I can't test your app, since I don't have an iPhone, but I'm hoping you could answer a vaguely related question for me. One of my COVID readings was Breath: The New Science of a Lost Art , by James Nestor. Its author says, "humans have lost the ability to breathe correctly". Like your app, it proposes a lot of breathing exercises. It explains their benefits in terms of increasing CO2 tolerance, and believes that we'v…
For practicing breath holding, "co2 tables" is the exercise to go for, btw. I find it very relaxing in a sort of meditative "ignore the burning pain" sense, but not sure I'd recommend it vs the app in the OP hehe.