The Us Army Research Institute of Environmental Medicine and the Oak Ridge Institute for Science and Education tested the Adinstruments Equivital EQ02 and compared the Accuracy to a Polar H10 chest strap. https://apps.dtic.mil/sti/pdfs/AD1154187.pdf The authors concluded, that the Equivital: is an acceptable body sensor for continuous heart rate monitoring of work/rest cycles across the physiological …