An interesting app from Marco Altini.

HRV measurement by using the camera on your iPhone (not Android). Some models (iPhone 5 or 6) can take HRV-accurate readings from your finger suing the phone’s camera effectively as a heart rate monitor.

Here are some more links if you want to find out more. Click on the icon and it will take you to the store on iTunes.

http://www.hrv4training.com/blog/orthostatic-hrv-measurements-training-and-recovery

http://www.hrv4training.com/

http://www.hrv4training.com/blog/heart-rate-variability-using-the-phones-camera