Your heart rate is the number of times your heart beats in a minute. This is a common metric used to measure physical fitness, with a lower heart rate generally being a sign of good fitness. Heart rate variability (HRV) refers to the variation in time between each heartbeat. This is also a useful indicator of your well-being. Here, we’ll explore the meaning of HRV, what influences heart rate variability and how you can improve your cardiovascular health.
What Is Heart Rate Variability (HRV)?
HRV is a measure of the variation in the time between consecutive heartbeats, measured in milliseconds. Even normal, healthy hearts don’t keep time like a metronome. Rather, there’s some natural variation in a person’s heart rate. Being aware of that variability can help you identify whether you’re stressed, burned out, over-training or otherwise in need of rest.
Measurement and Significance of HRV
Measuring your heart rate variability can be a useful way of benchmarking your stress levels and emotional health. If you’re an athlete, tracking your heart rate variability can help you plan your workouts so your most intense training days are when your HRV is high and your rest days occur when your HRV is low.
There are several ways of testing your heart rate variability, including:
- Phone apps. Free phone apps that use your phone’s camera to measure your heart rate and HRV can serve as a starting point for people who are curious about their heart rate variability but aren’t able to invest in a fitness tracker. Taking readings in this way can be awkward and not as accurate as measurements taken with a dedicated device, but they can give you a general idea of your well-being.
- Smartwatches and fitness trackers. Many modern smartwatches offer heart rate monitoring features. Devices such as Fitbits and Apple Watches measure your heart rate through the skin on your wrist. An app on your phone can calculate your HRV based on that data. Wrist-worn devices aren’t particularly accurate, so they can’t be used as a diagnostic tool, but they’re good enough for tracking general trends.
- Chest strap heart rate monitors. Chest strap devices are popular with competitive athletes because they’re both unobtrusive and more accurate than wrist-worn devices. If you’re a consumer looking to monitor your HRV for personal use, a chest strap heart rate monitor is probably the most accurate option.
- Holter monitors and EKGs. Physicians use a portable device known as a Holter monitor to track heart activity and can perform EKG tests in their offices. These tests are the most accurate option but require specialized equipment the average consumer wouldn’t have access to.
All these devices follow the same principle of tracking the time between heartbeats and comparing that time to see how much it varies throughout the sample period.
One of the main metrics used when judging HRV is the Standard Deviation of the Interbeat Intervals of Normal Sinus Beats (SDNN). When taken over 24 hours, an SDNN below 70 ms is considered a warning sign of poor health, while 50-100 ms could indicate compromised health. An SDNN of over 100 ms is considered healthy. If the sample period is less than 24 hours, these figures may vary. For example, some consumer-focused apps that use a 60-second sample period consider the normal range for SDNN to be 30-96 ms.
Factors Influencing HRV
Your heart rate variability is regulated by the autonomic nervous system (ANS). There are two elements to the ANS: the sympathetic branch and the parasympathetic branch. When you’re at rest, your HRV is controlled by the parasympathetic branch, which is the “rest and recovery” side of the ANS. During times of stress, the sympathetic branch takes over and stress hormones cause a fight-or-flight response. It’s this difference in control that causes your HRV to be greater while you’re relaxed and lower when you’re exercising or stressed.
Other things that can impact your HRV include:
- Sex. Men typically have a higher HRV than women.
- Age. A person’s HRV will decrease as they get older.
- Hormone levels. Women may notice their HRV changes throughout their menstrual cycle.
- Body temperature. An elevated body temperature during an illness could alter your HRV.
- Underlying health conditions. Some metabolic disorders can lead to a lower HRV.
Relationship Between HRV and Health
It’s normal for your heart rate to vary depending on your activity level. A high HRV, meaning a relatively large difference in the time between consecutive heartbeats, is to be expected while you’re relaxed. During exercise or times of stress, your HRV may become lower.
While tracking heart rate variability trends can be interesting for a layperson, trying to interpret the data on a deeper level isn’t a good idea, especially given the relatively low accuracy of most consumer heart rate monitors. If your HRV is unusual, don’t panic, but talk to a doctor to set your mind at ease.
Applications of HRV in Wellness and Health Care
Tracking your HRV can help you spot the early warning signs of physical and mental fatigue earlier. You can use this to make decisions about how hard you’ll exercise if you have a workout planned that day or even how much you’ll try to get done at work.
Medical professionals may use HRV monitoring as part of a wider set of diagnostic tools to get an understanding of a person’s cardiovascular health.
Techniques to Improve HRV
If your HRV is far lower than normal, that might be a sign it’s time to relax both physically and mentally. Diaphragmatic breathing techniques, yoga and meditation can help. Other ways to improve your HRV include regular exercise, cutting down on smoking and alcohol, trying to maintain a healthy weight and learning stress management techniques.
If you’re struggling with stress or burnout, Sun Health Center may be able to help you. Our neurotherapy treatments can help people improve their mental health and rid themselves of mental blocks that might otherwise be holding them back from achieving their goals. Contact Sun Health Center today to request a consultation.
