Wrist-worn smart watches and fitness monitors have become widely adopted by consumers and are gaining increased attention from researchers. While accuracy of chest strap, electrode-based HR monitors have been confirmed, research shows that fitness trackers may not be the best way to measure heart rate.
While some wrist-worn monitors are more accurate than others, studies show they aren’t as accurate as chest-worn heart monitors. Marc Gillinov, MD, chairman of the Department of Thoracic and Cardiovascular Surgery at the Cleveland Clinic, has studied the accuracy of the devices.
Dr. Gillinov and colleges recruited 50 healthy adults and randomly assigned each of them to wear two of four wrist-worn fitness devices with heart monitors, one on each wrist. The participants wore the devices while walking or running on a treadmill. All the participants also wore standard EKG electrodes and a chest-worn monitor.
Heart rate was measured with participants resting, walking, or running on a treadmill at various settings. The participants exercised for three minutes at each setting, and recorded their heart rate at the three-minute point. Recovery rate was also measured at 30, 60, and 90 seconds at the end of the three minutes.
According to the researchers, the most accurate readings were from the chest-worn monitor. Other studies have also found that fitness devices underestimate heart rate and accuracy diminishes during exercise.
Dr. Gillinov says wrist-worn monitors are fine for recreational use, but probably won’t be replacing EKGs in the medical setting any time soon.
Wang R, Blackburn G, Gillinov, M, et al. Accuracy of Wrist-Worn Heart Rate Monitors. JAMA Cardiol. 2017;2(1):104–106. doi:10.1001/jamacardio.2016.3340