Heart rate variability (HRV) is a metric that measures the slight fluctuations in time between heartbeats. It can be monitored using a wearable device like a Whoop Band, Oura Ring, or HeartMath.
Your heart beats at a specific rate at all times. That rate changes depending on what you're doing at the time. Slower heart rates happen when you're resting or relaxed, and faster rates happen when you're active, stressed or when you’re in danger. There is variability in your heart rate based on the needs of your body and your respiratory patterns.
Whether you’re awake or asleep, calm or stressed, your heart has to be able to react to changes in your life and surroundings. But it doesn’t know when to react on its own, so it relies on another body system for help.
Parasympathetic vs sympathetic branches and heart rate variability
Your brain and nervous system support your heart. Your senses — sight, sound, smell, taste and touch — feed information to your brain about everything around you. Your brain has a direct line to your heart, telling your heart when it needs to speed up and work harder.
This direct line to your heart is your autonomic (pronounced “auto-nom-ick”) nervous system. This is a part of your brain and a set of nerves that operate without you thinking of them, even when you’re asleep. It’s divided into two main parts: your sympathetic nervous system and your parasympathetic nervous system.
Sympathetic. This is where your “fight-or-flight” response comes from. It manages increases in heart rate and blood pressure in emergency situations.
Parasympathetic. This helps balance out the sympathetic nervous system and controls the natural relaxation response, especially after you’ve been in fight-or-flight mode. It controls slowing your heart rate and blood pressure, among other things, especially when you’re taking it easy.
Here’s an example of how these two parts of your nervous system work together: If you think you’re in danger, you get scared or startled, or if you’re anxious about something, your sympathetic nervous system kicks in and starts the fight-or-flight response. Your body releases adrenaline so you can react faster. Your heart rate goes up, just in case your muscles need more blood and oxygen because of physical activity. Once the situation that put you into fight-or-flight mode is over, your parasympathetic nervous system takes the lead. It tells your heart rate to slow back down and lowers your blood pressure. It also tells various systems of your body to relax or go back to how they normally work.
Why is heart rate variability a good thing?
Your body has many systems and features that let it adapt to where you are and what you’re doing. Your heart’s variability reflects how adaptable your body can be. If your heart rate is highly variable, this is usually evidence that your body can adapt to many kinds of changes. People with high heart rate variability are usually less stressed and happier.
In general, low heart rate variability is considered a sign of current or future health problems because it shows your body is less resilient and struggles to handle changing situations. It's also more common in people who have higher resting heart rates. That’s because when your heart is beating faster, there’s less time between beats, reducing the opportunity for variability. This is often the case with conditions like diabetes, high blood pressure, heart arrhythmia, asthma, anxiety and depression.
How is heart rate variability measured?
The variances in your heart rate are very small, so it takes specialised equipment or devices to detect them. Modern technology has reached a point where non-medical devices that can track heart rate variability are affordable and easy to find (Whoop Band, Oura Ring, HeartMath, to name a few)
In a medical setting, an electrocardiogram machine (also called an EKG) is usually used to detect heart rate variability. This device, which measures the electrical activity of your heart using sensors attached to the skin of your chest, is highly accurate. Healthcare providers can also send you home wearing a monitor that tracks heart rate variability continuously for longer periods of time. The length of time that your heart rate variability is monitored can be anywhere from a few minutes to 24 hours. Longer monitoring times tend to give the best data.
Outside of a medical setting, there are several devices commonly used by athletes, especially runners. These often consist of a device attached to a band that wraps around your chest. Some look like pulse oximeters (devices that attach to a finger and measure your pulse and blood oxygen level) but are more sensitive and accurate.
Can I improve my heart rate variability?
There are a few different ways that you can improve your heart rate variability. Some involve improving your physical condition. Others include taking care of your mental health. Here are a few general things you can do:
Take care of your body. Regular exercise and a healthy diet improve your overall health, especially the condition of your heart.
Take care of your mind. Your mental health is a vital part of your heart rate variability. Reducing and managing your stress level can improve your heart rate variability. If you have mental health concerns like anxiety or depression, managing these can make a difference.
One method to help improve heart rate variability is called “biofeedback training.” By controlling your breathing through biofeedback training, you can improve your heart rate variability. There’s also evidence to show that biofeedback training can help improve your levels of stress and anxiety. HeartMath is an example of this
Is my heart rate variability something that should make me worry?
In general, an abnormal heart rate variability isn’t something that will cause a medical emergency, but it can be a sign of current health problems or issues down the road. It’s also important to remember that most consumer-level devices that track heart rate variability are not as sensitive as an EKG it's important to keep in mind that your heart rhythm is incredibly complex. While 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.
Tracking & monitoring your HRV can help with:
Stress - HRV can indicate stress levels by showing imbalances in the autonomic nervous system. However, HRV doesn't always correlate with actual stress levels, so it's not always reliable.
Sleep - Tracking HRV can help you see how sleep affects your health.
Lifestyle - HRV can provide feedback on your lifestyle habits and help you plan workouts. For example, you might notice a connection between HRV changes and incorporating more physical activity, meditation, mindfulness, or good sleep hygiene into your life.
Health concerns - HRV can help predict larger health concerns, illness, injury, and mental or emotional dys-regulations. For example, HRV can indicate current or future health problems, including heart conditions and mental health issues like anxiety and depression. It can also help rule out pathological conditions like hypertension and diabetes.
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