Heart rate variability (HRV) is widely used to assess what's going on with a person’s body — there are about 20,000 relevant studies on PubMed. Note that HRV measurement is not an electrocardiogram (ECG) recording, and it can't be used as a substitute for ECG or a medical check-up.

In addition to all standard HRV metrics, which you can see in the chart message, we offer you our own science-backed yet easy-to-understand scores — Productivity, Energy, and Stress, which we illustrate with liquid.

Doctors and scientists have been widely using heart rate variability to monitor athletes’ and astronauts’ physical fitness and performance. And we interpret HRV data using our algorithm trained with 16 mln measurements of 2 mln users. Most of them also track their mood, how they feel, how tired and stressed they are. And take research-based self-tests to evaluate their stress, fatigue, anxiety, and concentration levels.

When you take a measurement, we use this enormous database to compare your HRV metrics with what they meant in terms of Productivity, Energy, and Stress for other people of the same age and gender and with a similar lifestyle as yours. That's how we calculate your Productivity, Energy, and Stress scores.

Our calculations of your Productivity, Energy, and Stress scores are based on our studies. They are not intended to substitute professional medical advice, diagnosis, or treatment and do not guarantee an accurate evaluation of your physical and mental health. These scores should be seen as an advanced data-driven analysis that is here to make sense of your HRV metrics and make them easier to understand.

Productivity

Productivity indicates your current capacity to deal with intellectual tasks of varying complexity — to think and analyze.

  • An increase in your productivity score means that you can take on more ambitious tasks and stay focused for longer periods of time.
  • If you have average productivity scores and energy levels, it’s better to take on some routine work.
  • When your productivity score is low, it’s best to not burden your brain with complex or unfamiliar tasks — you’ll just end up procrastinating.

Good productivity requires optimal stress and energy levels. High productivity scores are great, but it’s okay to feel distracted or too tired to think properly from time to time.

Energy

Energy reflects your body’s ability to support processes like metabolism, movement, and digestion, as well as to recover properly. Energy level determines how well you can maintain a stable internal environment, or homeostasis, and perform physical activity. While high energy scores are definitely something to be happy about, keep in mind that it’s natural to be low on power in the evening.

  • Check if you have enough energy to do everything you have planned. If you’re low on energy, your plans to conquer the world may have to wait. If you see high scores, on the other hand, don’t miss the opportunity to take on a challenge.
  • Know in advance if you risk feeling spent soon. Look at your Energy trend to see if your body is using energy, actively recovering, or spending and saving energy at an equal pace.

At times, you may be full of energy, even if you don’t feel that way. Energy is directly related to your parasympathetic nervous system activity. Sometimes, when the parasympathetic system is at work, with your body actively recovering and storing energy, your score may seem high compared to how you feel. In this case, you’re likely going to feel a surge of energy a little later — just give the rest of your body a bit of time to catch up.

If you’re sick but still have high energy scores, your body is doing a decent job maintaining homeostasis.

Stress

Stress reflects the level of physical stress and its effect on the body.

Extremely low or extremely high stress is usually not a good sign — it means you’re under way too much pressure or way too tired. It’s natural to have such stress levels after something challenging, like a workout. However, it’s important to make sure your stress levels bounce back to normal soon after.

I’m in the best of moods and don’t feel stressed at all, but my stress score is high. Is that possible?

Yes. We measure physical rather than emotional stress. They may impact one another, but they’re not the same. For example, your body’s systems may be strained after a workout, while your mood is good. Likewise, a roller coaster ride will likely leave you feeling great, but it will also increase your stress level due to the adrenaline boost. That is why it’s so important to keep tabs on physical stress: what you feel may not coincide with what your body is actually experiencing. When you’re not in touch with your body, you risk overdoing it and may end up with chronic stress or other health problems, such as frequent colds.

Are high stress scores always bad?

No. For example, increased stress after a workout is okay. But if it is still high the next day, after you have had a good night’s sleep, with no other stress factors affecting you, you might have gone a little too far. Why not cut yourself some slack the next time?

My stress score is low, but it is colored red or blue, not green. Why is that?

It means your body is overwhelmed and is having trouble kicking it into gear. It has not recovered properly or is too tired. One might think it’s good to have low stress scores, but the thing is you do need some stress in order to pull it together and get things done. Both too low and too high stress levels are not good for you.

Resilience

Resilience is your body’s ability to maintain homeostasis regardless of what may be happening to you. High resilience lowers your risk of getting sick or developing complications after an illness.

Our algorithms calculate it based on heart rate variability analysis. Resilience has nothing to do with the intensity of any symptoms you may be experiencing. For example, you may feel better with a body temperature of 37–38 °C (99.5–101 °F) than of above 39 °C (102.5 °F), but your resilience may be worse.

Important note: This content is here for informational purposes only and may not be used for medical assessment or diagnostic purposes. If you feel unwell, please consult a medical professional.

Balance

Balance reflects how active your nervous system is as a whole, and shows the relative activity of its two parts — the SNS and PSNS — in percent.

The SNS (sympathetic nervous system) is responsible for the body’s “fight-or-flight” response, while the PSNS (parasympathetic nervous system) is responsible for “rest-and-digest” functions. Their relative activity may change throughout the day depending on a number of different factors, and many people who practice yoga or meditation like to track how their practice tips the balance.

However, it is the sum of their activity that’s most important — a number that’s too low may indicate that you’re exhausted and need some rest.

Coherence

Coherence shows how synchronized your brain, heart, and respiratory system are.

When your systems are synced up, you are less irritable, tend to think more rationally and work more effectively, are ready to make important decisions and complete complex tasks, and feel balanced in general.

Better coherence may be achieved with breathing practices, such as coherent or deep breathing, as well as positive emotions and thoughts. See more in these videos: part 1 and part 2.

HRV Score

HRV Score assesses heart rate variability based on lnRMSSD — the natural logarithm of RMSSD. RMSSD, in turn, is a key variability metric reflecting parasympathetic nervous system activity.

The higher your HRV Score is, the better off you are. 100% means ideal variability, when the sky is your limit — whether we’re talking mental or physical activities.

Important note: Free users can see all scores and their detailed descriptions during the first 5 days following signup. After that, only Productivity, Energy, and Stress scores remain available. To get unrestricted access, upgrade to Welltory Pro. See what other benefits you’ll get with Welltory Pro.

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