As far as this test for knowing the condition of one's heart, I was thinking about the difference if one person is a nervous shallow breather and another one is relaxed and takes deeper breaths naturally and how that effects the test. High stress people usually have more heart problems.
I use to be a shallow breather so I have noticed the difference for myself. The ML protocols have made me more relaxed and so a normal breath is deeper now than back then, and because the breath is deeper (more oxygen, thanks to alkaline minerals), I can hold it longer.