Everything you need to know about photoplethysmography (PPG), the technology behind heart rate measurements in fitness watches and smart rings. When you purchase through links on our site, we may earn ...

Heart rate variability offers a closer look at how your heart behaves from one beat to the next. While heart rate measures the average number of beats per minute, heart rate variability bases a ...

Anne R. Crecelius does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond ...