Heart rate variability (HRV) and body position: lying down or sitting?
What is a Good Resting Heart Rate by Age & Gender? | WHOOP
How Physically Fit Are You? - Discovery Express
A cross-sectional study on upright heart rate and BP changing characteristics: basic data for establishing diagnosis of postural orthostatic tachycardia syndrome and orthostatic hypertension | BMJ Open
The postural orthostatic stress syndrome in childhood: HRV analysis and the active standing test