When it comes to our health, it's pretty easy today to measure and track all sorts of information. We can measure our weight, blood pressure, number of steps, calories burned, heart rate, and blood sugar from the comfort of our own home. Researchers have now explored another data point, heart rate variability (HRV), as a possible marker of resilience and behavioral flexibility.

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What is HRV?

As heart rate variability (HFV for short) or heart rate variability (English: Heart rate variability, HRV) is the measure of the variation over time between individual heartbeats. These fluctuations are controlled by the autonomic nervous system (ANS), which regulates our heart rate, blood pressure, respiration, digestion, and other important tasks. The ANS is divided into two major components: the sympathetic system, which adjusts the organism to increase activity (“fight or flight”), and the parasympathetic system, which controls the functions of the rest and regeneration phases (“rest and digest”).

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The brain is constantly processing information in a region called the hypothalamus. The ANS delivers signals to the hypothalamus, which then tells the rest of the body to either stimulate or relax various functions. The ANS not only reacts to a bad night's sleep or an unpleasant encounter with the boss, but also to good news or to the delicious, healthy food that was on the plate for lunch. Our bodies process all kinds of stimuli and life goes on. However, when we have persistent triggers such as stress, lack of sleep, unhealthy diet, disturbed relationships, isolation or loneliness, and lack of exercise, this balance can be disrupted and our “fight or flight” or fight-or-flight response can go into overdrive.

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Checking heart rate variability

The gold standard is the analysis of an electrocardiogram made in a doctor's office. But in recent years, companies have launched apps and wearable heart rate monitors that do something similar. The accuracy of these methods is still being tested, but the technology used in the devices is getting better and better. If you want to try it out, you should use chest strap devices, as they usually provide more accurate HRV measurements than wrist devices.

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HRV can be a non-invasive way to identify imbalances in the autonomic nervous system. Age, gender, respiration and fitness level play a role, but in principle, the higher the difference between the intervals between the heartbeats, the better. This means that the system is then in a relaxed state. However, if the variation between consecutive heartbeats tends to be lower, the system is more in a fight-or-flight mode.

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This suggests a few interesting options. People with high HRV may have better cardiovascular fitness and be more resistant to stress. However, this cannot be said too generally, because HRV decreases sharply with increasing age. 20 to 25 year olds normally have an average HRV in the range of 55 to 105, while 60 to 65 year olds usually have values between 25 and 45.

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Nevertheless, HRV can provide personal feedback on lifestyle and motivate people to consider steps towards a healthier life. Integrating more mindfulness, meditation, good sleep and, above all, physical activity into daily life will be reflected in the change in HRV. For those who love data and numbers, this could be an interesting way to track the nervous system's responses not only to the environment, but also to emotions, thoughts, and feelings.

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Conclusion

There are questions about the accuracy, reliability, and general utility of HRV measurement. While HRV has been linked to overall physical fitness, the correlation between changes in HRV and how the autonomic nervous system works still needs further research. However, anyone who wants to use HRV as another way to determine their health data should not be too reassured about a high HRV or too concerned about a low HRV. Rather, HRV can be seen as a possible parameter of how our body and mind react to our daily experiences.