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What Is Heart Rate Variability (HRV)?

HRV is defined as the variation in time between heartbeats. Your heart rate goes up when you exercise, or in response to stressful situations, but down when you’re trying to relax and go to sleep for the night. The variation between your heart rate can be considerable throughout the day. And that’s a good thing! Your heart is not in lock-step like a metronome: so your HRV being on the higher side means your heart is adapting well to changing conditions, from exercise, to stress, to relaxation, to sleep, from a slower to a faster heart rate (HR), or vice versa.

Stimulation of your heart rate and breathing are controlled by the sympathetic nervous system, which is triggered by stress. (The hormone cortisol, for example, is produced by the adrenal glands in response to stress.) The parasympathetic nervous system has the opposite effect: slowing down heart rate and respiration to allow you to “rest and digest,” while you relax and go to sleep.

Repeated or prolonged exposure to stress causes overactivation of the sympathetic nervous system. This results in secretion of another stress hormone, adrenaline (epinephrine) by the adrenals) and lowered HRV.

Note that lowered HRV means rapid heartbeat. We know that over the long term, a persistently high HR is not healthy. So by trying to raise your HRV, you lower your HR. Monitoring your personal HRV with our B100 app is a great way to start!

To get started simply join The B100 Young At Heart Club

What Are The Benefits Of Knowing My HRV

  • Your HRV is an independent predictor of cardiac risk. Therefore, knowing you have a low HRV may enable you or your doctor to discover other underlying heart problems. (However, there may or may not be any further issues.) Either way, you can begin mitigating your risk.
  • Identify whether your nervous system, is balanced and functioning optimally
  • Provides insights into your levels of stress and your ability to handle or recover from additional stress
  • Higher HRV independently associated with better overall psychological well being. Some studies have even shown that having a higher HRV even improves your executive functioning. You may be able to use biofeedback to help raise HRV.


At Risk Factor For Heart Attack

While you might think that a steady and constant heartbeat is desirable, it actually isn’t healthy: That is because it shows an inability to adapt to changing conditions. Very often, people with low HRV actually have a high resting heart rate, so they do not have much space or time between beats to register changes in rhythm.

In 1987, Robert Kleiger and colleagues published a landmark paper demonstrating that patients with a low HRV were five times more likely to die following a severe heart attack than those patients who did not have low HRV.



A moderate amount of variability in your heart rate (HRV) is actually a good thing, because it means you adapt well to changing life conditions such as stress. The word for this is resilience–and it’s what we should all strive for! It means you roll with the punches. Having an optimal HRV brings with it significant benefits–not just in terms of cardiac health, but for overall well-being. As you become more fit, your HRV will often increase, but will stay within reasonable limits. What these are is not something we can advise.


Not Always Good - Caution

If you suddenly start having extremely high HRV levels, this is not always a good thing, despite what some fitness enthusiasts might tell you. It could be pathological, meaning there could be some sort of conduction problem going on in your heart. Atrial fibrillation (“A-fib”) is one of the most common types of arrhythmias. This is really something to consider if you are a certain age (have an AARP card), or have other cardiac risk factors, and your HRV suddenly skyrockets, see your cardiologist or go to the ER right away.

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