No other external hardware is required, all you need is your smartphone. Camera is not used! Measuring is based on motion sensors. Your recovery heart rate, the speed at which your heart rate returns to normal after exercise, can indicate physical cardiac condition and the risk of certain diseases.
The app is totally secure for downloading. Emil Doležal has designed Recovery Heart Rate Pro that lies within the Health & Fitness category. On Google Play, the tool is rated 3.6 by its users.
This application has been downloaded and set up by over 10 users and its most recent update was released on May 5, 2017. It's free of charge to download the installation package of Recovery Heart Rate Pro, also, you can read users' reviews on Droid Informer. The app runs on Android 4.0.3 and above.