Heart Rate Variability (HRV) has shifted from a clinical prognostic tool to a mainstream metric for athletes and fitness enthusiasts. As people increasingly rely on wearable devices and smartphone applications to track their "heart health," the question of becomes paramount. 2. Defining the Metrics
Validity of Smartphone Heart Rate Variability Pre - PMC - NIH Heart – Mr Validity
The most common time-domain metric is the Root Mean Square of Successive Differences (RMSSD) , which specifically tracks parasympathetic (recovery) activity. Heart Rate Variability (HRV) has shifted from a
Scientific validity requires comparing new technology against the established "gold standard": the . Heart – Mr Validity