Nice man! That app sounds like a great idea when I can't do bag breathing. I'm gonna download it.
Thanks :) Yeah it is a great app imo.
It may be helpful to measure a number of additional parameters, other than just HR. such as: (1) weight; (2) blood pressure; (4) cardio performance capacity; and (5) LBM level ... Just a suggestion.
I agree, I was thinking about this as well. I could try morning body temps, but seems to take quite some time to get a good reading. What is LBM btw? I also @haidut talking about some thing that can measure the CO2 level in your lungs, maybe that would be a nice measurement.