Non-Linear HRV Analysis

Non-Linear methods have become popular for visualizing HRV. In our Personal Pro and Team Dashboards, we provide a visual tool called a Poincare Plot. These are found in the reading details as well as the printable PDF reports.

The most common way to analyze the Poincare plot is to apply an ellipse to the scatter plot.

There are 2 main features of the Pointcare plot: Standard deviation 1 (Sd1), which mainly correlates to short-term variability influced by the respiratory sinus arrhythmia. It can also correlate to HF power.

The second is Standard deviation 2 (Sd2), which measures the short-term and long-term variability.

The total area of the ellipse represents the total HRV, and correlates with baroreceptor reflex, LF, HF, and RMSSD.

For longer readings, the SD1/SD2 ratio can be correlated to the LF/HF power ratio.

In general, a larger ellipse correlates to more variability and therefore a healthier, younger demographic.

For a deeper dive into Poincare plots and other methods of analyzing HRV, check out our Foundations of Heart Rate Variability Course.