Heart rate variablity values are highest during teenage years and decline with age. People with a healthy lifestyle and/or
experience in meditation typically produce better/higher values. Training with HeartBreath can help raise your values.

High levels for RMSSD, pNN50, LF and Variability values are good, indicating raised parasympathetic activity. The higher the heart rate variability, the healthier, more vital, and biologically younger you are.

The computation of the parameters below is based on heartbeat data of a selected reference area with a duration of about one minute. This reference area is automatically set during and at the end of recording a session (the area with the best data) and can be adjusted manually on review of the session data.

Heart rate

The mean heart rate per minute in the reference range.

As a rule of thumb lower heart rates are better for relaxation capabilities and often related to  high heart rate variability.

Our heart beats approximately 100.000 times a day - that is 70 times per minute. With physical activation and stress, it beats faster, while relaxation and recovery calm the heartbeat.


The RMSSD value shows how much the heart rate changes from one heartbeat to the next. This value is an indicator of parasympathetic activity - but error prone to artifacts and cardiac arrhythmias.

RMSSD calculation: Square root of the mean of the sum of the squared differences between successive RR intervals.


A high SDNN value stands for high heart rate variability.

It can be compared for the same duration of measurement and constant activity only, as various factors of activities have an influence on the value. The SDNN value depends on your age.

SDNN calculation: Standard deviation of the RR intervals.


The pNN50 value is a measure of the activity of the Vagus recovery nerve and of the general reserves we have. Compared to SDNN, which is also an indicator of our parasympathetic system, the PNN50 is more stable and less sensitive to various influences.


pNN50 calculation: Percentage of consecutive RR intervals that differ by 50 ms or more.

E-I Difference

Our heart beats faster when inhaling than exhaling. The E-I difference value is the difference between the largest and smallest RR intervals of a respiratory cycle. The larger the difference, the more adaptable your organism is and the higher your heart rate variability. Due to the calculation basis using median values, these values are relatively robust against artifacts.


The function of the body which best represents the responsiveness of the heart is called respiratory sinus arrhythmia (RSA). Behind this complicated term hides the synchronous relationship of breathing and heartbeats. If you have ever attached yourself to a hospital ECG with sound, you may have noticed that the "beep" sound was faster when inhaling and slower when exhaling. That's the point.

The adaptation of the heart to respiration has been shown to be a very interesting HRV parameter, rising with positive emotions and falling with negative ones. HeartBreath provides you with a simultaneous feedback of breathing and heart rate which therefore helps on learning to reconcile these physiological parameters.

Variability calculation: Square root of the power in the frequency band

(RSA-Frequency - 0.015 Hz) to (RSA-Frequency + 0.015 Hz).

RSA-Frequency = breaths per minute / 60


This power area is attributed to sympathetic as well as parasympathetic activity. Parasympathetic influences are primarily activities that take place at low respiratory rate (<7 breaths / minute), such as Breathing exercises or yoga. Furthermore, this frequency range is related to the blood pressure rhythm. The so-called Baroreflex loop, which maintains blood pressure, has an intrinsic frequency of about 0.1 Hz.

The power in the "Low-Frequency" band from 0,04 Hz to0,15 Hz.


Frequencies in the HF band are attributed to the parasympathetic nervous system, our recovery nerve.


The power in the "High-Frequency" band from 0,15 Hz to 0,4 Hz.

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