心率变异性（HRV）是通过分析心电图（ECG）的Beat-Beat间隔的时间序列来确定的。

HRVanalysis has become one of the most popular methods of ANS evaluation. It is based on the observation that even at rest the duration of RR intervals is not constant but continually fluctuates around the mean value. ECG, blood pressure, or arterial pulse recordings can be used to investigate the interplay between sympathetic and parasympathetic nervous systems.

PowerLab和LabChart形成了一个灵活的，可自定义的系统，用于记录和分析心率可变性（HRV），以针对人类自主系统研究的广泛信号。