The technology works by turning your iPhone or iPad into a biosensor that measures how much light your face reflects. Every time your heart beats, blood is pumped into your face, changing how much light is reflected. The app measures those tiny changes in reflected light and calculates a resting heart rate accurate to within 3 beats per minute (bpm).
Using Cardiio is somewhat easier than trying to find a pulse on your wrist or neck and it works best when your face is well lit and you are at rest.The developers’ sense of humour shines through in random phrases like “sautéing kraken tentacles” that alternate on screen with some informative heart health facts to keep you entertained during the 10-12 seconds you need to hold still for a pulse reading.
The app keeps track of your stats on your personal dashboard, displaying how you are trending over time by day, week or 30-day average. Your fitness level is shown on a scale of “fair” to “fit” and you can see how your resting heart rate compares to the average US person, who has a resting heart rate of 72 bpm, and Lance Strongarm (sic) who boasts a score of 32 bpm. Cardiio costs $4.99 and is listed in the iTunes App Store as the #1 top paid health and fitness app in 14 countries.
Measuring resting heart rate is a good measure of overall fitness. In general, the more fit you are, the lower your heart rate because less effort is required to pump your 5 L of blood throughout your body. The Cardiio app uses your heart rate information to calculate your potential life expectancy and compares that to a different animal each time you click on the Insight feature. The accuracy of any prediction improves with a greater number of data points, but based on some readings this morning, it looks like I may be on the right track for a long life.