HRV is normally calculated at rest. Studies have shown that HRV is difficult to interpret during periods of activity (please refer to the document Hexoskin-MeasureHRV-Document-EN-Print). Also, each time you move or talk, your HRV changes. Therefore, it is possible that the HRV was not calculated by our algorithms because the activity detected was beyond the threshold to be respected for such calculations (i.e. you moved too much during the recording).
Another possibility is that your ECG signal was too unreliable for the Hexoskin algorithms to calculate any HRV value.
We suggest that you perform a rest activity (under Fitness Tests in the Hexoskin App). Make sure this time that you wet or applied conductive cream on the cardiac sensors and that you limit movement for the duration of the recording.
Keywords: RMSSD, heart rate variability, data quality assessment, data analysis, EKG, biofeedback, noise, noisy