A Novel Digital Phenotype of Physical Activity: Associations with Heart Rate Fragmentation
medRxiv [Preprint]. 2026 Oct 11:2026.10.08.26365083. doi: 10.64898/2026.10.08.26365083.ABSTRACTBACKGROUND: Heart rate fragmentation (HRF) has emerged as a novel marker of sinoatrial instability and neuroautonomic dysregulation and is a predictor of incident cardiovascular disease (CVD) events and ca

