Measuring HRV can be a super helpful thing to get into for anyone athletic out there looking to improve/evaluate themselves and their training. This app takes all the guesswork and complication out of it...with all the complex stats and features still available for nerds like me. Camera measurements are pretty accurate (keep them short though...holding the phone can actually raise your heart rate a teeny bit). The only gripe I have is that sometimes youll get random +40 bpm spikes, and it will ruin your test. I plan on getting the Polar monitor (only about $40 on amazon) soon so my tests will be much more accurate.
All in all if you want to measure HRV...shell out the couple bucks for this app, and dont bother with anything else. Its all you need...and all youll want once you start analyzing your own data.
jbone666 about HRV4Training