I have a problem with the heart rate reading I see 130 or above but the app on my phone only shows 123 as max why. Also when I get to 118 or above I accelerate and am working harder the heart rate goes down some times to the 80 s so no more accurate than my Aldi watch which was under $50 . Ps I am 70 so I would like to have reliable heart rate reading while exercising but this is very in accurate