If you sport a fitness tracker like festival-goers sport metallic hip packs during Coachella, chances are you’ve heard of heart rate variability (HRV). However, unless you’re also a cardiologist or professional athlete, chances are you don’t know what the heck it actually is.
But considering heart disease is the leading cause of death among women, you should know as much as possible about your ticker and how to keep it healthy—including what this number means for your health.
What Is Heart Rate Variability?
Heart rate—a measure of how many times your heart beats per minute—is commonly used to measure your cardiovascular exertion.
“Heart rate variability looks at how much time, in milliseconds, passes between those beats,” says Joshua Scott, M.D., a primary care sports medicine physician at Cedars-Sinai Kerlan-Jobe Institute in Los Angeles, CA. “It measures the variation in the amount of time between those beats—usually aggregated over days, weeks, and months.”
Interestingly enough, even if your heart rate is the same in two separate minutes (so the same number of heart beats per minute), those beats may not be spaced out in the same way.
And, unlike your resting heart rate (where a lower number is generally better), you want your heart rate variability to be high, explains cardiologist Mark Menolascino M.D., author of Heart Solution for Women. “Your HRV should be high because, in healthy individuals, the variation of heartbeats is chaotic. The more fixed the time is between beats, the more prone to disease you are.” That’s because the lower your HRV, the less adaptable your heart is and the worse your autonomic nervous system is functioning—but more on this below.
Think about a tennis player at the start of a volley: “They’re crouched like a tiger, ready to move side to side,” says Dr. Menolascino. “They’re dynamic, they can adapt to where the ball goes. You want your heart to be similarly adaptable.” A high variability indicates that your body can adapt to a given situation in a moment’s notice, he explains.
Essentially, heart rate variability measures how quickly your body can go from fight-or-flight to rest-and-digest, explains Richard Firshein, D.O., founder of Firshein Center Integrative Medicine in New York City.
This ability is controlled by something called the autonomic nervous system, which includes the sympathetic nervous system (fight or flight) and the parasympathetic nervous system (reset and digest), explains Dr. Menolascino.
“A elevated HRV suggests that you can alternate swiftly between these two systems,” he states. A decreased HRV suggests that there’s an inequity and either your instinctual reaction to either flee or fight is activated excessively (also known as being stressed as heck), or that it’s not functioning optimally. (See Additional Information: The Harmful Impact of Stress on American Women).”
One significant detail: Investigation demonstrates that arrhythmia—an ailment when your heartbeat becomes excessively fast, excessively slow, or has irregular beats—can lead to short-term HRV changes. However, authentic heart rate variability is quantified over weeks and months. Consequently, an extremely high HRV (read: very diverse) does not indicate something negative. In reality, the opposite holds true. A lower HRV is linked to high-risk arrhythmia, while a high HRV is actually regarded as “cardio protective,” signifying that it helps protect the heart against potential arrhythmias.
How to Measure Your Heart Rate Variability
The simplest—and, to be honest, the only truly accessible—way to measure your heart rate variability is to wear a heart rate monitor or activity tracker. If you wear an Apple Watch, it will automatically record an average HRV reading in the Health app. Similarly, Garmin, FitBit, or Whoop all measure your HRV and utilize it to provide you with information about your body’s stress levels, how recovered you are, and how much sleep you require.
“The fact is, there are no strong research studies in this specific area of smartwatches, so, consumers should exercise caution regarding their accuracy,” says Natasha Bhuyan, M.D., a One Medical Provider in Phoenix, AZ. That being said, one (extremely small) 2018 study found that HRV data from the Apple Watch is fairly precise. “I wouldn’t solely rely on this,” however, states Dr. Scott.
Other alternatives for measuring your heart rate variability comprise of: undergoing an electrocardiogram (ECG or EKG), which is typically conducted in a doctor’s office and measures the electrical activity of your heart; a photoplethysmography (PPG), which employs infrared light to identify subtle variations in your heartbeats and the interval between those beats, but is generally only performed at a hospital; and pacemakers or defibrillators, which are essentially for individuals who already have or had heart disease, in order to automatically measure heart rate variability and monitor the disease. Nonetheless, since most of these necessitate visiting the doctor, they are not exactly convenient methods to keep track of your HRV, making a fitness tracker your best option.
Positive vs. Negative Heart Rate Variability
Unlike heart rate, which can be measured and immediately classified as “normal”, “low”, or “high”, heart rate variability is essentially significant in terms of how it develops over time. (
Rather, each individual possesses a distinct HRV that is customary for them, according to Froerer. It can be influenced by a broad range of factors such as age, hormones, level of physical activity, and gender.
For that reason, comparing heart rate variability among different individuals doesn’t hold much significance, states Kiah Connolly, M.D., an emergency medicine physician certified by the board at Kaiser Permanente and the health director at Trifecta, a nutrition company. (So, no, there’s no ideal HRV number.) “It carries more meaning if it’s compared within the same individual over time.” This is why experts suggest that while an ECG is presently the most accurate technology for measuring HRV in the moment, a fitness tracker that regularly collects data and can display your HRV over weeks and months is optimal.
Heart Rate Variability and Your Well-being
Heart rate variability is a fantastic gauge of overall well-being and physical fitness, as stated by Froerer. Although your personal HRV changes are of utmost importance to monitor, generally speaking, a “high HRV is linked to enhanced cognitive function, quicker recovery ability, and, in the long run, can serve as an excellent indicator of improved health and physical fitness,” she explains. On the other hand, a low HRV is associated with health conditions such as depression, diabetes, high blood pressure, and an increased risk of coronary heart disease, she states.
Here’s the catch: While good HRV has been associated with good health, research hasn’t examined sophisticated HRV patterns extensively enough to establish definitive cause-and-effect relationships between HRV and your well-being, according to Dr. Menolascino.
Nevertheless, heart rate variability is, at the very least, a reliable indicator of your stress level and how effectively your body is coping with that stress. “That stress could be physical (such as helping a friend move or completing a strenuous workout) or chemical (like elevated cortisol levels due to a boss yelling at you or an argument with a partner),” Froerer explains. In fact, HRV’s connection to physical stress is why it is considered a valuable training tool by athletes and coaches.
Utilizing Heart Rate Variability for Insights into Fitness Performance
It is common for athletes to train specifically within their heart rate zone. “Heart rate variability provides a more in-depth understanding of that training,” states Dr. Menolascino.
As a general rule, “Less trained individuals will exhibit lower HRV compared to those who are highly trained and engage in regular exercise,” according to Dr. Scott.
However, HRV can also be used to determine if someone is overtraining. “HRV can serve as an indicator of one’s fatigue level and ability to recover,” explains Froerer. “If you wake up with a low HRV, it indicates that your body is experiencing excessive stress, and you should lower the intensity of your exercise for that day.” Conversely, if you wake up with a high HRV, it means your body feels good and is prepared for rigorous activity.
That’s why some athletes and coaches utilize HRV as one of several indicators of an individual’s adaptation to a training regimen and the physiological demands placed on them. “The majority of professional and elite sports teams utilize HRV, and even some collegiate teams,” says Jennifer Novak C.S.C.S.
proprietor of PEAK Symmetry Performance Strategies in Atlanta. “Mentors are able to employ athletes’ information to adapt the intensity of workouts or introduce methods for rejuvenation to endorse equilibrium in the autonomic nervous system.
But, you don’t need to be elite to utilize HRV in your training. If you’re preparing for a race, attempting to succeed in the CrossFit Open, or just beginning to go to the gym regularly, monitoring your HRV may be advantageous in helping you determine when you’re pushing yourself too hard, says Froerer.
Enhancing Your Heart Rate Variability
Anything deemed beneficial for your overall well-being—managing your stress levels, consuming nutritious meals, getting a full eight hours of sleep each night, and engaging in physical activity—is beneficial for your heart rate variability, according to Dr. Menolascino.
On the other hand, leading a sedentary lifestyle, experiencing a lack of sleep, indulging in excessive alcohol or tobacco use, enduring prolonged periods of heightened stress, having subpar nutritional habits, or gaining weight/becoming obese can all result in a declining HRV, as mentioned by Dr. Menolascino.
Is it necessary to monitor your heart rate variability? No, not necessarily. “It’s valuable information to have, but if you’re already exercising and prioritizing your health in other ways, chances are your HRV is above average,” says Sanjiv Patel, M.D., a cardiologist at MemorialCare Heart & Vascular Institute at Orange Coast Medical Center in Fountain Valley, CA.
However, it may prove beneficial if you’re motivated by data. For example, “having the data easily accessible can serve as a helpful reminder for CrossFit athletes to avoid overtraining, for parents to remain calm around their children, or for CEOs in high-pressure situations to practice deep breathing,” says Dr. Menolascino.
In essence, heart rate variability is just one more useful tool for assessing your well-being, and if you’re already using a HRV-capable tracker, it’s worth examining your readings. If your HRV starts to decline, it may be advisable to consult a medical professional, but if your HRV begins to improve, it indicates that you’re leading a healthy lifestyle.