Heart Rate Variability: How It Might Indicate Well
When it comes to your health, it is now easy to measure and track all kinds of information. In the comfort of our homes, we can check our weight, blood pressure, number of steps, calories, heart rate, and blood sugar. Researchers have been exploring another data point called heart rate variability as a possible marker of resilience and behavioral flexibility.
Is My Heart Rate Variability Something That Should Make Me Worry
In general, an abnormal heart rate variability isnt something that will cause a medical emergency, but it can be a sign of current health problems or issues down the road. Its also important to remember that most consumer-level devices that track heart rate variability are not as sensitive as an EKG.
Its important to keep in mind that your heart rhythm is incredibly complex. While you can find devices and apps that track your heart rate variability, a healthcare provider is the most qualified to look at your heart rate and advise you on what you can and should do about it.
Measuring At The Right Time: The Morning Routine
Consider that what we try to measure is parasympathetic activity, so the branch of the autonomic nervous system in charge of rest, recovery and relaxation. The ANS is affected by pretty much anything , hence measuring throughout the day or at random time points during the night typically results in capturing transient stressors and telling us very little about our chronic physiological state.
Even when beat to beat data can be acquired with high accuracy in free living, one single measurement in a well known context is more valuable than recording more data at random times during the day or night.
If you are interested in measuring underlying or chronic physiological stress to potentially make adjustments to your lifestyle or training plan, then you would end up missing that information or confounding it with whatever is happening in your day.
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Assessment In Clinical And Optimal Performance Interventions
The selection of HRV time-domain, frequency-domain, and non-linear measurements and norms to assess progress in clinical and optimal performance interventions should be informed by peer-reviewed studies. Professionals training specialized populations might supplement published norms for the general population with values from their own clients. The rigorous data reporting guidelines proposed by Laborde et al. could guide their efforts to publish their norms to remedy gaps in the literature. The metrics most strongly correlated with clinical improvement and athlete performance gains in these reports could be incorporated in pretreatment/posttreatment, within-session, and across-session assessment. While a full treatment of HRV variables in relation to the HRV biofeedback intervention is beyond the scope of this article, we will briefly touch on the issues that seem to us to be the key ones .
In addition to the primary literature, the Association for Applied Psychophysiology and Biofeedback has published two references that identify metrics associated with clinical and optimal performance outcomes, Evidence-Based Practice in Biofeedback and Neurofeedback and Foundations of Heart Rate Variability Biofeedback: A Book of Readings . Further, readers might consult Gevirtz, Lehrer, and Schwartzs excellent chapter on Cardiorespiratory Biofeedback in Schwartz and Andrasiks Biofeedback: A Practitioners Guide .
Evidence For Hrvs Influence On Cardiac Issues & General Health Outcomes
Like smoking, diabetes and elevated lipids, low HRV is a risk factor for mortality in all patients. For several decades it has been known that low heart rate variability predicts sudden cardiac death from arrhythmias after a heart attack and that it also predicts post-heart attack survival .
Low HRV is also associated with depression, anxiety disorders, and post-traumatic stress disorder . Low HRV is an index of compromised health overall, but especially important in coronary artery disease. Thus, for patients with a history of cardiac issues or risks, increasing heart rate variability is highly recommended.
As far back as 1996, it was known that reduced heart rate variability predicted increased risk for subsequent cardiac events such as coronary heart disease, congestive heart failure, and myocardial infarction in both men and women who had no clinical symptoms of heart disease . Previous research has already shown that lowered Heart Rate Variability predicted increased risk for all-cause mortality.
In 2013, a European study showed that low HRV is associated with an increased risk of a first cardiovascular event in populations without known cardiovascular disease . On the positive side, increasing HRV may result in a lower risk of fatal or non-fatal cardiovascular disease.
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Causes Of High Heart Rate Variability
A high HRV is known to be a sign of a healthy heart. Most of the studies have found that a higher HRV is associated with lowered morbidity and mortality and enhanced psychological well-being and good quality of life.
Often, the most common cause of high heart rate variability is due to the continuous low-grade stressors. These stressors in the short term lead to a higher HRV as the body is continuously making an effort to recover from the situation.
Is Heart Rate Variability Like An Arrhythmia
Heart rate variability is a normal occurrence, and it isnt an arrhythmia on its own.
The normal beating of your heart is called sinus rhythm. When your heart is beating normally but the variability between heartbeats is greater than 0.12 seconds, this is called sinus arrhythmia. Heart rate variability can sometimes meet the criteria for sinus arrhythmia.
Sinus arrhythmia is usually due to breathing , which is part of a normal reflex of your heart and circulatory system. However, when sinus arrhythmia isnt caused by breathing, it may be a sign of another heart problem that does need assessment by a healthcare provider.
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Understanding Normal Heart Rate Variability
Heart rate variability , which is regulated by your autonomic nervous system, is very useful for evaluating physical fitness and your bodys readiness to perform. Measured in milliseconds , HRV is literally the difference in time between beats of your heart.
If heart rate variability is something youre not already familiar with, check out our Ultimate Guide to HRV to better understand what it is and why its so meaningful.
Broadly speaking, higher HRV is usually an indication of better fitness. However, one of the most important things to realize with heart rate variability is that it is an extremely individualized metric that often differs significantly from one person to another. It can also fluctuate considerably on a day-to-day basis .
Heart Rate Variability Monitor Firstbeat Bodyguard 3
With Firstbeat Bodyguard 3 sensors you can record RR-intervals, ECG and/or 3D acceleration based on your requirements. The sensor uses clinically approved medical electrodes to monitor ECG-based beat-to-beat heart rate data . This is the gold standard for heart rate variability monitoring used in clinical settings.
Firstbeat Bodyguard 3 HRV Monitoring Device
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What Do Hrv Numbers Mean
Heart rate variability is the difference in time between the beats of your heart, measured in milliseconds .
For the most part, younger people have higher HRV than older people, and males may have slightly higher HRV than females. Additionally, elite athletes tend to have greater heart rate variability than non-athletes. However, what represents a healthy HRV varies for everybody. There are many exceptionally fit people who have heart rate variability that is lower than the norm.
Below is a graphic that shows the average range of heart rate variability by age, from 20-65.
How Can You Improve Your Hrv
Whoop provides an excellent guide on HRV, calling out the six specific things one can do to improve Heart Rate Variability.
Please dont overdo it and push too hard for too many days without allowing your body to recover. One training aspect that seems to improve HRV, according to many users, is sprint training.
Try implementing some form of sprint training/conditioning .
You dont need to do long sprint sessions, but you need to keep them hard and fast.
A good example sprint session could be 4x100yd sprints w/ 45seconds rest . The sprints need to be fast!
The better hydrated you are, the easier it is for your blood to circulate and deliver oxygen and nutrients to your body.
Aiming to drink close to one ounce of water per pound of body weight each day is a good goal.
One night of drinking may negatively affect your HRV for up to five days.
Steady Healthy Diet.
Poor nutrition adversely affects HRV, as does eating at unexpected times.
Its not just the amount of sleep you get that matters but also your sleep quality and consistent sleep.
Going to bed and waking up at similar times each day is beneficial.
In general, trying to get your body on a consistent schedule is helpful.
Your body does things more efficiently when it knows whats coming.
Practice Resonant Breathing at least twice a day.
Slow your breathing rate to around six deep breaths per minute for you to gain control over your breathing.
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What Do Hrv Variations Mean
HRV variations are a sign that your body is trying to return to its normal state .
High variation usually means that your body is adapting to stress. This can come from training or other stressors. If your variation is high and youre not training that usually means that youre stressed, either physically, chemically, or emotionally.
Having a low HRV means that your body is at or near homeostasis. If your daily readings are at or near your baseline levels, your body isnt getting enough stress or stimulus to adapt.
Experiment with different exercises to learn what lowers your HRV and what activities help raise your HRV. If the variation is high from day-to-day absent training, youre either stressed or youre not measuring consistently.
Record and compare your variations with how you feel. Do they match? If your HRV is low do you feel stressed? Use both methods to get a full view of your health.
Mistake 7 Paced Breathing During Readiness Readings
Using paced or guided breathing during an HRV measurement is not necessarily a mistake in itself. Paced breathing becomes a mistake when unnatural breathing patterns are used during a readiness or daily baseline HRV measurement.
It is well established that certain breathing patterns, especially slow, deep breathing, influences Vagus Nerve and Parasympathetic Nervous System activation and increases Heart Rate Variability. If you breathe at artificially slow breathing rates during a readiness or daily HRV reading, it can artificially skew the reading results to show your HRV to be higher than it actually would be in your natural state.
Because of this, paced breathing during a readiness or daily measurement is not recommended unless done at an individuals normal breathing pace. An average adults natural breathing rate usually falls within 12-18 breaths per minute, however more aerobically fit individuals may have slower natural breathing rates. The best case for following a breathing pacer during a morning or daily readiness measurement is to help avoid fidgeting, distracting thoughts, or to help stay relaxed.
Note: Paced or guided breathing is perfectly acceptable and even encouraged when used for live HRV biofeedback training or other HRV testing.
If you breathe at artificially slow breathing rates during a readiness or daily HRV reading, it can artificially skew the reading results to show your HRV to be higher than it actually would be in your natural state.
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Health And Other Applications Of Hrv
Beyond using heart rate variability as a fitness metric, it also has many applications when it comes to our overall health and well being. Tracking your HRV can help you gain a better understanding of:
For example, if your daily routine is unchanged but your HRV drops, it may be an indicator of increased stress or oncoming illness. Or, if youd like to see the effect a new diet has on your body, the impact will be noticeable in your heart rate variability.
What About Using Data Points Automatically Collected By The Apple Watch During The Night
While during the night we might think that being unconscious its an ideal moment to collect good data, this is not really the case unless we use the whole night of data . This is the case mostly because of two aspects:
- The circadian rhythm: HRV tends to increase during the night, as you rest . If we use a data point collected at 1am one day, and at 4am another day, then we might have large variability between the scores simply because they are far apart. At that point, it is much better to take a morning measurement when you wake up, which is most likely happening every day in a narrower range.
- Sleep stages: HRV changes between different sleep stages . It follows that of course if the sleep stage affects HRV, the HRV reported in the morning is also affected by when during the night it was measured.
Here is an example:
We can see quite clearly that the two averages are different. However, due to the circadian component andsleep stages , it would be foolish to pick a single data point and use those as something representative of the physiological stress level for this person.
Note that these problems are automatically removed by a morning measurement: you are awake and no circadian rhythm . And indeed for the case above, we have the following:
- Morning HRV in the high stress day: 35 ms
- Morning HRV in the low stress day: 58 ms
HRV is highly influenced by acute stressors , hence the importance of the morning routine, measuring as soon as you wake up .
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When Should Hrv Be Measured
Harvard Health recommends checking your HRV in the morning after waking up. To do so, they suggest buying a chest strap heart monitor and using an app to analyze your data.
Try to measure HRV while youre at rest, not after exercising or any other activity that can significantly affect your baseline HRV reading. Do this a few times a week and note the results so you can track any changes.
How Hrv Is Related To Fitness
Your heart rate variability doesnt directly reflect your level of fitness. In other words, just because someone has a higher HRV than you, doesnt make them fitter than you. I know plenty of people who have a higher HRV than I have but theyre not fitter than I am.
However, if your HRV is low while youre not actively engaged in a sympathetic activity , its a sign that your body is working hard for some other reason, such as fatigue, illness, stress or overtraining. If thats the case, youll likely have fewer resources at your disposal to crush your next workout.
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Explaining Hrv Numbers And Age Whats Normal Good And Bad
HRV numbers decline exponentially with age but are higher in athletes and especially masters athletes, who can have HRV numbers comparable to active 25-year-olds.
Over the 10+ years Ive been working with Heart Rate Variability , Ive lost count of the number of times Ive been asked whether an ithlete users HRV number is good, and if not, what does good look like.
What Is The Average Hrv For My Age Sex And Fitness
With that background set, now lets get to the numbers. The most comprehensive survey of the general population that Im aware of comes from a 2019 study of over 150,000 people in the Netherlands and includes both HRV and resting heart rate . The charts below show the HRV numbers themselves, which decline in an exponential manner from around 80milliseconds for teenagers to 25ms for those over 75 years.
The equivalent chart using the log scale is shown below you can see there is a more linear decrease with age up to the late 60s, after which HRV stabilizes in later life. This linear behavior, when log-transformed, is typical also of changes experienced by an individual on a day-to-day basis due to changes created by training and lifestyle.
Both charts show that HRV numbers for men and women are pretty much equivalent.
So, if these are representative averages for a broad population, what about sportsmen and women? A study in 2012 enrolled 200 subjects aged 18-24 who either took part in competitive sports or who had an active lifestyle but were not competitive.
The chart below shows comparable numbers between active men and women to the general population as you would expect, whereas those for sportsmen and women are considerably higher .
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What Is A Good Heart Rate Variability While Sleeping
Because heart rate variability is specific to each individual, giving a specific number of recommended beats per minute is difficult. Generally, your heart rate while sleeping should be 20 to 30 percent below your resting heart rate during the day. As you measure your HRV over time, you should get an idea of what your baseline HRV is and whats healthy for you.
However, as a general rule of thumb, your sleeping HRV score should be lower than your wakeful HRV score. What if the numbers are similar or your sleeping HRV score is higher than your daytime HRV score? You may want to speak with your doctor about possible mental or physiological factors affecting your HRV, such as anxiety.
How Can You Track Your Hrv
According to Dr. Horwich, the most accurate way to track heart rate variability is by getting a continuous electrocardiogram, EKG, which records the electrical signal from your heartbeats. To record the heart rhythm over a period of time, the cardiologist will have the person wear something called a Holter monitor or patch, which captures an EKG even while the person is on the go.
What about smartwatches? Dr. Horwich says the HRV from smartwatches is based on the heartbeats it detects from your wrist pulse, so it may not be as accurate as the reading you get from an EKG that’s reading the heartbeats from your chest.
This doesn’t mean you need to discredit that number though, because your smart tracker’s HRV can still be something you speak to your doctor about if you’ve noticed a stark change over time. But as you track it on your device, the main thing to remember is not to stress over it, because again, it may not be 100 percent accurate . So you can take note of it, acknowledge it, bring it up to your doctorâbut don’t panic over it.
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