different but interconnected measures. Your heart rate, also known as your pulse, is the number of times your heart beats per minute. An average resting heart rate should be between 60 to 100 beats per minute, but it can vary from minute to minute. While your pulse may feel consistent, the timing between heartbeats fluctuates.
HRV is the measure of the time interval between each heartbeat. These two are connected because HRV is affected by your heart rate. If your heart rate is too high, it can cause your HRV to be low. If your heart rate is too low, your HRV will increase. The ideal situation is to have a balance between the two measures.
HRV is the measure of the time interval between each heartbeat. These two are connected because HRV is affected by your heart rate. If your heart rate is too high, it can cause your HRV to be low. If your heart rate is too low, your HRV will increase. The ideal situation is to have a balance between the two measures.
What Is The Difference Between HRV And Heart Rate?
History
When did the history of HRV begin?
III-II century BC
The first written heart rate reports are established in the literature of Greek scientist Herophilos. Later, Archigenes continued his research and described the pulse and its characteristic features such as rate, rhythm, and volume.
1733
In 1733, Rev. Stephen Hales was the first one to demonstrate beat-to-beat variation and arterial pressure variation occurring during respiration.
1900
The concept of heart rate variability was later proposed in the early 1900s by Dr. Wilhelm Einthoven, who developed the first electrocardiogram (ECG). Dr. Einthoven noticed that the intervals between successive heartbeats were not always equal and proposed that this variability could be used to assess cardiac function.
1968
In 1968, American physiologist William Haslam Rosenbaum published a paper in which he used HRV to evaluate the autonomic nervous system.
1976
The breakthrough was in 1976 when Dr. Alan Waage and colleagues at the Norwegian Institute of Public Health found that patients with low HRV were at increased risk of death from cardiovascular disease over a follow-up period of 12 years. Since then, numerous studies have confirmed the predictive value of HRV for cardiovascular mortality.
1991
Cerulli introduced spectral analysis of HRV in rats in 1991. A year later, Zieglac introduced HRV spectral analysis in humans.
1996
Later in 1996, the European Society of Cardiology and the North American Society of Pacing and Electrophysiology defined the standards and guidelines to measure and interpret the HRV in the context of Healthcare.
2003
A study published in 2003 found that athletes who used HRV to monitor their training had a significantly lower risk of overtraining than those who didn't. This was one of the first studies to show the value of HRV for athletes.
2010
In 2010, Garmin released the first commercial HRV device, the Forerunner 610. This was a game-changer for athletes because it made HRV data more accessible and easier to use. Before the Forerunner 610, athletes had to go to a lab or clinic to get their HRV data. Now they can get it from their wristwatch.
2018
In 2018 alone, there were over 1,000 articles published on PubMed about heart rate variability. This shows just how far HRV has come in the past decade and how widely accepted it has become for well-being.
2020
The release of the Heartify App in 2020 - is a new and innovative way to calculate your heart rate variability, which shows accurate results about the condition of the heart. This marked the next level of heart measurements.
III-II century BC
The first written heart rate reports are established in the literature of Greek scientist Herophilos. Later, Archigenes continued his research and described the pulse and its characteristic features such as rate, rhythm, and volume.
1733
In 1733, Rev. Stephen Hales was the first one to demonstrate beat-to-beat variation and arterial pressure variation occurring during respiration.
1900
The concept of heart rate variability was later proposed in the early 1900s by Dr. Wilhelm Einthoven, who developed the first electrocardiogram (ECG). Dr. Einthoven noticed that the intervals between successive heartbeats were not always equal and proposed that this variability could be used to assess cardiac function.
1968
In 1968, American physiologist William Haslam Rosenbaum published a paper in which he used HRV to evaluate the autonomic nervous system.
1976
The breakthrough was in 1976 when Dr. Alan Waage and colleagues at the Norwegian Institute of Public Health found that patients with low HRV were at increased risk of death from cardiovascular disease over a follow-up period of 12 years. Since then, numerous studies have confirmed the predictive value of HRV for cardiovascular mortality.
1991
Cerulli introduced spectral analysis of HRV in rats in 1991. A year later, Zieglac introduced HRV spectral analysis in humans.
1996
Later in 1996, the European Society of Cardiology and the North American Society of Pacing and Electrophysiology defined the standards and guidelines to measure and interpret the HRV in the context of Healthcare.
2003
A study published in 2003 found that athletes who used HRV to monitor their training had a significantly lower risk of overtraining than those who didn't. This was one of the first studies to show the value of HRV for athletes.
2010
In 2010, Garmin released the first commercial HRV device, the Forerunner 610. This was a game-changer for athletes because it made HRV data more accessible and easier to use. Before the Forerunner 610, athletes had to go to a lab or clinic to get their HRV data. Now they can get it from their wristwatch.
2018
In 2018 alone, there were over 1,000 articles published on PubMed about heart rate variability. This shows just how far HRV has come in the past decade and how widely accepted it has become for well-being.
2020
The release of the Heartify App in 2020 - is a new and innovative way to calculate your heart rate variability, which shows accurate results about the condition of the heart. This marked the next level of heart measurements.
National Library of Medicine:
Stress and Heart Rate Variability: A Meta-Analysis and Review of the Literature (Hye-Geum Kim, Eun-Jin Cheon , Dai-Seg Bai, Young Hwan Lee, Bon-Hoon Koo)
National Library of Medicine:
Anatomy, Autonomic Nervous System (Joshua A. Waxenbaum; Vamsi Reddy; Matthew Varacallo)
HRV and ans
The hypothalamus is a small region in your brain that processes information and sends signals to the rest of your body through what we call "the autonomic nervous system". The ANS handles about 90% of automatic functions, including heart rate, blood pressure, respiration, and digestion.
The autonomic nervous system is a complex web of interconnected systems and consists of two parts – the sympathetic and parasympathetic nervous systems. The SNS increases the heart rate while activating "the fight-or-flight response." The PSNS does the opposite; it slows the heartbeat and controls the natural relaxation response.
The autonomic nervous system is a complex web of interconnected systems and consists of two parts – the sympathetic and parasympathetic nervous systems. The SNS increases the heart rate while activating "the fight-or-flight response." The PSNS does the opposite; it slows the heartbeat and controls the natural relaxation response.
How does it work: HRV and the autonomic nervous system?
The parasympathetic nervous system is responsible for the body's rest and digestion response when the body is resting or feeding. It slows down the heart rate and widens blood vessels.
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The sympathetic nervous system reflects responses to things like stress and exercise. This branch of the autonomic nervous system increases heart rate and blood pressure and constricts blood vessels.
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When these systems are in balance, your body can function at its best. HRV arises from these two opposing branches concurrently sending signals to your heart. A high HRV indicates that the sympathetic and parasympathetic systems work well together, and the body can adapt quickly to physical, mental, and emotional stressors. A low HRV may signify that the sympathetic nervous system is dominant and can lead to increased anxiety, difficulty sleeping, and other symptoms of stress. If one has a low HRV, it is essential to take steps to reduce stress and promote relaxation.
Journal of the American Heart Association
Heart Rate Variability for Risk Assessment of Myocardial Ischemia in Patients Without Known Coronary Artery Disease: The HRV-DETECT (Heart Rate Variability for the Detection of Myocardial Ischemia) Study
National Library of Medicine
Autonomic balance revisited: panic anxiety and heart rate variability (B H Friedman, J F Thayer)
National Library of Medicine
Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry (Suzanne C. Segerstrom and Gregory E. Miller)
National Library of Medicine
Obesity, Nutrition and Heart Rate Variability (Anna Strüven, Christina Holzapfel, Christopher Stremmel, and Stefan Brunner)
Juan Sztajzel
Heart rate variability: a noninvasive electrocardiographic method to measure the autonomic nervous system
Nocturnal heart rate variability in obstructive sleep apnoea: a cross-sectional analysis of the Sleep Heart Health Study
Matteo Bradicich, Noriane A. Sievi, Fabian A. Grewe, Alessio Gasperetti, Malcolm Kohler, Esther I. Schwarz
Using HRV
HRV is a great way to assess health and see what is happening with the heart. You can monitor the risk of developing heart disease and hypertension, track the immune response, and get an idea of how your body responds to training, life stressors, and recovery from workouts.
Why does HRV matter?
Assessing the risk of death or cardiovascular disease
Today, people use HRV for different things, including:
Identifying ANS imbalances
Tracking progress of rehabilitation after a heart attack
Diagnosing sleep apnea
Providing insights into psychological stressors
Detecting stress levels
Reassessing your lifestyle habits
Boosting the immune system
Maintaining mental health
National Library of Medicine
Are Changes in Heart Rate Variability in Middle‐Aged and Older People Normative or Caused by Pathological Conditions? Findings From a Large Population‐Based Longitudinal Cohort Study (Vera K. Jandackova, PhD, Shaun Scholes, PhD, Annie Britton, PhD, and Andrew Steptoe, DSc)
National Library of Medicine
Age and Sex Differences in Heart Rate Variability and Vagal Specific Patterns – Baependi Heart Study (Glaucylara Reis Geovanini, MD, MPH, PhD, Enio Rodrigues Vasques, Rafael de Oliveira Alvim, José Geraldo Mill, Rodrigo Varejão Andreão, Bruna Kim Vasques, Alexandre Costa Pereira, and Jose Eduardo Krieger)
National Library of Medicine
Reference values of heart rate variability from 10-second resting electrocardiograms: the Lifelines Cohort Study (Balewgizie S Tegegne, Tengfei Man, Arie M van Roon, Harold Snieder, Harriëtte Riese)
MDPI
Analysis of Short-Term Heart Rate Asymmetry in High-Performance Athletes and Non-Athletes
(Yecid Mina-Paz, Victoria Noemí Santana-García, Luis Javier Tafur-Tascon, Moisés Arturo Cabrera-Hernández, Adriana Cristina Pliego-Carrillo and José Javier Reyes-Lagos)
(Yecid Mina-Paz, Victoria Noemí Santana-García, Luis Javier Tafur-Tascon, Moisés Arturo Cabrera-Hernández, Adriana Cristina Pliego-Carrillo and José Javier Reyes-Lagos)
HRV norms
The human heart’s natural frequency is detected by how fast it beats and intervals between successful heartbeats. It tends to decline in age, which reflects the normal aging process. Younger people tend to have higher HRVs than older people, and males may have slightly higher HRVs than females.
HRV (RMSDD) vs. Age
Below is a chart displaying the middle of all HRV values for male and female Heartify members between the ages of 20 and 65. You can see above that the normal HRV range declines for both men and women as they age. For example, the middle half of 25-year-old males fall roughly from 60-100, while 50-year-olds are around 35-60. Females of the same ages see a similar dip, from about 50-90 to 30-55.
Athletes and sportspersons have a greater HRV than non-athletes, although many people are in great shape and have an HRV below the ideal number.
Athletes and sportspersons have a greater HRV than non-athletes, although many people are in great shape and have an HRV below the ideal number.
What Is a good HRV score?
ResearchGate
Factors influencing heart rate variability (Stefan Sammito and Irina Böckelmann)
Heart International
Influence diagram of physiological and environmental factors affecting heart rate variability: an extended literature overview (Julien Fatisson, Victor Oswald, François Lalonde)
National Library of Medicine
Reference values of heart rate variability from 10-second resting electrocardiograms: the Lifelines Cohort Study (Balewgizie S Tegegne, Tengfei Man, Arie M van Roon, Harold Snieder, Harriëtte Riese)
Research Gate
Influence of Heart Rate, Age, and Gender on Heart Rate Variability in Adolescents and Young Adults (Mario Estévez, Claudia Carricarte Naranjo, Javier Jas Garcia, Evelyn Rodríguez Ríos, Calixto Machado, Julio Montes Brown, Gerry Leisman, Adam Schiavi, Andrés Machado, Claudia Sánchez Luaces, Eduardo Arrufat-Pié,)
factors
As you see, when it comes to HRV, there is no one-size-fits-all. We deal with a very subjective measure. So rather than comparing yourself to others and worrying about whether HRV is normal, it is more practical to follow your trends. And remember to consider all the following factors when interpreting HRV data.
What Factors Affect HRV?
Age
As you age, your HRV score generally decreases due to the natural aging process of the heart muscle. One study of over 150,000 people analyzed men's and women's HRV levels and showed the numbers - around 80 ms for teenagers and 25ms for those over 75 years.
Gender
Changes in hormone levels can import your HRV score. Studies have shown that men have higher HRV scores than women.
As you age, your HRV score generally decreases due to the natural aging process of the heart muscle. One study of over 150,000 people analyzed men's and women's HRV levels and showed the numbers - around 80 ms for teenagers and 25ms for those over 75 years.
Gender
Changes in hormone levels can import your HRV score. Studies have shown that men have higher HRV scores than women.
Physical activity
Regular exercises can improve your HRV score. However, HRV may decline for a few hours after intense exercise, but it should level back out provided you give your body ample time to recover. The key is to find a balance that works for you.
Stress
Managing stress is essential for maintaining a healthy HRV score. It has a significant impact on your HRV score. Chronic stress can lead to long-term decreases in HRV, while acute stress can cause short-term reductions. Managing stress is essential for maintaining a healthy HRV score.
Alcohol consumption
Drinking alcohol has been shown to decrease your HRv score. If you drink alcohol regularly, you may want to consider cutting back or quitting altogether to improve your heart health.
Tobacco use
It is scientifically proven that smoking tobacco decreases HRv scores. If you smoke tobacco, quitting is one of the best things you can do for your heart health.
Regular exercises can improve your HRV score. However, HRV may decline for a few hours after intense exercise, but it should level back out provided you give your body ample time to recover. The key is to find a balance that works for you.
Stress
Managing stress is essential for maintaining a healthy HRV score. It has a significant impact on your HRV score. Chronic stress can lead to long-term decreases in HRV, while acute stress can cause short-term reductions. Managing stress is essential for maintaining a healthy HRV score.
Alcohol consumption
Drinking alcohol has been shown to decrease your HRv score. If you drink alcohol regularly, you may want to consider cutting back or quitting altogether to improve your heart health.
Tobacco use
It is scientifically proven that smoking tobacco decreases HRv scores. If you smoke tobacco, quitting is one of the best things you can do for your heart health.
Climate
Extreme temperature changes can impact your HRV score. To avoid this, dress warmly in cold weather and stay hydrated in hot weather.
Noise
Noise pollution has been linked to decreased HRV scores. To protect your heart health, try to limit your exposure to loud noises as much as possible.
Extreme temperature changes can impact your HRV score. To avoid this, dress warmly in cold weather and stay hydrated in hot weather.
Noise
Noise pollution has been linked to decreased HRV scores. To protect your heart health, try to limit your exposure to loud noises as much as possible.
exceptions
High heart rate variability (HRV) is a good thing—generally. But there are exceptions to every rule, and if your HRV suddenly spikes, it could indicate something is not quite right.
Is a higher HRV always 'better'?
One of the most common causes of a high HRV is overtraining. When you train too hard and too often without adequate recovery, your body never has a chance to repair the damage done by training thoroughly. In the future, you will have various problems, including decreased performance, injuries, and chronic fatigue. Therefore, remember to have at least one resting day a week.
Another common cause of a high HRV is mild sickness. If you are coming down with a cold or the flu, your body will work overtime to fight the infection, followed by increased heart rate and changes in sleep patterns. Pushing yourself too hard when sick can worsen the illness and delay recovery.
Finally, changes in sleep patterns can impact HRV levels. Getting enough quality sleep is crucial for recovery, so make sure you prioritize rest as much as possible during periods of change.
If you typically sleep seven hours per night but start sleeping nine hours each, your body will need time to adjust. The same is true if you have trouble sleeping or experience disruptions in your sleep patterns. Thus, if your HRV starts to climb abnormally high within a day or two, it is crucial to give the body time to recover. Otherwise, be ready for negative results in the long run.
If you typically sleep seven hours per night but start sleeping nine hours each, your body will need time to adjust. The same is true if you have trouble sleeping or experience disruptions in your sleep patterns. Thus, if your HRV starts to climb abnormally high within a day or two, it is crucial to give the body time to recover. Otherwise, be ready for negative results in the long run.
The Heartify Methodology
Science
National Library of Medicine
A review on wearable photoplethysmography sensors and their potential future applications in health care. (Denisse Castaneda, Aibhlin Esparza, Mohammad Ghamari, Cinna Soltanpur, and Homer Nazeran)
Photoplethysmographic Waveform Versus Heart Rate Variability to Identify Low Stress States. Attention Test. (Marıa Dolores Pelaez Coca, Marıa Teresa Lozano Albalate, Alberto Hernando Sanz, Montserrat Aiger Valles, Eduardo Gil)
METHODOLOGY
What is Photoplethysmography (PPG)?
Heartify is a personalized, all-in-one app to monitor your heart health. The App lets you track heart health anytime and anywhere, right from the finger. It detects and analyzes heart rate variability (HRV) and produces a personalized report to provide valuable insights into the current state of wellness.
We use a technique called photoplethysmography, simply PPG, where the camera light illuminates finger skin tissue to measure the volume of blood circulating in your finger. Measurements are taken by illuminating the finger with a light source and noting changes in the intensity of the reflected light. The light scattered back from the tissue varies in intensity according to the blood flow in the tissue. This variation is known as the plethysmographic waveform. The technology can then use the changes in blood flow to calculate heart rate variability and other cardiovascular parameters.
PPG has many advantages, like being non-invasive, portable, and relatively inexpensive. Although some factors can affect the accuracy of measurements (venous congestion, skin moisture, and movement artifacts), it remains a helpful tool for measuring changes in blood flow and other cardiovascular parameters for over 50 years.
PPG has many advantages, like being non-invasive, portable, and relatively inexpensive. Although some factors can affect the accuracy of measurements (venous congestion, skin moisture, and movement artifacts), it remains a helpful tool for measuring changes in blood flow and other cardiovascular parameters for over 50 years.
Measurement
It is important to remember that heart health needs to be taken care of on an ongoing basis; and not something you can think about once and then forget. To ensure you get reliable measurements every time, follow these tips.
How and when to measure HRV?
It is essential to remain in the same position during the measurement and avoid movement to obtain an accurate result. One study compared the heart rate variability of adults in various positions (supine, lying on the right and left side, sitting, standing, and posture with the head tilted up and down). We can see a difference in the results in vertical and horizontal positions. Therefore, better to take measures in a standing position rather than seated or supine.
We recommend taking measurements in the morning at the same time. Research shows that HRV increases at night, giving you the wrong readings. Keep a proper temperature in the room so you stay calm and relaxed.
Exercising, eating, drinking coffee, dancing, etc., will 100% affect HRV. Therefore, we recommend taking baseline readings soon after waking up when your body is still calm and relaxed.
During the daily baseline measurement of HRV, it is widespread for a person to use unnatural breathing patterns. Slow deep breathing activates the parasympathetic nervous system and, as a result, increases heart rate variability. If you want an accurate result, stick to your normal breathing rhythm.
To start a healthier lifestyle and increase your average HRV, you should measure regularly and follow the long-term trend. We suggest doing this twice daily to see how it changes throughout the day.
It is important to remember that various inflammations, food intolerances, and overly active training can affect HRV measurements. When taking an HRV reading, consider any significant lifestyle changes that may have occurred in the past week or so. For example, if you have just started a new exercise routine or changed your diet, these factors could impact your readings.
Disclaimer. The contents are for general information and educational purposes only. It neither provides medical advice nor intends to substitute professional medical opinion on treating, diagnosing, preventing, or alleviating any disease, disorder, or disability. Before undertaking a new healthcare treatment, please consult your doctor about your health condition and/or concerns.