Guide to HRV: How to Check Heart Rate Variability

Heart rate variability (HRV) refers to the frequency of interbeat intervals (RR intervals) of your cardiovascular system. While it might seem as though a healthy heart beats in even syncopation, minor fluctuations between each beat are preferable. The modulation between each beat of the heart is often measured in metrics of milliseconds, but it has a real-time and extensive effect on your health holistically.

Your heart rate variability is controlled by your autonomic nervous system, which is split into three branches: the parasympathetic nervous system, the sympathetic nervous system, and the enteric nervous system. Parasympathetic activity is almost always happening in the background (resting, digesting, various organ functions, etc.), whereas sympathetic activity indicates a raised heart rate brought on by physical activity or an activation of your body’s fight or flight response to stressors. The enteric system controls the function of the pancreas, gallbladder, and gastrointestinal tract.

When the crossover between the competing parasympathetic and sympathetic nervous systems are working together optimally, you have a higher HRV; when one is outcompeting or overcompensating for the other, you’ll have a lower HRV. So a high frequency of variation in your heart rate (high HRV) indicates a state of overall health and well-being, while a low frequency of variation (low HRV) indicates it’s time to take a look at and address your stress levels and any other health risk factors.

Fit, healthy subjects almost invariably have a high level of heart rate variation. Eating well lowers your risk for things like high blood pressure, heart disease, hypertension, and diabetes mellitus, but it also correlates to a healthy HRV. Similarly, regular exercise helps balance out your autonomic nervous system by allowing your sympathetic nervous system to respond to stress more effectively in a controlled manner. It also keeps your baroreflex (the mechanism for maintaining ideal blood pressure) functioning at optimum levels.

HRV analysis is key to discovering whether your heart rate is varying optimally. These HRV measurements and metrics help doctors determine how your HRV is doing:

1. 1. Time domain: Time domain HRV analyses proceed by counting the intervals themselves between heartbeats. SDNN (standard deviation of normal-to-normal) is one of the most commonly used time domain measurements and is generally tracked for around 24 hours. RMSSD (root mean square of successive differences) is another of the most prominent.
2. 2. Frequency domain: Frequency domain analysis works similarly to time domain practices, but the emphasis is put on comparing the intervals to pre-assigned frequency bands rather than just counting the intervals’ duration outright.
3. 3. Nonlinear: Sometimes, cardiologists won’t even focus on the linearity of one beat to the next when it comes to heart rate variability. Nonlinear methods are available as well for when doctors think a more unorthodox approach is necessary to see what’s going on in your cardiovascular system.

Checking your heart rate variability helps you stay on top of your health as a whole. Here are three of the top reasons to check how yours is doing:

1. 1. Prevent illness. Discovering you have a low HRV points to the possibility of risk factors for cardiovascular disease. You’ll be able to begin working to prevent the potential of myocardial infarction, ventricular tachycardia, congestive heart failure, and the like if you discover early on that your HRV isn’t at an optimal, high-functioning baseline.
2. 2. Increase fitness. Your HRV is a signal as to how your fitness is doing overall. If your resting heart rate is at a high frequency of variability, it’s a sign you’re likely in an ideal spot for exercise, eating well, and health overall. If it’s lower in frequency, you can take it as a motivator to begin improving your fitness holistically as well.
3. 3. Calibrate your workouts. If you’re an otherwise healthy individual but discover you have a lower HRV after working out specifically, it could be a predictor of overtraining. You can take that as a sign that you need to ease up on your exercise, as you’re activating the sympathetic nervous system’s fight or flight response too strongly.

Checking your HRV doesn’t need to be difficult. Here are three ways you can get the HRV data you need:

1. 1. Get an electrocardiogram (ECG) test done. An electrocardiogram (ECG) test is a procedure done by a cardiologist that will, among other things, use electrophysiology (a test that studies the electrical properties of your biological cells and tissues) to indicate what your heart rate variability is. This test will give you a lot of peace of mind about your heart’s health, as well as suggestions for how to improve its well-being.
2. 2. Utilize a personal chest strap monitor. Purchasing your own wearable heart rate monitor can spare you a trip to the doctor. Still, you should always consult professionals, especially if you see something concerning, as it could be totally benign. For instance, respiratory sinus arrhythmia (irregular rhythm)—caused by the parasympathetic vagal tone (an internal process related to the vagus nerve) and your natural breathing cycle—may cause your heart to beat inconsistently, but it’s not a sign of ill health at all.
3. 3. Sync up with an app. In today’s technologically savvy culture, you can sync up a personal heart rate monitor with a variety of apps that will help you interpret HRV data. Find the right software for you, and you’ll be able to monitor your heart’s health on a regular basis.

Improving your HRV will improve your health in totality. Here are four tips to doing so:

1. 1. Go to your doctor. Unless you own your own heart rate monitor and know how to interpret HRV data, heading to a doctor is still the best way to get an idea of how your HRV is doing and how you can improve it. Going to a doctor that specializes in cardiology can help especially.
2. 2. Reduce stress. Stress is one of the main causes of a low frequency HRV, as well as broader health issues. Alongside eating well and exercising, sleep and mindfulness are both key elements to regulating stress. Maintaining a solid circadian rhythm for sleep will do wonders. Meditation—due to its stimulation of the relaxing vagus nerve through long, deep breaths and overall calming properties—can also help you keep stress in check.
3. 3. Cut out alcohol and unhealthy food. Both alcohol and unhealthy foods add stress to your organs, as they need to work overtime to process them. If you ditch the booze and begin eating well, you may see a positive change in your HRV.
4. 4. Exercise more. Regular exercise is key to health on a holistic basis, so it’s no surprise it also will help your HRV reach a greater degree of wellness. Regular moderate and occasionally vigorous exercise is recommended to keep your autonomic nervous system in check.

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