How do fitness trackers measure your heart rate?

Description

"PPG sensors measure changes in blood volume and pulse pressure, and then convert these metrics into heart rate measurements," explains Dr. Peter Søgaard, professor of cardiology at Aalborg University and chief medical officer at VentriJect. He further explains that the accuracy of photoplethysmography (PPG), a technique used by fitness trackers to measure heart rate, can be affected by factors such as tracker placement, body temperature, skin thickness, and cardiovascular disorders. He also notes that skin contact and temperature can impact PPG measurements. (Summary provided by Infomedia). Sources:USA Times, 14-03-2025Live Science, 14-03-2025Network Today, 14-03-2025American Talk, 14-03-2025