Reminder: RMSSD and SD1 are identical heart rate variability metrics

Area of Science:

• Cardiology
• Physiology
• Biomedical Engineering

Background:

• Heart rate variability (HRV) assessment is crucial for understanding cardiac autonomic nervous system modulation.
• Short-term HRV is frequently quantified using the root mean square of successive differences (RMSSD) and SD1, a component of Poincaré plots.

Purpose of the Study:

• To clarify that RMSSD and SD1 are mathematically and empirically identical metrics for HRV analysis.
• To alert researchers and clinicians to the redundancy of using both RMSSD and SD1 in HRV studies.

Main Methods:

• Empirical validation demonstrating the equivalence of RMSSD and SD1.
• Mathematical proof confirming the identity of RMSSD and SD1 metrics.

Main Results:

• RMSSD and SD1 yield identical quantitative values when applied to HRV data.
• The homology between RMSSD and SD1 is not widely recognized in current literature.

Conclusions:

• The use of both RMSSD and SD1 in HRV studies represents redundant data.
• Avoiding the simultaneous use of RMSSD and SD1 is recommended to ensure accurate interpretation of cardiac autonomic function and prevent potential misinterpretations in research.