BeatMonitor is an iPhone app that uses the iPhones microphone to calculate your bpm (beats per minute ) . Simply place the iPhone on a vein i.e. over your heart or over your wrist and then press start.

In addition BeatMonitor can also be used to calculate your MHR (Maximum hear rate).
*You should know your maximum heart rate to establish boundaries during training. Most recommendations suggest targeting a heart rate between 55% and 85% of your maximum heart rate for a period of time, say 30 minutes, to build your aerobic base.

BeatMonitor can be used with the iPhone and iPod touch(requires microphone headset).


=========================================
To use you must first be able to detect a vein, this will not work if you cant detect a vein.
First place the iPhone microphone firmly on a vein and press start. You can tell if BeatMonitor can find a vein by the digital sine wave display. If you don’t see a consistent sine wave when you press start then you still need to find a vein. Best location is just over your heart, or on your wrist. BeatMonitor will not work through clothes must be against your body.
Once you can consistently find a vein BeatMonitor can then calculate your bpm.

*BeatMonitor works best with the onboard microphone.