SimpleRmmssdAlgorithm

The Simple RMSSD algorithm is a basic auto-configuring version of the Decreased RMSSD algorithm. It lacks the customisation that is available in the Decreased RMSSD algorithm and uses periods of inactivity to estimate the RMSSD. The following figure shows an overview of the Simple RMSSD algorithm. The boxes in yellow show the configurable parameters. Further information on Heart Rate Variability and RMSSD is in the description of the Decreased RMSSD algorithm.

Sensor requirements

To use the Adaptive Rmssd Algorithm, the ECG and Activity sensor EcgMove 3 or EcgMove 4 is required.

Algorithm description

The inputs for the algorithm are:

• HRV RMSSD [ms], sample rate 1/min

• Movement Acceleration [g], sample rate 1/min

Activity Levels (inactive, sedentary, and active) are derived from Movement Acceleration. The following cut points are used (the selection of these cut points is based on measurements performed at movisens and KIT):

• Inactive / Sedentary: 20 mg

• Sedentary / Active: 200 mg

To be sure that the participant is in the desired activity level and HRV parameters have settled, cool down blocks are used and can be configured manually (Minimum duration in sedentary or inactivity [min], Minimum duration in sedentary [min]). RMSSD mean values are calculated when the participant is in the sedentary category. This assures that the RMSSD mean value is not too high or too low. This would be the case if RMSSD values in inactive or active levels were used. The RMSSD values acquired in inactive or sedentary level are then compared to a threshold, defined as a ratio between 0 and 1 (in the RMSSD ratio to trigger movisensX [0..1]), from the mean RMSSD value. If the RMSSD values are below the set threshold for a defined time period (minimum duration in low RMSSD) a trigger is sent to movisensXS.

Parameter description

The following parameters can be customized for the simple rmssd algorithm:

• Minimum duration in sedentary or inactivity [min]: Default 10 minutes
• Minimum duration in sedentary activity [min]: Default 10 minutes
• Minimum duration in low rmssd [min]: Default 5 minutes
• RMSSD ratio to trigger movisensXS [0...1]: Default 0.7