Why Does Postdoctoral Researcher Rob ter Horst, PhD. at the Research Center for Molecular Medicine (CeMM) Vienna Make Accuracy Tests of the OURA Ring 3, But Does Not Use 3 Lead ECG Gold Standard Devices for his HR Tests?

Rob ter Horst tests the heart rate accuracy of the OURA Ring 3: Rob says he tests everything. But why does he not use 3 lead ECG gold standard devices for HR measurements, as the group of the cardiologist Milind Y. Desai at hte Cleveland Clinic in Ohio does? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6732081/ and makes tests at the …