To eliminate the need for a chest strap MIO use optical sensing (if you are techy - photoplesmographic technology). In optical sensing, a light is shone onto the skin, allowing the measurement of blood flow through the capillaries and the determination of heart rate.
The technology has existed for some years - the heart rate monitor finger clip you may see at the hospital uses it. Until now, the technology could not be used on athletes, or anyone moving around, because the clutter of other signals generated by noise from movement would interfere with the readings being captured by the optical sensor. MIO Alpha solves this with a built-in accelerometer to compensate for signal disturbances generated by motion, while noise-filtration software ensures a clear signal is delivered to the Alpha’s micro-processor. Optimizing all of these aspects required significant software development, testing and multiple design iterations. The result is a device that achieved a 0.99 correlation with EKG in independent testing at San Francisco State University. MIO Alpha provides continuous, EKG-accurate heart rate readings at running speeds higher than 14 mph.
New for 2016, PAI - Your heart rate is the single-most accurate reflection of your body’s response to physical activity, which is directly linked to your health. The new Mio PAI app works exclusively with Mio wearables and translates your heart rate data and personal profile information into one simple, meaningful metric: Your PAI score. Your total PAI score reflects heart rate data from the past 7 days, and if you keep a minimum PAI score of 100, you are helping your body maintain a top-notch health profile — maximizing your lifespan and preventing lifestyle-related diseases.